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
  • D21H17/33—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
• • 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
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
• • 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

Definitions

• the present invention relates to using hydrophobically modified water-soluble polymers, also referred to hereinafter as hydrophobically associative polymers or HAPs, in the preparation of cellulosic fiber compositions.
• HAPs hydrophobically associative polymers
• the present invention further relates to cellulosic fiber compositions, such as paper and paperboard, which incorporate the HAPs
• drainage/dewatering improvement drainage or dewatering of the fibrous slurry on the papermaking wire or fabric is often the limiting step in achieving faster method speeds. Improved dewatering can also result in a dryer sheet in the press and dryer sections, resulting in reduced steam consumption. Yet further, this is the stage in the papermaking method that determines many sheet final properties.
• papermaking retention aids are used to increase the retention of fine furnish solids in the web during the turbulent method of draining and forming the paper web. Without adequate retention of the fine solids, they are either lost to the method effluent or accumulate to high levels in the recirculating white water loop, potentially causing deposit buildup and impairing paper machine drainage. Additionally, insufficient retention of the fine solids increases the papermakers' cost due to loss of additives intended to be adsorbed on the fiber to provide the respective paper opacity, strength, or sizing property.
• High MW water-soluble polymers with either cationic or anionic charge have traditionally been used as retention and drainage aids.
• U.S. Pat. Nos. 4,294,885 and 4,388,150 teach the use of starch polymers with colloidal silica.
• U.S. Pat. No. 4,753,710 teaches flocculating the pulp furnish with a high MW cationic flocculant, inducing shear to the flocculated furnish, and then introducing bentonite clay to the furnish.
• U.S. Pat. Nos. 5,274,055 and 5,167,766 disclose using chemically crosslinked organic microparticle or micropolymers as retention and drainage aids in papermaking process.
• Hydropohobically modified water-soluble polymers also referred to hereinafter as hydrophobically associative polymers or HAPs
• HAPs hydrophobically associative polymers
• U.S. Pat. Nos. 4,432,881 and 4,861,499 disclose the use of these polymers as thickening agents for paint formulations and for applications in oil recovery methods, such as drilling mud formulations, fracturing fluids, liquid mobility control agents, friction reducing agents, hydraulic fluids, and lubricants.
• These patents do not teach or suggest the use of the polymers in cellulosic compositions such as paper, or in methods for preparing these cellulosic compositions.
• U.S. Pat. No. 4,305,860 discloses the preparation of stable, pumpable, solvent-free polyampholyte lattices (colloidal dispersions of a solid copolymer in water) characterized by their colloidal nature and their high solids content and low bulk viscosity.
• the lattices are prepared by polymerizing about 10 to 30 mole % of at least one cationic monomer, 5 to 30 mole % of at least one anionic monomer, 15 to 35 mole % of at least one hydrophobic monomer and 5 to 70 mole % of at least one non-ionic hydrophilic monomer, with the monomer percentages totaling 100 mole %, in the presence of water and a free-radical initiator and optionally a chelating agent.
• the lattices are taught to be particularly useful as pigment retention and drainage aids in the manufacture of paper and may be added to the pulp while the latter is in the headbox, beater, hydropulper or stock chest.
• the high hydrophobic group content (>15 mole %) makes this disclosed polymer insoluble in aqueous solution, which distinguishes itself from the water-soluble HAP polymers disclosed in the present invention.
• EP 0 896 966 A1 discloses the preparation of associative polymers by inverse emulsion procedures utilizing a pendant acrylate hydrophobe chain extended with a polyoxyethylene group.
• the associative acrylic polymers comprise from 95 to 99.95% moles of at least one monomer selected from neutral ethylene, anionic or cationic monomers, from 0.05 to 5% moles of at least one acrylic monomer containing the radical 2,4,6-triphenoethyl benzene, and from 0 to 0.2% moles of at least one polyunsaturated monomer. It is preferred that the associative polymers contain from 0.5 to 5 molar % of polyoxyethylene 2,4,6-triphenoethyl benzene methacrylate.
• the polymers may be used in diverse areas, such as paints, glues and adhesives, construction, textiles and paper.
• the composition is claimed for use as a thickener, flocculation agent, and/or charge retention agent; no data or further specification is provided for the utilization.
• the present invention is directed to a cellulosic fiber composition, particularly a cellulosic sheet such as paper or paperboard.
• the invention is also directed to a method for making the composition.
• the present invention relates to a method of making a cellulosic fiber composition that includes adding, to a cellulosic pulp slurry, a HAP and relates to a cellulosic fiber composition including an aqueous slurry of cellulosic pulp and a HAP.
• the HAP is preferably a copolymer including hydrophobic groups that are capable of forming a physical network structure through hydrophobic association, and has at least one monomer selected from the group consisting of nonionic ethylenically unsaturated monomers, cationic ethylenically unsaturated monomers, or anionic ethylenically unsaturated monomers.
• the HAP is highly associative and forms a network structure in aqueous solution as demonstrated by a tan ⁇ value less than an analogous polymer without the hydrophobic modification, as determined by viscoelastic characterizations of a 0.5% solution.
• a significent improvement in retention and drainage activity is obtained when HAP is applied to a pulp furnish, and at the same time a satisfactory sheet formation is maintained, which is the unique property that a traditional flocculant could not achieve.
• the HAP is usually water soluble.
• the HAP may include at least one hydrophobic ethylenically unsaturated monomer present in an amount from about 0.001 mole percent to about 10 mole percent, and at least one monomer selected from a nonionic ethylenically unsaturated monomer, a cationic ethylenically unsaturated monomer, or an anionic ethylenically unsaturated monomer with the proviso that the at least one hydrophobic ethylenically unsaturated monomer does not contain 2,4,6-triphenoethyl benzene.
• the at least one hydrophobic ethylenically unsaturated monomer may be an ethylenically unsaturated monomer having at least one pendant hydrophobic group of the general structure:
• R 1 is hydrogen or methyl
• R 2 when present, is —CH 2 —, —C(O)—O—, —O—C(O)—, —C(O)—NR 6 —, —NR 6 —C(O)—, or —O—
• R 3 when present, is —(—CH 2 —CHR 1 —O—) n —, C 1 -C 20 alkyl, or C 1 -C 20 hydroxy alkyl wherein n equals 1 to 40 and R 1 is as decribed above
• R 4 when present, is —NR 6 — or —N + (R 6 ) 2 —
• R 5 is the pendant hydrophobic group selected from one or more of C 4 -C 20 alkyls, C 4 -C 20 cycloalkyls, polynuclear aromatic hydrocarbon groups, alkaryls wherein alkyl has one or more carbons, or haloalkyls of four or more
• the polynuclear aromatic hydrocarbon group may be naphthyl.
• the haloalkyls of four or more carbons may be perfluoroalkyls which preferably are selected from one or more of C 4 F 9 -C 20 F 41 .
• the pendant hydrophobic group may be polyalkyleneoxy groups wherein the alkylene is propylene or higher alkylene and there is at least one alkyleneoxy unit per hydrophobic moiety or may be selected from one or more of C 4 -C 20 alkyl groups or preferably from one or more of C 8 -C 20 alkyl groups.
• the hydrophobic ethylenically unsaturated monomer depicted in FIG. 1 may be selected from one or more hydrocarbon esters of ethylenically unsaturated carboxylic acids and their salts, N-alkyl ethylenically unsaturated amides, ⁇ -olefins, vinyl esters, vinyl ethers, N-vinyl amides, alkylstyrenes, alkyl polyethyleneglycol (meth)acrylates, or N-alkyl ethylenically unsaturated cationic monomers.
