Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE: CURATIVE
CROSS REFERENCE TO RELATED APPLICATIONS
The present application also claims priority from provisional Pat. App. Nos.
63/145,939 filed
on Feb. 4,2021; 63/274,443 filed on Nov. 1,2021; and 63/297,569 filed on Jan.
7,2022, all
of which previous applications are incorporated by reference herein in their
entireties.
FIELD OF THE INVENTION
The present disclosure related to methods for producing natural products that
may be made
utilizing the curative disclosed herein. The natural products have physical
properties similar
to synthetic coated fabrics, leather-based products, and foam products.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
No federal funds were used to develop or create the invention disclosed and
described in the
patent application.
BACKGROUND
Various manufacturing methods are utilized for footwear construction depending
on the
complexity of the final design. The simplest designs may utilize only one or
two discrete
types of materials as seen in flip-flops, slides, sandals, and CrocsTM. In
these types of
footwear one material can serve for the entire footbed and either the same or
a different
material may be used for the top straps. At the other extreme, some
performance running
shoes or hiking boots may use 10-20 different types of materials for their
specialized
attributes.
It is desirable to be able to create footwear that is entirely recyclable
without requiring
deconstruction of the shoe. This may be relatively easy to achieve in simple
designs that may
be molded of one particular thermoplastic (whether foamed, solid, or both). In
more complex
footwear that contain an upper of one type of material and a midsole foam of
another type of
material and an outsole rubber of another type of material the recycling of
such a shoe
requires deconstruction. US11026477 discloses a shoe that is comprised of bio-
based and/or
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recycled materials and seeks to minimize the number of discrete material
types; but such shoe
still ultimately requires deconstruction at the end-of-life in order to be
fully recycled.
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BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of
this
specification, illustrate embodiments and together with the description, serve
to explain the
principles of the methods and systems.
FIG. 1 is a chemical reaction formula and schematic for at least one
illustrative embodiment
of the curative disclosed herein.
FIG. 2A is an illustration of an epoxidized natural rubber-based material
produced using a
relatively lower viscosity resin that was allowed to penetrate throughout the
flannel substrate
resulting in a suede or brushed-looking surface.
FIG. 2B is an illustration of an epoxidized natural rubber-based material
produced using a
relatively higher viscosity resin that was allowed to only penetrate partly
through the flannel
substrate resulting in a glossy polished-looking surface.
FIG. 3 is an image of an epoxidized natural rubber-based material produced in
accordance
with the present disclosure.
FIGS. 4A, 4B, and 4C are views of portion of an epoxidized natural rubber-
based material
produced in accordance with the present disclosure that may be used for
construction of
wallet wherein each version of the epoxidized natural rubber-based material is
made with a
different texture.
FIG. 5 is a view of a plurality of pieces of a epoxidized natural rubber-based
material
produced in accordance with the present disclosure that may be used for
construction of
wallet.
FIG. 6 is a view of the plurality of pieces of the epoxidized natural rubber-
based material
produced in accordance with the present disclosure assembled as a simple
credit card wallet
or carrier having the appearance, rigidity and strength as one of ordinary
skill would expect
with natural animal-hide leather.
FIG. 7 is a resin impregnated fabric that may be utilized in accordance with
the present
disclosure.
FIG. 8A is a top view of a ball made according to the present disclosure.
FIG. 8B is a side view of a ball made according to the present disclosure.
FIG. 9 provides a graphical representation for two stress-strain curves of two
different ENR-
based materials.
FIG. 10A provides a depiction of an ENR-based material configured with
inherent
functionality for engaging a belt buckle.
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FIG. 10B provides a depiction of the ENR-based material from FIG. 10A after
engagement
with a belt buckle.
FIG. 11 provides a depiction of an ENR-based material having grooves and
ridges formed
therein.
FIG. 12 provides a depiction of an illustrative embodiment of a molding system
that may be
used for certain ENR-based materials.
FIG. 13 shows a chemical representation of a cured thermoset material.
FIG. 14 shows a chemical representation of mechano-chemical reversibility.
FIG. 15 shows a series of images during the mechano-chemical processing of
thermoset
material.
FIG. 16 shows a series of rheometer data from material that is repeatedly
mechano-
chemically processed.
FIG. 17 shows a series of rheometer data for increasing cure temperatures.
FIG. 18 shows pancake-like discs of foam product produced according to one
embodiment of
the present disclosure.
FIG. 19 shows a gradient of porosity associated with variation in curing
temperature.
FIG. 20 shows a foam slab made according to various aspects of the present
disclosure.
FIG. 20A is a detailed view of a portion of the foam slab shown in FIG. 20.
FIG. 21 shows an illustrative method of making the foam slab shown in FIGS. 20
& 20A.
FIG. 22 shows material(s) manufactured with compounds according to the present
disclosure
that has been ground for recycling.
FIGS. 23A-23D provide schematic representations of four steps for an
illustrative method of
making one type of article.
FIGS. 24A-24D provide schematic representations of four steps of another
illustrative
method of making one type of article.
FIGS. 25A-25F provide schematic representations of four steps of another
illustrative
method of making one type of article.
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DETAILED DESCRIPTION
Before the present methods and apparatuses are disclosed and described, it is
to be
understood that the methods and apparatuses are not limited to specific
methods, specific
components, or to particular implementations. It is also to be understood that
the terminology
used herein is for the purpose of describing particular embodiments/aspects
only and is not
intended to be limiting.
As used in the specification and the appended claims, the singular forms "a,"
"an," and "the"
include plural referents unless the context clearly dictates otherwise. Ranges
may be
expressed herein as from "about" one particular value, and/or to "about"
another particular
value. When such a range is expressed, another embodiment includes from the
one particular
value and/or to the other particular value. Similarly, when values are
expressed as
approximations, by use of the antecedent "about," it will be understood that
the particular
value forms another embodiment. It will be further understood that the
endpoints of each of
the ranges are significant both in relation to the other endpoint, and
independently of the
other endpoint.
"Optional" or "optionally" means that the subsequently described event or
circumstance may
or may not occur, and that the description includes instances where said event
or
circumstance occurs and instances where it does not.
"Aspect" when referring to a method, apparatus, and/or component thereof does
not mean
that limitation, functionality, component etc. referred to as an aspect is
required, but rather
that it is one part of a particular illustrative disclosure and not limiting
to the scope of the
method, apparatus, and/or component thereof unless so indicated in the
following claims.
Throughout the description and claims of this specification, the word
"comprise" and
variations of the word, such as "comprising" and "comprises," means "including
but not
limited to," and is not intended to exclude, for example, other components,
integers or steps.
.. "Exemplary" means "an example of' and is not intended to convey an
indication of a
preferred or ideal embodiment. "Such as" is not used in a restrictive sense,
but for
explanatory purposes.
Disclosed are components that can be used to perform the disclosed methods and
apparatuses.
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These and other components are disclosed herein, and it is understood that
when
combinations, subsets, interactions, groups, etc. of these components are
disclosed that while
specific reference of each various individual and collective combinations and
permutation of
these may not be explicitly disclosed, each is specifically contemplated and
described herein,
for all methods and apparatuses. This applies to all aspects of this
application including, but
not limited to, steps in disclosed methods. Thus, if there are a variety of
additional steps that
can be performed it is understood that each of these additional steps can be
performed with
any specific embodiment or combination of embodiments of the disclosed
methods.
The present methods and apparatuses may be understood more readily by
reference to the
following detailed description of preferred aspects and the examples included
therein and to
the Figures and their previous and following description. Corresponding terms
may be used
interchangeably when referring to generalities of configuration and/or
corresponding
components, aspects, features, functionality, methods and/or materials of
construction, etc.
those terms.
It is to be understood that the disclosure is not limited in its application
to the details of
construction and the arrangements of components set forth in the following
description or
illustrated in the drawings. The present disclosure is capable of other
embodiments and of
being practiced or of being carried out in various ways. Also, it is to be
understood that
phraseology and terminology used herein with reference to device or element
orientation
(such as, for example, terms like "front", "back", "up", "down", "top",
"bottom", and the
like) are only used to simplify description, and do not alone indicate or
imply that the device
or element referred to must have a particular orientation. In addition, terms
such as "first",
"second", and "third" are used herein and in the appended claims for purposes
of description
and are not intended to indicate or imply relative importance or significance.
Element Description Element Number
Natural leather-like material (suede finish) 100
Natural leather-like material (glossy finish) 100'
Fabric 102
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Fabric extension 103
Polymer 104
Expanding foam 200
Floating platen 210
Lifting platen 220
Mold 400
Sole preform 401a
Sole 401b
Foam injection aperture 401c
Strap 402
Adhesive material 403
Foam footbed preform 404a
Foaming/foamed footbed 404b
Metal plate 405
Foaming compound mold 406
Injection port 406a
Injection barrel 407
Last 408
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Preformed upper 409
1. Curative (pre-polymer)
Disclosed is a curative comprised of an epoxidized triglyceride (which may be
a plant-based
oil such as vegetable and/or nut oil(s) and/or a microbial oil such as that
produced by algae or
yeast), naturally occurring polyfunctional carboxylic acids, and at least some
grafted
hydroxyl-containing solvent. Examples of such epoxidized triglycerides
comprised of plant-
based oils include epoxidized soybean oil (ESO), epoxidized linseed oil (ELO),
epoxidized
corn oil, epoxidized cottonseed oil, epoxidized canola oil, epoxidized
rapeseed oil,
epoxidized grape seed oil, epoxidized poppy seed oil, epoxidized tongue oil,
epoxidized
sunflower oil, epoxidized safflower oil, epoxidized wheat germ oil, epoxidized
walnut oil,
and other epoxidized vegetable oils (EV0s). Generally, any polyunsaturated
triglyceride with
an iodine number of 100 or greater may be epoxidized and used with the
curative as disclosed
herein without limitation unless otherwise indicated in the following claims.
Such epoxidized
triglycerides are generally known to be biodegradable. Examples of naturally
occurring
.. polyfunctional acids include citric acid, tartaric acid, succinic acid,
malic acid, maleic acid,
and fumaric acid. Although specific illustrative embodiments may denote one
type of oil
and/or acid, such embodiments are not meant to be limiting in any way unless
otherwise
indicated in the following claims.
.. The curative as disclosed herein is a reaction product between an
epoxidized vegetable oil(s)
and a naturally occurring polyfunctional carboxylic acid conducted in a
solvent that is
capable of solubilizing both the epoxidized vegetable oil(s) and a naturally
occurring
polyfunctional carboxylic acid, wherein the solvent contains at least some
portion of a
hydroxyl-containing solvent (i.e., an alcohol) that reacts with at least some
portion of the
carboxylic acid functional groups that are contained on the polyfunctional
carboxylic acid.
The curative is an oligomeric structure of carboxylic-acid-capped epoxidized
vegetable oil,
heretofore called a pre-polymer curative. The curative is a viscous liquid
that is soluble in
unmodified epoxidized vegetable oil and other epoxidized plant-sourced
polymers (e.g.,
epoxidized natural rubber).
Generally the terms "curative," "pre-polymer," and "pre-polymer curative" are
used to denote
the same and/or similar chemical structure as disclosed in this Section 1.
However, the
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function of the curative, pre-polymer, and pre-polymer curative may be
different in different
applications thereof to produce different end products. For example, when the
curative is
used with epoxy-containing monomeric resins (e.g., EV0s) it functions to build
molecular
weight that is integral to the backbone of the resultant polymer and therefore
may be referred
to as a pre-polymer in such applications. In another example, when the
curative is used in
applications having pre-existing high molecular weight epoxy-containing
polymer (e.g., as
disclosed below herein) the curative is functioning primarily to link those
pre-existing high
molecular weight polymers and therefore may be referred to simply as a
curative in such
applications. Finally, when the curative is used in applications having both
substantial
amounts of epoxy-containing monomer and some portion of pre-existing high
molecular
weight epoxy-containing polymer it functions both to build molecular weight
and to link pre-
existing high molecular weight polymers and therefore may be referred to as a
pre-polymer
curative.
It has been found that the creation of a curative can eliminate the risk of
porosity due to
solvent evaporation during the curing process. Furthermore, the oligomeric
curative may
incorporate substantially all of the polyfunctional carboxylic acid so that no
additional
curative is required during the curing process. For example, citric acid is
not miscible in
epoxidized soybean oil (ESO) but they may be made to react with each other in
a suitable
solvent. The amount of citric acid may be selected so that the curative is
created so that
substantially all of the epoxide groups of the ESO in the curative are reacted
with carboxylic
acid groups of the citric acid. With sufficiently excess citric acid, the pre-
polymerization
extent may be limited so that no gel fraction is formed. That is, the target
species of the
curative is a low molecular weight (oligomeric) citric-acid capped ester-
product formed by
the reaction between carboxylic acid groups on the citric acid with epoxide
groups on the
ESO. The solvent used for the reaction medium contains at least some portion
of a hydroxyl-
containing solvent (i.e., an alcohol) that is grafted unto at least some of
the polyfunctional
carboxylic acid during the creation of the curative. Although specific
illustrative
embodiments may denote one type of alcohol (e.g., IPA, ethanol, etc.), such
embodiments are
not meant to be limiting in any way unless otherwise indicated in the
following claims.
Illustrative oligomeric curatives may be created with weight ratios of ESO to
citric acid in the
range of 1.5:1 ¨ 0.5:1, which corresponds to a molar ratio of epoxide
groups:carboxylic acid
groups of approximately 0.43:1 (for a weight ratio of 1.5:1) to 0.14:1 (for
the weight ratio of
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0.5:1). In on illustrative embodiment a weight ratio of ESO:citric acid is
1:1, which gives a
molar ratio of epoxide groups:carboxylic acid groups of 0.29:1. If too much
ESO is added
during curative creation, the solution may gel and further incorporation of
ESO to create the
target resin becomes impossible. Note that on a weight basis, stoichiometric
equivalent
amounts of epoxide groups on the ESO (molecular weight of ¨1000 g/mol,
functionality of
4.5 epoxide groups per molecule) and carboxylic acid groups on the citric acid
(molecular
weight 192 g/mol, functionality of 3 carboxylic groups per molecule) occur at
a weight ratio
of 100 parts of ESO to about 30 parts of citric acid. A weight ratio of
ESO:citric acid above
1.5:1 may build a curative with excessive molecular weight (and hence
viscosity) which
limits its ability to be incorporated into unmodified epoxidized vegetable oil
or epoxidized
natural rubber. If the weight ratio of ESO:citric acid is below 0.5:1 it has
been found that
there is so much excess citric acid that after solvent evaporation, ungrafted
citric acid may
precipitate out of solution.
In addition to controlling the ratio of ESO to citric acid, through
experimentation it has been
found that selective control of the amount of alcohol used as a solvent may
also be used to
tailor the physical properties of the resulting elastomer made with the
curative. The alcohol
solvent itself is incorporated into the elastomer by forming ester linkages
with the
polyfunctional carboxylic acid. A mixture of two or more solvents may be used
to tailor the
amount of grafting of a hydroxyl-containing solvent onto the citric acid-
capped oligomeric
curative. A schematic depiction of the chemical reaction for making an
illustrative
embodiment of the curative disclosed herein is shown in FIG. 1.
For example, and without restriction or limitation, isopropyl alcohol (IPA),
ethanol, or other
suitable alcohol without limitation unless otherwise indicated in the
following claims may be
used as a component of a solvent system used to miscibilize citric acid with
ESO. IPA,
ethanol, or other suitable alcohol are capable of forming an ester linkage via
a condensation
reaction with citric acid. Since citric acid has three carboxylic acids, such
grafting reduces the
average functionality of the citric acid molecules that are reacting with the
ESO. This is
beneficial in creating an oligomeric structure that is more linear and
therefore less highly
branched. Acetone may be used as one component of a solvent system used to
miscibilize
citric acid with ESO, but unlike IPA or ethanol, acetone itself is not capable
of being grafted
onto the citric acid-capped oligomeric curative. Indeed, during creation of
the oligomeric
curative it has been found that the reactivity of the pre-polymer is
determined, in part, by the
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ratio of the alcohol to acetone that may be used to solubilize citric acid
with ESO. That is, in
reaction mixtures with the similar amounts of citric acid and ESO, a curative
created from a
solution with a relatively high ratio of alcohol to acetone creates a curative
with longer, less-
highly-branched structures than curative created from a solution with a
relatively low ratio of
alcohol to acetone under similar reaction conditions.
Generally, a curative may be adapted for use with additional unmodified
epoxidized
vegetable oil to yield a castable resin. The improved methodology disclosed by
Applicant
herein results in substantially porosity-free elastomeric products.
2. Coated Materials
A. SUMMARY
The curative as disclosed immediately above may function as a pre-polymer and
may be
mixed with additional epoxidized vegetable oil to be used as a resin which may
be applied to
various backing materials/backing layers to yield a leather-like material with
excellent tear
strength, flexibility, dimensional stability, and fabrication integrity.
Throughout this
disclosure, the terms "backing material" and "backing layer" may be used
interchangeably
depending the specific context. However, for certain articles disclosed herein
a backing
material may be comprised of a resin-impregnated backing layer. According to
one
illustrative embodiment of a coated material utilizing the pre-polymer, one
illustrative fabric
backing material/backing layer may be a woven cotton flannel (as depicted in
FIGS. 2A & 2B
and described in more detail below). If the resin is formulated to be
relatively low in
viscosity, exposed flannel may persist above the resin-coated fabric core.
This imparts a
warm texture to the surface of the article. Other fabric backing
material/backing layer may
.. include woven substrates of various kinds (e.g., plain weave, twill, sateen
weave, denim),
knitted substrates, and non-woven substrates without limitation unless
indicted in the
following claims.
In other embodiments, the resin may be coated onto a non-stick surface (e.g.,
silicone or
.. PTFE) or texture paper at a consistent layer thickness. After the film has
been coated to an
even layer, a layer of backing material may be laid on top of the liquid
resin. The liquid resin
may wick into the fabric layer (i.e., backing material) creating a permanent
bond with the
fabric during curing. The article may then be placed in an oven to complete
the cure of the
resin. Temperatures for curing may be preferably 60 C ¨ 100 C, or even more
preferably
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70 C ¨ 90 C for a duration of 4 hr ¨ 24 hr. Longer cure times are also
permissible.
Alternatively, the liquid resin may be applied onto a non-stick surface (e.g.,
silicone or PTFE)
or texture paper at a consistent layer thickness after which fabric may be
laid on top of the
liquid resin and then another non-stick surface may be laid on top of the
resin and fabric. This
assembly may be placed in a heated molding press to complete the cure. Cure
temperatures
within a press may optionally be higher than in an oven because the molding
pressure
minimizes the creation of bubbles (voids) in the final article. Cure
temperatures within a
press may be between 80 C ¨ 170 C, or even more preferably, 100 C ¨ 150 C for
a duration
of 5 minutes ¨ 60 minutes, or more preferably between 15 minutes ¨ 45 minutes.
The resin may be optically clear with a slight yellow hue. Resin that has no
pigment added
may be used to create oil-cloth like materials that allow for fabrics to be
made water resistant
and wind resistant while still allowing the fabric patterns to be visible
within the resin.
Coated fabrics made according to this embodiment may be cured either in an
oven (without
press molding) or may be cured within a heated press. Such coated fabrics may
be used for
garments, particularly for outerwear, or for waterproof accessories;
including, but not limited
to, purses, handbags, backpacks, duffle bags, luggage, briefcases, hats, and
the like.
Novel embossed items have been created using the resin described in this
disclosure in
combination with non-woven mats comprised of virgin or recycled textile
fibers. Specifically,
non-woven webs from about 7mm thick to about 20mm thick may be impregnated by
resins
prepared according to this disclosure. After impregnation, the non-woven webs
may be
pressed in a heated hydraulic press to a nominal pressure of between 10 psi ¨
250 psi, or even
more preferably between 25 psi ¨ 100 psi. The non-woven web with resin may be
pressed
between silicone release liners, one of which may have an embossing pattern
therein. The
embossing pattern may have relief characteristics of a depth between lmm ¨
6mm, or more
preferably between 2mm and 4mm in depth. When resin prepared according to this
disclosure
is further pigmented with a structural color pigment, e.g., mica pigments of
various shades ¨
many of which have pearlescent qualities ¨ and such resin is molded into a non-
woven web
with an embossing pattern, it has been found to create aesthetically pleasing
patterned
articles. The structural color has been found to preferentially align at
embossing features to
create sharp contrasts and visual depth corresponding to the embossed pattern.
Alternatively,
and without restriction unless so indicated in the following claims, mineral
pigments from
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other source rocks and processes may be included in the casting resin to
impart color to
articles made according to the present disclosure.
Resin coated fabrics made also be created according to one embodiment of the
present
disclosure using roll-to-roll processing. In a roll-to-roll process of
textured, coated fabrics,
including leather-like materials, the texture paper is often used as a carrier
film to move both
the resin and the fabric through an oven for a specific duration of time. The
resin according to
the present disclosure may require cure times that are longer than PVC or
polyurethane resins
that are currently used in the art, thus the line speeds may be
correspondingly slower or the
cure ovens may be made longer to effect a longer cure time. Vacuum degassing
of the resin
prior to casting may allow for higher temperatures to be used for curing (due
to less residual
solvent, moisture, and trapped air) that would speed up the cure time and thus
the line pull
rate.
Alternatively, certain catalysts are known in the art to speed up the
carboxylic acid addition
to epoxide groups. Base catalysts may be added to the resin; some example
catalysts include
pyridine, isoquinoline, quinoline, N,N-dimethylcyclohexylamine, tributylamine,
N-
ethylmorpholine, dimethylaniline, tetrabutyl ammonium hydroxide, and similar
molecules.
