Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BICOMPONENT F1BERS COMPRISING A THERMOPLASTIC POLYMER SURROUNDING
A STARCH RICH CORE
FIELD OF THE INVENTION
The present invention relates to multicomponent fibers comprising a
thermoplastic
polymer surrounding and protecting a starch rich core. The fibers can be used
to make nonwoven
webs and disposable articles.
BACKGROUND OF THE INVENTION
There has not been much success at making starch containing fibers on a high
speed,
industrial level due to many factors. Because of the costs, the difficulty in
processing, and end-
use properties there has been little or no commercial success. Starch fibers
are much more
difficult to produce than films, blow-molded articles, and injection-molded
articles containing
starch. This is because of the short processing time required for starch
processing due to rapid
crystallization or other structure formation characteristics of starch. . The
local strain rate and
shear rate is much greater in fiber production than other processes.
Additionally, a homogeneous
composition is required for fiber spinning. For spinning fine fibers, small
defects, slight
inconsistencies, or non-homogeneity in the melt are not acceptable for a
commercially viable
process. Therefore, the selection of materials, configuration of the fibers,
and processing
conditions are critical. In addition to the difficulty during processing, the
end-use properties are
not suitable for many commercial applications. This is because the starch
fibers typically have
low tensile strength, are sticky, and are not well suited for fiber-to-fiber
bonding in nonwoven
webs or substrates.
To produce fibers that have more acceptable processability and end-use
properties, it is
desirable to use non-starch, thermoplastic polymers in combination with
starch. The melting
temperature of the thermoplastic polymer should be high enough for end-use
stability, to prevent
melting or undue structural deformation during use, but low enough so that the
starch/thermoplastic fibers can are processable without burning the starch.
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There exists today an unmet need for cost-effective, easily processable, and
functional
starch-containing fibers. The present invention can provide bicomponent fibers
that are cost-
effective, easily processable, and highly functional. The fibers are made of a
starch rich
component which is completely surrounded by a thermoplastic polymer component.
The starch
and polymer bicomponent fiber is suitable for use in commercially available
equipment for
making bicomponent fibers. There is also a need for disposable, nonwoven
articles made from
these fibers. The present invention provides such disposable, nonwoven
articles made from
starch-containing bicomponent fibers.
SUMMARY OF THE INVENTION
The present invention is directed to bicomponent fibers. The bicomponent
fibers will
comprise one component comprising thermoplastic starch which is completely
surrounded by and
protected by another component comprising a thermoplastic polymer. The
configuration of the
bicomponent fibers can be sheath-core including, for example, sheath-core with
a single core
surrounded by the sheath, or a plurality of two or more cores surrounded by a
sheath, referred to
herein as an islands-in-the-sea configuration.
The thermoplastic polymer protects the starch component. This is particularly
relevant
during end-use where the starch component alone may not tolerate the
environmental conditions
without significant loss in fiber properties. The protection may be
mechanical, thermodynamic,
electrical, solvent based, or combinations thereof. The protection of the
starch component also
makes the fibers more functional as the fibers are more temperature stable,
more resistant to
solvents, and able to be thermally bonded.
The present invention is also directed to nonwoven webs and disposable
articles
comprising the bicomponent fibers. The nonwoven webs may also contain other
synthetic or
natural fibers blended with the fibers of the present invention. The nonwoven
webs may also
contain other synthetic or natural fibers blended with the fibers of the
present invention.
Optional fibers include, but are not limited to, fibers comprising cellulosic
pulp, regenerated
cellulose, polypropylene, polyethylene terephthalate, and nylon, their various
polymers and
combinations thereof
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present invention
will become
better understood with regard to the following description, appended claims,
and accompanying
drawings where:
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Figure 1, including Figures lA through lE, illustrate a cross-sectional views
of
bicomponent fibers having a sheath/core configuration.
Figure 2, including Figures 2A through 2B, illustrate a cross-sectional view
of
bicomponent fibers having an islands-in-the-sea configuration.
DETAILED DESCRIPTION OF THE INVENTION
All percentages, ratios and proportions used herein are by weight percent of
the
composition, unless otherwise specified. All average values are calculated "by
weight" of the
composition or components thereof, unless otherwise expressly indicated.
"Average molecular
weight", or "molecular weight" for polymers, unless otherwise indicated,
refers to number
average molecular weight. Number average molecular weight, unless otherwise
specified, is
determined by gel permeation chromatography. All patents or other publications
cited herein are
incorporated herein by reference with respect to all text contained therein
for the purposes for
which the reference was cited. Inclusion of any such patents or publications
is not intended to be
an admission that the cited reference is citable as prior art or that the
subject matter therein is
material prior art against the present invention. The compositions, products,
and processes
described herein may comprise, consist essentially of, or consist of any or
all of the required
and/or optional components, ingredients, compositions, or steps described
herein.
The specification contains a detailed description of (1) materials of the
present invention,
(2) configuration of the bicomponent fibers, (3) material properties of the
bicomponent fibers, (4)
processes, and (5) articles.
(1) Materials
Component A: Thermoplastic Polymers
Suitable melting temperatures of the thermoplastic polymers, as well as the
thermoplastic
polymer component, are from about 60°C to about 300°C,
preferably from about 80°C to about
250°C and preferably from 100°C-215°C. Thermoplastic
polymers having a melting temperature
(Tm) above 250°C may be used if plasticizers or diluents or other
polymers are used to lower the
observed melting temperature, such that the melting temperature of the
composition of the
thermoplastic polymer-containing component is within the above ranges. It may
be desired to use
a thermoplastic polymer having a glass transition (Tg) temperature of less
than 0°C. The
thermoplastic polymer component has rheological characteristics suitable for
melt spinning. The
molecular weight of the polymer should be sufficiently high to enable
entanglement between
polymer molecules and yet low enough to be melt spinnable. For melt spinning,
suitable
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thermoplastic polymers can have molecular weights about 1,000,000 g/mol or
below, preferably
from about 5,000 g/mol to about 800,000 g/mol, more preferable from about
10,000 g/mol to
about 700,000 g/mol and most preferably from about 20,000 g/mol to about
500,000 g/mol
The thermoplastic polymers desirably should be able to solidify fairly
rapidly, preferably
under extensional flow, as typically encountered in known processes as staple
fibers (spin draw
process) or spunbond/meltblown continuous filament process, and desirably can
form a thermally
stable fiber structure. "Thermally stable fiber structure" as used herein is
defined as not
exhibiting significant melting or dimensional change at 25°C and
ambient atmospheric pressure
over a period of 24 hours at 50% relative humidity when diameter is measured
and the fibers are
placed in the environment within five minutes of their formation. Dimensional
changes in
measured fiber diameter greater than 25% difference, using as a basis the
corresponding, original
fiber diameter measurement, would be considered significant. If the original
fiber is not round,
the shortest diameter should be used for the calculation. The shortest
diameter should also be
used for the 24 hour measurement also.
