Title of Invention

A METHOD OF ENHANCING THE DEWATERING OF A PAPER SHEET ON A PAPER MACHINE

Abstract A method of enhancing the dewatering of a paper sheet on a paper machine comprising adding to the paper sheet 0.05 lb/ton to 15 lb/ton, based on dry fiber, of one or more aldehyde functionalized polymers comprising amino or amido groups wherein at least 15 mole percent of the amino or amido groups are functionalized by reacting with one or more aldehydes and wherein the aldehyde functionalized polymers have a weight average molecular weight of at least 100, 000 g/mole.
Full Text

METHOD OF USING ALDEHYDE-FUNCTIONALIZED POLYMERS TO
ENHANCE PAPER MACHINE DEWATERING
TECHNICAL FIELD
This is a method of enhancing paper machine dewatering using aldehyde-
functionalized polymers having a specific level of functionalization.
BACKGROUND OF THE INVENTION
Papermaking comprises taking a slurry of papermaking raw materials at a
consistency (weight percent solids) in the range 0.1 to 1.0 weight percent and
dewatering it to form a sheet with a final consistency of about 95 weight percent.
Paper machines accomplish this dewatering through a series of different processes
which include from the beginning to end: 1) gravity or inertial dewatering (early
forming section of the machine); 2) vacuum dewatering (late forming section of the
machine); 3) press dewatering (press section of the machine); and 4) thermally
evaporating the water (dryer section of the machine). The cost of dewatering increases
in going from 1 to 4, which makes it advantageous to remove as much water as
possible in the earlier stages. The rate of paper production or, equivalently, the
machine speed is dictated by the rate at which the water can be removed, and
consequently, any chemical treatment which can increase the rate of water removal has
value for the papermaker. Many grades of paper require the use of retention aid
chemicals for their manufacture in order to retain the fine particles found in the raw
materials used to make the paper. It is well known in the paper industry that these
retention aids can also enhance the rate of gravity, inertial, and vacuum dewatering or
drainage, as it is often called. Such retention chemicals include the well known
flocculants, coagulants, and microparticles used in the industry. Existing laboratory
free and vacuum drainage tests can readily identify the drainage effects of these
retention aid chemicals.
The production rate for the vast majority of paper machines is limited by the
drying capacity of the machine's dryer section. Consequently, the consistency of the
paper sheet leaving the press section and going into the dryer section is most often

critical in determining the paper machine speed or production rate. The effects of
chemical additives on press dewatering are unclear with little information available on
this topic. The effect of retention aid chemicals on press dewatering is often reported
to be detrimental as a consequence of the decreased consistency entering the press as a
result of increased water retention or reduction in press efficiency resulting from a loss
in sheet formation. Both these factors arise from the flocculation of the papermaking
particles by the retention chemicals. Because the consistency of the sheet leaving the
press section is most often the most critical factor in determining machine speed, any
treatment capable of increasing this consistency would obviously be highly desirable.
Currently, no chemical treatments are known to be marketed as commercial press
dewatering aids, although anecdotal reports suggest that some polymers can favorably
effect out going press consistency. Accordingly, there is an ongoing need to develop
compositions having effective press dewatering activity.
Glyoxylated polyvinylamides prepared from glyoxal and polyvinylamide in a
mole ratio of 0.1 to 0.2 are disclosed as wet strength resins in U.S. Pat. No. 3,556,932.
Low molecular weight glyoxylated cationic polyacrylamides prepared from
glyoxal and cationic polyvinylamide in a ratio of 0.1-0.5:1 are disclosed as temporary
wet strength resins in U.S. Patent No. 4,605,702.
A method of imparting strength to paper by adding to a pulp slurry a mixed
resin comprising an aminopolyamide-epichlorohydrin resin and a glyoxylated
acrylamide-dimethyl diallyl ammonium chloride resin prepared from glyoxal and
acrylamide-dimethyl diallyl ammonium chloride copolymer in a molar ratio of about 2-
0.5:1 is disclosed in U.S. Patent No. 5,674,362.
SUMMARY OF THE INVENTION
This invention is a method of enhancing the dewatering of a paper sheet on a
paper machine comprising adding to the paper sheet about 0.05 lb/ton to about 15
lb/ton, based on dry fiber, of one or more aldehyde functionalized polymers comprising
amino or amido groups wherein at least about 15 mole percent of the amino or amide
groups are functionalized by reacting with one or more aldehydes and wherein the

aldehyde functionalized polymers have a weight average molecular weight of at least
about 100,000 g/mole.
DETAILED DESCRIPTION OF THE INVENTION
"Acrylamide monomer" means a monomer of formula

wherein R1 is H or C1-C4 alkyl and R2 is H, C1-C4 alkyl, aryl or arylalkyl. Preferred
acrylamide monomers are acrylamide and methacrylamide. Acrylamide is more
preferred.
"Aldehyde" means a compound containing one or more aldehyde (-CHO)
groups, where the aldehyde groups are capable of reacting with the amino or amido
groups of a polymer comprising amino or amido groups as described herein.
Representative aldehydes include formaldehyde, paraformaldehyde, glutaraldehyde,
glyoxal, and the like. Glyoxal is preferred.
"Alkyl" means a monovalent group derived from a straight or branched chain
saturated hydrocarbon by the removal of a single hydrogen atom. Representative alkyl
groups include methyl, ethyl, n- and iso-propyl, cetyl, and the like.
"Alkylene" means a divalent group derived from a straight or branched chain
saturated hydrocarbon by the removal of two hydrogen atoms. Representative alkylene
groups include methylene, ethylene, propylene, and the like.
"Amido group" means a group of formula-C(O)NHY1 where Y1 is selected
from H, alkyl, aryl and arylalkyl.
"Amino group" means a group of formula -NHY2 where Y2 is selected from H,
alkyl, aryl and arylalkyl.
"Amphoteric" means a polymer derived from both cationic monomers and
anionic monomers, and, possibly, other non-ionic monomer(s). Representative
amphoteric polymers include copolymers composed of acrylic acid and

