Note: Descriptions are shown in the official language in which they were submitted.
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
PAPERMAKING AND PRODUCTS MADE THEREBY WITH HIGH SOLIDS
GLYOXALATED-POLYACRYLAMIDE AND SILICON-CONTAINING MICROPARTICLE
BACKGROUND OF THE INVENTION
[00011 This application claims the benefit under 35 U.S.C. 119(e) of prior
U.S. Provisional
Patent Application No. 61/221,107, filed June 29, 2009, which is incorporated
in its entirety by
reference herein.
[00021 The present invention relates to papermaking, and more particularly, to
papermaking
and products made thereby with high solids glyoxalated polyacrylamide and
silicon-containing
microparticles.
[00031 In the production of paper and paperboard from a dilute aqueous
suspension of
cellulose fibers on papermaking apparatus, the suspension can be passed
through one or more
shear stages and the resultant suspension is drained through a wire to form a
sheet, which is then
dried. Process improvements have been sought in the past, for example, in
retention, drainage,
and drying, and in the formation (or structure) properties of the final paper
sheet. Retention is a
term used in papermaking to indicate the extent to which the pulp fibers and
other additives
which are added to the furnish are retained in the finished paper. A retention
aid generally acts by
increasing the flocculating tendency of the pulp fibers and additives to
inhibit their loss during
drainage through the paper machine wires or screens. Drainage or de-watering
is another
papermaking requirement.
[00041 U.S. Pat. No. 3,556,932 relates to glyoxalated polyacrylamide that can
be prepared by
reacting glyoxal with a cationic polyacrylamide under slightly alkaline
conditions and its
application to increase paper wet strength. Sodium bisulfite is used as an
anti-gelation agent. The
cationic polyacrylamide (base polymer) has a molecular weight of 7000 - 25,000
Daltons. The
1
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
cationic charge is obtained by copolymerizing acrylamide with a cationic
monomer, which is
typically dimethyldiallylammonium chloride. The basepolymer is exemplified in
U.S. Pat. No.
3,556,932 as having a molecular weight below 25,000 Daltons and an acrylamide:
DADMAC
molar ratio of 99:1 to 75:25.
[0005] WO 2006/068964 relates to a reactive cationic resin for use as dry and
wet strength
agents in sulfite ion-containing papermaking systems. The cationic resin
includes a dialdehyde
reactive copolymer wherein the cationic co-monomer has greater than 10 mole%
of the
dialdehyde reactive copolymer before reaction with dialdehyde. WO 2006/068964
also relates to
a process for making paper in which the above cationic resin was added to an
aqueous pulp
suspension containing a sulfite level in excess of 20 ppm.
[0006] WO 2008/157321 relates to storage-stable glyoxalated polyacrylamide
polymers and
high solids aqueous compositions formulated with them, which can be used as
additives for
papermaking, providing paper with good dry and temporary wet strength, and
increasing
papermaking de-watering rates.
[0007] U.S. Pat. No. 4,961,825 relates to production of paper or pulp sheets
from a paper
stock with a binder added which comprises cationic and anionic components. The
anionic
component consists of colloidal anionic particles having at least one surface
layer of aluminum
silicate or aluminum-modified silicic acid, such that the surface groups of
the particles contain
silicon and aluminum atoms in a ratio of from 9.5:0.5 to 7.5:2.2, and the
cationic component
consists of cationic carbohydrate having a degree of substitution of 0.01-1Ø
[0008] U.S. Pat. No. 5,368,833 relates to silica sols having a high content of
microgel and
aluminum modified particles with high specific area. The sols are said to be
suitable for use as
additives, in combination with cationic polymers, in papermaking.
2
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
[0009] U.S. Pat. No. 5,603,805 relates to silica sols with a high content of
microgel and
particles with a specific surface area within a range of 300 to 700 m2/g. The
sols are said to be
suitable for use as additives in papermaking in combination with cationic
polymers such as
cationic acrylamide based polymers.
[0010] U.S. Pat. No. 4,305,781 relates to methods of making newsprint, Kraft
or fluting
medium from an aqueous suspension of cellulosic fibers, where drainage and
retention properties
of the suspension are said to be improved by including a water soluble high
molecular weight
substantially non-ionic polymer and a bentonite-type clay.
[0011] U.S. Pat. No. 4,753,710 relates to a process in which paper or paper
board is made by
passing an aqueous cellulosic substrate through a centriscreen or other shear
device and then
draining the purified suspension, and an improved combination of retention,
drainage, drying and
formation is said to be achieved by adding to the suspension an excess of high
molecular weight
linear synthetic cationic polymer before shearing the suspension and adding
bentonite after
shearing.
[0012] U.S. Pat. No. 4,388,150 relates to a papermaking process in which an
aqueous
papermaking stock or white water has added a binder comprising colloidal
silicic acid and
cationic starch.
SUMMARY OF THE PRESENT INVENTION
[0013] A feature of the present invention is to provide an enhanced additive
system for
improving wet-end drainage and retention in papermaking using glyoxalated
polyacrylamide ("G-
PAM") polymers and microparticles.
[0014] Another feature of the present invention is to provide increased
papermaking retention
3
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
efficiencies and de-watering rates with a retention/drainage additive system
comprising high
solids glyoxalated polyacrylamide polymer and silicon-containing
microparticles.
[0015] An additional feature of the present invention is to provide decreased
filtrate turbidities
and more rapid drainage rates with an additive system comprising a high solids
glyoxalated
polyacrylamide polymer and silicon-containing microparticles.
[0016] Another feature of the present invention is to provide lowered filtrate
turbidities and
comparable drainage rates as polyamine coagulant products with an additive
system comprising a
high solids glyoxalated polyacrylamide polymer and silicon-containing
microparticles.
[0017] A further feature of the present invention is to provide paper products
containing a
glyoxalated polyacrylamide polymer and silicon-containing microparticles.
[0018] An additional feature of the present invention is to provide a process
for papermaking
which can improve the retention/drainage properties, as well as provide
improvements in dry
strength impact.
[0019] Additional features and advantages of the present invention will be set
forth in part in
the description that follows, and in part will be apparent from the
description, or can be learned by
practice of the present invention. The objectives and other advantages of the
present invention will
be realized and attained by means of the elements and combinations
particularly pointed out in the
description and appended claims.
