Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/06—Paper forming aids
  • D21H21/10—Retention agents or drainage improvers
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
  • D21H17/29—Starch cationic
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
  • D21H17/375—Poly(meth)acrylamide
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
  • D21H17/45—Nitrogen-containing groups
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/66—Salts, e.g. alums

Definitions

• This invention relates generally to the field of papermaking and, more particularly, to an improved papermaking process utilizing hydrophilic dispersion copolymers of diallyl-N,N-disubstituted ammonium halide and (meth)acrylamide as retention and drainage aids.
• an aqueous cellulosic suspension or slurry is formed into a paper sheet.
• the cellulosic slurry is generally diluted to a consistency (percent dry weight of solids in the slurry) of less than 1 percent, and often below 0.5 percent, ahead of the paper machine, while the finished sheet must have less than 6 weight percent water.
• a consistency percent dry weight of solids in the slurry
• the least costly dewatering method is drainage, and thereafter more expensive methods are used, including vacuum pressing, felt blanket blotting and pressing, evaporation and the like, and any combination of such methods. Because drainage is both the first dewatering method employed and the least expensive, improvements in the efficiency of drainage will decrease the amount of water required to be removed by other methods and improve the overall efficiency of dewatering, thereby reducing the cost thereof.
• a papermaking furnish contains particles that range in size from about the 2 to 3 millimeter size of cellulosic fibers to fillers measuring only a few microns. Within this range are cellulosic fines, mineral fillers (employed to increase opacity, brightness and other paper characteristics) and other small particles that generally, without the inclusion of one or more retention aids, would pass through the spaces (pores) between the cellulosic fibers in the fiber mat being formed.
• a coagulant/flocculant system which is added ahead of the paper machine.
• a coagulant such as a low molecular weight cationic synthetic polymer or a cationic starch is first added to the furnish.
• the coagulant generally reduces the negative surface charges present on the particles in the furnish, particularly cellulosic fines and mineral fillers, and thereby agglomerates such particles.
• the coagulant is followed by the addition of a flocculant.
• the flocculant is generally a high molecular weight cationic or anionic synthetic polymer which bridges the particles and/or the agglomerates from one surface to another, thereby binding the particles into large agglomerates.
• the presence of such large agglomerates in the furnish increases retention.
• the agglomerates are filtered out of the water onto the fiber web, where unagglomerated particles would otherwise generally pass.
• a flocculated agglomerate generally does not interfere with the drainage of the fiber mat to the extent that would occur if the furnish were gelled or contained gelatinous material, when such flocs are filtered by the fiber web the pores thereof are reduced, thus reducing drainage efficiency. Hence, the retention is increased at the expense of a decrease in drainage.
• Another system uses the combination of cationic starch followed by colloidal silica to increase the amount of material retained on the web by charge neutralization and adsorption of smaller agglomerates.
• U.S. Patent No. 5,266,164 discloses a method for improving the retention of mineral fillers and cellulose fibres on a cellulosic fibre sheet, which method includes adding a high molecular weight cationic flocculant, prepared in water-in-oil emulsion form from acrylamide and DADMAC (diallyldimethyl ammonium chloride), to the cellulose pulp slurry and after a shearing step adding a high molecular weight water soluble anionic flocculant.
• a high molecular weight cationic flocculant prepared in water-in-oil emulsion form from acrylamide and DADMAC (diallyldimethyl ammonium chloride)
• Canadian Patent No. 2,102,742 relates to improvements in the production of newsprint by improving the retention of colloidal particles, particularly fine and filler retention, using intermediate molecular weight (50 000-1 500 000) DADMAC acrylamide copolymers as the treating agent.
• European Patent No. 0 760 406 is directed to a method for minimising pitch, ink and stickies particle deposits in the papermaking process by adding a water soluble DADMAC-acrylamide copolymer to a fiber suspension, and further adding bentonite, thereby increasing retention of pitch, ink and stickies onto the fibre and minimising deposition on the paper machine and associated parts.
• U.S. Patent No. 5,587,415 discloses a water soluble cationic (co)polymer dispersion prepared by the polymerisation of a cationic quaternary monomer obtained by quaternisation of an alkyl halide, the polymerisation being carried out in a salt solution which does not dissolve the (co)polymer, and in the presence of a cationic polymer dispersant which is soluble in the salt solution.
