METHOD OF USING ALDEHYDE-FUNCTIONALIZED POLYMERS TO INCREASE
PAPERMACHINE PERFORMANCE AND ENHANCE SIZING
TECHNICAL FIELD
This invention relates generally to a novel composition and method for improving paper
and paperboard production. More specifically, the invention relates to a composition and method
for using aldehyde-functiortalized polymers as an emulsion stabilizer for sizing emulsions. The
invention has particular relevance to the application of such polymers in sizing emulsion
compositions as a replacement for traditional polymers.
BACKGROUND
Aldehyde-functionalized polymers based on polyaerykmide (and similar polymers as
described herein), provide a multitude of benefits for paper and paperboard manufacturing that
include temporary wet strength, dry strength, wet-web strength, Yankee dryer adhesives, and
increased press dewatering. Such polymers are most commonly used in the paper and
paperboard industry as additives to provide temporary wet strength and dry strength (see e.g.,
U.S. Patent No. to Coscia et al. 3,556,932, "Water-Soluble, Ionic, Glyoxalated, Vinylamide,
Wet-Strength Resing and Paper Made Therewith": Farley. C.E., "Glyoxalated Polyacrylarmde
Resin, pp. 45-61, in Wet-Strength Resins and Their Application, TAPPI Press; Atlanta, GA,
1994). More recent innovations in these types of polymers are disclosed in, for example, U.S.
Patent No. 7,641,766, "Method of Using Aldehyde-Functionalized Polymers to Enhance Paper
Machine Dewatering "
Addition of aldehyde-functionalized polymers to the papermaking process has been
conducted in many different ways to achieve the desired strength effects. Like ail wet-end
additives, such polymers are commonly fed directly to thin or thick stock of papermachine
systems prior to the sheet forming process, but other approaches such as spraying the additive
onto a wet sheet prior to the press section has also been practiced.
Sizing emulsions utilize polymers as emulsion stabilizers. Rather than being a variety of
aldehyde-functionalized as described herein, these polymeric emulsion stabilizers are typically
cationic vinyl addition polymers (See e.g., U.S. Patent No. 4,657,946) and polymers and
copolymers of diallykiialkylammonium halide that are substantially free of ammonium groups
attached to the polymer or copolymer by only one chemical bond have also been used (e.g., U.S.Patent No 6,491,790) Such polymers, however, do not provide the benefits of aldehyde-
functionalized polymers as discussed above
There thus exists an ongoing industrial need in the papermaking industry to develop
sizing formulations that improve sizing of paper and paperboard and also provide other
enhancements to papermaking process to reduce the need for multiple chemistries.
SUMMARY
This invention accordingly provides novel sizing mixtures to achieve improved sizing
along with other benefits as herein described to the papermaking process. In a preferred aspect
the disclosed invention is a composition comprising a sizing mixture having a stabilizing amount
of one or more aidehyde-fonctionalized polymers and a sizing amount of a sizing composition
In various embodiments, the polymers have a weight average molecular weight of at least about
50,000 g/mole and are stably present in an amount from about 2 wt% to about 33 wt%, based on
total weight of the composition.
In another aspect, the invention is a method of improving paper and paperboard
production and enhancing sizing through adding an effective amount of the disclosed sizing
mixture to the paper machine. The composition may be added any location or any point in the
papermaking process. In the method, the composition may be added to wet end locations used
for conventional wet end additives and/or into white water systems. In the method, the sizing
mixture may also be added to a thin stock, a thin stock approach line to a headbox, or a thick
stock in the papermaking process.
In another aspect, the invention is a method of producing a medium having cellulosic
fibers, wherein the method includes adding the disclosed sizing mixture to the medium at any
point in a papermaking process, the medium optionally having mineral filler(s).
It is an advantage of the invention to provide a composition and method of sizing that
increases the sizing effect of a sizing emulsion at fixed size dose.
It is another advantage of the invention to provide a composition and method of sizing
that reduces the amount of size used to achieve a given sizing response.
It is a further advantage of the invention to provide a composition and method that
improves water removal to increase papermachme speed for greater production.