Other quaternary ammonium and phosphonium molecules are known catalysts for
the
carboxylic acid addition to epoxide groups. Various imidazoles are likewise
known as
catalysts for this reaction. Zinc salts of organic acids are known to improve
the cure rate as
well as impart beneficial properties, including improved moisture resistance,
to the cured
films. (See Werner J. Blank, Z. A. He and Marie Picci, "Catalysis of the Epoxy-
Carboxyl
Reaction", Presented at the International Waterborne, High-Solids and Powder
Coatings
.. Symposium, February 21-23, 2001.) Accordingly, any suitable catalyst may be
used without
limitation unless otherwise indicated in the following claims.
B. ILLUSTRATIVE EMBODIMENTS
Although the illustrative embodiments and methods that follow include specific
reaction
parameters (e.g., temperatures, pressures, reagent ratios, etc.), those
embodiments and
methods are for illustrative purposes only and in no way limit the scope of
the present
disclosure unless otherwise indicated in the following claims.
First Illustrative Embodiment and Method
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To make a first illustrative embodiment of a coated material using the pre-
polymer (that is,
the curative as disclosed previously above), 18 parts of citric acid were
dissolved into 54
parts of warm IPA. To this solution, only 12 parts of ESO is added. The IPA
was evaporated
with continuous heating and stirring (above ¨85 C). This was found to make a
viscous liquid
that could be heated to above 120 C without gelation (even for long periods of
time). This
viscous liquid pre-polymer was allowed to cool below 80 C. To this viscous
liquid, 88 parts
of ESO is added. The final liquid resin will polymerize to a solid elastomeric
product in 1-5
minutes at ¨150 C. The coated material (which may serve as a substitute for
natural animal-
hide leather) may be formed as a reaction product using an epoxidized
triglyceride and the
pre-polymer without limitation unless otherwise indicated in the following
claims.
Second Illustrative Embodiment and Method
For this illustrative embodiment, 30 parts of citric acid were dissolved into
60 parts of warm
IPA. To this solution, 20 parts of ESO were slowly added while stirring. The
IPA was
evaporated with continuous heating and stirring (above 85 C, and preferably
above 100 C).
This viscous pre-polymer was allowed to cool below 80 C (preferably below 70
C) and 80
parts of ESO were added along with various structural color pigments and 0.5
parts of zinc
stearate (as an internal mold release agent). The resulting resin was poured
over cellulosic
fabric and allowed to cure at ¨120 C for 10-30 minutes. After initial cure,
the material was
placed in an 80 C oven for overnight post-curing (-16 hours). The surface of
the material
was then sanded smooth (and optionally polished). The resulting material was
found to have
leather-like attributes.
Third Illustrative Embodiment and Method
Pre-polymer creation has been conducted by dissolving 50 parts of citric acid
in 100 parts of
warm IPA, accelerated by mixing. After dissolution of the citric acid, 50
parts of ESO is
added to the stirring solution. The mixture is kept on a hot plate while the
IPA evaporated
under continuous heat and stirring. Such solutions have been created multiple
times with
various hot plate temperatures and air flow conditions. Even after extended
times of heating
and stirring, it has repeatedly been found that the amount of reaction product
is greater than
the mass of the ESO and citric acid alone. Depending on the rate of IPA
evaporation
(determined at least by air flow, mixing rate, and hot plate temperature)
between 2.5 and 20
parts of the IPA has been found to be grafted onto the citric-acid capped
oligomeric pre-
polymer. Furthermore, solvent blends of acetone and IPA may be used as the
reaction
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medium wherein the ratio between acetone and IPA determines the amount of
residual
carboxylic acid functional groups on the pre-polymer as well as the amount of
branching in
the pre-polymer. Higher amounts of IPA create more linear structures by
lowering the
effective functionality of the citric acid by capping some of the carboxylic
acid functional
groups by grafting IPA unto the citric acid via an ester linkage as referenced
in FIG. 1. Lower
amounts of IPA create more highly branched structures with more residual
carboxylic acid
functional groups.
Fourth Illustrative Embodiment and Method
Pre-polymer creation has been conducted by dissolving 50 parts of citric acid
in 100 parts of
warm IPA, accelerated by mixing. After dissolution of the citric acid, 50
parts of ESO and 15
parts of dewaxed blonde shellac is added to the stirring solution. The mixture
is kept on a hot
plate the while IPA evaporated under continuous heat and stirring. The shellac
was found to
increase the viscosity of the resulting pre-polymer.
Fifth Illustrative Embodiment and Method
Pre-polymer creation has been conducted by dissolving 45 parts of citric acid
in 90 parts of
warm IPA, accelerated by mixing. After dissolution of the citric acid, 45
parts of ESO is
added to the stirring solution. The mixture is kept on a hot plate while the
IPA evaporated
under continuous heat and stirring.
Sixth Illustrative Embodiment and Method
Pre-polymer creation has been conducted by dissolving 45 parts of citric acid
in 30 parts of
warm IPA and 60 parts of acetone, accelerated by mixing. After dissolution of
the citric acid,
45 parts of ESO is added to the stirring solution. The mixture is kept on a
hot plate while the
acetone and IPA evaporated under continuous heat and stirring. Such solutions
have been
created multiple times with various hot plate temperatures and air flow
conditions. Even after
extended times of heating and stirring, it has repeatedly been found that the
amount of
reaction product is greater than the mass of the ESO and citric acid alone,
but the amount of
grafted IPA is less than in pre-polymer created according to the fifth
illustrative embodiment
(even though the ratio of ESO:citric acid is 1:1 in both cases). Furthermore,
pre-polymer
created according to the fifth illustrative embodiment is lower in viscosity
compared to pre-
polymer created according to the sixth illustrative embodiment.
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Generally, it is contemplated that the greater content of IPA during the pre-
polymer creation
allowed more IPA to be grafted onto carboxylic-acid sites on the citric acid,
thus lowering the
average functionality of the citric acid and thus creating a less highly
branched oligomeric
pre-polymer. In no circumstance have reaction conditions been found that
capping of the
citric acid with IPA to such an extent that final curing of the resin is
prohibited.
Seventh Illustrative Embodiment and Method
The pre-polymer created in the fourth illustrative embodiment was mixed with
additional
ESO to bring the total calculated amount of ESO to 100 parts. This mixture was
found to cure
into a transparent, elastomeric resin. Tensile testing according to ASTM D412
found that the
tensile strength was 1.0 MPa with an elongation at break of 116%.
Eight Illustrative Embodiment and Method
Pre-polymer was created by dissolving 45 parts of citric acid in 20 parts of
IPA and 80 parts
of acetone under heating and stirring. After dissolution of the citric acid,
35 parts of ESO was
added to the solution along with 10 parts of shellac. The pre-polymer created
after
evaporation of the solvents was then cooled. The pre-polymer was mixed with an
additional
65 parts of ESO to bring the total amount of ESO to 100 parts. The mixed resin
was then cast
on a silicone mat to make a transparent sheet. The mechanical properties of
the material were
found by tensile testing according to ASTM D412. The tensile strength was
found to be 1.0
MPa and the elongation was 104%, which gives a calculated modulus of 0.96 MPa.
Ninth Illustrative Embodiment and Method
Pre-polymer was created by dissolving 45 parts of citric acid in 5 parts of
IPA and 80 parts of
acetone under heating and stirring. After dissolution of the citric acid, 35
parts of ESO was
added to the solution along with 10 parts of shellac. The pre-polymer created
after
evaporation of the solvents was then cooled. The pre-polymer was mixed with an
additional
65 parts of ESO to bring the total amount of ESO to 100 parts. The mixed resin
was then cast
on a silicone mat to make a transparent sheet. The mechanical properties of
the material were
found by tensile testing according to ASTM D412. The tensile strength was
found to be 1.8
MPa and the elongation was 62%, which gives a calculated modulus of 2.9 MPa.
As can be
seen from the eighth and ninth illustrative embodiments, the lower amount of
IPA present
during pre-polymer creation yields a pre-polymer that creates a more highly
crosslinked resin
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with higher modulus and lower elongation. These reaction products are more
plastic-like and
less rubber-like in their material attributes.
Tenth Illustrative Embodiment and Method
Pre-polymer was created by dissolving 25 parts of citric acid in 10 parts of
IPA and 80 parts
of acetone under heating and stirring. After dissolution of the citric acid,
20 parts of ESO was
added to the solution along with 5 parts of shellac. The pre-polymer created
after evaporation
of the solvents was then cooled. The pre-polymer was mixed with an additional
80 parts of
ESO to bring the total amount of ESO to 100 parts. The mixed resin was then
cast on a
silicone mat to make a transparent sheet. The mechanical properties of the
material were
found by tensile testing according to ASTM D412. The tensile strength was
found to be 11.3
MPa and the elongation was 33%, which gives a calculated modulus of 34 MPa. As
can be
seen from the tenth illustrative embodiment, by appropriate design of the pre-
polymer and the
final resin mixture, a plastic material with the attributes of high strength
and high modulus
may be created by the methods of the present disclosure.
Eleventh Illustrative Embodiment and Method
The pre-polymer of the sixth illustrative embodiment was mixed with additional
ESO to
bring the total calculated amount of ESO to 100 parts. The mixed resin was
then cast on a
silicone mat to make a transparent sheet. The mechanical properties of the
material were
found by tensile testing according to ASTM D412. The tensile strength was
found to be 0.4
MPa and the elongation was 145%, which gives a calculated modulus of 0.28 MPa.
As can be seen from the eleventh illustrative embodiment, by appropriate
design of the pre-
polymer and the final resin mixture, a high elongation elastomeric material by
be created by
the methods of the present disclosure. Therefore, by appropriate design of the
pre-polymer,
the inventive methods may be used to produce materials ranging from stiff,
plastic-like
materials to high-elongation elastomeric materials. Generally, higher amounts
of IPA grafted
during pre-polymer formation lowers the stiffness of the resulting material.
Higher amounts
of dissolved shellac yield stronger materials with somewhat higher stiffness.
Citric acid
amount (relative to the final mixed recipe) may be used either above
stoichiometric balance
or below to lower the modulus. Citric acid amounts near stoichiometric balance
(-30 parts by
weight to 100 parts by weight ESO) generally yield the stiffest materials;
unless offset by
high levels IPA grafting of the carboxylic acid groups during pre-polymer
formation.
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One of the beneficial attributes of animal-based leather is its flexibility
over a wide range of
temperatures. Synthetic-polymer based leather substitutes based on PVC or
polyurethane may
become particularly stiff at temperatures below -10 C or below -20 C (based on
testing
__ according to CFFA-6a ¨ Cold Crack Resistance ¨ Roller method). Materials
prepared
according to some of the embodiments of the present disclosure may have poor
cold crack
resistance. In the following examples, formulations are given that improve
cold crack
resistance. Cold crack resistance may be improved by adding a flexible
plasticizer. Some
natural vegetable oils may exhibit good low temperature flow, especially
preferred may be
polyunsaturated oils. Such oils may be any non-epoxidized triglycerides (such
as those
disclosed in Section 1 above) having relatively high iodine numbers (e.g.,
greater than 100)
without limitation unless otherwise indicated in the following claims.
Alternatively,
monounsaturated oils may be added as plasticizers; one illustrative oil may be
castor oil
which is found to be thermally stable and less prone to becoming rancid.
Additionally, the
fatty acids and fatty acid salts of these oils may be used as a plasticizer.
Accordingly, the
scope of the present disclosure is in no way limited by the presence of or
particular chemistry
of a plasticizer unless otherwise indicated in the following claims.
Another approach is to use a polymeric additive that may impart improved low
temperature
flexibility. A preferred polymeric additive may be Epoxidized Natural Rubber
(ENR). ENR is
available commercially in different grades with various levels of epoxidation,
for example
25% epoxidation of the double bonds yields grade ENR-25, 50% epoxidation of
the double
bonds yields grade ENR-50. Higher levels of epoxidation increase the glass
transition
temperature, Tg. It is advantageous for the Tg to remain as low as possible
for the most
improvement in cold crack resistance in the final resin, so ENR-25 may be the
preferred
grade for use as a polymeric plasticizer. Even lower levels of epoxidation may
be
advantageous for further lowering of the cold crack temperature in the final
resin. However,
the scope of the present disclosure is not so limited unless otherwise
indicated in the
following claims.
Twelfth Illustrative Embodiment and Method
ENR-25 was mixed with ESO on a two-roll rubber compounding mill. It was found
that ESO
could slowly be added until a total of 50 parts of ESO could be added to 100
parts of ENR-25
before the viscosity dropped so far that further mill mixing was impossible.
This gooey
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material was then transferred to containers for further mixing in a Flacktek0
Speedmixer. A
flowable mixture was achieved when a total of 300 parts of ESO was finally
incorporated
into 100 parts of ENR-25. The mixture created did not phase segregate.
The material of the twelfth illustrative embodiment may be mixed in a single
step by a
number of means known in the art, without restriction or limitation unless
indicated in the
following claims. Specifically, so-called Sigma Blade mixers may be used to
create a
homogenous mixture of ENR and ESO in a single step. Likewise, a kneader, such
as a Buss
Kneader, by used to create such mixtures in a continuous mixer-type
arrangement which is
well known to one of ordinary skill in the art. The homogeneous mixture may be
mixed with
pre-polymers as described in prior examples to create a spreadable resin that
may be used as a
leather-like material with improved cold crack resistance. Additionally,
materials created
with ENR-modified ESO as disclosed by the twelfth illustrative embodiment may
exhibit
improved tear strength, elongation, and abrasion resistance when compared to
resins that do
not contain ENR.
C. Additional Treatments
Articles produced according to this disclosure may be finished by any means
known in the
art. Such means include, but are not limited to, embossing, branding, sanding,
abrading,
polishing, calendering, varnishing, waxing, dyeing, pigmenting, and the like
unless otherwise
indicated in the following claims. Exemplary results may be obtained by
impregnating the
resin of the present disclosure onto fabric or a non-woven mat and curing such
article. After
curing the article, the surfaces may be sanded to remove imperfections and
expose some
portion of the substrate. Such surfaces exhibit characteristics very analogous
to animal-hide
leather, as exemplified by FIGS. 3-7. The surfaces then may be treated with
natural oil or
wax protectants, subject to a particular application.
D. Applications/Illustrative Products
Coated fabrics, ENR-based materials, and/or oil cloth-like materials produced
according to
the present disclosure may be used in applications where animal-hide leather
and/or synthetic
resin-coated fabrics are used today. Such applications may include belts,
purses, backpacks,
shoes, table tops, seating, and the like without limitation unless otherwise
indicated in the
following claims. Many of these articles are consumable items that if made
from synthetic
material alternatives are non-biodegradable and are non-recyclable. If such
items are instead
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made according to the present disclosure, they would be biodegradable and thus
not create a
disposal problem as the biodegradability of similarly prepared polymers made
from ESO and
natural acids has been studied and shown. Shogren et al., Journal of Polymers
and the
Environment, Vol. 12, No. 3, July 2004. Furthermore, unlike animal-hide
leather, which
requires significant processing to be made durable and stable (some of which
uses toxic
chemicals), the materials disclosed herein may require less processing and
will use
environmentally friendly chemicals. Additionally, animal-hide leather is
limited in size and
may contain defects that render large pieces inefficient to produce. The
material disclosed
herein does not have the same kind of size limitations.
A cross-sectional depiction of the resulting material when a liquid resin
precursor such as
those described for various illustrative embodiments and methods above was
applied to
cotton flannel fabric that was placed over a heated surface (a hot plate) is
shown in FIGS. 2A
& 2B. The resin was found to react in 1-5 minutes when the surface temperature
of the hot
plate was ¨130 C-150 C. The viscosity of the resin may be controlled by the
time allowed
for polymerization prior to pouring over the surface. By controlling the
viscosity, the degree
of penetration into the surface may be controlled to achieve various effects
in the resultant
product. For example, a lower viscosity resin may penetrate throughout the
fabric 102 and
leave a suede or brushed-looking surface as shown in FIG. 2A to create a
natural leather-like
material 100 having a suede finish. A higher viscosity resin may penetrate
only partly
through the fabric 102 and result in a glossy, polished-looking surface as
shown in FIG. 2B to
create a natural leather-like material 100' having a glossy finish. In this
way, variations may
be created that mimic natural animal-hide leather products. As shown in
contrasting FIGS.
2A & 2B, the natural leather-like material 100 having a suede finish 100 may
exhibit a larger
number of fabric extensions 103 extending from the fabric 102 through the
polymer 104 than
does the natural leather-like material 100' having a glossy finish. In the
natural leather-like
material 100' having a glossy finish, the majority of fabric extensions 103
may terminate
within the polymer 104.
Alternatively, an article with a suede-like (i.e., relatively soft) surface
without resin may be
created by embedding flannel in a non-miscible paste (e.g., silicone vacuum
grease) that is
coated on a hot plate. The resin can then be poured over the surface of the
flannel but will not
penetrate through the non-miscible paste. After curing, the non-miscible paste
may be
removed from the article leaving that surface with a suede-like feeling. One
of ordinary skill
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will therefore appreciate that a natural leather-like material as disclosed
herein may be
produced as the reaction product between an epoxidized vegetable oil and a
naturally
occurring polyfunctional acid impregnated upon a cotton flannel substrate,
without limitation
or restriction, wherein the article thus formed has the reaction product
impregnated only
partly through the substrate with substantially unimpregnated flannel on one
side of the
article. Although cotton flannel was used in these examples, any suitable
flannel and/or fabric
may be used including but not limited to those made from linen, hemp, ramie,
and other
cellulosic fibers without limitation unless otherwise indicated in the
following claims.
Additionally, non-woven substrates may be used as well recycled substrates
(upcycled).
Brushed knits may be used to impart additional stretch to the resultant
article. Random mats
(e.g., Pellon, also known as batting) may be advantageously used as a
substrate for certain
articles. In another illustrative embodiment, a textile backing layer and/or
backing material
may be configured from a protein-based fiber, which fibers include but are not
limited to of
wool, silk, alpaca fiber, qiviut, vicuna fiber, llama wool, cashmere, and
angora unless
otherwise indicated in the following claims.
Additional illustrative products that may be made according to the present
disclosure are
shown in FIGS. 3-8B. A depiction of a sheet of material that may serve as a
natural leather-
like material is shown in FIG. 3, and FIGS. 4-6 show various natural leather-
like materials
that may be used to construct a wallet. The material in FIGS. 4A, 4B, & 4C is
shown with a
plurality of apertures made therein, which apertures may be made with a
conventional drill
without limitation unless otherwise indicated in the following claims.
Contrasting FIGS. 4A,
4B, & 4C shows that the method for making the material may be configured to
impart a wide
variety of textures thereon, which textures include but are not limited to
smooth, grainy, soft,
etc. (e.g., similar to that of various animal-hide leathers) unless otherwise
indicated in the
following claims.
The material pieces shown in FIGS. 5 & 6 may be cut using a laser cutter.
Unlike animal-hide
leather, the laser cutting did not char or degrade the edges of the natural
leather-like material
along the cutline. A finished wallet constructed of a natural leather-like
material made
according to the present disclosure is shown in FIG. 6. The separate pieces
shown in FIG. 5
may be conventionally assembled (e.g., sewn) to construct a simple credit card
wallet or
carrier (as shown in FIG. 6) having the appearance, rigidity, and strength as
one would expect
in a similar article made from animal-hide leather. The natural leather-like
material may be
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sewn and/or otherwise processed into a finished product using conventional
techniques
without limitation unless otherwise indicated in the following claims. As
shown in FIG. 7 and
as described in detail above, a fabric may be impregnated with a resin to
provide various
characteristics to an article made according to the present disclosure.
Additionally, the resin produced according to the present disclosure may be
pigmented to
match the coloration of natural animal-hide leather. Of particular utility are
structural color
pigments and/or mineral pigments that do not contain any harmful substances.
One such
example of illustrative structural color pigments is Jaquard PearlEx0
pigments. It has been
found that the blending of structural color pigments at relatively low
loadings creates a
natural leather-like material that has excellent visual aesthetics. Another
such illustrative
example of a suitable pigment may be procured from Kreidezeit Naturfarben,
GmbH.
Furthermore, it has been found that lightly sanding the resultant surface
results in a material
that strongly resembles tanned & dyed animal-hide leather.
Although certain examples disclosed herein may be configured to utilize only
one layer of
fabric, other illustrative samples have been created with multiple fabric
layers to create
thicker leather-like products. Since the reaction between epoxide groups and
carboxylic
groups does not create any condensation by-products, there is no inherent
limit to the cross-
sectional thickness that may be created. Generally, resin-coated fabrics and
non-wovens are
used in applications such as office furniture, including seating, writing
surfaces, and room
dividers; in garments, including jackets, shoes, and belts; in accessory
items, including
handbags, purses, luggage, hats, and wallets; and may be useful in residential
decorations,
including wallcoverings, floor coverings, furniture surfaces, and window
treatments.
Materials made according to the present disclosure may be used in any of those
applications
or other applications disclosed herein or later occurring depending on the
suitability of the
material without limitation unless otherwise indicated in the following
claims. Additionally,
current applications that are served by animal-based leather may be considered
potential
applications for materials made according to the present disclosure.
Furthermore, current applications that are served by petrochemical-based
flexible films;
notably those served by PVC and polyurethane-coated fabrics, may be considered
potential
applications for materials made according to the present disclosure. In
addition, the resin as
disclosed herein is substantially free of any off-gassing vapors when cured
according to the
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times and temperatures as disclosed herein. Therefore, applications that are
thicker than
traditional films may also be served by the resins prepared according to the
present
disclosure. For example, the resin may be used to cast three-dimensional items
in suitable
molds. A top view of such a three-dimensional item configured as a ball made
according to
the present disclosure is provided in FIG. 8A, and a side view thereof is
shown in FIG. 8B.
