U.S. patent application number 12/192522 was filed with the patent office on 2009-07-02 for expansion agents for paper-based materials.
This patent application is currently assigned to NanoPaper, LLC. Invention is credited to Michael C. Berg, Toshiaki Hino, Gangadar Jogikalmath, William A. Mowers, Lynn Reis, David S. Soane.
Application Number | 20090165976 12/192522 |
Document ID | / |
Family ID | 40796673 |
Filed Date | 2009-07-02 |
United States Patent
Application |
20090165976 |
Kind Code |
A1 |
Soane; David S. ; et
al. |
July 2, 2009 |
EXPANSION AGENTS FOR PAPER-BASED MATERIALS
Abstract
Compositions and methods of producing paper-based materials are
disclosed. The techniques can utilize an amine-containing polymer,
such as chitosan, to functionalize one or more components of a
mixture used to form materials such as paper-based materials. Such
components can include the fibers of a pulp and/or filler
particles. Techniques and compositions are also described to
further improve the qualities of a paper material by utilizing a
complementary polymer which can couple with the amine-containing
polymer. Other compositions and methods are directed to forming
paper-based materials that are expandable.
Inventors: |
Soane; David S.; (Chestnut
Hill, MA) ; Berg; Michael C.; (Somerville, MA)
; Mowers; William A.; (Lynn, MA) ; Reis; Lynn;
(Somerville, MA) ; Jogikalmath; Gangadar;
(Cambridge, MA) ; Hino; Toshiaki; (Cambridge,
MA) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
WORLD TRADE CENTER WEST, 155 SEAPORT BOULEVARD
BOSTON
MA
02210-2604
US
|
Assignee: |
NanoPaper, LLC
Cambridge
MA
|
Family ID: |
40796673 |
Appl. No.: |
12/192522 |
Filed: |
August 15, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12184308 |
Aug 1, 2008 |
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12192522 |
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PCT/US07/03159 |
Feb 5, 2007 |
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12184308 |
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60765119 |
Feb 3, 2006 |
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60864783 |
Nov 7, 2006 |
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Current U.S.
Class: |
162/164.6 ;
162/158; 162/164.1; 162/175 |
Current CPC
Class: |
C08J 2301/00 20130101;
D21H 17/20 20130101; D21H 17/56 20130101; C08J 9/32 20130101; D21H
21/14 20130101; D21H 21/22 20130101; D21H 17/67 20130101; C08J
2203/22 20130101 |
Class at
Publication: |
162/164.6 ;
162/158; 162/164.1; 162/175 |
International
Class: |
D21H 17/56 20060101
D21H017/56; D21H 21/22 20060101 D21H021/22; D21H 17/20 20060101
D21H017/20; D21H 17/24 20060101 D21H017/24 |
Claims
1. An expandable paper product, comprising: paper pulp comprising
fibers; a plurality of expansion particles configured to increase
the volume of the expanded paper product; and a plurality of linker
agents configured to be attached to the plurality of expansion
particles, and to interact with the fibers to increase retention of
the plurality of expansion particles in the expanded paper
product.
2. The expandable paper product of claim 1, wherein the expansion
particles comprise at least one of blowing agents, encapsulated
propellants, and elastomer-based particles.
3. The expandable paper product of claim 2, wherein the expansion
particles are encapsulated propellants, the encapsulated
propellants comprising a polymeric shell encapsulating an
expandable material.
4. The expandable paper product of claim 1, wherein the expansion
particles comprise hydrophobic particles.
5. The expandable paper product of claim 1, wherein the plurality
of linker agents impart a net positive charge to a surface of the
plurality of expansion particles.
6. The expandable paper product of claim 1, wherein the fibers
exhibit a net negative charge.
7. The expandable paper product of claim 1, wherein the plurality
of linker agents comprise at least one of a coupling agent, a
crosslinking agent, and a polymer.
8. The expandable paper product of claim 7, wherein the plurality
of linker agents are polymers, the polymers comprising at least one
of a cationic polymer, a polymer exhibiting lower critical solution
temperature behavior, a pH sensitive polymer, and an amphiphilic
polymer.
9. The expandable paper product of claim 8, wherein the polymers
are amine-containing polymers.
10. The expandable paper product of claim 9, wherein the
amine-containing polymers comprise at least one of polyetheramine,
chitosan, polyvinyl amine, polyalkyleneimine, polyallyl amine, and
polydiallyl amine.
11. The expandable paper product of claim 7, wherein the
crosslinking agent comprises functional groups, the functional
groups comprising at least one of an aldehyde, an isocyanate, and
an epoxide.
12. The expandable paper product of claim 7, wherein the coupling
agent is a multifunctional silane coupling agent.
13. The expandable paper product of claim 1, wherein the plurality
of linker agents are covalently attached to the plurality of
expansion particles.
14. The expandable paper product of claim 1, wherein the plurality
of linker agents are non-covalently attached to the plurality of
expansion particles.
15. A method for producing an expandable paper product, comprising:
using a linker agent to attach expansion particles to fibers of a
paper pulp to thereby increasing retention of the expansion
particles; and activating the expansion particles to produce the
expandable paper product.
16. The method of claim 15, wherein the step of activating the
expansion particles comprises elevating the temperature of the
expansion particles to cause an increase in volume in the
expandable paper product.
17. The method of claim 15, wherein the step of using the linker
agent comprises using the linker agent to impart a net positive
charge to a surface of at least a portion of the expansion
particles.
18. The method of claim 17, wherein the at least a portion of the
expansion particles are attracted to a net negatively charged fiber
in the paper pulp.
19. The method of claim 15, wherein the step of using the linker
agent comprises: introducing hydroxyl groups on a surface of the
expansion particles; and exposing the expansion particles to a
silane-containing fluid, the silane-containing fluid attaching to
at least a portion of the hydroxyl groups.
20. The method of claim 15, wherein the step of using the linker
agent comprises: providing a polymer exhibiting a lower critical
solution temperature as the linker agent; and contacting the
expansion particles with the polymer at a high enough temperature
to cause precipitation of the polymer onto a surface of the
expansion particles.
21. The method of claim 15, wherein the step of using the linker
agent comprises: contacting the expansion particles with a polymer
at a high enough pH to cause precipitation of the polymer onto a
surface of the expansion particles.
22. The method of claim 15, wherein the step of using the linker
agent comprises: crosslinking the expansion particles with the
fibers of the paper pulp.
23. The method of claim 15, wherein the step of using the linker
agent comprises: at least one of covalently attaching and
non-covalently attaching the expansion particles to the linker
agent.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part
application that claims the benefit of a U.S. patent application
bearing Ser. No. 12/184,308, filed Aug. 1, 2008, entitled
"Functionalization of Paper Components;" which is a continuation of
PCT Application No. PCT/US07/03159, filed Feb. 5, 2007; which
claims the benefit of a U.S. Provisional Patent Application filed
on Feb. 3, 2006 and bearing serial number 60/765,119, and also
claims the benefit of another U.S. Provisional Patent Application
filed on Nov. 7, 2006 and bearing Ser. No. 60/864,783. All
applications are hereby incorporated by reference herein in their
entirety.