Suitable thermoplastic polymers include polyolefms such as polyethylene or
copolymers
thereof, including low, high, linear low, or ultra low density polyethylenes,
polypropylene or
copolymers thereof, including atactic polypropylene; polybutylene or
copolymers thereof;
polyamides or copolymers thereof, such as Nylon 6, Nylon 11, Nylon 12, Nylon
46, Nylon 66;
polyesters or copolymers thereof, such as polyethylene terephthalate; olefin
carboxylic acid
copolymers such as ethylene/acrylic acid copolymer, ethylene/maleic acid
copolymer,
ethylene/methacrylic acid copolymer, ethylene/vinyl acetate copolymers or
combinations thereof;
polyacrylates, polymethacrylates, and their copolymers such as poly(methyl
methacrylates).
Other nonlimiting examples of polymers include polycarbonates, polyvinyl
acetates,
poly(oxymethylene), styrene copolymers, polyacrylates, polymethacrylates,
poly(methyl
methacrylates), polystyrene/methyl methacrylate copolymers, polyetherimides,
polysulfones, or
combinations thereof. In some embodiments, thermoplastic polymers include
polypropylene,
polyethylene, polyamides, polyvinyl alcohol, ethylene acrylic acid, polyole~n
carboxylic acid
copolymers, polyesters, and combinations thereof.
Biodegradable thermoplastic polymers are also suitable for use herein.
Biodegradable
materials are susceptible to being assimilated by microorganisms such as
molds, fungi, and
bacteria when the biodegradable material is buried in the ground or otherwise
comes in contact
with the microorganisms including contact under environmental conditions
conducive to the
growth of the microorganisms. Suitable biodegradable polymers also include
those
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biodegradable materials which are environmentally degradable using aerobic or
anaerobic
digestion procedures, or by virtue of being exposed to environmental elements
such as sunlight,
rain, moisture, wind, temperature, and the lilce. The biodegradable
thermoplastic polymers can be
used individually or as a combination of biodegradable or non-biodegradable
polymers.
Biodegradable polymers include polyesters containing aliphatic components.
Among the
polyesters are ester polycondensates containing aliphatic constituents and
poly(hydroxycarboxylic) acid. The ester polycondensates include diacids/diol
aliphatic
polyesters such as polybutylene succinate, polybutylene succinate co-adipate,
aliphaticlaromatic
polyesters such as terpolymers made of butylenes diol, adipic acid and
terephthalic acid. The
poly(hydroxycarboxylic) acids include lactic acid based homopolymers and
copolymers,
polyhydroxybutyrate (PHB), or other polyhydroxyalkanoate homopolymers and
copolymers.
Such polyhydroxyalkanoates include copolymers of PHB with higher chain length
monomers,
such as C6 - C12, and higher, polyhydroxyalkanaotes, such as disclosed in US
Patent RE 36,548
and US Patent 5,990,271.
An example of a suitable commercially available poly lactic acid is
NATUREWORI~S
from Cargill Dow and LACEA from Mitsui Chemical. An example of a suitable
commercially
available diacid/diol aliphatic polyester is the polybutylene
succinate/adipate copolymers sold as
BIONOLLE 1000 and BIONOLLE 3000 from the Showa High Polymer Company, Ltd.
Located
in Tokyo, Japan. An example of a suitable commercially available
aliphatic/aromatic copolyester
is the poly(tetramethylene adipate-co-terephthalate) sold as EASTAR BIO
Copolyester from
Eastman Chemical or ECOFLEX from BASF.
The selection of the polymer and amount of polymer will effect the softness,
texture, and
properties of the final product as will be understood by those or ordinary
skill in the art. The
thermoplastic polymer component can contain a single polymer species or a
blend of two or more
non-starch thermoplastic polymers. Additionally, other materials, including
but not limited to
thermoplastic starch, can be present in the thermoplastic polymer component.
Typically, non-
starch, thermoplastic polymers are present in an amount of from about 51% to
100%, preferably
from about 60% to about 95%, more preferably from about 70% to about 90%, by
total weight of
the thermoplastic polymer component.
The thermoplastic polymer component surrounds and can protect the starch
component
from ambient conditions which can include, but are not limited to, mechanical,
thermodynamic,
electrical, or solvent conditions, or combinations thereof. The thermoplastic
polymer component
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can also makes the fibers more functional as the fibers are more temperature
stable, more
resistant to solvents, and able to be thermally bonded.
Component B: Thermoplastic Starch
The present invention relates to the use of starch, a low cost naturally
occurring
biopolymer. The starch used in the present invention is thermoplastic,
destructured starch. The
term "destructurized starch" is used to mean starch that is no longer in its
naturally occurring
granular structure. The term "thermoplastic starch" or "TPS" is used to mean
starch with a
plasticizes for improving its thermoplastic flow properties so that it may be
able to be spun into
fibers. Natural starch does not melt or flow like conventional thernloplastic
polymers. Since
natural starch generally has a granular structure, it desirably should be
"destructurized", or
"destructured", before it can be melt processed and spun like a thermoplastic
material. Without
intending to be bound by theory, the granular structure of starch is
characterized by granules
comprising a structure of discrete amylopectin and amylose regions in a starch
granule. This
granular structure is broken down during destructurization, which can be
followed by a volume
expansion of the starch component in he presence of the solvent or
plasticizes. Starch undergoing
destructuring in the presence of the solvent or plasticizes also typically has
an increase in
viscosity versus non-destructured starch with the solvent or plasticizes. The
resulting
destructurized starch can be in gelatinized form or, upon drying and or
annealing, in crystalline
form. However once broken down the natural granular stl-ucture of starch will
not, in general,
return. It is desirable that the starch be fully destructured such that no
lumps impacting the fiber
spinning process are present. The destructuring agent used to destructure the
starch may remain
with the starch during further processing, or may be transient, in that it is
removed such that it
does not remain in the fiber spun with the starch.
Starch can be destructured in a variety of different ways. The starch can be
destructurized with a solvent. For example, starch can be destructurized by
subjecting a mixture
of the starch and solvent to heat, which can be under pressurized conditions
and shear, to
gelatinize the starch, leading to destructurization. Solvents can also act as
plasticizers and may be
desirably retained in the composition to perform as a plasticizes during later
processing. A variety
of plasticizing agents that can act as solvents to destructure starch are
described herein. These
include the low molecular weight or monomeric plasticizers, such as but not
limited to hydroxyl-
containing plasticizers, including but not limited to the polyols, e.g.
polyols such as mannitol,
sorbitol, and glycerin. Water also can act as a solvent and plasticizes for
starch.