• latex is defined to mean an inverse water-in-oil emulsion polymer.
• dispersion polymers which do not require an inverter system and can be introduced to the papermaking process using simple feeding equipment.
• the method of the invention calls for forming an aqueous cellulosic papermaking slurry, adding from 0.02-2.3 kg of a hydrophilic dispersion polymer per 907kg of slurry solids to the slurry, wherein the hydrophilic dispersion polymer has a cationic charge of from 1 mole percent to 50 mole percent and an intrinsic viscosity of from 0.5 to 10 dl/gram, draining the slurry to form a sheet and drying the sheet.
• the hydrophilic dispersion polymer comprises:
• hydrophilic dispersion polymers utilized in the present invention do not require an inverter system and can be introduced to the papermaking process using simple feeding equipment.
• the present invention is directed to a method for improving retention and drainage performance in a papermaking process which comprises forming an aqueous cellulosic papermaking slurry, adding a hydrophilic dispersion polymer to the slurry, draining the slurry to form a sheet and then drying the sheet.
• the hydrophilic dispersion polymer of the invention is a copolymer of diallyl-N,N-disubstituted ammonium halide cationic monomer and (meth)acrytamide.
• a preferred copolymer is formed from diallyldimethyl ammonium chloride (DADMAC) and acrylamide (AcAm).
• DMDMAC diallyldimethyl ammonium chloride
• AcAm acrylamide
• the hydrophilic dispersion polymers of the invention show improved or equal activity with respect to retention and drainage performance without the unwanted addition of oils and surfactants as compared to conventional cationic latex polymers. Additionally, these polymers require no inverter system and can be introduced to the papermaking process using simple feeding equipment.
• dispersion polymers Another advantage concerns the mode of addition of the dispersion polymers.
• conventional water-soluble polymers are now commercially available in a powder form. Prior to use, the polymeric powder must be dissolved in an aqueous medium for actual application. The polymer swells in aqueous medium, and the dispersed particles flocculate. It is typically very difficult to dissolve the conventional polymers in an aqueous medium.
• the dispersion polymers of this invention by their nature, avoid dissolution-related problems.
• dispersion copolymers formed from DADMAC and AcAm have the advantageous flexibility in that they may be used either as the sole polymeric treatment, or as a component in a conventional dual polymer program which requires both a conventional coagulant and a flocculant.
• the dispersion copolymers of the present invention if required in the form of an aqueous solution resulting from dilution with water, can be advantageously used in a number of technological fields as flocculating agents, thickeners, soil conditioners, adhesives, food additives, dispersants, detergents, additives for medicines or cosmetics, among others.
• Example 1 outlines the process for preparing the copolymer at various ratios of the monomer components in the range of from about 1:99 to about 99:1 of acrylamide type monomer to diallyl-N,N-disubstituted ammonium halide.
• the di-substitutents of the monomer may be C 1 - C 20 alkyl groups, aryl groups, alkylaryl groups or arylalkyl groups.
• each of the di-substituents can be a different group.
• one intended halide is N-methyl-N-ethyl-N,N-diallyl ammonium chloride.
• DADMAC A specific example of one applicable halide is DADMAC.
• the amount of DADMAC present in the copolymer is from about 5 mole percent to about 30 mole percent.
• Diallyl-N,N-disubstituted ammonium halides, especially DADMAC are well-known and commercially available from a variety of sources.
• the counterion may also be bromide, sulfate, phosphate, monohydrogen phosphate and nitrate, among others.
• One method for the preparation of DADMAC is detailed in U. S. Patent No. 4,151,202.
• substituted (meth)acrylamide monomers may have either straight chain or branched alkyl groups.
• Applicable monomers include, but are not limited to, ethyl hexyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, dimethylaminohydroxypropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, C 1 -C 10 N-alkyl acrylamide, C 1 -C 10 N-alkyl methacrylamide, N-aryl acrylamide, N-aryl methacrylamide, N-arylalkyl acrylamide, N-isopropyl (meth)acrylamide, N,N-dimethylacrylamide (meth)acrylamide, C 1 - C 10 N,N-dialkyl acrylamide, C 1 - C 10 N, N-dialkyl methacrylamide, N,N-d
• a polyvalent anionic salt is incorporated in an aqueous solution.