It is yet another advantage of the invention to provide a composition and method that
reduces the amount of drying energy (i.e., steam demand) needed at fixed production rate.The foregoing has outlined rather broadly the features and technical advantages of the
present invention in order that the detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention will be described hereinafter
that form the subject of the claims of the invention. It should be appreciated by those skilled in
the art that the conception and the specific embodiments disclosed may be readily utilized as a
basis for modifying or designing other embodiments for carrying out the same purposes of the
present invention it should also be realized by those skilled in the art that such equivalent
embodiments do not depart from the spirit and scope of the invention as set forth in the appended
claims
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graphical representation of the effect of an embodiment of the invention on
reel moisture and steam pressure as a function of time.
Figure 2 shows Malvern Mastersizer distributions (vol% of emulsion particles with a
given diameter) for ASA emulsions prepared with an existing polymeric emulsifier containing a
surfactant and with the polymers of the invention
Figure 3 shows that the sizing effect on laboratory prepared handsheets as measured by
Hercules Sizing Test ("HST") method was unexpectedly better with glyoxalated polymer
emulsion.
DETAILED DESCRIPTION
It has been discovered unexpectedly that when one or more aldehyde-functionalized
polymers is used as the stabilizing agent for sizing mixtures dramatic increases in papermachine
dewatering, and thereby increases in paper production, are achieved. "Sizing mixtures" means,
according to embodiments, a sizing emulsion or a sizing dispersion, and "emulsion" and
"dispersion" are sometimes used interchangeably herein to refer to a sizing mixture. Whether a
particular sizing mixture is an emulsion or a dispersion will be apparent to those skilled in the art.
Such increases in paper production have not been found to occur when an equivalent amount of
one or more aldehyde-functionalized polymers is added to the paper furnish directly.
Additionally, significant increases in internal sizing were achieved using the disclosed aldehyde-
functionalized polymers as the stabilizing agent for the sizing emulsion when compared with
equal amounts of polymer stabilizers consisting of starch or low to medium molecular weightcationic acrylamide polymers (i.e., sizing emulsion stabilizers currently used in the papermaking
industry). The latter polymers are generally copolymers of acrylamide with common cationic
monomers (e.g., DADMAC, DMAEA*MCQ, and DMAEM*MCQ - see e.g., U.S. Patent No.
4 657,946, "Paper Sizing Method and Emulsion") but the use of other cationic polymers has also
been practiced and is generally well known.
In embodiments of the present invention, aldehyde-fimctionalized polymers for inclusion
in the composition and method are aldehyde-fimctionalized polymers prepared by reacting a
precursor or preformed polymer comprising one or more aldehyde-reactive moieties with one or
more aldehydes. Such polymers may have various architectures including linear, branched, star,
block, graft, dendrimer, the like, and any other suitable architecture. Preferred polymers
comprise those having amino or amido groups as the aldehyde-reactive moieties. These
precursor or preformed polymers may be derived from any suitable source and synthesized using
any suitable method. For example, the aldehyde-reactive polymers may be formed via emulsion,
dispersion, or solution polymerization and may contain nonionic, cationic, anionic, and
zwitterionic monomeric species with the polymer. Moreover, these monomelic species may be
present in any amount and in any combination in the polymer.
The following definitions are intended to be clarifying and are not intended to be limiting.
"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 methacryiamide. Acrylamide is more preferred.
"Aldehyde" means a compound containing one or more aldehyde (-CHO) groups or a
group capable of forming a reactive aldehyde group where the aldehyde groups are capable of
reacting with the aldehyde-reactive groups (e.g., amino or amido groups) of a polymer as
described herein. Representative aldehydes include formaldehyde, paraformaldehyde,
glutaraldehyde, glyoxal, the like, and any other suitable mono-functional or poly-functional
aldehyde Glyoxal is preferred."Aldehyde-functionalized" means the reaction product of a precursor polymer and an
aldehyde, where aldehyde-reactive group(s) of the precursor polymer has reacted with terminal
earbonyl group(s) of the aldehyde(s).
"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(0)NHY 1 where Y1 is selected from H,
alkyl, aryl, and arylalkyl.
"Amino group" means a group of formula -NHY 2 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 rnonomer(s). Representative amphoteric polymers
include copolymers composed of acrylic acid and DMAEA-MCQ, terpolymers composed of
acrylic acid, DADMAC and aerylamide, 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 or more C1 to 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 the
following formula,
wherein R3 and R 4 are independently Ci to C20 alkyl, aryl, or arylalkyl and X is an anionic
counterfoil. Representative anionic counterions include halogen, sulfate, nitrate, phosphate, andthe like, A preferred anionic counterfoil is halide. Chloride is preferred, A preferred diallyl-
N,N-disubstituted ammonium halide monomer is diallyldimethylammonium chloride.
