Note: Descriptions are shown in the official language in which they were submitted.
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FIBROUS PRODUCTS AND METHODS OF MANUFACTURE
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of a U.S. Provisional Application
bearing serial number 61/098,907, filed September 22, 2008, and entitled
"Fibrous
Products and Methods of Manufacture." The entire contents of the provisional
application are hereby incorporated herein by reference.
FIELD OF THE APPLICATION
This application relates generally to fibrous products formed from two or more
fiber populations.
BACKGROUND
Fibrous products containing cellulose by itself or mixed with other fibers
have
many useful applications. Among consumer applications, fibrous products such
as paper
towels are used to dry or wet clean, absorb aqueous liquids etc. Fibrous
products have
other uses for consumers and for industry, for example as filters, fabrics,
and specialized
materials having, for example, conductivity, fire resistance, and the like.
Cellulose fibers in wood pulp and other natural fibers used to make fibrous
products are typically hydrophilic, and can have limited strength and chemical
resistance. These properties can limit their use to milder environments and
can limit the
reusability of such products. Synthetic fibers may have advantages for use in
fibrous
products. Synthetic fibers are often hydrophobic. They typically have good
chemical
resistance, and may have good dry and wet strength, depending on their
chemical
structure. Synthetic fibers are also typically expensive. Moreover, to the
extent that a
synthetic fiber is fossil-fuel based, its use can have a significant
environmental impact.
As they are fossil fuel based, the environmental impact of using a fibrous
product
completely made of such synthetic fibers is high. In light of these issues, a
method is
needed where two populations of fibers, each having desirable characteristics,
could be
intimately combined to produce fibrous products.
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Many disposable, absorbent products, especially hydrophilic ones, comprise
randomly arranged webs of relatively low-density fibrous materials such as
cellulose
fibers. The random web may be produced by techniques known in the art such as
wet
laying, air laying or solvent laying of the fibers. The technique of wet
laying involves
the slurrying of the fibers in water; when the water is drawn off, the web
dries into a
final product. With wet laying, the soft and pliable fibers are attracted to
each other by
hydrogen bonding, and they sag against each other to create a denser product
than that
formed by air laying or solvent laying. The denser product formed by wet
laying may be
stronger, but it may also be less absorbent. Wet strength additives that are
employed
during manufacture may render the product more hydrophobic.
Adding hydrophobic fibers to a hydrophilic fibrous web may adversely affect
the
wicking properties and absorption capacity of the web. For example, fibrous
webs with
large proportions of uniformly distributed microfibers among the larger fibers
(e.g.,
cellulose) generally have less integrity because the microfiber component
provides less
strength than the larger fiber component, a limitation that is particularly
apparent during
applications requiring wet strength. In addition, microfibers may become
detached from
the fibrous web and form a particulate deposit on the surface being cleaned,
like lint,
fuzz, or dust.
Nonwoven products may use mechanical means for dispersing their component
fibers before coalescing them into a useful product. Manufacturing processes
may
produce staple non-wovens, where larger fibers between '/4" and 1 '/2 " may be
used
either alone or in combination with other fibers or fiber blends using a
wetlaid process or
a carding process. Manufacturing processes may also produce spunlaid non-
wovens,
where fibers are spun then directly dispersed into a web by deflectors or by
air streams.
Other manufacturing methods will be familiar to skilled artisans, such as wet-
laid mat
processes or flame-attenuated mat processes. Typically, nonwoven processes
employ a
bonding step to impart mechanical strength.
Non-woven webs have many end-uses, including formation of filtration media.
Air-laid and wet-laid processes can be used. When used for the filtration of
fluid
streams and removal of particulate matter therefrom, filtration media can be
adversely
affected by incorrect pore size, reduced efficiency, reduced permeability,
lack of
strength, or other problems arising from the nature of the non-woven web. A
need exists
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in the art, therefore, for a fibrous web suitable for filtering a variety of
fluid streams, for
example gaseous streams such as air, and aqueous and non-aqueous liquids,
including
water, wastewater, oil and the like. Desirably, such a fibrous web can possess
properties
that achieve appropriate permeability for removing designated particulate
matter,
substantial filtration efficiency, high wet strength, and long filtration
life.
Furthermore, a need exists in the art for fibrous products that are absorbent,
strong, and abrasion-resistant. A need further exists for techniques that can
easily
incorporate disparate or similar populations of fibers or microfibers into a
fibrous sheet
under a variety of manufacturing conditions to form a variety of products.
SUMMARY
Disclosed herein are embodiments of fibrous compositions of mixed fibers that
include a first population of fibers, and a second population of fibers having
native
surface characteristics differing from native surface characteristics of the
first population
of fibers, at least one population of fibers being surface modified by a
polycation, the
first and second population of fibers being mixed together in the form of a
porous
composition. The fibrous composition can include a sheet structure. The
fibrous
composition can further comprising a wet strength component. The wet strength
component can comprise at least one of a melamine-formaldehyde resin, a urea-
formaldehyde resin, and an epoxidized polyamine-polyamide resin. In
embodiments,
the polycation can comprise a polyamine, and the polycation can be bound to at
least
one fiber using a coupling agent. In embodiments, the polycations can comprise
chitosan analogues such as polycations (e.g., polyamines) modified with one or
more
types of hydrophobic side groups. In embodiments, the polycation couples at
least two
fibers together. In embodiments, at least one population of surface-modified
fibers is
attached to the polycation by at least one of electrostatic interactions,
covalent bonding,
hydrogen bonding and hydrophobic interactions.
In embodiments, the surface-modified population of fibers can comprise
synthetic fibers. In embodiments, at least one surface-modified population of
fibers can
comprise fibers exhibiting a native hydrophobic surface. The native
hydrophobic
surface can be surface modified to a hydrophilic surface. In embodiments, at
least one
population of fibers in the composition can comprise natural fibers. In
embodiments, at
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least one population of fibers can comprise at least one of micro fibers and
larger fibers.
In embodiments, at least one population of fibers can comprise fibers having
dissimilar
sizes.
In embodiments, at least one surface modified population of fibers comprises a
polysaccharide coupled to at least one of the fibers. In embodiments, at least
one surface
modified population of fibers comprises synthetic fibers having a cellulose-
based
material coupled thereto. Such compositions can further comprise a crosslinker
for
coupling the surface modification to at least one of a fiber and another
portion of the
surface modification.
In embodiments, the composition can further comprise a complementary
polymer capable of attractively interacting with the polycation. The
complimentary
polymer can comprise at least one a pectin, xanthan gum, carboxymethyl
cellulose,
polyacrylic acid, polymethacrylic acid, polyacrylamide, polyethylene glycol,
polymers
derived from maleic anhydride, and copolymer having at least one segment
comprising
any of the aforementioned polymers. In embodiments, the complementary polymer
can
comprise at least one of an epoxide, an anhydride, a carboxylic acid, and an
isocyanate.