[0020] To achieve these and other advantages, and in accordance with the
purposes of the
present invention, as embodied and broadly described herein, the present
invention relates, in part,
to a process for making paper, and the products thereof, comprising adding
silicon-containing
microparticles and a glyoxalated polyacrylamide polymer containing at least
about 25% by
weight cationic monomer to an aqueous suspension containing cellulosic fibers,
and forming said
4
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
suspension into a water-laid web and drying said web to form paper. The
silicon-containing
microparticles are added, in combination with the glyoxalated polyacrylamide
polymer, in an
amount effective to increase fiber retention and de-watering rate as compared
to paper made with
the suspension absent the silicon-containing microparticles. The glyoxalated
polyacrylamide
polymer component of the additive system can be introduced, for example, as a
high solids
aqueous composition thereof having a high active polymer concentration, for
example, about
10% by weight or more of the glyoxalated polyacrylamide polymer. The
combination of silicon-
containing microparticles with high solids glyoxalated polyacrylamide polymer
in the wet-end of
a papermaking process can greatly improve retention and drainage performance,
and/or dry
strength impact.
10021] The silicon-containing microparticles can comprise solid microparticles
containing
silicon (Si). The solid microparticles containing silicon can be, for example,
inorganic crystalline
and/or non-crystalline (e.g., amorphous) materials. The microparticles can be
used, for example,
in dry powder form or dispersed form (e.g., suspensions, slurries, colloids,
sols). The silicon-
containing microparticles are selected, for example, from microparticles of
silica, bentonite, or a
combination thereof. The silicon-containing microparticles can comprise, for
example,
amorphous silica microparticles. The silicon-containing microparticles can
comprise, for example,
colloidal silica comprising a surface area from 300 m2/g to 1000 m2/g, 500
m2/g to 800 m2/g, or 600
m2/g to 750 m2/g, and/or an S-value from 80% to 20%, 70% to 30%, or 60% to
40%. The colloidal
silica can optionally be surface modified, such as aluminate-treated, metal-
treated, or untreated. The
silicon-containing microparticles can comprise, for example, bentonite
microparticles. The
bentonite optionally can be chemically modified or untreated. The silicon-
containing
microparticles can have an average particle size, for example, of not greater
than about 1,000 nm,
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
1 mn to 750 nm, 2 nm to 500 nm, 3 nm to 500 nm, 4 nm to 100 nm, 5 nm to 50 nm,
or 10 nm to
30 nm. The silicon-containing microparticles can have an absolute particle
size within one or
more of these size ranges. The dry particle size distribution of the silicon-
containing particles can
be, for example, such that at least 90%, or at least 95%, or at least 99% up
to 100%, have an
absolute particle size of less than 1000 nm, or less than 750 nm, or less than
500 nm, or less than
100 run, or less than 75 nm, or less than 50 nm. The paper made in processes
according to the
present invention can comprise from about 0.05 to about 2.5 pounds (lb.)
silicon-containing
microparticles/ton dry fiber, about 0.1 to about 1 lb. silicon-containing
microparticles/ton dry
fiber, or about 0.2 to about 0.8 lb. silicon-containing microparticles/ton dry
fiber.
[00221 The glyoxalated polyacrylamide polymer can comprise a reaction product
between
glyoxal and a cationic polyacrylamide base polymer, wherein the cationic
polyacrylamide base
polymer can comprise from about 75% to about 10%, by weight, acrylamide
monomer and from
about 25% to about 90%, by weight, cationic monomer copolymerizable with the
acrylamide
monomer, and has sufficient glyoxal-reactive amide substituents and -CHOHCHO
substituents
to be thermosetting. The concentration of the glyoxalated acrylamide polymer
in an aqueous
carrier can be from about 10% to about 30%, by weight, or, from about 11% to
about 15%, by
weight, or, from about 12% to about 15%, by weight, glyoxalated acrylamide
polymer (on an
active solids basis). The paper made in processes according to the present
invention can have the
glyoxalated polyacrylamide polymer added in an amount of from about 0.5 to
about 12 pounds
(lb.) polymer/ton dry fiber, about 1 to about 11 lb. polymer/ton dry fiber, or
about 3 to about 10
lb. polymer/ton dry fiber.
[00231 The glyoxalated acrylamide polymer can comprise, for example, from
about 70% to
about 30%, by weight, acrylamide monomer and from about 30% to about 70%, by
weight,
6
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
cationic monomer, or, for example, from about 65% to about 50%, by weight,
acrylamide
monomer and from about 35% to about 50%, by weight, cationic monomer, or, for
example,
from about 62% to about 55%, by weight, acrylamide monomer and from about 38%
to about
45%, by weight, cationic monomer, and can have sufficient glyoxal-reactive
amide substituents
and -CHOHCHO substituents to be thermosetting. The cationic monomer of the
polymer can be
2-vinylpyridine, 2-vinyl-N-methylpyridinium chloride, (p-vinylphenyl)
trimethyl ammonium
chloride, diallyldimethylammonium chloride, 2-(dimethylamino)ethyl acrylate,
trimethyl(p-
vinylbenzyl)ammonium chloride, p-dimethylaminoethylstyrene,
dimethylaminopropyl
acrylamide, 2-methylacroyloxyethyltrimethyl ammonium methylsulfate, or 3-
acrylamido-3-
methylbutyl trimethyl ammonium chloride, or any combination thereof. The
cationic monomer
can be diallyldimethyl ammonium chloride. The acrylamide monomer can be
replaced by other
primary amide-containing monomers such as methacrylamide, ethylacrylamide,
crotonamide, N-
methyl acrylamide, N-butyl acrylamide, or N-ethyl methacrylamide, or any
combination thereof.
The acrylamide monomer can be acrylamide. The glyoxalated polyacrylamide
polymer can be
the reaction product of glyoxal and a base polymer comprising the acrylamide
monomer and the
cationic monomer in a weight ratio, ranging, for example, from about 0.01 to
about 0.6:1, and,
for example, from about 0.10 to about 0.30:1. The base polymer can have a
molecular weight
(weight average molecular weight) ranging, for example, from about 500 Daltons
to 100,000
Daltons, for example, 3,000 to 20,000 Daltons, for example, from about 3,000
Daltons to about
13,000 Daltons, or, for example, 5,000 Daltons to 9,000 Daltons.
