U.S. patent application number 15/370198 was filed with the patent office on 2017-03-23 for methods for increasing retention and drainage in papermaking processes.
This patent application is currently assigned to Ecolab USA Inc.. The applicant listed for this patent is Ecolab USA Inc.. Invention is credited to William J. Andrews, Brett Brotherson, Xiaojin Harry Li, Peter E. Reed, Mingli Wei.
Application Number | 20170081801 15/370198 |
Document ID | / |
Family ID | 51522183 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170081801 |
Kind Code |
A1 |
Brotherson; Brett ; et
al. |
March 23, 2017 |
Methods for Increasing Retention and Drainage in Papermaking
Processes
Abstract
Disclosed herein are methods of increasing retention and
drainage in papermaking processes using high molecular-weight,
water-soluble polymers.
Inventors: |
Brotherson; Brett; (Lisle,
IL) ; Reed; Peter E.; (Plainfield, IL) ; Li;
Xiaojin Harry; (Palatine, IL) ; Andrews; William
J.; (Parker, CO) ; Wei; Mingli; (Naperville,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ecolab USA Inc. |
Naperville |
IL |
US |
|
|
Assignee: |
Ecolab USA Inc.
Naperville
IL
|
Family ID: |
51522183 |
Appl. No.: |
15/370198 |
Filed: |
December 6, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14734609 |
Jun 9, 2015 |
9512568 |
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15370198 |
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14202028 |
Mar 10, 2014 |
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14734609 |
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61784956 |
Mar 14, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 17/40 20130101;
C08F 20/56 20130101; C08F 2810/10 20130101; D21H 21/10 20130101;
C08F 8/12 20130101; D21H 17/455 20130101; D21H 17/45 20130101; C08F
8/48 20130101; D21H 17/375 20130101 |
International
Class: |
D21H 21/10 20060101
D21H021/10; C08F 8/12 20060101 C08F008/12; D21H 17/45 20060101
D21H017/45; D21H 17/37 20060101 D21H017/37; D21H 17/40 20060101
D21H017/40 |
Claims
1. A method for improving retention and drainage in a papermaking
process, comprising: providing a first composition comprising a
water-soluble polymer having hydrolyzable cross-linked monomer
units, the polymer comprising about 1 mol % to about 100 mol %
acrylamide monomers; activating the composition to hydrolyze the
cross-linked monomer units to provide an activated polymer
composition, wherein the activated polymer composition has a
viscosity that is greater than the aqueous composition; and adding
the activated polymer composition to the papermaking process.
2. The method of claim 1, wherein the hydrolyzable cross-linked
monomer units are ionically cross-linked via an ionic interaction
between two monomer units.
3. The method of claim 2, wherein the water-soluble polymer
comprises from about 1 mol % to about 25 mol % ionically
cross-linked monomer units.
4. The method of claim 2, wherein the water-soluble polymer
comprises at least one monomer unit having the following formula
(I): ##STR00016## wherein: R is selected from the group consisting
of --H, C.sub.1-C.sub.24 alkyl, C.sub.2-C.sub.24 alkenyl and
C.sub.2-C.sub.24 alkynyl; each R.sup.a is independently selected
from the group consisting of --H, optionally substituted
C.sub.1-C.sub.50 alkyl, optionally substituted C.sub.2-C.sub.50
alkenyl, optionally substituted C.sub.2-C.sub.50 alkynyl and
optionally substituted aryl; A is selected from the group
consisting of O, S and NR.sup.b; R.sup.b is selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.24 alkyl,
optionally substituted C.sub.2-C.sub.24 alkenyl and optionally
substituted C.sub.2-C.sub.24 alkynyl; B is selected from the group
consisting of optionally substituted C.sub.1-C.sub.24 alkylenyl,
optionally substituted C.sub.2-C.sub.24 alkenylenyl, optionally
substituted C.sub.2-C.sub.24 alkynylenyl and optionally substituted
C.sub.2-C.sub.24 heteroalkylenyl; Z.sup..theta. is an anion; and
each represents a point of attachment to the polymer backbone.
5. The method of claim 4, wherein the monomer unit of formula (I)
is derived from a monomer selected from the group consisting of
N,N-dimethylaminoethyl acrylate methyl chloride quaternary salt,
N,N-dimethylaminoethyl methacrylate methyl chloride quaternary
salt, N,N-dimethylaminopropyl acrylamide methyl chloride quaternary
salt, and N,N-dimethylaminopropyl methacrylamide methyl chloride
quaternary salt.
6. The method of claim 4, wherein the water-soluble polymer further
comprises at least one anionic monomer unit derived from a monomer
selected from the group consisting of an acrylic acid salt, a
methacrylic acid salt, a 2-acrylamido-2-methylpropane sulfonic acid
salt and a styrene sulfonic acid salt.
7. The method of claim 1, wherein the hydrolyzable cross-linked
monomer units are covalently cross-linked.
8. The method of claim 7, wherein the covalently cross-linked
monomer units have the following formula (II): ##STR00017##
wherein: each X is selected from the group consisting of O, S and
NR.sup.b; each R.sup.b is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.24 alkyl,
optionally substituted C.sub.2-C.sub.24 alkenyl and optionally
substituted C.sub.2-C.sub.24 alkynyl; each R is independently
selected from the group consisting of --H, optionally substituted
C.sub.1-C.sub.24 alkyl, optionally substituted C.sub.2-C.sub.24
alkenyl and optionally substituted C.sub.2-C.sub.24 alkynyl; Y is
selected from a group consisting of a bond and a linker comprising
1 to about 1000 member atoms; and each represents a point of
attachment to a first polymer backbone, and each represents a point
of attachment to the first polymer backbone or to a second polymer
backbone.
9. The method of claim 7, wherein the covalently cross-linked
monomer units have the following formula (IIa): ##STR00018##
wherein: each R is independently selected from the group consisting
of --H and --CH.sub.3; Z is selected from the group consisting of a
bond and a C.sub.1-C.sub.12 alkylenyl group; and each represents a
point of attachment to a first polymer backbone, and each
represents a point of attachment to the first polymer backbone or
to a second polymer backbone.
10. The method of claim 7, wherein the covalently cross-linked
monomer units have the following formula (IIb): ##STR00019##
11. The method of claim 7, wherein the water-soluble polymer
comprises about 0.1 ppm to about 20000 ppm covalently cross-linked
monomer units.
12. The method of claim 1, wherein the water-soluble polymer
comprises about 0.1 ppm to about 100 ppm covalently cross-linked
monomer units.
13. The method of claim 1, wherein the aqueous composition
comprises about 100 ppm to about 10000 ppm of the water-soluble
polymer.
14. The method of claim 1, wherein the aqueous composition further
comprises an additional retention aid, a filler, an optical
brightening agent, a dye, a sizing agent, cationic starch, a
fixative, a detackifier, a dispersant, a wet or dry strength
additive, or any combination thereof.
15. The method of claim 1, wherein prior to activation, the first
composition has a viscosity of about 0 cPs to about 100 cPs.
16. The method of claim 1, wherein after activation, the activated
polymer composition has a viscosity of about 1 cPs to about 5000
cPs.
17. The method of claim 1, wherein the activating step comprises
heating the first composition, increasing the ionic strength of the
first composition, or increasing the pH of the first
composition.
18. The method of claim 1, comprising adding the activated polymer
composition to a wet end of a papermaking machine.
19. The method of claim 1, comprising adding the activated polymer
composition to a pulp slurry.
Description
TECHNICAL FIELD
[0001] The present invention relates to methods for increasing
retention and drainage in papermaking processes, using high
molecular-weight, water-soluble polymers. Prior to introduction
into the papermaking process, the polymers are temporarily
cross-linked via hydrolyzable cross-linkers. The cross-linkers can
be hydrolyzed prior to addition to the papermaking process,
providing a more viscous, high molecular weight, water soluble
polymer solution which may act as an effective retention, drainage
and formation (RDF) aid.
BACKGROUND
[0002] In the manufacture of paper, a papermaking furnish is formed
into a paper sheet. The papermaking furnish is an aqueous slurry of
cellulosic fiber having a fiber content of about 4 weight percent
(percent dry weight of solids in the furnish) or less, and
generally around 1.5% or less, and often below 1.0% ahead of the
paper machine, while the finished sheet typically has less than 6
weight percent water. Hence the dewatering and retention aspects of
papermaking are extremely important to the efficiency and cost of
the manufacture.
[0003] Gravity dewatering is a preferred method of drainage because
of its relatively low cost. Other methods can also used for
dewatering, for instance vacuum dewatering, pressing, felt blanket
blotting and pressing, evaporation and the like. In actual practice
a combination of such methods is employed to dewater, or dry, the
sheet to the desired water content. An improvement in the
efficiency of drainage processes may decrease the amount of water
required to be removed by other methods and hence improve the
overall efficiency of dewatering and reduce the cost thereof.
[0004] Another aspect of papermaking that is extremely important to
the efficiency and cost is retention of furnish components on and
within the fiber mat. The papermaking furnish represents a system
containing significant amounts of small particles stabilized by
colloidal forces. The papermaking furnish generally contains, in
addition to cellulosic fibers, particles ranging in size from about
5 to about 1000 nm consisting of, for example, cellulosic fines,
mineral fillers (employed to increase opacity, brightness and other
paper characteristics) and other small particles that generally,
without the inclusion of one or more retention aids, would in
significant portion pass through the spaces (pores) between the mat
formed by the cellulosic fibers on the paper machine.
[0005] Greater retention of fines, fillers, and other components of
the furnish permits, for a given grade of paper, a reduction in the
cellulosic fiber content of such paper. As pulps of lower quality
are employed to reduce papermaking costs, the retention aspect of
papermaking becomes more important because the fines content of
such lower quality pulps is generally greater. Greater retention
also decreases the amount of such substances lost to the whitewater
and hence reduces the amount of material costs, the impact of
increasing levels of such substances with respect to deposition and
contamination, the cost of waste disposal and the adverse
environmental effects therefrom. It is generally desirable to
reduce the amount of material employed in a papermaking process for
a given purpose, without diminishing the result sought. Such add-on
reductions may realize both a material cost savings and handling
and processing benefits.
[0006] Another important characteristic of a given papermaking
process is the formation of the paper sheet produced. Formation may
be determined by the variance in light transmission within a paper
sheet, and a high variance is indicative of poor formation. As
retention increases to a high level, for instance a retention level
of 80 or 90%, the formation parameter generally declines.