DMAEA-MCQ, terpolymers composed of acrylic acid, DADMAC and acrylamide, and
the like.
"Aryl" means an aromatic monocyclic or multicyclic ring system of about 6 to
about 10 carbon atoms. The aryl is optionally substituted with one ormore C1-C20
alkyl, alkoxy or haloalkyl groups. Representative aryl groups include phenyl or
naphthyl, or substituted phenyl or substituted naphthyl.
"Arylalkyl" means an aryl-alkylene- group where aryl and alkylene are defined
herein. Representative arylalkyl groups include benzyl, phenylethyl, phenylpropyl, 1-
naphthylmethyl, and the like. Benzyl is preferred.
"Diallyl-N,N-disubstituted ammonium halide monomer" means a monomer of
formula
(H2C=CHCH2)2N+R3R4X-
wherein R3 and R4 are independently C1-C20 alkyl, aryl or arylalkyl and X is an anionic
counterion. Representative anionic counterions include halogen, sulfate, nitrate,
phosphate, and the like. A preferred anionic counterion is halogen. Halogen is
preferred. A preferred diallyl-N,N-disubstituted ammonium halide monomer is
diallyldimethylammonium chloride.
"Halogen" means fluorine, chlorine, bromine or iodine.
"Monomer" means a polymerizable allylic, vinylic or acrylic compound. The
monomer may be anionic, cationic, nonionic or zwitterionic. Vinyl monomers are
preferred, acrylic monomers are more preferred.
Representative non-ionic, water-soluble monomers include acrylamide,
methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-
isopropylacrylamide, N-vinylformamide,
N-vinylmethylacetamide, N-vinyl pyrrolidone, hydroxyethyl methacrylate,
hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-t-
butylacrylamide, N-methylolacrylamide, vinyl acetate, vinyl alcohol, and the like.

Representative anionic monomers include acrylic acid, and it's salts, including,
but not limited to sodium acrylate, and ammonium acrylate, methacrylic acid, and it's
salts, including, but not limited to sodium methacrylate, and ammonium methacrylate,
2-acrylamido-2-methylpropanesulfonic acid (AMPS), the sodium salt of AMPS,
sodium vinyl sulfonate, styrene sulfonate, maleic acid, and it's salts, including, but not
limited to the sodium salt, and ammonium salt, sulfonate, itaconate, sulfopropyl
acrylate or methacrylate or other water-soluble forms of these or other polymerisable
carboxylic or sulphonic acids. Sulfomethylated acrylamide, allyl sulfonate, sodium
vinyl sulfonate, itaconic acid, aerylamidomethylbutanoic acid, fumaric acid,
vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, sulfomethylated
acrylamide, phosphonomethylated acrylamide, itaconic anhydride, and the like.
Representative cationic monomers include allyl amine, vinyl amine,
dialkylaminoalkyl acrylates and methacrylates and their quaternary or acid salts,
including, but not limited to, dimethylaminoethyl acrylate methyl chloride quaternary
salt (DMAEA-MCQ), dimethylaminoethyl acrylate methyl sulfate quaternary salt,
dimethyaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl
acrylate sulfuric acid salt, dimethylaminoethyl acrylate hydrochloric acid salt,
dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl
methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl
chloride quaternary salt, dimethylaminoethyl methacrylate sulfuric acid salt,
dimethylaminoethyl methacrylate hydrochloric acid salt, dialkylaminoalkylacrylamides
or methacrylamides and their quaternary or acid salts such as
acrylamidopropyltrimethylammonium chloride, dimethylaminopropyl acrylamide
methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfuric acid salt,
dimethylaminopropyl acrylamide hydrochloric acid salt,
methacrylamidopropyltrimethylammonium chloride, dimethylaminopropyl
methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide
sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt,
diethylaminoethylacrylate, diethylammoethylrnethacrylate, diallyldiethylammonium

chloride and diallyldimethyl ammonium chloride (DADMAC). Alkyl groups are
generally C1-4 alkyl.
"Zwitterionic monomer" means a polymerizable molecule containing cationic
and anionic (charged) functionality in equal proportions, so that the molecule is net
neutral overall. Representative zwitterionic monomers include N,N-dimethyl-N-
acryloyloxyethyl-N-(3-sulfopropyl)-ammonium betaine, N,N-dimetiiyl-N-
acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine,
N,N-dimethyl-N-acrylamidopropyl-N-(3-sulfopropyl)-ammonium betaine, N,N-
dimethyl-N-acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine, 2-
(methylthio)ethyl methacryloyl-S-(sulfopropyl)-sulfonium betaine, 2-[(2-
acryloylethyl)dimethylammonio]ethyl 2-methyl phosphate,
2-(acryloyloxyethyl)-2' -(trimethylammonium)ethyl phosphate,
[(2-acryloylethyl)dimethylammonio]methyl phosphonic acid, 2-methacryloyloxyethyl
phosphorylcholine (MPC), 2-[(3-acrylamidopropyl)dimethylammonio]ethyl 2'-
isopropyl phosphate (AAPI), 1-vinyl-3-(3-sulfopropyl)imidazolium hydroxide, (2-
acryloxyethyl) carboxymethyl methylsulfonium chloride, l-(3-sulfopropyl)-2-
vinylpyridinium betaine, N-(4-sulfobutyl)-N-methyl-N,N-diallylamine ammonium
betaine (MDABS), N,N-diallyl-N-methyl-N-(2-sulfoethyl) ammonium betaine, and the
like.
"Papermaking process" means a method of making paper products from pulp
comprising forming an aqueous cellulosic papermaking furnish, draining the furnish to
form a sheet and drying the sheet. The steps of forming the papermaking furnish,
draining and drying may be carried out in any conventional manner generally known to
those skilled in the art. Conventional microparticles, alum, cationic starch or a
combination thereof may be utilized as adjuncts with the polymer treatment of this
invention, though it must be emphasized that no adjunct is required for effective
dewatering activity.

