CA1216711A - Manufacture of paper using copolymers of 2-acrylamido- 2-methylpropane sulfonic acid for increasing rate of dewatering of high mechanical/themomechanical pulp furnishes - Google Patents
Manufacture of paper using copolymers of 2-acrylamido- 2-methylpropane sulfonic acid for increasing rate of dewatering of high mechanical/themomechanical pulp furnishesInfo
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- CA1216711A CA1216711A CA000456437A CA456437A CA1216711A CA 1216711 A CA1216711 A CA 1216711A CA 000456437 A CA000456437 A CA 000456437A CA 456437 A CA456437 A CA 456437A CA 1216711 A CA1216711 A CA 1216711A
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- dewatering
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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
- D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
- D21H13/10—Organic non-cellulose fibres
- D21H13/12—Organic non-cellulose fibres from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
-
- 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
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/08—Mechanical or thermomechanical pulp
-
- 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
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Paper (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Train Traffic Observation, Control, And Security (AREA)
- Lubricants (AREA)
- Continuous Casting (AREA)
- Pens And Brushes (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
Abstract
MANUFACTURE OF PAPER USING COPOLYMERS OF
RATE OF DEWATERING OF HIGH MECHANICAL/THERMOMECHANICAL
PULP FURNISHES
Abstract of the Disclosure A process for increasing rate of dewatering in the manufacture of paper from a furnish whose pulp constitu-ent comprises at least 40% by weight of mechanical wood pulp, thermomechanical wood pulp, or mixtures thereof, by addition thereto of air aluminum salt, e.g., alum, and a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acrylamido-2-methylpropane sulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide, while maintaining pH of the furnish in the range of from about 3.5 to about 6.5.
RATE OF DEWATERING OF HIGH MECHANICAL/THERMOMECHANICAL
PULP FURNISHES
Abstract of the Disclosure A process for increasing rate of dewatering in the manufacture of paper from a furnish whose pulp constitu-ent comprises at least 40% by weight of mechanical wood pulp, thermomechanical wood pulp, or mixtures thereof, by addition thereto of air aluminum salt, e.g., alum, and a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acrylamido-2-methylpropane sulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide, while maintaining pH of the furnish in the range of from about 3.5 to about 6.5.
Description
28,666 MANUFACTURE OF PAPER USING COPOLYMERS OF
2-ACRYLAMIDO-2-METH~LPROPANE SULFO~IC ACID FOR INCREASING
. . . _ RATE OF DEWATERING OF HIG~ MECHANICAL/THERM~MECHANICAL
PULP FURNISHES
Background of the Invention Field of the Invention This invention generally relates to a process for increasing rate of dewatering of furnish in the manufacture of paper, and specifically to such a process wherein the pulp constituent of the furnish contains a high content of mechanical and/or thermomechanical pulps.
Description of the Prior Art In the general practice of papermaking, 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.
In general practice, a number of additives are contained in the furnish which is passed to the wire sub-strate (wet web forming means). These additives may include processing aids for improving operation of the papermaking machinery, as well as chemicals for improvement of the properties oE the finished paper product. Suitable pro-cessing aids may include retention aids for the retention oE Eiller additives in and on the resultingly formed web and reduction of loss of paper pulp fincs from the furni~n during the dewatering step and drainage aids for improvir,g the rate of dewatering of the furnish on the wire for~ing means. Other additives may include formation aids, floccu-lants, defoamers, wet and dry strength additives, pitchcontrol agents, slimicides, creping aids, and the like, as is well known to those skilled in the art.
Functional additives may include fillers as men-tioned, sizing aids, strenghtening additives 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.
Based on considerations of efficiency and ease of processing, it is desirable to add drainage aids to the furnish prior to the wet web formation step, to provide in-creased capacity or processing rate in the papermaking pro-cess in systems where dewatering or liquid drainage is the rate-limiting step in the process.
Although it is desirable to maximize drainage rates in the papermkaing system, the additives which here-tofore have been employed for such purpose give rise to low levels of activity when used in newsprint furnishes, which generally are made under strongly acidic and high shear conditions. These include conventional drainage aids contain-ing as anionic substituents -COOH groups, as well as copo-lymeric additives containing -SO3H groups.
As used herein, "newsprint furnish" means a fur-nish for the manufacture of paper and paperboard, particu-larly newsprint, coating raw stock grades and fine paper grades, containing fines and fillers and made under acid conditions, whose pulp constituent comprises at least 40%
by weight of a wood pulp selected from the group consisting of mechanical wood pulp, thermomechanical wood pulp and mixtures thereof.
Accordingly, there is a containing need for im-7 ''i ~
proved dewatering additives for newsprint furnishes char-acterized by stability and high activity It is therefore an object of the present inven-tion to provide a process for increasing rate of dewatering in newsprint Eurnishes at the low pH conditions c'naracter-istic of such furnishes.
SVMMARY OF THE INVENTION
The present invention relates to a process for increasing rate of dewatering in the manufacture of paper from a furnish whose pulp constituent comprises at least 40% by weight of a wood pulp selected from the group con-sisting of mechanical wood pulp, thermomechanical ~ood pulp, and mixtures thereof comprising:
(a) adding to said furnish prior to said dewater-ing thereof (1) from about 0.5 to about 5 percent by weight, based on weight of cellulosic fibers in said furnish, of an aluminum salt, and (2) from about 0.01 to about 0.5 percent by weight, based on weight of cellulosic fibers in said furnish, of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acrylamido-2-methylpropanesulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide; and (b) maintaining pH of said furnish during step (a) and through said dewatering in the range of from about
. . . _ RATE OF DEWATERING OF HIG~ MECHANICAL/THERM~MECHANICAL
PULP FURNISHES
Background of the Invention Field of the Invention This invention generally relates to a process for increasing rate of dewatering of furnish in the manufacture of paper, and specifically to such a process wherein the pulp constituent of the furnish contains a high content of mechanical and/or thermomechanical pulps.
Description of the Prior Art In the general practice of papermaking, 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.