[0007] Various chemical additives have been utilized in an attempt
to increase the rate at which water drains from the formed sheet,
and to increase the amount of fines and filler retained on the
sheet. For example, high molecular weight polymers can act as
flocculants, forming large flocs which deposit on the sheet. They
may also aid in the dewatering of the sheet. In conventional
programs, the high molecular weight component is added after a high
shear point in the stock flow system leading up to the headbox of
the paper machine. This is optimal as flocs are formed primarily by
a bridging mechanism and their breakdown is a largely irreversible
process. For this reason, most of the retention and drainage
performance of a flocculant is lost by feeding it before a high
shear point. However, feeding high molecular weight polymers after
the high shear point often leads to formation problems. The feed
requirements of the high molecular weight polymers and copolymers
which provide improved retention often lead to a compromise between
retention and formation.
[0008] There is therefore continuing need to develop new retention
aids to increase the efficiency of pulp or paper manufacture.
SUMMARY
[0009] The present invention is generally directed to methods of
using water-soluble, high molecular weight polymers for increasing
retention and drainage in a papermaking furnish.
[0010] In one aspect, the present invention is directed to a method
for improving retention and drainage in a papermaking process,
comprising:
[0011] providing a first composition comprising a water-soluble
polymer having hydrolyzable cross-linked monomer units, the polymer
comprising about 1 mol % to about 100 mol % acrylamide
monomers;
[0012] activating the composition to hydrolyze the cross-linked
monomer units to provide an activated polymer composition, wherein
the activated polymer composition has a viscosity that is greater
than the aqueous composition; and
[0013] adding the activated polymer composition to the papermaking
process.
[0014] In some embodiments, the hydrolyzable cross-linked monomer
units are ionically cross-linked via an ionic interaction between
two monomer units. In some embodiments, the water-soluble polymer
comprises from about 1 mol % to about 25 mol % ionically
cross-linked monomer units.
[0015] In some embodiments, the water-soluble polymer comprises at
least one monomer unit having the following formula (I):
##STR00001##
wherein:
[0016] R is selected from the group consisting of --H,
C.sub.1-C.sub.24 alkyl, C.sub.2-C.sub.24 alkenyl and
C.sub.2-C.sub.24 alkynyl;
[0017] each R.sup.a is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.50 alkyl,
optionally substituted C.sub.2-C.sub.50 alkenyl, optionally
substituted C.sub.2-C.sub.50 alkynyl and optionally substituted
aryl;
[0018] A is selected from the group consisting of O, S and
NR.sup.b;
[0019] R.sup.b is selected from the group consisting of --H,
optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0020] B is selected from the group consisting of optionally
substituted C.sub.1-C.sub.24 alkylenyl, optionally substituted
C.sub.2-C.sub.24 alkenylenyl, optionally substituted
C.sub.2-C.sub.24 alkynylenyl and optionally substituted
C.sub.2-C.sub.24 heteroalkylenyl;
[0021] Z.sup..theta. is an anion; and
[0022] each represents a point of attachment to the polymer
backbone.
[0023] In some embodiments, the monomer unit of formula (I) is
derived from a monomer selected from the group consisting of
N,N-dimethylaminoethyl acrylate methyl chloride quaternary salt,
N,N-dimethylaminoethyl methacrylate methyl chloride quaternary
salt, N,N-dimethylaminopropyl acrylamide methyl chloride quaternary
salt, and N,N-dimethylaminopropyl methacrylamide methyl chloride
quaternary salt. In some embodiments, the water-soluble polymer
further comprises at least one anionic monomer unit derived from a
monomer selected from the group consisting of an acrylic acid salt,
a methacrylic acid salt, a 2-acrylamido-2-methylpropane sulfonic
acid salt and a styrene sulfonic acid salt. In some embodiments,
the hydrolyzable cross-linked monomer units are covalently
cross-linked.
[0024] In some embodiments, the covalently cross-linked monomer
units have the following formula (II):
##STR00002##
wherein:
[0025] each X is selected from the group consisting of O, S and
NR.sup.b;
[0026] each R.sup.b is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.24 alkyl,
optionally substituted C.sub.2-C.sub.24 alkenyl and optionally
substituted C.sub.2-C.sub.24 alkynyl;
[0027] each R is independently selected from the group consisting
of --H, optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0028] Y is selected from a group consisting of a bond and a linker
comprising 1 to about 1000 member atoms; and
[0029] each represents a point of attachment to a first polymer
backbone, and each represents a point of attachment to the first
polymer backbone or to a second polymer backbone.
[0030] In some embodiments, the covalently cross-linked monomer
units have the following formula (IIa):
##STR00003##
wherein:
[0031] each R is independently selected from the group consisting
of --H and --CH.sub.3;
[0032] Z is selected from the group consisting of a bond and a
C.sub.1-C.sub.12 alkylenyl group; and
[0033] each represents a point of attachment to a first polymer
backbone, and each represents a point of attachment to the first
polymer backbone or to a second polymer backbone.
[0034] In some embodiments, the covalently cross-linked monomer
units have the following formula (IIb):
##STR00004##
[0035] In some embodiments, the water-soluble polymer comprises
about 0.1 ppm to about 20000 ppm covalently cross-linked monomer
units. In some embodiments, the water-soluble polymer comprises
about 0.1 ppm to about 100 ppm covalently cross-linked monomer
units. In some embodiments, the aqueous composition comprises about
100 ppm to about 10000 ppm of the water-soluble polymer. In some
embodiments, the aqueous composition further comprises an
additional retention aid, a filler, an optical brightening agent, a
dye, a sizing agent, cationic starch, a fixative, a detackifier, a
dispersant, a wet or dry strength additive, or any combination
thereof.
[0036] In some embodiments, prior to activation, the first
composition has a viscosity of about 0 cPs to about 100 cPs. In
some embodiments, after activation, the activated polymer
composition has a viscosity of about 1 cPs to about 5000 cPs. In
some embodiments, the activating step comprises heating the first
composition, increasing the ionic strength of the first
composition, or increasing the pH of the first composition. In some
embodiments, the method comprises adding the activated polymer
composition to a wet end of a papermaking machine. In some
embodiments, the method comprises adding the activated polymer
composition to a pulp slurry.
[0037] Other aspects and embodiments of the invention will become
apparent in light of the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a graph of the results of a first pass retention
test for various dosages of water-soluble polymers. Error bars
represent the 90% confidence intervals.
[0039] FIG. 2 is a graph of the results of a first pass retention
test for various dosages of water-soluble polymers. Error bars
represent the 90% confidence intervals.
[0040] FIG. 3 is a graph of the results of a first pass retention
test for various dosages of water-soluble polymers. Error bars
represent the 90% confidence intervals.
[0041] FIG. 4 is a graphical representation of the first pass
retention % versus the polymer dosage.
DETAILED DESCRIPTION
[0042] The present invention is directed to methods of using
water-soluble, high molecular weight polymers in papermaking
processes, specifically as retention, drainage and/or formation
(RDF) aids. The polymers comprise hydrolyzable cross-linked
monomers, which can be activated to facilitate hydrolysis of the
cross-linkers. The hydrolysis leads to an increase in viscosity of
the composition, due to the increase in the hydrodynamic volume of
the high molecular weight polymers that are uncrosslinked. The
viscosity of the resulting composition is higher than that of a
composition comprising a near-identical polymer that lacks the
hydrolyzable cross-links. The high molecular weight and the
significant hydrodynamic volume of the polymers in the activated
polymer composition leads to their effective use as flocculants in
papermaking processes.
[0043] The high molecular weights achievable with the water-soluble
polymers described herein allows for their very effective use in
RDF applications. Furthermore, the ability to regulate the
viscosity of the compositions allows for the introduction and
delivery systems to be used that would not be possible with current
polymers used in these applications, without reduced
performance.
1. DEFINITIONS
[0044] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art. In case of conflict, the present
document, including definitions, will control. Preferred methods
and materials are described below, although methods and materials
similar or equivalent to those described herein can be used in
practice or testing of the present invention. All publications,
patent applications, patents and other references mentioned herein
are incorporated by reference in their entirety. The materials,
methods, and examples disclosed herein are illustrative only and
not intended to be limiting.
[0045] The terms "comprise(s)," "include(s)," "having," "has,"
"can," "contain(s)," and variants thereof, as used herein, are
intended to be open-ended transitional phrases, terms, or words
that do not preclude the possibility of additional acts or
structures. The singular forms "a," "and" and "the" include plural
references unless the context clearly dictates otherwise.
[0046] The present disclosure also contemplates other embodiments
"comprising," "consisting of" and "consisting essentially of," the
embodiments or elements presented herein, whether explicitly set
forth or not.
[0047] The term "alkyl," as used herein, refers to a linear or
branched hydrocarbon radical, preferably having 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons. Alkyl groups
include, but are not limited to, methyl, ethyl, n-propyl,
isopropyl, n-butyl, iso-butyl, secondary-butyl, and tertiary-butyl.
Alkyl groups may be unsubstituted or substituted by one or more
suitable substituents, as defined below.
[0048] The term "alkylenyl" or "alkylene," as used herein, refers
to a divalent group derived from a saturated, straight or branched
hydrocarbon chain of from 1 to 50 carbon atoms. The term
"C.sub.1-C.sub.6 alkylene" means those alkylene or alkylenyl groups
having from 1 to 6 carbon atoms. Representative examples of
alkylenyl groups include, but are not limited to, --CH.sub.2--,
--CH(CH.sub.3)--, --CH(C.sub.2H.sub.5)--,
--CH(CH(CH.sub.3)(C.sub.2H.sub.5))--,
--C(H)(CH.sub.3)CH.sub.2CH.sub.2--, --C(CH.sub.3).sub.2--,
--CH.sub.2CH.sub.2--, --CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2--, and
--CH.sub.2CH(CH.sub.3)CH.sub.2--. Alkylenyl groups may be
unsubstituted or substituted by one or more suitable substituents,
as defined below.
[0049] The term "alkenyl," as used herein, refers to a straight or
branched hydrocarbon radical, preferably having 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons, and having one or
more carbon-carbon double bonds. Alkenyl groups include, but are
not limited to, ethenyl, 1-propenyl, 2-propenyl (allyl),
iso-propenyl, 2-methyl-1-propenyl, 1-butenyl, and 2-butenyl.
Alkenyl groups may be unsubstituted or substituted by one or more
suitable substituents, as defined below.