• hydrocarbon esters of ethylenically unsaturated carboxylic acids and their salts N-alkyl ethylenically unsaturated amides, ⁇ -olefins, vinyl esters, vinyl ethers, N-vinyl amides, alkylstyrenes, alkyl polyethyleneglycol (meth)acrylates, or N-alkyl ethylenically
• the ethylenically unsaturated carboxylic acids may preferably be selected from the C 10 -C 20 alkyl esters of acrylic and methacrylic acid and more preferably from dodecyl acrylate or dodecyl methacrylate.
• the ethylenically unsaturated amides may preferably be selected from N-octadecyl acrylamide, N-octadecyl methacrylamide, or N,N-dioctyl acrylamide.
• the ⁇ -olefins may preferably be selected from 1-octene, 1-decene, 1-dodecene, or 1-hexadecene.
• the vinyl esters may preferably be vinyl laurate or vinyl stearate.
• the vinyl alkyl ethers may preferably be dodecyl vinyl ether or hexadecyl vinyl ether.
• the N-vinyl amides may preferably be N-vinyl lauramide or N-vinyl stearamide.
• the alkylstyrene may preferably be t-butyl styrene.
• the alkyl polyethyleneglycol (meth)acrylates may preferably be selected from laurylpolyethoxy(23) methacrylate.
• the N-alkyl ethylenically unsaturated cationic monomers may preferably be selected from the C 10 -C 20 alkyl halide quaternary salts of methyldiallyamine, N,N-dimethylaminoalkyl(meth)acrylates, and N,N-dialkylaminoalkyl(meth)acrylamides.
• the at least one nonionic ethylenically unsaturated monomer may be one or more of acrylamide, methacrylamide, N-alkylacrylamides, N,N-dialkylacrylamides, methyl acrylate, methyl methacrylate, acrylonitrile, N-vinyl methylacetamide, N-vinyl methyl formamide, vinyl acetate, or N-vinyl pyrrolidone.
• the N-alkylacrylamide is preferably N-methylacrylamide and the N,N-dialkylacrylamide is preferably N,N-dimethylacrylamide.
• the at least one nonionic ethylenically unsaturated monomer is preferably one or more of acrylamide, methacrylamide, or N-methylacrylamide and more preferably acrylamide.
• the at least one anionic ethylenically unsaturated monomer may be one or more of acrylic acid, methacrylic acid, 2-acrylamido-2-methyl-propane sulfonate, sulfoethyl-(meth)acrylate, vinylsulfonic acid, styrene sulfonic acid, maleic acid or the salts thereof, preferably one or more of acrylic acid, methacrylic acid or the salts thereof and more preferably one or more of the sodium or ammonium salts of acrylic acid.
• the at least one cationic ethylenically unsaturated monomer may be selected from one or more of diallylamine, the (meth)acrylates of dialkylaminoalkyl compounds, the (meth)acrylamides of dialkylaminoalkyl compounds, the N-vinylamine hydrolyzate of N-vinylformamide, and the salts and quaternaries thereof.
• the quaternary salt of diallylamine may preferably be diallyldimethylammonium chloride.
• the dialkylaminoalkyl (meth)acrylamide may preferably be N,N-dimethylaminopropylacrylamide, the acid or quantenary salt thereof may preferably be N,N,N-trimethylaminopropylacrylamide chloride.
• the dialkylaminoalkyl (meth)acrylate may preferably be N,N-dimethylaminoethylacrylate, the acid or quantenary salt thereof may preferably be N,N,N-trimethylaminoethylacrylate chloride.
• the at least one cationic ethylenically unsaturated monomer may also be selected from one or more of the compounds of the following general formulae:
• R 1 is hydrogen or methyl
• R 2 , R 3 , and R 4 are hydrogen, alkyl of C 1 to C 3 , or hydroxyethyl,
• R 2 and R 3 or R 2 and R 4 can combined to form a cyclic ring containing one of more hetero atoms
• Z is the conjugate base of an acid
• X is oxygen or NR 1 wherein R 1 is as defined above, and
• A is an alkylene group of C 1 to C 12 ;
• R 5 and R 6 are hydrogen or methyl
• R 7 and R 8 are hydrogen, alkyl of C 1 to C 3 , or hydroxyethyl
• N-vinylformamides and the associated hydrolyzates as represented by recurring units of
• R 1 , R 2 and R 3 are each H or C 1 to C 3 alkyl
• hydrophobic ethylenically unsaturated monomer encompasses the cationic ethylenically unsaturated monomers depicted in FIGS. 2-6 wherein, for example, the definition of R 2 of FIGS. 2, 4-5 and R 7 of FIG. 3 are substituted with pendant hydrophobic moeity R 5 of FIG. 1.
• HAP in accordance with this invention (an 0.5% aqueous solution of the HAP) have a dynamic oscillation frequency sweep tan delta value at 0.0068 Hz less than an analogous polymer absent the hydrophobic ethylenically unsaturated monomer, most preferably less than 1. It is also preferable that the at least one hydrophobic ethylenically unsaturated monomer groups be present in an amount from about 0.01 mole percent to about 10 mole percent, and more preferably in an amount from about 0.1 mole percent to about 5.0 mole percent.
• the HAP used in this invention may be an anionic, nonionic, cationic or amphoteric copolymer, and preferably an anionic copolymer.
• the anionic copolymer may include at least one hydrophobic ethylenically unsaturated monomer and at least one anionic ethylenically unsaturated monomer and may further include at least one nonionic ethylenically unsaturated monomer.
• the anionic copolymer may include about 0.001 mole percent to about 10 mole percent of the at least one hydrophobic ethylenically unsaturated monomer, about 1 mole percent to about 99.999 mole percent of the at least one anionic ethylenically unsaturated monomer, and about 1 mole percent to about 99.999 mole percent of the at least one nonionic ethylenically unsaturated monomer; preferably about 0.01 mole percent to about 5 mole percent of the at least one hydrophobic ethylenically unsaturated monomer, about 10 mole percent to about 90 mole percent of the at least one anionic ethylenically unsaturated monomer, and about 10 mole percent to about 90 mole percent of the at least one nonionic ethylenically unsaturated monomer; and more preferably about 0.1 mole percent to about 2.0 mole percent of the at least one hydrophobic ethylenically unsaturated monomer, about 30 mole
• inventive cellulosic pulp slurry containing the HAP may also include, at the option of the skilled worker, other components such as at least one flocculant, at least one starch, at least one inorganic or organic coagulant, or at least one filler.
• the present invention also includes a cellulosic sheet produced by the inventive method.
• the cellulosic sheet may include paper and paperboard incorporating the HAP.