In general practice, a number of additives are contained in the furnish which is passed to the wire sub-strate (wet web forming means). These additives may include processing aids for improving operation of the papermaking machinery, as well as chemicals for improvement of the properties oE the finished paper product. Suitable pro-cessing aids may include retention aids for the retention oE Eiller additives in and on the resultingly formed web and reduction of loss of paper pulp fincs from the furni~n during the dewatering step and drainage aids for improvir,g the rate of dewatering of the furnish on the wire for~ing means. Other additives may include formation aids, floccu-lants, defoamers, wet and dry strength additives, pitchcontrol agents, slimicides, creping aids, and the like, as is well known to those skilled in the art.
Functional additives may include fillers as men-tioned, sizing aids, strenghtening additives 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.
Based on considerations of efficiency and ease of processing, it is desirable to add drainage aids to the furnish prior to the wet web formation step, to provide in-creased capacity or processing rate in the papermaking pro-cess in systems where dewatering or liquid drainage is the rate-limiting step in the process.
Although it is desirable to maximize drainage rates in the papermkaing system, the additives which here-tofore have been employed for such purpose give rise to low levels of activity when used in newsprint furnishes, which generally are made under strongly acidic and high shear conditions. These include conventional drainage aids contain-ing as anionic substituents -COOH groups, as well as copo-lymeric additives containing -SO3H groups.
As used herein, "newsprint furnish" means a fur-nish for the manufacture of paper and paperboard, particu-larly newsprint, coating raw stock grades and fine paper grades, containing fines and fillers and made under acid conditions, whose pulp constituent comprises at least 40%
by weight of a wood pulp selected from the group consisting of mechanical wood pulp, thermomechanical wood pulp and mixtures thereof.
Accordingly, there is a containing need for im-7 ''i ~
proved dewatering additives for newsprint furnishes char-acterized by stability and high activity It is therefore an object of the present inven-tion to provide a process for increasing rate of dewatering in newsprint Eurnishes at the low pH conditions c'naracter-istic of such furnishes.
SVMMARY OF THE INVENTION
The present invention relates to a process for increasing rate of dewatering in the manufacture of paper from a furnish whose pulp constituent comprises at least 40% by weight of a wood pulp selected from the group con-sisting of mechanical wood pulp, thermomechanical ~ood pulp, and mixtures thereof comprising:
(a) adding to said furnish prior to said dewater-ing thereof (1) from about 0.5 to about 5 percent by weight, based on weight of cellulosic fibers in said furnish, of an aluminum salt, and (2) from about 0.01 to about 0.5 percent by weight, based on weight of cellulosic fibers in said furnish, of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acrylamido-2-methylpropanesulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide; and (b) maintaining pH of said furnish during step (a) and through said dewatering in the range of from about
3.5 to about 6.5.
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a graph of drainage change, i.e., the change in amount of drained liquid, in milliliters, for a Eurnish containing various drainage additives relative to a furnish containing no drainage additives, plotted as a function of furnish pH, for 3% addition of aluminum sulfate (alum) to the furnish.
Fig. 2 is a graph a drainage change, ml, as a function of pH, for 1% alum addition.
Fig. 3 is a graph of drainage change, ml, as a function of alum addition, at pH = 4.5.
Fig. 4 is a graph~of drainage change, ml, as a function of pH, showing parametrically the effect of variant levels of alum addition and of elevated temperature.
DETAILED DESCRIPTION OF THE INVENTIO~l In connection with the present invention, it has surprisingly and unexpectedly been discovered that the use of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acryl-amido-2-methylpropanesulfonic acid (hereinafter denoted as "AMPS"), from O to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide, in combination with addition of an aluminum salt, as for exam-ple aluminum sulfate (alum), aluminum chloride or aluminum nitrate, at low pH conditions on the order of from about 3.5 to about 5.5 is remarkably effective in increasing the rate of dewatering of a furnish whose pulp constituent comprises at least 40 percent by weight of a wood pulp selected from the group consisting of mechanical wood pulp, thermomechanical wood pulp, and mixtures thereof.
The process of the present invention provides high rate and extent of drainage of newsprint furnishes, under strongly acidic conditions, where conventional anion-ic or cationic polymers are not effective. As indicated, conventional drainage aids which contain carboxylic acid groups (and those which contain sulfonic acid groups) are ineffective under such acidic conditions and cationic high molecular weight polymers do not produce adequate effect conditions. Although AMPS polymers and copolymers have been taught as drainage aids in the prior art, e.g., German Offenlegungsschrift 2,248,752, in combination with alum at low pH conditions for treatment of hardwood/softwood kraft pulp furnishes, there has been no recognition that such additives could be used in newsprint-type furnishes as contemplated in the present invention since experience has shown that dewatering aids that work ~ell in bieached pulp furnishes are not effective in groundwood-containing pulps.
In view of the fact that most additives which are satisfac-tory for enhancement of drainage in neutral or alkaline furnish media and kraft pulps are characterized by e~treme-ly poor performance in strongly acidic newsprint-type fur-nishes, it is indeed unexpected that the process of the present invention may be employed to advantage to produce superior levels of drainage.
The AMPS copolymer employed in the present inven-tion contains from about 2 to about 30 mole percent repeat-ing units derived from AMPS, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide. As used herein, AMPS is intended broadly to refer to 2-acrylamido-2-methylpropanesulfonic acid as well as any suitable salts thereof.
Suit.able AMPS copolymers include those containing for example from about 2 to about 20 mole percent repeating units derived from AMPS and from about 80 to about 98 mole percent repeating units derived from acrylamide As used herein, "acrylamide" is intended to be broadly construed to include acrylamide per se as well as acrylamide derivatives, e.g., substituted acrylamides. Such copolymer compositions may be used to particular advantage in furnishes where an aluminum salt, e.g., aluminum sulfate, aluminum nitrate, or aluminum chloride, is added to the furnish in an amount of from about 2 to about 4 percent by weight, based on weight of cellulosic fibers in the furnish. With such weight percent addition of aluminum salt, the pH of the furnish is preferably maintained during the copolymer addition and through the dewatering of the furnish in a range of from about 4.1 to about 6.5.
The aluminum salt is employed in the process of the present invention as a source of polyvalent metal ions, to enhance the effectiveness of the AMPS copolymer and the specific dosage of the aluminum salt which is required in any given system can readily be determined ~lithout Jndue experimentation by simple tests such as Canadian Standard Freeness (CSP) or Britt jar drainage determinations on t'ne furnish which is to be treated. The preferred alumin~m salt is aluminum sulfate (alum).