Preferred Embodiments
The aldehyde-functionalized polymers according to this invention are prepared
by reacting a polymer comprising amino or amido groups with one or more aldehydes.
The polymer comprising amino or amide groups can have various architectures
including linear, branched, star, block, graft, dendrimer, and the like.
Preferred polymers comprising amino or amido groups include polyamines and
polyamides. The polyamides and polyamides may be prepared by copolymerizing
monomers under free radical forming conditions using any number of techniques
including emulsion polymerization, dispersion polymerization and solution
polymerization.
Polyamines may also be prepared by modification of a pre-formed polyamide,
for example by hydrolysis of acrylamide-vinylformamide copolymer using acid or base
as described in U.S. Patent Nos. 6,610,209 and 6,426,383.
Polyaminoamides may also be prepared by direct amidation of polyalkyl
carboxylic acids and transamidation of copolymers containing carboxylic acid and
(meth)acrylamide units as described in U.S. Patent No. 4,919,821.
"Emulsion polymer" and "latex polymer" mean a polymer emulsion comprising
an aldehyde-functionalized polymer according to this invention in the aqueous phase, a
hydrocarbon oil for the oil phase and a water-in-oil emulsifying agent. Inverse
emulsion polymers are hydrocarbon continuous with the water-soluble polymers
dispersed within the hydrocarbon matrix. The inverse emulsion polymers are then
"inverted" or activated for use by releasing the polymer from the particles using shear,
dilution, and, generally, another surfactant. See U.S. Pat. No. 3,734,873, incorporated
herein by reference. Representative preparations of high molecular weight inverse
emulsion polymers are described in U. S. Patent nos. 2,982,749; 3,284,393; and
3,734,873. See also, Hunkeler, et al., "Mechanism, Kinetics and Modeling of the
Inverse-Microsuspension Homopolymerization of Aaylamide, "Polymer, vol. 30(1),
pp 127-42 (1989); and Hunkeler et al., "Mechanism, Kinetics and Modeling of Inverse-
Microsuspension Polymerization: 2. Copolymerization of Aaylamide with Quaternaiy
Ammonium Cationic Monomers, " Polymer, vol. 32(14), pp 2626-40 (1991).

The aqueous phase is prepared by mixing together in water one or more water-
soluble monomers, and any polymerization additives such as inorganic salts, chelants,
pH buffers, and the like.
The oil phase is prepared by mixing together an inert hydrocarbon liquid with
one or more oil soluble surfactants. The surfactant mixture should have a low
hydrophilic-lypophilic balance (HLB), to ensure the formation of an oil continuous
emulsion. Appropriate surfactants for water-in-oil emulsion polymerizations, which
are commercially available, are compiled in the North American Edition of
McCutcheon's Emulsifiers & Detergents. The oil phase may need to be heated to
ensure the formation of a homogeneous oil solution.
The oil phase is then charged into a reactor equipped with a mixer, a
thermocouple, a nitrogen purge tube, and a condenser. The aqueous phase is added to
the reactor containing the oil phase with vigorous stirring to form an emulsion. The
resulting emulsion is heated to the desired temperature, purged with nitrogen, and a
free-radical initiator is added. The reaction mixture is stirred for several hours under a
nitrogen atmosphere at the desired temperature. Upon completion of the reaction, the
water-in-oil emulsion polymer is cooled to room temperature, where any desired post-
polymerization additives, such as antioxidants, or a high HLB surfactant (as described
in U.S. Patent 3,734,873) may be added.
The resulting emulsion polymer is a free-flowing liquid. An aqueous solution
of the water-in-oil emulsion polymer can be generated by adding a desired amount of
the emulsion polymer to water with vigorous mixing in the presence of a high-HLB
surfactant (as described in U.S. Patent 3,734,873).
"Dispersion polymer" polymer means a water-soluble polymer dispersed in an
aqueous continuous phase containing one or more organic or inorganic salts and/or one
or more aqueous polymers. Representative examples of dispersion polymerization of
water-soluble polymers in an aqueous continuous phase can be found in U.S. Patent
Nos. 5,605,970; 5,837,776; 5,985,992; 4,929,655; 5,006,590; 5,597,859; and 5,597,858
and in European Patent Nos. 183,466; 657,478; and 630,909.

In a typical procedure for preparing a dispersion polymer, an aqueous solution
containing one or more inorganic or organic salts, one or more water-soluble
monomers, any polymerization additives such as processing aids, chelants, pH buffers
and a water-soluble stabilizer polymer is charged to a reactor equipped with a mixer, a
thermocouple, a nitrogen purging tube, and a water condenser. The monomer solution
is mixed vigorously, heated to the desired temperature, and then a free radical initiator
is added. The solution is purged with nitrogen while maintaining temperature and
mixing for several hours. After this time, the mixture is cooled to room temperature,
and any post-polymerization additives are charged to the reactor. Water continuous
dispersions of water-soluble polymers are free flowing liquids with product viscosities
generally 100-10,000 cP, measured at low shear.
In a typical procedure for preparing solution polymers, an aqueous solution
containing one or more water-soluble monomers and any additional polymerization
additives such as chelants, pH buffers, and the like, is prepared. This mixture is
charged to a reactor equipped with a mixer, a thermocouple, a nitrogen purging tube
and a water condenser. The solution is mixed vigorously, heated to the desired
temperature, and then one or more free radical polymerization initiators are added. The
solution is purged with nitrogen while maintaining temperature and mixing for several
hours. Typically, the viscosity of the solution increases during this period. After the
polymerization is complete, the reactor contents are cooled to room temperature and
then transferred to storage. Solution polymer viscosities vary widely, and are
dependent upon the concentration and molecular weight of the active polymer
component.
The polymerization reactions are initiated by any means which results in
generation of a suitable free-radical. Thermally derived radicals, in which the radical
species results from thermal, homolytic dissociation of an azo, peroxide,
hydroperoxide and perester compound are preferred. Especially preferred initiators are
azo compounds including 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-
azobis[2-(2-imidazolin-2-yl)propane]jdihydrochloride, 2,2'-azobis(isobutyronitrile)
(AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (AIVN), and the like.