In embodiments, the composition can comprise at least one population of fibers
comprising a fire-retardant material, an electrically conductive material, or
a
nanofibrillated cellulose-based material. In embodiments, the composition can
comprise
at least one surface-modified population of fibers that exhibits protein
adsorption
resistance relative to a native surface of the surface modified population of
fibers. In
embodiments, the composition can form at least a portion of a filter paper.
Disclosed herein are methods for forming a mixed fiber composition, comprising
attaching polycations to a first population of fibers; providing a second
population of
fibers having native surface characteristics differing from native surface
characteristics
of the first population of fibers; forming a precursor fiber composition
comprising the
first population of fibers and the second population of fibers; and creating a
sheet
structure from the precursor fiber composition. In practices of the methods,
the step of
attaching polycations can comprise precipitating the polycations onto the
first population
of fibers. The step of attaching poycations can comprise attaching a coupling
agent to
the polycations.
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Certain practices of these methods can comprise adding a wet strength
component to the fiber composition. The step of adding the wet strength
component can
take place after mixing the first population of fibers and the second
population of fibers
together. These methods can further comprise adding a complementary polymer
having
an anionic portion to the first population of fibers; and attaching the
complementary
polymer to the at least one of the polycations. According to certain practices
of these
methods, at least one population of fibers comprises synthetic fibers and at
least one
population of fibers comprises natural fibers.
DESCRIPTION
As used herein, the term "fibrous structure" or "fibrous web" refers to any
arrangement of individual fibers or filaments that are interlaid with one
another. In
some embodiments, the fibrous structure or web has a nonwoven character. In
some
embodiments, the fibers or filaments form a disorganized pattern (e.g., a
substantially
random formation or structure whose organization has little discernable
pattern). Some
techniques for fabricating fibrous structures are known in the art, including
papermaking
techniques and techniques for making nonwoven materials.
As used herein, the term "composite material" refers to a material comprising
two populations of fibers.
As used herein, the term "fiber" refers to an entity which possesses a large
aspect
ratio (e.g., a dimensional length much larger than its cross-sectional
dimension (e.g., a
diameter)). For instance, in embodiments, the aspect ratio of the fibers can
be larger
than about 10, 20, 30, 50, or 100.
As used herein, the term "microfiber" refers to synthetic or natural fiber
having a
smaller cross-sectional width and/or total length relative to a "larger
fiber," as utilized in
the present application. In some embodiments, the microfibers have an average
cross
sectional width (e.g., diameter) of no more than about 100 microns. In
embodiments, a
microfiber may have an average cross sectional width between 0.5 and 50
microns. In
other embodiments, a microfiber may have an average cross sectional width
between 4
and 40 microns. In embodiments, a microfiber may have an average cross
sectional
width less than 30 microns. The size of the microfibers can also be
characterized in
terms of denier units. In some embodiments, the microfibers, on average, are
less than
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about 10 denier, or less than about 5 denier, or less than about 2 denier, or
less than
about 1 denier.
In some embodiments, the ratio of the average cross-section dimensions (e.g.,
diameters) of the larger fibers to the microfibers can be greater than about
5, 10, 20, 50,
100, 500, 1000, 5000, or 10000.
In embodiments, microfibers may be initially dispersed in an aqueous or
solvent
medium in a range of concentrations, for example ranging from solutions in
which the
fibers are barely wetted with the medium to solutions where the fibers are
substantially
diluted by the medium.
In particular instances, at least some of the microfibers can include a fiber
having
a plurality of fibrils (i.e., a fibrillated fiber), which can potentially be
separated. A
fibrillated fiber can be produced from a fiber during fiber processing, where
a precursor
fiber is abraded or otherwise mechanically distressed. For example, processes
(e.g.,
papermaking) can increase the internal and external fibrillation of a
cellulosic pulp. A
fibrillated fiber can include portions having a cross sectional width less
than about 100
microns, though the unfibrillated fiber may have a cross sectional width
larger than
about 100 microns. Fibrils can have a nanofiber structure, e.g., exhibiting an
average
cross sectional width between about 1 nm and 1 micrometer, or between about 50
nm
and about 500 nm. In some embodiments, the microfibers are embodied as
nanofibers,
which can originate from fibrils of a microfiber.
Fibrillated fibers can be advantageously utilized in some embodiments of the
present invention. In general, the greater the fiber surface area available
for contact
within the pulp, the greater the extent of cellulose-to-cellulose hydrogen
bonding
between the fibers. This fiber-fiber bonding occurs, for example, when water
is
removed from a pulp during wet pressing and drying in papermaking. The
presence of
fibrillations can enhance the strength of a fibrous product because the
fibrils increase the
fibers' surface area and thus the potential for greater hydrogen bonding. In
addition to
potentially improving the inter fiber bonding, the fibrillation also provides
additional
surface area for retaining additives such as surface modifications.
As used herein, the term "larger fiber" refers to any synthetic or natural
fiber that
is longer and/or broader (i.e., having a larger cross sectional length) than a
microfiber.
In some embodiments, larger fibers have a cross-sectional length (e.g.,
diameter) of 3-50
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microns, 7-70 microns, or 150-600 microns, when used with smaller microfibers.
One
example of larger fibers is the cellulosic fiber associated with typical wood
pulp
formulations.
As used herein, the term "population" refers to a collection of fibers or
microfibers wherein all the fibers or microfibers are the same. The fiber type
in the fiber
population can be of any kind: e.g., synthetic, artificial or natural fibers,
larger fibers or
microfibers.
As used herein, the term "synthetic fibers" include fibers or microfibers that
are
manufactured in whole or in part. Synthetic fibers include artificial fibers,
where a
natural precursor material is modified to form a fiber. For example, cellulose
(derived
from natural materials) can be formed into an artificial fiber such as Rayon
or Lyocell.
Cellulose can also be modified to produce cellulose acetate fibers. These
artificial fibers
are examples of synthetic fibers.
Synthetic fibers can be formed from synthetic materials that are inorganic or
organic. Synthetic inorganic fibers include mineral-based fibers such as glass
fibers and
metallic fibers. Glass fibers include fiberglass and various optical fibers.
Metallic fibers
can be deposited from brittle metals like nickel, aluminum or iron, or can be
drawn or
extruded from ductile metals like copper and precious metals. Organic fibers
include
carbon fibers and polymeric fibers. Examples of polymeric fibers include
fibers made
from polyamide nylon, PET or PBT polyester, polyesters, phenol-formaldehyde
(PF),
polyvinyl alcohol, polyvinyl chloride, polyolefins, acrylics, aromatics,
polyurethanes,
elastomers, and the like. A synthetic fiber may be formed from more than one
natural or
synthetic fiber. For example, a synthetic fiber can be a coextruded fiber,
with two or
more polymers forming the fiber coaxially or collinearly. In general,
synthetic fibers
can be manufactured in any number of manners, including those known to one
skilled in
the art (e.g., solution spinning).