In systems where the above-described AMPS/acryla-mide copolymer is employed with additions to the furnish of the aluminum salt in the amount of from about 0.5 to about 2 percent by weight, based on weight of cellulosic fibers in the furnish, is satisfactory, it is desirable to maintain pH of the furnish during the copolymer addition and through the dewatering in a range of from about 4.8 to about 6.5, to achieve optimal performance of the drainage additives.
Particularly preferred in the broad practice of the present invention are AMPS copolymers containing from about 2 to about 30 mole percent repeating units derived from AMPS, from about 5 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to 93 mole percent repeating units derived from acrylamide. Such terpolymer system, as discussed hereinaEter in greater detail, has been found to provide particularly enhanced drainage performance when the furnish temperature is main-tained during the terpolymer/aluminum salt addition and through the dewatering in a range of from about 20 to about 60C. Most preferably, enhanced performance has been found to be particularly enhanced at elevated temperatures in the range of from about 40 to about 60C.
The above terpolymer composition has particular utility when the pH of the furnish is maintained during the terpolymer/aluminum salt addition and through the dewatering in a range of from about 4 to about 6.5.
In papermaking systems using the preferred alumi-num salt, aluminum sulfate (alum), where the amount of alum employed for optimum drainage enhancement by the terpolymer is in the range of from about 2 to about 4 percent by weight, based on weight of cellulosic Eibers in the furnish, the pH
of the furnish is desirably maintained through the terpoly-A4~
mer/alum addition and dewatering steps in the range of from about 4.5 to about 6.3. When lower amounts of alum addition are most effective, e.g., in a range of from about 0.5 to about 2 percent by weight addition of alum, based on weight 5 of cellulosic fibers in the furnish, furnish pH is desirably maintained during the terpolymer/alum addition and through the dewatering steps in a range of from about 4.5 to about 5.6. These relationships may vary somewhat for different furnishes, temperature conditions and the presence or absen-ce of recycling in the papermaking system. In practice, the optimum pH conditions can be accurately determined by actual mill trials without undue experimentation.
As indicated, the process of the present invention has particular ut;lity in application to newsprint-type furnishes, whose pulp constituent is mechanical wood pulp and/or thermomechanical wood pulp. Especial utility is realized in application of the process of the invention to stone grou~dwood mechanical pulps.
Preferably, the AMPS copolymer or terpolymer has a molecular weight of from about two million to about twen-ty million. Particularly preferred copolymers may for example have a Standard Brookfield viscosity7 measured in a 0.20 percent solution at 25C. in 0.33 M NaCl with a number one spindle rotating at 60 rpm, of Z-10 centipoises.
Although the present invention in preferred prac-tice employs alum as a source of polyvalent metal cations in the treatment of the furnish with AMPS-containing copoly-mers, it is possible to employ other sources of cationic metal (aluminum) sols having capability to bond with the sulfonic acid groups or carboxylic acid groups as an alter-native to the alum constituent. Other aluminum salts having potential utility in combination with the AMPS co-polymer at low pH conditions include aluminum chloride and aluminum nitrate.
As indicated, heating of the furnish medium, to maintain same at elevated temperature through the AMPS
copolymer/alum addition and dewatering, further improves - ~ -the dewaterability of the furnish7 presumably becau~e ~r~
of the necessary cationic alumina complex forms through olation of aluminum ~ydroxide groups to an Al~-0-Al+ type configuration, which forms at lower pH and is favored by higher stock temperatures.
In the manufacture of newsprint it is of utmost importance to improve drainage or water removal and to mini-mize pitch deposition problems. Both problems can be alle-viated to a great extent by using an appropriate drainage aid which flocculates the groundwood fines as well as retaining the pitch particles on fibers under the strongly acidic conditions characteristic of newsprint furnishes.
Typically, a newsprint furnish will contain approx-imately 25% of long fiber chemical pulp, such as bleached sulfite or bleached kraft and about 75% by weight of high yield mechanical pulps, such as stone groundwood (GW) or a mixture of stone groundwood and thermomechanical (TMP) pulp. Upon forming a sheet (wet-web) on a high spedd com-mercial papermaking machine, much of the fine fibers, con-sisting primarily of the fine fraction of the GW or TMPpulp components, passes through the paper machine wire and characteristically the first pass retention in such systems is low, on the order of about 50-60%. Accordingly, such fines are returned back to the wet-web forming portion of the process system, by recycle of the tray water. By such expedient, the majority of the fines in the initial furnish is finally retained in the sheet after multiple recycles.
High speed paper machines in general are very sen-sitive to any changes in drainage rate and it is most essen-tial to produce flocculation of fines and pitch particles onlong fibers since such flocculation minimizes pitch deposi-tion problems and enhances the rate of water removal. Drain-age aids that perform adequately in fine paper grades gen-erally do not produce perceptible beneficial results in newsprint-type furnishes Such inefficiency may be due to the considerable surface area oÇ the high yield pulps (due to the fines content thereof) and the substantially reduced (inhibited) bonding capacity of the polymeric additive~ on the lignin-rich fiber surfaces of mechanical pulps.
Another factor which precludes the achievement o~
good drainage and high fines retention in ne~sprint-type furnishes is the high hydrodynamic shear of a high speed papermaking machine such as conventionally employed for production of newsprint.
In summary, it has not been possible to translate the performance characteristics of polymeric drainage/re-tention aid additives in fine paper furnishes (see the aforementioned German Offenlegungsschrift 2,248,752, dis-cussed hereinabove) to furnishes containing high percentages of high yield pulps. Accordingly, the present invention representa a substantial advance in the art, in the provi-sion of a furnish treatment (furnish additive) providing a substantial, surprising and wholly unexpected enhancement in the rate of dewatering of furnishes containing signifi-cant content of mechanical wood pulp and/or thermomechanical wood pulp.
The following specific examples illustrate specific aspects of the present invention. These examples are set forth by way of illustration only and are not to be construed as limiting on the scope of the present invention except as set forth in the appended claims. In all examples set forth hereinafter, parts and percentages are by weight unless otherwise specified.