[0024] As part of the present invention, a paper product is provided
comprising the high
solids, higher charged glyoxalated polyacrylamide polymer and silicon-
containing microparticles
of the additive systems of the present invention. Paper products made with the
improved
7
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
retention/drainage additive system according to the present invention have
useful dry and
temporary wet strength performances, and other mechanical properties typically
desired of paper
products. The paper product can comprise, for example, a cellulosic fibrous
non-woven web. A
paper product can comprise a paper layer containing the glyoxalated
polyacrylamide polymer and
silicon-containing microparticles, wherein the product is, for example, paper
sheeting,
paperboard, tissue paper, or wall board. Paper products include, for example,
all grades of paper,
newsprint, linerboard, fluting medium, and Kraft, and other paper materials.
[0025] It is to be understood that both the foregoing general description and
the following
detailed description are exemplary and explanatory only and are intended to
provide a further
explanation of the present invention, as claimed.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0026] The present invention relates, in part, to combinations of glyoxalated
polyacrylamide
polymers and silicon-containing microparticles as co-additives in papermaking
to provide paper
products made with improved drainage and retention. A process is provided for
making paper
comprising adding silicon-containing microparticles and a glyoxalated
polyacrylamide polymer
containing at least about 25% by weight cationic monomer to an aqueous
suspension containing
cellulosic fibers, and forming said suspension into a water-laid web and
drying said web to form
paper. Paper products of the process are also provided. The suspension can
comprise, consist
essentially of, or consist of silicon-containing microparticles, a glyoxalated
polyacrylamide
polymer, and cellulosic fibers.
[0027] Many retention/drainage aids decrease paper dry strength or have no dry
strength
impact in papermaking. However, with the present invention, an increase in dry
strength is
8
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
achievable and, in addition, the retention/drainage can be improved. The dry
strength and/or
retention/drainage can increase 10% or more, 20% or more, 30% or more, as
compared to the
same composition but without a microparticle present with the base polymer
(e.g., G-PAM).
[00281 The use of silicon-containing particle as solid microparticles in
combination with the
high solids glyoxalated polyacrylamide polymers in a wet-end of papermaking,
instead of larger
silicon-containing particles can be important to achieving the unique
retention and drainage
performance. The additional presence of the silicon-containing microparticles
with the high
solids glyoxalated polyacrylamide polymers in a papermaking process according
to the present
invention has been found to preferably have a synergistic effect, wherein the
retention/drainage
performance is increased and/or the dry strength beyond what is obtained with
the same glyoxalated
polyacrylamide polymers alone. Further, the combined use of high solids
glyoxalated
polyacrylamide polymers and silicon-containing microparticles can provide
reduced filtrate
turbidities and/or faster drainage rates than some commercial glyoxalated
polyacrylamide products
when used as commercially supplied or in combination with similar silicon-
containing
microparticles for sake of comparison. The preferred joint improvement in
fiber retention and
drainage rate properties obtained in paper products made with G-PAM/silicon-
containing
microparticle additive systems according to the present invention is
unexpected and surprising. In
addition, the combined use of high solids glyoxalated polyacrylamide polymers
and silicon-
containing microparticles according to the present invention can provide both
reduced filtrate
turbidities and at least comparable drainage rates than some commercial
polyamine coagulant
products when used as commercially supplied or in combination with similar
silicon-containing
microparticles for sake of comparison. The ability to both increase drainage
rates and improve
retention efficiencies allows for more economical production to be obtained,
as, for example,
9
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
production cycles can be accelerated without increasing white water recycling
or handling/disposal
requirements. Further, the combinations of glyoxalated polyacrylamide polymers
and silicon-
containing microparticles according to the present invention also can be
applied to reduce other
additive requirements of the papermaking process. For example, the high solids
G-PAM
compositions of the combination can multi-task to replace both conventional G-
PAM products used
as dry strength resin and also conventional polyamine products used as
coagulant.
[00291 The process according to the present invention can be practiced on
conventional
papermaking machines, such as a Fourdrinier type paper machine, with
modifications that can be
made in view of the present invention. The glyoxalated polyacrylamide polymers
and silicon-
containing microparticles can be added at the wet-end of a paper-making
facility to the dilute
cellulose fiber suspensions for the enhancement of water removal and retention
of fine particles
during papermaking. The glyoxalated polyacrylamide polymers and silicon-
containing
microparticles components can be added to the papermaking machine as a pre-
mixture with each
other, or separately in any order of addition. The components can be added as
separate batches,
as combined batches, sequentially, continuously, semi-continuously, or
periodically. The G-PAM
polymer(s) can be added in liquid form and can be added separate from the
microparticles. The
microparticles can be added as a suspension. The microparticles or suspension
thereof can be
added separately. Any references to a retention/drainage additive system
herein with regard to
these two components refer to their joint presence after addition in any
manner or sequence to the
fiber suspension to be treated. Both components can be introduced to the fiber
suspension before
sheet formation. This can be carried out, for example, by adding the
glyoxalated polyacrylamide
polymers in the form of an aqueous composition, and the silicon-containing
microparticles in dry
powder form or as an aqueous dispersion (same or different as the G-PAM
polymer
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
composition), to the fiber suspension in a mixing tank or some other point in
the papermaking
machine in which there is suitable agitation, such that the two components are
dispersed with the
components forming the paper and thus can act simultaneously with each other
and/or with the
components for forming the paper. Pulp collected on a forming wire screen can
be further
drained, pressed, and dried, and optionally further can be coated and
converted. Any pulp fibers
drained through the wire can be optionally recirculated to a white water silo.
[00301 Before de-watering, the fiber suspension treated with the combination
of glyoxalated
polyacrylamide polymers and silicon-containing microparticles can have one or
more optional
additional additives mixed into the fiber suspension, such as one or more
process additives
and/or functional additives, including those conventionally used in
papermaking. For example,
optional additives can be introduced, for example, in a conventional blend
chest or other
convenient location within a papermaking system before or after sheet
formation. These optional
additives can include, e.g., additional polymers such as cationic, anionic
and/or non-ionic
polymers, clays, other fillers, dyes, pigments, defoamers, pH adjusting agents
such as alum,
sodium aluminate, and/or inorganic acids, such as sulfuric acid, microbicides,
cationic colloidal
alumina microparticles, coagulants, flocculants, and/or other conventional and
non-conventional
papermaking or processing additives. These optional additives, if used, are
used in an amount
effective for their respective purpose. In this respect, it is important to
ensure that the content of
these other optional agents do not adversely effect or impede the beneficial
drainage and
retention effects imparted by the glyoxalated polyacrylamide polymers and
silicon-containing
microparticles. The additive system comprising the glyoxalated polyacrylamide
polymer
composition and silicon-containing microparticles can be added to fiber
suspension over a wide
range of pH values. However, best results should be obtained by adding the
composition to the
11
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
fiber suspension at a pH of from about 4 to about 8, most preferably from 5.5
to 7Ø The G-PAM
compositions and silicon-containing microparticles described herein are
readily absorbed or
retained by the cellulose fibers at these pH values.