As used herein, the term "natural fiber" refers to a fiber or a microfiber
derived
from a natural source without artificial modification. Natural fibers include
vegetable-
derived fibers, animal-derived fibers and mineral-derived fibers.
Vegetable-derived fibers can be predominately cellulosic, e.g., cotton, jute,
flax,
hemp, sisal, ramie, and the like. Vegetable-derived fibers can include fibers
derived
from seeds or seed cases, such as cotton or kapok. Vegetable-derived fibers
can include
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fibers derived from leaves, such as sisal and agave. Vegetable-derived fibers
can
include fibers derived from the skin or bast surrounding the stem of a plant,
such as flax,
jute, kenaf, hemp, ramie, rattan, soybean fibers, vine fibers, jute, kenaf,
industrial hemp,
ramie, rattan, soybean fiber, and banana fibers. Vegetable-derived fibers can
include
fibers derived from the fruit of a plant, such as coconut fibers. Vegetable-
derived fibers
can include fibers derived from the stalk of a plant, such as wheat, rice,
barley, bamboo,
and grass. Vegetable-derived fibers can include wood fibers.
Animal-derived fibers typically comprise proteins, e.g., wool, silk, mohair,
and
the like. Animal-derived fibers can be derived from animal hair, e.g., sheep's
wool, goat
hair, alpaca hair, horse hair, etc. Animal-derived fibers can be derived from
animal
body parts, e.g., catgut, sinew, etc. Animal-derived fibers can be collected
from the
dried saliva or other excretions of insects or their cocoons, e.g., silk
obtained from silk
worm cocoons. Animal-derived fibers can be derived from feathers of birds.
Mineral-derived natural fibers are obtained from minerals. Mineral-derived
fibers can be derived from asbestos. Mineral-derived fibers can be a glass or
ceramic
fiber, e.g., glass wool fibers, quartz fibers, aluminum oxide, silicon
carbide, boron
carbide, and the like.
Disclosed herein are methods for combining two or more different populations
of
fibers so that they can together form a composite material. In embodiments,
the
composite material can be formed as a fibrous web. It is understood by those
having
ordinary skill in the art that differences in surface energies between certain
fiber
populations (e.g., hydrophobic synthetic fibers and hydrophilic cellulose
fibers) can
prevent their being combined into composite materials. Disclosed herein are
methods
for modifying the surface chemistry of such dissimilar fiber populations to
enable them
to be attached to each other to form composite materials such as fibrous webs
having
desirable properties.
In embodiments, a population of fibers of one type can first be dispersed in
an
appropriate medium and then functionalized with a polycation such as a
polyamine. As
used herein, the term "polycation" may include any polymer (e.g., copolymer)
having a
net positive charge. As used herein, the term "polyamine" may include any
polymer or
copolymer that has at least a portion of its repeat units containing an amine
(quaternary,
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ternary, secondary, or primary). In embodiments, the polyamine may desirably
contain
some repeat units with primary amines due to the reactivity of a primary
amine.
The polymers (e.g., polycations) as used herein can have an average molecular
weight which can range from 1,000 up to 10,000,000 but it is preferable to be
between
10,000 to 500,000. In other embodiments, however, polymers can include
oligomers,
e.g., having 5 or 10 to about 20 repeat units found in the corresponding
polymer. In
embodiments, a polyamine may be a polymer comprising chitosan or
polyethyleneimine.
In embodiments, a chitosan polymer may comprise a certain portion of higher
molecular
weight chitosan, i.e., chitosan with a viscosity of at least 800 cp when in a
1% acetic
acid solution. In embodiments, the amount of higher molecular weight chitosan
may be
greater than 10%, greater than 20%, or greater than 30%. Those of skill in the
art will
appreciate that for certain polymers, e.g., chitosan, an exact molecular
weight may not
be available, because such structures are defined by viscosity rather than
molecular
weight.
A process for manufacturing a composite material for fibrous webs may involve
initially dispersing a population comprising a selected microfiber, larger
fiber, or
combination thereof, in an aqueous or solvent medium such as isopropanol/water
mixtures to form a dispersion or slurry, and then functionalizing the fibers
of the
population with a polycation (e.g., polyamine), or utilizing some other binder
component
such as a wet strength component. The selected polycation may be added
directly to the
fiber or microfiber dispersion or slurry. As used herein, the term "addition
level" refers
to the weight of a polycation compared to the weight of the selected fiber or
microfiber.
In embodiments, an addition level of 0.1% to 5.0% (based on weight of the
microfiber)
is desirable, or an addition level of 0.5% to 2%.
Once a suitable concentration of fiber or microfiber polycation solution has
been
achieved, the polycation may be linked to the fiber or microfiber using a
coupling agent,
for example crosslinkers with isocyanates, epoxides, or anhydrides. Such
coupling
agents are advantageous, for example, when working with synthetic fibers or
microfibers. Any multifunctional crosslinking agent can be used that reacts
with the
polycation and the fiber or microfiber if a covalent bond is desired.
Alternatively, the
polycation may be attached to the fiber or microfiber substrate through
electrostatic,
hydrogen bonding, or hydrophobic interactions. The polycation can
spontaneously self-
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assemble onto the fiber or microfiber surface, for example, or it can be
precipitated onto
the surface.
Chitosan, for example, may be precipitated onto a fiber or microfiber surface.
Because chitosan is only soluble in an acidic solution, it may be precipitated
onto the
fibers or microfibers in a solution by adding base to a polyamine-
fiber/microfiber
dispersion until the chitosan precipitates onto the fibers or microfibers.
In embodiments, following functionalization with the polycation, one or more
complementary polymers may be added to the process. A complementary polymer
can
be any polymer that either interacts with the polycation (e.g., reacts to the
amines on a
polyamine). In the case where the complementary polymer does not react, the
interaction can either be electrostatic, hydrogen bonding, or other secondary
interaction.
Advantageously, an electrostatic interaction will be achieved, using, for
example a
polyanion such as one containing carboxylic acid groups. Examples of suitable
polyanions include biopolymers such as pectin, xanthan gum, and carboxymethyl
cellulose and synthetic polymers such as polyacrylic acid or polymethacrylic
acid.
Copolymers can also be used, for example those that contain repeat units with
anionic
charge.
In the case where the complementary polymer reacts with the functionalities on
the polycation (e.g., amines on a polyamine), the complementary polymer can
contain
repeat units with any group that reacts with polycation functionality. In the
case of
amines on a polyamine, such groups include but are not limited to epoxides,
anhydrides,
carboxylic acids, and isocyanates. In embodiments, copolymers may be used that
contain some repeat units with reactive groups, for example reactive groups
like those
mentioned above. The molecular weight of the polymer may advantageously be
between 1,000 and 10,000,000 Daltons, for example between 10,000 and 500,000.