E~AMPI.E I
A laboratory drainage test procedure was developed, for use in the examples which follow. It is typically very difficult to obtain accurate measurements of drainage chan-ges in high groundwood content pulps, due to the slow drain-ing character of such pulps. As indicated, the composition of typical commercial newsprint furnishes is approximately 75~/o by weight groundwood and 25~o by weight chemical long fiber pulps. For the measurements carried out in the sub-sequent examples, the furnish was 5()~:50~ I>y wei~ht Or each fiber component, i.e., groundwood and chemical lorlg fi3er pulp. The long fiber pulp portion of the furnish consi~ted of equal parts of~bleached softwood and hard~ood kraft that had been beated to about 450 CS~. The groundwood portion of this experimental Eurnish represented a typical stone groundwood, produced for newsprint production by Bowaters Paper Company, Calhoun, Tennessee, at a pH of 4.7 and con-taining about 1.0 percent by weight of alum, based on the weight of fibers, the alum being added during the ground-wood production to reduce pitch deposition in the subsequentpapermaking operation.
In each of the tests described hereinafter, the 50:50 percent by weight mixture of the chemical long fiber pulp and groundwood pulp was diluted to 0.5 percent fiber consistency and treated with addition alum, to carry out the process of the present invention, with the pH of such furnish being adjusted by addition of dilute sodium hydrox-ide to the furnish.
To the furnish stock prepared as described above was added a 0.1% solution of the specific polymer or co-polymer drainage additive at a dosage level of 0.025% actual polymer based on total fiber weight. This furnish then was mixed by transferring same from one container to ano-ther for six times. A 500 milliliter (ml) aliquot of the treated furnish then was transferred into a drainage tube, equipped with paper machine wire at the bottom end. The furnish was allowed to drain for fifteen seconds and the filtrate co]lected during such period of time was quanti-tatively measured. ~ large increase in the amount of filtrate during a given run relative to the control fur-nish containing no drainage aid is indicative of signi-ficantly improved water release or drainage by the forming web.
In each experiment in the examples to follow, a blank test run was made wherein the furnish contained no additives, other than alum. An increase or a decrease in the amount of collected filtrate, as compared to the ~ 3.
blank, is indicative of an increase or a decrea~e, re~pec-tively, in the rate oE drainage of the furnish.
In the evaluations of the process of the present invention for newsprint manufacture, a typical cationic and a typical anionic polyacrylamide retention/drainage aid ~as included in separate drainage tes~ runs for compari~on.
These conventional cationic and anionic polyacrylamide ad-ditives had molecular weights in the range of 4-15 million.
EXAMPLE II
Figure I is a graph of draingae change, i.e., the change in amount of drained liquid, in milliliters (ml), for a furnish containing various drainage additives relative to a furnish containing no additives (blank), as a function of furnish pH, for 3% addition of alum to the furnish. In Figure I, curve A is the drainage curve for the above-des-cribed furnish, containing as the drainage aid a copolymercontaining 15% by weight AMPS and 85% by weight acrylamide (AM~. Curve B is the drainge curve for a furnish contain-ing 5% by weight AMPS, 10% by weight acrylic acid (AA) and 85% by weight AM. Curve C represents the drainage perform~
ance of a furnish containing the aforementioned convention-al anionic polyacrylamide drainage/retention agent, and Curve D is the performance curve for a furnish containing the conventional cationic polyacrylamide drainage/retention agent previously described.
As is seen from ~igure I that changes in pH dra-matically effect the performance of all the furnish compo-sitions tested, particularly the highly anionic A~PS co-polymers (Curves A and B) and the anionic polyacrylamide furnish (Curve C). The 15/85 AMPS/AM copolymer (Curve A) produces the best drainage in the pH range oE 4.3 to 5.7 of all furnishes tested, while the anionic (carboxyl group-containing) polyacrylamide is relatively unaEEected by change of pH in this range. The cationic polyacrylamide (Curve D) has a moderate effect in this pH range. Such pH
range and alum dosage (3% by weight) generally is repre-sentative of process conditions in numerous ner"sprin~ mills With both the AMPS copolymer of Curve A and the A~PS ter-polymer of Curve B, the alum added to the finish should be partially neutralized, i.e., in the form oE a polymer of cationic alumina. Since excessive Elocculation may be un-desirable in a given application, the best composition, as between a copolymer of the type represented by Curve A and a terpolymer of the type represented by Curve B may be de-termined by actual mill trial, as indicated hereinabove.
Nonetheless, as clearly shown by the graph, either type of AMPS-containing polymer is more effective than the cat-ionic polyacrylamide (Curve D) heretofore used as a conven-tional drainage/retention aid.
The anionic polyacrylamide of Curve C becomes highly active only at high pH where the polymer is more structurall~ extended. High pH conditions, however, are not attractive in newsprint manufacture because of pitch deposition problems associated therewith. On the other hand, if the pH is reduced to extremely low levels, on the order of less than 4.0, the AMPS-containing polymers become significantly less effective, presumably due to the absence of adequate amounts of cationic polymeric alumina which probably provides activated bonding sites for such polymers.
EXAMPLE III
Figure II is a graph of drainage change, ml, as a function of pH, for one percent by weight alum addition to the furnish. The various curves correspond to the same furnish compositions and drainage aids as the corresponding-ly lettered curves of Figure I.
As seen from the graph, the AM~S-containing co-polymers become highly effective when the pH of the furnish is increased to a point (approximately 5-5.5) where as suf-ficient amount of cationic polymeric alumina is for~ed.
The observed shift in optimum pH, as comapred to the results in Example II is probably due to the lower alum dosage level in this instance relative to Example II, which de-creases the erfective concentration or the active cationic alumina. The results shown in Figure II indicate that ,h~
optimum operating pH is a function of the available cation-ic alumina (cationic polymeric Al ions) in the furnisn.
EXAMPLE IV
Figure III is a graph of drainage change, ml, as a function of alum addition, at a pH of 4.5. Curve A re-fers to a furnish containing as the drainage aid a 15 weight percent/85 weight percent AMPS/AM copolymer; Curve B refers to a furnish containing a 5:15:80 weight percent AMPS/AA/A~D
terpolymer; and Curve C refers to a furnish employing as the drainage aid an anionic polyacrylamide containing 30 percent free carboxyl groups.
In this experiment, the dosage of alum was varied from 0.5% to 2.0% by weight based on the weight of fibers present in the furnish and pH was controlled at ~.5. The results obtained are cons-istent with the results shown in Example III in demonstrating at low alum levels (e.g., 0.5 1.0% by weight) the polymer may actually retard drainage.