• the present invention also relates to a method of making a cellulosic fiber composition which includes adding, to a cellulosic pulp slurry, a HAP and relates to a cellulosic fiber composition including an aqueous slurry of cellulosic pulp and a HAP, where the HAP includes at least one hydrophobic ethylenically unsaturated monomer present in an amount from about 0.001 mole percent to about 10 mole percent and selected from one or more of C 10 -C 20 alkyl esters of acrylic and methacrylic acid; and at least one monomer selected from: a) about 1 mole percent to about 99.999 mole percent of at least one nonionic ethylenically unsaturated monomer selected from one or more of acrylamide, methacrylamide, N-alkylacrylamides, N,N-dialkylacrylamides, methyl acrylate, methyl methacrylate, acrylonitrile, N-vinyl methylace
• the HAP may preferably include at least one hydrophobic ethylenically unsaturated monomer present in an amount from about 0.001 mole percent to about 10 mole percent and selected from one or more of C 10 -C 20 alkyl esters of acrylic and methacrylic acid; and at least one monomer selected from: a) about 1 mole percent to about 99.999 mole percent of at least one nonionic ethylenically unsaturated monomer selected from one or more of acrylamide, methacrylamide, or N-alkylacrylamides; b) about 1 mole percent to about 99.999 mole percent of at least one anionic ethylenically unsaturated monomer selected from one or more of acrylic acid, methacrylic acid or the salts thereof; or c) about 1 mole percent to about 99.999 mole percent of at least one cationic ethylenically unsaturated monomer selected from one or more of N,N-dialkylaminoalkyl acrylates,
• the present invention also relates to a method of making a cellulosic fiber composition which includes adding, to a cellulosic pulp slurry, an anionic HAP and relates to a cellulosic fiber composition including an aqueous slurry of cellulosic pulp and an anionic HAP, where the anionic HAP preferably includes at least one hydrophobic ethylenically unsaturated monomer selected from one or more of lauryl acrylate or lauryl methacrylate, the at least one nonionic ethylenically unsaturated monomer being acrylamide, and the at least one anionic ethylenically unsaturated monomer being acrylic acid.
• the invention also relates to a cellulosic sheet produced by the aforesaid method and from the aforesaid composition.
• the cellulosic sheet may include paper and paperboard incorporating the HAP.
• the cellulosic fiber composition of the invention preferably comprises the HAP and its viscoelasticity properties, as discussed.
• Preferred cellulosic fiber compositions of the invention include paper.
• HAP refers to the hydrophobically associative polymer of this invention.
• hydrocarbon includes “aliphatic”, “cycloaliphatic”, and “aromatic”.
• aliphatic and cycloaliphatic are understood as including “alkyl”, “alkenyl”, “alkynyl”, and “cycloalkyl”.
• aromatic also unless stated otherwise—is understood as including “aryl”, “aralkyl”, and “alkaryl”.
• Hydrocarbon groups are understood as including both nonsubstituted hydrocarbon groups and substituted hydrocarbon groups, with the latter referring to the hydrocarbon portion bearing additional substituents besides the carbon and hydrogen.
• aliphatic, cycloaliphatic, and aromatic groups are understood as including both nonsubstituted aliphatic, cycloaliphatic, and aromatic groups and substituted aliphatic, cycloaliphatic, and aromatic groups, with the latter referring to the aliphatic, cycloaliphatic, and aromatic portion bearing additional substituents besides the carbon and hydrogen.
• copolymers are understood as including polymers consisting of, or consisting substantially of or consisting essentially of, two different monomeric units. Copolymers are further understood as including polymers incorporating three or more different monomeric units, e.g., terpolymers, etc.
• the invention comprises a method of making cellulosic fiber compositions—particularly cellulosic fiber webs, more particularly cellulosic fiber sheets, and still more particularly paper and paperboard.
• This method comprises the addition of at least one HAP to a suitable paper furnish—e.g., a cellulosic fiber pulp or stock, particularly a cellulosic wood fiber pulp or stock.
• this polymer is added to a slurry comprising an aqueous suspension of the furnish.
• a cellulosic web particularly a sheet, and still more particularly paper or paperboard—is formed from the slurry.
• the method of the invention can entail the steps of providing a paper furnish comprised of cellulosic fibers with or without additional mineral fillers suspended in water, depositing the furnish on a papermaking wire or fabric, and forming a sheet out of the solid components by dewatering the slurry, with the at least one HAP being added at one or more points during this method.
• this polymer is introduced into the fibrous slurry prior to the dewatering sequence.
• the HAP serves to provide an increase in retention of fine particles and/or an increase in fibrous dewatering.
• This polymer is particularly effective in providing for retention both of filler—where it is employed—and of cellulosic fiber fines, these fines being generated from the fiber during the method of the invention. It is postulated that HAPs form physical network structure through the hydrophobic group in aqueous solution as demonstrated by their viscoelasticity behavior. Since the three-dimension structure of the HAP is less absorbed on the particle surface, better bridging is provided between particles, which leads to better retention and drainage activity.
• Viscoelastic behavior as discussed herein denotes a time dependent response to a deformation, i.e., at short times the material is hard and glassy, whereas at longer times the material is rubbery or viscous.
• a common way to measure this phenomenon is by stress relaxation, where an instantaneous strain is imposed upon a material, and the resultant stress decay over time is recorded.
• a purely viscous material would exhibit a stress of zero once the strain becomes constant, while an elastic solid would show no stress decay.
• a viscoelastic material would exhibit a stress decay between these two extremes; thus exhibiting combined elastic and viscous response, or viscoelasticity.
• Dynamic oscillation characterizations are conducted on the HAP materials to characterize the viscoelastic properties, wherein a sample is deformed sinusoidally.
• the test is conducted via a stress sweep, wherein a constant frequency is applied with an increasing stress (amplitude), or conversely a frequency sweep, wherein a constant stress is applied with varied frequency.
• the measured strain of the elastic component of the material will be in phase with the imposed stress, whereas the viscous component of the material will be 90ô out of phase.
• the tan ⁇ is the ratio of the viscous to elastic components of the material, and characterizes the material as exhibiting more viscous or elastic properties.
• a material having a tan ⁇ of greater than 1 at a specific frequency would exhibit predominantly viscous behavior, and a tan ⁇ less than 1 would exhibit predominantly elastic behavior.
• the HAP may be utilized as the sole retention/drainage aid.
• this polymer may be employed in combination with at least one flocculant, such as a conventional papermaking flocculent—e.g., a high MW cationic, anionic, or nonionic flocculent.
• the method of the invention can be practiced using a papermaking apparatus or system as discussed herein. It is emphasized that the inventive method is not limited to this particular apparatus or system, which is only provided as a representative example of what can be employed.
• pulp components are usually metered into the machine stock chest at a consistency level between 2.8 and 3.2 wt %.
• the machine stock chest will usually contain the final mixture, although in some instances, small concentrations of additives may be added just prior to the headbox.
• the machine chest stock is usually circulated to a constant head tank (stuff box), which feeds the stock through a control valve (the basis weight valve) into the paper machine approach system.
• the heart of the approach system is the fan pump which serves to mix the stock with the white water and deliver the blend to the headbox.
• the stock is combined with the circulating white water from the wire pit, and the consistency is reduced to the level required at the headbox (usually between about 0.5 wt % and about 1.0 wt % consistency).
• the white water which typically has a solids concentration of about 0.1 weight percent or less, is liquid from the dewatering of the pulp slurry on the papermaking wire that drains into the wire pit.
• the pulp slurry After the fan pump, the pulp slurry typically passes through a centrifugal cleaner, and then through a pressure screen, to a head box.
• the centrifugal cleaner removes debris such as shives and slivers, and the pressure screen removes gross contamination and deflocs the fibers.
• the headbox serves to distribute the stock onto the earlier indicated endless moving papermaking wire or fabric; this may be a Fourdrinier wire or a twin wire former.
• the slurry On the moving papermaking wire or fabric the slurry is dewatered; the resulting liquid is the white water as discussed above, draining from the slurry into the wire pit. This drainage forms the slurry into a sheet as it is carried on the wire or fabric to the press section.
• the sheet Traveling through the press section, the sheet is pressed between rollers and thereby subjected to further dewatering.
• the sheet continues through the press section into a dryer section, wherein it is additionally dried. From the dryer section the sheet continues through a calender stack. In the calender stack it is pressed between metal rollers to reduce thickness and smooth the surface.
• the resultant paper may also be surface coated with a sizing agent or coating material.