"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,
"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 o f the Inverse-
Microsuspension Homopolymerization o f Acrylamide, " Polymer, vol. 30(1), pp 127-42 (1989);
and Hunkeler et al., "Mechanism, Kinetics and Modeling o f Inverse-Microsuspension
Polymerization: 2. Copolymerization o f Acrylamide with Quaternary Ammonium Cationie
Monomers, " Polymer, vol. 32(14), pp 2626-40 (1991)
"Monomer" means a polymerizable allylic, vinylie, or acrylic compound. The monomer
may be anionic, cationie, nonionic, or zwitterionic. Vinyl monomers are preferred, and acrylic
monomers are more preferred.
Representative non-ionic, water-soluble monomers include acrylamide, methacrylamide,
N,N-dimethylaciylamide, N,N-diethylacrylamide, N-isopropylacrylamide, N-vinyl formamide, N-
vmylmethylacetarnide, N-vinyl pyrrolidone, hydroxyethyl methacrylate, hydroxyethyl acrylate,
hydroxypropyl acrylate, hydroxypropyl methacrylate, N-t-butylacrylamide, N-
memylolacrylamide, vinyl acetate, vinyl alcohol, and the like.
Representative anionic monomers include acrylic acid, and its 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-
metbylpropanesulfonic acid (AMPS), the sodium salt of AMPS, sodium vinyl sulfonate, styrenesulfonate, 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, acrylamidomethylbutanoic acid, fumaric acid,
vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, sulfomethylated acrylamide,
phosphonomethylated acrylamide, itaconic anhydride, and the like.
Representative cationic monomers or mer units include monoallyl amine, diallyl amine,
vinyl amine, dialkvlaminoalkyl aerylates 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
aerylamidopropyltrimethylammonium chloride, dimethylammopropyl acrylamide methyl sulfate
quaternary salt, dimethylammopropyl acrylamide sulfuric acid salt, dimethylaminopropyl
acrylamide hydrochloric acid salt, methacrylamidopropyltrirnethylarnmomum chloride,
dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl
methacrylamide sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt,
diethylammoethylacrylate, diethylaminoethylmethacrylate, diallyldiethylammonium chloride and
diallyldimethyl ammonium chloride (DADMAC). Alkyl groups are generally C1 to C4 alkyl.
Representative zwitterionie monomers are those that are a polymerizable molecule
containing cationic and anionic (charged) functionality in equal proportions, so that the molecule
is net neutral overall. Specific representative zwitterionie monomers include N,N-dimethyl-N-
acryloyloxyethyl-N-(3-sulfopropyl)-ammonium betaine, N,N-dimethyl-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 phospbonic
acid, 2-methacryloyloxyethyl phosphoryleholine (MFC), 2-[(3-
acrylamidopropyl)dimethylammonio]ethyl 2'-isopropyl phosphate (AAPI), 1-vinyl-3-(3-sulfhpropyl)imidazolium hydroxide, (2-acryloxyethyl) carboxymethyl methylsulfonium chloride,
1-(3-sulfopropyl)-2-vinylpyridinium betaine, N-(4-sulfobutyl)-N-methyl-N, N-diallylamine
ammonium betaine (MDABS), N,N-diallyl-N-methyl-N-(2-sulfoethyI) ammonium betaine, and
the like.
"Papermaking process" means a method of making paper and paperboard products from
pulp comprising forming an aqueous cellulosic papermaking furnish (optionally, with mineral
fillers, such as calcium carbonates, clays, etc.), draining the furnish to form a sheet, and drying
the sheet It should be appreciated that any suitable furnish may be used. Representative
furnishes include, for example virgin pulp, recycled pulp, kraft pulp (bleached and unbleached),
sulfite pulp, mechanical pulp, polymeric plastic fibers, the like, any combination of the foregoing
pulps. The steps of forming the papennakirig furnish, draining and drying may be carried out in
any manner generally known to those skilled in the art. In addition to the sizing emulsions herein
described, other papermaking additives may be utilized as adjuncts with the polymer treatment of
this invention, though it must be emphasized that no adjunct is required for effective activity.
