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
  • 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
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F3/00—Press section of machines for making continuous webs of paper

Definitions

• This invention relates to a process for improving retention of fillers and pulp fines and increasing rate of dewatering of furnish in the manufacture of paper, as well as to paper products of such process.
• an aqueous pulp suspension, or "furnish" of cellulosic fibers resulting from pulping of the feed wood stock is hydraulically and mechanically conveyed onto a wire grid or screen which is in motion to produce a wet web of cellulosic fibers.
• the wet fiber web is dewatered on the screen, by drainage of liquid therefrom, following which the wet web may be further treated, dried, calendared, and subjected to additional treatments as desired.
• additives are contained in the furnish which is passed to the wire substrate wet web forming means.
• These additives may include processing aids for improving operation of the papermaking machinery, as well as paper chemicals for improvement of the properties of the finished paper product.
• processing aids may include retention aids for the retention of filler additives in and on the resultingly formed web and reduction of loss of paper pulp fines from the furnish during the dewatering step and drainage aids for improving the rate of dewatering of the furnish on the wire forming means.
• Other additives may include formation aids, flocculants, defoamers, wet-web-strength additives, pitch control agents, slimicides, creping aids, and the like, as is well known to those skilled in the art.
• Functional additives may include fillers as mentioned, sizing aids and the like.
• the fillers may include optical brighteners, opacifiers, and pigments.
• Sizing agents are employed to provide the paper product with resistance to wetting by liquids, such as ink, water and the like, and rosin or waxes are typically employed for such purpose.
• retention aids to the furnish prior to the wet web formation step, to neutralize or reduce negatives surface charges inherently present on cellulosic fibers and fines and to cause coflocculation of fillers, fibers and fines so that they cohere, in addition to being bonded by the retention agent.
• a number of retention aids have been employed in prior art, generally containing amine or quarternary ammonium groups, such as diethylenetriamine-adipic acid polyamide treated with epichlorohydrin, polymers of ethylenimine and di- methyldiallylammonium chloride, and aminoethyl acrylates copolymers.
• amine or quarternary ammonium groups such as diethylenetriamine-adipic acid polyamide treated with epichlorohydrin, polymers of ethylenimine and di- methyldiallylammonium chloride, and aminoethyl acrylates copolymers.
• hydrated aluminum sulfate i.e., alum
• various polymers and copolymers of acrylamide, of ionic and nonionic types In particular, polyacrylamides of cationic and anionic type have been employed in combination with alum.
• this invention relates to an additive composition for improving retention of fillers and pulp fines and increasing rate of dewatering of furnish in the manufacture of paper, comprising (a) a water-soluble copolymer containing from about 2.5 to about 35 mole percent repeating units derived from 2-acrylamido-2-methylpropanesulfonic acid, and (b) a water-soluble polymer selected from the group consisting of polyacrylamide, and copolymers containing from. about 70 to about 100 mole percent of repeating units derived from acrylamide wherein the weight ratio of (a) to (b) is from about 8:1 to about 0.125:1.
• an improved process for enhancing retention of fillers and pulp fines and increasing rate of dewatering of furnish in the manufacture of paper comprising adding to said furnish prior to the dewatering thereof (a) from about 0.1 to about 3.0 pounds per ton of said furnish of a water-soluble copolymer containing from about 2.5 to about 35 mole percent repeating units derived from 2-acrylamido-2-methylpropanesulfonic acid, and (b) from about 0.1 to about 5.0 pounds per ton of said furnish of a water-soluble polymer selected from the group consisting of polyacrylamide, and copolymers containing from about 70 to about 100 mole percent of repeating units derived from acrylamide.
• the invention also relates to a paper product of the process as described in the preceding paragraph.
• AMPS 2-acrylamido-2-methylpropanesulfonic acid
• a water-soluble polymer selected from the group consisting of polyacrylamide react synergistically in providing higher levels of retention and rate of dewatering (drainage rate) than is achievable with either component when used alone.
• the composition of the present invention is relatively insensitive to pH and is highly effective in both acid and alkaline systems.
• AMPS polymers and copolymers have been taught as drainage and retention aids in the prior art, e.g., German Offenlegung- sschrift 2,248,752, there has been no recognition that such additives could be used in combination with acrylamide polymers or copolymers in the manner of the present invention, to achieve the enhanced drainage and retention performance levels economically achieved by the composition of the instant invention.
• composition and process of the present invention may be applied with advantage to furnishes of diverse papermaking stock, such as groundwood, thermal mechanical processing (TMP) pulps, kraft feedstocks and the like, and is particularly efficacious in application to newsprint furnishes containing at least 40 percent by weight of groundwood pulp.