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For starch to flow and be melt spinnable like a conventional thermoplastic
polymer, it
should have plasticizer present. If the destructuring agent is removed, it is
the nature of the starch
to in general remain destructured, however a plasticizer should be added to or
otherwise included
in the starch component to impart thermoplastic properties to the starch
component in order to
facilitate fiber spinning. Thus, the plasticizer present during spinning may
be the same one used
to destructure the starch. Alternately, especially when the destructuring
agent is transient as
described above (for example water), a separate or additional plasticizer may
be added to the
starch. Such additional plasticizer can be added prior to, during, or after
the starch is
destructured, as long as it remains in the starch for the fiber spinning step.
Suitable naturally occurring starches can include, but are not limited to,
corn starch
(including, for example, waxy maize starch), potato starch, sweet potato
starch, wheat starch,
sago palm starch, tapioca starch, rice starch, soybean starch, arrow root
starch, bracken starch,
lotus starch, cassava starch, high amylose corn starch, and commercial amylose
powder. Blends
of starch may also be used. Though all starches are useful herein, the present
invention is most
commonly practiced with natural starches derived from agricultural sources,
which offer the
advantages of being abundant in supply, easily replenishable and inexpensive
in price. Naturally
occurring starches, particularly corn starch (including, for example, waxy
maize starch), and
wheat starch, are starch polymers of choice due to their economy and
availability. Modified
starch may also be used. Modified starch is defined as non-substituted, or
substituted, starch that
has had its native molecular weight characteristics changed (i.e, the
molecular weight is changed
but no other changes are necessarily made to the starch). Molecular weight can
be modified,
preferably reduced, by any technique numerous of which are well known in the
art. These
include, for example, chemical modifications of starch by, for example, acid
or alkali hydrolysis,
acid reduction, oxidative reduction, enzymatic reduction, physical/mechanical
degradation (e.g.,
via the thermomechanical energy input of the processing equipment), or
combinations thereof.
The thermomechanical method and the oxidation method offer an additional
advantage when
carried out in situ. The exact chemical nature of the starch and molecular
weight reduction
method is not critical as long as the average molecular weight is provided at
the desired level or
range. Such techniques can also reduce molecular weight distribution.
Natural, unmodified starch generally has a very high average molecular weight
and a
broad molecular weight distribution (e.g. natural corn starch has an average
molecular weight of
up to about 60,000,000 grams/mole (g/mol)). It is desirable to reduce the
molecular weight of the
starch for use in the present invention. Molecular weight reduction can be
obtained by any
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technique known in the art, including those discussed above. Ranges of
molecular weight for
destructured starch or starch blends added to the melt can be from about 3,000
g/mol to about
8,000,000 g/mol, preferably from about 10,000 g/mol to about 5,000,000 g/mol,
and more
preferably from about 20,000 g/mol to about 3,000,000 glmol.
Optionally, substituted starch can be used. Chemical modifications of starch
to provide
substituted starch include, but are not limited to, etherification and
esterification. For example,
methyl, ethyl, or propyl (or larger aliphatic groups) can be substituted onto
the starch using
conventional etherification and esterification techniques as well known in the
art. Such
substitution can be done when the starch is in natural, granular form or after
it has been
destructured. It will be appreciated that substitution can reduce the rate of
biodegradability of the
starch, but can also reduce the time, temperature, shear, and/or pressure
conditions for
destructurization. The degree of substitution of the chemically substituted
starch is typically, but
not necessarily, from about 0.01 to about 3.0, and can also be from about 0.41
to about 0.06.
Typically, the thermoplastic starch comprises from about 51 % to about 100%,
preferably from about 60% to about 95%, more preferably from about 70% to
about 90°!° by
weight of the thermoplastic starch component. The ratio of the starch
component to the
thermoplastic polymer will determine the percent of thermoplastic starch in
the bicomponent
fiber component. The weight of starch in the composition includes starch and
its naturally
occurring bound water content. The term "bound water" means the water found
naturally
occurring in starch and before mixing of starch with other components to make
the composition
of the present invention. The term "free water" means the water that is added
in making the
composition of the present invention. A person of ordinary skill in the art
would recognize that
once the components are mixed in a composition, water can no longer be
distinguished by its
origin. Natural starch typically has a bound water content of about S% to
about 16% by weight
of starch.
Plasticizes
One or more plasticizers can be used in the present invention to destructurize
the starch
and enable the starch to flow, i.e. create a thermoplastic starch. As
discussed above, a plasticizes
may be used as a destructuring agent for the starch. That plasticizes may
remain in the
destructured starch component to function as a plasticizes for the
thermoplastic starch, or may be
removed and substituted with a different plasticizes in the thermoplastic
starch component. The
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plasticizers may also improve the flexibility of the final products, which is
believed to be due to
the lowering of the glass transition temperature of the composition. A
plasticizes or diluent for
the thermoplastic polymer component may be present to lower the polymer's
melting
temperature, modify flexibility of the final product, or improve overall
compatibility with the
thermoplastic starch blend. Furthermore, thermoplastic polymers with higher
melting
temperatures may be used if plasticizers or diluents are present which
suppress the melting
temperature of the polymer.
In general, the plasticizers should be substantially compatible with the
polymeric
components of the present invention with which they are intermixed. As used
herein, the teen
"substantially compatible" means when heated to a temperature above the
softening and/or the
melting temperature of the composition, the plasticizes is capable of forming
a homogeneous
mixture with polymer present in the component in which it is intermixed. One
way to ensure
substantial compatability is to enzyrnatically or synthetically graft or react
groups onto starch or
starch onto a polymer.
The plasticizers herein can include monomeric compounds and polymers. The
polymeric plasticizers will typically have a molecular weight of about 100,000
g/mol or less.
Polymeric plasticizers can include block copolymers and random copolymers,
including
terpolymers thereof. In certain embodiments, the plasticizes has a low
molecular weight
plasticizes, for example a molecular weight of about 20,000 g/mol or less, or
about 5,000 g/mol
or less, or about 1,000 g/mol or less. The plasticizers may be used alone or
more than one
plasticizes may be used in any particular component of the present invention.
Also useful plasticizers are hydroxy-based polymers such as polyvinyl alcohol,
ethylene
vinyl alcohol, copolymers and blends thereof at various substitution levels.