In this furnish system, a minimum of 1.5-2.0% by weight appears to be essential for adequate activation of the AMPS--containing polymers. The carboxyl group-containing anionic polyacrylamide is unaffected by change in the alum content of the furnish.
EXAMPLE V
Figure IV is a graph of drainage change, ml, as a function of pH, showing parametrically the effect of variant levels of alum addition and of elevated temperature.
The effect of temperature on the drainage rate to determine whether heat would affect the alum chemistry by favoring formation of o~olated (polymeric) species of alumina at in-creased temperature.
The parametric alum concentration and temperature conditions are set forth on the draft. The drainage aid employed in all instances was a terpolymer of 5/15/~0 weight percent AMPS/AA/AM.
In each run, the furnish was adjusted to the spe-cific temperature by warming a stainless steel beaker con-taining the furnish in a steam bath. Once the parametric temperature condition was realized, the furnish was treated with alum and neutralized with an appropriate amount ot 5 sodium hydroxide and allowed to equilibrate for five min-utes.
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a graph of drainage change, i.e., the change in amount of drained liquid, in milliliters, for a Eurnish containing various drainage additives relative to a furnish containing no drainage additives, plotted as a function of furnish pH, for 3% addition of aluminum sulfate (alum) to the furnish.
Fig. 2 is a graph a drainage change, ml, as a function of pH, for 1% alum addition.
Fig. 3 is a graph of drainage change, ml, as a function of alum addition, at pH = 4.5.
Fig. 4 is a graph~of drainage change, ml, as a function of pH, showing parametrically the effect of variant levels of alum addition and of elevated temperature.
DETAILED DESCRIPTION OF THE INVENTIO~l In connection with the present invention, it has surprisingly and unexpectedly been discovered that the use of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units derived from 2-acryl-amido-2-methylpropanesulfonic acid (hereinafter denoted as "AMPS"), from O to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide, in combination with addition of an aluminum salt, as for exam-ple aluminum sulfate (alum), aluminum chloride or aluminum nitrate, at low pH conditions on the order of from about 3.5 to about 5.5 is remarkably effective in increasing the rate of dewatering of a furnish whose pulp constituent comprises at least 40 percent by weight of a wood pulp selected from the group consisting of mechanical wood pulp, thermomechanical wood pulp, and mixtures thereof.
The process of the present invention provides high rate and extent of drainage of newsprint furnishes, under strongly acidic conditions, where conventional anion-ic or cationic polymers are not effective. As indicated, conventional drainage aids which contain carboxylic acid groups (and those which contain sulfonic acid groups) are ineffective under such acidic conditions and cationic high molecular weight polymers do not produce adequate effect conditions. Although AMPS polymers and copolymers have been taught as drainage aids in the prior art, e.g., German Offenlegungsschrift 2,248,752, in combination with alum at low pH conditions for treatment of hardwood/softwood kraft pulp furnishes, there has been no recognition that such additives could be used in newsprint-type furnishes as contemplated in the present invention since experience has shown that dewatering aids that work ~ell in bieached pulp furnishes are not effective in groundwood-containing pulps.
In view of the fact that most additives which are satisfac-tory for enhancement of drainage in neutral or alkaline furnish media and kraft pulps are characterized by e~treme-ly poor performance in strongly acidic newsprint-type fur-nishes, it is indeed unexpected that the process of the present invention may be employed to advantage to produce superior levels of drainage.
The AMPS copolymer employed in the present inven-tion contains from about 2 to about 30 mole percent repeat-ing units derived from AMPS, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating units derived from acrylamide. As used herein, AMPS is intended broadly to refer to 2-acrylamido-2-methylpropanesulfonic acid as well as any suitable salts thereof.
Suit.able AMPS copolymers include those containing for example from about 2 to about 20 mole percent repeating units derived from AMPS and from about 80 to about 98 mole percent repeating units derived from acrylamide As used herein, "acrylamide" is intended to be broadly construed to include acrylamide per se as well as acrylamide derivatives, e.g., substituted acrylamides. Such copolymer compositions may be used to particular advantage in furnishes where an aluminum salt, e.g., aluminum sulfate, aluminum nitrate, or aluminum chloride, is added to the furnish in an amount of from about 2 to about 4 percent by weight, based on weight of cellulosic fibers in the furnish. With such weight percent addition of aluminum salt, the pH of the furnish is preferably maintained during the copolymer addition and through the dewatering of the furnish in a range of from about 4.1 to about 6.5.
The aluminum salt is employed in the process of the present invention as a source of polyvalent metal ions, to enhance the effectiveness of the AMPS copolymer and the specific dosage of the aluminum salt which is required in any given system can readily be determined ~lithout Jndue experimentation by simple tests such as Canadian Standard Freeness (CSP) or Britt jar drainage determinations on t'ne furnish which is to be treated. The preferred alumin~m salt is aluminum sulfate (alum).
In systems where the above-described AMPS/acryla-mide copolymer is employed with additions to the furnish of the aluminum salt in the amount of from about 0.5 to about 2 percent by weight, based on weight of cellulosic fibers in the furnish, is satisfactory, it is desirable to maintain pH of the furnish during the copolymer addition and through the dewatering in a range of from about 4.8 to about 6.5, to achieve optimal performance of the drainage additives.
Particularly preferred in the broad practice of the present invention are AMPS copolymers containing from about 2 to about 30 mole percent repeating units derived from AMPS, from about 5 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to 93 mole percent repeating units derived from acrylamide. Such terpolymer system, as discussed hereinaEter in greater detail, has been found to provide particularly enhanced drainage performance when the furnish temperature is main-tained during the terpolymer/aluminum salt addition and through the dewatering in a range of from about 20 to about 60C. Most preferably, enhanced performance has been found to be particularly enhanced at elevated temperatures in the range of from about 40 to about 60C.
The above terpolymer composition has particular utility when the pH of the furnish is maintained during the terpolymer/aluminum salt addition and through the dewatering in a range of from about 4 to about 6.5.