As would be understood by skilled artisans, secondary polymers can also be
added that interact with the complementary polymers. Such secondary polymers
can
impart specific functionality to the composite, or they can stabilize it or
improve its
properties in other ways. For example, secondary polymers can include
copolymers
containing ionic groups, or containing hydrophobic groups such as styrene
maleic
anhydride or styrene maleimides, or the like, which can be specifically
precipitated onto
fibers using changes in pH, thereby providing a water-resistant layer on the
fiber
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surfaces. Secondary polymers also can be added after the fiber assembly is in
place, so
that they form a passivation layer and change the surface properties of the
resulting
sheet. In embodiments, secondary complementary polymers can include proteins
such
as zein (from corn), which can be precipitated onto the composite by pH
change. Such
proteins are hydrophobic in nature and are grease-resistant, lending these
desirable
properties to a composite material.
In embodiments, the complementary polymer may enhance the strength of the
composite. In other embodiments, the complementary polymer may contain
functionality that can impart properties besides strength enhancement. For
example,
elastic polymers or copolymers can be used to change the resulting product's
stiffness or
wear resistance, or hydrophobic polymers or copolymers can be used to change
the
water contact angle. Combinations of suitable polymers can also be used. The
addition
level is preferred to be from 0. 1% to 5.0% (based on microfiber weight) and
further
preferred between 0.5% and 2%.
After a first population of fibers or microfibers has been functionalized, and
after
a complementary polymer has been added, a second population of non-
functionalized
fibers or microfibers can be added to the mixture. A wet-strength agent can
then be
added to the mixture to bind the two populations of fibers together for the
formation of a
fibrous sheet or web. The second population of non-functionalized fiber can
include any
fiber or microfiber. Not to be bound by theory, it is understood that the
functionalization
of the first fiber population before its addition to the second population of
fibers can
minimize the electrostatic repulsion that might otherwise exist between the
two fiber
populations. These methods can thus permit the admixture of dissimilar types
of fibers
for the formation of a fibrous web or sheet.
In some embodiments, after addition of any complementary polymer, a treated
microfiber may be mixed with larger fibers to form a mixture, for example a
slurry.
Mixing techniques may involve any technique familiar to skilled artisans, for
example
mixing in solution or mechanical mixing. In embodiments, the larger fibers may
comprise any fibrous material. As an example, larger fibers may comprise
cellulosic
fibers, e.g., wood pulp. From this microfiber-larger fiber mixture, a fibrous
web may be
produced, for example as a sheet, using techniques familiar to skilled
artisans. As an
example, synthetic fibers or microfibers treated with chitosan could be
combined with
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cellulose wood pulp with a wet strength agent to produce cleaning towels with
an
increased surface area and oleophobicity that helps in cleaning oily spills.
The ratio of
microfiber to larger fiber as a percentage by weight can range widely to
achieve
specifications for a particular product. In embodiments, the ratio of
microfiber to larger
fiber may approach 0%, or it may approach 100%. Appropriate ratios for
specific
articles of manufacture may be determined by skilled artisans using no more
than routine
experimentation. In alternative embodiments, the larger fiber can be treated
by any of
the techniques discussed herein before being mixed with microfibers, which may
or may
not be treated.
In embodiments, a mixture whose fibrous component contains between 10% to
60% microfiber by weight may provide advantages for performance and/or cost-
effectiveness. For example, the microfibers can help maintain product
integrity during
both wet and dry cleaning, or may reduce particulate shedding. Use of
hydrophilic
microfibers may enhance absorptive or fluid retention. Microfibers may
increase the
strength of the sheet during wet or dry uses. Other performance advantages may
be
readily appreciated by those of ordinary skill in the art, and these
advantages may be
readily attained using no more than routine experimentation.
In embodiments, a wet strength chemical may be added to the mixture at a level
of 0.05% to 5.0% (based on weight of all fiber) but preferably from 0.2% to
2%. Wet
strength chemicals include commercially available agents used in papermaking
to aid in
immobilization of bonds between fibers in a wet state by covalent bond
formation.
Examples of wet strength chemicals include melamine-formaldehyde resins, urea-
formaldehyde resins, and epoxidized polyamine-polyamide resins, and other such
chemicals known to those skilled in the art. To enhance wet strength or other
properties,
any prepolymer or polymer can be added that covalently binds the treated
microfibers to
the other fibers. Examples of specific wet strength chemicals include the
chemical
series with the trade name, Kymene (made by Hercules).
In order to functionalize microfibers according to these methods to combine
them with larger fibers, any process that disperses the microfibers
appropriately can be
used to apply the polymers to the microfibers. Processes include various
mixing
processes such as pulping, shear mixing, stirring. In addition to mechanically
mixing,
any other known dispersion process can be used such as blowing a gas into the
fibers.
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The treated microfibers can be mixed in with the fibers using any known
process. In
embodiments, any known mixing process may be used for any of the steps. In
other
embodiments, specific mixing processes may be devised and adapted for the
technology
by skilled artisans, using no more than routine experimentation. In
embodiments, the
treated microfibers may be produced first, then combined with larger fibers to
make the
fibrous product. In embodiments, the treated fibers may be added to a fibrous
product
that has already been partially formed. Variations will be readily apparent to
those of
ordinary skill in the art.
Some particular embodiments are drawn to methods for forming fiber
compositions or composite materials by treating at least two populations of
fibers or
microfibers in different manners. In some embodiments, one population of
fibers is
treated with a polycation component, such as any type of, or combination of,
polyamine
as described within the present application (e.g., chitosan and/or a
polyalkyleneimine
having 2 to 10 carbon atoms in the backbone per repeat unit). Another
population of
fibers can exhibit a net negative charge. For instance, the net negative
charge can be
inherent to the fiber population (e.g., cellulosic fibers), or the fibers can
be treated in a
manner such that a net negative charge is imparted (e.g., having polyanions
attached to
the fibers such as any combination of types of complementary polymers
discussed in the
present application). These two populations can be combined in a mixture,
which can
subsequently be used to form a fiber composition, such as forming a sheet of a
paper-
based material. While not necessarily being bound by any particular theory,
such
embodiments can result in a fiber composition that has enhanced strength,
and/or
abrasion resistance, relative to subjecting both populations to exactly the
same
conditions because of the electrostatic attraction between the different net
charged
fibers.
In various embodiments, the population of fibers that are treated with a
polycation can be a population of microfibers or a population of larger
fibers. For
example, microfibers can be treated with a polycation (e.g. one or more
polyamines)
while larger fibers can exhibit the net negative charge. Also, the types of
fibers used in
various fiber populations can be of any type, such as those disclosed in the
present
application (e.g., naturally-occurring fibers such as cellulosic fibers,
and/or synthetic
fibers such as polypropylene fibers, and/or fibers that comprise a plurality
of fibrils that
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are held together or separated). For example, one fiber population may
comprise Nomex
fibers for improved fire retardancy, metallic fibers for improved
conductivity, ferrous
fibers for magnetic properties.