FIELD OF THE APPLICATION
[0002] The technical field of the present application relates to
compositions and methods for enhancing the properties of materials
such as paper-related products.
BACKGROUND
[0003] Paper manufacturing is an important industrial process,
resulting in the production of a vast variety of products. Paper
products oftentimes include the use of filler materials, which
allow products to be produced more cheaply. The use of fillers,
however, can decrease the quality of the product in terms of
strength, appearance, and other features. Though additives have
been derived for further improving the quality of manufactured
paper, a need persists for processes and compositions that further
improve the quality of paper. Indeed, the development of additives
which result in improved efficiency and lower cost production is
desirable.
SUMMARY
[0004] Some embodiments are directed to expandable paper products.
The product can include paper pulp having fibers, which can
optionally bear a net negative charge. The expandable paper product
can also include expansion particles, which can be configured to
increase the volume of the product. Linker agents can be configured
to be attached to the expansion particles, which can interact with
the fibers to increase retention of expansion particles in the
expanded paper product. Linker agents can be covalently, or
non-covalently, attached to one or more expansion particles.
[0005] Examples of expansion particles can include one or more of
blowing agents, encapsulated propellants, and elastomer-based
particles. Encapsulated propellants can include a polymeric shell
encapsulating an expandable material. Expansion particles can also
be embodied by particles that exhibit hydrophobicity.
[0006] Linker agents can be configured to impart a net positive
charge to a surface of the plurality of expansion particles. Linker
agents can include any combination of entities such as a coupling
agent, a crosslinking agent, and a polymer. In some instances, a
multifunctional silane coupling agent can be used as a linker
agent. Crosslinking agents, which can covalently link an expansion
particle with a pulp fiber, can include any combination of
functional groups such as an aldehyde, an isocyanate, and an
epoxide. Polymeric linker agents can include any combination of a
cationic polymer, a polymer exhibiting lower critical solution
temperature behavior, a pH sensitive polymer, and an amphiphilic
polymer. Amine-containing polymers, such as polyetheramine,
chitosan, polyvinyl amine, polyalkyleneimine, polyallyl amine, and
polydiallyl amine, can be used as linker agents.
[0007] Other embodiments are directed to methods for producing an
expandable paper product. A linker agent can be used to attach
expansion particles to fibers of a paper pulp, which can act to
increase retention of the expansion particles. The linker agent can
be covalently or non-covalently attached. Linker agents can be used
to impart a net positive charge to a surface of at least some of
the expansion particles, which can be attracted to a net negatively
charged fiber in the paper pulp. The expansion particles can be
activated, either before or after the linker agent is attached to
the particles and/or inserted into a paper making formulation, to
produce the expandable paper product. Activation can be embodiment
by elevating the temperature of the expansion particles to cause an
increase in volume in the expandable paper product.
[0008] In some instances, hydroxyl groups can be introduced on a
surface of the expansion particles. The expansion particles can be
exposed to a silane-containing fluid (e.g., gas and/or liquid),
which can result in at least a portion of the silane-containing
fluid attaching to at least some of the hydroxyl groups. In other
instances, a polymer can be provided to act as a linker agent,
which can exhibit a lower critical solution temperature. The
expansion particles can be contacted with the polymer at a
sufficiently high temperature to cause precipitation of the polymer
onto the surface at least some of the expansion particles. In
another instance, the expansion particles can be contacted with a
polymer (e.g., chitosan or some other amine-containing polymer) at
a sufficiently high pH to cause precipitation of the polymer onto a
surface of at least some expansion particles. The expansion
particles can also be crosslinked with the fibers of the paper
pulp.
DETAILED DESCRIPTION
[0009] As utilized in the present application, the term
"functionalization" and "functionalize" refer to a change in one or
more aspects of the physicochemical nature of an entity. For
example, with respect to a particle, functionalization of a
particle surface refers to a change in one or more aspects of the
particle surface, which result in some physicochemical change in
how the particle surface interacts with other entities. Consistent
with some embodiments described herein, functionalization of an
entity can result in a change in some macroscopic property (e.g.,
tensile strength) when the functionalized entity is used to produce
a product due to the associations of the functionalized entity with
other components, or even with other functionalized entities.
Functionalization can also alter the types of chemical reactions
that an entity can be subjected to relative to when the entity is
not functionalized.
[0010] The term "polymer" refers to a molecule comprising a
plurality of repeat units or monomers. A polymer can comprise one
or more distinct repeat units. For example, a "copolymer" refers to
a polymer having two or more distinct repeat units. Repeat units
can be arranged in a variety of manners. For example, a homopolymer
refers to a polymer with one type of repeat unit where the repeat
units are adjacently connected. In another example, a plurality of
different repeat units can be assembled as a copolymer. If A
represents one repeat unit and B represents another repeat unit,
copolymers can be represented as blocks of joined units (e.g.,
A-A-A-A-A-A . . . B-B-B-B-B-B . . . ) or interstitially spaced
units (e.g., A-B-A-B-A-B . . . or A-A-B-A-A-B-A-A-B . . . ), or
randomly arranged units. Of course, these representations can be
made with 3 or more types of repeat units as well. In general,
polymers (e.g., homopolymers or copolymers) include macromolecules
in a broad range of configurations (e.g., cross-linked, linear,
and/or branched).
[0011] The term "segments," and the phrase "polymer segments,"
which can be used interchangeably, refer to a portion of a polymer
that includes one or more units. A segment can include one or more
types of units (e.g., A-A-A-A or A-B-C-A-C).
[0012] Some embodiments are directed to compositions and methods
for producing materials such as paper-based materials. Such
embodiments can utilize an amine-containing polymer, which can be a
polycation. The amine-containing polymer can associate with one or
more components of a mixture (e.g., a paper-making mixture).
Components can include pulp fibers, the surfaces of a particle
filler, and other elements or portions of the elements. In general,
the association of the amine-containing polymer with any particular
component can functionalize that component, potentially increasing
the strength, or improving one or more other qualities, of a paper
product produced with compositions consistent with such
embodiments.
[0013] Accordingly, some exemplary embodiments are directed to
mixtures that can be used to produce various materials, such as
paper-based materials. Though such mixtures can include any number
of typical components utilized in commercial paper making, some
embodiments include a solution medium (e.g., an aqueous solution),
a pulp material, and filler particles. The mixtures can include an
amine-containing polymer, which can associate and/or interact with
one or more components of the mixture. For example, the
amine-containing polymer can functionalize the component of the
mixture with which the polymer interacts. In one aspect, the
amine-containing polymer can functionalize the particle filler
component (e.g., the surface of the filler particles), but does not
substantially functionalize the pulp. In another aspect, the
amine-containing polymer can functionalize the pulp (e.g., the
fibers of the pulp), but does not substantially functionalize the
filler component. In still another aspect, the amine-containing
polymer functionalizes both the filler component and the pulp.
Functionalization can and cannot also optionally occur with other
components in a selective manner.
[0014] Functionalization of one or more components of a
paper-making mixture with an amine-containing polymer can result in
the enhancement of one or more properties of the mixture or a paper
product formed from the mixture, relative to the properties when
functionalization of the component is absent. For instance,
functionalization of one or more components can lead to an
enhancement of mechanical properties of a paper product, e.g.,
tensile strength.