[0050] The term "alkenylenyl" or "alkenylene," as used herein,
refers to a divalent group derived from a straight or branched
chain hydrocarbon of 2 to 50 carbon atoms, which contains at least
one carbon-carbon double bond. Representative examples of
alkenylenyl groups include, but are not limited to,
--C(H).dbd.C(H)--, --C(H).dbd.C(H)--CH.sub.2--,
--C(H).dbd.C(H)--CH.sub.2--CH.sub.2--,
--CH.sub.2--C(H).dbd.C(H)--CH.sub.2--,
--C(H).dbd.C(H)--CH(CH.sub.3)--, and
--CH.sub.2--C(H).dbd.C(H)--CH(CH.sub.2CH.sub.3)--. Alkenylenyl
groups may be unsubstituted or substituted by one or more suitable
substituents, as defined below.
[0051] The term "alkynyl," as used herein, refers to a straight or
branched hydrocarbon radical, preferably having 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons, and having one or
more carbon-carbon triple bonds. Alkynyl groups include, but are
not limited to, ethynyl, propynyl, and butynyl. Alkynyl groups may
be unsubstituted or substituted by one or more suitable
substituents, as defined below.
[0052] The term "alkynylenyl" or "alkynylene," as used herein,
refers to a divalent unsaturated hydrocarbon group derived from a
straight or branched chain hydrocarbon of 2 to 50 carbon atoms, and
which has at least one carbon-carbon triple bond. Representative
examples of alkynylenyl groups include, but are not limited to,
--C.ident.C--, --C.ident.C--CH.sub.2--,
--C.ident.C--CH.sub.2--CH.sub.2--,
--CH.sub.2--C.ident.C--CH.sub.2--, --C.ident.C--CH(CH.sub.3)--, and
--CH.sub.2--C.ident.C--CH(CH.sub.2CH.sub.3)--. Alkynylenyl groups
may be unsubstituted or substituted by one or more suitable
substituents, as defined below.
[0053] The term "alkoxy," as used herein, refers to an alkyl group,
as defined herein, appended to the parent molecular moiety through
an oxygen atom.
[0054] The term "aryl," as used herein, means monocyclic, bicyclic,
or tricyclic aromatic radicals such as phenyl, naphthyl,
tetrahydronaphthyl, indanyl and the like; optionally substituted by
one or more suitable substituents, preferably 1 to 5 suitable
substituents, as defined below.
[0055] The term "carbonyl," "(C.dbd.O)," or "--C(O)--" (as used in
phrases such as alkylcarbonyl, alkyl --(C.dbd.O)-- or
alkoxycarbonyl) refers to the joinder of the >C.dbd.O moiety to
a second moiety such as an alkyl or amino group (i.e. an amido
group). Alkoxycarbonylamino (i.e. alkoxy(C.dbd.O)--NH--) refers to
an alkyl carbamate group. The carbonyl group is also equivalently
defined herein as (C.dbd.O). Alkylcarbonylamino refers to groups
such as acetamide.
[0056] The term "cross-link," as used herein, refers to a bond that
links one monomer unit of a polymer chain to another monomer unit
of a polymer chain. The bond can be a covalent bond or an ionic
bond.
[0057] The term "cycloalkyl," as used herein, refers to a mono,
bicyclic or tricyclic carbocyclic radical (e.g., cyclopropyl,
cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl,
cyclononyl, cyclopentenyl, cyclohexenyl, bicyclo[2.2.1]heptanyl,
bicyclo[3.2.1]octanyl and bicyclo[5.2.0]nonanyl, etc.); optionally
containing 1 or 2 double bonds. Cycloalkyl groups may be
unsubstituted or substituted by one or more suitable substituents,
preferably 1 to 5 suitable substituents, as defined above.
[0058] The term "halo" or "halogen," as used herein, refers to a
fluoro, chloro, bromo or iodo radical.
[0059] The term "heteroalkylenyl" or "heteroalkylene," as used
herein, refers to a divalent group derived from a saturated,
straight or branched hydrocarbon chain, in which at least one atom
is a heteroatom such as O, S, N, Si or P. The terms
"C.sub.1-C.sub.24 heteroalkylenyl," "C.sub.1-C.sub.12
heteroalkylenyl" and "C.sub.1-C.sub.6 heteroalkylene" refer to
those heteroalkylene or heteroalkylenyl groups having from 1 to 24
atoms, 1 to 12 atoms or 1 to 6 member atoms, respectively, wherein
the atoms are either carbon or a heteroatom. Representative
examples of heteroalkylenyl groups include, but are not limited to,
--O(CH.sub.2CH.sub.2O).sub.n-- and
--O(CH.sub.2CH.sub.2CH.sub.2O).sub.n--, wherein each n is
independently 1 to 12. Heteroalkylenyl groups may be unsubstituted
or substituted by one or more suitable substituents, as defined
below.
[0060] The term "heteroaryl," as used herein, refers to a
monocyclic, bicyclic, or tricyclic aromatic heterocyclic group
containing one or more heteroatoms selected from O, S and N in the
ring(s). Heteroaryl groups include, but are not limited to,
pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, thienyl, furyl,
imidazolyl, pyrrolyl, oxazolyl (e.g., 1,3-oxazolyl, 1,2-oxazolyl),
thiazolyl (e.g., 1,2-thiazolyl, 1,3-thiazolyl), pyrazolyl,
tetrazolyl, triazolyl (e.g., 1,2,3-triazolyl, 1,2,4-triazolyl),
oxadiazolyl (e.g., 1,2,3-oxadiazolyl), thiadiazolyl (e.g.,
1,3,4-thiadiazolyl), quinolyl, isoquinolyl, benzothienyl,
benzofuryl, and indolyl. Heteroaryl groups may be unsubstituted or
substituted by one or more suitable substituents, preferably 1 to 5
suitable substituents, as defined below.
[0061] The term "heterocycle," as used herein, refers to a
monocyclic, bicyclic, or tricyclic group containing 1 to 4
heteroatoms selected from N, O, S(O).sub.n, NH or NR.sup.x, wherein
R.sup.x is a suitable substituent. Heterocyclic groups optionally
contain 1 or 2 double bonds. Heterocyclic groups include, but are
not limited to, azetidinyl, tetrahydrofuranyl, imidazolidinyl,
pyrrolidinyl, piperidinyl, piperazinyl, oxazolidinyl,
thiazolidinyl, pyrazolidinyl, thiomorpholinyl, tetrahydrothiazinyl,
tetrahydro-thiadiazinyl, morpholinyl, oxetanyl, tetrahydrodiazinyl,
oxazinyl, oxathiazinyl, indolinyl, isoindolinyl, quinuclidinyl,
chromanyl, isochromanyl, and benzoxazinyl. Examples of monocyclic
saturated or partially saturated ring systems are
tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, imidazolidin-1-yl,
imidazolidin-2-yl, imidazolidin-4-yl, pyrrolidin-1-yl,
pyrrolidin-2-yl, pyrrolidin-3-yl, piperidin-1-yl, piperidin-2-yl,
piperidin-3-yl, piperazin-1-yl, piperazin-2-yl, piperazin-3-yl,
1,3-oxazolidin-3-yl, isothiazolidinyl, 1,3-thiazolidin-3-yl,
1,2-pyrazolidin-2-yl, 1,3-pyrazolidin-1-yl, thiomorpholin-yl,
1,2-tetrahydrothiazin-2-yl, 1,3-tetrahydrothiazin-3-yl,
tetrahydrothiadiazin-yl, morpholin-yl, 1,2-tetrahydrodiazin-2-yl,
1,3-tetrahydrodiazin-1-yl, 1,4-oxazin-2-yl, and
1,2,5-oxathiazin-4-yl. Heterocyclic groups may be unsubstituted or
substituted by one or more suitable substituents, preferably 1 to 3
suitable substituents, as defined below.
[0062] The term "high molecular weight," as used herein in
connection with a water-soluble polymer, refers to a polymer that
has a molecular weight of at least about 500 kDa. In some
embodiments, the term "high molecular weight" refers to a polymer
that has a molecular weight of at least about 5000 kDa.
[0063] The term "hydrodynamic volume," as used herein, refers to a
measure of the size of the polymer in a composition, whereby the
volume exerts a primary influence on the bulk viscosity of the
composition of the polymer. Hydrodynamic volume may further refer
to the volume of a polymer chain when it is in a composition. This
may vary for a polymer depending on how well it interacts with the
solvent, and the polymer's molecular weight. The solvent properties
can be influenced by the concentration and type of ionic species
dissolved within the solvent.
[0064] The term "hydrolyzable," as used herein, refers to a bond or
a moiety that can be cleaved by the addition of water.
[0065] The term "hydrolyzable cross-link," as used herein, refers
to a cross-link as defined above that may be cleaved by hydrolysis
(addition of water).
[0066] The term "hydroxy," as used herein, refers to an --OH
group.
[0067] "Member atom" as used herein refers to a polyvalent atom
(e.g., a C, O, N, S or P atom) in a chain or ring system that
constitutes a part of the chain or ring. For example, in pyridine,
five carbon atoms and one nitrogen atom are member atoms of the
ring. In diethyl ether, four carbon atoms and one oxygen atom are
member atoms of the chain. Member atoms will be substituted up to
their normal valence. For example, in an alkylenyl chain, each
carbon atom will be substituted with two hydrogen atoms, or one
hydrogen atom and one other substituent (e.g., an alkyl group or a
hydroxyl group), or two substituents (e.g., two alkyl groups).
Alternatively, a carbon atom can be substituted with an oxo group
to form a --C(O)-- group.
[0068] The term "oxo," as used herein, refers to a double bonded
oxygen (.dbd.O) radical wherein the bond partner is a carbon atom.
Such a radical can also be thought as a carbonyl group.
[0069] "Papermaking process" means a method of making paper and
paperboard products from pulp comprising forming an aqueous
cellulosic papermaking furnish (optionally, with mineral fillers,
such as calcium carbonates, clays, etc.), draining the furnish to
form a sheet, and drying the sheet. It should be appreciated that
any suitable furnish may be used. Representative furnishes include,
for example, virgin pulp, recycled pulp, kraft pulp (bleached and
unbleached), sulfite pulp, mechanical pulp, polymeric plastic
fibers, the like, any combination of the foregoing pulps. The steps
of forming the papermaking furnish, draining and drying may be
carried out in any manner generally known to those skilled in the
art.