• the materials utilized in the method of the invention include cellulosic pulp and at least one HAP. There can also be employed one or more additional materials, including at least one starch, at least one filler, at least one inorganic or organic coagulant, and at least one conventional flocculent.
• the flocculant and the HAP may be added simultaneously, or at different points in the method without an intermittent shear point, or at different points with an intermittent shear point between their respective additions.
• the flocculant and the HAP are introduced into the method of the invention sequentially, i.e., at different points or times.
• the flocculant may be added before or after the HAP.
• a shear may be affected to the stock between the addition of the flocculant and HAP when added sequentially.
• high shear is effected at the fan pump, centrifugal cleaner, and pressure.
• the apparatus or system preferably is provided with suitable feed points for adding the previously discussed materials, such as the flocculant and the HAP.
• the flocculant and/or the HAP may be added at a feed point before the fan pump (e.g., between the basis weight valve and the fan pump), and/or at a feed point before the centrifugal cleaner (e.g., between the fan pump and the centrifugal cleaner), and/or at a feed point before the pressure screen (e.g., between the centrifugal cleaner and the pressure screen).
• starch, filler, or coagulant may be added at numerous points within the process as is known to those skilled in the art.
• Suitable cellulosic fiber pulps for the method of the invention include conventional papermaking stock such as traditional chemical pulp. For instance, bleached and unbleached sulfate pulp and sulfite pulp, mechanical pulp such as groundwood, thermomechanical pulp, chemi-thermomechanical pulp, recycled pulp such as old corrugated containers, newsprint, office waste, magazine paper and other non-deinked waste, deinked waste, and mixtures thereof, may be used.
• Starch adds strength properties, particularly dry strength, to the cellulosic product obtained from the method of the invention. Particularly, starch increases interfiber bonding in the stock. Starch will also affect drainage properties.
• Starches that may be used in the method of the invention include cationic and amphoteric starches. Suitable starches include those derived from corn, potato, wheat, rice, tapioca, and the like.
• Cationicity is imparted by the introduction of cationic groups, and amphotericity by the further introduction of anionic groups.
• cationic starches may be obtained by reacting starch with tertiary amines or with quaternary ammonium compounds, e.g., dimethylaminoethanol and 3-chloro-2-hydroxypropyltrimethylammonium chloride.
• Cationic starches preferably have a cationic degree of substitution (D.S.)—i.e., the average number of cationic groups substituted for hydroxyl groups per anhydroglucose unit—of from about 0.01 to about 1.0, more preferably about 0.01 to about 0.10, more preferably about 0.02 to 0.04.
• Amphoteric starches can be provided by the introduction of various different anionic groups.
• Preferred amphoteric starches are those with a net cationicity.
• anionic phosphate groups can be introduced into cationic starches through reaction with phosphate salts or phosphate etherifying reagents.
• the amount of phosphate reagent employed in the modification preferably is that which will provide about 0.07-0.18 mole of anionic groups per mole of cationic groups.
• amphoteric starches that may be used are those made by introduction of sulfosuccinate groups into cationic starches. This modification is accomplished by adding maleic acid half-ester groups to a cationic starch and reacting the maleate double bond with sodium bisulfite.
• cationic starch can be etherified with 3-chloro-2-sulfopropionic acid, carboxyl groups can be introduced into starches by reaction with sodium chloroacetate or by hypochlorite oxidation, and propane sultone can be employed to treat cationic starches to provide amphotericity.
• amphoteric starches can be obtained by xanthation of diethylaminoethyl- and 2-(hydroxypropyl)trimethylammonium starch ethers.
• the modification can be extended by the introduction of nonionic or hydroxyalkyl groups from treatment with ethylene oxide or propylene oxide.
• Starch is preferably employed, in the method of the invention, in a proportion of from about 1 lb. per ton to about 100 lbs. per ton of cellulosic pulp, based on the dry weight of the pulp.
• the starch concentration is more preferably from about 2.5 lbs. per ton to about 50 lbs. per ton, and still more preferably from about 5 lbs. per ton to about 25 lbs. per ton, of the pulp.
• Filler provides optical properties to the cellulosic product. It provides opacity and brightness to the finished sheet, and improves its printing properties. Fillers which are suitable include calcium carbonate (both naturally occurring ground carbonate and synthetically produced precipitated carbonate), titanium oxide, talc, clay, and gypsum. The amount of filler employed can be that which results in a cellulosic product of up to about 50 weight percent filler, based on the dry weight of the pulp.
• the coagulant is utilized in addition to the flocculant and HAP to enhance retention and drainage.
• the employed coagulant may be either inorganic or organic.
• the most common inorganic coagulant is an alumina species. Suitable examples include technical grade aluminum sulfate (alum), polyaluminum chloride, polyhydroxy aluminum chloride, polyhydroxy aluminum sulfate, sodium aluminate, and the like.
• the organic coagulant is typically a synthetic, polymeric material. Suitable examples include polyamines, poly(amido amines), polyDADMAC, polyethyleneimine, hydrolyzates and quaternized hydrolyzates of N-vinyl formamide polymers and copolymers, and the like.
• the coagulant is preferably employed, in the method of the invention, in a proportion of from about 0.05 lb. per ton to about 50 lbs. per ton of cellulosic pulp, based on the dry weight of the pulp.
• the coagulant concentration is more preferably from about 0.5 lbs. per ton to about 20 lbs. per ton, and still more preferably from about 1 lb. per ton to about 10 lbs. per ton, of the pulp.
• Ionic flocculants conventional in the papermaking art are suitable as flocculants for the method of the present invention.
• Polymers suitable as flocculants in the method of the invention include homopolymers of a nonionic ethylenically unsaturated monomer.
• Copolymers of monomers comprising two or more nonionic ethylenically unsaturated monomers can also be used, as can copolymers of monomers comprising at least one nonionic ethylenically unsaturated monomer and at least one cationic ethylenically unsaturated monomer and/or at least one anionic ethylenically unsaturated monomer.
• nonionic, cationic, and anionic ethylenically unsaturated monomers which may be employed are those discussed herein as being appropriate for the at least one HAP of the invention.
• Suitable nonionic ethylenically unsaturated monomers include acrylamide; methacrylamide; N-alkylacrylamides, such as N-methylacrylamide; N,N-dialkylacrylamides, such as N,N-dimethylacrylamide; methyl acrylate; methyl methacrylate; acrylonitrile; N-vinyl methylacetamide; N-vinyl methyl formamide; vinyl acetate; N-vinyl pyrrolidone; hydroxyalkyl(meth) acrylates such as hydroxyethyl(meth) acrylate or hydroxypropyl(meth) acrylate; mixtures of any of the foregoing and the like.
• acrylamide, methacrylamide, and the N-alkylacrylamides are preferred, with acrylamide being particularly preferred.
• cationic ethylenically unsaturated monomers which may be used are diallylamine, the (meth)acrylates of dialkylaminoalkyl compounds, the (meth)acrylamides of dialkylaminoalkyl compounds, the N-vinylamine hydrolyzate of N-vinylformamide, and the salts and quaternaries thereof.
• the N,N-dialkylaminoalkyl acrylates and methacrylates, and their acid and quaternary salts are preferred, with the methyl chloride quaternary of N,N-dimethylaminoethylacrylate being particularly preferred.