In an embodiment, two populations of fibers that are substantially similar in
size
and base chemical nature (e.g., cellulosic fibers having the same average
diameter and
length) can be used with one being treated with a polycation (e.g., polyamine)
and the
other being untreated. As well, more than two populations of fibers can be
treated in
various manners. It is apparent that these embodiments can utilize any of the
other
features described in other embodiments of the present invention (e.g., the
use of wet
strength components, complementary polymers, coupling agents, etc.).
Though several embodiments described herein refer to treating and treated
microfibers, aspects of the present application also include utilizing any
combination of
the treatments described herein on the larger fiber component. In some
embodiments,
treatment of larger fibers can be accomplished with synthetic long fibers.
Exemplary
treatments include the addition of polycations (e.g., polyamines), coupling
agents,
complementary polymers, secondary polymers, and wet strength agents, among
others.
In other embodiments, each population can be subjected to a different type of
treatment
(e.g., one population treated with polyamine, the other population being
treated with a
complementary polymer).
The methods for treating fiber populations disclosed herein can enable the
manufacture of products having distinct and advantageous properties. For
example,
synthetic microfibers can be mixed with cellulosic woodpulp longer fibers
after carrying
out the treatments disclosed herein, and their mixture can be used to create
filtration
membranes. In such a product, the surface area and the porosity of the
filtration
membrane would be determined by the selection of an appropriate microfiber,
and/or the
determination of the ratio of microfibers to longer fibers. By selecting
fibrillated nano-
and microfibers, for example, a filtration membrane can be produced with a
specific
porosity and surface chemistry. In embodiments, the porosity can be controlled
by
adding a preselected amount of nano- or microfibers to the manufacturing
process, with
treatments as disclosed herein. In embodiments, the surface chemistry of the
cellulosic
and synthetic fibers can be changed by attaching selected polymers to the
fiber surface
to make them more hydrophilic or hydrophobic (e.g., chitosan analogs). For
filtration
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membranes and other applications where low protein binding is necessary (such
as
biological applications and medical applications), synthetic and natural
fibers can have
further surface modifications, using, for example, polymers that contain PEG-
like
moieties (Jeffamines, Pluronics, Tectonics, chitosan analogs, and the like).
In another embodiment, the synthetic fibers can be coated with a
polysaccharide
layer, so that the synthetic fibers possess surface characteristic of regular
wood pulp.
Fibers modified in this way can mimic the surface properties of natural pulp
fibers,
while possessing the mechanical and thermal properties of synthetic materials
from
which they are made. Exemplary fibers can have a long axis and a small
diameter, so
that their aspect ratio is large. An aggregation of such fibers, having a
large aspect ratio,
can form what is termed a percolation network even though present in very
dilute, low
loading levels in the final mixture. As a result of the scaffolding effect of
the
percolation network, a paper made using such fibers can be very strong. A
paper made
using such fibers can also be light in weight if lower density fibers are
used, e.g.,
polyolefins and the like.
Cellulosic molecules and polysaccharides such as carboxymethylcellulose,
dextran, various gums such as xanthan gum, gum Arabic can be used to modify
the
surfaces of synthetic fibers. As the synthetic fibers often lack the
functionalities for easy
chemical modification and attachment, an intermediate layer can be provided
such that it
attaches the polysaccharide or cellulosic molecules to the surface of the
synthetic fibers.
As an example, the desired synthetic fibers can be initially coated with a
layer of
polycations such as chitosan or similar polyamines or substituted polyamines
and then
exposed to anionic polysaccharide derivatives. The surface of the synthetic
fibers can be
electrostatically modified using this method so that it possesses advantageous
properties
of cellulose fibers, such as are found in regular wood pulp. Fibers modified
using this
method can also be further stabilized by crosslinking the cellulosic molecule
to the
surface of synthetic fibers by using traditional crosslinkers such as glyoxal,
glutaraldehyde.
Such mixtures of coated synthetic fibers and natural pulp fibers can
furthermore
be assembled together using certain of the methods set forth herein. In other
embodiments, a synthetic fiber such as polyester can be spun and cut to
produce short
fiber strands that mimic the dimensions of the cellulosic fibers used, for
example, in
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paper manufacture. The synthetic fibers can then be coated with a layer of
cellulose or
cellulosic materials, such as dextran, starch, alkoxy-substituted cellulose,
carboxymethy-
cellulose, or other derivatized cellulosic materials.
In embodiments, the overcoat layer can be internally crosslinked and/or
anchored
on polyester with well known crosslinkers such as polyacrylic acid, DMDHEU,
and
BTCA, etc. Crosslinking can attach the overcoat to the fiber securely, so that
it is not
dislodged during slurry formation and papermaking. The resulting synthetic-
based
modified fibers can mimic natural fibers in dimension and in surface
characteristics.
They can thus be evenly distributed throughout a paper product, so that a
paper product
formed from them can resemble one made from natural fibers. In a state of full
dispersion, where most of the modified fibers exist in isolation except for
point contacts
with other co-existing components, the aspect ratio (length vs. diameter) of
such fillers
can be large, so even a small volume fraction loading of the modified
synthetic fibers
can create a continuous network over a macroscopic sample. The continuous
reinforcement network leads to enhanced mechanical performance. In embodiments
where such coated fibers are more or less randomly oriented in the x,y plane
(thus
exhibiting an even in-plane angular distribution), the resulting products can
also
demonstrate greatly enhanced puncture resistance and tear resistance.
In yet other embodiments, a modified synthetic fiber can be created having a
hydrophilic surface that is charged or that possesses a high level of
hydration when
mixed into the slurry. For example, a polymeric fiber such as a polyester or a
polyamide
(e.g., nylon) having a neutral charge can be given a highly hydrophilic
surface treatment
by anchoring a molecular network made of a hydrophilic polymer (such as
polyacrylic
acid) on the fiber surface. Other examples will be appreciated by artisans
having
ordinary skill in the art. Such modified fibers can be dispersed evenly
throughout a
system, because they do not tend to aggregate. Moreover, since the modified
fibers do
not bunch up, the high aspect ratio intrinsic to individual fibers is
preserved, allowing
the fibers to be used as effective reinforcement agents. In embodiments,
surface
modifications are performed as a separate, "off-line" step, with the modified
fibers being
introduced into the paper-making slurry only thereafter.
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Other embodiments are drawn to chitosan analogues that can be prepared with
synthetic polyamines, which can be used with any appropriate embodiment
herein.
Chitosan analogues refer to polymers (e.g., polycations) that, like chitosan,
can be in
solution at a pH below a given threshold and can precipitate out of solution
when the pH
is raised above the threshold. The pH threshold can be selected to be any
value, e.g., a
value above a pH of about 2, 3, 4, 5, or 6, and/or a pH below about 6, 7, 8,
9, or 10. One
instance of a chitosan analogue refers to hydrophobically modified polycations
(e.g.,
polyamines) that can be utilized with embodiments herein, i.e., modifying a
non-
chitosan polycation (e.g., polyamine excluding chitosan) with a hydrophobic
group in a
manner to act as a chitosan analogue. The degree of substitution can control
the pH
transition point. For example, polyvinylamine (Lupamin 9095, BASF) can be
modified
with hydrophobic side groups by the use of monoepoxy functionalized alkyl
chains of
varying length by dissolving various amounts of the epoxy functionalized
compound
with polyvinylamine in a common solvent such as acetone. The stoichiometry of
substitution of the alkyl chain onto the polyvinylamine backbone can be
controlled by
the amount of the epoxy functionalized alkyl chain in the reaction mixture.