The ball may be resin-based and may be produced from epoxidized soy oil and
citric acid-
based recipes along with structural color pigments. Simple tests indicate it
has very low
rebound and is expected to have excellent vibration absorption qualities.
Prior art three-dimensional cast resin items are typically made of styrene-
extended polyester
(orthophthallic or isophthalic systems). Such items may currently consist of
two-part epoxies
or two-part polyurethane resins. Such items may currently consist of silicone
casting resins.
One example of an application currently served by two-part epoxies is the
thick-film coating
of tables and decorative inlays, wherein the epoxy may be selectively
pigmented to create a
pleasing aesthetic design. Such applications have been successfully duplicated
with casting
resins created according to the present disclosure. Furthermore, small chess
pieces have been
successfully cast from resins created according to the present disclosure
without detrimental
off-gassing or trapped air. Accordingly, a wide array of applications exist
for various
materials made according to the present disclosure and the specific intended
use of the final
article produced by any method disclosed herein is not limited to a particular
application
unless otherwise indicated in the following claims.
E. RESINOUS COATINGS, PRODUCTS, AND METHODS
In various illustrative embodiments disclosed herein, natural products may
have physical
properties similar to synthetic coated fabrics, animal-based leather products,
and foam
products. As disclosed the physical properties of the natural products may be
further
enhanced to improve flexibility.
Background
Coatings are present on many consumer goods where such coatings are applied to
provide
surface protection and/or coloration. In addition, in some consumer goods, the
coating may
serve primarily to improve the haptics (that is, the tactile feel) of a
surface. In one class of
materials, namely animal-based leather and leather-like materials, surface
coatings may be
provided to provide surface protection, coloration, and improved haptics. For
animal-based
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leather, such coatings may be substantially absorbed into the substrate and
complement the
natural haptics of the leather. Such coatings may be based on oils, waxes,
and/or polymers
(both natural and synthetic). In the creation of petrochemical-based leather
alternatives (e.g.,
those based on PVC or PU), coatings may or may not be required, but when used,
they are
generally also petrochemical-based. In the development of a non-petrochemical
and non-
animal-based leather alternative, that is a material based entirely on plant-
derived ingredients,
it may also be desired to provide a coating that provides additional surface
protection,
coloration, and/or improved haptics to the non-petrochemical and non-animal-
based leather
alternative.
Summary
Generally, an illustrative embodiment of a coating may be created entirely
from plant-derived
ingredients. This coating may be particularly well suited for use on leather-
like materials
created from epoxidized natural rubber-based formulations but is not so
limited unless
otherwise indicated in the following claims. The coating created according to
the present
disclosure may be configured as substantially the reaction product between
epoxidized
vegetable oil and a polyfunctional naturally occurring acid (such as citric
acid) as further
disclosed in U.S. Patent #10,400,061. The coating has been found to greatly
improve the
haptics of the products thus coated.
Illustrative embodiments and detailed description
Animal-based leather materials exhibit a haptic quality that is particularly
smooth to the
touch, even for textured articles. It has been found that the relationship
between the dynamic
coefficient of friction and static (or "breakaway") coefficient of friction is
key to quantifying
this attribute. In generally, rubbery materials tend to have high grip, which
may be reflected
in both the actual values of the coefficients of friction (static and
dynamic), while the static
coefficient of friction is generally significantly higher than the dynamic
coefficient of
friction.
Certain leather-like materials (which are substitutes for animal-based
leather) have been
found to exhibit characteristic rubber-like coefficient-of-friction values;
especially when such
materials are formulated with epoxidized natural rubber (ENR). Formulations
based on ENR
with a 25% epoxidation level tend to have higher friction than formulations
based on ENR
with a 50% epoxidation level. This is consistent with polymer theory that
correlates the glass
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transition temperature (Tg) with the coefficient of friction. That is, higher
Tg results in lower
coefficient of friction while lower Tg results in higher coefficient of
friction. It has been
documented that roughly each increased percentage change in epoxidation degree
increases
the Tg by one degree Celsius. The coefficient of friction effect of changes in
Tg is due to the
rate at which polymer chains can rearrange to engage the contacting surface.
Unfortunately,
many consumer goods require a material with a low Tg to prevent articles from
becoming
stiff or brittle at reduced ambient temperatures (as may be encountered in the
winter). Thus,
the Tg of the material formulated for low temperature flexibility (based on
ENR with lower
epoxidation levels) tends to make the material more grippy, which negatively
impacts the
haptics of an article.
Therefore, it is desired to have an article construction that has a base
material with a low Tg
and a coating with a relatively higher Tg while the coating ought to retain
enough flexibility
to avoid cracking at low temperatures. Additionally, testing the coefficient
of friction in such
a way that captures data consistent with what is observed with human hands is
challenging.
Generally, tests between animal-based leather and stainless-steel sheets and
between animal-
based leather and silicone sheets give data that does not correlate with the
order of magnitude
in coefficient of friction (COF) that a human hand would detect. In contrast,
testing animal-
based leather against a PTFE-coated-fiberglass baking sheet shows similar
static and dynamic
coefficients of friction while also giving a relatively low absolute value
that reflects the
feeling of the human hand. Taking that same test method and applying it to
materials
produced according to various methods disclosed in U.S. Patent #10,400,061
gives the data
shown in Table 1.
Test material Counter-surface Dynamic COF Static COF
Resin-coated plant-based PTFE Coated
leather Fiberglass 0.15 0.59
Uncoated plant-based PTFE Coated
leather based on ENR Fiberglass 0.44 0.46
PTFE Coated
Red Leather - Smooth Front Fiberglass 0.17 0.17
Table 1¨Test results for an animal-based leather and two leather-like
materials.
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From Table 1 we see that animal-based leather has a low static and dynamic COF
while an
uncoated plant-based leather material based on ENR has a relatively higher
COF. In the first
row we see data that coating such material with resin that is a reaction
product between
epoxidized soybean oil (ESO) and citric acid (various illustrative embodiments
of which may
be produced by methods disclosed in US 10,400,061) lowers the dynamic COF to a
value
closer to animal-based leather. This results in a haptic quality that is
considerably improved
when compared to the uncoated ENR-based leather-like material.
Specifically, the coating used for resin-coated plant-based leather in Table 1
may be
formulated by making a curative as disclosed in US 10,400,061 and then mixing
that curative
with additional ESO to make a temperature-curable resin. In the first stage of
curative
manufacture, citric acid is dissolved in isopropyl alcohol, ethanol, or a
combination of
acetone and alcohol-containing solvent. In the second stage of curative
manufacture ESO or
similar epoxy-containing plant-based triglyceride oil is added to the
dissolved citric acid
solution and allowed to react while simultaneously removing the miscibilizing
solvent. An
illustrative curative formulation may use 50 parts of citric acid to 50 parts
of ESO to 400
parts of miscibilizing solvent. After the curative has been formed and the
miscibilizing
solvent evaporated, then roughly 100 parts of curative is mixed with another
100 parts of
ESO to make the coating resin. Such coating resin may be further diluted with
solvent to
make it easier to spray or spread. An example dilution for easy spreading may
entail mixing
the resin with an equal mass of isopropyl alcohol, ethanol, or acetone.
Subsequently, the
dilution solvent is allowed to evaporate, and the resin-coated substrate may
be placed into an
oven or a heated press to complete the curing reaction between the curative
and the
epoxidized plant-based triglyceride oil. In one illustrative embodiment, the
coating resin may
require 10 minutes to cure at 150 C. The texture of the coating resin may be
determined by
textured release paper or textured silicone sheets to give the desired
appearance and haptics
without limitation unless otherwise indicated in the following claims.
Another illustrative embodiment of a coating configured according to the
methods disclosed
herein is comprised of a resin coating formulation that may be produced based
on the ratio of
100 parts of curative with 100 parts of ESO, which may be further modified for
easy
application. Specifically, such mixture may be diluted with acetone, isopropyl
alcohol, or
ethanol at a ratio of 1:1 (mixed resin:solvent) up to 1:20 (mixed
resin:solvent). Generally, any
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chemically suitable solvent having a boil point from approximately 55 degrees
Celsius to
approximately 85 degrees Celsius may be used with various illustrative
embodiments of a
coating without limitation unless otherwise indicated in the following claims.
Thinner
dilutions may enable easy spraying of thin coatings while thicker dilutions
may be more
appropriate for roll-coating. In another illustrative embodiment, it has been
found that the
inclusion of a thickening polymer may aid in both the haptics of the cured
film and in
preventing the resin from squeezing out during the molding step. Such
thickening polymers
may include, but are not limited to unless otherwise indicated in the
following claims,
shellac, cellulose acetate, cellulose acetate phthalate, hydroxypropyl
cellulose, and other
naturally occurring or naturally derived polymers (without limitation unless
otherwise
indicated in the following claims) that are soluble in acetone, isopropyl
alcohol, ethanol, or
other suitable solvent without limitation unless otherwise indicated in the
following claims.
Generally, any thickener having the desired effect on the coating during use
for its intended
application may be used to create an illustrative embodiment of the coating
disclosed herein
without limitation unless otherwise indicated in the following claims.
Release additives such as waxes may be included in the resin coating to
improve haptics and
help release from texture paper. In one illustrative embodiment olive wax has
been found to
be particularly advantageous for such purposes. In other illustrative
embodiments as
disclosed herein, ultra-violet (UV) light stabilizing additives such as micro-
TiO2 or nano-
TiO2 may be added to improve the light stability of the coating and protect
the underlying
material, without departure from spirit of this disclosure and without
limitation unless
otherwise indicated in the following claims.
It has been found that curing said coating resin by molding it between an ENR-
based rubber
substrate as disclosed in US 10,400,061 and textured silicone or texture paper
yields and
appearance and haptic quality that are particularly well suited for consumer
goods that
require low dynamic COF, low gloss, and a "dry" hand.
It is generally understood that the Tg of materials correlates to the COF and
the resin coating
as disclosed herein has a Tg higher than epoxidized natural rubber, even at
the 50%
epoxidation level. Furthermore, the resin coating may have a relatively higher
crosslink
density and thus may exhibit less conformability to the human hand. These
attributes may
contribute to the preferred "hand" of the material.
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Industrial applicability
Various illustrative embodiments of resin coatings as disclosed herein may be
particularly
suited to coating ENR-based rubber substrates as may be used in wallets,
handbags, purses,
.. shoes, belts, and similar consumer items that may be normally made of
leather or PU/PVC
faux leather without limitation unless otherwise indicated in the following
claims. Illustrative
embodiments of a coating disclosed herein may be particularly advantageous in
being used to
coat ENR-based rubber because of the inherent material compatibility between
coating and
substrate. For example, and without limitation unless otherwise indicated in
the following
claims, it has been found that thin coatings (e.g., less than 200 microns) as
applied using
textured silicone or texture paper are flexible enough to withstand bending at
-15 C without
delamination or cracking; whereas such coating materials when subject to
bending at low
temperatures as a bulk material (thickness greater than 500 microns) are prone
to cracking.
.. Untextured oven-curing such coatings may result in a glossy surface that
has less desirable
haptics when compared to press-cured and textured coatings. In some
illustrative
embodiments, the press-curing of the coating may occur concurrently with the
curing of the
substrate ENR-based rubber material. In other illustrative embodiments, the
substrate may be
cured in a first step, the coating applied in a second step, and the coating
cured against
textured silicone or texture paper in a third step.
In other illustrative embodiments, the resin coating may be applied directly
to fabrics to
provide water resistance. In such illustrative embodiments, a higher dilution
level of the
coating solution (e.g., ¨3-6% solids) may yield a fabric with water resistance
while retaining
the flexible hand of the fabric. Higher solids contents may yield more barrier
resistance with
a stiffening of the substrate.
Materials made and/or coated according to any teaching of this disclosure may
be used as
flooring, exercise mats, bedding, shoe insoles, shoe outsoles, or sound
absorption panels
.. without limitation unless otherwise indicated in the following claims.
Materials made and/or coated according to any teaching of this disclosure may
be molded
into complex three-dimensional articles and multi-laminated articles. Three-
dimensional
articles may also consist of multiple material formulations arranged at
various locations
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within an article to provide functionality required for each location.
The resilient memory foam based on vegetable oil may be used in applications
where
polyurethane is used today. Such applications may include shoes, seating,
flooring, exercise
.. mats, bedding, sound absorption panels, and the like without limitation
unless otherwise
indicated in the following claims. Many of these articles are consumable items
that if made
from synthetic polyurethane foams are non-biodegradable and are non-
recyclable. If such
items are made from the material disclosed herein, they would be biodegradable
and thus not
create a disposal problem.
Although the methods described and disclosed herein may be configured to
utilize a coating
comprised of a natural materials, the scope of the present disclosure, any
discrete process step
and/or parameters therefor, and/or any apparatus for use therewith is not so
limited and
extends to any beneficial and/or advantageous use thereof without limitation
unless so
.. indicated in the following claims.
3. Epoxidized Rubber
A. Summary
Coated fabrics prepared as disclosed in Section 2 above use a liquidous
viscosity resin that
allows such materials to flow into fabric and non-woven substrates. The
resulting cured
materials have mechanical properties that reflect highly-branched structures
with limited
polymer flexibility between crosslinks (modest strength and modest
elongation). One means
of increasing the mechanical properties is to begin with polymeric materials
that have more
linear structures and can be cured with lower cross-link density. The
incorporation of shellac
resin (which is a high molecular weight natural resin) in coated fabric
recipes was found to
improve strength and elongation but was also found to make the materials more
plastic.
Material formulations as disclosed in Section 3 ¨ Epoxidized Rubber are able
to exhibit
excellent mechanical properties (very high strength and higher elongation)
without
compromising material flexibility at room temperature (e.g., ¨15 C-30 C).
A natural material based on epoxidized natural rubber (ENR) is disclosed that
contains no
animal-based substances and is substantially free of petrochemical-containing
materials. In
certain embodiments this natural material may serve as a leather-like material
(which may be
a substitute for animal-hide leather and/or petrochemical-based leather-like
products (e.g.,
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PVC, polyurethane, etc.) without limitation unless otherwise indicated in the
following
claims. Furthermore, the natural material based on ENR as disclosed herein may
be
configured to be substantially free of allergens that may cause sensitivity in
certain people.
The material disclosed herein is more cost effective and scalable than other
proposed
materials for petrochemical-free vegan leather. With certain treatments the
natural material
may also be made water resistant, heat resistant, and retain flexibility at
low temperatures.
This set of beneficial attributes may apply to any natural material based on
ENR that is
produced according to the present disclosure and to which additional
treatments are applied,
as suitable to a particular application, as disclosed and discussed herein.
In at least one embodiment, an elastomeric material may be formed to include
at least a
primary polymeric material further comprised of epoxidized natural rubber and
a curative
comprised of a reaction product between a polyfunctional carboxylic acid and
an epoxidized
vegetable oil as disclosed in Section 1 - Curative. The elastomeric material
may also be
formed wherein the primary polymeric material is greater in volumetric
proportion in
comparison to the curative. The elastomeric material may also be formed to
wherein the
epoxidized natural rubber has a degree of epoxidation between 3% and 50%
without
limitation unless otherwise indicated in the following claims. Another
embodiment of the
elastomeric material may be comprised of a primary polymeric material
comprised of
epoxidized natural rubber and a cure system that is not sulfur-based nor
peroxide-based, and
wherein the cure system contains over 90% reactants from biological sources.
In another embodiment, an article may be formed from the reaction product of
epoxidized
natural rubber and a curative wherein the curative is the reaction product
between a naturally
occurring polyfunctional carboxylic acid and an epoxidized vegetable oil. In
another
embodiment, an article comprised of epoxidized natural rubber with fillers
including cork
powder and precipitated silica may be formed and the article may be molded as
a sheet with
leather-like texture. In another embodiment, an article may be formed wherein
the reaction
product further contains fillers of cork powder and silica. In another
embodiment, the article
may be formed or configured such that two or more layers of the reaction
product have
substantially different mechanical properties and the mechanical property
differences are due
to differences in filler composition.
B. Illustrative Methods and Products
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Epoxidized natural rubber (ENR) is a commercially available product under the
tradename
Epoxyprene0 (Sanyo Corp.). It is available in two grades with 25% epoxidation
and 50%
epoxidation, ENR-25 and ENR-50 respectively. However, in certain embodiments
it is
contemplated that an ENR with a level of epoxidation between 3% and 50% may be
used
without limitation unless otherwise indicated in the following claims. One of
ordinary skill
will appreciate that ENR may also be produced from protein denatured or
removed latex
starting products. During the epoxidation of natural rubber, it has been found
that the allergen
activity is significantly reduced ¨ the literature for Epoxyprene discloses
that the Latex
Allergen Activity is only 2-4% of that of untreated natural rubber latex
products. This is a
substantial improvement for those that may experience latex allergies. ENR is
used in
materials of the present disclosure to impart elongation, strength, and low
temperature
flexibility to the products disclosed and claimed.
ENR is traditionally cured with chemistries that are common in the rubber
compound
literature, e.g., sulfur cure systems, peroxide cure systems, and amine cure
systems.
According to the present disclosure, a specially prepared curative with
carboxylic acid
functionality is prepared to be used as the curative as fully disclosed in
Section 1 above.
There are a number of naturally-occurring polyfunctional carboxylic acid
containing
molecules, including but not limited to citric acid, tartartic acid, succinic
acid, malic acid,
maleic acid, and fumaric acid. None of these molecules are miscible in ENR and
thus have
limited effectivity and utility. It has also been found that a curative of,
for example, citric
acid, and an epoxidized vegetable oil may be prepared that is soluble in ENR.
Specifically,
curatives of epoxidized soybean oil (ESO) and citric acid have been prepared
with an excess
of citric acid to prevent gelation of the ESO. Citric acid itself is not
miscible in ESO, but it
has been advantageously been discovered that solvents such as isopropyl
alcohol, ethanol,
and acetone (for example but without limitation unless otherwise indicated in
the following
claims) may make a homogeneous solution of citric acid and ESO. In this
solution, the excess
citric acid is made to react with the ESO and create a carboxylic-acid-capped
oligomeric
material (that is still liquid) as shown in FIG. 1. The miscibilizing solvent
contains at least
some hydroxyl-containing (i.e., alcohol) solvent that at least partially
reacts with some of the
carboxylic acid functional groups on the citric acid. The majority of the
solvent is removed
with elevated temperature and/or vacuum ¨ leaving behind a curative that may
be used as a
miscible curative for the ENR. By thus constructing the curative, the
resultant material is
substantially free of petrochemical-sourced inputs.
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First Illustrative Embodiment and Process for the Creation of Curative that is
Used in the
Preparation of ENR-based Material
Curative was prepared by dissolving 50 parts of citric acid in a warm blend of
50 parts of
isopropyl alcohol and 30 parts of acetone. After the citric acid was
dissolved, 15 parts of
shellac flakes (blonde dewaxed) were added to the mixture along with 50 parts
of ESO. The
mixture was heated and stirred continually until all the volatile solvents had
evaporated. It is
noteworthy that the total residual volume is greater than that of the citric
acid, ESO, and
shellac ¨ meaning that some of the isopropyl alcohol (IPA) is grafted onto the
citric acid
capped curative (via an ester linkage). Varying the ratio of IPA to acetone
can vary the
degree of IPA grafting onto the curative.
Second Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 30 parts of the curative as prepared in the first embodiment. In
addition, 70 parts of
ground cork powder (MF1 from Amorim) was added as a filler. This mixture was
made on a
two-roll rubber mill according to normal compounding practices. The mixture
was sheeted
out and molded at 110 C for 30 minutes. It was found to be properly cured,
with similar
elongation and strain recovery as sulfur and peroxide cure systems.
Third Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 45 parts of the curative as prepared in the first embodiment. In
addition, 70 parts of
ground cork powder (MF1 from Amorim) was added as a filler. This mixture was
made on a
two-roll rubber mill according to normal compounding practices. The mixture
was sheeted
out and molded at 110 C for 30 minutes. It was found to be fully cured, but
with some
attributes of over-crosslinked systems; including lower tear resistance and
very high
resilience.
Fourth Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 15 parts of the curative as prepared in the first embodiment. In
addition, 70 parts of
ground cork powder (MF1 from Amorim) was added as a filler. This mixture was
made on a
two-roll rubber mill according to normal compounding practices. The mixture
was sheeted
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out and molded at 110 C for 30 minutes. It was found to be cured, but with a
relatively low
state-of-cure; with attributes such as low resilience and poor strain
recovery.
Fifth Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 30 parts of the curative as prepared in the first embodiment. In
addition, 70 parts of
ground cork powder (MF1 from Amorim) was added as a filler. Additionally, 20
parts of
garneted fiber (from recovered textiles) was added. This mixture was made on a
two-roll
rubber mill according to normal compounding practices. The mixture was sheeted
out and
molded at 110 C for 30 minutes. It was found to be fully cured and
additionally had a
relatively high extensional modulus in accordance with the fiber content.
Sixth Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 30 parts of the curative as prepared in embodiment 1. In addition,
60 parts of
ground cork powder (MF1 from Amorim) was added as a filler. Additionally, 80
parts of
garneted fiber (from recovered textiles) was added. This mixture was made on a
two-roll
rubber mill according to normal compounding practices. The mixture was sheeted
out and
molded at 110 C for 30 minutes. It was found to be fully cured and
additionally had a very
high extensional modulus in accordance with the fiber content.