The polymerization processes can be carried out as a batch process or in steps.
In a batch process, all of the reactive monomers are reacted together, whereas in a step
or semi-batch process, a portion of the reactive monomer is withheld from the main
reaction and added over time to affect the compositional drift of the copolymer or the
formation of the dispersion particles.
The polymerization and/or post polymerization reaction conditions are selected
such that the resulting polymer comprising amino or amido groups has a molecular
weight of at least about 1,000 g/mole, preferably about 2,000 to about 10,000,000
g/mole.
The polymer comprising amino or amido groups is then functionalized by
reaction with one or more aldehydes. Suitable aldehydes include any compound
containing at least one aldehyde
(-CHO) functional group having sufficient reactivity to react with the amino or amido
groups of the polymer. Representative aldehydes include formaldehyde,
paraformaldehyde, glutaraldehyde, glyoxal, and the like. Glyoxal is preferred.
The aldehyde-functionalized polymer is prepared by reacting the polyamide or
polyamine with aldehyde at a pH between 4 to 12. The total concentration of polymer
backbone plus aldehyde is between about 5 to about 35 weight percent. Generally, an
aqueous solution of the polymer backbone is prepared for better reaction rate control
and increased product stability. The pH of the aqueous polymer backbone solution is
increased to between about 4 to about 12. The reaction temperature is generally about
20 to about 80 °C preferably about 20 to about 40 °C. An aqueous aldehyde solution is
added to the aqueous polymer backbone solution with good mixing to prevent gel
formation. After the addition of aldehyde the pH is adjusted to about 4 to about 12 to
achieve the desired reaction rate. After the adjustment of the pH generally the amount
of monoreacted amide/amine is optimum for the given ratio of aldehyde to
amide/amine and the amount of direacted amide/amine is low. The rate of viscosity
increase is monitored during the reaction using a Brookfield viscometer. A viscosity
increase of 0.5 cps indicates an increase in polymer molecular weight and an increase
in the amount of direacted amide/amine. The amount of monoreacted amide/amine is

generally maintained during the viscosity increase but the amount of direacted
amide/amine increases with viscosity. Generally, the desired viscosity increase
corresponds to a desired level of monoreacted amide/amine, direacted amide/amine
and molecular weight. The rate of reaction depends on the temperature, total
concentration of polymer and aldehyde, the ratio of aldehyde to amide/amine
functional groups and pH. Higher rates of glyoxylation are expected when the
temperature, total concentration of polymer and aldehyde, the ratio of aldehyde to
amide/amine functional groups or pH is increased. The rate of reaction can be slowed
down by decreasing the total concentration of polymer and aldehyde, temperature, the
ratio of aldehyde to amide/amine functional groups or pH (to between about 2 to about
3.5). The amount of unreacted aldehyde at the end of the reaction increases as the ratio
of aldehyde to amide/amine functional groups is increased. However, the total amount
of monoreacted and direacted amide/amine becomes larger.
For example, reaction of a 95/5 mole percent diallyldimethylammonium
chloride/acrylamide copolymer with glyoxal in a molar ratio of 0.4 to 1 glyoxal to
acrylamide results in a 95/5 mole percent acrylamide/DADMAC copolymer with about
15 to 23 mole percent monoreacted and direacted acrylamide and with about 60 to 70
mole percent total unreacted glyoxal at the target product viscosity and molecular
weight. A molar ratio of 0.8 to 1 glyoxal to acrylamide results in a 95/5 mole percent
acrylamide/DADMAC copolymer with about 22 to 30 mole percent monoreacted and
direacted acrylamide and with about 70 to 80 mole percent total unreacted glyoxal at
the target product viscosity and molecular weight.
The product shelf stability depends on the storage temperature, product
viscosity, total amount of reacted amide/amine, total concentration of polymer and
aldehyde, the ratio of aldehyde to amide/amine functional groups and pH. Generally,
the pH of the product is maintained at a low pH (2 to 3.5) and the total concentration of
polymer and aldehyde is optimized to extend shelf stability.
The reaction conditions are selected such that at least about 15 mole percent,
preferably at least about 20 mole percent of the amino or amido groups in the polymer
react with the aldehyde to form the aldehyde-functionalized polymer. The resulting

aldehyde-functionalized polymers have a weight average molecular weight of at least
about 100,000 g/mole, preferably at least about 300,000 g/mole.
In a preferred aspect of this invention, the aldehyde functionalized polymer is
an aldehyde functionalized polyamide.
In another preferred aspect, the aldehyde functionalized polyamide is an
aldehyde-functionalized polymer comprising 100 mole percent of one or more
nonionic monomers.
In another preferred aspect, the aldehyde functionalized polyamide is an
aldehyde functionalized copolymer comprising about 5 to about 99 mole percent of one
or more acrylamide monomers and about 95 mole percent to about 1 mole percent of
one or more cationic, anionic or zwitterionic monomers, or a mixture thereof.
Copolymers prepared from nonionic monomers and cationic monomers
preferably have a cationic charge of about 1 to about 50 mole percent, more preferably
from about 1 to about 30 mole percent.
Copolymers prepared from nonionic monomers and anionic monomers
preferably have an anionic charge of about 1 to about 50 mole percent, more preferably
from about 1 to about 30 mole percent.
Amphoteric polymers preferably have an overall positive charge. Preferred
amphoteric polymers are composed of up to about 40 mole percent cationic monomers
and up to about 20 mole percent anionic monomers. More preferred amphoteric
polymers comprise about 5 to about 10 mole percent cationic monomers and about 0.5
to about 4 mole percent anionic monomers.
Zwitterionic polymers preferably comprise 1 to about 95 mole percent,
preferably 1 to about 50 mole percent zwitterionic monomers.
In a preferred aspect of this invention the aldehyde-functionalized polyamide is
an aldehyde functionalized copolymer comprising about 1 to about 99 mole percent of
one or more acrylamide monomers and about 99 mole percent to about 1 mole percent
of one or more cationic, anionic or zwitterionic monomers, or a mixture thereof.
In another preferred aspect, the aldehyde functionalized polyamide is an
aldehyde functionalized copolymer comprising about 50 to about 99 mole percent of