[0031] As indicated, silicon-containing microparticles are one of the
components of the
improved retention/drainage additive system of the present invention. The
silicon-containing
microparticles are, for example, solid microparticles containing silicon (Si).
The solid
microparticles containing silicon can be, for example, inorganic crystalline
or non-crystalline
materials. The silicon content of the microparticles can be, for example,
chemically bonded (e.g.,
covalent, ionic, metallic), complexed, hydrogen bonded, van der Waals force
bonded, and/or
physically entrapped, or combinations thereof. The microparticles can be added
to the fiber
suspensions being treated as dry powders or as dispersions in water or other
suitable liquid
carriers. Use of microparticle dispersions can assist in distribution of the
solid microparticles in
the fiber suspensions and/or can avoid possible practical concerns associated
with handling and
use of dry powders.
[0032] The silicon-containing microparticle can comprise silica
microparticles. The silica
microparticles can be used in dry powder form (including dry to the touch
gels) or in dispersed
form. The silica microparticles can comprise, for example, amorphous silica
microparticles or
crystalline silica microparticles. The silica microparticles can be, for
example, in the form of
colloidal silica, colloidal silicic acid, silica sols, fumed silica,
agglomerated silicic acid, silica
gels, and precipitated silicas, or any combinations thereof. For instance,
silica (e.g., amorphous
silica nanoparticles and bentonite can be added separately or as a mixture
(e.g., as a suspension).
The silica microparticles can be, for example, inorganic silicates, such as
aluminum silicates
(e.g., kaolin clay). The silica microparticles can be dispersed amorphous
silica microparticles.
12
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
For purposes herein, the terminology "silica microparticles" means finely
divided silica having a
particle size according to the present invention, and the term encompasses
silica primary
particles, silica aggregates (i.e., unitary clusters of a plurality of silica
primary particles), silica
agglomerates (i.e., unitary clusters of a plurality of silica aggregates),
individually or in
combinations thereof.
[0033] The silicon-containing microparticles can comprise, for example,
colloidal silica
comprising a surface area from 300 m2/g to 1000 m2/g, 500 m2/g to 800 m2/g, or
600 m2/g to 750
m2/g, and an S-value from 80% to 20%, 70% to 30%, or 60% to 40%. For purposes
herein, the
"surface area" and "S-value" of the silica particles can be determined by
respective methods such as
described in U.S. Pat. No. 5,603,805, which is incorporated in its entirety by
reference herein. The
colloidal silica can be aluminate-treated or untreated. The silica
microparticles have a dry particle
size, for example, of not greater than about 1,000 rim, 1 nm to 750 nm, 2 nm
to 500 nm, 3 nm to
500 nm, 4 nm to 100 nm, 5 nm to 50 rim, or 10 nm to 30 nm, on an average or
absolute particle
size basis. The silica microparticles can have an absolute particle size
within one or more of
these size ranges. The dry particle size distribution of the silica particles
is, for example, such
that at least 90%, or at least 95%, or at least 99% up to 100%, have an
absolute particle size of
less than 1000 nm, or less than 750 nm, or less than 500 nm, or less than 100
run, or less than 75
nm, or less than 50 nm. The presence of larger sized silicon-containing
particles in the wet-end of
papermaking is not excluded; however, they are not needed for purposes of
obtaining the
improved retention and drainage according to the present invention.
[0034] Colloidal silica solutions are frequently commercially supplied as 5%
up to 50% by
weight dispersions, which typically are diluted for use in processes according
to the present
invention, although not necessarily. A preferred commercial dispersion of
silica is available from
13
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
Eka Chemicals, Inc. (Marietta, GA), such as EKA NP series, e.g., Eka NP 890, a
high-solids,
surface-modified, structured, anionic silica sol for all pH ranges. As
indicated, the silica
dispersions may be used as received or as diluted for use according to the
present invention. The
concentration of silica microparticles when used in an aqueous silica
suspension, colloid, sol, or
other dispersion, can be, for example, between about 0.1 % and about 20% by
weight, or about 5
to about 15% by weight, or other ranges. The viscosity of the aqueous silica
suspension can be
less than 50 mPa=s (measured using a Brookfield viscometer at 100 rpm).
[00351 The paper made in processes according to the present invention can
comprise from
about 0.05 to about 2.5 pounds (lb.) silica microparticles/ton dry fiber,
about 0.1 to about 1 lb.
silica microparticles/ton dry fiber, or about 0.2 to about 0.8 lb. silica
microparticles/ton dry fiber
(on a solids/solids basis). The amount of silica microparticles added, on a
solids basis, can be
expressed in weight percentage terms, wherein the amount of added silica
microparticles can be
as low as about 0.0025 wt% of the dry weight of the cellulose fibers, but
usually does not exceed
about 0.125% by weight. An amount of silica microparticles in the range of
about 0.005 wt% to
0.1 wt% of the dry paper weight is more usual.
[00361 As indicated, the silicon-containing microparticle can be bentonite
microparticles.
The bentonite microparticles can be used in dry powder form or in dispersed
form. Bentonite
generally comprises an absorbent aluminum phyllosilicate, generally impure
clay consisting
mostly of montmorillonite. Types of bentonites can include different dominant
metals, such as
potassium, sodium, calcium, and aluminum, or other metal. As regards the
bentonite dispersion,
this preferably can be a bentonite suspension consisting of any type of
commercial product
referred to as bentonite or as bentonite-type clay, i.e. anionic swelling
clays such as sepialite,
attapulgiteor, preferably, montmorillonite. The clays may or may not be
chemically modified, for
14
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
example, by alkaline treatment to exchange the calcium of bentonite for an
alkali metal or alkali
(e.g., sodium, potassium, or ammonium). The montmorillonite clays that can be
suitable include,
for example, Wyoming bentonites and soapy earths. The swelling clays are
usually metal
silicates comprising a metal chosen from aluminum and magnesium, and
optionally other metals,
and the ratio of silicon atoms to metal atoms at the surface of the clay
particles, and generally
within their structure, is from 5/1 to 1/1. For most montmorillonites, the
ratio is relatively low,
the metal being essentially or totally aluminum, but with a small amount of
magnesium and
occasionally with, for example, a small amount of iron. However, in other
swelling clays, all or
some of the aluminum is replaced with magnesium and the ratio may be very low,
for example
about 1.5 for sepialite. The use of silicates in which some of the aluminum
has been replaced
with iron also can be used.