Such papermaking additives include, for example, retention aids (e.g., mieroparticles,
flocculants, polymeric and inorganic coagulants, etc.), wet and dry strength additives (e.g.,
cationic starches, polyamidoamine epichlorohydrin-based polymers), the like, and combinations
of the foregoing.
In an embodiment, polyammes are prepared by modification of a pre-formed polyamide,
for example by hydrolysis of aerylamide-vinylformamide copolymer using acid or base as
described in U.S. Patent Nos. 6,610,209 and 6,426,383.
In an embodiment, polyaminoamides may 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 .
In another embodiment, the preformed polymers are prepared as an emulsion or latex
polymer. For example, 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 oilphase 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 he 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).
In another embodiment, the preformed polymer used in the invention may be a dispersion
polymer 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 in the range of about 100 to about 10,000 cP measured at low
shear.
In another embodiment, the preformed or precursor polymers used in the invention are
solution polymers. 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 roomtemperature and then transferred to storage. Solution polymer viscosities vary widely, and are
dependent upon the concentration and molecular weight and structure of the active polymer
component.
Polymerization reactions are typically initiated by any means which results in generation
of a suitable free-radical Thermally derived radicals, in which the radical species results from
thermal, hemolytic dissociation of an azo, peroxide, hydroperoxide and perester compound are
preferred. Preferred initiators are azo compounds including 2,2'-azobis(2-amidinopropane)
dihydrochloride, 2,2 ' -azobis[2-(2-imidazolm-2 -yl )propane] dihydrochloride , 2,2' -
azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleroTiitrile) (AIVN), the like, and
combinations thereof. More preferred initiators include peroxides, such as ammonium persulfate,
sodium persulfate, the like, and combinations thereof.
Irs alternative embodiments, the polymerization processes can be carried out as a batch
process or in steps. In a representative hatch process, all of the monomers are reacted together
whereas in a step or semi-batch process, a portion of the 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 In a continuous process embodiment, all of the monomer is added
over time and affects the compositional drift differently.
The polymerization and/or post polymerization reaction conditions are selected such that
the resulting polymer comprising aldehyde-reactive moieties (i.e., the preformed or precursor
polymer) has a molecular weight of at least about 1,000 g/mole, preferably about 2,000 to about
10,000,000 g/mole. This polymer is then functionalized by reaction with one or more aldehydes.
Suitable aldehydes include any compound containing one or more aldehyde (-CHO) functional
groups (i.e. mono-functional or poly-functional aldehydes) and having sufficient reactivity to
react with the aldeyhyde-reactive moieties (e.g., amino or amido groups) of the polymer.
Representative aldehydes include formaldehyde, paraformaldehyde, glutaraldehyde, glyoxal, the
like, and any other suitable reactive aldehyde.
in an embodiment, the aldehyde-functionalized polymer is prepared by reacting the
polyamide or polyamine with one or more aldehydes at a pH between 4 to 12. The total
concentration of polymer backbone (i.e., preformed or precursor polymer having aldehyde-
reactive moieties) plus aldehyde is between about 2 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°C to about 80°Cpreferably about 20°C to about 40°C. An aqueous aldehyde solution is added to the aqueous
polymer backbone solution with good mixing to prevent gel formation. The rate of viscosity
increase is monitored using a Brookfield viscometer to follow the cross-linking reaction A
viscosity increase of 0.5 cps indicates an increase in polymer molecular weight and an increase in
polymer precursor cross-linking.
Generally, the desired viscosity increase corresponds to a desired level of activity which
generally reaches a maximum or a point of diminishing activity at a specific viscosity. 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 (in the case
where glyoxal is used as the aldehyde) 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 unreached aldehyde at the end of the reaction increases as
the ratio of aldehyde to amide/amine functional groups is increased.
In a preferred embodiment, the precursor polymer is prepared from a DADMAC and
acrylamide copolymer. Monomers of DADMAC and acrylamide may be present in weight-to-
weight ratios in the precursor polymer ranging from about 5/95 to about 95/5, respectively. This
precursor copolymer preferably has a weight average molecular weight of about 17,000 g/mole
and is reacted, for example, with glyoxal. The amount of glyoxal can vary but is usually added
to achieve a glyoxal to acrylamide mole ratio of 0.1 to 1.0 A preferred DADMAC/acrylamide
weight-to-weight ratio is 10/90.