• diverse papermaking stock such as groundwood, thermal mechanical processing (TMP) pulps, kraft feedstocks and the like.
• the AMPS copolymer employed in the present invention contains from about 2.5 to about 35, preferably 5-20 and most preferably from 7-15 mole percent repeating units derived from AMPS.
• AMPS is,intended broadly to refer to 2-acrylamido-2-methylpropanesulfonic acid as well as and any suitable salts thereof.
• Suitable AMPS copolymers include those containing for example from about 65 to about 97.5 mole percent of repeating units derived from acrylamide, and from about 3 to about 15 mole percent of repeating units derived from acrylic acid.
• the AMPS copolymer has a molecular weight of from about 2 million to about 20 million.
• Particularly preferred copolymers may for example have a Standard Brookfield viscosity, measured in a 0.20% solution at 25 0 C in 0.33 M NaCl with a #1 spindle rotating at 60 rpm, of 2-10 centipoises.
• the polymeric co-additive employed with the AMPS copolymer is a water-soluble polymer selected from the group consisting of polyacrylamide, and copolymers containing from about 70 to about 100 mole percent of repeating units derived from acrylamide.
• This polymer may be nonionic or ionic in character and is most preferably cationic.
• this polymer may be a cationic emulsion copolymer containing a 95 mole percent repeating units derived from acrylamide and 5 mole percent repeating units derived from dimethylaminoethyl methacrylate which is quaternized with dimethyl sulfate, the copolymer being emulsified with sorbitan monooleate and containing a suitable emulsin breaker.
• this polymer may be a cationic copolymer of acrylamide and diallyldimethylammonium chloride containing 75 to 99 mole percent repeating units derived from acrylamide and having a molecular weight of less than about 25,000.
• Other suitable polymers include aminomethylated polyacrylamide and methacrylamidopropyl trimethylammonium chloride/acryamide copolymers.
• the weight ratio of the AMPS copolymer to the acrylamide polymer or copolymer added to the furnish is in the range of from about 0.125:1 to about 8:1.
• the composition of the invention is particularly effective at a pH in the range of from about 4.0 to about 5.5.
• the composition of the invention may be used, for example, in a furnish containing a rosin size and alum at pH levels below about 5.
• the composition of the instant claimed invention may be employed with conventional retention and drainage aid promoter compounds, such as diallyldimethylammonium chloride polymers or copolymers and polyethyleneimine.
• the tabulated values for consistency were measured by filtering a weighed stock sample, then drying the retained fiber and weighing same. Mobility was measured in units of at the stationary layer in a micro- electrophoresis cell.
• the values set forth for "CD" represent the cationic demand for the furnish, measured as the dosage, in lbs./ton of furnish, of poly(dimethylamino/epi- chlorohydrin) necessary to reduce the mobility of the furnish sample to zero.
• Headbox samples of the newsprint furnish described in Table I were obtained from a twin wire papermaking machi.ne, which normally has low first pass retention (FPR). The first pass retention.
• FPR x 100% is a measure of the efficiency of the forming section of the papermaking machine in removing suspended material in the headbox furnish (i.e., fibers, fines and fillers) from the stock.
• High first pass retention correlates with low recirculation rates of fines and fillers in the papermaking system and better operation of the wet end of the process.
• a Britt jar was used in the following tests to measure the effect of various additives on first pass retention. Conditions of operation (speed of agitation and serum size) were selected so that the FPR obtained with the Britt jar was the same as the FPR measured on the papermaking machine. The furnish for which the Britt jar was calibrated then was treated with the selected amount of furnish additive and FPR measured again in the Britt jar.
• Drainage measurements were.made in a drainage tube, based on the amount (volume) of filtrate collected in a period of 5 seconds.
• Polymer M is a cationic emulsion copolymer containing 95 mole percent repeating units derived from acrylamide and 5 mole percent repeating units derived from dimethylaminoethyl methacrylate which is quaternized with dimethylsulfate, the copolymer being emulsified with sorbitan monooleate (Arlacel 80, Atlas Division of ICI Americas, Inc.) and Alfonic 1412-60 (Conoco Chemicals Company) emulsion breaker.
• Copolymer A is a copolymer according to the present invention containing twenty mole percent repeating units derived from AMPS and eighty mole percent repeating units derived from acrylamide.