[00371 The bentonite microparticles can have a dry particle size, for example,
of not greater
than about 1,000 nm, 1 nm to 750 nm, 2 nm to 500 nm, 3 nm to 500 nm, 4 nm to
100 nm, 5 nm
to 50 nm, or 10 nm to 30 nm, on an average or absolute particle size basis.
The bentonite
microparticles can have an absolute particle size within one or more of these
size ranges. The dry
particle size distribution of the bentonite particles is, for example, such
that at least 90%, or at
least 95%, or at least 99% up to 100% (% based on the total weight of
microparticles), have an
absolute particle size of less than 1000 nm, or less than 750 nm, or less than
500 nm, or less than
100 nm, or less than 75 nm, or less than 50 nm. The surface area of the
bentonite before swelling
can be at least 30 m2/g, at least 50 m2/g, or from 60 to 90 m2/g, and the
surface area after swelling
can be from 400 to 800 m2/g. The bentonite preferably swells, for example, by
a factor of at least 15
to 20-fold. The size of at least 90% (by weight) of the particles after
swelling is preferably less than
2 microns, or 1 micron, or other values. Bentonite microparticles having these
properties can be
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
produced by known methods or commercially obtained, such as by using or
readily adapting
methods described in U.S. Pat. Nos. 4,305,781, 4,753,710, and 6,270,626, which
are incorporated
in their entireties by reference herein. If necessary, dried bentonite ores
can be pulverized by means
of an attrition grinding machine, such as a centrifugal roller mill, or an
impact mill, such as a
hammer mill, sufficient to provide microparticle sizing and/or any desired
particle distribution of
microparticles.
[0038] The concentration of bentonite when used in an aqueous bentonite
suspension, can be,
for example, between about 0.1% and 10% by weight, or about 0.2 to about 5% by
weight, or
other ranges. The viscosity of an aqueous bentonite suspension is generally
less than 500 mPa=s
(measured using a Brookfield viscometer at 100 rpm).
[0039] The paper made in processes according to the present invention can
comprise from
about 0.05 to about 2.5 pounds (lb.) bentonite microparticles/ton dry fiber,
about 0.1 to about 1
lb. bentonite microparticles/ton dry fiber, or about 0.2 to about 0.8 lb.
bentonite
microparticles/ton dry fiber (on a solids/solids basis). The amount of
bentonite microparticles
added, on a solids basis, can be expressed in weight percentage terms, wherein
the amount of
added bentonite microparticles can be as low as about 0.0025 wt% of the dry
weight of the
cellulose fibers, but usually does not exceed about 0.125% by weight. An
amount of bentonite
microparticles in the range of about 0.005 wt% to 0.1 wt% of the dry paper
weight is more usual.
[0040] The silicon-containing microparticles can be added to paper pulp in
combination with a
glyoxalated polyacrylamide containing at least about 25% by weight cationic
monomer in the wet-
end of a papermaking process to improve retention and/or drainage. The paper
made in processes
according to the present invention can comprise from about 0.5 to about 12
pounds (lb.)
polymer/ton dry fiber, about 1 pound to about 8 lb. polymer/ton dry fiber, or
about 2 to about 6
16
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
lb. polymer/ton dry fiber (on a solids/solids basis). The amount of
glyoxalated polyacrylamide
polymer added, on a solids basis, can be expressed in weight percentage terms,
wherein the
amount of added glyoxalated polyacrylamide polymer can be as low as about 0.03
wt% of the dry
weight of the cellulose fibers, but usually does not exceed about 10% by
weight. An amount of
polymer in the range of about 0.1 wt% to 5 wt% of the dry paper weight is more
usual.
[0041] The glyoxalated polyacrylamide polymers containing at least about 25%
by weight
cationic monomer can be introduced into the suspension undergoing treatment in
high solids
aqueous compositions thereof that are storage-stable at high polymer
concentrations. The
glyoxalated polyacrylamide compositions according to the present invention can
have a solids
concentration, for example, from about 1% and about 30%, by weight, or, for
example, from
about 5% to about 30%, by weight, or, for example, about 7% to about 15%, by
weight or, for
example, about 7% to about 13%, by weight.
[0042] The glyoxalated acrylamide polymer according to the present invention
can comprise,
for example, from about 75% to about 10%, by weight, acrylamide monomer and
from about
25% to about 90%, by weight, cationic monomer copolymerizable with the
acrylamide monomer,
and has sufficient glyoxal-reactive amide substituents and -CHOHCHO
substituents to be
thermosetting. The glyoxalated acrylamide polymer can comprise, for example,
from about 70%
to about 30%, by weight, acrylamide monomer and from about 30% to about 70%,
by weight,
cationic monomer, or, for example, from about 65% to about 50%, by weight,
acrylamide
monomer and from about 35% to about 50%, by weight, cationic monomer, or, for
example,
from about 62% to about 55%, by weight, acrylamide monomer and from about 38%
to about
45%, by weight, cationic monomer.
[0043] A glyoxalated polyacrylamide polymer according to the present invention
can
17
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
incorporate a base polymer resin having the following exemplary formula
X A Jy L B" Jz
0
NH2
wherein R is H, C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, or halogen; A is a
cationic unit which
imparts a charge to the resin polymer; B is an optional non-nucleophilic unit
which does not react
with glyoxal under aqueous condition; wherein the weight percent of x is from
75% to about
10%; the weight percent of y is from 25% to about 90%,; the weight percent of
z is from 0% to
65%; and the molecular weight of the base polymer resin is from 500 Daltons to
100,000
Daltons, or, for example, 3,000 Daltons to 20,000 Daltons, or, for example,
3,000 Daltons to
13,000 Daltons, or, for example, 5,000 Daltons to 9,000 Daltons.
[0044] These base polymer resins are glyoxalated to provide thermosetting
resins that are
particularly suitable for use as co-additives with silicon-containing
microparticles for
papermaking, increasing papermaking fiber retention and de-watering rate,
and/or providing
paper with good dry and temporary wet strength. The glyoxalation of
polyacrylamide according
to an exemplary illustration is schematically indicated below.
R R R
: w x Y
W x
CHOCHO O O
O
NH N+ NH2 NH N
2
hOH
0
[0045] Glyoxal reacts with amide groups to form a pendant glyoxalated group.