Seventh Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 60 parts of the curative as prepared in embodiment 1. In addition,
35 parts of ESO
was added as a reactive plasticizer. In addition, 350 parts of ground cork
powder (MF1 from
Amorim) was added as a filler. Additionally, 30 parts of garneted fiber (from
recovered
textiles) was added. This mixture was made on a two-roll rubber mill according
to normal
compounding practices. The mixture was sheeted out and molded at 110 C for 30
minutes. It
was found to be fully cured, rigid, and additionally had a relatively high
extensional modulus
in accordance with the fiber content.
Eighth Illustrative Embodiment and Process for the Creation of Curative that
is Used in the
Preparation of ENR-based Material
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Curative was prepared by dissolving 50 parts of citric acid in a warm blend of
110 parts of
isopropyl alcohol. After the citric acid was dissolved, 50 parts of ESO was
added to the
mixture along with 10 parts of Beeswax. The mixture was heated and stirred
continually until
all the volatile solvents had evaporated. The total residual volume is greater
than that of the
citric acid, ESO, and beeswax ¨ meaning that some of the isopropyl alcohol
(IPA) is grafted
onto the citric acid capped curative (via an ester linkage). The reduced
liquid mixture was
added to fine precipitated silica (Ultrasil 7000 from Evonik) to make a 50 wt%
dry liquid
concentrate (DLC) for easy addition in subsequent processing.
Ninth Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 50 parts of the curative DLC as prepared in the eighth illustrative
embodiment
along with 30 additional parts of fine precipitated silica. It was found that
mixing of the
curative DLC prepared in eighth illustrative embodiment eliminated some
stickiness in
processing that was experienced when mixing in curative that was not pre-
dispersed as a
DLC. The resulting mixture was cured in a press at ¨50 psi at 110 C for 30
minutes to make
a translucent slab.
The material of this embodiment was found to have attributes that are
analogous to those
found in animal-hide leather; including slow recovery after folding, vibration
damping
attributes, and high tear strength. It is believed that the total silica
loading (55 parts) and this
particular curative contribute to the "lossy" characteristics of this
material. Without wishing
to be bound by theory, it is possible that the level of total silica loading
is approaching the
percolation threshold and creating particle-particle interactions that are
creating the lossy
attributes without limitation unless otherwise indicated in the following
claims. This is a
preferred mechanism to reliance on polymer formulations that experience a Tg
near room
temperature (e.g., ¨15 C-30 C) as a means to create a lossy material, as such
an approach
would lead to poor cold crack resistance.
Tenth Illustrative Embodiment and Process for ENR-based Material
Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100 parts
of
rubber to 30 parts of so-called "cottonized" hemp fiber, this mixture was
mixed on a two-roll
mill using a tight nip to get an even dispersion of fiber. To this masterbatch
50 parts of the
curative DLC as prepared in the eighth illustrative embodiment along with 30
additional parts
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of fine precipitated silica. The resulting mixture was cured in a press at ¨50
psi at 110 C for
30 minutes to make a translucent slab. The material of the tenth illustrative
embodiment was
found to have similar attributes as the material of the ninth illustrative
embodiment with the
change of having much lower elongation at break and much higher modulus in
accordance
with the fiber loading.
Eleventh Illustrative Embodiment and Process for ENR-based Material
A black batch of ENR-based material was prepared by mixing ENR-25 with coconut
charcoal
to achieve the desired black color. In addition to the black colorant, other
ingredients were
.. added to yield a processible batch of rubber. Other ingredients may include
clay, precipitated
silica, additional epoxidized soybean oil, castor oil, essential oil odorants,
tocopheryl
(Vitamin E ¨ as a natural antioxidant), and curative. This material was then
cured in a tensile-
plaque mold at 150 C for 25 minutes to complete the curing.
Twelfth Illustrative Embodiment and Process for ENR-based Material
A brown batch of ENR- based material was prepared by mixing ENR-25 with cork
powder to
achieve the desired brown color and texture. In addition to the cork, other
ingredients were
added to yield a processible batch of rubber. Other ingredients may include
clay, precipitated
silica, additional epoxidized soybean oil, essential oil odorants, tocopheryl
(Vitamin E ¨ as a
natural antioxidant), and pre-polymer curative. This material was then cured
in a tensile-
plaque mold at 150 C for 25 minutes to complete the curing.
Tensile stress-strain curves are shown in FIG. 9 for materials prepared
according to the
eleventh and twelfth embodiments. It can be seen that the cork-filled brown
batch (twelfth
embodiment) is higher in modulus than the black batch (eleventh embodiment)
for this
particular example. In these two illustrative embodiments, the brown batch
(twelfth
embodiment) had a Shore A hardness of 86 while the black batch (eleventh
embodiment) had
a Shore A hardness of 79.
The optimal amount of the additional materials may vary according to the
specific application
of the ENR-based material, and various ranges for same are shown in Table 2.
Ingredient Preferred Range (Percent Acceptable Range (Percent
of Total Product Weight) of Total Product Weight)
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ENR-25 40-60 20-90
Curative 2-10 1-50
Cork 3-10 0-70
Colorant 0-15 0-50
Precipitated Silica 15-35 0-50
EVO 0-10 0-30
Non-reactive vegetable oil 0-10 0-30
Odorant 0.5-3 0-10
Vitamin E/antioxidant 0.2-2 0-4
Mineral filler (e.g., clay) 0-15 0-50
Table 2¨Acceptable and Preferred Ranges of Other Ingredients.
Variations in the other ingredients: clay, precipitated silica, additional
epoxidized soybean
oil, castor oil, and/or amount of curative may be used to vary the modulus of
a batch/recipe
within a range that is characteristic of traditional rubber recipes. By those
well versed in
rubber compounding it is recognized that formulations of rubber may be
selectively
compounded with hardnesses ranging from approximately 50 Shore A up to about
90 Shore
A. The illustrative formulations show that these compounds fall within the
range of expected
performance for epoxidized natural rubber. Furthermore, it is known that
traditionally
compounded natural rubber may achieve strength values from 10-25 MPa. The
eleventh
illustrative embodiment displays physical properties in line with
traditionally compounded
natural rubber.
Materials made according to this disclosure may further be reinforced with
continuous fiber
to make stronger products. Methods for reinforcement may include but are not
limited to use
of both woven textiles, non-woven textiles, unidirectional strands, and plied
unidirectional
layers unless otherwise indicated in the following claims. Reinforcement may
preferably
come from natural fibers and yams. Illustrative yarns may include, but are not
limited to,
cotton, jute, hemp, ramie, sisal, coconut fiber, kapok fiber, silk, or wool
and combinations
thereof unless otherwise indicated in the following claims. Regenerated
cellulose fibers such
as viscose rayon, Modal (a specific type of viscose, by Lenzing), Lyocell
(also known as
Tence10, by Lenzing), or Cuprammonium Rayon may also be used without
limitation or
restriction, as suitable for a particular application, unless otherwise
indicated in the following
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claims. Alternatively, reinforcement may require the strength of synthetic
fiber yarns based
on para-aramids, meta-aramids, polybenzimidazole, polybenzoxazole, and similar
high
strength fibers. In another illustrative embodiment, a reinforcement layer
and/or material may
be configured from a protein-based fiber, which fibers include but are not
limited to of wool,
silk, alpaca fiber, qiviut, vicuna fiber, llama wool, cashmere, and angora
unless otherwise
indicated in the following claims. Illustrative natural yarns may beneficially
be treated by the
natural fiber welding process to improve their strength, reduce their cross-
sectional diameter,
and improve fiber-to-elastomer bonding characteristics. Such yarns may be
plied into threads
that provide interpenetration features between reinforcement and elastomer as
well as
improve the strength of the reinforcement. For certain applications it may be
preferred to
provide reinforcement by unidirectional reinforcement in plied layers as
compared to woven
and knit reinforcement. It has been found that such woven and knit
reinforcement may
improve product stiffness but may negatively impact tear strength by creating
stress-
concentration features around yarns and fibers. In contrast, unidirectional
reinforcement at
various ply angles may avoid such stress concentrating features. In a related
way, non-woven
mats may be used as reinforcement as they do not contain regularly oriented
stress-
concentrating features but do enable long reinforcement fiber lengths at high
fiber volume
fractions. In a related way, integrally mixed fiber content has been found to
improve stiffness
but decrease tear strength at certain volume and weight fractions. Tear
strength improvement
is observed when total fiber content exceeds 50 phr (in traditional rubber
compounding
nomenclature), especially with even dispersion and good retention of fiber
length during
processing.
Molding and curing of materials according to the present disclosure has been
found to require
only modest pressure to achieve porosity-free articles. While traditional
rubber cure systems
evolve gasses and thus require molding pressures generally greater than 500
psi and often
closer to 2000 psi, the compounds disclosed herein only require molding
pressure of 20 psi ¨
100 psi, or more specifically 40 psi ¨ 80 psi to achieve consolidation and
porosity-free
articles. The actual required pressure may be dependent more on the amount of
material flow
and detail required in the final article. Such low molding pressures allow the
usage of much
lower tonnage presses that are correspondingly less expensive. Such pressures
also allow
much less expensive tooling; even embossed texture papers have been found to
create
suitable patterns in elastomeric materials made according to this disclosure
and such texture
papers are found to be reusable for multiple cycles without loss of pattern
detail. The material
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edge strength has been found to be adequate even when using open-sided tooling
¨ this
allows for faster tool cleaning and significantly reduced tooling costs.
The low molding pressures further allow for such elastomeric materials to be
molded directly
onto the surface of resilient and porous core substrates. For example, the
material may be
overmolded onto non-woven insulative mats as a resilient flooring product or
automotive
interior product that exhibits soft-touch and sound absorption
characteristics. Similarly, the
product may be overmolded onto softwoods or similar low compressive strength
substrates
without damage to the substrate.
As previously described, certain catalysts are known in the art to speed up
the carboxylic acid
addition to epoxide groups and such may be used in formulating recipes
according to the
present disclosure without limitation unless otherwise indicated in the
following claims.
Animal-hide leather has distinctive characteristics in terms of elongation,
resiliency, loss
modulus, and stiffness that are different than a regularly compounded
elastomer. In
particular, animal-hide leather may be folded back on itself without cracking
¨ largely
independent of temperature. That is, it does not have a material phase that
becomes brittle at
low temperatures. Animal-hide leather also has vibration damping
characteristics that are less
common with regularly compounded elastomeric compounds. Animal-hide leather
has slow
recovery after creasing or folding, but does generally recover completely with
minimal
plastic deformation. These attributes may be mimicked in materials compounded
according to
the present disclosure in the illustrative embodiments and methods for same
disclosed herein.
C. Additional Treatments
Articles produced according to this disclosure may be finished by any means
known in the
art. Such means include but are not limited to embossing, branding, sanding,
abrading,
polishing, calendering, varnishing, waxing, dyeing, pigmenting, and the like
unless otherwise
indicated in the following claims. Such articles may be configured to exhibit
characteristics
very analogous to animal-hide leather. The surfaces then may be treated with
natural oil or
wax protectants, subject to a particular application.
D. Applications/Additional Illustrative Products
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Articles molded with materials according to this disclosure may be used as
plant-based
alternatives to petrochemical-based leather-like products and/or animal-hide
leather products.
In one illustrative embodiment the articles may be molded substantially as
sheets with
various textures according to the desired application. The sheets may be used
in durable
goods such as upholstery, seating, belts, shoes, handbags, purses, backpacks,
straps,
equestrian gear, wallets, cellular phone cases, and similar articles without
limitation unless
otherwise indicated in the following claims. Alternatively, such materials may
be molded
directly to the shape of the final article in applications such as shoe soles,
shoe toes, shoe heal
cups, shoe uppers, purses, horse saddles and saddle components, helmet
coverings, chair
armrests, and similar articles.
Materials according to this disclosure may be overmolded onto resilient
materials and thus be
used as flooring, exercise mats, or sound absorption panels. Similarly, those
materials could
be overmolded onto garments as, for example, a knee patch or elbow patch for
improved
abrasion resistance for a region of a garment. Likewise, motorcycle garments
(e.g., chaps)
and equestrian gear may be overmolded of materials according to this
disclosure to provide
improved local abrasion resistance and protection.
Materials according to this disclosure may be molded into complex three-
dimensional articles
and multi-laminated articles. That is, certain formulations according to this
disclosure may
provide improved tear strength, while other formulations according to this
disclosure may
provide improved abrasion resistance. Such formulations may be laminated and
co-molded to
provide articles with improved overall performance compared with an article
made of only
one formulation. Three-dimensional articles may be molded to provide
additional product
features, attachment points, and other functionality without limitation unless
otherwise
indicated in the following claims. Three-dimensional articles may also consist
of multiple
formulations arranged at various locations within an article to provide
functionality required
for each location.
One example of such molded-in functionality is shown in FIGS. 10A & 10B, which
provides
a perspective view of a portion of a belt made of an ENR-based material.
Specifically, in
FIG. 10A, a tapered feature (shown on the right-hand side of FIG. 10A) may be
molded into a
sheet that is later slit into belt sections. The reduced thickness (which may
be due to the
absence of a backing material/backing layer (e.g., non-woven mat) in the area
having reduced
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thickness) allows for a folded buckle retention area that is substantially
similar in thickness to
belt sections that are not folded over on itself, which is shown in FIG. 10B
where the
reduced-thickness area has been engaged with a buckle. Additionally, the
region that is
folded back onto itself may be preferentially bonded in place with additional
resin or ENR-
based material molded between the folded region with a cure cycle that is
similar to that used
during the initial molding of the sheet.
Shown in FIG. 11 are a series of retention grooves and ridges that may be
molded into the
end of the belt to provide a friction-based retention feature. That is, some
belts made with
woven nylon or other textiles are tightened and retained on the wearer by
friction between
ribs woven into the belt and a metal bar used in the clasp. Such features may
be advantageous
in that they prevent stress risers from developing around punched holes used
for retention in
common belt buckles. Retention grooves & ridges and/or other features for
retaining the
position of a portion of a belt easily molded into a belt sheet by the
creation of matching
features in the mold tooling (which may be silicone or metal) when making an
ENR-based
material according to the present disclosure.
ENR-based materials configured for use as a belt may be made in sheets and may
be
produced by molding according to the pattern illustrated in FIG. 12. As shown
in FIG. 12, the
sheet may be comprised of various layers, wherein each outside layer of the
sheet may be
comprised of an ENR-based material (e.g., "sheeted rubber preform" in FIG. 12)
with one or
more fibrous backing materials/backing layers positioned therebetween. The
backing
materials may be comprised of a woven reinforcement or a non-woven mat in the
illustrative
embodiment shown in FIG. 12, but any suitable backing material/backing layer
may be used
without limitation unless otherwise indicated in the following claims. At
least one of the
backing materials may be a coated fabric (as shown in FIG. 12 for the layer
labeled "non-
woven mat"), which may be constructed in accordance with Section 2 described
herein
above. Texture paper may be positioned adjacent one or both ENR-based material
layers to
provide the desired aesthetics to the outer layers of the sheet and resulting
article. Finally, a
silicone release sheet may be positioned adjacent one or both texture papers
for ease of use.
It has been found that the relatively low required pressure to yield a
properly cured specimen
utilizing ENR-based materials allows for the use of low-cost paper and
silicone tooling. So-
called texture papers are used in polyurethane and vinyl leather alternatives
to achieve the
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desired texture. It has been found that these texture papers likewise are
effective in creating
patterns in ENR-based materials as disclosed herein. An advantageous molding
configuration
is shown in FIG. 12, wherein release silicone sheets are provided as the top-
most and bottom-
most layers in the sandwich that is molded under temperature and pressure. If
the "outside"
faces of the belt are desired to be textured, texture paper may be provided
next to the silicone
sheets. These may advantageously be treated with a release aid to promote easy
release and
reuse of the texture paper. Silicone and vegetable oil have both been found to
be effective in
release and reuse of the texture paper but any suitable release agent may be
used without
limitation unless otherwise indicated in the following claims.
The uncured rubber pre-form sheets may be loaded into the sandwich next to the
texture
paper(s). Between the rubber pre-form sheets a non-woven mat and/or woven
reinforcement
layer(s) may be provided. In one illustrative embodiment, the non-woven mat
may comprise
recycled textiles, hemp fibers, coconut coir fibers, or other environmentally
benign
(biodegradable) fibers, and/or combinations thereof without limitation unless
otherwise
indicated in the following claims. In one illustrative embodiment the woven
reinforcement
layer may comprise jute burlap or similar open-structure woven product that is
high in
strength and biodegradable. In another illustrative embodiment so-called
cotton monk's cloth
may be also used as a woven reinforcement layer without restriction unless
otherwise
indicated in the following claims. In some configurations open-structure woven
products
provide relatively good tear strength when compared to tight woven fabrics. In
another
illustrative embodiment, a reinforcement layer (woven or non-woven) may be
configured
from a protein-based fiber, which fibers include but are not limited to of
wool, silk, alpaca
fiber, qiviut, vicuna fiber, llama wool, cashmere, and angora unless otherwise
indicated in the
following claims.
ENR-based materials configured for use as leather substitutes may be used in
applications
where animal-hide leather is used today. Such applications may include belts,
purses,
backpacks, shoes, table tops, seating, and the like without limitation unless
otherwise
indicated in the following claims. Many of these articles are consumable items
that if made
from petrochemical-based leather-like products are non-biodegradable and are
non-
recyclable. If such items are made from the material disclosed herein, they
would be
biodegradable and thus not create a disposal problem. Furthermore, unlike
animal-hide
leather, which requires significant processing to be made durable and stable
(some of which
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uses toxic chemicals), the materials disclosed herein may require less
processing and will use
environmentally friendly chemicals. Additionally, animal-hide leather is
limited in size and
may contain defects that render large pieces inefficient to produce. The
material disclosed in
at least one embodiment herein does not have the same kind of size limitations
as the reaction
between epoxide groups and carboxylic groups does not create any condensation
by-products,
there is no inherent limit to the cross-sectional thickness that may be
created.
In another application for material produced according to the present
disclosure, the leather
substitute material (which may be configured as an ENR-based material) may be
used for
footwear, specifically the upper portion of the footwear. Generally, it is
contemplated that
leather substitute material may be engaged with a fabric backing. In one
illustrative
embodiment the fabric backing may be comprised of Rayon (e.g., Tencel,
Lyocell, etc.), and
in another illustrative embodiment the fabric backing may be comprised of
canvas, hemp, or
other suitable material. It is contemplated that the optimal fabric backing
may vary depending
on the specific application and is therefore in no way limiting to the scope
of the present
disclosure unless otherwise indicated in the following claims. It is further
contemplated that
for at least some applications, the leather substitute material and fabric
backing may have the
following characteristics:
= Tensile Strength (ASTM D 5035-2011) 600 N/5cm,
= Elongation (ASTM D 5035-2011) 80% +/-20
= Color fastness to rubbing (crocking) (ISO 20433:2012), My >4 and Wet >4
* Bonding Strength of coated material I between leather substitute material
(which may be
configured as an ENR-based material) layer and the fabric backing material,
2.5 N/mm
to Bally Flex at room temperature (e.g., ¨15 C-30 C). ASTM D 6782-13 (23 1),
100,000
cycles, Pass
to Abrasion ¨ Taber (ASTM D 3884-09, 11-22, 1.000g,> 1000 cycles), Pass
to Color fastness to wash (1SO-105-006:2010), >4
However, such characteristics are not meant to be limiting in anyway and are
for illustrative
purposes only unless otherwise indicated in the following claims.
Generally, it has been observed through testing that when silica is added as a
type of filler
with the leather substitute material (which may be configured as an ENR-based
material), the
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result may be a higher cohesive strength within the leather substitute
material layer than is
shown in a leather substitute material layer without a silica filler. It has
also been observed
that a silica filler may aide with fatigues life/bally flex, which may be
evident specifically
when rice hulls are also used as a filler. Additionally, because silica does
not hide certain
characteristics of other materials (e.g., silica provides a certain degree of
translucency in
certain applications as a filler material), when used with rice hulls, the
speckles, texture,
and/or other characteristics of the rice hulls (or other filler materials in
other illustrative
embodiments) may be more pronounced than when filler materials other than
silica are used.
It is contemplated that rice hull ash may be used in place of silica as a
filler in certain
applications to achieve desirable characteristics of the resulting material.
It has further been found that using Tencel as a backing fabric results in the
composite
material (i.e., leather substitute adhered to a fabric backing) exhibits a
higher tensile
elongation compared to using cotton as a backing fabric. However, the specific
configuration
of the backing fabric and/or leather substitute material, method of adhering
the various layers,
dimensions, etc. may also affect the characteristics of same without
limitation unless
otherwise indicated in the following claims.
4. Mechano-chemically Modified Thermoset Material
A. Background
Leather-like materials based on synthetic polymers such as polyurethane (PU)
and polyvinyl
chloride (PVC) are well known in the art. These materials have been formulated
to have
haptics that mimic, in many ways, the feel of animal leather. Animal leather
is a collagen-
based structure that is usually filled with waxes and oils that impart both
softness and a slick
surface - termed "buttery" by those in the art. PVC, for example, may achieve
similar haptics
by the combination of the polymer itself that may have a glass transition
temperature, Tg,
above room temperature (e.g., greater than ¨23 C) combined with plasticizers
that drop the
bulk material stiffness so that it remains flexible well below room
temperature (e.g., less than
¨23 C). PU, in another example, may achieve similar haptics by the combination
of so-called
.. hard block domains (with a Tg above room temperature) and soft block
domains (with a Tg
below room temperature) synthesized into the polymer backbone. In these
examples, there is
a phase or constituent with a Tg above room temperature (collagen, PVC
polymer, and PU
hard blocks) and a phase or constituent with a Tg below room temperature
(tanning agents
and oils for animal leather, plasticizers for PVC, and soft block domains for
PU). This
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combination of phases or constituents that have a Tg above room temperature
and phases or
constituents with a Tg below room temperature and may yield a favorable haptic
combining
softness of the bulk article without imparting a "grippy" surface.