• Copolymer A and Polymer M were again each run separately against a control furnish containing no additives, along with furnishes of the following compositions: Copolymer A in combination with Polymer M, at weight ratios of M/A of 2/1 and 1.24/1; Copolymer A in combination with a cationic polyacrylamide which has been Manniched to a 70% level by reaction with formaldehyde and dimethylamine, hereinafter referred to as Polymer N, at a weight ratio of N/A of 10/1; Copolymer A in combination with an anionic, acrylamide and acrylic acid copolymer containing Alfonic 1412-60, hereinafter referred to as Polymer 0, in a ⁇ weight ratio of 0/A of 1.24/1; Copolymer A in combination with a cationic copolymer of acrylamide and diallyld
• the furnish employed in this series of tests was a newsprint furnish having the following composition: 45 weight % bleached kraft and 55 weight percent groundwood.
• First pass retention was measured with a Britt jar for the additive compositions shown in Table III below, wherein the retention percentage values are tabulated.
• the twin wire papermaking machine for which the Britt jar was calibrated had a measured FPR value of 47.5%, which is high for newsprint due to the high amount of kraft in this furnish.
• the blank control had a first pass retention level of 47.5 percent and retention levels of 80-85% were achieved using Polymer M and Copolymer A separately.
• Copolymer A in combination with Polymers M, N, 0, P and Q, in the manner of the present invention permitted achievement of retention levels as high as 90-95% at comparatively low additive levels, with the compositions of the present invention exemplifying the same marked increase in retention level relative to the separate additives Copolymer A and Polymer M, as previously discussed in Example I above.
• two pounds per ton of Polymer M alone provided a first pass retention level of 69.4 percent
• a combination of 1.14 pounds per ton of Polymer M and 0.91 pounds per ton of Polymer A, representing approximately the same additive total weight provided a retention level of 90.1 and 90.4.
• Copolymer 1 contains 5 mole percent AMPS and 95 mole percent acrylamide units; Copolymer 2 contains 10 percent AMPS and 90 percent acrylamide units; Copolymer 3 contains 15 percent AMPS and 85 percent acrylamide units; Copolymer A is as described in Example I, containing 20 pecent AMPS and 80% acrylamide units; and Copolymer 4 contains 25% AMPS and 75% acrylamide units.
• the percent charge on the copolymer, due to the AMPS repeating units therein, are tabulated in Table IV, together with first pass retention values for dosages of the respective copolymers at .4 pounds per ton, .8 pounds per ton and 1.2 pounds per ton, respectively.
• the respective copolymers were employed in combination with Polymer M, as previously described in Example I, at weight ratios of M/Copolymer of 0.6/0.5 and 1.1/0.9.
• the retention values shown in Table IV clearly show the marked enhancement when the copolymer is used in combination with Polymer M, relative to the use of the copolymer alone.
• the data further show that there is an optimum with respect to percentage charge on the copolymer, at approximately 10-20 percent charge, corresponding compositionally to 10-20 percent AMPS in the copolymer. It is to be noted that above about 20 percent charge (twenty percent AMPS), there is a decreasing level of retention with increased charge levels, both for the copolymer alone and for the copolymer in combination with Polymer M.
• Example III The same copolymers tested in Example III were tested for drainage, alone and in combination with Polymer M. Performance data are shown in Table V below, wherein the same furnish compositions as Example III were employed.
• the 5-second drainage volume for the control sample containing no drainage/retention additives was 22 milliliters.
• Each of the copolymer additives produced substantial increases in drainage, which was further increased by combination with Polymer M in the manner of the present invention. As shown, Polymer M alone produced only a small negative effect on the drainage rate relative to the control sample containing no additives.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)

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• 1984
  • 1984-02-18 EP EP84101696A patent/EP0119493A1/de not_active Withdrawn
  • 1984-02-27 DK DK108984A patent/DK108984A/da not_active Application Discontinuation
  • 1984-03-13 JP JP59046632A patent/JPS59179899A/ja active Pending
  • 1984-03-14 CA CA000449551A patent/CA1223107A/en not_active Expired
  • 1984-03-15 ZA ZA841944A patent/ZA841944B/xx unknown
  • 1984-03-15 BR BR8401185A patent/BR8401185A/pt unknown
  • 1984-03-15 AU AU25665/84A patent/AU562928B2/en not_active Expired - Fee Related
  • 1984-03-15 NO NO841007A patent/NO841007L/no unknown
  • 1984-03-15 KR KR1019840001321A patent/KR840007923A/ko not_active Application Discontinuation
  • 1984-03-15 FI FI841053A patent/FI72555C/fi not_active IP Right Cessation

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