one or more acrylamide monomers and about 50 to about 1 mole percent of one or
more cationic monomers.
In another preferred aspect, the aldehyde fimctionalized polymer is a copolymer
comprising about 50 to about 99 mole percent of one or more acrylamide monomers
and about 50 to about 1 mole percent of one or more cationic monomers wherein the
copolymer is fimctionalized with glyoxal.
In another preferred aspect, the cationic monomer is a diallyl-N,N-disubstituted
ammonium halide monomer.
In another preferred aspect, about 20 to about 50 mole percent of the amide
groups of the copolymer have reacted with glyoxal.
In another preferred aspect, the nonionic monomer is acrylamide and the
diallyl-N,N-disubstituted ammonium halide monomer is diallyldimethylammonium
chloride.
In another preferred aspect, the fimctionalized polymer is a copolymer
comprising about 70 to about 99 mole percent of acrylamide and about 1 to about 30
mole percent of diallyldimethylammonium chloride fimctionalized with glyoxal.
In another preferred aspect, about 20 to about 26 mole percent of the amide
groups of the copolymer have reacted with glyoxal.
The aldehyde-fimctionalized polymers are useful for dewatering all grades of
paper and paperboard with board grades and fine paper grades being preferred.
Recycle board grades using OCC (old corrugated containers) with or without mixed
waste have been particularly responsive.
Useful increases in dewatering can be achieved with aldehyde-functionalized
polymer doses in the range 0.05 to 15.0 lb polymer/ton of dry fiber with best results
normally achieved in the range 0.5 to 3.0 lb/ton depending on the particular
papermaking circumstances (papermachine equipment and papermaking raw materials
used).
The aldehyde fimctionalized polymers of the invention can be added in
traditional wet end locations used for conventional wet end additives. These include to
thin stock or thick stock. The actual wet end location is not considered to be critical,

but the aldehyde-functionalized polymers are preferably added prior to the addition of
other cationic additives. Because the aldehyde-functionalized polymers are believed to
act as pressing aids, their addition to the wet end is not necessary, and the option of
adding them just prior to the press section after the formation of the sheet Gan also be
practiced. For example, the polymer can be sprayed on the wet web prior to entering
the press section, and this can be a preferred mode of addition to reduce dosages or the
effects of interferences which might occur in the wet end. Other traditional wet end
additives can be used in combination with the aldehyde functionalized polymers.
These include retention aids, strength'additives such as starches, sizing agents, and the
like.
When using aldehyde-functionalized polymers as described herein having net
anionic charge, a method of fixing the polymer to the fiber is needed. This fixing is
typically accomplished by using cationic materials in conjunction with the polymers.
Such cationic materials are most frequently"coagulants, either inorganic (e.g. alum,
polyaluminum chlorides, iron chloride or sulfate, and any other cationic hydrolyzing
salt) or organic (e.g. p-DADMACs, EPI/DMAs, PEIs, modified PEIs or any other high
charged density low to medium molecular weight polymers). Additionally, cationic
materials added for other purposes like starch, wet strength, or retention additives can
also serve to fix the anionic polymer. No additional additives are need to fix cationic
aldehyde-functionalized polymers to the filler. _. _
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.
Example 1
Preparation of 95/5 mole % Acrylamide/DADMAC copolymer.
To a 1500-mL reaction flask fitted with a mechanical stirrer, thermocouple,
condenser, nitrogen purge tube, and addition port is added 116.4 g of deionized or soft
water, 26.3 g of phosphoric acid, 63.8 g of a 62% aqueous solution of diallyldimethyl
ammonium chloride (Nalco Company, Naperville, IL), 7.6 g of sodium formate, and

0.09 g of ethylenediaminetetraacetic acid, tetra sodium salt. The reaction mixture is
stirred at 400 rpm and the pH adjusted to 4.7 to 4.9 using 17.3 g of aqueous 50 %
sodium hydroxide solution. The resulting mixture is heated to 100 ° C and purged with
nitrogen at 50 mL/min. Upon reaching 100 °C, 17.6 g of a 25.0% aqueous solution of
ammonium persulfate is added to the reaction mixture over a period of 135 minutes.
Five minutes after starting the ammonium persulfate addition, 750.9 g of a 49.5%
aqueous solution of acrylamide is added to the reaction mixture over a period of 120
minutes. The reaction is held at 100 °C for 180 minutes after ammonium persulfate
addition. The reaction mixture is then cooled to ambient temperature and the pH is
adjusted to 5.2 to 5.8 using 50 % aqueous sodium hydroxide solution or concentrated
sulfuric acid. The product is a viscous, clear to amber solution. The product has a
molecular weight of about 20,000 g/mole.
Example 2
Glyoxylation of 95/5 mole % Acrylamide/DADMAC copolymer with 0.8 to 1 glyoxal
to acrylamide mole ratio at 9.0 % actives (total glyoxal and polymer).
To a 2000-mL reaction flask fitted with a mechanical stirrer, thermocouple,
condenser, addition port and sampling valve at the bottom of the reactor is added 238.0
g of a 41% aqueous solution of 95/5 mole % acrylamide/DADMAC copolymer,
prepared as in Example 1, and 1304.0 g of deionized or soft water. The polymer
solution is stirred at 400 rpm. The pH of the solution is adjusted to 8.8 to 9.1 by
adding 5.8 g of 50% aqueous sodium hydroxide solution. The reaction temperature is
set at 24 to 26 °C. Glyoxal (143.0 g of a 40% aqueous solution) is added to the
reaction mixture over 20 to 30 minutes. The Brookfield viscosity (Brookfield
Programmable LVDV-II+ Viscometer, LV # 1 spindle at 60 rpm, Brookfield
Engineering Laboratories, Inc, Middleboro, MA) of the reaction mixture is about 4 to 5
cps after glyoxal addition. The pH of the reaction mixture is adjusted to 7.5 to 8.8
using 10 % aqueous sodium hydroxide (25 g) added over 20 to 30 minutes. The
Brookfield viscosity (Brookfield Programmable LVDV-II+ Viscometer, LV # 1 spindle
at 60 rpm, Brookfield Engineering Laboratories, Inc, Middleboro, MA) of the reaction