In another example, polyvinylamine (Lupamin 9095, BASF) can be modified
using epoxy functionalized polyethyleneoxide (PEO) and polypropyleneoxide
(PPO)
polymers by dissolving the polymers in a common solvent such as acetone. The
PEO
and PPO polymers exhibit lower critical solution temperatures (LCST), which
can be
exploited to alter the solution behavior of modified polyvinylamines. By
varying the
ratio of PEO to PPO attached to the polyamine backbone, the transition
temperature at
which the modified polyamine precipitates in the aqueous solution can be
controlled.
The choice of polyamine would not be not limited to polyvinylamine but is
inclusive of
polyamines such as polyethyleneamine (branched or linear) and polyallylamine.
Still other embodiments can be directed to polyamines modified with PEO and/or
PPO segments. For example, a modified polyvinylamine, prepared according any
of the
methods described herein, can be dissolved in water and the temperature of the
solution
was initially cooled to about 5 C and then slowly raised to 90 C and the
temperature at
which the solution turns cloudy or turns clear from cloudy is noted.
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Some embodiments of the present invention are direct to handsheets having fire-
retardant properties. For instance, Nomex meta-aramid fibers of 2mm length at
2
denier can be mixed with cellulose woodpulp, e.g., prepared according to the
protocol
described in Examples 2 and 9 below. Nomex is understood to have fire-
resistant
properties when incorporated into fabrics or sheets. A handsheet prepared
according to
the aforesaid method using Nomex fibers would be expected to demonstrate fire-
resistant properties.
Other embodiments are directed to compositions that impart protein adsorption
resistance to a fibrous composition. For instance, samples, e.g., prepared in
accord with
the techniques described in Example 9 below, can be treated with 1% solution
of
polyetheramine such as Jeffamine XTJ502 (Huntsman Chemicals) by dipping the
handsheet in the solution for 10 min. The handsheet can be removed from the
beaker,
rolled between 2 couch sheets to remove excess water and dried. Alternately,
polyethyleneglycol-containing polymers with anhydride or epoxy function groups
could
be used to prepare handsheets. Specifically, handsheets, e.g., prepared in
Example 9
below, can be dipped in polyethyleneglycol diglycidylether at 1% in water for
10 min.
The handsheets can be removed from the solution, rolled between 2 couch sheets
to
remove excess water and dried. The amine-functionalized handsheets prepared
according to these methods would be expected resist protein adsorption,
because the
polymers incorporated into the paper can prevent the binding of proteins to
the
underlying cellulose surfaces.
Some embodiments are directed to preparing handsheets having conductive
properties. For instance, handsheets can be prepared, e.g., according to the
protocol in
Examples 2 and 9 below, using metallic fibers. In a particular example, fibers
such as
metallized polyester yarn (Melton Corp) and Lurex brand aluminized polyester
and
Nylon yarns from Lurex Co. Ltd can be used. Because of the conductive
properties of
the metallic fibers, a handsheet prepared according to the aforesaid examples
would be
expected to have conductive and anti-static properties.
Other embodiments are direct to preparing filter papers. Advanced filter
papers
can be made using the formulations and methods described in the present
application.
Filter papers, which are cellulosic in nature, could be strengthened using
polysaccharide-
coated synthetic fibers such that the chemical nature of fibers is unaffected
while
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improving the burst strength of the filter paper. For instance, filter papers
could be made
using procedure as described in Examples 2 and 9 below using different
microfibers to
impart different functionalities to the filter paper. Use of synthetic
microfibers such as
polyolefin fibers or Nylon/polyester bicomponent fibers imparts hydrophobicity
to the
filter paper which can be used to trap hydrophobic moieties present in water
including
proteins, allowing more expensive 100% synthetic filters to be replaced with
inexpensive synthetic/cellulose composite filters. Further, the amine
functionalized
synthetic fibers can be functionalized with specific molecules such as metal-
chelating
agents, antibodies, and the like, to produce "intelligent" filtration
membranes to
selectively remove desired contaminants. In addition to the above advantages,
synthetic
microfibers can also provide higher surface area and an ability to control the
pore size of
the filtration membrane that is not possible by coarser cellulose fibers. In
addition, the
procedure outlined earlier could be used to impart protein resistance to
filtration
membranes to prevent clogging of pores by protein based films leading to loss
of
filtration efficiency.
Yet other embodiments are directed to the use of nanofibrillated cellulose to
produce stronger paper. The strength of papers made with cellulose can be
limited
because the contact points between the cellulose fibers due to hydrogen
bonding are
limited in number. Paper strength can be improved by the use of smaller
cellulose fibers
made using fibrillation. Nanofibrillated wood pulp fibers (Engineered Fibers
Technology, LLC) could be used to increase effective surface area of fibers
and to
increase hydrogen bonding density between fibers by increasing the number of
contacts
between more flexible nano fibers and coarser cellulose wood pulp fibers.
Composite
products made in this way could be further strengthened by the procedures
detailed in
Examples 2 and 9 below.
EXAMPLES
The examples that follow illustrate some of the systems and methods disclosed
herein by describing certain embodiments and features of fibrous webs and
sheets
manufactured in accordance with these systems and methods. The Examples are in
no
way intended to limit the scope of the present invention. In the Examples
provided,
certain of the following materials were used, as described in more detail
below.
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MATERIALS
Acrylic Microfiber
Engineered Fibers Technology, A010-4
Shelton, CT
Chitsan cg800
Primex
Siglufjodur, Iceland
Chitosan eg110
Primex
Siglufjodur, Iceland
Kymene 557H
Hercules 96-23-1
Wilmington, DE
Lyocell Microfiber
Engineered Fibers Technology, LO 10-4, L040-6
Shelton, CT
Nylon/PET Microfiber
Poly(acrylamide-co-acrylic acid), Partial Sodium Salt
Aldrich 411471-25OG
Milwaukee, WI
Poly(ethylene glycol) diglycidyl ether
Aldrich 475696
St. Louis, MO
Poly[(isobutylene-alt-maleic acid), ammonium salt-co-(isobutylene-alt-maleic
anhydride)]
Aldrich 531367-25OG
St. Louis, MO
Polypropylene Microfiber
HILLS, Inc.
W. Melbourne, FL
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Larger Fiber
Softwood Pulp Cellulose Fibers
Blotting sheets
Kalamazoo Paper Chemicals
Richland, MI
EXAMPLE 1: Larger Fiber Pulp Preparation
A 5% slurry was prepared by blending 20 g refurnished long fibers in 400 mL of
water. The slurry was diluted to 0.5% pulp by adding 3.6 L of water.