[0070] The term "substituent," as used herein, is intended to mean
a chemically acceptable functional group that is "substituted" at
any suitable atom of that group. Suitable substituents include, but
are not limited to halo groups, perfluoroalkyl groups,
perfluoroalkoxy groups, alkyl groups, alkenyl groups, alkynyl
groups, hydroxy groups, oxo groups, mercapto groups, alkylthio
groups, alkoxy groups, aryl or heteroaryl groups, aryloxy or
heteroaryloxy groups, aralkyl or heteroaralkyl groups,
HO--(C.dbd.O)-- groups, heterocylic groups, cycloalkyl groups,
amino groups, alkyl--and dialkylamino groups, carbamoyl groups,
alkylcarbonyl groups, alkoxycarbonyl groups, alkylaminocarbonyl
groups, dialkylamino carbonyl groups, arylcarbonyl groups,
aryloxycarbonyl groups, alkylsulfonyl groups, arylsulfonyl groups,
groups of formula --(OCH.sub.2).sub.tOH wherein t is 1 to 25, and
groups of formula -alkylenyl-(OCH.sub.2).sub.tOH wherein t is 1 to
25. Those skilled in the art will appreciate that many substituents
can be substituted with additional substituents.
[0071] The term "viscosity," as used herein, expressed as the ratio
of shear stress (force per unit area) to the shear rate (rate
change of shear strain), refers to a fluid's resistance to flow.
Viscosity may further be described as the internal friction of a
moving fluid. A fluid with a high viscosity may resist motion
because its molecular makeup provides significant internal
friction. A fluid with low viscosity may flow easily because its
molecular makeup results in very little friction when it is in
motion.
"Wet end" may refer to that portion of a papermaking process
involving an approach system, a sheet forming section and/or a
pressing section.
[0072] For the recitation of numeric ranges herein, each
intervening number there between with the same degree of precision
is explicitly contemplated. For example, for the range of 6-9, the
numbers 7 and 8 are contemplated in addition to 6 and 9, and for
the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6,
6.7, 6.8, 6.9, and 7.0 are explicitly contemplated.
2. METHODS OF IMPROVING RETENTION AND DRAINAGE IN A PAPERMAKING
PROCESS
[0073] Disclosed herein are methods of improving retention and
drainage in papermaking processes. The methods comprise the steps
of: providing a first composition comprising a water-soluble
polymer having hydrolyzable cross-linked monomer units, the polymer
comprising about 1 mol % to about 100 mol % acrylamide monomers;
activating the first composition to hydrolyze the cross-linked
monomer units to provide an activated polymer composition, wherein
the activated polymer composition has a viscosity that is greater
than the viscosity of the first composition; and adding the
activated polymer composition to the papermaking process. The first
composition can be in the form of a solution or an emulsion, and
the activated polymer composition can be in the form of a solution
or an emulsion.
[0074] The first composition comprising the water-soluble polymer
can be activated to hydrolyze the cross-linked monomer units using
a number of methods. In some embodiments, the first composition can
be heated to activate hydrolysis of the cross-linked monomer units.
For example, the first composition can be heated to a temperature
of about 30.degree. C. to about 100.degree. C., e.g., about
30.degree. C., 35.degree. C., 40.degree. C., 45.degree. C.,
50.degree. C., 55.degree. C., 60.degree. C., 65.degree. C.,
70.degree. C., 75.degree. C., 80.degree. C., 85.degree. C.,
90.degree. C., 95.degree. C. or 100.degree. C. The first
composition can be heated for about 30 minutes to about 24 hours,
e.g., for about 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5
hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12
hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours,
19 hours, 20 hours, 21 hours, 22 hours, 23 hours, or 24 hours.
[0075] In some embodiments, the first composition can be subjected
to a change in ionic strength. This can be effected, for example,
by adding a salt or a solution thereof to the first composition.
The salt may be, for example, sodium chloride or the like.
In some embodiments, the first composition can be subjected to a
change in pH. This can be effected, for example, by adding a base
or a solution thereof to the first composition. The salt may be,
for example, sodium hydroxide, potassium hydroxide, sodium
bicarbonate, potassium bicarbonate, sodium carbonate, potassium
carbonate, triethylamine or the like. The base may be added in an
amount sufficient to increase the pH of the composition to about
7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4,
8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8,
9.9 or 10.
[0076] The activated polymer composition may be added to a
papermaking process involving virgin pulp, recycled pulp or
combination thereof at any one or more of various locations during
the papermaking process. Suitable locations may include a pulper,
latency chest, reject refiner chest, disk filter or Decker feed or
accept, whitewater system, pulp stock storage chest (either low
density ("LD"), medium consistency (MC), or high consistency (HC)),
blend chest, machine chest, headbox, saveall chest, paper machine
whitewater system, and combinations thereof. The activated polymer
composition may also be added to a pulp slurry in the papermaking
process.
[0077] The activated polymer composition may be added in an amount
effective to improve retention and drainage in a papermaking
process. For example, the activated polymer composition may be
added in an about of about 0.01 to about 2.0 lb per ton of
papermaking furnish, or about 0.10 to about 1.0 lb per ton of
papermaking furnish, e.g., 0.10, 0.125, 0.15, 0.175, 0.20, 0.225,
0.25, 0.275, 0.30, 0.325, 0.35, 0.375, 0.40, 0.425, 0.45, 0.475,
0.50, 0.525, 0.55, 0.575, 0.60, 0.625, 0.65, 0.675, 0.70, 0.725,
0.75, 0.775, 0.80, 0.825, 0.85, 0.875, 0.90, 0.925, 0.95, 0.975, or
1.00 lb per ton of papermaking furnish.
[0078] In some embodiments, the activated water-soluble polymers
described herein may be effective as RDF aids in papermaking
processes at lower doses than are required for conventional RDF
aids. For example, the methods described herein may require a dose
of the activated water-soluble polymer that is about 1%, 2%, 3%,
4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%,
18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%,
31%, 32%, 33%, 34%, 35% less than a dose of a conventional
water-soluble polymer, such as those used commercially as RDF aids
in current papermaking processes. In embodiments, the methods may
require a dose of the water-soluble polymer that is about 1%, 2%,
3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%,
18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%,
31%, 32%, 33%, 34%, 35% less than a corresponding water-soluble
polymer that lacks the hydrolyzable cross-linked monomers.
[0079] The performance of polymers as RDF aids can be evaluated
using a method known as the first pass retention test, which uses a
Britt CF Dynamic Drainage Jar developed by K. W. Britt of New York
State University. The Britt Jar generally includes an upper chamber
of about 1 liter capacity and a bottom drainage chamber, the
chamber being separated by a support screen and a drainage screen.
Below the drainage chamber is a downward extending flexible tube
equipped with a clamp for closure. The upper chamber is provided
with a variable speed, high torque motor equipped with a 2-inch
3-bladed propeller to create controlled shear conditions in the
upper chamber. The test is conducted by placing a cellulosic slurry
in the upper chamber and then subjecting the slurry to sequences
involving commencing of shear stirring, adding of a starch and
coagulant (if necessary), adding a test polymer, starting draining,
and stopping draining and analyzing the filtrate. The entire
sequence can take place over a time period of about one minute or a
similar time frame. The material drained from the Britt jar (the
"filtrate") is collected and filtered, and then the filter pad and
filtrate are then dried and the dry mass of the filtrate is
determined. The first pass retention value is calculated using the
following formula:
First Pass Retention ( % ) = ( Cellulosic slurry consistency -
Filtrate consistency Cellulosic slurry consistency ) .times. 100
##EQU00001##
[0080] a. Water-Soluble Polymers
[0081] The methods involve adding to the papermaking process an
activated polymer composition, which is prepared from a first
composition comprising water-soluble polymers having hydrolyzable
cross-linked monomer units. The hydrolyzable cross-linked monomer
units are hydrolyzed upon activation by exposure to a stimulus,
such as a change in temperature or chemical environment (e.g., pH,
concentration or ionic strength). For example, the water-soluble
polymers may be incorporated into a first composition, which may be
subjected to a stimulus to activate hydrolysis of the hydrolyzable
cross-links, thereby forming the activated polymer composition.
[0082] The hydrolyzable cross-linked monomer units may be
cross-linked via a covalent hydrolyzable cross-linker, or via ionic
interactions between a monomer unit bearing a charged hydrolyzable
moiety and a monomer unit bearing an opposite charge.
[0083] When the polymers are dissolved in an aqueous solution, they
provide the aqueous polymer solution with a relatively low
viscosity. If the aqueous solution is subjected to altered
conditions, such as an increase in temperature, a change in ionic
strength, or a change in pH, the viscosity may increase to an
amount greater than the starting solution viscosity, and/or an
amount greater than the viscosity of an aqueous solution comprising
the same polymer lacking the hydrolyzable cross-links.
[0084] The water-soluble polymers that may be used in the methods
of the present invention comprise about 1 mol % to about 99 mol %
acrylamide monomer units. For example, the polymer may comprise
about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68,
69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85,
86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99 mol %
acrylamide monomers. In some embodiments, the water-soluble
polymers comprise about 20 mol % to about 80 mol % acrylamide
monomers. In some embodiments, the water-soluble polymers comprise
about 60 mol % to about 80 mol % acrylamide monomers.
[0085] The water-soluble polymer may comprise additional monomer
units, which may be selected from the group consisting of: acrylic
acid or a salt thereof, methacrylic acid or a salt thereof,
2-acrylamido-2-methylpropane sulfonic acid or a salt thereof,
acrolein, styrene sulfonic acid or a salt thereof, N-vinyl
formamide, N-vinyl pyrrolidone, N,N-dimethylaminoethyl acrylate or
a quaternized salt thereof, N,N-dimethylaminoethyl methacrylate or
a quaternized salt thereof, N,N-dimethylaminopropyl acrylamide or a
quaternized salt thereof, N,N-dimethylaminopropyl methacrylamide or
a quaternized salt thereof, N,N-dimethyldiallylammonium chloride,
N,N-diallylamine, and a hydrophobic monomer such as lauryl
methacrylate. For example, the water-soluble copolymer may further
comprise monomer units selected from the group consisting of
acrylic acid or a salt thereof, 2-acrylamido-2-methylpropane
sulfonic acid or a salt thereof, acrolein,
dimethylaminoethylacrylate methyl chloride quaternary salt
(DMAEA.MCQ), and dimethylaminoethylmethacrylate methyl chloride
quaternary salt (DMAEM.MCQ). If present, each of the above monomer
units may be included in a polymer in an amount of about 1 mol % to
about 99 mol %. For example, the polymer may comprise about 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,
55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
89, 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99 mol % of the above
monomer units. In some embodiments, the water-soluble polymers
comprise about 10 mol % to about 60 mol % of the above monomer
units. In some embodiments, the water-soluble polymers comprise
about 20 mol % to about 40 mol % of the above monomer units.