mixture is about 4 to 5 cps after sodium hydroxide addition. The pH of the reaction
mixture is maintained at about 7.0 to 8.8 at about 24 to 26 °C with good mixing. The
Brookfield viscosity is monitored and upon achieving the desired viscosity increase of
greater than or equal to 1 cps (5 to 200 cps, >100,000 g/mole) the pH of the reaction
mixture is decreased to 2 to 3.5 by-adding sulfuric acid (93 %) to substantially decrease
the reaction rate. The rate of viscosity increase is dependent on the reaction pH and
temperature. The higher the pH of the reaction mixture the faster the rate of viscosity
increase. The rate of viscosity increase is controlled by decreasing the pH of the
reaction mixture. The product is a clear to hazy, colorless to amber, fluid with a
Brookfield viscosity greater than or equal to 5 cps. The resulting product is more
stable upon storage when the Brookfield viscosity of the product is less than 40 cps and
when the product is diluted with water to lower percent actives. The product can be
prepared at higher or lower percent total actives by adjusting the desired target product
viscosity. NMR analysis of the samples prepared indicate that about 70 to 80 % of the
glyoxal is unreacted and 15 to 35 mole percent of the acrylamide units reacted with
glyoxal to from monoreacted and direacted acrylamide.
Example 3
Dewatering effectiveness of representative aldehyde-functionalized polymers.
The dewatering effects of glyoxalated DADMAC/Acrylamide polymers
prepared with glyoxal to acrylamide mole ratios (here after referred to as the G/A ratio)
of 0.1, 0.2, 0.4 and 0.8 are evaluated through paper machine trials. The relative
performance of polymers prepared using the 0.1, 0.2, and 0.8 G/A ratios are compared
to the polymer prepared with the 0.4 mole ratio. The trials are run on a dual headbox
Fourdrinier papermachine using 100% OCC furnish manufacturing recycle linerboard
and corrugating medium. Actual papermachine conditions varied depending on the
specific grade of paperboard being made. In all cases, a retention program of
polyaluminum chloride fed to the thick stock and a cationic flocculant fed to the thin
stock is used. For linerboard grades, ASA sizing fed to the thin stock is also present.
The glyoxalated acrylamide polymers are applied through a spray boom to the

underside of he top ply prior to meshing with the bottom ply, although earlier trials
demonstrated the dewatering effect could also be achieved by wet-end thick or thin
stock addition.
The dewatering effect of the polymers is evaluated on the basis of steam
pressure changes in the machine dryer section which are provided through the mills
DCS (distributive control system) computer system. The sheet moisture at the reel is
measured on-line and is maintained by adjustment of the steam pressure (a measure of
steam usage or energy consumption). Lower sheet moisture at the reel reflects a lower
sheet moisture going into the dryer section or equivalently, better dewatering through
the machine sections preceding the dryer section. The lower steam demand, as
measured by pressure, then reflects improved dewatering. If the steam pressure in
these sections drops to a level where the operator feels comfortable that normal swings
in steam demand can be handled, then he will increase the machine speed manually.
When changes in polymer type or dose are made, the steam pressure from one of the
steam sections is followed closely to see if any change occurs, with proper
consideration given to changes in production rates when they occur. The initial effect
of a drier sheet is observed by lower percent moisture detected at the reel. However,
this drop in percent moisture is short lived because of the automatic regulation leaving
only the steam reduction as a permanent reminder of any dewatering effect produced.
Many factors other than addition of the aldehyde-functionalized polymer also affect the
sheet moisture, but most, like stock changes, occur over a longer time frame than the
steam reduction effect caused by the polymer additive, particularly when applied on the
table through spray application. Consequently, the steam reduction is a better indicator
of polymer dewatering than the average production rate or machine speed, as these
measures are more easily confounded with the other factors which effect machine
speed.
Example 3a
Comparison of polymer with a 0.1 G/A ratio with polymer having a 0.4 G/A ratio.
Comparison of these two polymers is conducted on 42 lb linerboard in the
absence of wet-end starch. After a baseline is established with the 0.4 G/A ratio

polymer at 2.0 Ib/ton, the 0.1 G/A ratio polymer is substituted at 2.2 lb/ton. Almost
immediately, the sheet at the reel is consistently observed to be wetter and the steam
demand increases to maximum in about 1 hr which necessitates the re-introduction of
the 0.4 G/A ratio polymer to prevent slowing down the paper machine. To regain
control of the machine, 3 lb/ton of the 0.4 G/A ratio polymer is needed, and its addition
results in a dramatic reduction in steam pressure, 12 psi in 15 min. Subsequently, a
baseline with the 0.4 G/A ratio polymer is reestablished at 2 lb/ton whereupon
substitution with 0.1 G/A ratio polymer at the higher dose of 3.4 lb/ton is initiated. At
this much higher dose, the steam pressure progressively increases over a period of
about an hour again to the point where it becomes necessary to revert back to the 0.4
G/A ratio polymer to prevent slowing the machine. Again, with the 0.4 G/A ratio
polymer added at 3.0 lb/ton the steam pressure is quickly reduced, 12 psi in 15 min.
and this reduction could be maintained even when the 0.4 G/A ratio polymer's dose is
reduced to 2 lb/ton. The 0.1 G/A ratio polymer could not maintain the steam pressure,
and therefore the machine speed, achieved by 0.4 G/A ratio polymer even at a dose
70% higher. No change in the strength specifications for this grade (Mullen and Scott
bond) could be detected when the 0.1 G/A ratio polymer is substituted for the 0.4 G/A
ratio polymer.
Example 3b
Comparison of polymer with a 0.2 G/A ratio with polymer having a 0.4 G/A ratio.
Comparison of these two polymers is conducted on 35 lb linerboard with 5
lb/ton wet-end starch fed to the thick stock. After a baseline is established with the 0.4
G/A ratio polymer at 2.0 lb/ton, the 0.2 G/A ratio polymer is substituted at 2.2 lb/ton.
At this dosage, a modest increase in steam pressure of 5 psi is measured over a period
of about the hour. Reintroduction of the 0.4 G/A ratio polymer resulted in an
immediate decrease in reel moisture and a quick decline in steam pressure of 3 psi in
10 min. Switching back to the 0.2 G/A ratio polymer at 2.2 lb/ton at this point keeps
the steam reasonably constant for about an hour with only a 2 psi increase. Again,
reintroduction of 2 lb of the 0.4 G/A ratio polymer results in a quick decline in steam