In papermaking systems using the preferred alumi-num salt, aluminum sulfate (alum), where the amount of alum employed for optimum drainage enhancement by the terpolymer is in the range of from about 2 to about 4 percent by weight, based on weight of cellulosic Eibers in the furnish, the pH
of the furnish is desirably maintained through the terpoly-A4~
mer/alum addition and dewatering steps in the range of from about 4.5 to about 6.3. When lower amounts of alum addition are most effective, e.g., in a range of from about 0.5 to about 2 percent by weight addition of alum, based on weight 5 of cellulosic fibers in the furnish, furnish pH is desirably maintained during the terpolymer/alum addition and through the dewatering steps in a range of from about 4.5 to about 5.6. These relationships may vary somewhat for different furnishes, temperature conditions and the presence or absen-ce of recycling in the papermaking system. In practice, the optimum pH conditions can be accurately determined by actual mill trials without undue experimentation.
As indicated, the process of the present invention has particular ut;lity in application to newsprint-type furnishes, whose pulp constituent is mechanical wood pulp and/or thermomechanical wood pulp. Especial utility is realized in application of the process of the invention to stone grou~dwood mechanical pulps.
Preferably, the AMPS copolymer or terpolymer has a molecular weight of from about two million to about twen-ty million. Particularly preferred copolymers may for example have a Standard Brookfield viscosity7 measured in a 0.20 percent solution at 25C. in 0.33 M NaCl with a number one spindle rotating at 60 rpm, of Z-10 centipoises.
Although the present invention in preferred prac-tice employs alum as a source of polyvalent metal cations in the treatment of the furnish with AMPS-containing copoly-mers, it is possible to employ other sources of cationic metal (aluminum) sols having capability to bond with the sulfonic acid groups or carboxylic acid groups as an alter-native to the alum constituent. Other aluminum salts having potential utility in combination with the AMPS co-polymer at low pH conditions include aluminum chloride and aluminum nitrate.
As indicated, heating of the furnish medium, to maintain same at elevated temperature through the AMPS
copolymer/alum addition and dewatering, further improves - ~ -the dewaterability of the furnish7 presumably becau~e ~r~
of the necessary cationic alumina complex forms through olation of aluminum ~ydroxide groups to an Al~-0-Al+ type configuration, which forms at lower pH and is favored by higher stock temperatures.
In the manufacture of newsprint it is of utmost importance to improve drainage or water removal and to mini-mize pitch deposition problems. Both problems can be alle-viated to a great extent by using an appropriate drainage aid which flocculates the groundwood fines as well as retaining the pitch particles on fibers under the strongly acidic conditions characteristic of newsprint furnishes.
Typically, a newsprint furnish will contain approx-imately 25% of long fiber chemical pulp, such as bleached sulfite or bleached kraft and about 75% by weight of high yield mechanical pulps, such as stone groundwood (GW) or a mixture of stone groundwood and thermomechanical (TMP) pulp. Upon forming a sheet (wet-web) on a high spedd com-mercial papermaking machine, much of the fine fibers, con-sisting primarily of the fine fraction of the GW or TMPpulp components, passes through the paper machine wire and characteristically the first pass retention in such systems is low, on the order of about 50-60%. Accordingly, such fines are returned back to the wet-web forming portion of the process system, by recycle of the tray water. By such expedient, the majority of the fines in the initial furnish is finally retained in the sheet after multiple recycles.
High speed paper machines in general are very sen-sitive to any changes in drainage rate and it is most essen-tial to produce flocculation of fines and pitch particles onlong fibers since such flocculation minimizes pitch deposi-tion problems and enhances the rate of water removal. Drain-age aids that perform adequately in fine paper grades gen-erally do not produce perceptible beneficial results in newsprint-type furnishes Such inefficiency may be due to the considerable surface area oÇ the high yield pulps (due to the fines content thereof) and the substantially reduced (inhibited) bonding capacity of the polymeric additive~ on the lignin-rich fiber surfaces of mechanical pulps.
Another factor which precludes the achievement o~
good drainage and high fines retention in ne~sprint-type furnishes is the high hydrodynamic shear of a high speed papermaking machine such as conventionally employed for production of newsprint.
In summary, it has not been possible to translate the performance characteristics of polymeric drainage/re-tention aid additives in fine paper furnishes (see the aforementioned German Offenlegungsschrift 2,248,752, dis-cussed hereinabove) to furnishes containing high percentages of high yield pulps. Accordingly, the present invention representa a substantial advance in the art, in the provi-sion of a furnish treatment (furnish additive) providing a substantial, surprising and wholly unexpected enhancement in the rate of dewatering of furnishes containing signifi-cant content of mechanical wood pulp and/or thermomechanical wood pulp.
The following specific examples illustrate specific aspects of the present invention. These examples are set forth by way of illustration only and are not to be construed as limiting on the scope of the present invention except as set forth in the appended claims. In all examples set forth hereinafter, parts and percentages are by weight unless otherwise specified.
E~AMPI.E I
A laboratory drainage test procedure was developed, for use in the examples which follow. It is typically very difficult to obtain accurate measurements of drainage chan-ges in high groundwood content pulps, due to the slow drain-ing character of such pulps. As indicated, the composition of typical commercial newsprint furnishes is approximately 75~/o by weight groundwood and 25~o by weight chemical long fiber pulps. For the measurements carried out in the sub-sequent examples, the furnish was 5()~:50~ I>y wei~ht Or each fiber component, i.e., groundwood and chemical lorlg fi3er pulp. The long fiber pulp portion of the furnish consi~ted of equal parts of~bleached softwood and hard~ood kraft that had been beated to about 450 CS~. The groundwood portion of this experimental Eurnish represented a typical stone groundwood, produced for newsprint production by Bowaters Paper Company, Calhoun, Tennessee, at a pH of 4.7 and con-taining about 1.0 percent by weight of alum, based on the weight of fibers, the alum being added during the ground-wood production to reduce pitch deposition in the subsequentpapermaking operation.
In each of the tests described hereinafter, the 50:50 percent by weight mixture of the chemical long fiber pulp and groundwood pulp was diluted to 0.5 percent fiber consistency and treated with addition alum, to carry out the process of the present invention, with the pH of such furnish being adjusted by addition of dilute sodium hydrox-ide to the furnish.