• suitable examples include those of the following general formulae:
• R 1 is hydrogen or methyl
• R 2 is hydrogen or lower alkyl of C 1 to C 4
• R 3 and/or R 4 are hydrogen, alkyl of C 1 to C 12 , aryl, or hydroxyethyl
• R 2 and R 3 or R 2 and R 4 can combine to form a cyclic ring containing one of more hetero atoms
• Z is the conjugate base of an acid
• X is oxygen or NR 1 wherein R 1 is as defined above, and A is an alkylene group of C 1 to C, 2 ; or
• R 5 and R 6 are hydrogen or methyl
• R 7 is hydrogen or alkyl of C 1 to C 12
• R 8 is hydrogen, alkyl of C 1 to C 12 , benzyl, or hydroxyethyl
• Z is as defined above; or N-vinylformamides and the associated hydrolyzates as represented by recurring units of
• R 1 , R 2 and R 3 are each H or C 1 to C 3 alkyl, and Z is defined above.
• Suitable anionic ethylenically unsaturated monomers include acrylic acid, methylacrylic acid, and their salts; 2-acrylamido-2-methyl-propane sulfonate; sulfoethyl-(meth)acrylate; vinylsulfonic acid; styrene sulfonic acid; and maleic and other dibasic acids and their salts.
• Acrylic acid, methacrylic acid and their salts are preferred, with the sodium and ammonium salts of acrylic acid being particularly preferred.
• the monomers may be polymerized into polymer by a number of initiator systems, including free radical (thermal and redox methods), cationic, and anionic synthesis methods.
• the flocculant polymer may be prepared by a number of commercial means, including bulk polymerization, solution polymerization, dispersion polymerization, and emulsion/inverse emulsion polymerization.
• the resultant polymer may be provided to the end use in a number of physical forms, including aqueous solution, dry solid powder, dispersion, and emulsion form.
• the flocculant may be non-ionic, cationic, anionic, or amphoteric.
• Non-ionic polymer flocculants will contain one or more of the previously described non-ionic monomers.
• Cationic polymer flocculants will contain one or more of the cationic monomers described above.
• the level of total cationic monomer based upon molar concentrations, will range from about 1 to about 99%, preferably from about 2 to about 50%, and still more preferably from about 5 to about 40 mole % cationic monomer, with the remaining monomer being one of the previously described non-ionic monomers.
• Anionic polymer flocculants will contain one or more of the anionic monomers described above.
• the level of total anionic monomer based upon molar concentrations, will range from about 1 to about 99%, preferably from about 2 to about 50%, and still more preferably from about 5 to about 40 mole % cationic monomer, with the remaining monomer being one of the previously described non-ionic monomers.
• Amphoteric polymer flocculants will contain a combination of one or more of the described cationic and anionic monomers. Any combination of cationic and anionic monomer(s) are preferred, provided at least one cationic and one anionic monomer are utilized.
• the polymer may contain an excess of cationic monomer, an excess of anionic monomer, or equivalent amounts of both cationic and anionic monomers.
• the level of total ionic monomer being the combined amount of both cationic and anionic monomers, based upon molar concentrations, will range from about 1 to about 99%, preferably from about 2 to about 80%, and still more preferably from about 5 to about 40 mole % cationic monomer, with the remaining monomer being one of the previously described non-ionic monomers.
• the flocculant is preferably employed, in the method of the invention, in a proportion of from about 0.01 lb. per ton to about 10 lbs. per ton of cellulosic pulp, based upon active polymer weight and on the dry weight of the pulp.
• the concentration of flocculant is more preferably from about 0.05 lb. per ton to about 5 lbs. per ton, and still more preferably from about 0.1 lb. per ton to about 1 lb. per ton, of the pulp.
• the invention comprises at least one HAP.
• Suitable HAPs of the invention include copolymers comprising at least one hydrophobic ethylenically unsaturated monomer with the proviso that the at least one hydrophobic ethylenically unsaturated monomer does not contain 2,4,6-triphenoethyl benzene. These copolymers further include at least one nonionic ethylenically unsaturated monomer, and/or at least one cationic ethylenically unsaturated monomer, and/or at least one anionic ethylenically unsaturated monomer.
• the indicated hydrophobic ethylenically unsaturated monomers include water-insoluble hydrophobic ethylenically unsaturated monomers. Further as to the hydrophobic ethylenically unsaturated monomers, they include ethylenically unsaturated monomers, particularly water-insoluble monomers and monomeric surfactants, having hydrophobic groups.
• the hydrophobic groups include hydrophobic organic groups, such as those having hydrophobicity comparable to one of the following: aliphatic hydrocarbon groups having at least four carbons such as C 4 to C 20 alkyls and cycloalkyls; polynuclear aromatic hydrocarbon groups such as benzyls, substituted benzyls and naphthyls with the proviso that the substituted benzyl group is not 2,4,6-triphenoethyl benzene; alkaryls wherein alkyl has one or more carbons; haloalkyls of four or more carbons, preferably perfluoroalkyls; polyalkyleneoxy groups wherein the alkylene is propylene or higher alkylene and there is at least one alkyleneoxy unit per hydrophobic moiety.
• the preferred hydrophobic groups include those having at least 4 carbons or more per hydrocarbon group, such as the C 4 -C 20 alkyl groups or those having at least 4 carbons or more per perfluorocarbon group, such as the C 4 F 9 -C 20 F 41 . Particularly preferred are the C 8 -C 20 alkyl groups.
• Suitable hydrocarbon group-containing ethylenically unsaturated monomers include the esters or amides of the C 4 and higher alkyl groups.
• esters include dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, nonyl- ⁇ -phenyl acrylate, nonyl- ⁇ -phenyl methacrylate, dodecyl- ⁇ -phenyl acrylate, and dodecyl- ⁇ -phenyl methacrylate.
• the C 10 -C 20 alkyl esters of acrylic and methacrylic acid are preferred. Of these, dodecyl acrylate and methacrylate are particularly preferred.
• hydrocarbon group-containing ethylenically unsaturated monomers may be used:
• N-alkyl ethylenically unsaturated amides such as N-octadecyl acrylamide, N-octadecyl methacrylamide, N,N-dioctyl acrylamide and similar derivatives thereof;
• ⁇ -olefins such as 1-octene, 1-decene, 1-dodecene, and 1-hexadecene;
• vinyl esters wherein the ester has at least eight carbons such as vinyl laurate and vinyl stearate
• vinyl ethers such as dodecyl vinyl ether and hexadecyl vinyl ether
• N-vinyl amides such as N-vinyl lauramide and N-vinyl stearamide
• -alkylstyrenes such as t-butyl styrene
• -alkyl polyethyleneglycol (meth)acrylates such as laurylpolyethoxy(23) methacrylate
• N-alkyl ethylenically unsaturated cationic monomers such as the C 10 -C 20 , alkyl halide quaternary salts of methyldiallyamine, N,N-dimethylaminoalkyl(meth)acrylates, and N,N-dialkylaminoalkyl(meth)acrylamides.
• Suitable nonionic ethylenically unsaturated monomers include acrylamide; methacrylamide; N-alkylacrylamides, such as N-methylacrylamide; N,N-dialkylacrylamides, such as N,N-dimethylacrylamide; methyl acrylate; methyl methacrylate; acrylonitrile; N-vinyl methylacetamide; N-vinyl methyl formamide; vinyl acetate; N-vinyl pyrrolidone; mixtures of any of the foregoing and the like.
• acrylamide, methacrylamide, and the N-alkylacrylamides are preferred, with acrylamide being particularly preferred.
• cationic ethylenically unsaturated monomers which may be used are diallylamine, the (meth)acrylates of dialkylaminoalkyl compounds, the (meth)acrylamides of dialkylaminoalkyl compounds, the N-vinylamine hydrolyzate of N-vinylformamide, and the salts and quaternaries thereof.
• the N,N-dialkylaminoalkyl acrylates and methacrylates, and their acid and quaternary salts, are preferred, with the methyl chloride quaternary of N,N-dimethylaminoethylacrylate being particularly preferred.