Materials based on natural rubber or other related polymers, such as
epoxidized natural
rubber, tend to have a polymer phase with a single Tg that is below room
temperature; thus
compounds based on natural rubber (NR) or epoxidized natural rubber (ENR) tend
to have a
"grippy" surface that is undesirable when developing a leather-alternative
material. It would
be desirable to combine the beneficial low temperature flexibility and
softness that comes
from NR or ENR with a slick or buttery surface haptic for the creation of a
leather-alternative
material.
B. Summary
Disclosed is a combination of a plant-based all-natural polymer that can be
combined with
ENR to yield a polymeric mixture that maintains the excellent low temperature
flexibility of
the ENR while delivering the haptics associated with a polymer having a Tg
nearer room
temperature (e.g., ¨15 C-30 C).
In another embodiment, disclosed is a combination of a plant-based all-natural
polymer that
can be combined with ENR and another optional plasticizer that further
suppresses the glass
transition temperature to impart excellent low temperature flexibility (down
to -10 C or
lower).
Disclosed is an illustrative method of selectively reversing covalent chemical
crosslinks
(which reversing may also referred to herein as "de-crosslinking") in a
thermoset material
through mechano-chemical processing using low temperature (e.g., less than 70
C) and high
shear, which may be performed by passing a thermoset material repeatedly
through a narrow
gap (<1 mm) of a two-roll rubber mill (approximately 1.25:1 friction ratio) or
through mixing
in an internal mixer. The method has been found to cause scission primarily to
crosslinks to
partially reverse the cure. Such mechano-chemically modified thermoset may be
used as one
constituent in a mixture with ENR to yield a leather-like alternative material
with improved
haptics .
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As used herein, the term "thermoset material" is meant to include all
thermosets without
limitation unless otherwise indicated in the following claims, including those
thermosets that
are made via resin (liquid) precursors, gum precursors, semi-solid precursors,
thermoplastic
precursors, and/or combinations thereof
Various methods exist for determining the power-per-unit-volume of thermoset
material
required to selectively break the crosslinks in the thermoset material
disclosed herein, and the
scope of the present disclosure is in way limited by a specific method for
determining same
unless otherwise indicated in the following claims. In one illustrative method
for determining
the aforementioned power-per-unit-volume of thermoset material, the thermoset
material may
be mixed on a two-roll mill with a nip gap of 0.5 mm. The power consumption
may be
approximately 5000W (5 kW). As the thermoset material fills the nip width of
30 cm, it may
be assumed that the majority of power input into the thermoset material
happens below a nip
gap of 1.5 mm because experiments show very little mechano-chemical de-
crosslinking at
this nip gap or larger. For mills configured with rolls with a radius of 75 mm
(6-inch rolls),
this corresponds to an arc of approximately 13 (+/- 6.5 around the point of
closest
approach). One may accordingly estimate that the volume of material within
this nip gap
across the width of the mill is approximately 7.5 ml. Therefore, a reasonable
estimate of the
instantaneous power input to enable mechano-chemical de-crosslinking is
5000W/0.0075
liters = 6.67 x 105 W/1.
However, in some instances, the power consumption on the two-roll mill may be
as low as
2000W (2kW). The mill geometry and nip gap remain the same and the mill width
remains
the same. In these instances, the instantaneous power input to enable mechano-
chemical de-
crosslinking may be 2000W/0.0075 liters = 2.67 x 105 W/1.
Through experimentation, the lowest shear variation that has been observed to
selectively de-
crosslink the thermoset material through a mechano-chemical process mechano-
chemical de-
crosslinking may occur with a minimum nip gap of 0.8 mm with an estimated
power
consumption of 2000W (2kW). In this instance, the estimated volume of
thermoset material
experiencing the high shear near the nip may be as much as approximately 10
ml. In this
example, the instantaneous power input to enable mechano-chemical de-
crosslinking may be
2000W/0.01 liters = 2 x 105 W/1.
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In the preceding illustrative embodiments, the mechano-chemical de-
crosslinking may be
characterized by very high instantaneous power-per-volume shear mixing
followed by
periods of cooling so that the temperature of the thermoset material that is
being mixed never
exceeds approximately 70 C (above which temperature the thermoset material may
begin re-
curing, that is, re-crosslinking). On a two-roll mill, the high-shear mixing
zone has been
estimated to be happening over an arc length of approximately 130, thus by
deduction the
estimated low-shear or no-shear cooling time occurs during the remaining
periphery of the
roll (i.e., the remaining approximately 347 of travel). Accordingly, the high
shear time may
be experienced by the thermoset material for approximately 13/360, or 3.6% of
the total
mixing time. In this way, the maximum material temperature may be limited,
despite having
instantaneous times of very high-power input (per volume).
Disclosed is a reaction product between an epoxidized plant-sourced
triglyceride (an example
of which may be epoxidized soybean oil (ESO)) and a naturally occurring
polyfunctional
carboxylic acid (an example of which may be citric acid) wherein the thermoset
reaction
product contains B-hydroxyesters as the linkages between the epoxidized plant-
sourced
triglyceride and the naturally occurring polyfunctional carboxylic acid. It
has been
unexpectedly discovered that the B-hydroxyester linkages may be selectively
and reversibly
broken by mechanical shear only. That is, the thermoset matrix sourced from
small and
highly branched precursor molecules may be transformed into a millable gum by
the action of
high-shear mixing. Such mechanically masticized thermoset has been found to be
capable of
being re-cured into a thermoset by the re-application of heat without the
addition of
additional curative functionality (that is, without the addition of virgin
epoxidized plant-
sourced triglyceride or carboxylic-acid functionality).
Disclosed is an epoxidized natural rubber that is crosslinked by a carboxylic-
acid containing
curative. Crosslinks between the epoxide groups and the carboxylic-acid
curative form B-
hydroxyesters. Such B-hydroxyesters are known to be capable of thermally-
induced
transesterification reactions. Such reactions have been used to make so-called
"self-healing"
and recyclable thermosets.' In the prior art, it has been assumed that
transesterification
reactions proceed in a sort of zero-sum rearrangement where the total number
of linkages is
1,'Self-healable polymer networks based on the cross-linking of epoxidized
soybean oil by an aqueous citric
acid solution", Facundo I. Altuna, Valeria Pettarin, Roberto J. J. Williams,
Green Chem., 2013, 15, 3360
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generally stable, Leibler et. al states, "The underlying concept is to allow
for reversible
exchange reactions by transesterification that rearrange the network topology
while keeping
constant the total number of links and the average functionality of cross-
links."2
It has been unexpectedly discovered that by pairing a high molecular weight
polymer based
on a carbon-carbon backbone with crosslinks of B-hydroxyesters, the crosslinks
may be
selectively and reversibly broken by mechanical shear only. That is, a high
molecular weight
elastomer such as epoxidized natural rubber that has been crosslinked
(vulcanized) through B-
hydroxyesters may be mechanically processed by very high shear such that the
high
molecular weight linear rubber may be substantially retained while the
crosslinks are
selectively broken in such a way that their initial functionality is
regenerated. The resultant
re-milled rubber may be re-molded without the addition of additional curative
¨
demonstrating that the curative is not only selectively broken, but also that
the carboxylic-
acid functionality and epoxide functionality are regenerated during the
breaking of the
crosslinks. Such mechanically induced regeneration of curative functionality
has not before
been disclosed.
Disclosed is the combination of virgin epoxidized natural rubber and
mechanically
masticized thermoset material (which may be configured as a thermoset resin)
that was
formed as the reaction product between an epoxidized plant-sourced
triglyceride and a
naturally occurring polyfunctional carboxylic acid. Such reaction product may
be preferably
produced according to the methods disclosed Section 2 - Coated Fabrics, though
the scope
thereof is not so limited unless otherwise indicated in the following claims.
The mechanically
masticized thermoset material may function as the curative for the virgin
epoxidized natural
rubber. Such mechanical masticization of the thermoset material and mixing of
the recipe has
been found to be able to occur concurrently.
C. Detailed Description
Thermoset materials (and specifically, thermoset resins) and thermoset
elastomers are well
known in the art. In most cases, the covalent bonds formed between molecules
have strength
characteristics that are commensurate with the strength characteristics within
the precursor
Silica-Like Malleable Materials from Permanent Organic Networks", D.
Montarnal, M. Capelot, F.
Tonmilhac and L. Leibler, Science, 2011, 334, 965-968.
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molecules. In such materials, mechanical shear results in turning the
thermoset material into a
granule or powder that may be used as a filler in new materials, but is not
capable of
returning the thermoset material into a high molecular weight gum, having
characteristics
substantially the same or even similar to the starting precursor material(s).
Some ionically
crosslinked materials, when formed by the coordination of charges along the
polymer
backbone, may be made to flow under either high shear or the application of
very high
temperatures, but this type of reversible thermoset behavior is not known
among covalently
bonded thermoset materials.
It is known in the art that crosslinks between the epoxide groups and a
carboxylic-acid
curative form B-hydroxyesters. Such B-hydroxyesters are known to be capable of
thermally
induced transesterification reactions. Such reactions have been used to make
so-called "self-
healing" and recyclable thermosets. In the prior art, it has been assumed that
transesterification reactions proceed in a sort of zero-sum rearrangement
where the total
number of linkages is generally stable, Leibler et. al states "The underlying
concept is to
allow for reversible exchange reactions by transesterification that rearrange
the network
topology while keeping constant the total number of links and the average
functionality of
cross-links."
It has been unexpectedly discovered that B-hydroxyester crosslinks may be
selectively and
reversibly broken (i.e., de-crosslinked) by mechanical shear only. That is, a
thermoset
material with linkages that are B-hydroxyesters, as shown in the cured
thermoset resin of FIG.
13 (wherein small arrows on the right side of the figure show reactive sites
in for the
compound), may be mechanically processed by very high shear such that the
thermoset
material may be masticized as the crosslinks are selectively broken in such a
way that their
initial functionality is regenerated. The resultant masticized thermoset may
be re-cured
without additional curative ¨ demonstrating that the curative is not only
selectively broken,
but also that the carboxylic-acid functionality and epoxide functionality are
regenerated
during the breaking of the crosslinks as shown in FIG. 15. Such mechanically
induced
regeneration of curative functionality has not before been disclosed.
i. Regenerated Thermoset Materials Based on Epoxidized Natural Rubber
It has been unexpectedly discovered that by pairing a high molecular weight
polymer based
on a carbon-carbon backbone (such as epoxidized natural rubber) with
crosslinks of B-
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hydroxyesters, the crosslinks are selectively and reversibly broken by
mechanical shear only.
That is, a high molecular weight elastomer such as epoxidized natural rubber
that has been
crosslinked (vulcanized) through B-hydroxyesters may be mechanically processed
by very
high shear such that the high molecular weight linear rubber may be
substantially retained
while the crosslinks are selectively broken in such a way that their initial
functionality is
regenerated. The resultant re-milled rubber, which has been de-crosslinked
(also called
devulcanized), may be re-molded without additional curative ¨ demonstrating
that the
curative is not only selectively broken, but also that the carboxylic-acid
functionality and
epoxide functionality are regenerated during the breaking of the crosslinks.
Such
mechanically induced regeneration of curative functionality has not before
been disclosed.
A rubber compound of epoxidized natural rubber (ENR-25) and a carboxylic-acid
functional
curative as disclosed in Section 1 above may be mixed with additional fillers
and additives as
may be common in the art. In one illustrative embodiment, the compound
contains powdered
cork and precipitated silica. A series of rheometer traces is shown in FIG. 16
from a moving
die rheometer (MDR) as measured at 150 C for 30 minutes. The initial trace
shows a
characteristic cure curve with a brief induction time and then marching
modulus for the 30-
minute cure. The rheometer sample was then subject to remilling on a lab-scale
(6" diameter
X 12" wide) two-roll rubber mill. After a few passes through the mill wherein
the sample
exhibited nervy behavior, it gradually became flowable in a similar way to
uncured rubber
under continued mixing. The second rheometer curve ("second trace" on FIG. 16)
on this
particular sample shows a higher initial modulus but thereafter cures to
roughly the same
final stiffness at a similar rate. This particular sample of material was
subsequently remilled
again and cured again. This was repeated eleven times ¨ the sixth and eleventh
cure traces are
shown in FIG. 16. It can be seen that the general shape of the cure curve is
similar for all re-
curing experiments; the modulus drops as the number of recycling loops
increases, but each
time, the sample was shown to be capable of re-curing without the addition of
more curative.
The twelfth cure curve ("twelefth trace, added curative" on FIG. 16) reflects
the addition of a
small amount of curative that was able to increase the modulus of the sample.
The series of cure curves of FIG. 16 shows that the compound may be de-
crosslinked by the
application of mechanical shear only ¨ without the addition of heat (that is,
the rolls of the
two-roll mill were not heated for any of these experiments). Furthermore, the
rheometer
traces show that the curative is capable of re-crosslinking the epoxidized
natural rubber after
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mechanical de-crosslinking. In contrast to prior literature on
transesterification, it has been
shown that the total number of crosslinks do not need to be maintained to
regenerate solid
materials with mechanical integrity. The curative may regenerate itself after
being sheared
apart by mechanical forces.
In another set of experiments, the same recipe that was used in FIG. 16 was
subject to
rheometry at a series of increasing temperatures. This data is shown in FIG.
17 for the
temperatures of 150 C, 175 C, 200 C, and 225 C. It can be seen that the state
of cure
increases with increasing temperature to 200 C. There is some small evidence
of reversion at
200 C. At 225 C, we see an initial cure that is followed by rapid reversion
that is nearly
complete at the end of the 30-minute test. This is evidence that the
crosslinking bonds are
substantially weaker than the epoxidized natural rubber itself, which has an
onset of thermo-
oxidation at approximate1y250 C. Therefore, we may surmise that mechanical
stresses are
capable of breaking the weaker subset of covalent bonds ¨ in this case, the B-
hydroxyester
crosslinks.
ii. Regenerated Thermoset Materials based on Epoxidized Plant Oil and
Naturally
Occurring Polyfunctional Acid
It has been unexpectedly discovered that the reaction product of two small
molecules (such as
epoxidized soybean oil (ESO) and citric acid), wherein the covalent linkages
between the
molecules of the thermoset material (which for this illustrative embodiment is
configured as a
thermoset resin) are B-hydroxyesters, may be transformed into a millable gum
by mechanical
shear only. That is, a highly branched elastomer may be transformed into a
more linear and
extensible material through the reversible fracture of a subset of the B-
hydroxyester covalent
linkages as shown in FIG 15. This millable gum may furthermore be used
advantageously in
two or more ways. In one preferred illustrative embodiment, the millable gum
may be
subsequently combined with any number of fillers, plasticizers, or functional
additives and
then re-cured - without the addition of additional epoxidized plant-sourced
triglyceride (such
as ESO) or naturally occurring polyfunctional carboxylic acid (such as citric
acid). In another
preferred illustrative embodiment, the millable gum may be sheeted out without
combination
with additional fillers, plasticizers, or functional additives and then re-
cured as a transparent
film (either by itself or in contact with backing fabric or other backing
material). In another
preferred illustrative embodiment, the millable gum may be subsequently
combined with
virgin epoxidized natural rubber wherein the epoxidized natural rubber is
crosslinked through
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the action of the regenerated carboxylic acid functionality that was achieved
through the
mechanical shear of the thermoset material.
By way of illustration, and without limitation unless so indicated in the
following claims,
various processes and parameters thereof are described in detail below. The
values for the
parameters given below are for illustrative purposes only and are in no way
limiting unless
otherwise indicated in the following claims. Other parameter values, methods,
equipment,
etc. may be used without limitation unless otherwise indicated in the
following claims.
Example 1
100 parts of Citric Acid, 100 parts of ESO, and 400 parts of Isopropyl Alcohol
(IPA) are
charged into a vacuum-capable reactor vessel. The mixture is slowly heated
over the course
of 8 hours with constant stirring and under modest vacuum (>50 Ton). The IPA
is condensed
during the reaction period and removed from the solution. At the end of the
reaction period,
when substantially all of the unbound and unreacted IPA is removed, the
temperature of the
reactor vessel rises quickly and the reaction is halted when the reaction
product reaches
110 C.
Example 2
.. 109 parts of the reaction product of Example 1 is mixed with 100 parts of
ESO to yield a
curable resin. This resin may be cured overnight at 80 C or within two hours
at 125 C to
make an elastomeric solid.
Example 3
The cured elastomeric solid of Example 2 is passed repeatedly through a tight
nip on a rubber
mill. The friction ratio is 1.25:1 and the nip is set to less than 0.5 mm.
After a few passes, the
powdery material begins to masticate and within about 3-7 minutes of mixing a
millable gum
is generated. This millable gum may be sheeted out and re-cured as a
transparent sheet or it
may be combined with fillers, plasticizers, and/or functional additives to
yield a compound
that may be cured under heat (e.g. 150 C for 5 minutes) to make a thermoset
elastomer. The
millable gum may be combined with epoxidized natural rubber (ENR) and ENR-
based
compounds and act as a curative for the ENR.
Example 4
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109 parts of the reaction product of Example 1 is mixed with 100 parts of ESO
along with 7
parts of propylene glycol and 3.5 parts of olive-derived emulsifying wax to
yield a curable
resin. This resin may be cured overnight at 80 C or within two hours at 125 C
to make an
elastomeric solid.
Example 5
The cured elastomeric solid of Example 4 is passed repeatedly through a tight
nip on a rubber
mill. The friction ratio is 1.25:1 and the nip is set to less than lmm. After
a few passes, the
powdery material begins to masticate and within about 3-7 minutes of mixing a
millable gum
is generated. This millable gum may be sheeted out and re-cured as a
transparent sheet or it
may be combined with fillers, plasticizers, and/or functional additives to
yield a compound
that may be cured under heat (e.g. 150 C for 5 minutes) to make a thermoset
elastomer. The
material of example 5 is more easily masticated than the material of example
3. The millable
gum may be combined with epoxidized natural rubber (ENR) and ENR-based
compounds
and act as a curative for the ENR.
iii. Thermoset Material Blends Based on Virgin ENR and Regenerated Thermoset
Materials
based on Epoxidized Plant Oil and Naturally Occuring Polyfunctional Acid
By combining the technology of mechano-chemically regenerated thermoset
materials (where
such materials have been found to regenerate the original chemical
functionality of epoxide
groups and carboxylic acid groups) with virgin ENR, the regenerated
functionality is able to
cure (i.e., crosslink) the epoxide groups in the ENR without the addition of
additional
curative. This is laid out in the following examples.
Example 6
40 parts of ENR-50 is mixed with 63 parts of the cured resin of Example 4 in
the previous
section. It has been found that there is sufficient shear during the mixing of
the ENR-50 with
the cured resin of Example 4 that the cured resin is mechano-chemically broken
down (de-
crosslinked) and thus becomes a source of carboxylic acid functionality that
is capable of
curing the ENR-50. This mixture of elastomeric gum materials may be further
combined with
fillers, plasticizers, and functional additives to yield a compound that may
then be cured as an
elastomeric solid. In one illustrative embodiment, the fillers may include
cork powder,
ground rice hulls, activated carbon, activated charcoal, kaolin clay,
metakaolin clay,
precipitated silica, talc, mica, corn starch, mineral pigments, and/or various
combinations
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thereof without limitation unless otherwise indicated in the following claims;
the plasticizers
may include both reactive plasticizers such as epoxidized soybean oil, semi-
reactive
plasticizers such as glycerol, propylene glycol, and castor oil, and non-
reactive plasticizers
such as naturally occurring triglyceride plant-based oils and/or various
combinations thereof
without limitation unless otherwise indicated in the following claims; the
functional additives
may include antioxidants (such as tocopherol acetate (Vitamin E)), UV
absorbers (such as
sub-micron TiO2), antiozonants, cure retarders (such as alkali sodium salts
and powdered
soda glass), cure accelerators (such a certain zinc chelates), and/or
combinations thereof
without limitation unless otherwise indicated in the following claims.
Materials made by such
processing steps and with such ingredients have been found to have excellent
flexibility down
to -10 C and buttery haptics.
Example 7
80 parts of ENR-50 is mixed with 21 parts of the cured resin of Example 4 in
the previous
section. It has been found that there is sufficient shear during the mixing of
the ENR-50 with
the cured resin of Example 4 that the cured resin is mechano-chemically broken
down (de-
crosslinked) and thus becomes a source of carboxylic acid functionality that
is capable of
curing the ENR-50. This mixture of elastomeric gum materials may be further
combined with
fillers, plasticizers, and functional additives to yield a compound that may
then be cured as an
elastomeric solid.
The molded materials produced according to Example 6 and Example 7 have
attributes that
allow them to be used as leather-substitute materials. The blend of a
relatively low Tg
materials such as ENR-50 with a relatively higher Tg material such as the
masticized resin
yields a bulk material with excellent haptics and low temperature flexibility
down to at least -
10 C. Furthermore, the bulk material glass transition temperature can be
lowered by
incorporating a plasticizer such as propylene glycol without negatively
impacting the tactile
properties of the material. Instead, it has been found that a plasticizer such
as propylene
glycol (which can be made with a catalytic process known as hydrogenolysis to
readily
convert plant-sourced glycerin and hydrogen to propylene glycol) acts as both
a plasticizer
and aid to the creation of "buttery" haptics by lowering the surface friction.