[0015] With respect to the pulp and the filler particles in a
mixture, though some embodiments can utilize functionalization of
both components, some particular embodiments only functionalize one
of the two components, while leaving the other component
substantially unfunctionalized, i.e., either the pulp or the filler
particles are functionalized, not both. It has surprisingly been
found that in some instances, only functionalizing the pulp or the
filler particles, but not both components, can lead to paper
products that are stronger, or about as strong, relative to both
components being functionalized.
[0016] The following text describes some features of the components
of mixtures consistent with embodiments of the present invention.
Unless specifically delineated in particular embodiments, it is
understood that one or more of the described features, or specific
components, can be utilized with any of the embodiments within the
scope of the present application. For instance, any of the specific
types of amine-containing polymers can be used in any mixture type
(e.g. chitosan or polyalkyleneimines or a combination of the two
can be used to functionalize any one or more of pulp, filler
particles, and other components of a mixture). It is also
understood that features of components can be utilized any
combination with the embodiments consistent herein. For instance,
in describing the average molecular weight of an amine-containing
polymer, it is understood that such average molecular weights can
be applied to any described polymer (e.g., homopolymers or
copolymers of any particular type of polymer such as branched
polyethyleneimine or polyvinylamine). It is further understood that
those skilled in the art will appreciate variations and
combinations of the described features that are also within the
scope of the present disclosure.
[0017] With respect to various embodiments disclosed herein, an
amine-containing polymer can be any homopolymer or copolymer that
has at least a portion of its repeat units containing an amine
(e.g., quaternary, ternary, secondary or primary). Advantageously,
the amine-containing polymer can contain repeat units with primary
amines due to the reactivity of the primary amine. In particular
embodiments, the amine-containing polymer is a polycation.
Polycations can be advantageously utilized, for example, when the
components sought to be functionalized have a net negative charge.
In such instances, the use of electrostatic interactions with pulp
fibers and/or filler can be effective in certain embodiments when
the pulp fibers and/or filler have an inherent negative charge that
can interact with the polycation.
[0018] A variety of amine-containing polymers can be utilized with
various embodiments that include one or more different types of
amine-containing polymers. Amine-containing polymers can be
naturally occurring macromolecules with amine groups such as
chitosan. Also, various types of synthetic polymers bearing amine
groups such as polyalkyleneimines, polyvinylamine, polyallylamine,
and polydiallylamine can be utilized. Of course, copolymers
comprising any combination of amine-containing homopolymer units
can also be used.
[0019] In some instances, it can be advantageous to utilize
amine-containing polymers that are relatively inexpensive because
of the scale and relative costs of paper manufacturing. Chitosan is
an aminopolysaccharide typically prepared by deacetylation of
chitin (poly-beta(1,4)-N-acetyl-D-glucosamine) obtained from marine
organisms such as shrimp, crabs, lobsters, squid, and the like.
Accordingly, it can be prepared with relative ease. Branched
polyethyleneimine (herein "BPEI") is an easily manufactured
synthetic polymer that is also readily available at moderate cost.
Thus, some embodiments utilize chitosan, polyethyleneimine (such as
BPEI), or a combination of the two polymers as separate
homopolymers or as one or more copolymers. Though many specific
instances herein discuss the use of chitosan with particular
embodiments and examples, it is understood that such descriptions
are merely demonstrative of features of the present invention, and
not intended to limit the practice of the present invention.
[0020] Though the average molecular weight of an amine-containing
polymer is not necessarily limited, in some embodiments the average
molecular weight of the amine-containing polymer can range from
about 1,000 daltons to about 10,000,000 daltons; or from about
10,000 daltons to about 500,000 daltons. Such ranges can
advantageously utilize amine-containing polymers which can be large
enough to functionalize one or more components effectively, while
not being so large as to effect the paper-making process.
[0021] Measurement of the average molecular weights for any polymer
discussed herein can be with respect to a number of bases. For
example, can be number averaged, weight averaged, or averaged based
on some other weighting factors. As well, the techniques utilized
to determine molecular weight can include the range of those known
to those skilled in the art. Examples include gel permeation
chromatography and light-scattering.
[0022] For certain amine-containing polymers, the average molecular
weight can be difficult to ascertain. Chitosan is an example of
such an amine-containing polymer. In such instances, the average
molecular weight of the polymer can be defined by some alternative
parameter such as viscosity. Accordingly, in some embodiments the
chitosan has an average molecular weight defined by a viscosity
range between about 10 centipoise and about 800 centipoise. The
viscosity can optionally be further defined by a set of conditions,
such as being measured for a 1% solution of chitosan in pH 4 (or
0.1M) aqueous acetic acid at 25.degree. C.
[0023] The pulp utilized in some embodiments disclosed herein can
comprise fibers such as cellulose-based fibers, and can also
include components typically found in pulps used to make paper
products. Accordingly, the fibers of the pulp can have a net
negative charge. Such charge can be utilized advantageously in some
embodiments to cause electrostatic attraction of an
amine-containing polymer that is, or is partially, a polycation. In
some embodiments, the fibers of a pulp exclude the presence of
synthetic fibers such as polymer-based fibers (e.g., aromatic amide
fibers). Thus, some embodiments utilize pulps that include
substantially naturally-occurring fibers.
[0024] Fillers utilized in some embodiments disclosed here can
include particulates that are typically utilized as fillers in
paper manufacturing applications. For instance, the fillers can
have a surface that is, at least partially, substantially inorganic
in nature. Thus, non-limiting examples of filler particles can
include particles constructed from calcium, carbonate, kaolin,
titanium dioxide, and other inorganic materials. Fillers can also
be a composite of inorganics. In some embodiments, the surface of
the fillers can have a net negative charge, which can tend to
attract amine-containing polymers that are polycationic in
nature.
[0025] In some embodiments, functionalization of one or more
components (e.g., pulp and/or filler) can be achieved by some type
of coupling interaction between an amine-containing polymer and the
component. Such coupling can be achieved using either through a
coupling agent or through electrostatic interactions that permit
the polyamine to self-assemble onto the surface of the component.
The use of electrostatic interactions with pulp fibers and filler
can be effective in certain embodiments because both pulp fibers
and filler have an inherent negative charge that can interact with
the polyamine. Coupling agents, such as multifunctional
crosslinking agents described herein, can be used to increase the
amount of amine-containing polymer that can adhere to a surface,
such as a surface of the filler particles.
[0026] For the compositions and methods disclosed herein,
multifunctional crosslinking agents can be used as a coupling
agent. Such agents can react with at least one of the
amine-containing polymer and the component to be coupled. For
example, in some embodiments the multifunctional coupling agent can
include a silicon containing coupling agent and at least one of the
following functional groups: an epoxy group, a hydroxyl group, a
carboxyl group, and/or an isocyano group. In one embodiment, the
multifunctional coupling agent is a silane coupling agent. In
another embodiment, the coupling agent does not include silicon
(e.g., in embodiments in which silicon is not used). In certain
embodiments, the multifunctional coupling agent includes an
isocyanosilane, for example, a trialkoxy isocyanosilane such as
trimethoxy isocyanosilane, triethoxy isocyanosilane, and/or
triisopropoxy isocyanosilane. In certain embodiments, the
multifunctional coupling agent includes an epoxy siloxane. The
multifunctional coupling agent can include triethoxy
methacryloxypropyl silane. Other agents can also be employed as
would be understood by those of skilled in the art.