• R 1 is hydrogen or methyl
• R 2 , R 3 and R 4 are hydrogen, alkyl of C 1 to C 3 , or hydroxyethyl
• R 2 and R 3 or R 2 and R 4 can combined to form a cyclic ring containing one or more hetero atoms
• Z is the conjugate base of an acid
• X is oxygen or NR 1 wherein R 1 is as defined above
• A is an alkylene group of C 1 to C 12 ; or
• R 5 and R 6 are hydrogen or methyl
• R 7 and R 8 are hydrogen, alkyl of C 1 to C 3 , or hydroxyethyl
• Z is as defined above
• R 1 , R 2 and R 3 are each H or C 1 to C 3 alkyl, and Z is defined above.
• Suitable anionic ethylenically unsaturated monomers include acrylic acid, methylacrylic acid, and their salts; 2-acrylamido-2-methyl-propane sulfonate; sulfoethyl-(meth)acrylate; vinylsulfonic acid; styrene sulfonic acid; and maleic and other dibasic acids and their salts.
• Acrylic acid, methacrylic acid and their salts are preferred, with the sodium and ammonium salts of acrylic acid being particularly preferred.
• the proportion of hydrophobic ethylenically unsaturated monomer in the HAP is within a range which renders the polymer hydrophobically associative—i.e., the hydrophobic monomer concentration is low enough so that the polymer is still water soluble or dispersible, but sufficient to provide the associative property as discussed herein.
• the at least one HAP preferably comprises about 0.001 mole percent to about 10 mole percent—more preferably about 0.01 mole percent to about 5 mole percent, and still more preferably about 0.1 mole percent to about 2.0 mole percent—of the at least one hydrophobic ethylenically unsaturated monomer.
• the HAPs used in the invention include anionic, nonionic, and cationic and amphoteric copolymers. Of these, the anionic copolymers are preferred.
• the anionic copolymers comprise at least one hydrophobic ethylenically unsaturated monomer and at least one anionic ethylenically unsaturated monomer.
• the anionic copolymers further comprise at least one nonionic ethylenically unsaturated monomer.
• Particularly preferred are the terpolymers consisting of, or consisting essentially of, or substantially of, at least one hydrophobic ethylenically unsaturated monomer, at least one anionic ethylenically unsaturated monomer, and at least one nonionic ethylenically unsaturated monomer.
• the preferred hydrophobic ethylenically unsaturated monomers are the hydrocarbon esters of ⁇ , ⁇ -ethylenically unsaturated carboxylic acids and their salts, with dodecyl acrylate and dodecyl methacrylate being particularly preferred.
• Preferred nonionic ethylenically unsaturated monomers are acrylamide and methacrylamide.
• Preferred anionic ethylenically unsaturated monomers are acrylic acid and methacrylic acid.
• the anionic copolymers preferably comprise about 0.001 mole percent to about 10 mole percent hydrophobic ethylenically unsaturated monomer, about 1 mole percent to about 99.999 mole percent nonionic ethylenically unsaturated monomer, and about 1 mole percent to about 99.999 mole percent of the at least one anionic ethylenically unsaturated monomer.
• they comprise about 0.01 mole percent to about 5 mole percent of the at least one hydrophobic ethylenically unsaturated monomer, about 10 mole percent to about 90 mole percent of the at least one nonionic ethylenically unsaturated monomer, and about 10 mole percent to about 90 mole percent of the at least one anionic ethylenically unsaturated monomer.
• they comprise about 0.1 mole percent to about 2.0 mole percent of the at least one hydrophobic ethylenically unsaturated monomer, about 50 mole percent to about 70 mole percent of the at least one nonionic ethylenically unsaturated monomer, and about 30 mole percent to about 70 mole percent of the at least one anionic ethylenically unsaturated monomer.
• the monomers may be polymerized into a HAP polymer by a number of initiator systems, including free radical (thermal and redox methods), cationic, and anionic synthesis methods.
• the HAP may be prepared by a number of commercial means, including bulk polymerization, solution polymerization, micellar solution polymerization, dispersion polymerization, and emulsion/inverse emulsion polymerization.
• the resultant polymer may be provided to the end use in a number of physical forms, including aqueous solution, dry solid powder, dispersion, and emulsion form.
• the HAP is preferably employed, in the method of the invention, in a proportion of from about 0.01 lb. per ton to about 10 lbs. per ton of cellulosic pulp, based on the dry weight of the pulp.
• the concentration of HAP is more preferably from about 0.05 lb. per ton to about 5 lbs. per ton, and still more preferably from about 0.1 lb. per ton to about 1 lb. per ton, of the pulp.
• the method of the invention may yet additionally include conventional additives employed in their usual amounts for their usual purposes. Suitable examples include sizing, promoters, strength agents, dye fixatives, polymeric coagulants, and the like.
• the produced paper may also be surface treated with a surface size or coating material.
• a factor affecting the concentration of HAP in the cellulosic composition of the invention is the proportion of the polymer added during the preparation method.
• the cellulosic composition of the invention which preferably is a cellulosic sheet, and more preferably is paperboard or paper—preferably comprises about 0.01 to about 10 weight percent—more preferably about 0.05 weight percent to about 5 weight percent, and still more preferably about 0.1 weight percent to about 1 weight percent—of the HAP, based on the dry weight of the composition.
• HAPs used in the invention are prepared from acrylamide (AM), acrylic acid (AA), and lauryl acrylate (LA).
• Control polymers, the anionic copolymers I and IV, are prepared without the hydrophobically modified monomer lauryl acrylate—i.e., from acrylamide and acrylic acid alone.
• Polymers I-VII are all prepared by solution polymerization. The relative proportions of monomers used in each instance are set forth below. TABLE I Solution Polymer Sample Description Polymer Monomers Feed Ratio (mole %) I (control) AA/AM 45/55 II AA/AM/LA 45/54/1 III AA/AM/LA 45/54/1 IV (control) AA/AM 30/70 V AA/AM/LA 30/69.5/0.5 VI AA/AM/LA 30/69/1 VII AA/AM/LA 30/68/2
• Polymers V, VI and VII are prepared in the same manner, except for the ratio of the monomers.
• the monomer ratio is 3.4 parts of acrylamide, 0.1 part (0.5 mol % of the monomers) of lauryl acrylate, and 1.5 parts of acrylic acid.
• the monomer ratio is 3.4 parts of acrylamide, 0.19 parts (1 mol % of the monomers) of lauryl acrylate, and 1.5 parts of acrylic acid.
• the monomer ratio is 3.4 parts of acrylamide, 0.38 parts (2 mol % of the monomers) of lauryl acrylate, and 1.5 parts of acrylic acid.
• Polymer I is prepared using the same method and proportions as with Polymers II and III, except without the lauryl acrylate.
• Polymer IV is prepared in the same manner as Polymer I, except that for Polymer IV the monomer ratio is 3.5 parts of acrylamide and 1.5 parts of acrylic acid.
• Hydrophobic associative polymers are prepared via dispersion polymerization. TABLE 2 Brine Dispersion Sample Description Feed Ratio Polymer Monomer (mole %) VIII (control) AA/AM 50/50 IX AA/AM/LMA 49.9/50/0.1 X AA/AM/LMA 49.8/50/0.2 XI AA/AM/LA 50/49.75/0.25 XII AA/AM/LA 50/49.5/0.5
• Viscosity and rheological characterizations are further conducted on Samples IV through VII to demonstrate the associative properties of the modified samples compared to the unmodified control.