The plasticizes can be, for example, an organic compound having at least one
hydroxyl
group, including polyols having two or more hydroxyls. Nonlimiting examples of
useful hydroxyl
plasticizers include sugars such as glucose, sucrose, fructose, raffinose,
maltodextrose, galactose,
xylose, maltose, lactose, mannose erythrose, and pentaerythritol; sugar
alcohols such as
erythritol, xylitol, malitol, mannitol and sorbitol; polyols such as glycerol
(glycerin), ethylene
glycol, propylene glycol, dipropylene glycol, butylene glycol, hexane triol,
and the like, and
polymers thereof; and mixtures thereof. Suitable plasticizers especially
include glycerine,
mannitol, and sorbitol.
Also useful herein hydroxyl polymeric plasticizers such as poloxomers
(polyoxyethylene
/polyoxypropylene block copolymers) and poloxamines
(polyoxyethylene/polyoxypropylene
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blocle copolymers of ethylene diamine). These copolymers are available as
Pluronic~ from
BASF Corp., Parsippany, NJ. Suitable poloxamers and poloxamines are available
as
Synperonic~ from ICI Chemicals, Wilmington, DE, or as Tetronic~ from BASF
Corp.,
Parsippany, NJ.
Also suitable for use herein are hydrogen bond forming organic compounds,
including
those which do not have hydroxyl group, including urea and urea derivatives;
anhydrides of sugar
alcohols such as sorbitan; animal proteins such as gelatin; vegetable proteins
such as sunflower
protein, soybean proteins, cotton seed proteins; and mixtures thereof. Other
suitable plasticizers
are phthalate esters, dimethyl and diethylsuccinate and related esters,
glycerol triacetate, glycerol
mono and diacetates, glycerol mono, di, and tripropionates, butanoates,
stearates, lactic acid
esters, citric acid esters, adipic acid esters, stearic acid esters, oleic
acid esters, and other father
acid esters which are biodegradable. Aliphatic acids such as ethylene acrylic
acid, ethylene
malefic acid, butadiene acrylic acid, butadiene malefic acid, propylene
acrylic acid, propylene
malefic acid, and other hydrocarbon based acids.
The amount of plasticizes is dependent upon the molecular weight and amount of
starch
and the affinity of the plasticizes for the starch or thermoplastic polymer.
Any amount that
effectively plasticizes the starch component can be used. The plasticizes
should sufficiently
plasticize the starch component so that it can be processed effectively to
form fibers. Generally,
the amount of plasticizes increases with increasing molecular weight of
starch. Typically, the
plasticizes can be present in an amount of from about 2% to about 70%, and can
also be from
about 5% to about 55%, or from about 10% to about 50% of the component into
Which it is
intermixed. Polymeric incorporated into the starch component that function as
plasticizers for the
starch shall be counted as part of the plasticizes constituent of that
component of the present
invention. Plasticizes is optional for the thermoplastic polymer components in
the present
invention, and zero percent or amounts below 2% are not meant to be excluded.
Optional Materials
Optionally, other ingredients may be incorporated into the thermoplastic
starch component
and thermoplastic polymer component. These optional ingredients may be present
in quantities of
less than about 50%, preferably from about 0.1% to about 30%, and more
preferably from about
0.1% to about 10% by weight of the component. The optional materials may be
used to modify the
processability andlor to modify physical properties such as elasticity,
tensile strength and modulus
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of the final product. Other benefits include, but are not limited to,
stability including oxidative
stability, brightness, color, flexibility, resiliency, workability, processing
aids, viscosity modifiers,
and odor control. A preferred processing aid is magnesium stearate. Another
optional material that
may be desixed, particularly in the starch component, is ethylene acrylic
acid, commercially
available as Primacore by Dow Chemical Company. Examples of optional
ingredients are found in
US application serial number 091853,131.
(2) Configuration
The fibers of the present invention are, at least, bicomponent fibers.
Component, as used
herein, is defined as a separate part of the fiber that has a spatial
relationship to another part of
the fiber. The term bicomponent, as used herein, is defined as a fiber having
at least two separate
parts in spatial relationship to one another at the exit from the extrusion
equipment. The
bicomponent fibers hereof may optionally be multicomponent with three or more
components, as
long as at least one component is a thermoplastic polymer component, as
described above,
surrounding at least one thermoplastic, destructured starch component, also
described above.
Accordingly, the term "bicomponent fiber" is not meant to exclude other
multicomponent fibers,
unless otherwise expressly indicated. Thus, the bicomponent or multicomponent
fibers hereof can
have more than two separate components, such as, without limitation,
tricomponent. The
different components of multicomponent fibers are arranged in substantially
distinct regions
across the cross-section of the fiber and extend continuously along the length
of the fiber.
As described above, either or both of the required components may be
multiconstituent
components. Constituent, as used herein, is defined as meaning the chemical
species of matter or
the material. Multiconstituent fiber, as used herein, is defined to mean a
fiber, or component
thereof, containing more than one chemical species or material.
The bicomponent fibers of the present invention may be in any of several
different
configurations as long as the thermoplastic polymer component surrounds the
starch component.
The bicomponent fibers, for example, may be in an islands-in-the-sea
configuration (a plurality of
starch component cores surrounded by a thermoplastic polymer sheath) or a
sheath-core
configuration (a single starch component core surrounded by a thermoplastic
polymer component
sheath) wherein the starch component is encompassed by, or completely
surrounded by, the
thermoplastic polymer.
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Figure 1 includes schematic drawings illustrating a cross-sectional view of a
bicomponent fiber having a sheath/core configuration. Component X is the
starch component as
it is always surrounded by Component Y, the thermoplastic polymer component.
Figure lA illustrates a typical concentric sheath-core confitguration.
Figure 1B illustrate a sheath-core configuration with a solid core and shaped
continuous
sheath.
Figure 1C illustrates a sheath-core configuration with a hollow core and
continuous
sheath.
Figure 1D illustrates a sheath-core configuration with a hollow core and
shaped
continuous sheath.
Figure lE illustrates an eccentric sheath-core configuration.
Figure 2 includes schematic drawings illustrating a cross-sectional view of a
bicomponent fiber having an islands-in-the-sea configuration.
Figure 2A is a solid islands-in the-sea configuration with Component X being
surrounded
by Component Y. Component X is triangular in shape.
Figure 2B is a solid islands-in the-sea configuration with Component X being
surrounded
by Component Y.
Figure 2C is a hollow islands-in the-sea configuration with Component X being
surrounded by Component Y.