[0027] In some embodiments, functionalization of a paper making
component can be achieved without the use of a coupling agent. For
instance, the amine-containing polymer can be added directly to a
pulp stream, a filler stream, or to both, resulting in the
association of the amine-containing polymer and the pulp, filler,
or both. If chitosan is used as the amine-containing polymer, the
component can be functionalized by precipitating chitosan onto the
surface of the component using, for example, a shift in pH. Since
chitosan is only soluble in acidic conditions, the polymer can be
made to precipitate when the pH is raised by adding a base to the
solution after adding chitosan (e.g., to a pH of at least about 6).
Accordingly, it can be advantageous to prepare mixtures of one or
more components (e.g., one or more of fillers and pulp) with
chitosan having a pH close to the precipitation point of the
amine-containing polymer to reduce the amount of base needed to
induce precipitation and functionalize the component. Thus, the pH
of the mixture can be in the range from about 4 to about 8; or from
about 5 to about 8; or from about 6 to about 8. In some instances,
it can be advantageous to utilize a multivalent acid to enhance the
dissolution of chitosan into a pulp furnish or other paper-making
mixture. Accordingly, some embodiments can utilize a mixture with
one or more multivalent acids; non-limiting examples include
citric, tartaric, aldaric (any in the family), oxalic, malonic,
malic, succinic, glutaric, and adipic acid.
[0028] Alternatively, precipitation can occur spontaneously when a
chitosan solution is added to a basic environment like a calcium
carbonate solution. In some embodiments, the amount of chitosan to
be added can be from about 0.01% to about 5.0% (based on weight of
the component), or from about 0.1% to about 2%.
[0029] In some embodiments, a complementary polymer can be added to
a paper-making mixture. In general, the complementary polymer can
be capable of coupling with an amine-containing polymer (e.g., the
complementary polymer can react or nonreactively interact with the
amine-containing polymer). Such a complementary polymer can be used
to enhance the properties of the mixture, or a resulting paper
product produced from the mixture, relative to not using the
complementary polymer. The complementary polymer can be utilized
when an amine-containing polymer is intended to functionalize pulp
(e.g., fibers), filler particles, or both pulp and filler
particles, among other paper-making mixture components.
[0030] In a mixture, the complementary polymer can be coupled with
the amine-containing polymer, or can be free but will eventually
couple with the amine-containing polymer. As well, the
complementary polymer can be added to a process after an
amine-containing polymer has functionalized one or more mixture
components, or before functionalization has occurred such as in an
emulsion technique described herein.
[0031] Some embodiments can utilize any complementary polymer
(e.g., homopolymers, copolymers, and combinations of different
polymers) which can interact nonreactively with an amine-containing
polymer or which can react with the amine-containing polymer (e.g.,
reacting with an amine group). If the complementary polymer
nonreactively interacts rather than reacts with the
amine-containing polymer, the interaction may involve electrostatic
forces, hydrogen bonds, or any other secondary interaction forces
or association mechanisms. For example, the nonreactive interaction
can be an electrostatic interaction when a polyanion is used as a
portion or the entirety of the complementary polymer. Accordingly,
an appropriate polymer can also be used that includes repeat units
with anionic charge. Advantageously, the polyanion can include one
or more carboxylic acid groups. Non-limiting examples of suitable
polyanions, or polyanion segments, include biopolymers such as
pectin, xanthum gum, and carboxymethyl cellulose, and synthetic
polymers such as polyacrylic acid or polymethacrylic acid. Other
types of complementary polymers, such as polyanions or polymers
with polyanionic segments, can also be used consistent with the
embodiments disclosed herein.
[0032] In embodiments when the complementary polymer can react with
the amine-containing polymer, the complementary polymer can contain
repeat units that include one or more groups which can react with a
portion of the amine containing-polymer. In particular embodiments,
the groups can be selected to react with an amine functionality
(primary, secondary, ternary, or quaternary). Such groups include
but are not limited to epoxides, anhydrides (e.g., maleic
anhydride), carboxylic acids, and isocyanates. When copolymers are
utilized as a complementary polymer, such copolymers can also
contain some repeat units with these reactive groups. The molecular
weight of the complementary polymer can be between about 1,000
daltons and about 10,000,000 daltons; or between about 10,000
daltons and about 500,000 daltons.
[0033] As previously mentioned, a complementary polymer can be used
to enhance the properties of a mixture, or a resulting paper
product produced from the mixture. For example, the complementary
polymer can be used to provide additional strength to a resulting
paper-based product, whether an amine-containing polymer is used to
functionalize pulp, filler particles, or both pulp and filler.
Without being bound by theory, it is believed that the
complementary polymer can act to bridge components that have been
functionalized with the amine-containing polymer. As an example, if
only the pulp fibers are functionalized, the polymer bridges
different fibers. However, if both the pulp and filler have been
functionalized, the filler can also be bound to the pulp for
enhancing mechanical properties of the paper making mixture or a
resulting paper product.
[0034] In some embodiments, the complementary polymer can contain
one or more components that can impart additional or alternative
properties to a resulting paper product besides strength
enhancement. As an example, elastic homopolymers or copolymers can
be used to change the resulting paper's stiffness or wear
resistance, or hydrophobic homopolymers or copolymers can be used
to change the water contact angle (e.g., the tendency to resist
water penetration). Combinations of various types of complementary
polymers can also be used to provide multiple property enhancement
(e.g., strength, elasticity, and water resistance).
[0035] In other embodiments, the complementary polymer can be
emulsified by the amine-containing polymer. This combination can be
mixed with a portion of a pulp furnish, i.e., delivered in one
addition versus in sequential steps. In this case, one or a
combination of the type of amine-containing polymers discussed
previously can be used, along with one or more complementary
polymers which are not soluble in water. The complementary polymer
can interact nonreactively or react with the amine-containing
polymer. Besides being substantially hydrophobic, the complementary
polymer can have any of the properties previously disclosed herein.
The complementary polymer can either be emulsified using the
amine-containing polymer alone (e.g., if it is in liquid form) or
dissolved in a water immiscible solvent to form a "water-in-oil"
emulsion. This emulsion can then be added to either the fiber
and/or filler stream so that the amine-containing polymer can
interact with the filler and/or fiber. For example, upon drying,
the miscelle can open up to allow the emulsified polymer to
interact or bind between multiple fillers and/or fibers.
[0036] Some exemplary embodiments are drawn to methods of producing
materials such as paper-based materials, which are optionally
consistent with one or more of the compositions disclosed herein.
One exemplary method includes functionalizing fibers of a pulp
using an amine-containing polymer. Filler particles can be combined
with the functionalized pulp fibers to produce at least a portion
of a paper-forming mixture such as a pulp furnish. A paper-based
material can then be produced from the paper-forming mixture. In
some instances, it can be advantageous for the method not to
substantially functionalize the filler particles, though the pulp
components can be functionalized. The method can be practiced as a
batch process or in continuous fashion using flowing streams of
components.