pressure of 8 psi in 20 min. indicative of improve dewatering. Based on these results,
the 0.2 G/A ratio polymer certainly demonstrates dewatering ability, but even at a 10%
increase in dosage, it could not maintain the pressure achievable with the 0.4 G/A ratio
polymer. Additionally, unlike the 0.1 G/A ratio polymer, the 0.2 G/A ratio polymer is
capable of keeping the machine running at the desired speed although at increased
steam demand and dosage relative to the 0.4 G/A ratio polymer. The trial results with
these three polymers indicated that the 0.4 G/A ratio polymer gives better dewatering
than the 0.2 G/A ratio polymer and it in turn gives better dewatering than the 0.1 G/A
ratio polymer. No change in the strength specifications for this grade (STFI) could be
detected when the 0.2 G/A ratio polymer is substituted for the 0.4 G/A ratio polymer.
Example 3c
Comparison of polymer with a 0.8 G/A ratio with polymer having a 0.4 G/A ratio.
Based on the discovery that increasing the G/A ratio in the preparation of the
polymers increases dewatering, an even higher G/A ratio of 0.8 is prepared and
evaluated on the same papermachine. Comparison of the 0.8 G/A ratio polymer with
the 0.4 G/A ratio polymer is conducted on 33 lb corrugating medium in the absence of
wet-end starch. Addition of the 0.4 G/A ratio polymer at 2.0 lb/ton results in a very
good reduction in steam pressure of 21 psi after about 2 hours at which time 1.5 lb/ton
of the 0.8 G/A ratio polymer replaces the 2 lb/ton of 0.4 G/A ratio polymer. Even with
the 25%1reduction in dose, the addition of the 0.8 G/A ratio polymer results in an even
further reduction in steam pressure by 3 psi and a dramatic increase in steam pressure
of 12 psi occurs in 0.5 hour when it is removed. Further trialing is conducted on 26 lb
corrugating medium in the absence of wet-end starch. Starting again with 2.0 lb/ton of
0.4 G/A ratio polymer to establish the baseline, a substitution of 2.0 lb/ton of 0.8 G/A
ratio polymer results in a drop in steam pressure of 7 psi in 60 min., which further
decreases by 4 psi when the dosage is increased to 3 lb/ton in 10 min. Reducing the
0.8 G/A ratio polymer to only 1.0 lb/ton relative to the 3 lb/ton results in an increase in
steam pressure, but it remains 8 psi below the 2.0 lb/ton 0.4 G/A ratio polymer value
even with an increase in machine speed of 30 ft/min. Based on these trial results the

0.8 G/A ratio polymer appears to yield equivalent dewatering at a dose 25 to 50% less
than required by the 0.4 G/A ratio polymer. The strength specification for both
medium grades (Concorra) made with the 0.8 G/A ratio polymer exhibit values equal
to or greater than those obtained with for the 0.4 G/A ratio polymer even though the
dosages are generally lower.
Based on these trial results, increasing the G/A ratio in the preparation of the
aldehyde-functionalized polymers is found to provide increased dewatering activity
with the preferred ratio being greater than 0.4.
Changes can be made in the composition, operation and arrangement of the
method of the invention described herein without departing from the concept and scope
of the invention as defined in the claims.

We CLAIM:
1. A method of enhancing the dewatering of a paper sheet on a paper
machine comprising adding to the paper sheet 0.05 lb/ton to 15 lb/ton,
based on dry fiber, of one or more aldehyde functionalized polymers
comprising amino or amido groups wherein at least 15 mole percent of the
amino or amido groups are functionalized by reacting with one or more
aldehydes and wherein the aldehyde functionalized polymers have a
weight average molecular weight of at least 100, 000 g/mole.
2. The method as claimed in claim 1, wherein the aldehyde functionalized
polymers are selected from the group consisting of aldehyde
functionalized polyamines and aldehyde functionalized polyamides.
3. The method as claimed in claim 1, wherein the aldehydes are selected
from formaldehyde, paraformaldehyde, glyoxal and glutaraldehyde.
4. The method as claimed in claim 1, wherein the aldehyde functionalized
polymer is an aldehyde functionalized polyamide.

5. The method as claimed in claim 4, wherein the aldehyde functionalized
polyamide is an aldehyde-functionalized polymer comprising 100 mole
percent of one or more nonionic monomers.
6. The method as claimed in claim 4, wherein the aldehyde functionalized
polyamide is an aldehyde functionalized copolymer comprising 5 to 99
mole percent of one or more acrylamide monomers and 95 mole percent
to 1 mole percent of one or more cationic, anionic or zwitterionic
monomers, or a mixture thereof.
7. The method as claimed in claim 6, wherein the aldehyde functionalized
polyamide is an aldehyde-functionalized copolymer comprising 1 to 50
mole percent of one or more anionic monomers and 99 to 50 mole percent
of one or more nonionic monomers.
8. The method as claimed in claim 6, wherein the aldehyde functionalized
polyamide is an aldehyde-functionalized copolymer comprising 1 to 30
mole percent of one or more anionic monomers and 99 to 70 mole percent
of one or more nonionic monomers.

9. The method as claimed in claim 6, wherein the aldehyde functionalized
copolymer is an aldehyde-functionalized amphoteric polymer comprising
up to 40 mole percent of one or more cationic monomers and up to 20
mole percent of one or more anionic monomers.
10. The method as claimed in claim 6, wherein the aldehyde functionalized
copolymer is an aldehyde-functionalized amphoteric polymer comprising 5
to 10 mole percent of one or more cationic monomers and 0.5 to 4 mole
percent of one or more anionic monomers.
11. The method as claimed in claim 6, wherein the aldehyde functionalized
copolymer is an aldehyde-functionalized zwitterionic polymer comprising 1
to 95 mole percent of one or more zwitterionic monomers.
12. The method as claimed in claim 6, wherein the aldehyde functionalized
copolymer is an aldehyde-functionalized zwitterionic polymer comprising 1
to 50 mole percent of one or more zwitterionic monomers.
13. The method as claimed in claim 6, wherein the aldehyde functionalized
polyamide is an aldehyde functionalized copolymer comprising 50 to 99
mole percent of one or more acryiamide monomers and 50 to 1 mole
percent of one or more cationic monomers.