In these examples, it has been found that the combination of high molecular
weight ENR and
masticized resin yields an optimal balance of green strength, low temperature
flexibility, and
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room temperature flexibility. Without wishing to be bound by theory, it is
believed that there
may exist domains within the final compound that remain rich in the resin-
based starting
thermoset and domains that are more rich in ENR. The mixture of domains may
limit the
localized extensibility of the compound, thus reducing the sensation of
grippiness. In support
of this theory, remilled resin as illustrated in FIG. 15 was stirred into
ethanol overnight; the
resultant solution showed some small curdled material in the bottom of the
container that
would not dissolve. This suggests that during the remilling operation, a
portion of the
thermoset material is mechano-chemically modified through shear and once the
shear drops
below a certain threshold, the remaining thermoset material does not
experience sufficient
shear to break the B-hydroxyester crosslinks. Therefore, the de-crosslinking
is not
homogeneously distributed throughout the material; i.e. some crosslinked
domains survive
the remilling process. As a result, the combined ENR and remilled resin
compound will have
some portion of previously crosslinked resin that survive the mixing process
and act as
domains that impart a locally higher Tg and thus less grippy haptic.
In another illustrative embodiment it may be desirable to configure the
material such that it
exhibits a relatively high Tg, and one illustrative method for increasing the
Tg of an ENR-50
rubber compound is disclosed below, but other suitable methods for increasing
the Tg of an
ENR-50 rubber compound according to the present disclosure may be used without
limitation
unless otherwise indicated in the following claims. Generally, ENR-50 has a Tg
of -24 C as
prepared. It has been unexpectedly discovered that a standard compound based
on ENR-50
with mineral fillers (e.g., clay and talc) along with a curative that is made
in accordance with
methods disclosed elsewhere in this application; i.e., a reaction product of a
naturally
occurring polyfunctional carboxylic acid (e.g., citric acid) along with an
epoxidized
triglyceride (e.g., ESO) may be further made to have plastic-like attributes
such that the
resulting material may be configured as a rigid or semi-rigid material. In one
illustrative
embodiment, these attributes were found to arise when phytic acid is
incorporated into the
recipe at loadings as low as 2phr and then subjected to a heat treatment. Such
a compound
was mixed and molded and found to have initial properties of 11.9 MPa tensile
strength and
120% elongation. After heat treating at 100 C for 168hrs, the compound was
found to be a
rigid plastic with a strength of 14.8 MPa and an elongation of 16.7%. It was
found that
reheating the compound (from room temperature (e.g., ¨15 C-30 C) to 60 C)
decreased the
stiffness and increased the elongation; thus, the heat treatment did not
merely cause
embrittlement (characteristic of heat aging of elastomers) but rather caused a
dramatic shift in
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the Tg from the original -24 C to >20 C. Such a rigid or semi-rigid (e.g.,
plastic) material
may further be filled with fibrous reinforcements to further improve the
tensile strength of the
material.
5. Applicability
The recycling of thermoset materials is a particularly challenging problem for
the polymer-
materials industry. Some proposed solutions for this challenge have included
solvent-induced
depolymerization, grinding of waste and re-integration with new binder, and
thermal
depolymerization. None of these solutions are easy to integrate into existing
manufacturing
processes. In contrast, the mechanically induced de-crosslinking of the
thermoset material
according to this disclosure utilizes the very same equipment and methodology
used to mix
the material in the first place. Thereby, an article may be molded using low
percentages of
reclaimed material all the way up to 100% reclaimed material. Such materials
may be utilized
in articles substantially identical to articles manufactured with virgin
material.
In the manufacturing of leather-like materials, it has been advantageously
found that the
inclusion of at least some reclaimed and recycled material results in a sheet
product having a
naturally occurring texture that is particularly pleasing ¨ having surface
undulations on the
scale of 1-10 mm that do not require any texture in the mold. Such surface
undulations may
be similar to that exhibited by bison or buffalo leather products and is
highly desirable for
many applications.
The ability to integrate waste material (e.g., product trimming, flawed
articles, articles that
have reached the end of their useful life, etc.) into articles without
significant loss of
mechanical properties and without the requirement of additional virgin
material addition
enables closed-loop manufacturing in a way not previously envisioned for
thermoset
materials. Importantly, such materials may be still biodegradable and may be
sourced from
plant-based raw ingredients without the inclusion of petrochemically derived
precursors.
The use of pre-cured thermoset material as a curative for ENR is particularly
advantageous
from a processing standpoint. It has been found that the curative as disclosed
in Section 1 and
then applied in Section 3 may impart stickiness to some of the compounds,
especially during
mixing. The use of pre-cured themoset resin as disclosed herein significantly
reduces the
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stickiness of the batch during processing and likewise reduces the
tackiness/grippiness of the
molded article.
5. Foam Material
A. Background
Most resilient foam products that are commercially available are based on
synthetic
polymers, specifically polyurethane. A key attribute that differentiates so-
called memory
foam from other foam products is the glass transition temperature (Tg) of the
polymer. Rigid
foams are generally comprised of polymers with a Tg well above room
temperature, an
illustrative example of such a product is polystyrene foam (often used in
rigid insulation
boards and insulated drinking cups). Flexible and springy foams are generally
comprised of
polymers with a Tg well below room temperature, an exemplary example of such a
product is
a car door weather seal based on ethylene-propylene rubber (EPR/EPDM). Natural
products
may be likewise found in both rigid and flexible/springy categories. Balsa
wood is a
generally porous and foam-like material that is substantially rigid at room
temperature (e.g.,
¨15 C-30 C). Natural rubber latex may be foamed by either the Talalay or
Dunlop process to
make a flexible and springy foam product that is substantially comprised of
naturally
occurring polymers. To date, there is no widespread naturally occurring foam
that has a Tg
near room temperature (e.g., ¨15 C-30 C) to yield a lossy foam that is the key
attribute of
memory foam materials.
Natural materials that make flexible foam products today are often based on
natural rubber
latex. To make latex products stable to temperature excursions, the polymer
must be
vulcanized (i.e., crosslinked). Vulcanization of natural rubber may occur
through a few
known methods; most often sulfur vulcanization may be used, but peroxide or
phenolic cure
systems may likewise be used. Although sulfur and zinc oxide cure systems may
be capable
of vulcanizing natural rubber latex, very often other chemicals are added to
increase the cure
rate, limit reversion, and provide other functional benefits (e.g., anti-
oxidants, anti-ozonates,
and/or UV stabilizers). These additional chemicals may create chemical
sensitivities in
certain individuals. Also, natural rubber latex itself may cause allergic
reactions in certain
individuals due to the natural proteins that exist in the latex.
Similar natural rubber latex formulations may likewise be used as a glue for
fibrous mats to
create a resilient foam-like product. Notably, coconut fiber may be bonded
together by
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natural rubber latex into a non-woven mat to provide a cushion or mattress
material that is
substantially all-natural in origin. Despite various claims in the prior art
of being "all
natural," the cure system and additives to the natural rubber may contain
synthetic chemicals
that may create chemical sensitivities in certain individuals; furthermore,
the natural rubber
latex itself may cause allergic reactions in certain individuals due to the
residual protein.
Furthermore, footwear midsoles are most often made from EVA foam for
performance
footwear. EVA foams have low-density, high-energy resiliency, decent
compression set, and
are easy to form and process. EVA is a petrochemical polymer that is not bio-
based nor
.. biodegradable. Accordingly, it would be desirable to have a foam that meets
the energy
rebound (resiliency) and compression set attributes of EVA while being 100%
bio-based.
B. Summary
A foam product based on epoxidized vegetable oil is disclosed wherein the pre-
polymer
curative is likewise comprised of naturally occurring and naturally derived
products of
biological origin. The foam product disclosed is created without the use of
additional foaming
agent. The foamed product may be created with or without the requirement of
whipping in air
into the pre-cured liquid resin. The foam product disclosed may have a Tg near
room
temperature (e.g., ¨15 C-30 C), thus providing a lossy product. Additionally,
the foam
product may be formulated to have a Tg below room temperature (e.g., less than
¨23 C) to
provide a flexible, springy product. Memory foam attributes may be attained by
polymers
prepared according to this disclosure. Such polymers are reaction products of
the pre-polymer
curative as described herein above and epoxidized vegetable oils, reaction
mixtures may also
contain other natural polymers and modified natural polymers as described in
further detail
.. below.
In certain embodiments, the foam product may contain a certain fraction of
epoxidized
natural rubber. Notably, the process that creates epoxidized natural rubber
also reduces the
free protein that may create allergic reactions in certain individuals. The
reduction in allergic
response for epoxidized natural rubber compared to untreated natural rubber is
greater than
95%.
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Disclosed is a castable resin comprising EVO (and/or any suitable epoxidized
triglyceride as
disclosed above) combined with the pre-polymer curative (as disclosed above in
Section 1),
and in one illustrative embodiment ENR that has been solubilized in the EVO.
It has been found that a pre-polymer curative, as disclosed in Section 1, can
be created that
eliminates the risk of porosity when cured within a certain temperature range,
but that
evolves gas during the curing process when conducted within a second higher
temperature
range. Furthermore, the oligomeric pre-polymer curative may incorporate
substantially all of
the polyfunctional carboxylic acid so that no additional solvent is required
during the curing
process. For example, citric acid is not miscible in ESO but they may be made
to react with
each other in a suitable solvent. The amount of citric acid may be selected so
that the pre-
polymer curative is created so that substantially all of the epoxide groups of
the ESO in the
pre-polymer curative are reacted with carboxylic acid groups of the citric
acid. With
sufficiently excess citric acid, the pre-polymerization extent may be limited
so that no gel
fraction is formed. That is, the target pre-polymer curative is a low
molecular weight
(oligomeric) citric-acid capped ester-product formed by the reaction between
carboxylic acid
groups on the citric acid with epoxide groups on the ESO.
Illustrative oligomeric pre-polymer curatives may be created with weight
ratios of ESO to
citric acid in the range of 1.5:1 ¨ 0.5:1. If too much ESO is added during pre-
polymer
curative creation, the solution may gel and further incorporation of ESO to
create the target
resin becomes impossible. Note that on a weight basis, stoichiometric
equivalent amounts of
epoxide groups on the ESO and carboxylic acid groups on the citric acid occur
at a weight
ratio of 100 parts of ESO to about 30 parts of citric acid. A ratio of
ESO:citric acid above
1.5:1 may build a pre-polymer curative with excessive molecular weight (and
hence
viscosity) which limits its usefulness as a casting resin. If the ratio of
ESO:citric acid is below
0.5:1 it has been found that there is so much excess citric acid that after
solvent evaporation,
ungrafted citric acid may precipitate out of solution.
In addition to controlling the ratio of ESO to citric acid, according to the
present disclosure it
has been found that selective control of the amount of alcohol used as a
solvent may also be
used to tailor the physical properties of the resulting elastomeric foam. It
has been found that
the alcohol solvent may itself be incorporated into the elastomer by forming
ester linkages
with the polyfunctional carboxylic acid that are reversible and thus gas-
evolving when the
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material is cured at a temperature higher than that required to make a
porosity-free product. A
mixture of two or more solvents may be used to tailor the amount of grafting
of an alcohol-
containing solvent onto the citric acid-capped oligomeric pre-polymer
curative.
For example, and without restriction or limitation unless otherwise indicated
in the following
claims, isopropyl alcohol (IPA) or ethanol may be used as a component of a
solvent system
used to miscibilize citric acid with ESO. IPA or ethanol are capable of
forming an ester
linkage via a condensation reaction with citric acid. Since citric acid has
three carboxylic
acids, such grafting reduces the average functionality of the citric acid
molecules that are
reacting with the ESO. This is beneficial in creating an oligomeric structure
that is more
linear and therefore less highly branched. Acetone may be used as one
component of a
solvent system used to miscibilize citric acid with ESO, but unlike IPA or
ethanol, acetone
itself is not capable of being grafted onto the citric acid-capped oligomeric
pre-polymer
curative. Indeed, during creation of the oligomeric pre-polymer curative it
has been found
that the reactivity of the pre-polymer curative is determined, in part, by the
ratio of IPA or
ethanol to acetone that may be used to solubilize citric acid with ESO. That
is, in reaction
mixtures with the similar amounts of citric acid and ESO, a pre-polymer
curative created
from a solution with a relatively high ratio of IPA or ethanol to acetone
creates a lower
viscosity product than pre-polymer curative created from a solution with a
relatively low ratio
of IPA or ethanol to acetone under similar reaction conditions. Also, the
amount of IPA or
ethanol grafted on the pre-polymer curative determines the extent to which
such IPA or
ethanol is evolved when the formulated resin is foamed at a temperature higher
than that
required to make a porosity-free resin product.
C. Illustrative Methods and Products
Illustrative blends that create resilient memory foams have been created from
a combination
of inputs that include a pre-polymer curative, a liquid blend of epoxidized
natural rubber and
epoxidized vegetable oil and may contain unmodified epoxidized vegetable oil.
In a first illustrative embodiment of a foam material, the resilient memory
foam is produced
using a pre-polymer curative creation and by dissolving 50 parts of citric
acid in 125 parts of
warm IPA, accelerated by mixing (again with reference to FIG.1). After
dissolution of the
citric acid, 50 parts of ESO is added to the stirring solution. The solution
is preferably mixed
and reacted at temperatures of 60 C ¨ 140 C with optional use of mild vacuum
(50 ¨300
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Ton). One illustrative batch was mixed in a jacketed reactor vessel with a
jacket temperature
of 120 C (solution temperatures of ¨70 C ¨ 85 C) and the citric acid grafting
onto ESO
occurred concurrently with IPA evaporation. At the end of the reaction
sequence it was
discovered that roughly 12 parts of IPA was grafted onto the combined 100
parts of ESO and
citric acid. Accordingly, temperatures above the boiling point of IPA and
application of
vacuum could no longer yield IPA condensate in the condensing system.
Calculations reveal
that of the starting carboxylic acid sites on the citric acid, roughly 31%
reacted with epoxide
groups on the ESO (assuming all of the epoxides were converted during the
reaction to ester
linkages), roughly 27% of the carboxylic acid sites reacted with IPA to form
pendant esters,
and roughly 42% remain unreacted and available for crosslinking the resin in a
subsequent
processing step. However, these calculations are for illustrative purposes
only and in no way
limit the scope of the present disclosure unless otherwise indicated in the
following claims.
In a second illustrative embodiment of a foam material, the resilient memory
foam was
created via a rubber-containing resin precursor. Epoxidized natural rubber may
be included in
resin-based formulations at levels below twenty-five weight percent (25 wt%)
and still yield a
pourable liquid. Creation of the rubber-containing precursor may be done in
two-stages
without requiring the use of a solvent for rubber dissolution. In the first
stage 100 parts of
epoxidized natural rubber (ENR-25) are mixed with 50 parts of ESO using rubber
mixing
techniques (a two-roll mill or internal mixer). This yields a very soft gum
that cannot
effectively be further mixed on rubber processing equipment, but with the
application of heat
(e.g., 80 C) additional ESO may be mixed into the rubber with a Flacktek
Speedmixer or
alternative low-horsepower equipment (e.g., a sigma-blade mixer) to create a
flowable liquid
containing 25% ENR-25 and 75% ESO.
A third illustrative embodiment of a foam material may also produce a
resilient memory
foam-type creation. In this embodiment, the foamable resin is produced via
mixing and
curing. For this illustrative embodiment, 40 parts of pre-polymer curative
from the first
illustrative embodiment of a foam material was added to 80 parts of rubber-
containing resin
from the second illustrative embodiment. The resulting combination was then
mixed with a
Flacktek Speedmixer until a homogeneous solution was obtained (about 10
minutes of
mixing). This resin was cured using the following two procedures:
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1. Resin cured on 200 C (nominal temperature) hot griddle (PTFE coated)
just like a
pancake. The material foamed to a relatively homogenous article with memory-
foam
characteristics; specifically, lossy behavior. A depiction of the resulting
material is shown
in FIG. 13.
2. Resin was vacuum degassed after mixing and placed on the same 200 C hot
griddle. In
this instance, porosity was observed over the heating element (measured
temperature
210 C) but no porosity was observed over the region of the griddle without the
heating
element (measured temperature 180 C). Depictions of the resulting materials
are shown
in FIG. 14.
From these two procedures, it is clear that there may be two sources of
porosity. One source
may involve small bubbles of air that are incorporated during mixing.
Additional
experimentation has shown that the presence of ENR-25 in the resin is an
important
contributor to stabilizing this incorporated air and preventing bubble
coalescence during the
.. curing stage. The second source of porosity is evolved gas, likely removal
of the grafted IPA,
at temperatures at or above 200 C.
As previously described, certain catalysts are known in the art to speed up
the carboxylic acid
addition to epoxide groups and such may be used in formulating recipes
according to the
.. present disclosure without limitation unless otherwise indicated in the
following claims.
Referring now to FIGS. 20 & 20A, shown therein is a foam that is suitable for
certain
footwear applications, wherein the foam is substantially or completely free of
petrochemical
inputs and does not require petrochemical blowing agents. A slab of such foam
is shown
generally in FIG. 20 and a detailed view of an exterior surface and a cross-
section thereof is
shown in FIG. 20A. This foam is based on epoxidized natural rubber and is
cured with a
curative that is made according to the preceding description. Additionally,
this foam may be
made into slabs with a thickness between approximately 2.5mm and 25mm in which
the heat
transfer may be accomplished with heated plates applied to the two planar
surfaces.
Referring now to FIG. 21, which provides a depiction of one illustrative
embodiment of a
method of making such a foam, the heated plate on top (floating platen 210)
may be sized
and/or configured to exert between 0.5p5i and 2.0psi vertical pressure on the
expanding foam
200 to keep it from developing non-planar attributes and to keep any large air
pockets (that
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may be introduced by mixing and/or sheeting) from growing into large defect
sites. The
expanding foam 200 may be positioned between the floating platen 210 and
lifting platen
220. However, other methods of making a foam with the desired characteristics
and
according to the present disclosure without limitation unless otherwise
indicated in the
following claims.
Ingredient Parts per Hundred Rubber Ingredient Class
ENR-25 100 Polymer
Cork powder 0-40 Filler
Starch 0-100 Filler
Precipitated Silica 0-10 Filler
Epoxidized Soybean Oil 0-10 Plasticizer
Castor Oil 0-10 Plasticizer
Plant-Based Wax 0-1 Release Aid
Curative (as defined 5-20 Curative
herein above)
Table 3¨Illustrative Ranges of Ingredients.
As shown in Table 3, a foam produced according to the present disclosure may
include a
varying array of ingredients, and the specific ingredients and their relative
proportions within
the foam in no way limit the scope of the present disclosure unless otherwise
indicated in the
following claims. In one illustrative embodiment, epoxidized natural rubber 25
(ENR-25)
may be mixed with fillers such as cork powder, corn starch, silica,
plasticizing oils, and
curative prepared according to the present disclosure as described in detail
herein above. This
mixture may be sheeted out on a two-roll mill or calender to a thickness
roughly half of the
final target thickness. The calendered sheet may be placed between two heated
steel plates for
both curing (vulcanization) and foaming. In one illustrative embodiment, a
multiple-daylight
platen press, such as that shown in FIG. 16, may be used in which the weight
of a single
platen exerts between 0.5p5i and 2.0psi on the calendered sheet.
While the mixture expands, the heat from the top (floating) platen 210 and
bottom (fixed), or
lifting platen 220 convey heat into the compound to simultaneously cure the
rubber. The cure
time may be directly impacted by the thickness of the sheet and may be between
5 minutes
and 2 hours (wherein longer cure times may be required for thicker slabs). The
curing
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temperature is preferably between 120 C and 180 C, or even more preferably
between 130 C
and 170 C, and even more preferably between 140 C and 160 C without limitation
unless
otherwise indicated in the following claims. After curing, a slab of foam made
according to
the present disclosure may exhibit performance attributes as shown in Table 3.
However, a
.. foam produced according to the present disclosure may be configured to
exhibit other
properties and/or other values and/or ranges of the properties shown in Table
4 without
limitation unless otherwise indicated in the following claims.
Density Resiliency Dynamic Compression Set Energy
Efficiency
0.35-0.55 g/cm3 >20% >10% >60%
Table 4¨Illustrative properties of a foam made according to the present
disclosure.
Foams made according to this disclosure may be used in footwear midsoles,
insoles, and
foam padding for tongues at various thicknesses. Of particular utility may be
the use of foams
according to this disclosure in footwear midsoles. Foams produced according to
the present
disclosure may be applicable to other products without limitation unless
otherwise indicated
in the following claims.
D. Applications/Additional Illustrative Products
Materials according to this disclosure may be used as flooring, exercise mats,
bedding, shoe
insoles, shoe outsoles, or sound absorption panels without limitation unless
otherwise
indicated in the following claims.
Materials according to this disclosure may be molded into complex three-
dimensional articles
and multi-laminated articles. Three-dimensional articles may also consist of
multiple material
formulations arranged at various locations within an article to provide
functionality required
for each location.
The resilient memory foam based on vegetable oil may be used in applications
where
polyurethane is used today. Such applications may include shoes, seating,
flooring, exercise
mats, bedding, sound absorption panels, and the like without limitation unless
otherwise
.. indicated in the following claims. Many of these articles are consumable
items that if made
from synthetic polyurethane foams are non-biodegradable and are non-
recyclable. If such
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items are made from the material disclosed herein, they would be biodegradable
and thus not
create a disposal problem.