In addition,
glyoxal cross-links the base polymer molecules at glyoxal-reactive amide
substituents of the
18
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
acrylamide units (not shown), leading to a thermosetting interpolymer and an
associated increase
of solution viscosity. The presence of high cationic monomer content in the
resulting glyoxalated
polyacrylamide polymers according to the present invention reduces the amide
content and/or the
cross-linking rate. Thus, the product can be prepared at a higher solid
content but with longer shelf
life. This higher charged glyoxalated polyacrylamide resin also gives
comparable wet/dry strength
in paper as commercially available 7.5% glyoxalated polyacrylamide products.
As indicated, higher
de-watering rates during the papermaking process are obtained by treating
pulps with silicon-
containing microparticles and the glyoxalated polyacrylamide polymer products
of the present
invention as compared to commercially available lower solids glyoxalated
polyacrylamide polymer
products.
[00461 Cationic monomers include, for example, 2-vinylpyridine, 2-vinyl-N-
methylpyridinium chloride, (p-vinylphenyl)trimethyl ammonium chloride,
diallyldimethylammonium chloride, 2-(dimethylamino)ethyl acrylate, trimethyl(p-
vinylbenzyl)ammonium chloride, p-dimethylaminoethylstyrene,
dimethylaminopropyl
acrylamide, 2-methylacroyloxyethyltrimethyl ammonium methylsulfate, and 3-
acrylamido-3-
methylbutyl trimethyl ammonium chloride.
[00471 The acrylamide can be replaced by other primary amide-containing
monomers such as
methacrylamide, ethylacrylamide, crotonamide, N-methyl acrylamide, N-butyl
acrylamide, N-
ethyl methacrylamide and the like. Thus, polyacrylamides, which by definition
are polymers
made from acrylamide monomers, include repeating units from at least one or
more of these
various compounds.
[00481 The acrylamide monomer provides the primary reaction sites on the base
polymer
backbone to which the glyoxal substituents are attached. The base polymer must
have a sufficient
19
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
number of base acrylamide monomers in its structure (pendant amide groups) so
that, once
functionalized with glyoxal, the resulting polymer is thermosetting. As used
herein,
"thermosetting" and "crosslinking", and similar terms are intended to embrace
the structural
and/or morphological change that occurs, for example, by covalent chemical
reaction or ionic
interaction between separate molecules in a composition. Generally, the amount
of base
acrylamide monomer should be at least about 10 weight percent of the base
polymer. Paper
strengthening properties of the resulting polymer generally will increase with
increased amounts
of acrylamide content, although it has been found in the present invention
that adequate dry
strength properties can be provided in higher cationic monomer content
polyacrylamide base
polymers according to the present invention. The base acrylamide monomer is
normally provided
in an amount of at least about 50 weight percent and sometimes in excess of 60
weight percent of
the total vinyl monomers from which the base polyacrylamide is prepared.
[00491 The base polymer optionally can also contain a non-nucleophilic monomer
to reduce
amide-glyoxal cross-linking reaction. The suitable non-nucleophilic monomers
include vinyl
acetate, N-vinylpyrrolidone, N,N-dimethylacrylamide, acrylonitrile, styrene,
hydroxyl
alkyl(meth)acrylates and the like. The weight percent of this non-nucleophilic
unit can range
from zero to 65 (e.g., 1 wt% to 80 wt%, 5 wt% to 70 wt%, 10 wt% to 60 wt%, 15
wt% to 50
wt%o, 20 wt% to 40 wt% and so on).
[00501 The base polymer product of the copolymerization of the acrylamide
monomer and
cationic monomer for use in the present invention, or polyacrylamide base
polymer, can be
prepared by free radical polymerization in an aqueous system. Methods for
making base
polyacrylamide can be modified to practice the present invention. To prepare a
polyacrylamide
base polymer of a desired chemical composition and monomer distribution, the
full complement
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
of the cationic monomer(s) and the non-nucleophilic monomer(s) can be added
all at once at the
beginning of the polyacrylamide polymerization reaction. Alternatively, the
cationic monomer(s)
and the non-nucleophilic monomer(s) can be added continuously along with
acrylamide
monomer over the time course of the polymerization reaction. Still other
options for reacting the
cationic monomers and the non-nucleophilic monomers with the acrylamide
monomer will be
recognized by those skilled in the art, such as sequentially, batch, semi-
batch, and the like.
Commonly used free radical initiators that can be used in the present
invention include various
peroxide, azo compounds, potassium and ammonium persulfates, and a redox
initiator system.
The polyacrylamide base polymer has a molecular weight ranging, for example,
from 500
Daltons to 100,000 Daltons, for example, from 3,000 Daltons to 20,000 Daltons,
for example,
from 3,000 Daltons to 13,000 Daltons, for example, from 5,000 Daltons to 9,000
Daltons. The
molecular weight can be influenced by changing the reaction temperature, the
level of solids in
the reaction, the amount of initiator, the amount of chain transfer agent, and
by other methods
used by those skilled in the art. The suitable chain transfer agents include
isopropyl alcohol,
mercaptans, sodium formate, and sodium acetate.
[00511 The so-prepared base polymer can then be reacted with glyoxal, for
instance, at a pH
of 7 to 10. The weight ratio of the glyoxal to the base polymer ranges, for
example, from about
0.01 to about 0.60:1, and for example, from about 0.10 to about 0.30:1,
respectively. The
reaction temperature can be maintained in the range of 15 C to 50 C. A buffer
can be added to
control solution pH throughout the reaction. Suitable buffers include sodium
phosphates, sodium
pyrophosphate, borax, and Tris. Once the solution reaches a desired viscosity,
dilute acid can be
added to quench the reaction. The final pH of the solution can range from 2 to
5. Alternatively,
either the glyoxal solution or the base polymer solution can be added to the
reaction mixture
21
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
slowly over time, or both the glyoxal and the base polymer solution can be
added to the reaction
mixture slowly over time. Still other options for reacting glyoxal and base
polymer can be used
by those skilled in the art.
[00521 The compositions of the higher charged glyoxalated polyacrylamide
polymers
according to the present invention can be readily employed or stored for later
use in the
manufacture of paper as an aqueous solution. The compositions are highly
storage stable, even at
temperatures exceeding room temperature. As previously indicated, it is not
necessary to add
stabilizers or other storage-life promoting additives to the high solids
polymer compositions
according to the present invention to achieve significantly improved shelf
life over conventional
7.5% glyoxalated polyacrylamide polymer formulations. The glyoxalated
polyacrylamide
polymer compositions according to the present invention do not need extraneous
stabilizers,
aldhehyde scavengers, and/or surfactants, and the like, to achieve the
improvements in storage
stability, although these materials are not categorically excluded. The
glyoxalated polyacrylamide
polymer compositions of the present invention can contain no such stabilizer
additives or can be
essentially free of them (that is, contain < 0.1 wt% total stabilizers,
aldehyde scavengers, and
surfactants).