• the described studies are conducted at 0.5% aqueous solution. As is exhibited previously in Table 3, Brookfield viscosity at 12 rpm is conducted on the samples, exhibiting a significant increase in apparent viscosity with increased levels of hydrophobe. The highest level of hydrophobe exhibits a 10 fold increase in Brookfield Viscosity due to associative interactions. Additional studies are also conducted with a Haake RS-75 controlled stress rheometer equipped with a cone and plate geometry, with a 60 mm diameter cone and a fixed angle of 2 degrees.
• the apparent viscosity of the 0.5% solid content polymer samples is determined at a constant shear rate of 10 sec ⁇ 1 , with similar results observed as with the Brookfield viscometer, in that a 10 fold increase in viscosity is observed with the highest level of hydrophobe, indicating strong associative behavior.
• a stress sweep is conducted with the instrument in dynamic stress oscillation mode, at a constant 1 Hz frequency, and a stress range of 0.1 to 10.0 Pa in 20 logarithmic steps.
• the G′ storage modulus is assigned as the equilibrium value in the linear viscoelastic region, and is defined as:
• the G′ storage modulus is also referred to as the gel modulus, and is taken as an indication of the degree and strength of the network structure, as determined by the inter-/intra-molecular hydrophobic associations. At equivalent applied stress, materials with a higher G′ value will strain or deform less, thus exhibiting a stronger gel complex or network structure.
• the data demonstrates a linear relationship between hydrophobe concentration and G′ storage modulus, with the modulus increasing with increased level of hydrophobe, and the highest G′ storage modulus for the highest level of hydrophobic substitution.
• the unmodified Polymer IV exhibits a storage modulus of 2 Pa
• the modified Polymer VII containing 2 mole % lauryl acrylate exhibits a storage modulus of 25.6 Pa.
• a frequency sweep in dynamic oscillation mode is subsequently conducted with the instrument in dynamic oscillation mode, at a constant stress of 0.1 Pa, and a frequency range of 0.0068 Hz to 10 Hz with 3 readings per frequency decade.
• the tan ⁇ is the ratio of the loss (viscous) modulus to storage (elastic) modulus, determined according to:
• the dispersion polymers are characterized according to equivalent methods as described in the solution polymerization polymers.
• the data presented in Table 5 demonstrates similar results as with the solution polymerization products.
• the 0.5% solution apparent viscosity is observed to increase with the introduction of the hydrophobic monomer.
• a stress sweep study in dynamic oscillation mode demonstrates a G′ storage modulus increase with samples IX and XI compared to the unmodified control sample VIII.
• a frequency sweep study in dynamic oscillation mode demonstrates a low tan ⁇ for the hydrophobic associative polymer compared to the unmodified control.
• the dilute solution viscosity properties of the Table 5 HAP samples were determined in aqueous solutions at various concentrations of NaCl and compared to Polyflex CP.3, a commercial polyacrylamide drainage aid (Cytec Industries, Inc., West Patterson, N.J.) and Polymer E, a commercial high MW anionic polyacrylamide flocculent. The data are presented in Table 5.1. As discussed in Introduction to Physical Polymer Science by L. H. Sperling (Wiley Interscience, 1992), the dilute solution properties provide a relative indication of polymer molecular weight. In this experiment, the solvent viscosity ⁇ 0 is compared to the polymer solution viscosity ⁇ . The relative viscosity is the unitless ratio of the two:
• the reduced specific viscosity referred to hereafter as the RSV, is the specific viscosity divided by the polymer concentration (C) in gram per deciliter units:
• the units for RSV are deciliter per gram (dL/g), and as such describe the hydrodynamic volume (HDV) of a polymer in solution. Thus a higher RSV indicates a large HDV in solution, and a higher MW when comparing conventional polymers.
• the experiment is conducted in the dilute regime such that no polymer coil overlap is occurring.
• the RSV values can be determined by capillary or rotational viscometer methods by measuring the respective efflux time or apparent viscosity of both the solvent and the polymer solutions.
• the data described in Table 5.1 were determined with a Brookfield rotational viscometer equipped with an ultra-low (UL) adapter, capable of determining the viscosity of low viscosity solutions.
• the data demonstrate the effect on polyelectrolyte RSV with varying salt concentrations, as is well known to those skilled in the art.
• the inventive HAP products demonstrate a higher RSV in 1 M NaCl that contains an additional 0.1% nonylphenol ethoxylate (NPE) surfactant than in 1 M NaCl only.
• NPE nonylphenol ethoxylate
• This phenomena which shall be referred to as “RSV Ratio”
• RSV Ratio is a dilute solution property specific to associative polymers containing hydrophobes, and does not occur in linear, cross-linked, or branched polymers.
• the RSV Ratio is observed to increase dramatically with higher levels of hydrophobic monomer, and does not occur in the control polymer, Polyflex CP.3, or Polymer E.
• a first series of Britt jar retention tests and Canadian Standard Freeness (CSF) drainage tests are conducted to compare the performance of the HAPs of the invention, with those of the following: a non-hydrophobic associative polymer; a conventional anionic polyacrylamide flocculant; and inorganic and organic drainage aids commonly referred to within the industry as “microparticles” or “micropolymers”.
• CSF Canadian Standard Freeness
• the Britt jar (Paper Research Materials, Inc., Gig Harbor, Wash.) retention test is known in the art. In the Britt jar retention test a specific volume of furnish is mixed under dynamic conditions and an aliquot of the furnish is drained through the bottom screen of the jar, so that the level of fine materials which are retained can be quantified.
• the Britt jar utilized for the present tests is equipped with 3 vanes on the cylinder walls to induce turbulent mix, and a 76 ⁇ screen in the bottom plate is utilized.
• the CSF device (Lorentzen & Wettre, Code 30, Sweden) utilized to determine relative drainage rate or dewatering rate also is known in the art (TAPPI Test Procedure T-227).
• the CSF device comprises a drainage chamber and a rate measuring funnel, both mounted on a suitable support.
• the drainage chamber is cylindrical, fitted with a perforated screen plate and a hinged plate on the bottom, and with a vacuum tight hinged lid on the top.
• the rate measuring funnel is equipped with a bottom orifice and a side, overflow orifice.
• the CSF test is conducted by placing 1 liter of furnish, typically at 0.30% consistency, in the drainage chamber, closing the top lid, and then immediately opening the bottom plate. The water is allowed to drain freely into the rate measuring funnel; water flow which exceeds that determined by the bottom orifice will overflow through the side orifice and is collected in a graduated cylinder. The values generated are described in millimeters (mls) of filtrate; higher quantitative values represent higher levels of dewatering.
• the furnish employed in this first series of tests is a synthetic alkaline furnish.
• This furnish is prepared from hardwood and softwood dried market lap pulps, and from water and further materials.
• First the hardwood and softwood dried market lap pulp are separately refined in a laboratory Valley Beater (Voith, Appleton, Wis.) These pulps are then added to an aqueous medium.
• the aqueous medium utilized in preparing the furnish comprises a mixture of local hard water and deionized water to a representative hardness.
• Inorganic salts are added in amounts so as to provide this medium with a representative alkalinity and a total conductivity.
• the hardwood and softwood are dispersed into the aqueous medium at typical weight ratios of hardwood and softwood.
• Precipitated calcium carbonate (PCC) is introduced into the furnish at 25 weight percent, based on the combined dry weight of the pulps, so as to provide a final finish comprising 80% fiber and 20% PCC filler.
• the Britt jar retention tests in this first series are conducted with 500 mls of the synthetic furnish, having a typical solids concentration of 0.5%.