The weight ratio of the thermoplastic starch component to thermoplastic
polymer
component can be from about 5:95 to about 95:5. In alternate embodiments, the
ratio is from
about 10:90 to about 65:35 and or from about 15:85 to about 50:50.
(3) Material Properties
The bicomponent fibers of the present invention can have several benefits over
monocomponent starch and polymer blend fibers. Because the thermoplastic
polymer completely
surrounds the starch component, the starch rich component is protected during
end-use. This
enables the bicomponent fiber to be produced having good fiber properties such
as elongation-at-
brealc or tensile, strength. The thermoplastic polymer component can also
provide protection from
mechanical, thermodynamic, electrical, and chemical environmental factors or
conditions, and
combinations thereof. The thermoplastic polymer component also can enable the
fibers to be
bonded to malce nonwoven substrates.
It has also been found that this bicomponent configuration generally males the
fiber more
temperature stable, particularly when Tm of the thermoplastic polymer
component is at least about
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100°C, and especially when at least about 125°C. Improved
temperature stability facilities the
processing of these fibers with various post-fiber formation processes
commonly used in the art
including, but not limited to, thermal bonding of fibers such as but not
limited to formation of
thermally bonded fibrous substrates of webs, post-processing techniques such
as but not limited to
mechanical drawing, and other processes that otherwise may not be suitable for
use with
monocomponent starch-containing fibers. The temperature that the fiber is
stable until depends
upon the specific polymer used, the ratio of thermoplastic polymer to starch
component, and the
specific configuration. The melting temperature of the starch component is
lower than the melting
temperature of the thermoplastic polymer component.
The fibers of the present invention can also have the benefit of being more
resistant to polar
and/or non-polar solvents compared to monocomponent starch-containing fibers.
This enables
starch fibers to be used in various environments, such as aqueous
environments, where typical
starch fibers may not be suitable.
The diameter of the fiber of the present invention is typically less than
about 200
micrometers (microns), and alternate embodiments can be less than about 100
microns, less than
about 50 microns, or less than 30 microns. In one embodiment hereof, the
fibers have a diameter of
from about 5 microns to about 25 microns. Fiber diameter is controlled factors
well known in the
fiber spinning art including, for example, spinning speed and mass through-
put.
The fibers produced in the present invention may be environmentally degradable
depending upon the amount of starch that is present, the polymer used, and the
specific
configuration of the fiber. "Environmentally degradable" is defined as being
biodegradable,
disintigratable, dispersible, flushable, or compostable or a combination
thereof. In the present
invention, the fibers, nonwoven webs, and articles may be environmentally
degradable.
The fibers described herein are typically used to make disposable nonwoven
articles.
The articles are commonly flushable. The term "flushable" as used herein
refers to materials
which are capable of dissolving, dispersing, disintegrating, and/or
decomposing in a septic
disposal system such as a toilet to provide clearance when flushed down the
toilet without
clogging the toilet or any other sewage drainage pipe. The fibers and
resulting articles may also
be aqueous responsive. The term aqueous responsive as used herein means that
when placed in
water or flushed, an observable and measurable change will result. Typical
observations include
noting that the article swells, pulls apart, dissolves, or observing a general
weakened structure.
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The bicomponent fibers of the present invention can have low brittleness and
have high
toughness, for example a toughness of about 2MPa or greater. Toughness is
defined as the area
under the stress-strain curve.
Extensibility or elongation is measured by elongation to break. Extensibility
or
elongation is defined as being capable of elongating under an applied force,
but not necessarily
recovering. Elongation to break is measured as the distance the fiber can be
stretched until
failure. It has also been found that the fibers of the present invention can
be highly extensible.
The elongation to break of single fibers are tested according to ASTM standard
D3822
except a strain rate of 200 %/min is used. Testing is performed on an MTS
Synergie 400 tensile
testing machine with a 10 N load cell and pneumatic grips. Tests are conducted
at a rate of 2
inches/minute on samples with a 1-inch gage length. Samples are pulled to
break. Peak stress
and % elongation at break are recorded and averaged for 10 specimens.
Nonwoven products produced from the bicomponent fibers can also exhibit
desirable
mechanical properties, particularly, strength, flexibility, softness, and
absorbency. Measures of
strength include dry and/or wet tensile strength. Flexibility is related to
stiffness and can
attribute to softness. Softness is generally described as a physiologically
perceived attribute
which is related to both flexibility and texture. Absorbency relates to the
products' ability to take
up fluids as well as the capacity to retain them.
(4) Processes
The first step in producing a bi- or multi-component fiber can be a
compounding or mixing
step. In this compounding step, the raw materials are heated, typically under
shear. The shearing
in the presence of heat can result in a homogeneous melt with proper selection
of the composition.
The melt is then placed in an extruder where fibers are formed. A collection
of fibers is combined
together using heat, pressure, chemical binder, mechanical entanglement, and
combinations thereof
resulting in the formation of a nonwoven web. The nonwoven is then assembled
into an article.
Compounding
The objective of the compounding step is to produce a homogeneous melt
composition for
each component of the fibers. Preferably, the melt composition is homogeneous,
meaning that a
uniform distribution of ingredients in the melt is present. The resultant melt
compositions) should
be essentially free of water to spin fibers. Essentially free is defined as
not creating substantial
problems, such as causing bubbles to form which may ultimately break the fiber
while spinning.
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The free water content of the melt composition can be about 1% or less, about
0.5% or less, or
about 0.15% of less. The total water content includes the bound and free
water. Preferably, the
total water content (including bound water and free water) is about 1% or
less. To achieve this low
water content, the starch or polymers may need to be dried before processed
andlor a vacuum is
applied during processing to remove any free water. The thermoplastic starch,
or other components
hereof, can be dried at elevated temperatures, such as about 60°C,
before spinning. The drying
temperature is determined by the chemical nature of a component's
constituents. Therefore,
different compositions can use different drying temperatures which can range
from 20°C to 150°C
and are, in genexal, below the melting temperature of the polymer. Drying of
the components may,
for example, be in series or as discrete steps combined with spinning. Such
techniques for drying
as are well known in the art can be used for the purposes of this invention.
In general, any method known in the art or suitable for the purposes hereof
can be used to
combine the ingredients of the components of the present invention. Typically
such techniques will
include heat, mixing, and pressure. The particular order or mixing,
temperatures, mixing speeds or
time, and equipment can be varied, as will be understood by those skilled in
the art, however
temperature should be controlled such that the starch does not significantly
degrade. The resulting
melt should be homogeneous. A suitable method of mixing for a starch and
plasticizes blend is
as follows:
1. The starch is destructured by addition of a plasticizes. The plasticizes,
if solid such as
sorbitol or mannitol, can be added with starch (in powder form) into a twin-
screw extruder.