[0086] The water-soluble polymer may be a homopolymer (e.g., a
homopolymer of acrylamide), or a copolymer or a terpolymer. In the
case of copolymers and terpolymers, the polymer may be any form of
copolymer or terpolymer, such as an alternating copolymer, a
periodic copolymer, a random copolymer, or a block copolymer (e.g.,
a diblock copolymer or a triblock copolymer). The polymer may be a
linear polymer or a branched polymer (e.g., a hyperbranched polymer
or a dendritic polymer).
[0087] Following exposure of a composition comprising the
water-soluble polymer to an external stimulus such as an increase
in temperature or a change in chemical environment such as pH,
concentration or ionic strength, and hydrolysis of any cross-linked
monomer units, the water-soluble polymer may have a molecular
weight of greater than about 500 kDa, or from about 500 kDa to
about 50000 kDa, or from about 1000 kDa to about 25000 kDa. For
example, a water-soluble polymer may have a molecular weight of
about 500 kDa, 600 kDa, 700 kDa, 800 kDa, 900 kDa, 1000 kDa, 1100
kDa, 1200 kDa, 1300 kDa, 1400 kDa, 1500 kDa, 1600 kDa, 1700 kDa,
1800 kDa, 1900 kDa, 2000 kDa, 2100 kDa, 2200 kDa, 2300 kDa, 2400
kDa, 2500 kDa, 2600 kDa, 2700 kDa, 2800 kDa, 2900 kDa, 3000 kDa,
3100 kDa, 3200 kDa, 3300 kDa, 3400 kDa, 3500 kDa, 3600 kDa, 3700
kDa, 3800 kDa, 3900 kDa, 4000 kDa, 4100 kDa, 4200 kDa, 4300 kDa,
4400 kDa, 4500 kDa, 4600 kDa, 4700 kDa, 4800 kDa, 4900 kDa, 5000
kDa, 5100 kDa, 5200 kDa, 5300 kDa, 5400 kDa, 5500 kDa, 5600 kDa,
5700 kDa, 5800 kDa, 5900 kDa, 6000 kDa, 6100 kDa, 6200 kDa, 6300
kDa, 6400 kDa, 6500 kDa, 6600 kDa, 6700 kDa, 6800 kDa, 6900 kDa,
7000 kDa, 7100 kDa, 7200 kDa, 7300 kDa, 7400 kDa, 7500 kDa, 7600
kDa, 7700 kDa, 7800 kDa, 7900 kDa, 8000 kDa, 8100 kDa, 8200 kDa,
8300 kDa, 8400 kDa, 8500 kDa, 8600 kDa, 8700 kDa, 8800 kDa, 8900
kDa, 9000 kDa, 9100 kDa, 9200 kDa, 9300 kDa, 9400 kDa, 9500 kDa,
9600 kDa, 9700 kDa, 9800 kDa, 9900 kDa, 10000 kDa, 11000 kDa, 12000
kDa, 13000 kDa, 14000 kDa, 15000 kDa, 16000 kDa, 17000 kDa, 18000
kDa, 19000 kDa, 20000 kDa, 21000 kDa, 22000 kDa, 23000 kDa, 24000
kDa, 25000 kDa, 26000 kDa, 27000 kDa, 28000 kDa, 29000 kDa, 30000
kDa, 31000 kDa, 32000 kDa, 33000 kDa, 34000 kDa, 35000 kDa, 36000
kDa, 37000 kDa, 38000 kDa, 39000 kDa, 40000 kDa, 41000 kDa, 42000
kDa, 43000 kDa, 44000 kDa, 45000 kDa, 46000 kDa, 47000 kDa, 48000
kDa, 49000 kDa or 50000 kDa. Molecular weights may be higher than
50000 kDa in the event of that some of the cross-links remain
unhydrolyzed.
[0088] Following activation of the polymer and hydrolysis of any
cross-linked monomer units, the water-soluble polymer may have a
charge level (e.g., an anionic charge level) of about 10 to about
75 mol %. For example, a water-soluble polymer may have a charge
level of about 10 mol %, 11 mol %, 12 mol %, 13 mol %, 14 mol %, 15
mol %, 16 mol %, 17 mol %, 18 mol %, 19 mol %, 20 mol %, 21 mol %,
22 mol %, 23 mol %, 24 mol %, 25 mol %, 26 mol %, 27 mol %, 28 mol
%, 29 mol %, 30 mol %, 31 mol %, 32 mol %, 33 mol %, 34 mol %, 35
mol %, 36 mol %, 37 mol %, 38 mol %, 39 mol %, 40 mol %, 41 mol %,
42 mol %, 43 mol %, 44 mol %, 45 mol %, 46 mol %, 47 mol %, 48 mol
%, 49 mol %, 50 mol %, 51 mol %, 52 mol %, 53 mol %, 54 mol %, 55
mol %, 56 mol %, 57 mol %, 58 mol %, 59 mol %, 60 mol %, 61 mol %,
62 mol %, 63 mol %, 64 mol %, 65 mol %, 66 mol %, 67 mol %, 68 mol
%, 69 mol %, 70 mol %, 71 mol %, 72 mol %, 73 mol %, 74 mol %, or
75 mol %. In some embodiments, the water-soluble polymers have a
charge level of about 10 mol % to about 60 mol %. In some
embodiments, the water-soluble polymers have a charge level of
about 10 mol % to about 40 mol %.
[0089] (1) Hydrolyzable Ionic Cross-Links
[0090] The water-soluble polymers may include monomer units that
are cross-linked via an ionic interaction, between a monomer unit
bearing a charged hydrolyzable moiety, and a monomer unit bearing
an opposite charge. For example, ionically cross-linked monomer
units may include a monomer unit bearing a hydrolyzable positively
charged moiety, such as a quaternary amine, which interacts with a
negatively charged moiety on the polymer. In another example,
ionically cross-linked monomer units may include a monomer unit
bearing a hydrolyzable negatively charged moiety, such as a
carboxylic acid, which interacts with a positively charged moiety
on the polymer such as a quaternary amine.
[0091] For example, the water-soluble polymer may include at least
one monomer-derived mer unit having the following formula (I):
##STR00005##
wherein:
[0092] R is selected from the group consisting of --H,
C.sub.1-C.sub.24 alkyl, C.sub.2-C.sub.24 alkenyl and
C.sub.2-C.sub.24 alkynyl;
[0093] each R.sup.a is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.50 alkyl,
optionally substituted C.sub.2-C.sub.50 alkenyl, optionally
substituted C.sub.2-C.sub.50 alkynyl and optionally substituted
aryl;
[0094] A is selected from the group consisting of O, S and
NR.sup.b;
[0095] R.sup.b is selected from the group consisting of --H,
optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0096] B is selected from the group consisting of optionally
substituted C.sub.1-C.sub.24 alkylenyl, optionally substituted
C.sub.2-C.sub.24 alkenylenyl, optionally substituted
C.sub.2-C.sub.24 alkynylenyl and optionally substituted
C.sub.2-C.sub.24 heteroalkylenyl;
[0097] Z.sup..theta. is an anion; and
[0098] each represents a point of attachment to the polymer
backbone.
[0099] In some embodiments, R is --H. In some embodiments, R is
--CH.sub.3. In some embodiments, A is O. In some embodiments, A is
NH. In some embodiments, B is C.sub.2 alkylenyl (i.e.
--CH.sub.2--CH.sub.2--). In some embodiments, B comprises at least
one ethylene glycol (i.e. --O--CH.sub.2--CH.sub.2--O--) or
propylene glycol (i.e. --O--CH.sub.2--CH.sub.2--CH.sub.2--O--)
moiety. In some embodiments, each R.sup.a is --CH.sub.3.
Z.sup..theta. is any suitable anion, such as a halide (e.g.,
fluoride, chloride, bromide or iodide), acetate, benzenesulfonate,
benzoate, bicarbonate, nitrate, methanesulfonate,
p-toluenesulfonate, or the like. In some embodiments, Z.sup..theta.
is chloride or methanesulfonate.
[0100] Exemplary hydrolyzable monomer units that include positively
charged moieties are N,N-dimethylaminoethyl acrylate methyl
chloride quaternary salt (DMAEA.MCQ), N,N-dimethylaminoethyl
methacrylate methyl chloride quaternary salt (DMAEM.MCQ),
N,N-dimethylaminopropyl acrylamide methyl chloride quaternary salt,
and N,N-dimethylaminopropyl methacrylamide methyl chloride
quaternary salt.
As an example of a hydrolyzable ionic cross-link, a monomer unit
that is a DMAEA.MCQ or DMAEM.MCQ monomer unit may interact with an
acrylate monomer unit to form an ionic cross-link. The ester moiety
of the DMAEA.MCQ or DMAEM.MCQ may undergo hydrolysis to release the
positively charged quaternary salt group, thereby breaking the
cross-link.
[0101] Ionically cross-linked polymers may be prepared by
polymerizing a mixture of monomers, which includes monomers bearing
a charged hydrolyzable moiety, and monomer units bearing an
opposite charge. For example, a polymer may be prepared by
polymerizing a mixture comprising acrylamide monomers, acrylate
monomers (e.g., sodium acrylate), and monomers having the following
formula (Ia):
##STR00006##
wherein:
[0102] R is selected from the group consisting of --H,
C.sub.1-C.sub.24 alkyl, C.sub.2-C.sub.24 alkenyl and
C.sub.2-C.sub.24 alkynyl;
[0103] each R.sup.a is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.50 alkyl,
optionally substituted C.sub.2-C.sub.50 alkenyl, optionally
substituted C.sub.2-C.sub.50 alkynyl and optionally substituted
aryl;
[0104] A is selected from the group consisting of O, S and
NR.sup.b;
[0105] R.sup.b is selected from the group consisting of --H,
optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0106] B is selected from the group consisting of optionally
substituted C.sub.1-C.sub.24 alkylenyl, optionally substituted
C.sub.2-C.sub.24 alkenylenyl, optionally substituted
C.sub.2-C.sub.24 alkynylenyl and optionally substituted
C.sub.2-C.sub.24 heteroalkylenyl; and
[0107] Z.sup..theta. is an anion.