[0037] In alternative embodiments, the methods of producing
materials functionalize filler particles (e.g., the surface of
filler particles) using the amine-containing polymer. Fibers of a
pulp can be combined with the functionalized filler particles to
produce a portion or the entirety of a paper-making mixture, which
can be subsequently used to produce a paper-based material. In this
embodiment, it can be advantageous in some instances to not
substantially functionalize the fibers of the pulp. In still other
embodiments, both the pulp and the filler particles can be
functionalized.
[0038] The types of amine-containing polymers, filler particles,
and pulps that can be used with these methods include all the types
disclosed in the present application. As well, specific techniques
for functionalizing the pulp, filler particle, or both pulp and
filler particles can follow the techniques disclosed herein (e.g.,
addition of coupling agents to aid coupling of an amine-containing
polymer to a component). In one particular example, chitosan can be
combined with either pulp or filler particles to form a
functionalizing mixture. The pH of the mixture can be raised to a
level of at least about 6 to cause the chitosan to associate with
the pulp fibers or filler particles, thereby functionalizing the
component. It is also understood that paper-forming mixtures
utilized in the various methods can include any of the other
components of mixtures disclosed herein (e.g., complementary
polymers).
[0039] The step of producing a paper-based material from the
paper-forming mixture can utilize any set of paper forming
techniques including those known to ones skilled in the art. For
example, the paper-forming mixture can be set on a screen to form a
sheet. The sheet can be subsequently dried to form the paper
product. Modifications of this technique and others to accommodate
embodiments disclosed herein are also contemplated by the present
application.
[0040] For example, in methods that utilize a complementary
polymer, the complementary polymer can be added to a paper-making
mixture before a sheet is formed from the mixture, or after the
sheet has been formed (e.g., applied onto the sheet). When the
complementary polymer is added to the process before sheet
formation, it can be of sufficient quantity to produce a desired
enhancement in some property (e.g., mechanical properties of the
end paper product), but not enough to cause problems with sheet
formation. In some embodiments, this addition level can be from
about 0.01% to about 5.0% (based on sheet dry weight), or between
about 0. 1% and about 2%.
[0041] When the complementary polymer is added after sheet
formation, it can be added prior to drying the sheet (e.g., while
the sheet is still on the paper machine), or it may be added after
drying the sheet (e.g., in a coating or other dry end process). The
polymer can be added in solution form which can either be aqueous
or non-aqueous. Aqueous solutions can be used when addition is done
prior to drying the sheet, but non-aqueous solutions can be
advantageous after drying due to energy usage in eliminating the
solvent. When the complementary polymer is reactive, the reaction
can occur anytime in the process after introduction of the
complementary polymer, i.e., the reaction between the complementary
polymer and the amine-containing polymer can occur either
immediately after addition or anytime thereafter.
[0042] In alternative embodiments connected with the use of a
complementary polymer, the methods described herein can include
emulsifying a complementary polymer (e.g., a substantially
hydrophobic polymer) with the amine-containing polymer in an
aqueous solution. The emulsion formed from the complementary
polymer and amine-containing polymer can be added to the pulp
fibers, the filler particles, or both to cause the amine-containing
polymer to functionalize one or more components. In instances where
both pulp fibers and filler particles are functionalized, the
amine-containing polymer can couple a portion of the pulp and a
portion of the filler particles.
[0043] Some embodiments are directed to compositions and methods
for forming paper-based materials that are expandable such as
paper-based materials that exhibit high bending stiffness. High
bending stiffness is desirable in many paper and paperboard
applications. Bending stiffness relates to the amount of force
required to bend a paper product through a designated angle.
Stiffness can be important for packaging materials, box boards,
corrugated paper products, and the like. At the same time, it is
desirable that packaging materials, while stiff, be lightweight and
economically produced.
[0044] The use of expansion agents in a paper pulp formulation can
create an expandable paper material (e.g., high bending stiffness
material) by creating void spaces in a paper product upon
activation. These agents, however, are often hydrophobic in nature,
and usually lack the surface functionalities necessary to attach
themselves to the pulp fibers during the papermaking process. Their
hydrophobicity also makes their dispersion in aqueous slurries
difficult and thereby reduces the effectiveness of use of such
agents in papermaking.
[0045] Accordingly, some embodiments are drawn to techniques and
compositions involving expandable paper products that incorporate
the use of linker agents. The linker agents can be configured to be
attached to expansion particles, which can be activated to increase
the volume of the expandable paper product. The linker agents can
also interact with the fibers of a paper pulp to increase retention
of the expansion particles, relative to not using a linker agent,
during the paper making process. Any of the paper pulps, and
associated fibers, disclosed in the present application can be
utilized with the expandable paper product embodiments described
herein.
[0046] The term "attach" refers to a coupling between entities.
Such coupling can either be direct, such as a polymer sharing a
covalent chemical bond with a surface site of a particle together,
or can be indirect, such as coupling a polymer and a surface site
together using an intermediary agent which is directly coupled to
the polymer and the surface site (e.g., a bifunctional coupling
agent). Attachment between entities can occur by any feasible
mechanism consistent with an embodiment of the invention.
Accordingly, non-limiting mechanisms by which chemical entities can
be bound together include covalent bonding, non-covalent bonding,
electrostatic (or ionic) forces, Van der Waals forces, hydrogen
bonding, other intermolecular forces, and combinations of the
listed mechanisms.
[0047] Some embodiments utilize linker agents that are covalently
attached to the expansion particles, while other embodiments
utilize linker agents that are not covalently attached to the
expansion particles.
[0048] Since many expansion particles are hydrophobic in nature,
the particles often do not inherently possess surface
functionalities readily available for chemical modification.
Accordingly, linker agents can act to modify the surfaces of the
expansion particles, which can improve the particulate retention
and dispersion during the paper making process. For example, many
paper pulps are formed from fibers that carry a net negative
charge. Accordingly, some embodiments utilize linker agents capable
of imparting a net positive charge to the surfaces of the expansion
particles. The modified particles can then have some electrical
charge affinity for the fibers, and thus exhibit improved expansion
particle retention in the papermaking pulp and/or paper product. It
is understood, however, that linker agent affinity for a pulp fiber
can be through any type of molecular force, and is not limited to
electrostatic interactions. Indeed, in some embodiments, the linker
agent can be covalently bonded to a fiber and/or attracted by other
forces such as van der Waals, hydrogen bonding, polymer/fiber
entanglement and/or other molecular forces.
[0049] A variety of expansion particle types can be utilized with
the embodiments disclosed herein, including combinations of
different types of particles. Some non-limiting examples include
blowing agents, encapsulated propellants, and elastomer-based
particles. Activation of the expansion particle can be through any
suitable mechanism such as chemical reaction and/or exposure to a
selected temperature range. For example, an expansion particle can
be formed in a chemical reaction during the papermaking process to
provide the expanded qualities of the final product.
[0050] Blowing agents in the pre-blown state can be added into the
fiber slurry before a sheet of paper is formed. The blowing agents
can include any particles that release gas upon being exposed to a
sufficiently high temperature to cause void formation that result
in a foamed sheet being formed. Non-limiting examples of materials
that can act as blowing agents include structures that can comprise
sodium bicarbonate, azodicarbonamide-based blowing agents, and
p-p'-oxbis (benzensulfonlyhydrazide).