The reaction conditions are preferably selected such that the molar ratio of aldehyde to
aldehyde-reactive moiety is from about 0.05 to about 1 5. This range of molar ratios may result
in a wide range of the aldehyde-reactive moieties of the precursor polymer being functionalized.
For example, from about 0.5 mole percent to greater than 40 mole percent of the aldehyde-
reactive moieties may be functionalized. Moreover, depending on the particular combination of
chosen aldehydes, from about 2 to about 40 percent or more of those reacted moieties may
participate in cross-links through the multifunctional aldehyde.
In one embodiment, 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 an embodiment, the aldehyde-functionalized polymer is formed from one or more
precursor polymers having aldehyde-reactive moieties selected from any combination of amines,
amides, and hydroxyls.
In another embodiment, the aldehyde-functionalized polymer is a copolymer comprising
about 1 to about 99 mole percent acrylamide monomers and about 95 mole percent to about 1
mole percent of one or more cationic, anionic, nonionic, or zwitterionie monomers, or a mixture
thereof. Copolymers prepared from nonionic aldehyde-reactive 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
aldehyde-reactive 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 Zwitterionie
polymers preferably comprise 1 to about 95 mole percent, preferably 1 to about 50 mole percent
zwitterionie monomers.
In another embodiment, the aldehyde-functionalized polymers are amphoteric polymers
thai 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 with the remaining monomers preferably being aldehyde-reactive 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 with the remaining monomers
preferably being aldehyde-reactive monomers.
In an embodiment, the disclosed polymer composition comprises from about 10 to about
90 mole percent aldehyde remains imreaeted In embodiments, the amount of aldehyde that
remains imreaeted may range (all ranges in mole percent) from about 10 to about 80, or from
about 10 to about 70, or from about 10 to about 60. In other embodiments, the amount of
aldehyde that remains unreacted is greater than about. 60 mole percent.
In embodiments of the present invention, any sizing agent may be used in the sizing
emulsion. Representative sizing agents include rosin size and water-insoluble hydrophobic
cellulose-sizing agents, such as alkyl ketene dimer ("AKD") or alkenyl succinic anhydride
(ASA) and mixtures thereof that are emulsified with the polymers of the invention in aqueous
solution. Such sizing agents prepared from various alkyl or alkenyl hydrocarbon chains, for
example, are well-known in the art.
in embodiments, AKD and rosin sizing agents are used as dispersions (i.e., solid
suspended in a liquid medium) rather than an emulsion. Such dispersions are sometimes used incircumstances where the melting point for certain AKDs and rosin sizing agents are lower than
the use temperature. The dispersions, for example, may be made by melting and emulsifying the
AKD or rosin sizing agent, allowing it to cool and solidify, and dispersing in a liquid solvent
Thus, in such embodiments, when the sizing agent is a solid at room temperature converting the
solid to a liquid is typically necessary to form the emulsion.
Stabilized size emulsions can be generally prepared using the procedures taught in colloid
science (e.g. S.E. Friberg & S. Jones, "Emulsions" in the Encyclopedia of Chemical Technology,
Vol, 9 (4th edition)). The general concept consists of imparting energy to a mixture of
hydrophobic material (size in this case) and water in the presence of stabilizer (in this case the
cationic polymers described herein) which results in "small" droplets or particles of the
hydrophobic material suspended in the aqueous phase. The mixing can be accomplished in any
number of ways with the method of mixing being immaterial to the application as long as the
desired results are achieved.
Desired results normally refer to the average particle size and particle size distribution.
Mechanical means for emulsification, for example, can include high-speed agitators, mechanical
homogenizers, or turbine pumps. The latter is frequently employed to prepare size emulsions.
The equipment must be capable of preparing an emulsion particle size in the range generally
between about 0 0 1 and about 10 microns. A preferred particle size is between about 0.5 to 3
microns. The emulsion size here refers to the median diameter of a voi% distribution obtained
with a Malvern Mastersizer laser diffraction instrument (available from Malvern Instruments,
Ltd., Malvern, UK). The median is defined as the diameter where 50% of the particles are
greater than this value and 50% are less than the value. The size of the emulsion can be
controlled by the amount of energy and stabilizer added. Normally, the emulsion would be
prepared from a mixture of the size, the polymeric stabilizer, and enough water to achieve the
desired dilution. As noted in, for example U.S. Patent Nos 4,657,946 and 7,455,751, a
surfactant of the sorts identified therein can be added to enhance the emulsification.