[0108] In some embodiments, R is --H. In some embodiments, R is
--CH.sub.3. In some embodiments, A is O. In some embodiments, A is
NH. In some embodiments, B is C.sub.2 alkylenyl (i.e.
--CH.sub.2--CH.sub.2--). In some embodiments, B comprises at least
one ethylene glycol (i.e. --O--CH.sub.2--CH.sub.2--O--) or
propylene glycol (i.e. --O--CH.sub.2--CH.sub.2--CH.sub.2--O--)
moiety. In some embodiments, each R.sup.a is --CH.sub.3.
Z.sup..theta. is any suitable anion, such as a halide (e.g.,
fluoride, chloride, bromide or iodide), acetate, benzenesulfonate,
benzoate, bicarbonate, nitrate, methanesulfonate,
p-toluenesulfonate, or the like. In some embodiments, Z.sup..theta.
is chloride or methanesulfonate.
[0109] Following polymerization to produce the ionically
cross-linked polymer, the positively charged monomer units derived
from the monomers of formula (Ia) will interact ionically with
negatively charged monomer units derived from the acrylate
monomers, to generate the ionic cross-link. When included in a
water-soluble polymer, ionic cross-linked monomer units may be
present in the polymer at an amount of about 1 mol % to about 25
mol %, or about 1 mol % to about 10 mol %, of the total monomer
units in the polymer. For example, ionic cross-linked monomer units
may be included in the polymer at an amount of about 1 mol %, 2 mol
%, 3 mol %, 4 mol %, 5 mol %, 6 mol %, 7 mol %, 8 mol %, 9 mol %,
10 mol %, 11 mol %, 12 mol %, 13 mol %, 14 mol %, 15 mol %, 16 mol
%, 17 mol %, 18 mol %, 19 mol %, 20 mol %, 21 mol %, 22 mol %, 23
mol %, 24 mol %, or 25 mol % of the total monomer units in the
polymer.
[0110] (2) Hydrolyzable Covalent Cross-Links
[0111] The polymers may include monomer units that are cross-linked
via a covalent hydrolyzable cross-linker. As an example of a
hydrolyzable covalent cross-linking, two monomer units may be
cross-linked via a moiety that includes at least one hydrolyzable
group such as an ester, carbonate, oxalate, acetal, hemiacetal,
hemiaminal, or the like. The cross-linking moiety may include up to
about 1000 member atoms, and may include linear and/or branched
chains, ring structures, and optional substituents. Any suitable
moiety capable of cross-linking two monomer units and having at
least one hydrolyzable group may be used.
[0112] For example, the covalently cross-linked monomer units may
have the following formula (II):
##STR00007##
wherein:
[0113] each X is selected from the group consisting of O, S and
NR.sup.b;
each R.sup.b is independently selected from the group consisting of
--H, optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0114] each R is independently selected from the group consisting
of --H, optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl;
[0115] Y is selected from a group consisting of a bond and a linker
comprising 1 to about 100 member atoms; and
[0116] each represents a point of attachment to a first polymer
backbone, and each represents a point of attachment to the first
polymer backbone or a second polymer backbone.
[0117] In some embodiments, each X is O. In some embodiments, each
X is NH. In some embodiments, Y is a bond. In some embodiments, Y
is a C.sub.1-C.sub.30 alkylenyl group. In some embodiments, Y
comprises at least one oxalate group. In some embodiments, Y
comprises at least one carbonate group. In some embodiments, Y
comprises at least one ethylene glycol moiety (i.e.
--OCH.sub.2CH.sub.2O--). In some embodiments, Y comprises at least
one propylene glycol moiety (i.e.
--OCH.sub.2CH.sub.2CH.sub.2O--).
[0118] For example, the covalently linked monomer units of formula
(II) may have any of the following formulae:
##STR00008##
wherein each m is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12; each n
is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30; each p is 0
or 1; each R is independently selected from the group consisting of
--H and --CH.sub.3; and each R.sup.1 is independently selected from
the group consisting of --H and C.sub.1-C.sub.12 alkyl. The
covalently linked monomer units may have the following formula
(IIa):
##STR00009##
wherein:
[0119] each R is independently selected from the group consisting
of --H and --CH.sub.3;
[0120] Z is selected from the group consisting of a bond and a
C.sub.1-C.sub.12 alkylenyl group; and
[0121] each represents a point of attachment to a first polymer
backbone, and each represents a point of attachment to the first
polymer backbone or a second polymer backbone.
[0122] In an embodiment of formula (IIa), the covalently linked
monomer units may have the following formula (IIb):
##STR00010##
[0123] Other examples of cross-linked monomer units include those
having phenylene groups, quaternary amine groups, carbonate groups,
and the like. For example, covalently linked monomer units may have
any of the following formulae:
##STR00011##
[0124] Other examples of cross-linked monomer units include those
that provide more than two points of attachment to the backbone of
the polymer chain. Examples of such cross-linked monomer units
include the following:
##STR00012##
[0125] The above-identified cross-linked monomer units may be
generated in a number of different ways. For example, two
acrylamide or methacrylamide monomer units may be cross-linked by
adding a dialdehyde compound to a solution of the polymer. Suitable
dialdehyde compounds include but are not limited to glyoxal,
glutaraldehyde, starch dialdehyde, or any compound having two or
more aldehyde groups.
[0126] Alternatively, monomer units of the polymer may be
cross-linked during the synthesis of the polymer, by including in
the polymerization reaction a monomer having the following formula
(III):
##STR00013##
[0127] each X is selected from the group consisting of O, S and
NR.sup.b;
[0128] each R.sup.b is independently selected from the group
consisting of --H, optionally substituted C.sub.1-C.sub.24 alkyl,
optionally substituted C.sub.2-C.sub.24 alkenyl and optionally
substituted C.sub.2-C.sub.24 alkynyl;
[0129] each R is independently selected from the group consisting
of --H, optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl; and
[0130] Y is selected from a group consisting of a bond and a linker
comprising 1 to about 100 member atoms.
[0131] The monomer of formula (III) may be formed immediately prior
to the polymerization process, e.g., by adding a dialdehyde
compound to a solution of an acrylamide or methacrylamide monomer
immediately prior to the polymerization reaction. Alternatively,
the monomer of formula (III) may be prepared in situ by adding a
dialdehyde compound to a reaction mixture during the polymerization
reaction.
[0132] An exemplary monomer unit may have the following formula
(IIIa):
##STR00014##
wherein:
[0133] each R is independently selected from the group consisting
of --H, optionally substituted C.sub.1-C.sub.24 alkyl, optionally
substituted C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl; and
[0134] L is selected from the group consisting of a bond and an
optionally substituted C.sub.1-C.sub.12 alkylenyl group.
[0135] A particular example of a compound that can be included
during synthesis of the polymer is
N,N'-(1,2-dihydroxyethylene)bisacrylamide, also known as glyoxal
bis(acrylamide). Glyoxal bis(acrylamide) may be added to the
polymerization reaction, or it may be formed immediately prior to
or during the polymerization process, by, for example, the addition
of glyoxal to the polymerization reaction.
[0136] As another example, a direct hydrolyzable covalent bond may
form between two monomer units. In such examples, a polymer having
an acrylamide or methacrylamide monomer unit and an acrolein
monomer unit may undergo a reaction to form a covalent bond, e.g.,
as follows:
##STR00015##
wherein:
[0137] R is selected from the group consisting of --H, optionally
substituted C.sub.1-C.sub.24 alkyl, optionally substituted
C.sub.2-C.sub.24 alkenyl and optionally substituted
C.sub.2-C.sub.24 alkynyl, and each represents a point of attachment
to a first polymer backbone, and each represents a point of
attachment to the first polymer backbone or a second polymer
backbone.
[0138] In some embodiments, R is selected from the group consisting
of --H and --CH.sub.3.
[0139] In embodiments in which hydrolyzable covalently cross-linked
monomer units are included in a polymer, either by including a
bifunctional hydrolyzable monomer unit in the polymerization such
as a compound of formula (III), or by adding a dialdehyde compound
as a cross-linker, the crosslinked monomer units may be included in
a polymer in an amount of about 0.1 ppm to about 20000 ppm based on
the weight of the polymer. For example, the cross-linked monomer
units may be included in a polymer in an amount of about 0.1 ppm to
about 10000 ppm, about 0.1 ppm to about 5000 ppm, about 0.1 ppm to
about 1000 ppm, or about 0.1 ppm to about 100 ppm. For example, the
cross-linked monomer units may be included in a polymer in an
amount of about 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.4 ppm, 0.5 ppm, 0.6
ppm, 0.7 ppm, 0.8 ppm, 0.9 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm,
6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm,
60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm,
500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 2000 ppm,
3000 ppm, 4000 ppm, 5000 ppm, 6000 ppm, 7000 ppm, 8000 ppm, 9000
ppm, 10000 ppm, 11000 ppm, 12000 ppm, 13000 ppm, 14000 ppm, 15000
ppm, 16000 ppm, 17000 ppm, 18000 ppm, 19000 ppm, or 20000 ppm.
[0140] (3) Methods of Synthesis
[0141] The water-soluble polymers can be synthesized by any means
known in the art, such as, for example, radical polymerization. For
example, representative polymers can be prepared by the free
radical polymerization of acrylamide and other vinyl monomers,
including, optionally, a hydrolyzable crosslinking monomer (e.g., a
compound of formula (Ia), or a compound of formula (III) or (IIIa),
such as glyoxal bis(acrylamide)). Other additives can optionally be
added, including ones that can form the desired hydrolyzable
crosslinks in the polymer prior to, during, or after the
polymerization reaction.
[0142] In a typical synthesis, the monomer(s) are dissolved in
water and the pH of the monomer solution is adjusted to a target
level. The monomer solution is then purged with an inert gas such
as nitrogen in order to remove all traces of oxygen, which would
otherwise inhibit the free radical polymerization reaction.
Optionally, the monomer solution can be suspended in an emulsion
formed by the addition of a water-immiscible solvent such as a
hydrocarbon oil, along with emulsifying surfactants such as
sorbitan monooleate and/or ethoxylated sorbitan monostearates.
Polymerization is then initiated via the addition of a small amount
of a free radical initiator. The free radical initiators generally
decompose to generate free radicals by thermal, photochemical,
redox, or hybrid mechanisms. Examples of thermal initiators
include, but are not limited to, azo compounds such as
2,2'-azobisisobutryonitrile. Examples of redox initiators include,
but are not limited to, t-butylhydroperoxide/ferrous ion and
ammonium persulfate/sodium bisulfite. The polymerization reaction
is most often conducted between the temperatures of about
10.degree. C. and about 110.degree. C.