[00531 The high solids glyoxalated acrylamide polymer compositions of the
present
invention can have a viscosity of less than about 45 cps (e.g., 1 cps to 24
cps, or 5 cps to 20 cps,
or 10 cps to 20 cps), or particularly less than 25 cps, as measured on a
Brookfield viscometer
using #2 spindle at 60 rpm after 14 days storage at 37 C. The high solids
glyoxalated acrylamide
polymer composition can have a viscosity of less than about 25 cps, as
measured on a Brookfield
viscometer using #2 spindle at 60 rpm (e.g., 1 cps to 24 cps or 5 cps to 20
cps, or 10 cps to 20
cps) after 28 days storage at 37 C. These properties indicate very little if
any gelling occurs in the
22
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
polymer compositions according to the present invention within at least these
storage periods and
conditions.
[0054] The base polymer can have a charge density of 1.0 meg/g or greater,
such as from
about 1.0 to about 4.5 meq/g, such as from 1.1 to 4.5 meg/g or from 1.5 to 3.5
meg/g and the
like. Improved and unexpected properties have been achieved especially in the
range of from 1 to
4.5 meg/g.
[0055] The additive system combining glyoxalated polyacrylamide polymer and
silicon-
containing microparticles according to the present invention is not limited to
treating any
particular type of paper and should find application in all grades of paper,
Kraft paper, sulfite
paper, semichemical paper, and the like, including paper produced using
bleached pulp,
unbleached pulp, or combinations thereof. For example, the drainage and
retention improvements
due to the combination of the glyoxalated polyacrylamide polymers and silicon-
containing
microparticles according to the present invention can be observed in different
types of pulps. For
example, the pulp may comprise virgin and/or recycled pulp, such as virgin
sulfite pulp, broke
pulp, a hardwood kraft pulp, a softwood kraft pulp, old corrugated containers
(OCC), mixtures of
such pulps, and the like. There are a variety of mechanical pulping methods to
which the present
invention can be applied. For example, thermomechanical pulp (TMP) uses a
combination of
heated wood chips and mechanical processes. Stone Groundwood (SOW) grinds or
macerates the
wood chips. Chemithermomechanical pulp (CTMP) uses a variety of chemicals,
heat, and
grinding techniques to produce pulp. Different types of pulp require different
types of paper
although many papers can use a combination or "blend" of several different
types of pulp and
recycled/recovered paper. These pulp formulations can be referred to as fiber
furnishes.
[0056] A paper product can be provided comprising the glyoxalated
polyacrylamide polymer
23
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
and silicon-containing microparticles of the present invention. The product
may comprise at least
one paper layer or web containing the glyoxalated polyacrylamide polymer and
silicon-
containing microparticles, for example, paper sheeting, liner board,
newsprint, paperboard, tissue
paper, fluting medium, and wall board.
[0057] The present invention will be further clarified by the following
examples, which are
intended to be purely exemplary of the present invention, in which all
percentages, parts, ratios
and the like are proportions by weight unless otherwise specified.
EXAMPLES
[0058] In these experiments, the effects of a combination of high solids,
higher charged
glyoxalated polyacrylamide polymer and silicon-containing microparticles
representing various
non-limiting embodiments of the present invention on the de-watering rate and
retention
properties of an aqueous cellulosic suspension were compared to that of
several commercial
polyacrylamide and polyamine based additives in their as-supplied product
forms and modified
forms thereof.
[0059] Molecular weights of the base polymers of the polyacrylamide polymers
were
determined in the following manner. Polymer molecular weight was characterized
using Waters
Breeze System - Gel Permeation Chromatography (GPC). The elution solvent was
an aqueous
buffer solution containing 0.8 mole/L sodium nitrate and 0.1 mole/L acetic
acid. In a typical
GPC experiment, concentrated polymer sample was diluted with the elution
solvent to give a
final concentration of around 0.1%. The diluted polymer solution was injected
into the system
using a Waters 717plus Autosampler and pumped through a Waters Ultrahydrogel
Guard
Column followed by a Waters Ultrahydrogel Linear Column. The flow rate was
0.9 ml/min.
24
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
The molecular weight distribution of the polymer sample was calculated based
on a calibration
curve determined using poly(ethylene glycol) standard GPC calibration kit from
Polysciences.
Example 1
Synthesis of Polyacrylamide Base Polymers
[0060] Into a reaction vessel equipped with reflux condenser, stirrer, and
thermometer were
added water, sodium formate, and a DADMAC aqueous solution (64 wt%). This
portion of
DADMAC added in the beginning of the reaction is referred to herein as "DADMAC
1". The
vessel was then heated to 80 C and maintained at this temperature. To the
vessel were slowly
added acrylamide aqueous solution (50%), DADMAC aqueous solution (64%), and
ammonium
persulfate. The addition time of acrylamide and diallyldimethylammonium
chloride was 190
minutes and the addition time of ammonium persulfate was 220 minutes. The
portion of
DADMAC added over this 190 minute addition period is referred to herein as
"DADMAC 2".
The reaction mixture was then heated at 80 C for an additional one hour and
was then cooled to
room temperature. Table 1 listed the addition dosages of all the compounds
used in synthesizing
the base polymers.
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
Table 1. Base polymer preparation dosages.
Water Sodium DADMA Acryl- DADM Ammonium Total Charge Weight
(g) formate C I (g) amide AC 2 persulfate DADMA density average
(g) (g) (g) (g) C (meq/g) molecular
weight (Da)
(wt%)
Base 58.3 5.1 6 165 53 12.3 (14% in 32 2.0 8000
polymer 1 water)
Base 74 4.4 16 155 65 6.5 (23% in 40 2.5 8900
polymer 2 water)
Base 84.7 4.3 16 116 95 7.15 (23% in 55 3.1 7600
polymer 3 water)
Base NA NA NA NA NA NA 9.5 0.6 NA
polymer
for
Bubond
376
Glyoxalation
100611 The glyoxalation of the base polymers was conducted in the following
manner. Into a
reaction vessel were added water, base polymer, and sodium pyrophosphate.