The ratio of ASA size to cationic polymer stabilizer generally range between 1:1 to 20:1,
preferably between about 2:1 to about 15:1 and most preferably this ratio ranges between about
2.5:1 to about 10:1. Ratios are by weight of active ingredients. The size can then be fed to the
paper or paperboard as an emulsion containing a solids content in an aqueous phase ranging from
about 0.1 to about 10 wt% with this solids content containing the ratios of size to cationic
polymer described above. The final size emulsion is normally fed to the wet end of the paper
machine, which can include the thin stock, thick stock, or white water systems Most typicallythe size is fed in the thin stock approach line to the headbox, which also includes the white water
system (e.g., pre-fan pump). Although wet end addition of the size emulsion is the norm, any
addition point that can introduce the size to the final paper sheet would be capable of yielding a
sized sheet and would be used in implementing the method of the invention in various
embodiments. Examples are disclosed in U.S. Patent Nos. 4,657,946 and 7,455,751.
In another embodiment a mixing chamber is used to introduce the sizing emulsion into
the papemiaking process. Examples of such mixing chambers are disclosed in U.S. Patent Serial
No. 11/339,169, "'Method and Arrangement for Feeding Chemicals into a Process Stream,"
(available from Nalco Company in NaperviUe, IL) and the Ultra Turax, model no. UTI-25
(available from IKA® Works Inc. in Wilmington, NC). It is envisioned that any suitable reactor
or mixing device/chamber may be utilized in the method of the invention.
The foregoing may be better understood by reference to the following examples, which
are intended for illustrative purposes and are not intended to limit the scope of the invention.
Example 1
In this example, an embodiment of the invention using 5 mol% DADMAC
(Diallyldimethylanimonium chloride)/AcAm polymer glyoxalated with a 0.8 mole ratio of
glyoxal to AcAm was used as the emulsion stabilizer (Polymer 1) and compared against a 10
mol% DMAEM*MCQ (Dimethylammoniumethylmethyacrylated methylchloride quat)/AcAm
(acrylamide) emulsion stabilizer (Polymer 2). The ASA used in the tests was a commercially
available formulation derived from a mixture of C 16 and C 18 alkenyl chains (available as N7540
from Nalco Company, Naperville, Illinois) at a concentration of 100% (typically ASA is
available neat) was used for the following test method.
Tests were conducted on a dual headbox Fourdrinier paperboard machine producing
about 600 tons/day of linerboard using 100% recycle fiber derived from old corrugated
containers. The test method comprised substituting Polymer 1 in lieu of Polymer 2 as the
emulsion stabilizer for an internal sizing application. The ratio of Polymer 1 to Polymer 2 was
slowly increased, with a ratio of 1: 1 occurring at Reel No. 5 ending with 1:0 at Reel No. 8. At
Reel No. II, the ratio was changed to 0:1 (i.e., a reversion to 100% Polymer 2). The various
ratios of polymers were added to the size turbine on the emulsification skid at the wet end of the
papermachme, where the consistency varied from 0.35-0.90%. The emulsion was fed just after
the pressure screen on the furnish approach to the headbox. Results are shown in Table 1Table 1
Observed from the results in Table 1, was a significant unexpected improvement in sizing
at 100% Polymer 1 (Reel No. 10). In addition, the wet line appeared to go towards the couch
even when sheet at the reel became drier and the fiber orientation by Tensile Stiffness
Orientation ("TSO") was effected enough to cause a need for adjustments to the papermaehine
(e.g., rush to drag, indicating significant increase in drainage rate). Partial Polymer 1 substitution
(Reel No. 5) did not result in any of the observable effects.
Example 2
Tests were conducted on a dual headbox Fourdrinier paperboard machine producing
about 600 tons/day of linerboard using 100% recycle fiber derived from old corrugated
containers. In this example, Polymer 1 and Polymer 2 were used and compared as the emulsion
stabilizer as in example 1. FIG 1 graphically illustrates Reel Moisture and Steam Pressure as a
function of time.