EXAMPLE 2: Microfiber Pulp Preparation
A 5% slurry was prepared by blending 20 g lyocell microfibers (L010-4, L040-6,
acrylic, polypropylene, or nylon/PET) in 400 mL of water. The slurry was
diluted to
0.5% pulp by adding 3.6 L of water.
EXAMPLE 3: Handsheet Preparation
Handsheets were prepared using a Mark V Dynamic Paper Chemistry Jar and
Hand-Sheet Mold from Paper Chemistry Laboratory, Inc. (Larchmont, NY). The
appropriate volume of 0.5% pulp slurry (50/50 slurry, long fiber slurry or
microfiber
slurry) was functionalized with up to 2% the of the appropriate polymer(s)
(based on dry
weight). Polymer additions were done at 10 minute intervals. This combined
slurry was
diluted with water up to 2 L and added to the handsheet maker. The slurry was
mixed at
a rate of 1100 RPM for 5 seconds, 700 RPM for 5 seconds, and 400 RPM for 5
seconds.
The water was then drained off. The subsequent sheet was then transferred off
of the
wire, pressed and dried.
EXAMPLE 4: Abrasion Testing
Abrasion tests were performed on the handsheets by wetting the sheet and using
a 2 kg weight to rub the sheet across black felt ten times. The amount of lint
left on the
felt by the sheet was turned into a percentage where 0% was no lint and 100%
was the
weight tearing through the sheet leaving lint that covered most of the rubbed
area.
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EXAMPLE 5: Mixed Fiber Pulp Slurry Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 1 combined with 150 mL of material from
Example 2
(LO 10-4). The abrasion test could not be performed because of inadequate wet
strength.
The wet tensile strength was 0.885 lbf/in at the max load/width. The wet to
dry strength
was 10.8%.
EXAMPLE 6: Mixed Fiber Pulp Slurry with Chitosan Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 1 combined with 150 mL from Example 2 (LO10-4)
and adding 1.5 mL of a I% CG800 chitosan solution. The abrasion test could not
be
performed because of inadequate wet strength. The wet tensile strength was
2.098 lbf/in
at the max load/width. The wet to dry strength was 17.2%.
EXAMPLE 7: Mixed Fiber Pulp Slurry with Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 1 combined with 150 mL from Example 2 (LO 10-
4).
To this 0.12 mL of 12.5% Kymene 557 solution was added. The abrasion test left
30%
of the felt covered. The wet tensile strength was 5.456 lbf/in at the max
load/width. The
wet to dry strength was 47.1 %.
EXAMPLE 8: Microfiber with Chitosan and Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 2 (LO10-4) and adding 0.75 mL of a 1% CG800
chitosan solution. The slurry was then combined with 150 ml of the material
from
Example 1. To this 0.12 mL of 12.5% Kymene 557 solution was added. The
abrasion
test left 5% of the felt covered in lint. The wet tensile strength was 6.836
lbf/in at the
max load/width. The wet to dry strength was 54.4%.
EXAMPLE 9: Microfiber with Chitosan, Polyacrylamide and Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 2 (LO 10-4) and adding 0.75 mL of a I% CG800
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chitosan solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide) solution. The slurry was then combined with 150 mL of the material
produced in Example 1. To this 0.12 mL of 12.5% Kymene 557 solution was added.
The abrasion test left I% of felt covered in lint. The wet tensile strength
was 5.769
lbf/in at the max load/width. The wet to dry strength was 52.6%.
EXAMPLE 10: Long Fiber with Chitosan, Polyacrylamide and Kymene Handsheet
Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 1 and adding 0.75 mL of a I% CG800 chitosan
solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide)
solution. The slurry was then combined with 150 mL of the material produced in
Example 2 (L010-4). To this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 11: 6mm Microfiber with Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 1 combined with 150 mL of material from
Example 2
(L040-6). To this 0.12 mL of 12.5% Kymene 557 solution was added. The abrasion
test
left 20% of the felt covered. The wet tensile strength was 4.426 lbf/in at max
load/width. The wet to dry strength was 36.7%.
EXAMPLE 12: 6mm Microfiber with Chitosan, Poly(acrylamide-co-acrylic acid) and
Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of the material from Example 2 (L040-6) and adding 0.75 mL of a I% CG800
chitosan solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide) solution. The slurry was then combined with 150 mL of the material
produced in Example 1. To this 0.12 mL of 12.5% Kymene 557 solution was added.
The abrasion test left 20% of the felt covered. The wet tensile strength was
4.426 lbf/in
at max load/width. The wet to dry strength was 36.7%.
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EXAMPLE 13: Acrylic Microfiber with Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
(acrylic). To this 0.12 mL of a 12.5% Kymene solution was added. The abrasion
test
left 1% of the felt covered in lint. The wet tensile strength was 6.574 lbf/in
at the max
load/width. The wet to dry strength was 67.3%.
EXAMPLE 14: Acrylic Microfiber with Chitosan, Poly(acrylamide-co-acrylic acid)
and
Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (acrylic) and adding 0.75 mL of a 1% CG800
chitosan
solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide)
solution. The slurry was then combined with 150 mL of material produced in
Example
1. To this 0.12 mL of a 12.5% Kymene solution was added. The abrasion test
left I% of
the felt covered in lint. The wet tensile strength was 4.911 lbf/in at the max
load/width.
The wet to dry strength was 67.9%.
EXAMPLE 15: Polypropylene Microfiber with Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
(polypropylene). To this 0.12 mL of a 12.5% Kymene solution was added. The
abrasion test could not be performed because of inadequate wet strength. The
wet
tensile strength was 0.434 lbf/in at the max load/width. The wet to dry
strength was
35.6%.
EXAMPLE 16: Polypropylene Microfiber with Chitosan, Poly(acrylamide-co-acrylic
acid) and Kymene Handsheet Tests
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (polypropylene) and adding 0.75 mL of a 1% CG800
chitosan solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide) solution. The slurry was then combined with 150 mL of material
produced
in Example 1. To this 0.12 mL of a 12.5% Kymene solution was added. The
abrasion
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test left 10% of the felt covered in lint. The wet tensile strength was 1.4
lbf/in at the
max load/width. The wet to dry strength was 85.3%.
EXAMPLE 17: Mixed Fiber Pulp Slurry with Chitosan and Polyanhydride
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
(L010-4) and adding 1.5 mL of a 1% CG800 chitosan solution. To this 1.5 mL of
a 1%
maleic anhydride copolymer solution was added.
EXAMPLE 18: Mixed Fiber Pulp Slurry with Chitosan and Epoxide
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
(LO 10-4) and adding 1.5 mL of a 1 % CG800 chitosan solution. To this 1.5 mL
of a 1 %
polyethylene glycol diglycidyl ether solution was added.