[0143] Once the polymerization reaction is completed, an optional
step may be performed in order to reduce the residual monomer
content of the product. This is accomplished, when desired, by
means of heating the reaction product for an additional time
period, or by the addition of additional initiators or other
additives that will react with the residual monomer, or by a
combination of both means. Additional processing steps can be
optionally performed in order to, for example, adjust the product
pH, or remove water or other solvents from the reaction product in
order to produce a solid polymer product. The final polymer product
form is thus dictated by the choice of the formula and the
processing steps employed, so that a polymer product comprised of a
liquid solution, a liquid emulsion, or a dry solid may be
produced.
[0144] In an exemplary embodiment of formula (IIIa), the
hydrolyzable crosslinker structure shown is comprised of a
glyoxal-derived moiety and two acrylamide-derived moieties. This
type of hydrolysable crosslink can be produced in the polymer by a
variety of means, since the reaction used to form the crosslink can
be carried out under reversible reaction conditions. For example,
glyoxal bis(acrylamide) monomer, formed by a separate reaction
between glyoxal and acrylamide, can be added as a comonomer to the
polymerization reaction. Alternatively, glyoxal bis(acrylamide) can
be formed in the polymerization reaction mixture immediately prior
to polymerization, by the addition of glyoxal to the
acrylamide-containing monomer reaction solution, under appropriate
conditions. Alternatively, glyoxal can be added to the final
reaction product after the polymerization reaction, where it can be
expected to react with the polymer to form the desired hydrolyzable
crosslinks, under the appropriate conditions. One skilled in the
art would recognize that any compound that generates glyoxal under
these reaction conditions could also be used in place of glyoxal in
these reactions. Such compounds include, but are not limited to,
hydrolyzable polymers containing glyoxal, adducts formed from
glyoxal and amines, adducts formed from glyoxal and amides, or
acetals formed from glyoxal.
[0145] b. Viscosity
[0146] Prior to activation, a first polymer composition may have a
viscosity of about 0 cPs to about 100 cPs. For example, the first
polymer composition may have a viscosity of about 0 cPs, 0.001 cPs,
0.01 cPs, 0.1 cPs, 0.2 cPs, 0.3 cPs, 0.4 cPs, 0.5 cPs, 0.6 cPs, 0.7
cPs, 0.8 cPs, 0.9 cPs, 1 cPs, 2 cPs, 3 cPs, 4 cPs, 5 cPs, 6 cPs, 7
cPs, 8 cPs, 9 cPs, 10 cPs, 15 cPs, 20 cPs, 25 cPs, 30 cPs, 35 cPs,
40 cPs, 45 cPs, 50 cPs, 55 cPs, 60 cPs, 65 cPs, 70 cPs, 75 cPs, 80
cPs, 85 cPs, 90 cPs, 95 cPs or 100 cPs. In some embodiments, a
first polymer composition may have a viscosity of about 0.001 cPs
to about 100 cPs. In some embodiments, a first polymer composition
may have a viscosity of about 0.01 cPs to about 100 cPs. In some
embodiments, a first polymer composition may have a viscosity of
about 0.1 cPs to about 20 cPs. In some embodiments, a first polymer
composition may have a viscosity of about 0.1 cPs to about 10
cPs.
[0147] After exposure to a stimulus or a change in conditions such
as temperature, pH, concentration, ionic strength or the like, the
viscosity of the activated polymer composition may be about the
same or higher than a viscosity of the first polymer composition
prior to the stimulus, or the viscosity may be about the same or
higher than the viscosity of an first polymer composition
comprising a corresponding water-soluble polymer that lacks the
hydrolyzable cross-links. For example, after activation, the
activated polymer composition may have a viscosity of about 1 cPs
to about 5000 cPs, e.g., 1 cPs, 5 cPs, 10 cPs, 20 cPs, 30 cPs, 40
cPs, 50 cPs, 60 cPs, 70 cPs, 80 cPs, 90 cPs, 100 cPs, 150 cPs, 200
cPs, 250 cPs, 300 cPs, 350 cPs, 400 cPs, 450 cPs, 500 cPs, 550 cPs,
600 cPs, 650 cPs, 700 cPs, 750 cPs, 800 cPs, 850 cPs, 900 cPs, 950
cPs, 1000 cPs, 1100 cPs, 1200 cPs, 1300 cPs, 1400 cPs, 1500 cPs,
1600 cPs, 1700 cPs, 1800 cPs, 1900 cPs, 2000 cPs, 2100 cPs, 2200
cPs, 2300 cPs, 2400 cPs, 2500 cPs, 2600 cPs, 2700 cPs, 2800 cPs,
2900 cPs, 3000 cPs, 3100 cPs, 3200 cPs, 3300 cPs, 3400 cPs, 3500
cPs, 3600 cPs, 3700 cPs, 3800 cPs, 3900 cPs, 4000 cPs, 4100 cPs,
4200 cPs, 4300 cPs, 4400 cPs, 4500 cPs, 4600 cPs, 4700 cPs, 4800
cPs, 4900 cPs, or 5000 cPs.
[0148] c. Additional Components
[0149] In addition to the water-soluble polymer, the first polymer
composition and/or the activated polymer composition may optionally
include one or more further additives. Such papermaking additives
include, for example, other retention aids (e.g., microparticles,
flocculants, polymeric and inorganic coagulants, etc.), wet and dry
strength additives (e.g., cationic starches, polyamidoamine
epichlorohydrin-based polymers), fillers, dyes, optical brightening
agents, sizing agents, fixatives, detackifiers, dispersants, the
like, and combinations of the foregoing.
3. EXAMPLES
[0150] The foregoing may be better understood by reference to the
following examples, which are presented for purposes of
illustration and are not intended to limit the scope of the
invention. All reagents were purchased from commercial sources and
used as received unless stated otherwise.
N,N'-(1,2-dihydroxyethylene)bisacrylamide, also known as glyoxal
bis(acrylamide) is abbreviated herein as GBA.
Example 1
Synthesis of Polymers 1a, 1b, 1c and 1d
[0151] Polymer 1a includes of 29 mole percent sodium acrylate, 71
mole percent acrylamide, and 3.5 ppm GBA hydrolyzable crosslinker
(based on the total formula). The polymer was prepared by
polymerizing a monomer emulsion consisting of an aqueous mixture of
25.0 g of 50% acrylamide, 5.39 g of acrylic acid, 16.00 g water,
neutralized with 5.90 g 50% aqueous sodium hydroxide. In addition,
0.006 g of tetrasodium diethylenediaminetetraaacetate, and 0.026 g
of a freshly-prepared 1% aqueous solution of
(1,2-dihydroxyethylene)bisacrylamide (GBA) were added to the
aqueous monomer solution The aqueous monomer solution was dispersed
in an oil phase comprised of a solution of 21.00 g petroleum
distillate, 1.0 g sorbitan monooleate and 0.61 g ethoxylated
sorbitan monostearate.
[0152] The monomer emulsion was prepared by mixing the aqueous
phase and the oil phase under shear for 30-60 minutes, followed by
deoxygenation with nitrogen for 30 minutes. Polymerization is
initiated by adding 2,2'-azobisisobutryonitrile at a reaction
temperature of 45.degree. C. The reaction temperature of the
polymerization is maintained at 45.degree. C. for 4 hours, then
heated to 57.degree. C. for an additional hour.
[0153] Dissolution of the polymer emulsion in water was effected by
mixing the emulsion into a large volume of water under shear, in
the presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
[0154] The above procedure was also repeated at 1 kg and 2.4 kg
scales, providing polymers 1b and 1c, respectively. Polymer 1d was
prepared similarly.
Example 2
Preparation of Polymer 2
[0155] Polymer 2 was prepared by polymerizing a monomer emulsion
consisting of an aqueous mixture of 24.9 g of 50% acrylamide, 4.6 g
of N,N-dimethylaminoethyl acrylate methyl-chloride quaternary salt,
10.2 g water, neutralized with 0.078 g 50% aqueous sodium
hydroxide. In addition, 0.006 g of tetrasodium
diethylenediaminetetraaacetate, 0.54 g Adipic Acid, 1.79 g sodium
chloride, 0.60 g urea, and 0.213 g of a freshly-prepared 0.1%
aqueous solution of GBA were added to the aqueous monomer solution.
The aqueous monomer solution was dispersed in an oil phase
comprised of a solution of 15.57 g petroleum distillate, 0.73 g
sorbitan monooleate and 0.73 g ethoxylated sorbitan monostearate.
If necessary the monomer phase pH was adjusted to .about.4 using
50% aqueous sodium hydroxide or concentrated hydrochloric acid.
[0156] The monomer emulsion was prepared by mixing the aqueous
phase and the oil phase under shear for 30-60 minutes, followed by
deoxygenation with nitrogen for 30 minutes. Polymerization was
initiated by adding 0.0095 g 2,2'-azobisisobutryonitrile and 0.0012
g 2,2'-Azobis (2,4-Dimethyl Valeronitrile) at a reaction
temperature of 45.degree. C. The reaction temperature of the
polymerization was maintained at 45.degree. C. for 3 hours, then
heated to 70.degree. C. for an additional hour.
[0157] Dissolution of the polymer emulsion in water was effected by
mixing the emulsion into a large volume of water under shear, in
the presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
Example 3
Preparation of Polymers 3a, 3b and 3c
[0158] Polymer 3a was prepared by polymerizing a monomer emulsion
consisting of an aqueous mixture of 381.375 g of 50.20% acrylamide,
78.730 g of acrylic acid, and 178.050 g water which was neutralized
in an ice-bath with 50% aqueous sodium hydroxide (86.500 g). In
addition, 0.300 g of a freshly-prepared 2% aqueous solution of
glyoxal was added to the aqueous monomer solution. The aqueous
monomer solution was warmed and stirred for period sufficient for
the required (1,2-dihydroxyethylene)bisacrylamide (GBA) to be
formed in situ. 0.090 g Of tetrasodium
diethylenediaminetetraaacetate was then added to the prepared
monomer phase.
[0159] The aqueous monomer solution was then dispersed in an oil
phase comprised of a solution of 253.350 g petroleum distillate,
12.220 g sorbitan monooleate, and 7.300 g ethoxylated sorbitan
monostearate.