Several unexpected observations were made from the data shown in FIG1. The sheet
moisture at the reel dropped dramatically from 7.6 to 6.1 wt% in a matter of a few minutes after
switching from Polymer 1 to Polymer 2. Sheet moisture drop was then recovered automatically
through steam reductions from 160 to 153 psi. Top ply vacuum seal pit level increases were also
observed, indicating more effective vacuum dewatering, and excess bottom ply white overflow
increases were observed within a few minutes, indicating increased forming section dewatering.
When the test was returned to the Polymer 1 emulsion, a nearly immediate reversion of these
benefits was observed. Moreover, CSF (i.e., pulp freeness) tests did not reveal any noticeable
increase in drainage rate when the sizing emulsion having Polymer 2 was added, indicating this
conventional measurement of drainage did not change.
Example 3
Tests were conducted on a dual headbox Fourdrinier paperboard machine producing
about 600 tons/day of linerboard using 100% recycle fiber derived from old corrugated
containers. It was observed thai use of a 5 mol% DADMAC/AcAm backbone used to prepare
Polymer 2 for ASA emulsification resulted in a loss in sizing, indicating that simple cationiccopolymers without aldehyde-functionalization hurt performance and demonstrating the need for
such functionalization in this application.
Example 4
Tests were conducted on a dual headbox Fourdrinier paperboard machine producing
about 600 tons/day of linerboard using 100% recycle fiber derived from old corrugated
containers. It was observed that addition of Polymer 2 (by itself without being emulsified with
the ASA sizing additive) to the wet end of the papermachine (e.g., thin stock) actually yields less
sizing (as measured by increased Cobb value) demonstrating that the polymer of the invention
must be added as part of the ASA sizing additive to achieve the demonstrated beneficial sizing
results.
Example 5
It is known that emulsions prepared with smaller particle size and narrower distributions
will yield improved sizing (e.g., U.S. Patent No. 4 657,946; J.C. Roberts, "Neutral and Alkaline
Sizing" in Paper Chemistry, J.C. Roberts, Ed., Chapman and Hall: New York, 1991). FIG 2
shows Malvern Mastersizer distributions (vol% of emulsion particles with a given diameter) for
ASA emulsions prepared with an existing polymeric emulsifier containing about 1 wt% of
surfactant (e.g., ethoxylated alkyl phosphate ester) and with the aidehyde-functionalized
polymers of the invention. As indicated in the FIG 2, the median diameter of the emulsion
prepared with glyoxalatsd DADMAC/AcAm (10/90 wt ratio) with 0.8 glyoxal to AcAm ratio
(Polymer 1) is 78% larger than with the best standard emulsifier (consisting of 19.8 wt%
DMAEM*MCQ (dimethylaniinoethylmethacrylate methylchloride quat)/AcAm (acrylamide)
(10/90 mole ratio) + 1 wt% surfactant ethoxylated tridecyl alcohol phosphate ester (Polymer 2)
Additionally, the emulsion size greater than 2 microns diameter is dramatically larger for the
emulsion prepared with the glyoxalated polymer. The size distribution of the glyoxalated
polymer prepared emulsion is also seen to be much broader. FIG 2 also shows that the
glyoxalated polymer produced poorer emulsion as judged by particle size properties
Even though the particle size distribution of the ASA emulsion prepared with glyoxalated
polymer was poorer than the emulsion prepared with standard emulsifier, FIG 3 shows that the
sizing effect on laboratory prepared handsheets as measured by HST method was unexpectedly
better with the glyoxalated polymer emulsion, in contradiction to the accepted belief by those
skilled in the art that a better emulsion yields better sizing. The furnish used in the testing of FIG
3 was recycled board furnish. The HST test evaluates the sizing (water penetration in the sheet)
by optically measuring the time for a dye solution to penetrate the sheet. In the HST testsconducted the dye solution also contained 1 wt% formic acid FIG 3 shows the improved sizing
obtained with the ASA emulsions prepared with the particle size distribution of the ASA
emulsion prepared with glyoxalated polymer even though the emulsion size distribution is poorer
than the comparative emulsion.
All of the compositions and methods disclosed and claimed herein can be made and
executed without undue experimentation in light of the present disclosure. While this invention
may be embodied in many different forms, there are described in detail herein specific preferred
embodiments of the invention. The present disclosure is an exemplification of the principles of
the invention and is not intended to limit the invention to the particular embodiments illustrated.