Liquids such as glycerine can be combined with the starch via volumetric
displacement pumps.
2. The starch is fully destructurized by application of heat and shear in the
extruder. The starch
and plasticizes mixture is typically heated to 120-180°C over a period
of from about 10 seconds
to about 15 minutes, until the starch gelatinizes.
3. A vacuum can applied to the melt in the extruder, typically at least once,
to remove free
water. Vacuum can be applied, for example, approximately two-thirds of the way
down the
extruder length, or at any other point desired by the operator.
4. Alternatively, multiple feed zones can be used for introducing multiple
plasticizers or blends
of starch.
5. Alternatively, the starch can be premixed with a liquid plasticizes and
pumped into the
extruder.
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As will be appreciated by one skilled in the art of compounding, numerous
variations and
alternate methods and conditions can be used for destructuring the starch and
formation of the
starch melt including, without limitation, via feed port location and screw
extruder profile.
A suitable mixing device is a multiple mixing zone twin screw extruder with
multiple
injection points. The multiple injection points can be used to add the
destructurized starch and the
polymer. A twin screw batch mixer or a single screw extrusion system can also
be used. As long
as sufficient mixing and heating occurs, the particular equipment used is not
critical.
An alternative method for compounding the materials comprises adding the
plasticizes,
starch, and polymer to an extrusion system where they are mixed in
progressively increasing
temperatures. For example, in a twin screw extruder with six heating zones,
the first three zones
may be heated to 90°, 120°, and 130° C, and the last
three zones will be heated above the melting
point of the polymer. This procedure results in minimal thermal degradation of
the starch and for
the starch to be fully destructured before intimate mixing with the
thermoplastic materials.
An example of compounding destructured thermoplastic starch would be to use a
Werner &
Pfleiderer (30 mm diameter 40:1 length to diameter ratio) co-rotating twin-
screw extruder set at
250RPM with the first two heat zones set at 50°C and the remaining five
heating zones set 150°C.
A vacuum is attached between the penultimate and last heat section pulling a
vacuum of 10 atm.
Starch powder and plasticizes (e.g., sorbitol) are individually fed into the
feed throat at the base of
the extruder, for example using mass-loss feeders, at a combined rate of 30
lbs/hour (13.6 kg/hour)
at a 60/40 weight ratio of starch/plasticizer. Processing aids can be added
along with the starch or
plasticizes. For example, magnesium separate can be added, for example, at a
level of 0 - 1 %, by
weight, of the thermoplastic starch component.
Spinning
The fibers of the present invention can be made by melt spinning. Melt
spinning is
differentiated from other spinning, such as wet or dry spinning from solution,
where in such
alternate methods a solvent is present in the melt and is eliminated by
volatilizing or diffusing it out
of the extrudate.
Spinning temperatures for the melts can range from about 105°C to about
300°C, and in
some embodiments can be from about 130°C to about 250°C or from
about 150°C to about 210°C.
The processing temperature is determined by the chemical nature, molecular
weights and
concentration of each component.
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In general, high fiber spinning rates are desired for the present invention.
Fiber spinning
speeds of about 10 meters/minute or greater can be used. In some embodiments
hereof, the fiber
spinning speed is from about 100 to about 7,000 meters/minute, or from about
300 to about 3,000
meters/minute, or from about 500 to about 2,000 meters/minute.
The fiber rnay be made by fiber spinning processes characterized by a high
draw down ratio.
The draw down ratio is defined as the ratio of the fiber at its maximum
diameter (which is typically
occurs immediately after exiting the capillary of the spinneret in a
conventional spinning process)
to the final diameter of the formed fiber. The fiber draw down ratio via
either staple, spunbond, or
meltblown process will typically be 1.5 or greater, and can be about 5 or
greater, about 10 or
greater, or about 12 or greater.
Continuous fibers can be produced through, for example, spunbond methods or
meltblowing
processes. Alternately, non-continuous (staple fibers) fibers can be produced
according to
conventional staple fiber processes as are well known in the art. The various
methods of fiber
manufacturing can also be combined to produce a combination technique, as will
be understood by
those skilled in the art. Hollow fibers, fox example, can be produced as
described in US Patent
6,368,990. Such methods as mentioned above for fiber spinning are well known
and understood in
the art. The fibers spun can be collected subsequent for formation using
conventional godet
winding systems or through air drag attenuation devices. If the godet system
is used, the fibers can
be further oriented through post extrusion drawing at temperatures from about
50° to about 200° C.
The drawn fibers may then be crimped and/or cut to form non-continuous fibers
(staple fibers) used
in a carding, airlaid, or fluidlaid process.
In the process of spinning fibers, particularly as the temperature is
increased above 105°C,
typically it is desirable for residual water levels to be 1%, by weight of the
fiber, or less, alternately
0.5% or less, or 0.15% or less.
Suitable multicomponent melt spinning equipment is commercially available
from, for
example, Hills, Inc. located in Melbourne, Florida USA and is described in US
Patent 5,162,074
(Hills Inc.).
The spinneret capillary dimensions can vary depending upon desired fiber size
and
design, spinning conditions, and polymer properties. Suitable capillary
dimensions include, but
are not limited to, length-to-diameter ratio of 4 with a diameter of 0.350mm.
As will be understood by one skilled in the art, spinning of the fibers and
compounding
of the components can optionally be done in-line, with compounding, drying and
spinning being a
continuous process.
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The residence time of each component in the spinline can have special
significance when
a high melting temperatures thermoplastic polymer is chosen to be spun with
destructured starch.
Spinning equipment can be designed to minimize the exposure of the
destructured starch
component to high process temperature by minimizing the time and volume of
destructured
exposed in the spinneret. For example, the polymer supply lines to the
spinneret can be sealed
and separated until introduction into the bicomponent pack. Furthermore, one
skilled in the art of
multicomponent fiber spinning will understand that the at least two components
can be
introduced and processed in their separate extruders at different temperatures
until introduced
into the spinneret.
For example, a suitable process for spinning bicomponent, segmented pie fiber
with at least
one destructured starch segment and at least one polypropylene segment is s
follows. The
destructured starch component extruder profile may be 80°C,
150°C and 150°C in the first three
zones of a three heater zone extruder with a starch composition similar to
Example 7. The transfer
lines and melt pump heater temperatures may be 150°C for the starch
component. The
polypropylene component extruder temperature profile may be 180°C,
230°C and 230°C in the first
three zones of a three heater zone extruder. The transfer lines and melt pump
can be heated to
230°C. In this case the spinneret temperature can range from
180°C to 230°C.