To the furnish stock prepared as described above was added a 0.1% solution of the specific polymer or co-polymer drainage additive at a dosage level of 0.025% actual polymer based on total fiber weight. This furnish then was mixed by transferring same from one container to ano-ther for six times. A 500 milliliter (ml) aliquot of the treated furnish then was transferred into a drainage tube, equipped with paper machine wire at the bottom end. The furnish was allowed to drain for fifteen seconds and the filtrate co]lected during such period of time was quanti-tatively measured. ~ large increase in the amount of filtrate during a given run relative to the control fur-nish containing no drainage aid is indicative of signi-ficantly improved water release or drainage by the forming web.
In each experiment in the examples to follow, a blank test run was made wherein the furnish contained no additives, other than alum. An increase or a decrease in the amount of collected filtrate, as compared to the ~ 3.
blank, is indicative of an increase or a decrea~e, re~pec-tively, in the rate oE drainage of the furnish.
In the evaluations of the process of the present invention for newsprint manufacture, a typical cationic and a typical anionic polyacrylamide retention/drainage aid ~as included in separate drainage tes~ runs for compari~on.
These conventional cationic and anionic polyacrylamide ad-ditives had molecular weights in the range of 4-15 million.
EXAMPLE II
Figure I is a graph of draingae change, i.e., the change in amount of drained liquid, in milliliters (ml), for a furnish containing various drainage additives relative to a furnish containing no additives (blank), as a function of furnish pH, for 3% addition of alum to the furnish. In Figure I, curve A is the drainage curve for the above-des-cribed furnish, containing as the drainage aid a copolymercontaining 15% by weight AMPS and 85% by weight acrylamide (AM~. Curve B is the drainge curve for a furnish contain-ing 5% by weight AMPS, 10% by weight acrylic acid (AA) and 85% by weight AM. Curve C represents the drainage perform~
ance of a furnish containing the aforementioned convention-al anionic polyacrylamide drainage/retention agent, and Curve D is the performance curve for a furnish containing the conventional cationic polyacrylamide drainage/retention agent previously described.
As is seen from ~igure I that changes in pH dra-matically effect the performance of all the furnish compo-sitions tested, particularly the highly anionic A~PS co-polymers (Curves A and B) and the anionic polyacrylamide furnish (Curve C). The 15/85 AMPS/AM copolymer (Curve A) produces the best drainage in the pH range oE 4.3 to 5.7 of all furnishes tested, while the anionic (carboxyl group-containing) polyacrylamide is relatively unaEEected by change of pH in this range. The cationic polyacrylamide (Curve D) has a moderate effect in this pH range. Such pH
range and alum dosage (3% by weight) generally is repre-sentative of process conditions in numerous ner"sprin~ mills With both the AMPS copolymer of Curve A and the A~PS ter-polymer of Curve B, the alum added to the finish should be partially neutralized, i.e., in the form oE a polymer of cationic alumina. Since excessive Elocculation may be un-desirable in a given application, the best composition, as between a copolymer of the type represented by Curve A and a terpolymer of the type represented by Curve B may be de-termined by actual mill trial, as indicated hereinabove.
Nonetheless, as clearly shown by the graph, either type of AMPS-containing polymer is more effective than the cat-ionic polyacrylamide (Curve D) heretofore used as a conven-tional drainage/retention aid.
The anionic polyacrylamide of Curve C becomes highly active only at high pH where the polymer is more structurall~ extended. High pH conditions, however, are not attractive in newsprint manufacture because of pitch deposition problems associated therewith. On the other hand, if the pH is reduced to extremely low levels, on the order of less than 4.0, the AMPS-containing polymers become significantly less effective, presumably due to the absence of adequate amounts of cationic polymeric alumina which probably provides activated bonding sites for such polymers.
EXAMPLE III
Figure II is a graph of drainage change, ml, as a function of pH, for one percent by weight alum addition to the furnish. The various curves correspond to the same furnish compositions and drainage aids as the corresponding-ly lettered curves of Figure I.
As seen from the graph, the AM~S-containing co-polymers become highly effective when the pH of the furnish is increased to a point (approximately 5-5.5) where as suf-ficient amount of cationic polymeric alumina is for~ed.
The observed shift in optimum pH, as comapred to the results in Example II is probably due to the lower alum dosage level in this instance relative to Example II, which de-creases the erfective concentration or the active cationic alumina. The results shown in Figure II indicate that ,h~
optimum operating pH is a function of the available cation-ic alumina (cationic polymeric Al ions) in the furnisn.
EXAMPLE IV
Figure III is a graph of drainage change, ml, as a function of alum addition, at a pH of 4.5. Curve A re-fers to a furnish containing as the drainage aid a 15 weight percent/85 weight percent AMPS/AM copolymer; Curve B refers to a furnish containing a 5:15:80 weight percent AMPS/AA/A~D
terpolymer; and Curve C refers to a furnish employing as the drainage aid an anionic polyacrylamide containing 30 percent free carboxyl groups.
In this experiment, the dosage of alum was varied from 0.5% to 2.0% by weight based on the weight of fibers present in the furnish and pH was controlled at ~.5. The results obtained are cons-istent with the results shown in Example III in demonstrating at low alum levels (e.g., 0.5 1.0% by weight) the polymer may actually retard drainage.
In this furnish system, a minimum of 1.5-2.0% by weight appears to be essential for adequate activation of the AMPS--containing polymers. The carboxyl group-containing anionic polyacrylamide is unaffected by change in the alum content of the furnish.
EXAMPLE V
Figure IV is a graph of drainage change, ml, as a function of pH, showing parametrically the effect of variant levels of alum addition and of elevated temperature.
The effect of temperature on the drainage rate to determine whether heat would affect the alum chemistry by favoring formation of o~olated (polymeric) species of alumina at in-creased temperature.
The parametric alum concentration and temperature conditions are set forth on the draft. The drainage aid employed in all instances was a terpolymer of 5/15/~0 weight percent AMPS/AA/AM.
In each run, the furnish was adjusted to the spe-cific temperature by warming a stainless steel beaker con-taining the furnish in a steam bath. Once the parametric temperature condition was realized, the furnish was treated with alum and neutralized with an appropriate amount ot 5 sodium hydroxide and allowed to equilibrate for five min-utes.