• the polyvalent anionic salt is suitably a sulfate, a phosphate or a mixture thereof.
• Preferable salts include ammonium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, ammonium hydrogen phosphate, sodium hydrogen phosphate and potassium hydrogen phosphate.
• these salts may be each used as an aqueous solution thereof having a concentration of 15% or above.
• a dispersant polymer is present in the aqueous anionic salt solution in which the polymerization of the above monomers occurs.
• the dispersant polymer is a water-soluble high molecular weight cationic polymer and is preferably soluble in the above-mentioned aqueous salt solution. It is preferred that the dispersant polymer be used in an amount of from about 1 to 10% by weight based on the total weight of the hydrophilic dispersion polymer.
• the dispersant polymer is composed of 20 mole % or more of cationic monomer units of diallyl disubstituted ammonium halide or N,N-dialkylaminoethyl(meth)acrylates and their quaternary salts.
• the residual mole % is AcAm or (meth)AcAm.
• the performance of the dispersant is not greatly affected by molecular weight.
• the molecular weight of the dispersant is preferably in the range of about 10,000 to 10,000,000.
• Preferred dispersants include homopolymers of diallyldimethyl ammonium chloride, dimethylaminoethylacrylate methyl chloride quaternary salt and dimethyl-aminoethylmethacrylate methyl chloride quaternary salt.
• a multifunctional alcohol such as glycerin or polyethylene glycol is coexistent in the polymerization system.
• the deposition of the fine particles is smoothly carried out in the presence of these alcohols.
• polysaccharides such as starch, dextran, carbomethoxy cellulose and pullulan, among others, can also be used as stabilizers either solely, or in conjunction with other organic cationic flocculants.
• a usual water-soluble radical-forming agent can be employed, but preferably water-soluble azo compounds such as 2,2'-azobis(2-amidinopropane) hydrochloride and 2,2'-azobis(N,N'-dimethyleneisobutylamine) hydrochloride are used.
• a seed polymer is added before the beginning of the polymerization of the above monomers for the purpose of obtaining a fine dispersion.
• the seed polymer is a water-soluble cationic polymer insoluble in the aqueous solution of the polyvalent anion salt.
• the seed polymer is preferably a polymer prepared from the above monomer mixture by the process described herein. Nevertheless, the monomer composition of the seed polymer need not always be equal to that of the water-soluble cationic polymer formed during polymerization. However, like the water-soluble polymer formed during polymerization, the seed polymer should contain at least 5 mole percent of cationic monomer units of diallyldimethyl ammonium halide.
• the seed polymer used in one polymerization reaction is the water-soluble polymer prepared in a previous reaction which used the same monomer mixture.
• aqueous cellulosic slurry is first formed by any conventional means generally known to those skilled in the art.
• a hydrophilic dispersion polymer is next added to the slurry.
• the hydrophilic dispersion polymer is formed by the polymerization of
• the cellulosic papermaking slurry is next drained to form a sheet and then dried.
• the steps of draining and drying may be carried out in any conventional manner generally known to those skilled in the art.
• the cationic monomer may be DADMAC and the second monomer may be AcAm.
• the hydrophilic dispersion polymer has a cationic charge of from 1 mol % to 50 mol %.
• conventional coagulants conventional flocculants, alum, cationic starch or a combination thereof may also be utilized as adjuncts with the dispersion polymers, though it must be emphasized that the dispersion polymer does not require any adjunct for effective retention and drainage activity.
• the range of intrinsic viscosities for the hydrophilic dispersion polymers of the invention is from 0.5 to 10 dl/g, preferably from 1.5 to 8.5 dl/g and most preferably from 2.5 to 7.5 dl/g.
• the dose is from 0.02 to 2.3 kg (0.05 to 5.0 pounds) of active per 907kg (ton) of slurry solids
• the mixture was heated to 48°C and 2.50 grams of a 4% solution of 2,2'-azobis(2-amidinopropane) dihydrochloride and 2.50 grams of a 4% solution of 2,2'-azobis(N,N'-dimethylene isobutryramidine) dihydrochloride were added.