In the process of spinning fibers, particularly as the temperature is
increased above 105°C,
typically it is desirable for residual water levels to be 1%, by weight of the
fiber, or less, alternately
0.5% or less, or 0.15% or less.
(5) Articles
The fibers hereof may be used for any purposes for which fibers are
conventionally used.
This includes, without limitation, incorporation into nonwoven substrates. The
fibers hereof may
be converted to nonwovens by any suitable methods known in the art. Continuous
fibers can be
formed into a web using industry standard spunbond or meltblown type
technologies while staple
fibers can be formed into a web using industry standard carding, airlaid, or
wetlaid technologies.
Typical bonding methods include: calendar (pressure and heat), thru-air heat,
mechanical
entanglement, hydrodynamic entanglement, needle punching, and chemical bonding
and/or resin
bonding. The calendar, thru-air heat, and chemical bonding are the preferred
bonding methods
for the starch and polymer multicomponent fibers. Thermally bondable fibers
are required for the
pressurized heat and thru-air heat bonding methods.
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The fibers of the present invention may also be bonded or combined with other
synthetic
or natural fibers to malee nonwoven articles. The synthetic or natural Bbers
may be blended
together in the forming process or used in discrete layers. Suitable synthetic
fibers include fibers
made from polypropylene, polyethylene, polyester, polyacrylates, and
copolymers thereof and
mixtures thereof. Natural fibers include cellulosic fibers and derivatives
thereof. Suitable
cellulosic fibers include those derived from any tree or vegetation, including
hardwood fibers,
softwood fibers, hemp, and cotton. Also included are fibers made from
processed natural
cellulosic resources such as rayon.
The fibers of the present invention may be used to make nonwovens, among other
suitable articles. Nonwoven articles are defined as articles that contains
greater than 15% of a
plurality of fibers that are continuous, or non-continuous and physically
and/or chemically
attached to one another. The nonwoven may be combined with additional
nonwovens or films to
produce a layered product used either by itself or as a component in a complex
combination of
other materials, such as a baby diaper or feminine care pad. Preferred
articles are disposable,
nonwoven articles. The resultant products may find use in one of many
different uses. Preferred
articles of the present invention include disposable nonwovens for hygiene and
medical
applications. Hygiene applications include such items as wipes; diapers,
particularly the top
sheet or back sheet; and feminine pads or products, particularly the top
sheet.
Examples
The examples below further illustrate the present invention. The starches for
use in the
examples below are StarDri 1, StarDri 100, Ethylex 2015, or Ethylex 2035, all
from Staley
Chemical Co. The latter Staley materials are substituted starches. The
polypropylenes (PP) are
Basell Profax PH-835, Basell PDC 1298, or Exxon/Mobil Achieve 3854. The
polyethylenes (PE)
are Dow Chemicals Aspun 6811A, Dow Chemical Aspun 6830A, or Dow Chemical Aspun
6842A. The glycerine is from Dow Chemical Company, Kosher Grade BU OPTIM*
Glycerine
99.7%. The sorbitol is from Archer-Daniels-Midland Co. (ADM), Crystalline
NF/FCC 177440-
25. The polyethylene acrylic acid is PRI1VIACOR 5980I from Dow Chemical Co.
Other
polymers having similar chemical compositions that differ in molecular weight,
molecular weight
distribution, and/or comonomer or defect level can also be used.
The process condition in Examples 1-18 use a mass through put of 0.8 ghm
although actually
tested ranges are from 0.2 to 2 ghm. The practical range of mass through put
is from about 0.1 to
about 8 ghm.
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Example 1 Solid Sheath/Core Bicomponent Fiber: Thermoplastic polymer Component
A is
Basell Profax 835. Starch Component B is the TPS component and is compounded
using 60
parts StarDri 1, 40 parts sorbitol and 1 part Magnesium Stearate (included in
all starch
formulations of the examples hereof). The melt processing temperature ranges
from 180 to
210°C. The ratio of Component A to Component B is 95:5 to 10:90. An
advantage to this fiber
is that it is temperature stable to at least 140°C and has excellent
resistance to polar solvents, such
as water and alcohols.
Example 2 Solid Sheath/Core Bicomponent Fiber: Component A is Polyethylene.
Component
B is the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The
melt processing temperature ranges from 150 to 190°C. The ratio of
Component A to Component
B is 95:5 to 5:95. An advantage to this fiber is that it is temperature stable
to at least 80°C and
has excellent resistance to polar solvents, such as water and alcohols.
Example 3 Solid Sheath/Core Bicomponent Fiber: Component A is PLA. Component B
is the
TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The melt
processing temperature ranges from 180 to 210°C. The ratio of Component
A to Component B is
' 95:5 to 10:90. An advantage to this fiber is that it is temperature stable
to at least 140°C and has
excellent resistance to polar solvents, such as water and alcohols.
Example 4 Solid Sheath/Core Bicomponent Fiber: Component A is Eastman 14285.
Component B is the TPS component and is compounded using 60 parts StarDri 1
and 40 parts
sorbitol. The melt processing temperature ranges from 210 to 250°C. The
ratio of Component A
to Component B is 95:5 to 20:80. An advantage to this fiber is that it is
temperature stable to at
least 90°C and has excellent resistance to polar solvents, such as
water and alcohols.
Example 5 Solid Sheath/Core Bicomponent Fiber: Component A is Bionolle 1020.
Component
B is the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The
melt processing temperature ranges from 160 to 200°C. The ratio of
Component A to Component
B is 95:5 to 15:85. An advantage to this fiber is that it is temperature
stable to at least 80°C and
has excellent resistance to polar solvents, such as water and alcohols.
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Example 6 Solid Sheath/Core Bicomponent Fiber: Component A is EASTAR BIO.
Component
B is the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The
melt processing temperature ranges from 150 to 180°C. The ratio of
Component A to Component
B is 95:5 to 20:80. An advantage to this fiber is that it is temperature
stable to at least 80°C and
has excellent resistance to polar solvents, such as water and alcohols.
Example 7 Islands-in-the-Sea Bicomponent Fiber: Component A is Polypropylene.
Component
B is the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The
melt processing temperature ranges from 180 to 210°C. The ratio of
Component A to Component
B is 95:5 to 10:90. An advantage to this fiber is that it is temperature
stable to at least 140°C and
has excellent resistance to polar solvents, such as water and alcohols.
Example 8 Islands-in-the-Sea Bicomponent Fiber: Component A is Polyethylene.