[0051] Encapsulated propellants can be made of polymeric materials,
which encapsulate a propellant (e.g., gas or liquid or other
expandable material). When heated to above its softening
temperature, the polymer shell softens and the gas/liquid or other
material contained within the shell expands thereby irreversibly
expanding the polymer shell. When such particles are incorporated
into paper making process, they can expand during the drying stage
of the papermaking, or later resulting in creation of void spaces
in the interior of the paper leading to increased stiffness while
reducing the basis weight of such a paper. Some potential
encapsulated propellants include styrene particles encapsulating
organic solvents such chlorinated hydrocarbons, toluene, etc.; or
particles made of styrene-maleic anhydride copolymers which trap
acetone within the particle's interior.
[0052] For compressible articles, expansion particles made with
elastomers can be effective as dampeners in sensitive packaging
applications. Elastomeric expandable particles can be prepared by a
mixture of polymers such as styrene and butadiene polymers, or
their copolymers. The elastomer component and thereby
compressibility of the particles could be controlled by the content
of the butadiene part. In another example, styrene maleic anhydride
could be mixed (in acetone) with isobutylene-maleic anhydride
copolymers in different ratios to change the elastomeric content of
the resulting particle. In such embodiments, the elastomeric
particles can regain their shape upon removal of force absorbing
shock imposed on the paperboard. Such expandable particles are
commercially available and can also be made in the laboratory using
a variety of polymers using spraying or spray drying equipment.
[0053] Linker agents for use with some embodiments include any
combination of materials capable of attaching with expansion
particles and interacting with the fibers of a paper pulp. Examples
of linker agents include coupling agents, crosslinking agents, and
a variety of polymers.
[0054] Coupling agents include multifunctional coupling agents such
as multifunctional silane coupling agents, and others as described
earlier in the present application. Application of the coupling
agents can be performed in a variety of manners. In some particular
embodiments, the expansion particles can be exposed to a
silane-containing fluid (e.g., vapors or a dilute solution) such as
aminopropyltrimethoxy silane. To enable silane attachment, hydroxyl
groups can be introduced on the surface of the expansion particles
using mild oxidizing agents, or corona treatment, or radio
frequency plasma treatment. Such silane modified particles would
then have amine functionality, and can associate with anionic pulp
fibers.
[0055] Crosslinking agents include entities capable of covalently
linking fibers with expansion particles. This can lead to stronger
retention of expansion particles in the paper and paperboard
articles, and can reduce the possibility of particles coming off
the paperboard and reducing its effectiveness. Potential
crosslinking agents include molecules with one or more suitable
functional groups such as aldehydes (e.g., glyoxal and
glutaraldehyde), epoxides, and isocyanates.
[0056] A variety of polymers can be used as linking agents. In many
embodiments, the polymers include polycations for imparting a net
positive charge to an expansion particle surface. In some
embodiments, the polycations are amine-containing polymers such as
chitosan and others as described within the present application.
Attachment of the polymers to an expansion particle (e.g., chitosan
to a blowing agent) can be provided through a variety of
mechanisms.
[0057] In some embodiments, linker agents are utilized that include
polymers that exhibit a lower critical solution temperature (herein
"LCST") phenomena. That is, the polymer tends to phase separate at
elevated temperatures. For instance, polymers such as
polyetheramines (e.g., Jeffamine compounds from Huntsman
Corporation, Woodlands, Tex.) can be used to modify surfaces of
expansion particles. Polyetheramines containing either
ethyleneoxide or propyleneoxide monomers exhibit LCST behavior. By
contacting expansion particles in mixtures containing
polyetheramines at temperatures below their LCST, and slowly
warming the solution to above LCST, the precipitation of the
polyetheramines onto the surfaces of particles is induced. This can
immobilize cationic groups (e.g., amines) on particle surfaces,
which can be useful in attractive association with anionic pulp
fibers.
[0058] In some embodiments, amphiphilic block copolymers can be
utilized as linker agents. The amphiphilic block copolymers can
have hydrophobic and hydrophilic polymer segments. The hydrophilic
segments can include cationic groups for potential interaction with
pulp fibers. The hydrophobic segments can interact with an
expansion particle surface, resulting in the attachment of the
block copolymer to the expansion particle. Accordingly, the
hydrophilic segments with cationic groups can act to impart a net
positive charge to the expansion particle surface.
[0059] In some embodiments, expansion particles are attached to
polymers having a pH sensitivity. For instance, chitosan solutions
are prepared by dissolving the chitosan polymer slowly in acidic
aqueous solution. Once soluble, chitosan can be precipitated out of
the solution by raising the pH of this solution using a base such
as NaOH. If there are particles present in the solution, the
precipitate will coat their surface resulting in amine
functionalized particles. Accordingly, expansion particles can be
mixed in an acidic chitosan solution. The pH of the solution can be
increased incrementally until chitosan is precipitated onto the
particles resulting in a surface coating of chitosan. The
precipitation can lead to high particle surface coverage with
chitosan. The amount of surface coverage by chitosan can be
controlled by varying the ratio of chitosan to particles in the
mixture.
[0060] In some embodiments, a mixture of different polymers can be
utilized. The polymers are preferably soluble in a common solvent
and can be deposited onto the surface of the expansion particles,
or can be formed into an expansion particle, with at least one of
the polymers acting as the linker agent. For instance, at least one
of the polymers can be present in higher proportion, which can form
the bulk of a particle shell. The minority polymer component can
have amine functionality, or other cationic functionality, either
in the backbone or as a side group. An example is chitosan. The
minority polymer component can become part of the shell of the
expansion particle and can act as a linker agent, providing
cationic surface functionality to enable attachment between the
particle and anionic surfaces such as pulp fibers.
[0061] In a particular embodiment, mixtures of polymers such as
styrene maleic anhydride (herein "SMA") and styrene maleimide
(herein "SMAI") copolymers can be used to create expansion
particles which have cationic maleimide functional groups from SMAI
on their surface. SMA and SMAI can be mixed together in common
solvents such as acetone or other expandable fluid. The mixture can
be spray dried to produce expansion particles encapsulating acetone
with maleimide surface functional groups. The density of maleimide
surface functionality and thereby the surface charge density can be
controlled by varying the amount of SMAI in the mixture.
[0062] In some embodiments, chitosan analogues polymers can be
utilized as linker agents. The chitosan analogues can be designed
by taking polymers with amine functionalities such as
polyvinylamine or polyallylamine or polyethyeleneimine and
modifying them with side groups that are hydrophobic in nature.
Examples of such side groups can include hydrocarbon-based chains
(e.g., linear or branched carbon/hydrogen molecules, either
aromatic or aliphatic, such as those having between 2 and 20
carbons in the backbone), which can be unsubstituted or substituted
with water-repellant functionalities such as fluoro functionalities
and/or heteroaromatics. The hydrophobic groups can render the water
soluble amine polymers less water soluble at selected pHs,
resulting in precipitation of the modified polymer. Such chitosan
analogues can be used to functionalize expansion particles to
increase their retention onto to negatively charged surfaces.