After 15 minutes of
mixing, the pH of the reaction mixture was increased to 8.8 using 15% NaOH
solution and the
temperature of the mixture was maintained at 25 C. Once the viscosity of the
mixture reached 15
cp, solution pH was lowered to 3.0 immediately using 25% H2SO4. The products
were stored at
4 C until further testing. Table 2 lists the dosages of all the compounds for
glyoxalation. The
products of these reactions were aqueous compositions containing the G-PAM
polymers as
active content therein. The numbering of the G-PAM products in Table 2
corresponds to the
26
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
numbering of the Base polymers (see Table 1) used to synthesize the G-PAM
product.
Table 2. Glyoxalation dosages.
Product Water Base polymer (g) Glyoxal Sodium Final
(g) (40%) Pyrophosphate active
(g) (g) content
(wt%)
G-PAM 1 143 47 12 1.2 11.6%
(Base pol merl)
G-PAM2 13 8 47 13 1.2 12.0%
(Base polymer2)
G-PAM3 128 57 15 1.5 14.3%
(Base polymer3)
OCC suspension de-watering test
[0062] In this test, the effect of different G-PAMs, with and without silicon-
containing
microparticles, on OCC (old corrugated cardboard) suspension de-watering rate
and retention
was studied. Pulp stock was post-refining recycled old corrugated cardboard
(OCC) obtained
from National Gypsum Company Pryor Papermaking Mill. For comparison, high
solid G-PAM
samples combined with silicon-containing microparticles were tested against
commercial
products BUBOND 376 (Buckman International) and BUFLOC 5031 (Buckman
International). BUBOND 376 is a conventional G-PAM product with 7% active
content and its
basepolymer has 9.5 wt% DADMAC. BUFLOC 5031 is a polyamine product which has
been
widely applied as a coagulant to improve paper retention drainage.
[0063] In a typical test, 800 mL 1.0% OCC suspension was added to a Mutek DFR-
4
drainage/retention tester and was then mixed at 900 rpm. G-PAM or polyamine
was added five
seconds before the addition of commercial cationic polyacrylamide flocculant
BUFLOC 5511.
Five seconds after the addition of BUFLOC 5511, mixing rate was lowered to
650 rpm. If
27
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
applicable, a silicon-containing microparticulate retention aid, silica NP 890
(EKA), was added
immediately after the mixing rate was lowered to 650 rpm. In Table 3, dosages
of components
are described in terms of pounds (lb) component/ton dry fiber. After another
five seconds, the
mixing was stopped and 400 mL filtrate was allowed to pass through a 60 mesh
wire. A higher
drainage rate indicates a faster production rate, which can translate into a
lower energy
consumption during the paper drying process. Filtrate turbidity was recorded
using a HACH
2100 turbidimeter. A lower turbidity indicates a higher retention efficiency.
Table 3. Retention and drainage test results.
Sample Additives and Dosages Filtrate turbidity 400 mL
(ntu) drainage time
(s)
1 0.5 lb/ton BUFLOC 5511 512 42
2 5 lb/ton BUFLOC 5031 + 0.5 lb/ton BUFLOC 346 39.8
5511
3 5 lb/ton BUBOND 376 + 0.5 lb/ton BUFLOC 498 41.5
5511
4 5 lb/ton G-PAM1 + 0.5 lb/ton BUFLOC 5511 306 37.7
5 lb/ton G-PAM2 + 0.5 lb/ton BUFLOC 5511 320 37.9
6 5 lb/ton G-PAM3 + 0.5 lb/ton BUFLOC 5511 330 39
7 5 lb/ton BUFLOC 5031 + 0.5 lb/ton BUFLOC 318 28.5
5511 + 0.5 lb/ton silica
8 5 lb/ton BUBOND 376 + 0.5 lb/ton BUFLOC 481 38
5511 + 0.5 lb/ton silica
9 5 lb/ton G-PAM1 + 0.5 lb/ton BUFLOC 5511 + 0.5 295 29
lb/ton silica
5 lb/ton G-PAM2 + 0.5 lb/ton BUFLOC 5511 + 0.5 297 30
lb/ton silica
11 5 lb/ton G-PAM3 + 0.5 lb/ton BUFLOC 5511 + 0.5 304 28.3
lb/ton silica
12 5 lb/ton BUFLOC 5031 + 0.5 lb/ton BUFLOC 340 24.6
5511 + 0.75 lb/ton silica
13 5 lb/ton G-PAM1 + 0.5 lb/ton BUFLOC 5511 + 0.75 259 24.9
lb/ton silica
14 5 lb/ton G-PAM2 + 0.5 lb/ton BUFLOC 5511 + 0.75 274 24.3
lb/ton silica
5 lb/ton G-PAM3 + 0.5 lb/ton BUFLOC 5511 + 0.75 301 23.4
lb/ton silica
28
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
[00641 As shown in Table 3, the addition of silica microparticles increased
retention/drainage
performance significantly of all three high solids G-PAM products. Further,
all three high solids
G-PAM products, when used in combination with silica microparticles, provided
much lower
filtrate turbidities and faster drainage rate than the conventional commercial
G-PAM product
BUBOND 376, with or without the silica. Furthermore, all three high solids G-
PAM products,
when used in combination with silica microparticles, also provided lower
filtrate turbidities and
comparable drainage rate than the commercial coagulant BUFLOC 5031, with or
without the
silica. In view of these showings, it is further believed that high solids G-
PAM products, when
used in combination with silica microparticles, can be applied to replace both
conventional G-
PAM products as dry strength resin and also conventional polyamine products as
coagulant.
[00651 Applicants specifically incorporate the entire contents of all cited
references in this
disclosure. Further, when an amount, concentration, or other value or
parameter is given as either a
range, preferred range, or a list of upper preferable values and lower
preferable values, this is to be
understood as specifically disclosing all ranges formed from any pair of any
upper range limit or
preferred value and any lower range limit or preferred value, regardless of
whether ranges are
separately disclosed. Where a range of numerical values is recited herein,
unless otherwise stated,
the range is intended to include the endpoints thereof, and all integers and
fractions within the
range. It is not intended that the scope of the invention be limited to the
specific values recited
when defining a range.
[00661 Other embodiments of the present invention will be apparent to those
skilled in the art
from consideration of the present specification and practice of the present
invention disclosed
herein. It is intended that the present specification and examples be
considered as exemplary
29
CA 02766790 2011-12-23
WO 2011/002677 PCT/US2010/039951
only with a true scope and spirit of the invention being indicated by the
following claims and
equivalents thereof.