Claims (10)
1. A process for increasing rate of dewatering in the manufacture of paper from a furnish whose pulp con-stituent comprises at least 40% by weight of a wood pulp selected from the group consisting of mechanical wood pulp, thermomechanical wood pulp, and mixtures thereof, compri-sing:
(a) adding to said furnish prior to said dewatering thereof (1) from about 0.5 to about 5 percent by weight, based on weight of cellulosic fibers in said fur-nish, of an aluminum salt, and (2) from about 0.01 to about 0.5 percent by weight, based on weight of cellulosic fibers in said furnish, of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units de-rived from 2-acrylamido-2-methylpropanesulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating untis derived from acrylamide; and (b) maintaining pH of said furnish during step (a) and through said dewatering in the range of from about 3.5 to about 6.5.
(a) adding to said furnish prior to said dewatering thereof (1) from about 0.5 to about 5 percent by weight, based on weight of cellulosic fibers in said fur-nish, of an aluminum salt, and (2) from about 0.01 to about 0.5 percent by weight, based on weight of cellulosic fibers in said furnish, of a water-soluble copolymer containing from about 2 to about 30 mole percent repeating units de-rived from 2-acrylamido-2-methylpropanesulfonic acid, from 0 to about 25 mole percent repeating units derived from acrylic acid, and from about 45 to about 98 mole percent repeating untis derived from acrylamide; and (b) maintaining pH of said furnish during step (a) and through said dewatering in the range of from about 3.5 to about 6.5.
2. A process according to Claim 1 wherein said copolymer contains from about 2 to about 20 mole percent repeating units derived from 2-acrylamido-2-methylpropane-sulfonic acid and from about 80 to about 98 mole percent repeating units derived from acrylamide.
3. A process according to Claim 2 wherein the addition of said aluminum salt to said furnish is in an amount of from about 2 to about 4 percent by weight, based on weight of cellulosic fibers in said furnish.
4. A process according to Claim 3 wherein pH of said furnish is maintained during step (a) and through said dewatering in the range of from about 4.1 to about 6.5.
5. A process according to Claim 2 wherein the addition of said aluminum salt to said furnish is in an amount of from about 0.5 to about 2 percent by weight, based on weight of cellulosic fibers in said furnish.
6. A process according to Claim 4 wherein pH of said furnish is maintained during step (a) and through said dewatering in the range of from about 4.8 to about 6.5.
7. A process according to Claim 1 wherein said copolymer contains from about 2 to about 30 mole percent repeating units derived from 2-acrylamido-2-methylpropane-sulfonic acid, from about 5 to about 25 mole percent repeat ing units derived from acrylic acid, and from about 45 to about 93 mole percent repeating units derived from acryl-amide.
8. A process according to Claim 6 wherein pH of said furnish is maintained during step (a) and through said dewatering in the range of from about 4 to about 6.5.
9. A process according to Claim 1, further com-prising maintaining temperature of said furnish during step (a) and through said dewatering in the range of from about 20 to about 60°C.
10. A process according to Claim 6, further com-prising maintaining temperature of said furnish during step (a) and through said dewatering in the range of from about 40 to about 60°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50456183A | 1983-06-15 | 1983-06-15 | |
| US504,561 | 1983-06-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1216711A true CA1216711A (en) | 1987-01-20 |
Family
ID=24006797
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000456437A Expired CA1216711A (en) | 1983-06-15 | 1984-06-13 | Manufacture of paper using copolymers of 2-acrylamido- 2-methylpropane sulfonic acid for increasing rate of dewatering of high mechanical/themomechanical pulp furnishes |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0129078B1 (en) |
| JP (1) | JPS6017192A (en) |
| KR (1) | KR900002108B1 (en) |
| AT (1) | ATE31757T1 (en) |
| AU (1) | AU2936284A (en) |
| CA (1) | CA1216711A (en) |
| DE (1) | DE3468458D1 (en) |
| DK (1) | DK291684A (en) |
| FI (1) | FI71799C (en) |
| NO (1) | NO842387L (en) |
| ZA (1) | ZA844518B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019048587A1 (en) * | 2017-09-08 | 2019-03-14 | Basf Se | Composition comprising cross-linked anionic, organic polymeric microparticles, its preparation and use in paper and paperboard making processes |
| US20240066474A1 (en) * | 2022-08-30 | 2024-02-29 | Saudi Arabian Oil Company | Static mixer for electrical submersible pump (esp) high gas/oil ratio (gor) completions |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE789727A (en) * | 1971-10-06 | 1973-04-05 | Calgon Corp | WATER-SOLUBLE POLYMERS OF 2-ACYLAMIDO-2-METHYLPROPANE SULPHONIC ACID |
-
1984
- 1984-05-18 AT AT84105686T patent/ATE31757T1/en not_active IP Right Cessation
- 1984-05-18 DE DE8484105686T patent/DE3468458D1/en not_active Expired
- 1984-05-18 EP EP84105686A patent/EP0129078B1/en not_active Expired
- 1984-06-12 JP JP59119232A patent/JPS6017192A/en active Pending
- 1984-06-13 CA CA000456437A patent/CA1216711A/en not_active Expired
- 1984-06-14 AU AU29362/84A patent/AU2936284A/en not_active Abandoned
- 1984-06-14 KR KR1019840003336A patent/KR900002108B1/en active IP Right Grant
- 1984-06-14 NO NO842387A patent/NO842387L/en unknown
- 1984-06-14 DK DK291684A patent/DK291684A/en not_active Application Discontinuation
- 1984-06-14 FI FI842418A patent/FI71799C/en not_active IP Right Cessation
- 1984-06-14 ZA ZA844518A patent/ZA844518B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DK291684D0 (en) | 1984-06-14 |
| FI71799C (en) | 1987-02-09 |
| ATE31757T1 (en) | 1988-01-15 |
| FI842418A (en) | 1984-12-16 |
| ZA844518B (en) | 1985-02-27 |
| NO842387L (en) | 1984-12-17 |
| JPS6017192A (en) | 1985-01-29 |
| EP0129078B1 (en) | 1988-01-07 |
| KR850000564A (en) | 1985-02-28 |
| EP0129078A1 (en) | 1984-12-27 |
| DE3468458D1 (en) | 1988-02-11 |
| FI71799B (en) | 1986-10-31 |
| FI842418A0 (en) | 1984-06-14 |
| KR900002108B1 (en) | 1990-04-02 |
| AU2936284A (en) | 1984-12-20 |
| DK291684A (en) | 1984-12-16 |
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