[0063] In other embodiments, side groups attached to an
amine-containing polymer can include polymer segments or monomers
exhibiting LCST behavior. Association and precipitation of the
amine-containing polymer with these side groups can be controlled
by temperature manipulation.
[0064] Other embodiments are drawn to paper-based materials that
can be produced from any of the mixtures or methods described in
the present application.
EXAMPLES
[0065] The following examples are provided to illustrate some
aspects of the present application. The examples, however, are not
intended to limit the scope of any embodiment of the invention.
Example 1
Control Pulp Synthesis
[0066] A 5% pulp slurry was prepared by blending 17.5 g of pine
furnish (dry weight) with 32.5 g of birch (dry weight) in 1 L of
water. This thick slurry was then diluted to 0.5% by adding 9.5 L
of water to the 1 L of thick stock slurry.
Example 2
Chitosan on Pulp (No Base Addition)
[0067] A 5% pulp slurry was prepared by blending 17.5 g of pine
furnish (dry weight) with 32.5 g of birch (dry weight) in 1 L of
water. This thick slurry was then diluted to 0.5% by adding 9.5 L
of water to the 1 L of thick stock slurry. To this 0.5% slurry,
12.5 mL of a 2.0% CG110 chitosan solution (Primex, Iceland) was
slowly added.
Example 3
Chitosan on Pulp (with Addition of NaOH)
[0068] A 5% pulp slurry was prepared by blending 17.5 g of pine
furnish (dry weight) with 32.5 g of birch (dry weight) in 1 L of
water. This thick slurry was then diluted to 0.5% by adding 9.5 L
of water to the 1 L of thick stock slurry. To this 0.5% slurry,
12.5 mL of a 2.0% CG110 chitosan solution was slowly added. A
solution of 0.1 M NaOH was then titrated into the pulp slurry until
the pH reached 8.0 (the original pH was approximately 6.5--example
2).
Example 4
Control Precipitated Calcium Carbonate (PCC)
[0069] A 10% PCC slurry was made by stirring 10 g of PCC into 1 L
of water.
Example 5
Chitosan Coated PCC
[0070] A 10% PCC slurry was made by stirring 10 g of PCC into 100
mL of water. To this slurry, 2.5 mL of a 2.0% CG110 chitosan
solution was slowly added. The high pH of the PCC solution caused
the chitosan to precipitate onto the PCC particles. This was
verified by taking a sample and attaching a reactive intense blue
dye that turned the PCC blue. The dye did not react with PCC that
was not functionalized with chitosan.
Example 6
Handsheet Preparation
[0071] Handsheets were prepared using a handsheet maker, model Mark
V Dynamic Handsheet Mold/Paper Chemistry Jar from Paper Chemistry
Laboratory Inc. (Larchmont, N.Y.). The appropriate volume of 0.5%
pulp slurry (functionalized or unfunctionalized) was combined with
the appropriate volume of the 10% filler slurry (functionalized or
unfunctionalized). This combined slurry was diluted with water up
to 2 L and added to the handsheet maker. The overhead stirrer was
then powered on and set to stir at 1100 RPM for 5 seconds, 700 RPM
for 5 seconds, 400 RPM for 5 seconds, and then raised out of the
slurry. The water was then drained off. The subsequent sheet was
then transferred off of the wire and pressed and dried. Each test
condition was repeated to make two handsheets for each trial point.
Three 1'' wide strips were then cut out from each handsheet for
tensile testing on an Instron Single Column Testing System Model
#3343 (Norwood, Mass.). The reported values are the averages of the
six strips (three from each handsheet).
Example 7
Control 100% Pulp
[0072] Two handsheets were produced using the above procedure. In
the process, 500 mL of pulp from example 1 was used along with no
filler. These were control sheets that had an average max
load/width of 9.9 lb/in. When normalized by the basis weight (i.e.,
the density of each sheet on a mass per unit area basis), the
result was 0.11 lb*m.sup.2/in/g.
Example 8
100% Pulp (w/Chitosan, no Base)
[0073] Two handsheets were produced using the above procedure. In
the process, 500 mL of pulp from example 2 was used with no filler.
These sheets that had an average max load/width of 10.1 lb/in. When
normalized by the basis weight, the result was 0.12
lb*m.sup.2/in/g.
Example 9
Control 90% Pulp/10% PCC
[0074] Two handsheets were produced using the above procedure. In
the process, 450 mL of pulp from example 1 was used along with 12.5
mL of filler from example 4. The retention of the filler from
example 4 with pulp from example 1 was previously tested to be
approximately 20%, so these handsheets would be approximately 10%
by weight PCC. These 90% fiber/10% PCC sheets had an average max
load/width of 5.9 lb/in. When normalized by the basis weight, the
result was 0.068 lb*m.sup.2/in/g.
Example 10
90% Pulp (with Chitosan, No Base)/10% PCC
[0075] Two handsheets were produced using the above procedure. In
the process, 450 mL of pulp from example 2 was used along with 3.0
mL of filler from example 4. The retention of the filler from
example 4 with pulp from example 2 was previously tested to be
approximately 83%, so these handsheets would be approximately 10%
by weight PCC. These 90% fiber/10% PCC sheets had an average max
load/width of 9.1 lb/in. When normalized by the basis weight, the
result was 0.095 lb*m.sup.2/in/g.
Example 11
90% Pulp (with Chitosan, NaOH added)/10% PCC
[0076] Two handsheets were produced using the above procedure. In
the process, 450 mL of pulp from example 3 was used along with 3.0
mL of filler from example 4. The retention of the filler from
example 4 with pulp from example 3 was previously tested to be
approximately 83%, so these handsheets would be approximately 10%
by weight PCC. These 90% fiber/10% PCC sheets had an average max
load/width of 10.1 lb/in. When normalized by the basis weight, the
result was 0.11 lb*m.sup.2/in/g,; a substantially similar result to
the control sample of 100% pulp.
Example 12
90% Pulp/10% PCC (with Chitosan)
[0077] Two handsheets were produced using the above procedure. In
the process, 450 mL of pulp from example 1 was used along with 2.5
mL of filler from example 5. The retention of the filler from
example 5 with pulp from example 1 was previously tested to be
approximately 99%, so these handsheets would be approximately 10%
by weight PCC. These 90% fiber/10% PCC sheets had an average max
load/width of 8.2 lb/in. When normalized by the basis weight, the
result was 0.087 lb*m.sup.2/in/g.
Example 13
90% Pulp (with Chitosan, NaOH added)/10% PCC (with Chitosan)
[0078] Two handsheets were produced using the above procedure. In
the process, 450 mL of pulp from example 3 was used along with 2.5
mL of filler from example 5. The retention of the filler from
example 5 with pulp from example 1 was previously tested to be
approximately 99%, so these handsheets would be approximately 10%
by weight PCC. These 90% fiber/10% PCC sheets had an average max
load/width of 7.2 lb/in. When normalized by the basis weight, the
result was 0.080 lb*m.sup.2/in/g. Accordingly, example 13 shows
that functionalizing the pulp and PCC with chitosan unexpectedly
results in a sheet that is less strong than just functionalizing
the pulp (example 11) or just functionalizing the PCC (example
12).