6. Additional Articles
SUMMARY
One object of various embodiments of the present disclosure is to provide
methods of
manufacture for various articles (including but not limited to footwear unless
otherwise
indicated in the following claims), wherein an article may be comprised of
various types of
materials that all utilize the same class(es) of polymer(s) for all functional
components
therein. That is, the continuous polymer phase of all types of materials are
compatible with
each other.
Additionally, another object of illustrative embodiments of the present
disclosure is to
provide such types of materials that all utilize the same class(es) of
polymer(s) wherein said
polymer(s) are bio-based (i.e., coming from agricultural sources, either in
entirety or in
substantial majority) with nominal or no detectable synthetic and/or petroleum-
based
compounds. Such types of materials include, but are not limited to unless
otherwise indicated
in the following claims: a foam material that is applicable to midsole and/or
insole
components, a solid molded material that is applicable to the outsole, a sheet-
good material
that is applicable to the upper components, an adhesive material that may be
used to bond
components together, a coating material that may be used to provide preferred
haptics and
possibly coat textile material(s), a textile material (used as a knit upper
for example or a
backer for the sheet-good material), and/or a rigid or semi-rigid material
(which may be used
for various components such as buckles, clasps, eyelets, zippers, loops, eye
stays, clips,
and/or similar components without limitation unless otherwise indicated in the
following
claims).
Another object of illustrative embodiments of the present disclosure is to
provide a
mechanical processing technology that may render said materials reformable
into a new
article comprising one homogeneous blend of the various types of input
materials used in the
entire article. It is a further object of illustrative embodiments of the
present disclosure to
provide a mechanical processing technology that utilizes mechano-chemical
reactions that
render the blended types of input materials capable of being remolded (using
thermoset
molding chemistries) into a new article. Other objects of illustrative
embodiments of the
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present disclosure may be utilized, inherent, and/or expressed herein without
limitation unless
otherwise indicated in the following claims.
Materials that may be suitable for inclusion in such illustrative embodiments
of a footwear
article include, but are not limited to unless otherwise indicated in the
following claims, those
manufactured according to technologies disclosed in US10,400,061;
US10,882,950;
US10,882,951, and other related pending applications by the same inventor(s).
Such
materials may utilize a mechano-chemically reversible thermoset curative.
Materials utilizing
this technology (both epoxidized polymer(s) and B-hydroxyesters as cure sites)
are able to be
homogeneously combined regardless of the starting form; either sheet good,
molded
component, foam, coating material, rigid or semi-rigid material, or adhesive
interlayer
without limitation unless otherwise indicated in the following claims.
Generally, at least six types of materials may be manufactured according to
the present
disclosure, which materials may be used in various articles as disclosed
herein or as suitable
for the particular material or combinations of materials without limitation
unless otherwise
indicated in the following claims. These various material types may share at
least a common
chemistry in that each may include B-hydroxyester linkages, and that in
various illustrative
embodiments each type of material may be constructed with only naturally
occurring
compounds (and without use of any animal-hide leather) yet exhibit the
performance
characteristics desired for a wide range of applications. That is, the
materials may be
completely petro-chemical, synthetic chemical, and/or animal-hide leather free
yet
simultaneously perform similar to or better than the prior art materials. The
commonality in
chemistry among the various materials disclosed herein may result in various
advantages,
including but not limited to the miscibility of virtually any combination
and/or configuration
of the various materials during a mechano-chemical process (such as that
disclosed herein for
recycling materials) without limitation unless otherwise indicated in the
following claims.
The materials may be bonded to one another during processing in any order,
number, layers,
thicknesses, configuration, etc. suitable for the material and particular
application thereof
without limitation unless otherwise indicated in the following claims.
A first material may be configured as a leather-like material as described in
detail herein
above, wherein the leather-like material may serve as a substitute for
applications currently
served by synthetic leathers and/or animal-hide leathers without limitation
unless otherwise
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indicated in the following claims. Such a material may be comprised of a
thermosetting
elastomer that is crosslinked with B-hydroxyester linkages, wherein said first
material is
defined as being a leather-like material with a glass transition temperature
generally below
room temperature (e.g., less than ¨ 23 C), wherein said first material may be
configured as
generally planar and having a thickness between about 0.3 mm and 2.5 mm but
without
limitation unless otherwise indicated in the following claims.
A second material may be comprised of the same thermosetting elastomer that is
crosslinked
with B-hydroxyester linkages, wherein the second material may be defined as
being a foam
material with a glass transition temperature generally not greater than room
temperature or
just above room temperature (e.g., around ¨23 C or between ¨20 and ¨30 C) and
having a
density less than 0.7 g/cc but without limitation unless otherwise indicated
in the following
claims.
A third material may be comprised of the same thermosetting elastomer that is
crosslinked
with B-hydroxyester linkages, wherein the third material may defined as being
a molded
elastomer material with a glass transition temperature generally not greater
than room
temperature or just over room temperature (e.g., around ¨23 C or between ¨20
and ¨30 C),
wherein the third material may be cast and/or molded in a three-dimensional in
shape but
without limitation unless otherwise indicated in the following claims.
A fourth material may be comprised of the same thermosetting elastomer that is
crosslinked
with B-hydroxyester linkages, wherein the fourth material may be defined as
being a coating
material with a glass transition temperature generally below room temperature
(e.g., less than
¨23 C), wherein the fourth material may be configured with a thickness from 10
to 100
microns but without limitation unless otherwise indicated in the following
claims.
A fifth material may be comprised of the same thermosetting elastomer that is
crosslinked
with B-hydroxyester linkages, wherein the fifth material may be defined as
being an adhesive
material with a glass transition temperature generally below room temperature
(e.g., less than
¨23 C), and wherein the fifth material has a thickness of lmm or less but
without limitation
unless otherwise indicated in the following claims. Further, it is
contemplated that the
adhesive material may generally be positioned between two substrates, wherein
either
substrate may be one of the other materials disclosed herein but without
limitation unless
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otherwise indicated in the following claims.
A sixth material may be comprised of the same thermosetting elastomer that is
crosslinked
with B-hydroxyester linkages, wherein the sixth material is defined as being a
rigid or semi-
rigid material with a glass transition temperature generally greater than room
temperature
(e.g., greater than ¨23 C), and wherein the sixth material is substantially
non-crystalline in
structure but without limitation unless otherwise indicated in the following
claims.
These six materials may be bonded to one another in nearly any combination to
fabricate an
article having a desired set of characteristics and/or functional attributes.
That is, the first
material may be bonded to the second material, third material, fourth
material, fifth material,
and/or sixth material; the second material may be bonded to the third
material, fourth
material, fifth material, and/or sixth material; the third material may be
bonded to the fourth
material, fifth material, and/or sixth material; the fourth material may be
bonded to the fifth
material and/or sixth material; and the fifth material may be bonded to the
sixth material in
any suitable combination, ordering, and/or layering without limitation unless
otherwise
indicated in the following claims. Additionally, an article may include more
than one layer of
a specific type of material separated by layers for other types of material
(e.g., a layer of the
second material sandwiched between two layers of the first material) in any
suitable
configuration without limitation unless otherwise indicated in the following
claims. The
common chemistry among the six materials, and particularly the B-hydroxyester
linkages,
allow any and all combinations of the six materials to be miscible during
certain types of
recycling as described in detail below, including but not limited to mechano-
chemical
processing (which may serve to selectively and/or reversibly break or the B-
hydroxyester
linkages or "de-crosslink" the material) unless otherwise indicated in the
following claims.
DETAILED DESCRIPTION
An illustrative embodiment of a footwear article produced according to the
present disclosure
may contain one or more types of materials that utilize a polymer matrix that
is molded and
cured wherein B-hydroxyesters are crosslinks between epoxidized polymer
inputs. An
illustrative embodiment of a footwear article according to this disclosure may
contain textile
components without limitation as well unless otherwise indicated in the
following claims. In
one illustrative embodiment, said textile components are preferably made from
bio-based
inputs such as: cotton, regenerated cellulose, various animal fibers (wool,
silk, alpaca fiber,
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etc.), protein fibers (soy protein, casein), and man-made bio-based fibers
(e.g.
polyhydroxyalkanoates, polylactic acid) without limitation unless otherwise
indicated in the
following claims. For certain applications it may be preferable to utilize
foams based on
epoxidized natural rubber (ENR) as the continuous polymer matrix that are
cured
(vulcanized) via B-hydroxyesters. In one illustrative application a preferred
curative may be
prepared according to US10,400,061 which is incorporated by reference herein
in its entirety.
Mechano-chemical recycling of footwear articles as manufactured according to
illustrative
embodiments of the present disclosure may involve at least two steps: (1) the
pre-shredding
.. of the footwear article; (2) subjecting the shredded material to high-shear
mixing (such as
may be accomplished by a two-roll mill as is commonly used in rubber mixing or
an internal
mixer as is commonly used in rubber mixing); (3) shaping the homogenously
mixed
elastomeric material to an appropriately sized pre-form (whether through
calendering or
extrusion or other suitable process); and/or 4) molding a desired article
through heat and
pressure to yield a formed thermoset material.
I. Foams
Foams are used in footwear components as midsoles, insoles, tongue padding,
and/or around
the cuff area. Foams of various thicknesses and densities are possible within
the inventive
framework disclosed herein. In one illustrative embodiment, foams may be
manufactured by
mixing an ENR-based batch of material containing a substantial (>10wt%)
content of cork
powder. It has been discovered that certain kinds of cork powder can be
incorporated into
ENR-based recipes and entrain trapped air that may expand upon low-pressure
curing to yield
foams with densities less than 0.75 g/cc. Even more preferably, certain
recipes may be
subject to low-pressure curing and achieve densities less than 0.6 g/cc. Even
more preferably,
certain recipes have discovered that, even though they contain no chemical
blowing agents,
still achieve densities less than 0.5 g/cc.
In one particular illustrative embodiment, a recipe containing 100 parts of
ENR was
combined with a total of 35 parts of various cork powders along with 15 parts
of natural
plasticizers, 10 parts of precipitated silica, and curative (as further
described in US
10,400,061) to yield a recipe that was sheeted out and cured with low pressure
(0.5-4 psi), It
has been found that pressure-free curing may result in sheets that are not
smooth and may
have large trapped-air pockets. Low-pressure curing may result in an optimal
balance of
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sufficient pressure to reduce the propensity of large trapped-air pockets to
expand while still
allowing for the expansion of air to create pores on the 0.1-3 mm size scale.
Curing
temperatures may be 120 C - 180 C, or even more preferably between 130 C - 170
C, and in
some cases between 140 C - 160 C. Concurrent with the curing process is the
expansion of
the entrained air to form the porosity. That is, the sheet (or article) may be
placed in an oven
at one (higher) density and the sheet (or article) expands with the
application of heat to reach
the target thickness and a second (lower) density. Immediately after
expansion, and even
during expansion, the curing reaction may be instigated and may act to
chemically fix the
new dimensions in-place. In one illustrative embodiment, a sheet that is
placed into an oven
or between hot plates at 5mm thickness may expand to a sheet that is 9-11mm in
thickness
after expansion and curing. Surprisingly, it has been found that vertical
pressure applied to a
preform may be sufficient to constrain lateral growth while allowing vertical
growth. That is,
the thickness of the sheet may grow while the lateral dimensions remain
relatively
unchanged.
If oven curing is used, it may be preferable to have a preheated metal plate
to place on top of
the foaming sheet to apply the target pressure range (0.5-4 psi). In one
illustrative
embodiment, a custom molded shape may be created by manufacturing a preform of
dimensions roughly half as thick as the final target thickness (including any
convolutions or
variations in thickness required), placing a preheated metal mold on the top
of preform, and
allowing said preform to expand to the final target shape. In one illustrative
embodiment, said
custom molded shape may be a shoe midsole. In this instance, the midsole
preform may be
created by pressing the rubber compound into a shape that is substantially
similar to the
contours of the final midsole - but roughly half of the final target
thickness. The midsole
preform may then be placed between two heated metal molds (one side may be a
simple
plate) to both foam the material and cure the material concurrently. The heat
from the metal
molds (again, one side may be a simple plate) will cause the entrained air to
expand and
increase the thickness of the rubber, reducing the density, and the rubber
will cure.
For articles that do not require complex contours, the creation of sheet
preforms may be
created by calendering or extruding the rubber compound to a thickness that is
less than the
final target thickness. That is, a 5mm calendered sheet may foam to a final
thickness of 9-
11mm. In some instances, the thickness of the final foam would require a
preform thickness
that is beyond the range of control that is possible with calendering. In such
cases, sheet
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extrusion may be used to make a sheet preform that is substantially free of
large trapped-air
pockets.
Outsoles
Outsoles used in many footwear articles are 3-dimensionally molded components
that
comprise features that provide traction, provide wear material, and interface
with the other
components of the shoe. Rubber outsoles are well known in the art; they are
often made of
thermoset (i.e. vulcanized) elastomers but may also be made from thermoplastic
elastomers
(TPE) - of which there are many subtypes that may be suitable, including but
not limited to:
ethylene vinyl acetate copolymers (EVA), styrene butadiene styrene (SBS),
styrene ethylene
butadiene styrene (SEBS), other styrenic block copolymers (generically TPS),
polyether
block amide (TPA), copolyester (TPC), thermoplastic polyurethane (TPU),
thermoplastic
polyolefins (TPO). Additionally, outsoles may be made from thermoplastic
vulcanizates
(TPV); compounds that contain crosslinked rubber within a thermoplastic
matrix. The highest
.. performing outsoles are made from thermoset elastomers. Among the most
common
thermoset elastomers that may be used for outsoles, natural rubber (NR),
styrene butadiene
rubber (SBR), butadiene rubber (BR), and ethylene propylene diene monomer
(EPDM) are
the most widely used. Polychloroprene (CR) or acrylonitrile butadiene rubber
(NBR) may be
used for oil-resistant sole formulations.
According to an illustrative embodiment of the present disclosure, a preferred
thermoset
elastomer outsole formulation may be based on epoxidized natural rubber (ENR).
ENR is
commercially available in two grades: ENR-25 and ENR-50, which are
differentiated by their
respective degrees of epoxidation; 25% of the double bonds are converted to
epoxides in
ENR-25 while 50% of the double bonds are converted to epoxides in ENR-50.
According to
one illustrative embodiment, ENR-25 may be used for the outsole base rubber.
ENR may be
crosslinked (vulcanized) through means known in the art for unsaturated
elastomers;
including but not limited to sulfur vulcanization, peroxide vulcanization,
alkylphenol
vulcanization (so-called "resin cure"), and radiation vulcanization.
Additionally, because
ENR contains epoxy functional groups, there are other cure mechanisms that may
be used
that are uniquely suited to reactions with the epoxy functionality.
Polyfunctional amines,
polyfunctional acids, and polyphenol compounds may all be used to crosslink
epoxidized
polymers such as ENR. Among simple polyfunctional molecules that may be used
to
crosslink ENR, the bio-based PriamineTM molecules from Croda - all
polyfunctional amines -
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are one pathway. Another group of polyfunctional molecules that may be used to
crosslink
ENR are the polyfunctional carboxylic acids. For certain illustrative
embodiments, preferred
naturally occurring or naturally derived polyfunctional carboxylic acids
include, but are not
limited to unless otherwise indicated in the following claims, citric acid,
tartaric acid,
succinic acid, malic acid, maleic acid, oxalic acid, azelaic acid,
dodecanedioic acid, malonic
acid, sebacic acid, glutaric acid, glucaric acid, fumaric acid, crocetin,
muconic acid,
citraconic acid, mesaconic acid, itaconic acid, glutinic acid, glutamic acid,
aspartic acid,
acetonedicarboxylic acid, aconitic acid, agaric acid, and phytic acid. Another
class of
potential curatives are those that are reaction products between a
polyfunctional naturally
occurring carboxylic acid and an epoxidized plant oil; such reaction products
are further
disclosed in US 10,400,061.
When outsoles are manufactured with certain classes of curatives according to
this disclosure,
those compounds are able to be recycled according to mechano-chemical
processing and are
miscible with other articles, whether they be foams or sheet goods, that
utilize closely related
cure systems and polymer types. For example, an outsole that is manufactured
with ENR that
is cured with polyfunctional carboxylic acids may be mechno-chemically
recycled
concurrently (and miscibly) with a foam or sheet-good (used as a shoe upper)
that also is
made using ENR that is cured with polyfunctional carboxylic acids. This is
true whether the
ENR of one component (or subcomponent) is ENR-25 and another component (or
subcomponent) of the shoe utilizes ENR-50 as the base rubber. Furthermore, ENR-
based
components (or subcomponents) may be mechno-chemically processed concurrently
(and
miscibly) with materials that are reaction products between polyfunctional
carboxylic acids
and epoxidized plant oils. Various types of such mechano-chemical processing
are disclosed
in US 10,882,951.
Outsole thermoset elastomer compounds formulated according to this disclosure
may utilize
fillers that are only bio-based and mineral based. Non-marking soles may be
formulated
without carbon black as a filler; instead they may use precipitated silica as
the primary
reinforcing agent. Alternatively, rice husk ash may be used as an alternative
silica source that
imparts similar primary reinforcing benefits. In some illustrative
embodiments, mineral fillers
that may be used include talc, mica, wollastonite, clay(s), sepiolite,
muskovite, and other
silicates and aluminates. In some illustrative embodiments that do not require
translucency,
agricultural byproducts may be used as fillers. Common agricultural byproducts
include, but
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are not limited to, materials such as cork powder, ground rice hulls, ground
coir fiber,
cellulosic powders, various ground nut powders, and ground grasses (e.g.
miscanthus
powder). In general, high performance outsole compounds may contain some
primary
reinforcing filler(s) and may contain various extending fillers that improve
processing but do
not significantly impact strength and abrasion performance attributes.
III. Manufacture of adhesive
Many types of footwear are constructed using adhesives. Adhesives may serve as
fixturing
aids to supplement sewing, they may be the primary attachment medium between
midsoles
and shoe uppers (and/or other footwear/article components), they may be the
primary
attachment medium between midsoles and outsoles (and/or other footwear/article
components), and they may be used to secure foxing or other elements to the
outside of the
shoe surface. Many adhesives in use for footwear construction are elastomeric
and function
as contact adhesives (with high initial tack). Many are solvent-based to
facilitate dispensing
and spreading the adhesive. Many are heat-cured thermosets. Most all adhesives
in current
use are petrochemical-based.
According to the present disclosure, am entire class of adhesives based on
illustrative
embodiments of bio-based resins may be used in various articles/footwear. In
one illustrative
embodiment, the adhesive may be a 2-part (2K) thermosetting system that
comprises a
curative prepared as disclosed in US 10,400,061 and an epoxidized plant-based
oil. In one
illustrative embodiment, the adhesive is solvent-free and substantially
petrochemical-free. In
one illustrative embodiment the epoxide & carboxylic acid reaction is
catalyzed to allow for a
thermosetting reaction to occur at ¨100 C -150 C in less than 30 minutes to
yield a
sufficiently vulcanized adhesive. In one illustrative embodiment, the adhesive
may be
catalyzed before usage so that temperatures lower than 100 C and times less
than 30 minutes
are sufficient to cure the adhesive.
In another illustrative embodiment of a suitable adhesive prepared according
to the present
disclosure, the adhesive may be a 1-part (1K) thermosetting system that
comprises a material
that is partially reacted to completion at one temperature (e.g. a first
reaction temperature of
¨40 C-60 C) and then cooled to a temperature for storage that is less than
room temperature
(e.g., less than ¨ 23 C) and preferably stored at refrigerated temperatures
(e.g., less than
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¨5 C), and even more preferably stored at deeper freezing temperatures (e.g.,
less than ¨ -
15 C). This 1K thermosetting system may be reacted at the first reaction
temperature with a
naturally-occurring polyfunctional carboxylic acid and an epoxidized plant-
based
triglyceride. At this first reaction temperature, the naturally-occurring
polyfunctional
carboxylic acid (e.g. citric acid) may be miscibilized with the epoxidized
plant-based
triglyceride (e.g. epoxidized soybean oil, ESO) with a miscibilizing solvent
(e.g. acetone,
isopropyl alcohol, or ethanol). At the first reaction temperature, it has been
found that a stable
intermediate product may be created that creates a pre-polymer in
stoichiometric balance but
that is not completely polymerized. After that first reaction is progressed
sufficiently - in one
illustrative embodiment this may take 16-32 hours, or more preferably this may
take 20-28
hours - the temperature may be lowered to a second temperature at which
residual
miscibilizing solvent may be vacuum extracted. This second temperature may be
between
¨15 C - 40 C, or more preferably between ¨20 C - 30 C. At this second (lower)
temperature,
the reaction rate may be considerably slowed such that the solvent may be
removed without
causing excessive pre-polymer growth (and thus viscosity increase). After the
solvent has
been removed (which in on illustrative embodiment may be performed by vacuum),
the
reaction product may be stored at sub-ambient temperatures (as already
described). This 1K
thermosetting adhesive system may be applied to various articles, article
components, and/or
footwear components and then cured (vulcanized) at ¨100 C - 150 C in less than
30 minutes
to set the adhesive joint. In one illustrative embodiment, the adhesive may be
catalyzed
before usage so that temperatures lower than 100 C and times less than 30
minutes are
sufficient to cure the adhesive.
IV. Coated textiles
Generally, for some applications it may be desirable to configure one or more
portions of an
article as a coated textile. Specifically, but without limitation unless
otherwise indicated in
the following claims, all or a portion of a shoe upper may be comprised of a
coated textile.