EXAMPLE 19: Mixed Fiber Pulp Slurry with Chitosan and Polyanhydride
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
(L010-4) and adding 1.5 mL of a 1% CG800 chitosan solution. After the sheet
was
formed, it was dipped into a 1% solution of a maleic anhydride copolymer.
EXAMPLE 20: Mixed Fiber Pulp Surry with Chitosan and Jeffamine Substituted
Polyanhydride
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example I combined with 150 mL of material from Example 2
(LO 10-4) and adding 1.5 mL of a 1% CG800 chitosan solution. To this 1.5 mL of
a
maleic anhydride copolymer was added with 25% of the anhydrides substituted
with
jeffamine.
EXAMPLE 21: Mixed Fiber Pulp Slurry with High pH
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 1 combined with 150 mL of material from Example 2
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(L010-4) and adding 1.5 mL of a 1% CG800 chitosan solution. To this 0.1 M NaOH
was added until the pH reached 8 and then 1,5 mL of 1% maleic anhydride
solution was
added.
EXAMPLE 22: Microfiber with Half Chitosan, Poly(acrylamide-co-acrylic acid)
and
Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (LO10-4) and adding 0.375 mL of a 1% CG800
chitosan
solution and then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide)
solution. The slurry was then combined with 150 mL of material from Example 1.
To
this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 23: Microfiber with Chitosan, Half Poly(acrylamide-co-acrylic acid)
and
Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (L010-4) and adding 0.75 mL of a I% CG800
chitosan
solution and then 0.375 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide)
solution. The slurry was then combined with 150 mL of material from Example 1.
To
this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 24: Microfiber with Chitosan, Polyacrylic acid and Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (L010-4) and adding 0.75 mL of a 1% CG800
chitosan
solution and then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylic acid)
solution. The slurry was then combined with 150 mL of material from Example 1.
To
this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 25: Microfiber with Short Chitosan, Polyacrylamide and Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (LO 10-4) and adding 0.375 mL of a 2% CG 110
chitosan
solution and then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide)
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solution. The slurry was then combined with 150 mL of material from Example 1.
To
this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 26: Microfiber with Chitosan, Larger Fibers with Poly(acrylamide-co-
acrylic acid), Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (L010-4) and adding 0.75 mL of a 1 % CG800
chitosan
solution. Separately, 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide) was added to 150 mL of the material produced in Example 1. The two
slurries were then combined. To this 0.12 mL of 12.5% Kymene 557 solution was
added.
EXAMPLE 27: Microfiber with Chitosan, Polymaleic anhydride and Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (LO10-4) and adding 0.75 mL of a 1% CG800
chitosan
solution and then 0.75 mL of a 1% maleic anhydride copolymer solution. The
slurry
was then combined with 150 mL of material from Example 1. To this 0.12 mL of
12.5%
Kymene 557 solution was added.
EXAMPLE 28: 4% Microfiber Slurry
Two handsheets were produced according to the method of Example 3 using 15 g
of a 5% microfiber slurry (LO 10-4) that was diluted with 3.75 mL of water. To
this
slurry 0.75 mL of a 1% CG800 chitosan solution and then 0.75 mL of a 1%
poly(acrylamide-co-acrylic acid) (80% acrylamide) solution. The slurry was
then
combined with 150 mL of material from Example 1. To this 0.12 mL of 12.5%
Kymene
557 solution was added.
EXAMPLE 29: 1% Microfiber Slurry
Two handsheets were produced according to the method of Example 3 using 15 g
of a 5% microfiber slurry (LO10-4) that was diluted with 60.25 mL of water. To
this
slurry 0.75 mL of a I% CG800 chitosan solution and then 0.75 mL of a I%
poly(acrylamide-co-acrylic acid) (80% acrylamide) solution. The slurry was
then
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combined with 150 mL of material from Example 1. To this 0.12 mL of 12.5%
Kymene
557 solution was added.
EXAMPLE 30: 3% Microfiber Slurry
Two handsheets were produced according to the method of Example 3 using 15 g
of a 5% microfiber slurry (LO10-4) that was diluted with 10.75 mL of water. To
this
slurry 0.75 mL of a 1% CG800 chitosan solution and then 0.75 mL of a 1%
poly(acrylamide-co-acrylic acid) (80% acrylamide) solution. The slurry was
then
combined with 150 mL of material from Example 1. To this 0.12 mL of 12.5%
Kymene
557 solution was added.
EXAMPLE 31: 50% Mixture of Low and High Molecular Weight Chitosan
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (L010-4) and adding 0.75 mL of a chitosan
solution.
The chitosan solution was premixed to make a 50% CG800 and 50% CG110 solution.
To this 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80% acrylamide)
solution
was added. The slurry was then combined with 150 mL of material from Example
1.
To this 0.12 mL of 12.5% Kymene 557 solution was added.
EXAMPLE 32: Microfiber with Chitosan, Polyanhydride and Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (LO10-4) and adding 0.75 mL of a 2% CG 110
chitosan
solution and then 0.75 mL of a 1% poly[(isobutylene-alt-maleic acid), ammonium
salt-
co-(isobutylene-alt-maleic anhydride)]. The slurry was then combined with 150
mL of
material from Example 1. To this 0.12 mL of 12.5% Kymene 557 solution was
added.
EXAMPLE 33: Nylon/PET Microfiber with Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example I combined with 150 mL of material from Example 2
(nylon/PET). To this 0.12 mL of a 12.5% Kymene solution was added.
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EXAMPLE 34: Nylon/PET Microfiber with Chitosan, Poly(acrylamide-co-acrylic
acid)
and Kymene
Two handsheets were produced according to the method of Example 3 using 150
mL of material from Example 2 (nylon/PET) and adding 0.75 mL of a 1% CG800
chitosan solution then 0.75 mL of a 1% poly(acrylamide-co-acrylic acid) (80%
acrylamide) solution. The slurry was then combined with 150 mL of material
produced
in Example 1. To this 0.12 mL of a 12.5% Kymene solution was added.
EQUIVALENTS
While specific embodiments of the subject invention have been discussed, the
above specification is illustrative and not restrictive. Many variations of
the invention
will become apparent to those skilled in the art upon review of this
specification. For
instance, embodiments of the present invention can utilize any combination of
features
from other embodiments combined in any feasible permutation to provide other
aspects
of the present invention. In one example, microfibers and/or larger fibers can
be treated
with any one or more of the components described herein, such as polycations,
complementary polymer, secondary polymer, wet strength chemical, etc. In a
particular
example, microfibers and larger fibers can be treated by Kymene and no other
components. The full scope of the invention should be determined by reference
to the
claims, along with their full scope of equivalents, and the specification,
along with such
variations.
Unless otherwise indicated, all numbers expressing quantities of ingredients,
reaction conditions, and so forth used in the specification and claims are to
be
understood as being modified in all instances by the term "about."
Accordingly, unless
indicated to the contrary, the numerical parameters set forth in this
specification and
attached claims are approximations that may vary depending upon the desired
properties
sought to be obtained by the present invention.
What is claimed is:
