CA2334196C - Method for making paper and cardboard and retention and dewatering agents - Google Patents
Method for making paper and cardboard and retention and dewatering agents Download PDFInfo
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- CA2334196C CA2334196C CA002334196A CA2334196A CA2334196C CA 2334196 C CA2334196 C CA 2334196C CA 002334196 A CA002334196 A CA 002334196A CA 2334196 A CA2334196 A CA 2334196A CA 2334196 C CA2334196 C CA 2334196C
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- polymer
- branched
- emulsion
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- reverse phase
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Classifications
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- 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
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
- D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
- D21H23/06—Controlling the addition
- D21H23/14—Controlling the addition by selecting point of addition or time of contact between components
-
- 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
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
- D21H23/765—Addition of all compounds to the 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
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
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Abstract
The invention concerns an improved method for making paper which consists in using as main retention agent a branched polymer prepared in invert emulsion and bentonite as secondary retention agent (dual type system). The two additions are separated by a step for shearing the fibrous suspension (or mass). The invention enables to obtain a highly improved retention and also highly improved dewatering.
Moreover, it enables to reduce the bentonite content in the white water.
Moreover, it enables to reduce the bentonite content in the white water.
Description
METHOD FOR MAKING PAPER AND CARDBOARD AND RETENTION AND
DEWATERING AGENTS
The present invention relates to the technical field of paper production and the polymers used in this field.
The invention relates to a process for producing a paper or paperboard with improved retention and other properties.
During the production of paper, paperboard, or the like, it is well known to introduce into the pulp retention aids whose function is to retain a maximum of fines and fillers in the sheet. The beneficial effects that result from the utilization of a retention aid are essentially:
- increased production and reduction of production costs: energy savings, more reliable operation of the machine, higher yield in terms of fibers, fines, fillers and anionic finishing products, lower acidity in the circuit linked to a decrease in the use of aluminum sulfate, and hence a reduction in corrosion problems;
- an improvement in quality: better formation and better look-through, an improvement in the moisture content, the opacity, the gloss, and the absorptive capacity of the sheet, and a reduction in the porosity of the paper.
Long ago, it was proposed that bentonite be added to the pulp, possibly together with other mineral products such as aluminum sulfates or even synthetic polymers, notably polyethylene imine (see for example the documents DE-A-2 262 906 and US-A-2 308 635).
In the document US-A-3 052 595, it was proposed to associate the bentonite with a polyacrylamide of an essentially linear
DEWATERING AGENTS
The present invention relates to the technical field of paper production and the polymers used in this field.
The invention relates to a process for producing a paper or paperboard with improved retention and other properties.
During the production of paper, paperboard, or the like, it is well known to introduce into the pulp retention aids whose function is to retain a maximum of fines and fillers in the sheet. The beneficial effects that result from the utilization of a retention aid are essentially:
- increased production and reduction of production costs: energy savings, more reliable operation of the machine, higher yield in terms of fibers, fines, fillers and anionic finishing products, lower acidity in the circuit linked to a decrease in the use of aluminum sulfate, and hence a reduction in corrosion problems;
- an improvement in quality: better formation and better look-through, an improvement in the moisture content, the opacity, the gloss, and the absorptive capacity of the sheet, and a reduction in the porosity of the paper.
Long ago, it was proposed that bentonite be added to the pulp, possibly together with other mineral products such as aluminum sulfates or even synthetic polymers, notably polyethylene imine (see for example the documents DE-A-2 262 906 and US-A-2 308 635).
In the document US-A-3 052 595, it was proposed to associate the bentonite with a polyacrylamide of an essentially linear
2 nature. Th:s process met with competition from systems that were easier to i.se yet performed just as well. Moreover, even with the current lii.ear polyacrylamides, the retention capacity is still insufficiei.t .
In thE document EP-A-0 017 353, it was proposed, for the retention cf low-filler pulps (less than 5jk fillers), to associate the bentonite with a nonionic to slightly anionic linear copclyacrylamide. This process has not been very widely used, sincE these polymers perform relatively poorly in terms of retention, especially that of pulps containing fillers, no doubt as a result of inaufficient synergy between these copolymers and bentonite, which does not have much of a tendency to recoagulate.
1.5 In the document EP-A-0-235 893, it was proposed to use essentiall} linear cationic polyacrylamides having molecular weights of greater than one million, of thirty million and higher. This resulte in the obtainment-of a retention effect that is satisfactory, but is still deemed inadequate in the papermaking application; since the use of bentonite causes problems during the subsequent treatment of the effluents issuing from the ma::hine, users select this system on].y if there are significant advantages.
In the notes presented at the lecture given in Seattle on October 11-L3, 1989, published under the title "Supercoagulation in the cont:ol of wet end chemistry by synthetic polymer and activated b;ntonite," R. Rajasvixta described the mechanism of -supercoagulition of activated bentonite in the presencd of a cationic po_yacrylamide, without specifying its exact nature.
This proces, has the same drawbacks as above.
Lastly European Patent 0 574 335 produced an impox-tant improvement by proposing the use branched polymers (particularly polyacrylam,des) in powder form.
The invention eliminates the drawbacks mentioned above.
According to one aspect of the invention, there is provided a process for manufacturing a sheet of paper or paperboard having improved retention and drainage properties, of the type which uses a dual system of an acrylic polymer and bentonite or a possibly treated kaolin as the primary and secondary retention agents, respectively, the introductions of which are separated by a stage for shearing the suspension or fibrous mass or paper pulp, characterized in that said polymer is a branched acrylic (co)polymer prepared in the form of a reverse phase water-in-oil emulsion, used either in emulsion reversed in water or in a solution of the powder obtained by drying the emulsion, said branched acrylic (co)polymer being introduced into the paper pulp at a concentration of 0.03 to one per mill (0.03 to 1 %o) by weight or 30 to 1,000 g/t, of the dry weight of the fibrous suspension of paper pulp, wherein its UL viscosity is > 3.
Its object is to obtain an improved process of the type in question, which is comprised of adding to the suspension or fibrous mass or paper pulp to be flocculated, as the main retention aid, an agent consisting of or comprising a branched polyacrylamide which is characterized in that it has been prepared in reverse phase or water-in-oil emulsion, and bentonite as the second retention aid (a so-called "dual" system of the type also known as "microparticulate").
The phrase "exists in reverse phase emulsion" or similar expressions related to the polymer used (i.e., injected or introduced into the pulp to be flocculated) according to the invention, will be understood by one skilled in the art to designate the reverse phase water-in-oil emulsion that is dissolved in water before its injection or its introduction into the mass or pulp to be flocculated (this dissolution in water results in what is known as the "reversal" of the initial reverse phase water-in-oil emulsion; these processes are well known to 85750-14 3a one skilled in the art).
The additions of the polymer and the bentonite are separated by a shearing stage, for example at the level of the mixing pump known as a "fan pump." In this field, the reader is referred to the specification of US patent 4,753,710, as well as to a vast body of prior art related to the addition point of the retention aid relative to the shearing stages existing in the machine, including US patent 3,052,595; Unbehend, TAPPI Vol. 59, No. 10, October, 1976; Luner, 1984 Papermakers Conference or TAPPI, April, 1984, pp. 95-99; Sharpe, Merck and Co., Inc., Rahway, NJ, USA, around 1980, Chapter 5, "Polyelectrolyte Retention Aids";
Britt, TAPPI Vol. 56, October 1973, p. 46 ff.; and Waech, TAPPI, March, 1983, p. 137; or even US patent 4,388,150 (Eka Nobel).
The rEader is also referred to US patent 4,753,710 for all of the generalities related to paper production, the uaual additives i:sed, and similar details.
It is possible to replace the bentonite, as the secondary retention ai.d, with a kaolin, as described in the Applicant's French patezt application 95 13051, this kaolin preferably being pretreated +vith a polyelectralyte. One skilled in the art can=
refer to this French patent application 95 13051.
This p~ocess makes it possible to obtain a distinctly improved re:ention of fines and fillers without a reverse effect.
An addition3l characteristic of this improvement is that the drairiage pr)perties are improved.
The br=inched polyacrylamide (or more generally the branched (co)polymer is introduced into the suspension, in a distinctly preferred wiLy, in the form of a reverse phase water-in-ail emulsion at a rate of 0.03 to one per mill (0.03 to I%o, or 30 to 1,000 g/1) by weight of active material (polymer) relative to the dry weic=ht of the fibrous suspension, preferably 0.15 to 0.5 per nlill, oi= 150 to 500 g/t.
In a wcy that is known to one skilled in the art, the reverse pha:e emulsion polymer is diluted in water and inverted (solubized) by this dilution before its introduction, as described al ove .
This sElection of the reverse phase emulsion form'makes it possible, in the papermaking application for the retention of fillers and E%nes, to reach a level of performance unequalled up to now. MoreDver, the utilization of branched polymers make$ it possible to Dbtain a better retention of the bentonite in the sheet, as de3cribed in the above-mentioned Europeazi patent 0 574 335, and thu3 to limit its negative effects on the subsequent treatment c,f the effluents issuing from the machine. Furthermore, the choice of this branched polyacrylamide increases the fixation capat;-ty oT the th-e , corraequentl a synergy, and hence a recoagulation, which reduces the bentonite content in the white water.
It is understood that it is essential according to the invention that the polymer be prepared by means of a reverse phase oil-in-water emulsion polymerization. However, this polymer can then be used (i.e., injected or introduced into the mass or pulp to be Elocculated) either zn the form - preferably - of this reverse phase emulsion after its dissolution in water, or in the form of a p~wder obtained by drying (especially drying by means of "spray d--ying") the reverse phase emulsion from the polymerization, and then redissolving this powder in water, for example at i concentration on the order of 5 g of active polymer/lit:r, the solution thus obtained then being injected=
into the pu.p at substantially the same polymer dosages.
Advantitgeously, in practice, the branched (co)polyacrylamide is a cation:.c copolymer of acrylamide and of an unaaturated cationic et].ylenic monomer, chosen from. the group comprising dimethylami,i,oethyl acrylate (ADAME), dimethylaminoethyl methacrylate (MADAME), quaternized or salified by different acids and quateriiizing agents, benzyl chloride, methyl chloride, alkyl or aryl chicride, dimethyl sulfate, diallyldimethylammonium chloride (DFDMAC), acrylamidopropyltrimethylammonium chloride (APTAC), anc methacrylamidopropyltrimethylammonium chloride (MAPTAC).
In a knDwn way, this copolymer is branched by a branching agent consti:uted by a compound having at least two reagent groups chosei from the group comprising the double bonds, aldehyde bon3s, or epoxy bonds. These compounds are well known 15 and are desc=ibed, for example, in the document EP-A-0 374 458 (see also i.he Applicant's document FR-A-2 589 145).
As is known, a "branched" polymer is a polymer that has in the chain },ranches, groups or branchings globally disposed in one plane and i.ot in the three directions, unlike a"cross -linked"
polymer; branched polymers of this type, of high molecular weight, arE well known as flocculating agents. These branched polyacrylar.ides are distinguished from the cross-linked polyacrylan.ides by the fact that in the latter, the groups are disposed ttree dimensionally so as to lead to practically inso:iuble Froducta of infinite molecular weight.
The bzanching can be carried out preferably during (ox possibly after) the polymerization, for example by reaction of two solublE polymers having counter-ions, or by reaction on formaldehyc or a polyvalent metal compound. Often, the branching is carried out during the polymerization by the addition of a branching agent, and this method is clearly preferred according to the inve:ition. These processes for polymerization with branching are well known.
The branching agents that can be incorporated compriae ionic branching a;ents such aa polyvalernt metal salts, formaldehyde;
glyoxal, or even, preferably, covalent cxoss linkers that will copolymeriz: with the monomers, preferably monomers with diethylenic unsaturation (like the family of diacrylate esters such ae the diacrylates of polyethylene glycol PEG) or polyethylen_c unsaturation, of the type classically used for the cross-linki:ig of water-soluble polymers, and particula=ly methylenebi,sacrylamide (MBA), or any of the other known acrylic branching ai [enta .
These :igents are often identical to the croes linkers, but cross-linki]Lg can be avoided when desiring to obtain a polymer that is braiiched but not cross-linked, by optimizing polymerizat:on conditions such as the concentration of the polymerization, type and quantity of transfer agent, temperature, type and qt:ality of initiators, and the like.
In practice, the branching agent is methylenebisacrylamide (MHA), intzDduced at a rate of five to two hundred (5 to 200) moles per uillion moles of monomers, preferably 5 to 50.
Advantageously, the quantity of branched polyacrylamide introduced into the suspension to be flocculated is between thirty and Dne thousand grams of active polymer/ton of dry pulp (30 and 1,000 g/t), or between 0.03 per mill and one per mill, preferably 150 to 50o g/t; it was observed that if the quantity is lower th3n 0.03 %o (0.03 per mill), no significant retention is obtained; likewi.ee, if this quantity exceeds 1%o (1 per mill), no proportional improvement is observed; however, unlike the linear :-ationic polyacrylamides, as described in the documents E?-A-0 017 353 and EP 0 235 893 mentioned in the preaznble, tzere is no observed reverse dispersion effect by reci.rculati Dzz in the closed circuits of the excess polymer not retained in the sheet. Preferably, the quantity of branched polyacrylamide introduced is between 0.15 and 0.5 per mill (0.15 and 0.5 %o) of the quantity of dry pulp=, or between 150 g/t and 500 g/t.
As sta:ed above, it is important that the branched polymer be prepared in reverse phase (water-in-oil) emulsion form in order to aciieve the improvement of the invention. Emulsions of this type aid the process for preparing them are well known to one skilled in the art.
This a)proaCh was condemned in the above-mentioned European patent 0 57-: 335, in which it was indicated that if a branched polymer is =tsed in emulsion, the indispensable pre$ence of surfactants in these emulsions promotes the.formation of foams during the production of the paper and the appearance of disparities in the physical properties of the finished paper (modi:ficatiDn of the absorbency in the places where part of the oil phase cF the emulsion is retained in the sheet).
TherefDre, it was not obvious to consider a fortiori the reverse phase water-in-oil emulsions whose oil content is clearly high.
The invention was even more difficult to achieve in that it was importazt to stay within the field of branched polymer$ and not to cros3 over to the field of cross-linked polymers. It is known that --echnically, especially on an industrial production scale, the :)orderline between the two areas is very easily cxoased, in a way that is, moreover, irreversible. Since the branched ar!a is very limited, the difficulty of developing the invention ia considerable, and the Applicant desexves credit for undertaking to use of this technology in the field of paper production, which poses particular problems and has strict quality xeqiirements.
The ri;k of failure, which may explain the fact that this technology 'iad not been used, was even greater in that cross-linked emu7.sions are not known to provide any particular advantage i:i paper.
in comparison with the linear polymers, the branched polymers in powder form of the above-mentioned European patent 0 574 335 had already made substantial progress relative to the properties :nd the paper production process. The improvement was on the orde:= of 20 to 40 t depending on the properties.
With t):e present branched emulsions, an improvement on the order of 50 to 60 t is obtained, which would not have been foreseeable since, on the contrary, it wae known that the cro9s-linked prodi.cts did not work.
.9 Accorcing to the invention, in a preterxed but non-limiting way, a"mocerately branched" polymer is used, for example with 10 ppm of brar.ching agent relative to the active materiaJ._ As alieady indicated above, the polymer can be used either in the forn of its synthetic reverse-phase emulsion, dissolved or "inverted~ in water, or in the form of the solution in water of the powder Dbta.zned by dryi,ng said synthetic emulsion, :
part:icularly by means of spray-drying;. Spray-drying is a process that is al.eD known to one skilled in the art. The reader is referred tc the tests below in order to verify that the results are comparaz)le.
Bentonite, also known as "amectic swelling clay," from the montmorillo-iite family, is well known and there is no need to desc:ribe it in detail here; these compounds, formed'of microcrystaLlites, comprise surface sites having a high cation exchange ca:)acity capable of retaining water (see for example the document US-A-4 305 781, which corresponds to the document EP-A-0 017 353 men:ioned above, and FR-A-2 283 102), Preferibly, a semisodic bentonite is used, which is introduced just upstream from the headbox, at a rate of 0.1 to 0.5 percent (0.1 to 0.5$) of the dry weight of the fibrous suspension.
As a f.ller, it is possible to use kaolins, GCC or ground CaCO3, preci pitated CaCQ3 or PCC, and the like.
The br,Lnched polymer in reverse phase emulsion according to the inventio~n is injected or introduced prior to a shearing stage into the paper pulp (or fibrous mass to be flocculated;, which is more or lese; diluted*according to the,experience of one skilled in the art, and generally into the diluted paper pulp or "thin stock," i.e a pulp diluted to about D.7 to 1.5 % solid matter such as cel:ulose fibers, possible fillers, and the various additives ccmmonly used in papermaking.
Accorcing to a variant of the invention with fractionated introducticn, some of the branched polymer in emulsion according to the invention is introduced at the;level of the stage for preparing tze "thick stock" with about 5t or more solid matter, or even at :he level of the preparation of the thick stock before a shearing atage.
The foLlowing examples illustrate the invention without limiting ita scope.
LO B.7LAMPLE ].
Production of a branched Polvmer in the form of a reverse phaSe water-in-oi. _ emulaion L5 In a rF=actor A, the constituentsbf the organic phase of the emulsion to be synthesized are mixed at the ambient temperature.
a) Organic phase - 252 g of lxxsol. D100 M1 - 18 g of Slan 80 20 - 4 g of Hyxermer 2296 b) In a beaker B, the aqueous phase of'the emulsion to be produced is prepared by mixing:
- 385 g of a--rylamide at 50%
- 73 g of et:iyl acrylate trimethyl ammonium chloride 80%
>_5 - 268 g of w 3ter - 0.5 g of m:thylenebisacrylamide at 0.25%
- 0.75 ml of sodium bromate at 50 g l-1"
- 20 ppm of aodium hypophosphite relative to the active material - 0.29 ml of Versenex at 200 g 1"
;0 The con :ents of B are mixed into A under agitation. After =
the mixing o: the phases, the emulsion;is sheared in the mixer for 1 minute in order to create the revdrse ph&se emulsion. The emulsion is t.hen degassed by means of a nitrogen bubbling; then after 20 mini.tes the gradual addition o.f the metabisulfite Causes 5 the initiaticn followed by the polymeri;zation.
Crice the reaction is finished, a"buin out" (treatment with the metabisulfite) is carried out, in orde'r to reduce the fzee monomer content.
The etrzlsion ia then incorporated with it's inverting surfactant in order to subsequently release the polymer in the aqueous phaae. zt is necessary to int'roduce 2 to 2.4% ethoxylated alcohol_ T17: standard Brookfield viscosity of said polXmer is 4.36 cps (viscosity measured at 0.1% in a 1 M NaCl solution at 25 C at gix=y rpm).
In acc:)rdance with a variation of the MBA-content from 5 to ppm, the results in terms of UL viscosity are the following:
Table of Eximple 1:
Test 4BA NaH2POz, UL IR (1) IVR (2) State ?pm ppm (*) Viscosity N) (1) R 52 5 20 4.56 12.8 0 Branched R 102 10 20 3.74 28.9 0 Branched SD 102 LO 20 3.70 26 0 Branched X 104 LO 40 2.31 45 50' Cross-J. inked X 204 !0 40 2.61 54.8 50 Cross-linked EM 140CT ) 15 4.5 0; 0 Linear EM 140L 30 3.82 a 0. Linear EM 14 OLI3 11 40 3.16 0' <, 0 Linear :0 100 Cross-EM 140BD 0 1.85 8!
~linked FO 4198 ! 20 3.2 5 <10 Branched FO 4198 : a k ranched powder containing 2;0 ppm tr,azlsfer agent and 5 ppm branchirg agent.
{*} , ac dium hypophosphite, tran$fex agent = , p r (1) . :.onic regain in (2) ntrinsic viscosity regain in 96 EM140CT: z. standard emulsion of very,high molecular weight =
containing no branching age'nt EM 140L: standard emulsion of high:~molecul;ar weight containing ro branching agent EM140LH: Fn emulsion of average molecular we~ight containing no Yranching agent EM140HD: a cross-linked emulsion containing no transfer agent E:nd 5 ppm cross linker f SD 102: the emulsion R 102 dried by; spray-drying, and the r~wder obtained dissolved in water to 5 g of active FDlymer/liter ~..
It is :ioted that the linear prod~cts do Zot develop any ionic regaii IR, and their intrinsic vi . seosity,IV decreases under ;=
the effect ~f an intense shearing (two'of thelIV values are negative); :he branched products in erl'x:ulsion develop an ionic regain IR, 3ut no YV (values <= 0); the cross=linked products develop a h.gh ionic regain and a very,'high Iv'regain.
Definitions of the ionic regains and itiitrins],c viscosity regains:
Ionic regain IR = (X-Y) /Y x 100 with X . ionicity after shearing in meq/;g, Y ionicity before shearirig in meci/g.
Intrinsic viscosity regain IVR= (Vl-V2?-/V2 x.100 with Vl intrinsic'viscosity aftr sheari ng in dl/g i V2 intrinsic viscosity before shearing in dl/g ~=
Some of the emulsions cited above( will beAhe subjects of a study of effectiveness in retention an~_ drainag,e in an automated ' sheet formex at the Center for Paper Technology.
r , i.
ci Procedure :'or testing the emulsions Pulp used=
mixture of 70t bleached hardwood kraft KF
10% b:.eached softwood kraft KR
20t mE:chanical pulp PM
20t n;.tural calcium carbonate.
t:izing in a neutral medium lwi.th 2% of an alkyl ketene c.imer emulsion.
The pi.lp used is diluted to a cmsistency of 1.5%. A sample of 2.24 dr,' g of pulp, or 149 g of pu' p at 150%, is taken, then diluted to 0.4% with clear water.
}
The 5E0 ml volume is introduced anto the-plexiglass cylinder of the autcmated sheet former, and thre sequence is begun.
s, .
- t 0 s, start of agitation at 41500 rpm.
, - t 10 s, addition of the polyme 3.
- t 60 8, automatic reduction tol'1000 rpm and, if necessary, addition of the benton-Xte.
- t 75 s, stopping of the agitatlion, formation of the sheet with vacuum under the uire, followed by reclamation of the white water.
The fcllowing operations are then carried out:
- measuxement of the turbidity of theswater under the wire.
- dilution of a beaker of thick stock;;for a new sheet with the reclaimed uater under the wire.
- drying of the so-called 1st pass sheet.
- start of a new sequence for producing the so-called 2nd pass sheet.
~. , After 3 passes, the products to be tested are changed.
The following analyses are then performed:
- measuremezt of the matter in suspension in the water under the wire (TAPP; standard: T 656 cm/83) - measuremont of the ash in the sheee (TAPPI standard: T 211 om-93) - measux=emE nt of turbidity 301 after the fibers are deposited in order to lf arn the state of the ionicdl medium.
- measuremEnt of the degree of drainability of the pulp with'a Canadian Standard Freeness (CSF; TApPIT standar'd T 227 om - 94).
Notes for 7 ables (Y) and (I1) below:
X = Eo-ca].led first-pass measur'oment R1 = :o-called second pass-measu~ement (lst recycling) R2 = Eo-called third pass measurment (2nd recycling) Ash% I by weight of ash retainedk(= filler retention) in the sheet/weigYt of the sheet.
p Comments oA the results : see Tables (I) and(lT) belovv relative ~
to Rxaumle 1, and Fic.Is 1 throuq~h 10, ilwhich represent the corresoondi acr histoarams The cr)ss-linked polymers have no advantage as to the flocculatio z and the retention of fin's and fillers in spite of the high ra:e of shear applied duringi he process to the fibrous mass (and n.)t applied to the polymer i self), in this case 1,500 G =
rpm, which -s characteristic of this t~ e of micropaxticulate retention s.-stem. They show a poor ca~ure of fillers and colloidal mLtter, since no reduction turbidity is observed_ The cottbination with bentonite do s not significantly improve the effectiveness in terms of etention and only sli.ghtly improves thE effectiveness in terms of~ drainage.
As for the linear polymer, its b avior followa the tendency to improve the retention of fillers fines.
The combination according to the invention of a branched polymer in reverse phase emulsion and bentonite provides a net gain in filler retention and in total retention, and is revealed to be superior to the known linear polymer/bentonite system.
The coagulation capacity is better for a branched polymer in emulsion, which translates into an excellent reduction in the turbidity at 30' (30 min.).
The R 52 test and the R 102 test show that the invention makes it possible to obtain branched products having UL
viscosities higher than those accessible through gel polymerization as described in European patent 0 574 335. Any attempt to reach such highly advantageous UL viscosity values using a gel polymerization process with drying into a powder would result in a product that was totally insoluble and therefore totally unusable in the industry.
The SD 102 test shows that the polymer used in the form of a solution in water of the powder obtained by drying the reverse phase emulsion from the synthesis of the polymer behaves like the polymer used in the form of the solution in water of said synthetic reverse phase emulsion. In particular, no degradation of the polymer is observed during the stage for drying by means of spray-drying.
It is useful to compare the R 52 test to the FO 4198 test (powder), since the polymers have the same chemistry, hence the same cationicity, and the same % of MBA, while the R52 of the invention is far superior to the powder in terms of drainage and retention (96.3 as compared to 83.6); compare also the turbidity in NTU after 30 minutes, 32 as compared to 75 NTU units.
Such UL viscosity values specifically result in substantially improved drainage.
The irvention also relates to a novel retention aid fox' the production of a sheet of paper, paperboard or the like, which is comprised cf a branched acrylic (co)polymer as described above, in reverse phase emulsion, which is characterized in that its UL
viscosity is > 3, or > 3.5 or > 4. Said agent can be used either in emulsior, inverted in water, or in a solution of the powder obtained by drying the emulsion, as described above.
Production af a branched acrylama.dopropvltrimethvlaumloni.um chloride (PTAC) baeed polymer in the form of a reverse phase oil-in-water emulsion:
In a r~actor A, the constituents of the organic phase of the emulsion to be synthesized are mixed at the ambient temperature.
a) Organic :)hase - 252 g of sxxsol D100 - 18 g of S: )an 80 - 4 g of Hy, )ermer 2296 b) In a bea]:er B, the phase of the emuleion to be produced is prepared by mixing:
- 378 g of i.crylamide at 50%
~ 102.2 g oi acrylamidopropyltrimethylamonium chloride (60t) - 245.7 g oi water - 0.5 g of r.ethylenebisacrylamide at 0.25%
0.75 ml oi sodium bromate at 50 g/l 30 - 20 ppm of sodium hypophosphite relative to the active material - 0.29 mJ, of Versenex at 200 g/1 The cortents of B are mixed into A under agitation. After the mixing cf the phases, the emulsion is sheared in the mixer.
for 1 minutE in order to create the reverse-phase emulsion. The emulsion is then degassed by means of a nitrogen bubbling; then after 20 mizutes, the gradual addition of the metabisulfite causes the initiation followed by the polymerization.
Once t3e reaction is finished, a "burn out" is carried out in order to reduce the free monomer content.
The emi].sion is then incorporated with its inverting surfactant _n order to subsequently free the polymer in the aqueous pha :e .
Table of Ex. op1e 2:
Test M3.A NaI12PO UL IR (1) IVR (2) State p )m ppm Viscosity (t) (~) M 52 5 20 4.20 14.2 a Branched M 102 1) 20 3.34 21.3 0 Branched XM 104 1) 40 2. Z1 37 50 Cross-linked XM 204 2) 40 1-94 58 55 Cross-linked EK 190 0 15 4.35 0. 0 Linear EK 190 5 0 1.85 78 60 Cross-BD linked =
EK 190: a standard emulsion of a copolymer of acrylamide and acrylamidopxopyltrimethylammonium chloride, linear.
Procedure fc r testi.ncr the emulsions (identical to that of Examp7.e 1) Comments on the resuZts: see Table (TZZ) below relative to Example 2, a id F,iga . 11 throuc[h 20, which represent the corxesyondin I histacxrams The rEsults invite the same comments as those of Example 1 and confirn the great advantage of the preaent invention.
The irvention also relates to the novel xetention aids described zbove, characterized in that they consist of, or comprise, tt least one branched (co)polymer of the type described, prepared in reverse phase emulsion, intended to cooperate hith a secondary retention aid after an intermediate stage for --hearing the paper pulp, as well as to the processes for producing sheets of paper, paperboard or the like using the agents acccrding to the invention or the process according to the invention, and the sheets of paper, paperboard and the like thus obtained.
Said agent can be used either in emulsion inverted in water, or in a solition of the powder obtained by drying the emulsion, as describe3 above.
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In thE document EP-A-0 017 353, it was proposed, for the retention cf low-filler pulps (less than 5jk fillers), to associate the bentonite with a nonionic to slightly anionic linear copclyacrylamide. This process has not been very widely used, sincE these polymers perform relatively poorly in terms of retention, especially that of pulps containing fillers, no doubt as a result of inaufficient synergy between these copolymers and bentonite, which does not have much of a tendency to recoagulate.
1.5 In the document EP-A-0-235 893, it was proposed to use essentiall} linear cationic polyacrylamides having molecular weights of greater than one million, of thirty million and higher. This resulte in the obtainment-of a retention effect that is satisfactory, but is still deemed inadequate in the papermaking application; since the use of bentonite causes problems during the subsequent treatment of the effluents issuing from the ma::hine, users select this system on].y if there are significant advantages.
In the notes presented at the lecture given in Seattle on October 11-L3, 1989, published under the title "Supercoagulation in the cont:ol of wet end chemistry by synthetic polymer and activated b;ntonite," R. Rajasvixta described the mechanism of -supercoagulition of activated bentonite in the presencd of a cationic po_yacrylamide, without specifying its exact nature.
This proces, has the same drawbacks as above.
Lastly European Patent 0 574 335 produced an impox-tant improvement by proposing the use branched polymers (particularly polyacrylam,des) in powder form.
The invention eliminates the drawbacks mentioned above.
According to one aspect of the invention, there is provided a process for manufacturing a sheet of paper or paperboard having improved retention and drainage properties, of the type which uses a dual system of an acrylic polymer and bentonite or a possibly treated kaolin as the primary and secondary retention agents, respectively, the introductions of which are separated by a stage for shearing the suspension or fibrous mass or paper pulp, characterized in that said polymer is a branched acrylic (co)polymer prepared in the form of a reverse phase water-in-oil emulsion, used either in emulsion reversed in water or in a solution of the powder obtained by drying the emulsion, said branched acrylic (co)polymer being introduced into the paper pulp at a concentration of 0.03 to one per mill (0.03 to 1 %o) by weight or 30 to 1,000 g/t, of the dry weight of the fibrous suspension of paper pulp, wherein its UL viscosity is > 3.
Its object is to obtain an improved process of the type in question, which is comprised of adding to the suspension or fibrous mass or paper pulp to be flocculated, as the main retention aid, an agent consisting of or comprising a branched polyacrylamide which is characterized in that it has been prepared in reverse phase or water-in-oil emulsion, and bentonite as the second retention aid (a so-called "dual" system of the type also known as "microparticulate").
The phrase "exists in reverse phase emulsion" or similar expressions related to the polymer used (i.e., injected or introduced into the pulp to be flocculated) according to the invention, will be understood by one skilled in the art to designate the reverse phase water-in-oil emulsion that is dissolved in water before its injection or its introduction into the mass or pulp to be flocculated (this dissolution in water results in what is known as the "reversal" of the initial reverse phase water-in-oil emulsion; these processes are well known to 85750-14 3a one skilled in the art).
The additions of the polymer and the bentonite are separated by a shearing stage, for example at the level of the mixing pump known as a "fan pump." In this field, the reader is referred to the specification of US patent 4,753,710, as well as to a vast body of prior art related to the addition point of the retention aid relative to the shearing stages existing in the machine, including US patent 3,052,595; Unbehend, TAPPI Vol. 59, No. 10, October, 1976; Luner, 1984 Papermakers Conference or TAPPI, April, 1984, pp. 95-99; Sharpe, Merck and Co., Inc., Rahway, NJ, USA, around 1980, Chapter 5, "Polyelectrolyte Retention Aids";
Britt, TAPPI Vol. 56, October 1973, p. 46 ff.; and Waech, TAPPI, March, 1983, p. 137; or even US patent 4,388,150 (Eka Nobel).
The rEader is also referred to US patent 4,753,710 for all of the generalities related to paper production, the uaual additives i:sed, and similar details.
It is possible to replace the bentonite, as the secondary retention ai.d, with a kaolin, as described in the Applicant's French patezt application 95 13051, this kaolin preferably being pretreated +vith a polyelectralyte. One skilled in the art can=
refer to this French patent application 95 13051.
This p~ocess makes it possible to obtain a distinctly improved re:ention of fines and fillers without a reverse effect.
An addition3l characteristic of this improvement is that the drairiage pr)perties are improved.
The br=inched polyacrylamide (or more generally the branched (co)polymer is introduced into the suspension, in a distinctly preferred wiLy, in the form of a reverse phase water-in-ail emulsion at a rate of 0.03 to one per mill (0.03 to I%o, or 30 to 1,000 g/1) by weight of active material (polymer) relative to the dry weic=ht of the fibrous suspension, preferably 0.15 to 0.5 per nlill, oi= 150 to 500 g/t.
In a wcy that is known to one skilled in the art, the reverse pha:e emulsion polymer is diluted in water and inverted (solubized) by this dilution before its introduction, as described al ove .
This sElection of the reverse phase emulsion form'makes it possible, in the papermaking application for the retention of fillers and E%nes, to reach a level of performance unequalled up to now. MoreDver, the utilization of branched polymers make$ it possible to Dbtain a better retention of the bentonite in the sheet, as de3cribed in the above-mentioned Europeazi patent 0 574 335, and thu3 to limit its negative effects on the subsequent treatment c,f the effluents issuing from the machine. Furthermore, the choice of this branched polyacrylamide increases the fixation capat;-ty oT the th-e , corraequentl a synergy, and hence a recoagulation, which reduces the bentonite content in the white water.
It is understood that it is essential according to the invention that the polymer be prepared by means of a reverse phase oil-in-water emulsion polymerization. However, this polymer can then be used (i.e., injected or introduced into the mass or pulp to be Elocculated) either zn the form - preferably - of this reverse phase emulsion after its dissolution in water, or in the form of a p~wder obtained by drying (especially drying by means of "spray d--ying") the reverse phase emulsion from the polymerization, and then redissolving this powder in water, for example at i concentration on the order of 5 g of active polymer/lit:r, the solution thus obtained then being injected=
into the pu.p at substantially the same polymer dosages.
Advantitgeously, in practice, the branched (co)polyacrylamide is a cation:.c copolymer of acrylamide and of an unaaturated cationic et].ylenic monomer, chosen from. the group comprising dimethylami,i,oethyl acrylate (ADAME), dimethylaminoethyl methacrylate (MADAME), quaternized or salified by different acids and quateriiizing agents, benzyl chloride, methyl chloride, alkyl or aryl chicride, dimethyl sulfate, diallyldimethylammonium chloride (DFDMAC), acrylamidopropyltrimethylammonium chloride (APTAC), anc methacrylamidopropyltrimethylammonium chloride (MAPTAC).
In a knDwn way, this copolymer is branched by a branching agent consti:uted by a compound having at least two reagent groups chosei from the group comprising the double bonds, aldehyde bon3s, or epoxy bonds. These compounds are well known 15 and are desc=ibed, for example, in the document EP-A-0 374 458 (see also i.he Applicant's document FR-A-2 589 145).
As is known, a "branched" polymer is a polymer that has in the chain },ranches, groups or branchings globally disposed in one plane and i.ot in the three directions, unlike a"cross -linked"
polymer; branched polymers of this type, of high molecular weight, arE well known as flocculating agents. These branched polyacrylar.ides are distinguished from the cross-linked polyacrylan.ides by the fact that in the latter, the groups are disposed ttree dimensionally so as to lead to practically inso:iuble Froducta of infinite molecular weight.
The bzanching can be carried out preferably during (ox possibly after) the polymerization, for example by reaction of two solublE polymers having counter-ions, or by reaction on formaldehyc or a polyvalent metal compound. Often, the branching is carried out during the polymerization by the addition of a branching agent, and this method is clearly preferred according to the inve:ition. These processes for polymerization with branching are well known.
The branching agents that can be incorporated compriae ionic branching a;ents such aa polyvalernt metal salts, formaldehyde;
glyoxal, or even, preferably, covalent cxoss linkers that will copolymeriz: with the monomers, preferably monomers with diethylenic unsaturation (like the family of diacrylate esters such ae the diacrylates of polyethylene glycol PEG) or polyethylen_c unsaturation, of the type classically used for the cross-linki:ig of water-soluble polymers, and particula=ly methylenebi,sacrylamide (MBA), or any of the other known acrylic branching ai [enta .
These :igents are often identical to the croes linkers, but cross-linki]Lg can be avoided when desiring to obtain a polymer that is braiiched but not cross-linked, by optimizing polymerizat:on conditions such as the concentration of the polymerization, type and quantity of transfer agent, temperature, type and qt:ality of initiators, and the like.
In practice, the branching agent is methylenebisacrylamide (MHA), intzDduced at a rate of five to two hundred (5 to 200) moles per uillion moles of monomers, preferably 5 to 50.
Advantageously, the quantity of branched polyacrylamide introduced into the suspension to be flocculated is between thirty and Dne thousand grams of active polymer/ton of dry pulp (30 and 1,000 g/t), or between 0.03 per mill and one per mill, preferably 150 to 50o g/t; it was observed that if the quantity is lower th3n 0.03 %o (0.03 per mill), no significant retention is obtained; likewi.ee, if this quantity exceeds 1%o (1 per mill), no proportional improvement is observed; however, unlike the linear :-ationic polyacrylamides, as described in the documents E?-A-0 017 353 and EP 0 235 893 mentioned in the preaznble, tzere is no observed reverse dispersion effect by reci.rculati Dzz in the closed circuits of the excess polymer not retained in the sheet. Preferably, the quantity of branched polyacrylamide introduced is between 0.15 and 0.5 per mill (0.15 and 0.5 %o) of the quantity of dry pulp=, or between 150 g/t and 500 g/t.
As sta:ed above, it is important that the branched polymer be prepared in reverse phase (water-in-oil) emulsion form in order to aciieve the improvement of the invention. Emulsions of this type aid the process for preparing them are well known to one skilled in the art.
This a)proaCh was condemned in the above-mentioned European patent 0 57-: 335, in which it was indicated that if a branched polymer is =tsed in emulsion, the indispensable pre$ence of surfactants in these emulsions promotes the.formation of foams during the production of the paper and the appearance of disparities in the physical properties of the finished paper (modi:ficatiDn of the absorbency in the places where part of the oil phase cF the emulsion is retained in the sheet).