In an illustrative method for manufacturing such a coated textile, a resin
prepared according
to the present disclosure may be diluted in a solvent. The resulting solution
may be applied to
a fabric and/or textile via any suitable method using any suitable apparatus
unless otherwise
indicated in the following claims. It is contemplated that for some
applications the solution
may be sprayed, rolls, or padded onto the fabric and/or textile.
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After the solution is applied to the fabric and/or textile, the solvent may be
allowed to
evaporate and the resin may be cured. The solvent evaporation may be achieved
under
ambient pressure and/or temperature or under reduced pressure and/or increased
temperature
without limitation unless otherwise indicated in the following claims. The
resin cure may be
achieved under ambient pressure and/or temperature or under increased
temperature and/or
pressure without limitation unless otherwise indicated in the following
claims.
In one illustrative embodiment of a method of manufacturing a coated fabric
and/or textile,
but without limitation unless otherwise indicated in the following claims, the
coated fabric
and/or textile may be manufactured without a solvent or with a minimal amount
of solvent. In
such a method, an aqueous emulsion may be prepared with a resin configured as
those
previously described herein above, wherein the aqueous emulsion may
subsequently be
applied to the fabric and/or textile. In such a method, the aqueous emulsion
may be prepared
using a solvent-free or solvent-poor resin that may be mixed under relatively
high-shear
conditions with a suitable surfactant. Utilizing the proper amount of dilution
of resin in the
aqueous emulsion and proper application of the aqueous emulsion to the fabric
and/or textile
(e.g., small enough emulsion droplets, flow rates and flow characteristics of
aqueous
emulsion, etc.) may result in the desired attributes of the coated fabric
and/or textile (e.g.,
adequate coverage, penetration of the fabric and/or textile, etc.).
After application of the aqueous emulsion to the fabric and/or textile, the
treated fabric and/or
textile may be allowed to dry under ambient pressure and/or temperature or
under reduced
pressure and/or increased temperature without limitation unless otherwise
indicated in the
following claims. The resin cure may be achieved under ambient pressure and/or
temperature
or under increased temperature and/or pressure without limitation unless
otherwise indicated
in the following claims.
The resulting coated textile and/or fabric may exhibit various desirable
attributes, including
but not limited to, increased waterproof attributes, increased durability,
increased strength,
and/or combinations thereof unless otherwise indicated in the following
claims.
V. Integration into footwear/articles (examples of various styles)
Footwear is often created by combining multiple material types; most often
from various
material families. In some instances, the various material types (foam,
fabric, strapping, etc.)
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may be made from the same (or closely related) material families. For example,
a shoe may
use a polyester fabric upper, be closed with polyester fiber laces, it may use
a polyester co-
polymer foam, and perhaps could even use a polyester co-polymer thermoplastic
elastomer
outsole. In such instances, the entire shoe (made of related thermoplastics)
could
hypothetically be recycled by melting all the constituents and molding a new
article (shoe
component or alternative article) out of the blended material. In such a case,
there may be
some limitations in regards to the performance suitability of the available
options for the
various components when trying to keep all the materials in the same family.
Additionally,
there may be certain components (such as those listed above, but without
limitation unless
otherwise indicated in the following claims) that are better served by
thermoset polymers
instead of thermoplastic polymers. Also, the most commonly used thermoplastic
polymers
used in footwear components are neither biobased nor biodegradable.
An illustrative embodiment of the present disclosure provides for the
combination of multiple
material types drawn from a common family of thermosetting polymers. In
addition,
illustrative embodiments of the thermosetting polymers of this disclosure may
be mechano-
chemically recyclable using high-shear low-temperature mixing process(es) as
disclosed in
US 10,882,951. It has been found that incorporation of fabrics (e.g., a cotton
upper or a
cellulosic backing fabric for a leather-like material) does not inhibit the
mechano-chemical
recycleability as such fabrics are dispersed into the resultant mixed product
and act as fibrous
reinforcement to the compound. Therefore, an illustrative embodiment of a
footwear article
contemplated by this disclosure may include two or more instances of materials
types (e.g., a
foam and an outsole, or a foam/outsole unit and an ENR-based material upper
(fabric-backed
or not), or a foam and an outsole with a fabric upper, etc.), wherein such
materials may be co-
molded, or alternatively bonded with an adhesive from same family of
thermosetting
polymers. The mechano-chemically recyclable attribute of the ENR-based
material curative
or resin-based adhesive (as discussed herein) may enable the entire footwear
article to be
subject to the same mechano-chemical recycling treatment without requiring
separation of the
constituent components.
In one illustrative embodiment of an article configured according to the
present disclosure the
article may be configured as a slide sandal having the above-referenced
combination of
materials. In this embodiment, three constituent components may include an
outsole, a foam,
and an ENR-based material strap. The outsole may be molded in a compression
mold as is
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commonly practiced in the art. The outsole may be comprised of an ENR-based
compound
that is cured with curative formulated according to US 10,400,061. A strap
also made from an
ENR-based compound that is cured with curative formulated according to US
10,400,061
may be provided. The strap may optionally be fabric backed, made by co-molding
a fabric
backer with an ENR-based compound that is cured with curative formulated
according to US
10,400,061. Said strap may in one illustrative embodiment be adhesively bonded
between the
outsole and a foam footbed. In one embodiment, after molding the outsole, it
may be coated
on the backside with an adhesive as disclosed herein. In one embodiment, an
uncured foam
preform may be placed on pre-molded and adhesive-coated outsole, a heated
weight placed
thereon may provide sufficient pressure (-0.5 ¨ 4psi) to cause vulcanization
between the
outsole and the foam and yet still allow the foam preform to concurrently
"rise" (that is,
actually grow in thickness and thereby become a less-dense foam) and cure
(i.e. vulcanize).
In one illustrative embodiment a preferred curing and foaming temperature may
be between
110 C - 170 C, or even more preferably between 120 C - 160 C, for between 10 -
90
minutes, or even more preferably between 15 - 60 minutes. In such a method,
the shape of the
top heated weight may determine the final shape and contour of the footbed
while controlling
the growth of the foam. A slide sandal made according to this embodiment may
consist of
three variations of the same material family (four if the adhesive is
included), which yields an
article that may be subject to mechano-chemical recycling at the end of its
life. Alternatively,
according to this illustrative embodiment, the slide sandal is comprised of
non-
petrochemically derived materials and thus may be returned to the ground for
biodegradation.
Referring now to FIGS. 23A-23D, which provide schematic representations of
four steps for
an illustrative method of making one type of article, the illustrative article
therein may be
configured as a slide sandal. Generally, in a first step as shown in FIG. 23A,
a compression
mold technique may be used to create a pair of outsoles, wherein the
compression molding
process may be completed at a specific temperature(s), pressure(s), and/or
ranges thereof A
sole preform 401a may be positioned in a mold 400 at a specific temperature
and pressure for
a specific amount of time to create a sole (or outsole) 401b. In a second step
as shown in FIG.
23B an adhesive material 403 may be applied to one surface of the outsole(s)
401b to affix a
strap 402 to the outsole 401b. A third step is shown in FIG. 23C, wherein an
uncured foam-
in-place layer (foam footbed preform 404a) may be applied over an upward-
facing surface of
the outsole 401b, such that the foam-in-place layer may cover one or more
terminal ends of
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the strap 402. Finally, in a fourth step as shown in FIG. 23D, a metal plate
(which may be
pre-heated) 405 may be positioned on the foam footbed preform 404a to
facilitate the
foaming process and/or to generate crosslinking of the material to create a
foaming/foamed
footbed 404b, and the article may be placed in an oven for curing.
In an illustrative embodiment of an article configured as a clog-like shoe
(colloquially
referred to oftentimes by the trademark Crocs0), an outsole/sole 401b may in a
first step be
pre-molded using an ENR-50 based compound and cured with curative formulated
according
to US 10,400,061. That outsole/sole 401b may optionally be coated with
adhesive material
403 as disclosed herein on the backside of the outsole/sole 401b. That
adhesive material 403-
coated outsole/sole 401b may be placed in a rubber injection-molding tool that
is fabricated
to form the entire body of the clog-like shoe. In this illustrative
embodiment, a foaming
compound may be injected into the heated mold and the combination of heat from
the tooling
and heat generated by shear (during injection) may result in vulcanization and
foaming of the
compound and concurrent curing of the adhesive-coated outsole to the foamed
shoe body. It
may be preferred to avoid the use of any petrochemical blowing agents to
create the
thermoset foam and instead rely on moisture in compounded ingredients that
turn to steam
during the molding and curing process. Lignocellulosic fillers and starches
are two classes of
illustrative fillers that may carry controlled levels of moisture that may
generate steam during
molding and curing that gives rise to foams. This technology (steam expanded
starch) is
known in the food industry (e.g. to make "corn puffs") but has not been used
as a formulation
approach in thermoset elastomers to create foams.
Referring now to FIGS. 23A-23D, which provide schematic representations of
four steps of
another illustrative method of making one type of article, the illustrative
article therein may
be configured as an injection-molded clog or Croc0-type shoe. Generally, in a
first step as
shown in FIG. 24A, a compression mold technique may be used to create a pair
of outsole(s)
or soles 401b from one or more sole preforms 401a using a mold 400, wherein
the
compression molding process may be completed at a specific temperature(s),
pressure(s),
and/or ranges thereof In a second step as shown in FIG. 24B an adhesive
material 403 may
be applied to one surface of the outsole(s)/soles 401b. A third step is shown
in FIG. 24C,
wherein the outsole(s)/soles 401b with adhesive material 403 applied thereto
may be
positioned within an injection molding tool or foaming compound mold 406.
Finally, in a
fourth step as shown in FIG. 24D a foaming compound may be injected into the
foaming
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compound mold 406 through an injection port 406a using an injection barrel 407
for injection
molding thereof adjacent the adhesive material 403 on the outsole(s)/sole(s)
401b.
In yet another illustrative embodiment of an article according to the present
disclosure that
may be configured as footwear, a shoe may be manufactured using multiple
material types
from the same family. Such an illustrative embodiment may be configured with
an upper
using a leather-like material, an outsole, and a midsole. In this illustrative
embodiment, a pre-
molded outsole may be made using an ENR-50 based compound and cured with
curative
formulated according to US 10,400,061. That outsole/sole 401b may optionally
be coated
with adhesive material 403 as disclosed herein on the backside of the outsole.
A mold 406
may be provided that contains the outsole/sole 401b and also has a heated last
408 around
which is wrapped the pre-manufactured and/or preformed upper 409 (which may be
configured to not entirely envelop the last 408, but only in-part). The last
408 may form one
half of the mold cavity (within the shoe) and the outsole/sole 401b (and the
side of the tool
that holds it) may form the other half of the mold cavity. The pre-
manufactured/preformed
upper 409 may be pinched between the last 408 and the outsole half of the mold
cavity, thus
creating a cavity into which a foaming compound may be injected. The foaming
compound
may be injected through the outsole half of the mold or directly through the
last side of the
tool to fill the space between the pre-molded outsole/sole 401b and the last
408; while
entrapping and bonding to the upper 409 that is wrapped around the last 408
(at least in-part).
In this manufacturing process, the foaming compound may serve as the midsole
(and/or
insole) and subsequently may initiate bonding to and between the outsole/sole
401b and
upper 409.
Referring now to FIGS. 25A-25F, which provide schematic representations of six
steps of
another illustrative method of making one type of article, the illustrative
article therein may
be configured as a shoe having a distinct sole and upper portion. Generally,
in a first step as
shown in FIG. 25A, a compression mold technique may be used to create a pair
of
outsole(s)/soles 401b, wherein the compression molding process may be
completed at a
specific temperature(s), pressure(s), and/or ranges thereof In a second step
as shown in FIG.
25B an adhesive material 403 may be applied to one surface of the
outsole(s)/sole(s) 401b.
Additionally, a foam injection aperture 401c may be fashioned in a portion of
each
outsole/sole 401b if not done in step one. A third step is shown in FIG. 25C,
wherein a
portion of a shoe preformed upper 409 portion may be wrapped around a portion
of the
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outsole(s)/sole(s) 401b.
In a fourth step as shown in FIG. 25D, the upper 409 portion of the shoe and
outsole/sole
401b may be inverted for positioning in a mold 406, which may be configured as
a foaming
compound mold 406. In a fifth step shown in FIG. 25E, the outsole/sole 401b
and upper 409
may be positioned with respect to a mold 406. Finally, FIG. 25F shows a sixth
step wherein a
midsole compound (which may be configured as a foaming compound and/or foaming
material as disclosed in detail herein without limitation unless otherwise
indicated in the
following claims) may be injected into the foam injection aperture 401c formed
in the
outsole/sole 401b. However, the preceding examples of illustrative methods of
manufacture
for an article configured as a shoe are in no way limiting to the scope of the
present
disclosure unless otherwise indicated in the following claims
These three illustrative embodiments of articles and method for making same
are neither
exhaustive nor exclusive but are meant to serve as examples of the types of
construction that
may be utilized to combine multiple material types wherein all the material
types are of the
same broad material family, and the present disclosure is not limited to
articles configured as
footwear unless otherwise indicated in the following claims. The common cure
system,
relying on a reaction between a carboxylic acid and an epoxide to facilitate
crosslinking with
B-hydroxyester linkages, may enable co-mingling and bonding of the various
form factors of
the material - whether it be an elastomeric outsole compound, an adhesive
layer, a leather-
like sheet good, a rigid or semi-rigid and/or plastic-like material, and/or a
foam. Textiles may
be incorporated without limitation into the construction of such a shoe unless
otherwise
indicated in the following claims.
VI. Method of recycling
Illustrative embodiments of articles made according to the present disclosure
that are
configured as footwear articles may contain polymers that are thermosets
manufactured with
similar cure (vulcanization) chemistry. The particular cure chemistry,
described in detail in
US 10,400,061, is unique in its ability to make elastomers that may be mechano-
chemically
recycled according to US 10,882,951. This method of recycling may utilize a
very high
specific power input while simultaneously limiting the heating of the
material.
The recycling of articles (which may be configured as footwear) that utilizes
materials
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disclosed herein may be subject to mechano-chemical recycling without
requiring any
pretreatment apart from the removal of metallic hardware that may have been
added to the
article (as to not damage the processing equipment) so as to create a metallic-
free mixture. In
one illustrative embodiment, the mechano-chemical recycling may be conducted
in two
stages. In the first stage, articles (e.g., footwear) to be recycled may be
fed into an internal
rubber mixer. The rubber mixer may be used to break down the articles (e.g.,
footwear) and
make a homogeneous mixture - in practice, the mixer may not be able to deliver
the specific
energy required to render the mixture a millable gum (due to the clearance
limitations in a
rubber mixer and the heat build-up therein), but it is capable of making a
rubber fluff, an
illustrative embodiment of which is depicted in FIG. 22.
In a second stage, this fluff may be fed to a two-roll rubber mill with a nip
set to 0.2mm-
2.0mm, or more preferably to 0.4mm - 1.6mm. The mill must be set with a
friction ratio of
1.1 - 1.5 or even more preferably between 1.2 - 1.4 to create the energy input
requirements to
create a millable gum. However, other values for these clearances may be used
in other
embodiments without limitation unless otherwise indicated in the following
claims. A two-
roll rubber mill allows for the combination of sufficient cooling (to prevent
scorch, i.e., re-
curing) and the specific energy required. After the mixture is rendered a
millable gum
compound, it may be molded again into a new article; either a component of
footwear or
another article appropriate to the properties of the material (now a mixture
of various inputs
which may include ground-up textiles that were part of the recycled article
(e.g., footwear)).
In another illustrative embodiment, the recycling may be conducted in a single
stage wherein
the article (e.g., footwear) may be delivered directly to a two-roll mill and
the entire
shredding, blending, and creating of a millable gum compound are all achieved
in one step.
VII. Example articles
In this disclosure, particular focus has been placed on footwear, but there
are analogous
articles that are combinations of elastomeric solids/molded components,
elastomeric foams,
rigid or semi-rigid plastic-like materials, adhesives, coatings, and/or
flexible sheet goods
(e.g., leatherlike materials and/or textiles) that may also be manufactured
and/or recycled
according to the methods disclosed herein. For example, a handbag with
elastomeric corner
protectors, sheet good sides, and a foam bottom may, by analogy, be
manufactured and/or
recycled according to the methods disclosed herein. Accordingly, the present
disclosure may
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be applicable to bags of nearly any kind, including but not limited to purses,
clutches,
satchels, messenger bags, pouches, backpacks, knapsacks, and/or similar
bags/sacks without
limitation unless otherwise indicated in the following claims. A computer
backpack or bag
may also be manufactured using a combination of elastomeric solid corner
protectors and
handles, sheet good sides, and foam bumpers to protect electronics; such an
article may be
manufactured and/or recycled according to the methods disclosed herein, as may
any other
suitable article without limitation unless otherwise indicated in the
following claims.
Additional articles may be manufactured utilizing various combinations of the
six materials
having a common chemistry of B-hydroxyester linkages, wherein such articles
include but are
not limited to furniture and its components (e.g., coverings, cushions,
structural members,
etc.), luggage and its components (e.g., exterior coverings, cushions,
bumpers, handles,
clasps, buckles, zippers, etc.), electronics cases and/or accessories (e.g.,
mobile phone, tablet,
and/or mobile computer cases and/or covers), and/or similar articles without
limitation unless
otherwise indicated in the following claims.
Also, by analogy, such articles that are combinations of materials from the
same material
family, using the same cure system, but be manifest in different material
forms - any such
article - may be recycled by the mechano-chemical method. The mixture of those
input
materials may likewise be rendered into a millable gum compound and thus be
moldable into
a new article without limitation unless otherwise indicated in the following
claims.
Although the methods described and disclosed herein may be configured to
utilize a curative
comprised of a natural materials, the scope of the present disclosure, any
discrete process step
and/or parameters therefor, and/or any apparatus for use therewith is not so
limited and
extends to any beneficial and/or advantageous use thereof without limitation
unless so
indicated in the following claims.
The materials used to construct the apparatuses and/or components thereof for
a specific
process will vary depending on the specific application thereof, but it is
contemplated that
polymers, natural materials, and/or combinations thereof may be especially
useful in some
applications. Accordingly, the above-referenced elements may be constructed of
any material
known to those skilled in the art or later developed, which material is
appropriate for the
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specific application of the present disclosure without departing from the
spirit and scope of
the present disclosure unless so indicated in the following claims.
Having described preferred aspects of the various processes, apparatuses, and
products made
thereby, other features of the present disclosure will undoubtedly occur to
those versed in the
art, as will numerous modifications and alterations in the embodiments and/or
aspects as
illustrated herein, all of which may be achieved without departing from the
spirit and scope of
the present disclosure. Accordingly, the methods and embodiments pictured and
described
herein are for illustrative purposes only, and the scope of the present
disclosure extends to all
processes, apparatuses, and/or structures for providing the various benefits
and/or features of
the present disclosure unless so indicated in the following claims.
While the chemical process, process steps, components thereof, apparatuses
therefor,
products made thereby, and impregnated substrates according to the present
disclosure have
been described in connection with preferred aspects and specific examples, it
is not intended
that the scope be limited to the particular embodiments and/or aspects set
forth, as the
embodiments and/or aspects herein are intended in all respects to be
illustrative rather than
restrictive. Accordingly, the processes and embodiments pictured and described
herein are no
way limiting to the scope of the present disclosure unless so stated in the
following claims.
Although several figures are drawn to accurate scale, any dimensions provided
herein are for
illustrative purposes only and in no way limit the scope of the present
disclosure unless so
indicated in the following claims. It should be noted that the welding
processes, apparatuses
and/or equipment therefor, and/or impregnated and reacted upon substrates
produced thereby
are not limited to the specific embodiments pictured and described herein, but
rather the
scope of the inventive features according to the present disclosure is defined
by the claims
herein. Modifications and alterations from the described embodiments will
occur to those
skilled in the art without departure from the spirit and scope of the present
disclosure.
Any of the various features, components, functionalities, advantages, aspects,
configurations,
process steps, process parameters, etc. of a chemical process, a process step,
a substrate,
and/or a impregnated and reacted substrate, may be used alone or in
combination with one
another depending on the compatibility of the features, components,
functionalities,
advantages, aspects, configurations, process steps, process parameters, etc.
Accordingly, an
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infinite number of variations of the present disclosure exist. Modifications
and/or
substitutions of one feature, component, functionality, aspect, configuration,
process step,
process parameter, etc. for another in no way limit the scope of the present
disclosure unless
so indicated in the following claims.
It is understood that the present disclosure extends to all alternative
combinations of one or
more of the individual features mentioned, evident from the text and/or
drawings, and/or
inherently disclosed. All of these different combinations constitute various
alternative aspects
of the present disclosure and/or components thereof The embodiments described
herein
explain the best modes known for practicing the apparatuses, methods, and/or
components
disclosed herein and will enable others skilled in the art to utilize the
same. The claims are to
be construed to include alternative embodiments to the extent permitted by the
prior art.
Unless otherwise expressly stated in the claims, it is in no way intended that
any process or
method set forth herein be construed as requiring that its steps be performed
in a specific
order. Accordingly, where a method claim does not actually recite an order to
be followed by
its steps or it is not otherwise specifically stated in the claims or
descriptions that the steps are
to be limited to a specific order, it is no way intended that an order be
inferred, in any respect.
This holds for any possible non-express basis for interpretation, including
but not limited to:
matters of logic with respect to arrangement of steps or operational flow;
plain meaning
derived from grammatical organization or punctuation; the number or type of
embodiments
described in the specification.
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