Example 14
Addition of a Complementary Polymer
[0079] Handsheets were created using the above procedures. After
drying the handsheet, approximately 6.5 mL of a 0.2% aqueous
poly[(isobutylene-alt-maleic acid), ammonium
salt)-co-(isobutylene-alt-maleic anhydride] solution was applied to
the handsheet. Each test condition was repeated to make two
handsheets for each trial point. Three 1'' wide strips were then
cut out of each handsheet for tensile testing on the Instron 3343.
The reported values are the averages of the six strips (three from
each handsheet).
Example 14a
Poly[(Isobutylene-Alt-Maleic Acid), Ammonium
Salt)-Co-(Isobutylene-Alt-Maleic Anhydride] added to 100% Pulp
[0080] Two handsheets were made using the procedure described in
example 7 (100% pulp). Then, the sheets were treated with the
Poly[(isobutylene-alt-maleic acid), ammonium
salt)-co-(isobutylene-alt-maleic anhydride] solution using the
above procedure. These sheets had an average max load/width of 13.2
lb/in. When normalized by the basis weight, the result was 0.14
lb*m.sup.2/in/g.
Example 14b
Poly[(Isobutylene-Alt-Maleic Acid), Ammonium
Salt)-Co-(Isobutylene-Alt-Maleic Anhydride] added to 100% Pulp with
Chitosan
[0081] Two handsheets were made using the procedure described in
example 8 (100% pulp with chitosan). Then, the sheets were treated
with the Poly[(isobutylene-alt-maleic acid), ammonium
salt)-co-(isobutylene-alt-maleic anhydride] solution using the
above procedure. These sheets had an average max load/width of 14.2
lb/in. When normalized by the basis weight, the result was 0.16
lb*m.sup.2/in/g.
[0082] In example 14a, the second polymer addition produced a sheet
approximately 35% stronger than the control sheet (example 7). In
example 14b, a sheet was produced that was approximately 50%
stronger than the sheet with chitosan on pulp (example 8).
Example 15
Preparation of Control Long Fiber Pulp
[0083] 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 16
Handsheet Preparation
[0084] Handsheets were prepared using a Mark V Dynamic Paper
Chemistry Jar and Hand-Sheet Mold from Paper Chemistry Laboratory,
Inc. (Larchmont, N.Y.). To form a handsheet, the appropriate volume
of a selected 0.5% pulp slurry prepared according to example 15 was
functionalized with up to 2% the of the appropriate polymer(s)
(based on dry weight), as disclosed in the Examples below. Polymer
additions were done at 10 minute intervals. The functionalized pulp
slurry was diluted with water up to 2 L and added to the handsheet
maker. The slurry was then mixed at a rate of 1100 RPM for 5
seconds, 700 RPM for 5 seconds, and 400 RPM for 5 seconds. The
water was removed from the slurry by draining to form the
handsheet. The handsheet was then transferred off of the wire,
pressed and dried.
Example 17
Control Handsheets
[0085] Handsheets were produced according to the method in example
16, using 400 ml of the material produced according to example 15.
There was some fluctuation of pulp concentration from run to run,
producing some slight variability in basis weights for these
samples. The final paper weight was approximately 2 g for the
control sheets. The maximum load/width for these sheets, when
subjected to the tensile test of example 6, ranged from 10.3
lb.sub.f/in to 11.4 lb.sub.f/in.
Example 18
Expandable Particles
[0086] Expandable particles were made with Styrene maleic anhydride
copolymers using a paint spray gun such as Preval. A 10% solution
of Styrene maleic anhydride in different styrene to maleic
anhydride ratios of 1:1, 2:1, 3:1, 4:1 were made in acetone. The
solution was sprayed onto a large enclosed chamber by using a
pressurized paint dispenser atomizer such as Preval (make). The
chamber was closed for 10 minutes and the particles were collected
from the bottom of the box and used for papermaking.
Example 19
Expandable Particles Coated with Chitosan
[0087] Handsheets were produced according to the method of example
16, using 400 ml of the pulp slurry from example 15 and 20% SMA
particles based on dry weight. A 2% chitosan solution was then
added to the pulp-starch slurry, with concentrations of chitosan
ranging from 0.5% to 8% of the final weight of the handsheet. As an
alternative, chitosan can be precipitated onto the expandable
particles by using NaOH to titrate the mixture of particles and
chitosan to a pH of 6.5 before adding the expandable particles to
the pulp slurry. Using varying concentrations of chitosan, the
retention of expandable particles in the pulp slurry can be
increased.
Example 20
Expandable Particles with Polyvinylamine
[0088] Handsheets were produced according to the method of example
16, using 400 ml of the pulp slurry from example 15 to which was
added various percentages of expandable particles based on dry
weight. A 2% polyvinylamine (PVAm) solution was then added to the
slurry, with concentrations of PVAm ranging from 0.5% to 8% of the
final weight of the handsheet.
Example 21
Expandable Particles with Poly Diallyldimethyl Ammonium Chloride
(DADMAC)
[0089] Handsheets were produced according to the method of example
16, using 400 ml of the pulp slurry from example 15 to which was
added varying amounts of expandable particles based on dry weight
of the pulp. DADMAC was then added to the expandable particles-pulp
slurry, with concentrations of DADMAC ranging from about 0.25% to
2% of the final paper weight.
Example 22
Preparation of Retention Aids
[0090] Polyvinylamine was 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.
Example 23
Characterization of Retention Aid
[0091] The modified polyvinylamine was dissolved in water and the
pH was incrementally lowered till the solution became cloudy. The
pH at which the polymer precipitated out of solution was
recorded.
Example 24
Elastomeric Expandable Fillers
[0092] Expandable elastomeric particles were made with isobutylene
maleic anhydride copolymers using a paint spray gun such as Preval.
A 10% solution of isobutylene maleic anhydride was made in acetone.
The solution was sprayed onto a large enclosed chamber by using a
pressurized paint dispenser atomizer such as Preval (make). The
chamber was closed for 10 minutes and the particles were collected
from the bottom of the box and coated with chitosan as in example
19.
EQUIVALENTS
[0093] While the present invention has been described in terms of
specific methods, structures, and compositions it is understood
that variations and modifications will occur to those skilled in
the art upon consideration of the present invention. For example,
the methods and compositions discussed herein can be utilized
beyond the preparation of the paper compositions in some
embodiments. As well, the features illustrated or described in
connection with one embodiment can be combined with the features of
other embodiments. Such modifications and variations are intended
to be included within the scope of the present invention. Those
skilled in the art will appreciate, or be able to ascertain using
no more than routine experimentation, further features and
advantages of the invention based on the above-described
embodiments. Accordingly, the invention is not to be limited by
what has been particularly shown and described, except as indicated
by the appended claims.
[0094] All publications and references are herein expressly
incorporated by reference in their entirety. The terms "a" and "an"
can be used interchangeably, and are equivalent to the phrase "one
or more" as utilized in the present application. The terms
"comprising," "having," "including," and "containing" are to be
construed as open-ended terms (i.e., meaning "including, but not
limited to,") unless otherwise noted. Recitation of ranges of
values herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
* * * * *