In addition, unless expressly stated to the contrary, use of the term "a" is intended to include "at
least one" or "one or more." For example, "a device" is intended to include "at least one device"
or "one or more devices."
Any ranges given either in absolute terms or in approximate terms are intended to
encompass both, and any definitions used herein are intended to be clarifying and not limiting.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the
invention are approximations the numerical values set forth in the specific examples are reported
as precisely as possible. Any numerical value, however, inherently contains certain errors
necessarily resulting from the standard deviation found in their respective testing measurements.
Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges
(including all fractional and whole values) subsumed therein.
Furthermore, the invention encompasses any and ail possible combinations of some or ail
of the various embodiments described herein. Any and all patents, patent applications, scientific
papers, and other references cited in this application, as well as any references cited therein, are
hereby incorporated by reference in their entirety. It should also be understood that various
changes and modifications to the presently preferred embodiments described herein will be
apparent to those skilled in the art. Such changes and modifications can be made without
departing from the spirit and scope of the invention and without diminishing its intended
advantages it is therefore intended that such changes and modifications be covered by the
appended claims.

CLAIMS
The claimed invention is:
1. A composition comprising a sizing mixture having a stabilizing amount of one or
more aldehyde-functionalized polymers having at least one aldehyde-reactive monomer species
present in any amount and in any combination in said aidehyde-functionalized polymer, said
monomer species selected from: nonionic monomers; cationic monomers; anionic monomers;
zwitierionic monomers; and any combination of the foregoing; and a sizing amount of a sizing
composition, wherein the one or more aidehyde-functionalized polymers have a weight average
molecular weight of at least about 50,000 g/mole.
2. The composition of Claim 1, wherein the one or more aidehyde-functionalized
polymers is stably present in an amount from about 2 wt% to about 33 wt%, based on total
weight of the composition
3. The composition of Claim 1, wherein the one or more aldehyde-functionaiized
polymers is fonned from one or more precursor polymers having aldehyde-reactive moieties
selected from the group consisting of: amines, amides, hydroxyls, and any combination of the
foregoing.
4. The composition of Claim 1 wherein the one or more aldehyde-functionaiized
polymers comprise a copolymer fonned from diallydimethylammonium chloride monomers and
acrylamide monomers in a weight-to-weight ratio of about 10/90, respectively.
5. The composition of Claim 1, wherein the one or more aldehyde-functionaiized
polymers is formed by reacting one or more precursor polymers having aldehyde-reactive
moieties with one or more types of mono-functional and/or poly-functional aldehydes in a molar
ratio of about 0.05 to about 1.5, respectively.
6. The composition of Claim 1, wherein the one or more aldehyde-functionaiized
polymers are formed from by reacting a preformed polymer having one or more aldehyde-
reactive moieties with one or more aldehydes selected from the group consisting of:
formaldehyde, paraformaldehyde, glyoxal, glutaraldehyde, and combinations thereof.
7. The composition of Claim 1, wherein the aldehyde-functionaiized polymers have a
weight average molecular weight of at least about 300,000 g/mole.
8. The composition of Claim 1, wherein the sizing composition comprises rosin sizes,
alkylene ketene dimmers, alkenyl succinic anhydrides, and combinations thereof.9. The composition of Claim 1, further comprising a solids content ranging from about
0 1 to about 10 wt% in an aqueous phase.
10. A method of improving paper and paperboard production and enhancing sizing, the
method comprising adding an effective amount of the composition of Claim 1 to the paper
machine.
11. The method of Claim 10, further comprising adding said composition to (i) wet end
locations used for conventional wet end additives and/or (ii) into white water systems.
12. The method of Claim 10, further comprising adding said composition to a thin stock
in the papermaking process and/or adding said composition to a thick stock in the papermaking
process.
13. A method of producing a medium having ceilulosic fibers, comprising adding the
composition of Claim 1 to the medium at any point in a papermaking process, the medium
optionally having mineral f i ller(s)
14. The method of Claim 13, wherein the composition is added at a point selected from
the group consisting of: wet end, including thin stock and/or thick stock; directly to the paper
sheet; and any combination of the foregoing.
15. The method of Claim 13, further comprising wherein said composition has a ratio
from about 1:1 to about 20:1 of the sizing composition to the one or more aldehyde-
iunctionalized polymers, respectively.