• the test is conducted at a constant rpm speed according to the following parameters, consistent with the sequence set forth in Table 2: add starch, mix; add alum, mix; add polymer flocculant, mix; add drainage aid, mix; obtain filtrate.
• the cationic potato starch utilized is Stalok 600 (A. E. Staley, Decatur, Ill.), and the alum is aluminum sulfate-octadecahydrate available as a 50% solution (Delta Chemical Corporation, Baltimore, Md.).
• the cationic flocculant utilized, referred to as CPAM-P is a 90/10 mole % acrylamide/N,N-dimethylaminoethylacrylate methyl chloride quaternized; this material is commercially available as a self-inverting water-in-oil emulsion.
• the retention values reported in Table 2 are fines retention where the total fines in the furnish is first determined by washing” 500 mls of furnish with 10 liters of water under mixing conditions to remove all the fine particles, defined as particles smaller than the Britt jar 76 ⁇ screen. The fines retention for each treatment is then determined by draining 100 mls of filtrate after the described addition sequence, then filtering the filtrate through a pre-weighed 1.5 ⁇ filter paper. The fines retention are calculated according to the following equation:
• Fines retention (filtrate wt ⁇ i minus) fines wt)/filtrate wt
• the CSF drainage tests are conducted with 1 liter of the furnish at a solids concentration of 0.30%.
• the furnish is prepared for the described treatment externally from the CSF device, utilizing equivalent speeds and mixing times as described for the Britt jar tests, in a square beaker to provide turbulent mixing.
• the treated furnish is poured into the top of the CSF device and the test is conducted.
• CSF ADD #1 (active) ADD #2 (active) Polymer (active) Drainage Aid (active) % Ret mls Cationic Potato Starch 10 Alum 5 none 27 29 395 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0 5 none 0 48 43 380 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0 5 Polymer II 0 75 69 54 620 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0 5 Polymer I 0 75 50 46 535 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0 5 Polymer E 0 75 53 16 540 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0.5 Polyflex CP.3 0 75 77 85 650 Cationic Potato Starch 10 alum 5 CPAM-P Flocculant 0.5 Bentolite HS 4 64 72 600
• the PDD is equipped with a rotating hydrofoil, and vacuum capability underneath a wire screen. It is an instrument developed internally (described in U.S. Pat. No. 5,314,581) as a reasonable simulation of the actual retention, drainage, and sheet formation operations. During the operation of the experiment, a vacuum is applied to the fibrous slurry to assist in the formation of a fibrous mat, and the vacuum is continued until a steady state equilibrium vacuum is achieved.
• the PDD can be used in determining first pass retention, peak vacuum, equilibrium vacuum, peak to equilibrium vacuum ratio (PEVR), and vacuum drainage time.
• PEVR peak to equilibrium vacuum ratio
• the first pass fines retention is determined by mass balance calculations involving the weight of the final sheet, the total mass introduced into the PDD, and the total fines fraction of the stock which is defined as the fraction of the stock that has a particle size less than 76 ⁇ . As with Britt jar fines retention, higher values indicate the desired response.
• the peak vacuum is the total vacuum required during mat formation until air is drawn through the formed mat and the vacuum is disrupted.
• Equilibrium vacuum is the steady state vacuum drawn through the formed sheet. Both peak vacuum and equilibrium vacuum are measured in inches of Hg. A lower quantitative value for the peak vacuum indicates a fibrous matrix that is easier to dewater.
• PEVR peak to equilibrium vacuum ratio
• the vacuum drainage time is the time to peak vacuum, and is measured by the instrument in time units of seconds. It is believed this response is similar to the wet-line on a paper machine, which is the point where the water has drained sufficiently such that the sheet has lost its sheen or visible free water. The wet line position is commonly monitored as an indication of papermachine drainage. The desired responses for the vacuum drainage parameters are reduced (low) values, indicating improved drainage.
• a series of Britt jar retention and CSF tests is conducted with the following: Polymer III, hydrophobically associative anionic polyacrylamide of the invention as discussed herein; Polymers V-VII, hydrophobically associative polymers of the invention, exhibiting sequentially increased levels of hydrophobic modification; Polymer IV, an unmodified anionic polyacrylamide control polymer as discussed herein; Polymer E; and Polyflex CP.3.
• the tests are conducted according to the methods previously described.
• the data demonstrates the superior activity of the invention provided by Polymer III and Polymer VII, compared to the unmodified control Polymer IV. Increased retention and drainage activity are observed with increased level of hydrophobic substitution, with Polymer VII approaching the activity of Polyflex CP.3.
• the data is set forth in Table 8.
• the polymeric materials are evaluated at 0.5, 0.75, and 1.0 lbs./ton active polymer, while the bentonite clay is evaluated at 2, 4, and 6 lbs./ton, in accordance with typically utilized mill dosage levels.
• the results are set forth in Table 9.
• the Table 9 data illustrates the activity of the polymer of the invention.
• Polyflex CP.3, bentonite clay, and Polymer III all exhibit positive dose response activity, while Polymer M is not dosage active.
• the Polymer III provides equal to greater retention and drainage activity as compared with bentonite clay.
• Polymer M provides retention and drainage equal to that of Polymer III, but at distinctly higher PEVR; this reduction in sheet uniformity/formation at equal drainage is undesirable.
• the drainage activity of Polymer III approaches that of Polyflex CP.3, as 1.0 lb./ton of Polymer III approaches the drainage of 0.5 lb. /ton Polyflex CP.3. It is again noted that at these equal drainage times, the PEVR of the polymer of the invention is lower than that of Polyflex CP.3, which is an indication of improved sheet uniformity or formation.
• PVAm polyvinylamine
• the PVAm is produced via aqueous solution polymerization of N-vinylformamide monomer, then with a subsequent hydrolysis of the polymer to produce N-vinylamine.
• the subject polymer is hydrolyzed at 90%, such that the resultant copolymer is 90 mole % N-vinylamine/10 mole % N-vinylformamide; the polymer is at 5% solids and exhibits an intrinsic viscosity in 1 M NaCl of 3 dL/g.
• test conditions and associated additives are as those described before, with the exception of the cationic flocculent utilized being CPAM-N; this material is equivalent in composition and physical form as the previously utilized CPAM-P.
• An anionic polyacrylamide flocculant (APAM) is also utilized. This material is a 30 mole % sodium acrylate/70 mole % acrylamide copolymer, commercially available as a self-inverting emulsion.
• the data in Table 12 demonstrates the improved activity of the inventive material.
• Polymers IX and XI demonstrate high retention and drainage activity compared to commercial drainage aid bentonite clay, the control Polymer VIII, and the conventional flocculant Polymer A.
• the Polymers IX, X, and XI also indicate a positive dosage response at low PEVR, while the unmodified control does not demonstrate a remarkable dosage response.
• TABLE 13 10 lbs/ton Cat Potato Starch + 5 % First Vacuum lbs/lon 0 5 lbs/ton Pass VACUUM PEAK Peak to Drainage CPAM-N Flocculant + lbs/ton Fines Gravity Drainage Equilibrium VACUUM Equilibrium Time- Drainage Aid (Active) Retention Time - seconds (in Hg) (in Hg) Vacuum Ratio seconds None 86.1% 3.98 3 33 5 11 1 53 0 94 Polymer VIII 0 5 93 1% 3 76 2 89 4 38 1 52 0 67 Polymer VIII 1 95 6% 3 79 2.72 4 18 1.54 0 63 Polymer IX 0 5 93 7% 3 71 2 77 4 12 1 49 0 64 Polymer IX 1 94 5% 3.64 2.51 3 75 1 50 0 54 Poly

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