Component
B is the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The
melt processing temperature ranges from 150 to 190°C. The ratio of
Component A to Component
B is 95:5 to 5:95. An advantage to this fiber is that it is temperature stable
to at least 80°C and
has excellent resistance to polar solvents, such as water and alcohols.
Example 9 Islands-in-the-Sea Bicomponent Fiber: Component A is PLA. Component
B is the
TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The melt
processing temperature ranges from 180 to 210°C. The ratio of Component
A to Component B is
95:5 to 10:90. An advantage to this fiber is that it is temperature stable to
at least 140°C and has
excellent resistance to polar solvents, such as water and alcohols.
Example 10 Islands-in-the-Sea Bicomponent Fiber: Component A is Eastman 14285.
Component B is the TPS component and is compounded using 60 parts StarDri 1
and 40 parts
sorbitol. The melt processing temperature ranges from 210 to 250°C. The
ratio of Component A
to Component B is 95:5 to 20:80. An advantage to this fiber is that it is
temperature stable to at
least 90°C and has excellent resistance to polar solvents, such as
water and alcohols.
Example 11 Islands-in-the-Sea Bicomponent Fiber: Component A is Bionolle 1020.
Component B is the TPS component and is compounded using 60 parts StarDri 1
and 40 parts
sorbitol. The melt processing temperature ranges from 160 to 200°C. The
ratio of Component A
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to Component B is 95:5 to 15:85. An advantage to this fiber is that it is
temperature stable to at
least 80°C and has excellent resistance to polar solvents, such as
water and alcohols.
Example 12 Islands-in-the-Sea Bicomponent Fiber: Component A is EASTAR BIO.
Component B is the TPS component and is compounded using 60 parts StarDri 1
and 40 parts
sorbitol. The melt processing temperature ranges from 150 to 180°C. The
ratio of Component A
to Component B is 95:5 to 20:80. An advantage to this fiber is that it is
temperature stable to at
least 80°C and has excellent resistance to polar solvents, such as
water and alcohols.
Example 13 Solid Sheath/Core Bicomponent Fiber: Component A is polyvinyl
alcohol
purchased from Aldrich Chemical with degree of hydrolysis between 90-99%
plasticized with
glycerine. Component B is the TPS component and is compounded using 60 parts
StarDri 1 and
40 parts sorbitol. The melt processing temperature ranges from 180-
250°C. The ratio of
Component A to Component B is 95:5 to 20:80. An advantage to this fiber is
that it is
temperature stable to at least 110°C and has excellent resistance to
non-polar solvents, such as
CC14, benzene and similar aliphatic/organic compounds.
Example 14 Solid Sheath/Core Bicomponent Fiber: Component A is polyvinyl
alcohol-co-
ethylene) purchased from Aldrich Chemical containing 27-44mo1% ethylene.
Component B is
the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The melt
processing temperature ranges from 180 to 230°C. The ratio of Component
A to Component B is
95:5 to 15:85. An advantage to this fiber is that it is temperature stable to
at least 80°C and has
excellent resistance to non-polar solvents, such as CC14, benzene and similar
aliphatic/organic
compounds.
Example 15 Solid Sheath/Core Bicomponent Fiber: Component A is a polyamide;
such as
Nylon 6, Nylon 12 and Nylon 6,10. Component B is the TPS component and is
compounded
using 60 parts StarDri 1 and 40 parts sorbitol. The melt processing
temperature ranges from 180
to 230°C. The ratio of Component A to Component B is 95:5 to 20:80. An
advantage to this
fiber is that it is temperature stable to at least 90°C and has
excellent resistance to non-polar
solvents, such as CC14, benzene and similar aliphatic/organic compounds.
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Example 16 Islands-in-the-Sea Bicomponent Fiber: Component A is polyvinyl
alcohol
purchased from Aldrich Chemical with degree of hydrolysis between 90-99%
plasticized with
glycerine. Component B is the TPS component and is compounded using 60 parts
StarDri 1 and
40 parts sorbitol. The melt processing temperature ranges from 180-
250°C. The ratio of
Component A to Component B is 95:5 to 20:80. An advantage to this fiber is
that it is
temperature stable to at least 110°C and has excellent resistance to
non-polar solvents, such as
CCI~, benzene and similar aliphatic/organic compounds.
Example 17 Islands-in-the-Sea Bicomponent Fiber: Component A is polyvinyl
alcohol-co-
ethylene) purchased from Aldrich Chemical containing 27-44 mol% ethylene.
Component B is
the TPS component and is compounded using 60 parts StarDri 1 and 40 parts
sorbitol. The melt
processing temperature ranges from 180 to 230°C. The ratio of Component
A to Component B is
95:5 to 15:85. The advantage to this fiber is that it is temperature stable to
at least 80°C and has
excellent resistance to non-polar solvents, such as CClø, benzene and similar
aliphatic/organic
compounds.
Example 18 Islands-in-the-Sea Bicomponent Fiber: Component A is a polyamide;
such as Nylon
6, Nylon 12 and Nylon 6,10. Component B is the TPS component and is compounded
using 60
parts StarDri 1 and 40 parts sorbitol. The melt processing temperature ranges
from 180 to 230°C.
The ratio of Component A to Component B is 95:5 to 20:80. An advantage to this
fiber is that it
is temperature stable to at least 90°C and has excellent resistance to
non-polar solvents, such as
CC14, benzene and similar aliphatic/organic compounds.
Examples 1-18 contain the same composition for Component B. Alternate
compositions for
Component B include, but are not limited to, those exemplified below. In the
table, Material 1
represents starch. Material 2 represents plasticizers. Material 3 represents
the non-starch
thermoplastic polymer.
Com
osition
(b parts
Com Material1 Material2Material3 Material1Material2Material3
osition
B1 Stale StarDriADM sorbitolDow Primacore60 40
1 59801
B2 Stale StarDriADM sorbitolDow Primacore60 40 15
1 59801
B3 Stale StarDriADM sorbitolDow Primacore60 40 15
100 59801
B4 Stale Eth ADM sorbitolDow Primacore60 40 15
lex 2015 59801
B5 Stale Eth ADM sorbitolDow Primacore60 40 15
lex 2035 59801
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B6 Stale StarDriDow GI Dow Primacore60 40
1 cerine 59801
B7 Stale StarDriDow GI Dow Primacore60 40 15
1 cerine 59801
B8 Stale StarDriADM sorbitolDow Primacore70 30 20
100 59801
While particular examples are given above different combinations of materials,
ratios,
and equipment such as counter rotating twin screw or high shear single screw
with venting could
also be used. While particular embodiments of the present invention have been
illustrated and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention. It is
intended to cover in the appended claims all such changes and modifications
that are within the
scope of the invention.
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