• the resulting solution was sparged with 1000 cc/min of nitrogen. After 15 minutes, polymerization began and the solution became viscous. Over the next 4 hours, the temperature was maintained at 50°C and a solution containing 178.42 grams of 49.0% AcAm (1.230 moles) and 0.2 grams of EDTA was pumped into the reactor using a syringe pump.
• the resulting polymer dispersion had a Brookfield viscosity of 4200 cps.
• the dispersion was then further reacted for 2.5 hours at a temperature of 55°C.
• the resulting polymer dispersion had a Brookfield viscosity of 3300 cps. 10 grams of 99% adipic acid, 10 grams of ammonium sulfate and 12.5 grams of a 60% aqueous solution of ammonium thiosulfate were added to the polymer dispersion.
• the resulting dispersion had a Brookfield viscosity of 1312.5 cps and contained 20% of a 50 weight percent copolymer of DADMAC and AcAm with an intrinsic viscosity of 6.32 dl/gm in 1.0 molar NaNO 3 .
• VDT vacuum drainage tester
• the furnish was treated in a Britt jar stirring at 1000 rpm.
• the VDT tests were conducted by the normal procedure of transferring the treated furnish to the VDT chamber, and then filtering under 54 x 10 3 Pa (15 in. Hg (7.84 psi)) vacuum through the Filpaco #716 paper.
• the testing conditions are given in Table II.
• the drainage rates are expressed in terms of the time taken to collect 100 ml filtrate volumes.
• Cationic polymer programs showed activity with the base sheet furnish relative to an untreated sample (Blank).
• Table III shows the VDT drainage data for polymers listed in Table I. A lower drainage time (for a constant volume of 100 ml) indicates a higher drainage rate. Therefore, the higher the drainage rate, the more effective the treatment.
• the results in Table III demonstrate that the hydrophilic DADMAC/AcAm dispersion polymer ( Dispersion I) is superior to conventional treatments. Moreover, the drainage performance of Dispersion I was better than its latex analog, Polymer I. In addition, the turbidity of the filtrate obtained with Dispersion I was visibly clearer than the other polymers tested, implying better retention.
• a series of VDT drainage experiments were performed using the hydrophilic dispersion DADMAC/AcAm polymer (Dispersion I) with thin stock obtained from a Midwestern boxboard papermill.
• the furnish was treated in a Britt jar stirring at 1000 rpm.
• the VDT tests were conducted by the normal procedure of transferring the treated furnish to the VDT chamber, and then filtering under 54 x 10 3 Pa (15 in. Hg (7.84 psi)) vacuum through the Filpaco #716 paper.
• the testing conditions are shown in Table IV.
• the results are summarized in Table V.
• the drainage rates are expressed in terms of the time taken to collect 400 ml filtrate volumes. A lower drainage time to collect a constant volume of 400 ml indicates better performance.
• the data in Table V show the flexibility of the hydrophilic dispersion polymer in that it can be used either as a sole polymeric treatment (flocculant) or as a coagulant in a dual program with conventional flocculants (Polymer Q, Polymer N).

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Applications Claiming Priority (1)

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• 1999
  • 1999-01-15 BR BRPI9908576-3A patent/BR9908576B1/pt not_active IP Right Cessation
  • 1999-01-15 KR KR1020007007909A patent/KR100572306B1/ko not_active IP Right Cessation
  • 1999-01-15 DE DE69924371T patent/DE69924371T2/de not_active Expired - Lifetime
  • 1999-01-15 EP EP99903105A patent/EP1082493B1/en not_active Expired - Lifetime
  • 1999-01-15 CN CNB998024716A patent/CN1189623C/zh not_active Expired - Lifetime
  • 1999-01-15 AU AU23208/99A patent/AU766846B2/en not_active Expired
  • 1999-01-15 WO PCT/US1999/000869 patent/WO2000042253A1/en active IP Right Grant
  • 1999-01-15 DK DK99903105T patent/DK1082493T3/da active
• 2000
  • 2000-07-18 NO NO20003678A patent/NO326100B1/no not_active IP Right Cessation

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