14. The method as claimed in claim 13, wherein at least 20 mole percent of
the amide groups of the polyamide have reacted with aldehyde.
15. The method as claimed in claim 1, wherein the aldehyde functionalized
polymer is a copolymer comprising 50 to 99 mole percent of one or more
acrylamide monomers and 50 to 1 mole percent of one or more cationic
monomers wherein the copolymer is functionalized with glyoxal.
16. The method as claimed in claim 15 wherein the cationic monomer is a
diallyl-N,N-disubstituted ammonium halide monomer.
17. The method as claimed in claim 16, wherein 20 to 50 mole percent of the
amide groups of the copolymer have reacted with glyoxal.
18. The method as claimed in claim 16, wherein the nonionic monomer is
acrylamide and the diallyl-N,N-disubstituted ammonium halide monomer is
diallyldimethylammonium chloride.
19. The method as claimed in claim 18, wherein the aldehyde-functionalized
polymer has a molecular weight of at least 300,000 g/mole.

20. The method as claimed in claim 19, wherein the aldehyde-functionalized
polymer is a copolymer comprising 70 to 99 mole percent of acrylamide
and 1 to 30 mole percent of diallyldimethylammonium chloride
functionalized with glyoxal.
21. The method as claimed in claim 20, wherein 20 to 26 mole percent of the
amide groups of the copolymer have reacted with glyoxal.
22.The method as claimed in claim 21, wherein 0.5 lb/ton to 3 lb/ton, based
on dry fiber, of glyoxylated copolymer is added to the paper sheet.
23. The method as claimed in claim 1, wherein the aldehyde functionalized
polymer is sprayed onto the paper sheet prior to press dewatering.
24. The method as claimed in claim 1, wherein from 15 mole percent to 23
mole percent of the amino and/or amido groups are functionalized.
25. The method as claimed in claim 1, wherein from 20 mole percent to 26
mole percent of the amino and/or amido groups are functionalized.
26. The method as claimed in claim 1, wherein from 22 mole percent to 30
mole percent of the amino and/or amido groups are functionalized.

27. The method as claimed in claim 1, wherein from 20 mole percent to 50
mole percent of the amino and/or amido groups are functionalized.
28. The method as claimed in claim 1, wherein from 60 mole percent to 70
mole percent of the one or more aldehydes remain unreacted.
29. The method as claimed in claim 1, wherein from 70 mole percent to 80
mole percent of the one or more aldehydes remain unreacted.


A method of enhancing the dewatering of a paper sheet on a paper machine
comprising adding to the paper sheet 0.05 lb/ton to 15 lb/ton, based on dry fiber,
of one or more aldehyde functionalized polymers comprising amino or amido
groups wherein at least 15 mole percent of the amino or amido groups are
functionalized by reacting with one or more aldehydes and wherein the aldehyde
functionalized polymers have a weight average molecular weight of at least 100,
000 g/mole.

Documents:

01672-kolnp-2006-abstract.pdf

01672-kolnp-2006-claims.pdf

01672-kolnp-2006-correspondence others-1.1.pdf

01672-kolnp-2006-correspondence others.pdf

01672-kolnp-2006-correspondence-1.2.pdf

01672-kolnp-2006-description complete.pdf

01672-kolnp-2006-form 1.pdf

01672-kolnp-2006-form 2.pdf

01672-kolnp-2006-form 3.pdf

01672-kolnp-2006-form 5.pdf

01672-kolnp-2006-form-1-1.1.pdf

01672-kolnp-2006-form-26.pdf

01672-kolnp-2006-international publication.pdf

01672-kolnp-2006-international search authority report-1.1.pdf

01672-kolnp-2006-international search authority report.pdf

01672-kolnp-2006-pct form.pdf

1672-KOLNP-2006-ABSTRACT 1.1.pdf

1672-KOLNP-2006-CLAIMS 1.1.pdf

1672-kolnp-2006-correspondence-1.1.pdf

1672-kolnp-2006-correspondence.pdf

1672-KOLNP-2006-DESCRIPTION (COMPLETE) 1.1.pdf

1672-KOLNP-2006-EXAMINATION REPORT REPLY RECIEVED.pdf

1672-kolnp-2006-examination report.pdf

1672-KOLNP-2006-FORM 1 1.1.pdf

1672-kolnp-2006-form 13-1.1.pdf

1672-KOLNP-2006-FORM 13.pdf

1672-kolnp-2006-form 18.pdf

1672-KOLNP-2006-FORM 2 1.1.pdf

1672-kolnp-2006-form 26.pdf

1672-KOLNP-2006-FORM 3 1.1.pdf

1672-kolnp-2006-form 3-1.2.pdf

1672-kolnp-2006-form 5.pdf

1672-KOLNP-2006-FORM-27.pdf

1672-kolnp-2006-granted-abstract.pdf

1672-kolnp-2006-granted-claims.pdf

1672-kolnp-2006-granted-description (complete).pdf

1672-kolnp-2006-granted-form 1.pdf

1672-kolnp-2006-granted-form 2.pdf

1672-kolnp-2006-granted-specification.pdf

1672-kolnp-2006-intenational publication.pdf

1672-kolnp-2006-others-1.1.pdf

1672-KOLNP-2006-OTHERS.pdf

1672-KOLNP-2006-PCT SEARCH REPORT 1.1.pdf

1672-KOLNP-2006-PETITION UNDER RULE 137.pdf

1672-kolnp-2006-reply to examination report.pdf


Patent Number 246821
Indian Patent Application Number 1672/KOLNP/2006
PG Journal Number 11/2011
Publication Date 18-Mar-2011
Grant Date 16-Mar-2011
Date of Filing 16-Jun-2006
Name of Patentee NALCO COMPANY
Applicant Address 1601 DIEHL ROAD, NAPERVILLE, ILLINOIS 60563-1198
Inventors:
# Inventor's Name Inventor's Address
1 ST. JOHN, MICHAEL R 5414 EAST VIEW PARK, #1, CHICAGO, ILLINOIS 60615
2 ZAGALA, ANGELA P 3908 BLUEJAY LANE, NAPERVILLE, ILLINOIS 60564
PCT International Classification Number D21H 17/06,D21H17/55
PCT International Application Number PCT/US2005/001566
PCT International Filing date 2005-01-21
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/764,935 2004-01-26 U.S.A.