[0160] The monomer emulsion was prepared by mixing the aqueous
phase and the oil phase under shear for 30-60 minutes, followed by
addition of 0.528 g of 2,2'-azobisisobutryonitrile and nitrogen
purging. The reaction temperature of the polymerization was
maintained at 44.degree. C. for 3.5 hours with nitrogen purging and
then heated to 57.degree. C. for an additional hour.
Dissolution of the polymer emulsion in water is affected by mixing
the emulsion into a large volume of water under shear, in the
presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
[0161] Polymers 3b and 3c were prepared following the same
procedure using different levels of glyoxal in the formula: 0.600 g
of a 2% glyoxal solution for 3b and 1.200 g of a 2% glyoxal
solution for 3c.
Example 4
Preparation of Polymer 4
[0162] Polymer 4 was prepared by first preparing a 30 mol % sodium
acrylate acrylamide emulsion copolymer using a similar method to
Example 1, followed by post-treatment with glyoxal. A 100 g sample
of a 30 mol % sodium acrylate acrylamide emulsion copolymer was
treated under shear with 0.032 g of a 40% glyoxal solution. The
mixture was stirred 15 minutes at 25.degree. C. then stored without
agitation for 24 hours at 40.degree. C.
[0163] Dissolution of the polymer emulsion in water was affected by
mixing the emulsion into a large volume of water under shear, in
the presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
Example 5
Preparation of Polymer 5
[0164] Polymer 5, a temporary ionic crosslinked emulsion polymer,
was prepared by polymerizing a monomer emulsion consisting of an
aqueous mixture of 25.00 g of 50% acrylamide, 4.30 g of acrylic
acid, 16.21 g water, neutralized with 4.3 g 50% aqueous sodium
hydroxide. In addition, 3.70 g of an 80% solution of
N,N-dimethylaminoethyl acrylate, methyl chloride quaternary salt
and 0.007 g of tetrasodium diethylenediaminetetraaacetate were
added to the aqueous monomer solution. The aqueous monomer solution
was then dispersed in an oil phase comprised of a solution of 21.00
g petroleum distillate, 1.01 g sorbitan monooleate, and 0.61 g
ethoxylated sorbitan monostearate.
[0165] The monomer emulsion was prepared by mixing the aqueous
phase and the oil phase under shear for 30-60 minutes, followed by
deoxygenation with nitrogen for 30 minutes. Polymerization is
initiated by adding 0.038 g 2,2'-azobisisobutryonitrile at a
reaction temperature of 45.degree. C. The reaction temperature of
the polymerization is maintained at 45.degree. C. for 4 hours and
then heated to 58.degree. C. for an additional hour.
[0166] Dissolution of the polymer emulsion in water was effected by
mixing the emulsion into a large volume of water under shear, in
the presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
Example 6
Preparation of Polymer 6
[0167] Polymer 6, a diester crosslinked emulsion polymer, was
prepared by polymerizing a monomer emulsion consisting of an
aqueous mixture of 25.00 g of 50% acrylamide, 5.39 g of acrylic
acid, 15.22 g water, neutralized with 5.90 g 50% aqueous sodium
hydroxide. In addition, 0.784 g of a 0.1% solution of
tetraethyleneglycol diacrylate crosslinker and 0.007 g of
tetrasodium diethylenediaminetetraaacetate were added to the
aqueous monomer solution. The aqueous monomer solution was then
dispersed in an oil phase comprised of a solution of 19.00 g
petroleum distillate, 0.917 g sorbitan monooleate, and 0.55 g
ethoxylated sorbitan monostearate.
[0168] The monomer emulsion was prepared by mixing the aqueous
phase and the oil phase under shear for 30-60 minutes, followed by
deoxygenation with nitrogen for 30 minutes. Polymerization is
initiated by adding 0.038 g 2,2'-azobisisobutryonitrile at a
reaction temperature of 45.degree. C. The reaction temperature of
the polymerization is maintained at 45.degree. C. for 4 hours, then
heated to 58.degree. C. for an additional hour.
[0169] Dissolution of the polymer emulsion in water was effected by
mixing the emulsion into a large volume of water under shear, in
the presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the emulsion polymer.
Example 7
Polymer Activation Procedures
[0170] The temporary-crosslinked polymers were activated in order
to hydrolyze the temporary crosslinks and increase the solution
viscosity of the polymer solutions derived from them. This can be
accomplished by heating, or by changing the pH, or by a combination
of heat and pH, for a specified time period. The polymers can be
activated either in the emulsion product form, or after make down
of the emulsion to produce dilute polymer solutions. Activation of
the polymers in the emulsion product form, during the manufacture
of the emulsion polymer product, is preferred. Typical procedures
are provided here for Polymers 7a and 7b. For polymer 7a, the
crosslinked emulsion polymer described in Example 1c was heated for
three hours at 70.degree. C. after the polymerization reaction was
completed. For polymer 7b, the crosslinked emulsion polymer
described in Example 1c was pH-adjusted by the addition of 0.5 wt.
% sodium carbonate after the polymerization reaction was completed,
and then heated for 3 hours at 70 C. The Table below describes the
viscosities of the polymer solutions before (polymer 1c) and after
activation (polymers 7a and 7b). The viscosities were measured
after the polymers were dissolved in 3.5 wt. % synthetic sea water
at 3000 ppm polymer concentration by mixing the emulsion polymer
into a large volume of synthetic sea water under shear, in the
presence of a high HLB nonionic surfactant at a level less than
about 5% of the weight of the polymer. The bulk viscosities of the
polymer solutions were measured at a shear rate of 10.2 s.sup.-1.
Viscosities are presented in Table 1.
TABLE-US-00001 TABLE 1 Activation or Removal of the Temporary
Crosslinks in the Polymer Unactivated Polymer 1c Activated Polymer
Polymer viscosity 7 viscosities Activation Procedure Polymer 7a
1.56 110.19 Heat polymer emulsion for 3 h at 70.degree. C. with
mixing Polymer 7b 1.56 133.64 Raise pH above 8 with 0.5%
Na.sub.2CO.sub.3 and heat polymer emulsion for 3 h at 70.degree. C.
with mixing
Example 8
First Pass Retention Test
[0171] The first pass retention test used a Britt CF Dynamic
Drainage Jar having an upper chamber of about 1 liter capacity and
a bottom drainage chamber, the chamber being separated by a support
screen and a drainage screen. Below the drainage chamber was a
downward extending flexible tube equipped with a clamp for closure.
The upper chamber was provided with a variable speed, high torque
motor equipped with a 2-inch 3-bladed propeller to create
controlled shear conditions in the upper chamber. The test was
conducted by placing a cellulosic slurry in the upper chamber and
then subjecting the slurry to the following sequences:
TABLE-US-00002 Sequence for Evaluating Polymer Performance Time
(seconds) Action 0 Commence shear stirring at 1250 rpm 5 Add starch
and coagulant (when necessary) 20 Add polymer 30 Start draining 60
Stop draining; analyze filtrate
[0172] The material drained from the Britt jar (the "filtrate") was
collected and filtered through a glass fiber filter pad with a
nominal pore diameter of one micron. The filter pad and filtrate
were then dried at 105.degree. C. for 12 hours and the dry mass of
the filtrate was determined. The first pass retention value was
calculated using the formula:
First Pass Retention ( % ) = ( Cellulosic slurry consistency -
Filtrate consistency Cellulosic slurry consistency ) .times. 100
##EQU00002##
[0173] Cellulosic slurry comprised solids which are made up of
about 80 weight percent fiber and 20 weight percent filler, diluted
to an overall consistency of 0.5 percent with formulation water.
The fiber was a 60/40 blend by weight of bleached hardwood kraft
(sulfate chemical pulp) and bleached softwood kraft (sulfate
chemical pulp). To this slurry was added a mineral filler, namely a
commercial calcium carbonate provided in dry form. The formulation
water contained 60 ppm calcium hardness (added as CaCl.sub.2), 18
ppm magnesium hardness (added as MgSO.sub.4) and 134 ppm
bicarbonate alkalinity (added as NaHCO.sub.3). The pH of the final
thin stock (cellulosic slurry plus filler and other additives
equals a "stock") was between about 7.5 and about 8.0.
[0174] Results are illustrated in Table 2 below, and graphically in
FIGS. 1-3. The "New polymer" corresponds to polymer 7b as described
in Example 7. The "Reference Polymer" is a high molecular weight 30
mol % anionic linear polymer with a RSV value between 38 dL/g and
49 dl/g. The polymer is an acrylamide/sodium acrylate copolymer to
which no crosslinker was added.
TABLE-US-00003 TABLE 2 First Pass Retention Results Using Britt Jar
Apparatus in Nalco Standard Alkaline Furnish with Increased
Precipitated Calcium Carbonate Content Polymer Dosage (lb/ton
furnish Reference Polymer New Polymer solids) Test 1 Test 2 Test 3
Test 1 Test 2 Test 3 0.125 x 81.97 79.77 x 82.57 80.98 0.25 81.75
84.97 82.16 82.65 86.29 83.77 (.+-.0.83) (.+-.1.09) (.+-.1.20)
(.+-.1.11) 0.5 85.41 88.54 85.58 87.03 90.70 87.87 (.+-.0.48)
(.+-.0.53) (.+-.0.47) (.+-.1.76) 1 90.22 x x 93.13 x x Values in (
) represent the 90% confidence intervals for the data collected
[0175] FIG. 4 is a graphical representation of the data used to
calculate an average replacement ratio. This was performed by
selecting a first pass retention value (such as 85%) then using
data trend lines fit using polynomial curves to the data points the
corresponding dosages for each polymer were calculated. The
percentage reduction in dosage from using the new polymer relative
to the reference polymer was then calculated. If this was done for
first pass retention values of 80%, 85%, and 90% and the
replacement ratios were averaged. The use of polymer 7b results in
approximately a 23% reduction in dosage to get equal performance
compared to the reference polymer.
[0176] It is understood that the foregoing detailed description and
accompanying examples are merely illustrative and are not to be
taken as limitations upon the scope of the invention, which is
defined solely by the appended claims and their equivalents.
[0177] Various changes and modifications to the disclosed
embodiments will be apparent to those skilled in the art. Such
changes and modifications, including without limitation those
relating to the chemical structures, substituents, derivatives,
intermediates, syntheses, compositions, formulations, or methods of
use of the invention, may be made without departing from the spirit
and scope thereof.
* * * * *