TherefDre, it was not obvious to consider a fortiori the reverse phase water-in-oil emulsions whose oil content is clearly high.
The invention was even more difficult to achieve in that it was importazt to stay within the field of branched polymer$ and not to cros3 over to the field of cross-linked polymers. It is known that --echnically, especially on an industrial production scale, the :)orderline between the two areas is very easily cxoased, in a way that is, moreover, irreversible. Since the branched ar!a is very limited, the difficulty of developing the invention ia considerable, and the Applicant desexves credit for undertaking to use of this technology in the field of paper production, which poses particular problems and has strict quality xeqiirements.
The ri;k of failure, which may explain the fact that this technology 'iad not been used, was even greater in that cross-linked emu7.sions are not known to provide any particular advantage i:i paper.
in comparison with the linear polymers, the branched polymers in powder form of the above-mentioned European patent 0 574 335 had already made substantial progress relative to the properties :nd the paper production process. The improvement was on the orde:= of 20 to 40 t depending on the properties.
With t):e present branched emulsions, an improvement on the order of 50 to 60 t is obtained, which would not have been foreseeable since, on the contrary, it wae known that the cro9s-linked prodi.cts did not work.
.9 Accorcing to the invention, in a preterxed but non-limiting way, a"mocerately branched" polymer is used, for example with 10 ppm of brar.ching agent relative to the active materiaJ._ As alieady indicated above, the polymer can be used either in the forn of its synthetic reverse-phase emulsion, dissolved or "inverted~ in water, or in the form of the solution in water of the powder Dbta.zned by dryi,ng said synthetic emulsion, :
part:icularly by means of spray-drying;. Spray-drying is a process that is al.eD known to one skilled in the art. The reader is referred tc the tests below in order to verify that the results are comparaz)le.
Bentonite, also known as "amectic swelling clay," from the montmorillo-iite family, is well known and there is no need to desc:ribe it in detail here; these compounds, formed'of microcrystaLlites, comprise surface sites having a high cation exchange ca:)acity capable of retaining water (see for example the document US-A-4 305 781, which corresponds to the document EP-A-0 017 353 men:ioned above, and FR-A-2 283 102), Preferibly, a semisodic bentonite is used, which is introduced just upstream from the headbox, at a rate of 0.1 to 0.5 percent (0.1 to 0.5$) of the dry weight of the fibrous suspension.
As a f.ller, it is possible to use kaolins, GCC or ground CaCO3, preci pitated CaCQ3 or PCC, and the like.
The br,Lnched polymer in reverse phase emulsion according to the inventio~n is injected or introduced prior to a shearing stage into the paper pulp (or fibrous mass to be flocculated;, which is more or lese; diluted*according to the,experience of one skilled in the art, and generally into the diluted paper pulp or "thin stock," i.e a pulp diluted to about D.7 to 1.5 % solid matter such as cel:ulose fibers, possible fillers, and the various additives ccmmonly used in papermaking.
Accorcing to a variant of the invention with fractionated introducticn, some of the branched polymer in emulsion according to the invention is introduced at the;level of the stage for preparing tze "thick stock" with about 5t or more solid matter, or even at :he level of the preparation of the thick stock before a shearing atage.
The foLlowing examples illustrate the invention without limiting ita scope.
LO B.7LAMPLE ].
Production of a branched Polvmer in the form of a reverse phaSe water-in-oi. _ emulaion L5 In a rF=actor A, the constituentsbf the organic phase of the emulsion to be synthesized are mixed at the ambient temperature.
a) Organic phase - 252 g of lxxsol. D100 M1 - 18 g of Slan 80 20 - 4 g of Hyxermer 2296 b) In a beaker B, the aqueous phase of'the emulsion to be produced is prepared by mixing:
- 385 g of a--rylamide at 50%
- 73 g of et:iyl acrylate trimethyl ammonium chloride 80%
>_5 - 268 g of w 3ter - 0.5 g of m:thylenebisacrylamide at 0.25%
- 0.75 ml of sodium bromate at 50 g l-1"
- 20 ppm of aodium hypophosphite relative to the active material - 0.29 ml of Versenex at 200 g 1"
;0 The con :ents of B are mixed into A under agitation. After =
the mixing o: the phases, the emulsion;is sheared in the mixer for 1 minute in order to create the revdrse ph&se emulsion. The emulsion is t.hen degassed by means of a nitrogen bubbling; then after 20 mini.tes the gradual addition o.f the metabisulfite Causes 5 the initiaticn followed by the polymeri;zation.
Crice the reaction is finished, a"buin out" (treatment with the metabisulfite) is carried out, in orde'r to reduce the fzee monomer content.
The etrzlsion ia then incorporated with it's inverting surfactant in order to subsequently release the polymer in the aqueous phaae. zt is necessary to int'roduce 2 to 2.4% ethoxylated alcohol_ T17: standard Brookfield viscosity of said polXmer is 4.36 cps (viscosity measured at 0.1% in a 1 M NaCl solution at 25 C at gix=y rpm).
In acc:)rdance with a variation of the MBA-content from 5 to ppm, the results in terms of UL viscosity are the following:
Table of Eximple 1:
Test 4BA NaH2POz, UL IR (1) IVR (2) State ?pm ppm (*) Viscosity N) (1) R 52 5 20 4.56 12.8 0 Branched R 102 10 20 3.74 28.9 0 Branched SD 102 LO 20 3.70 26 0 Branched X 104 LO 40 2.31 45 50' Cross-J. inked X 204 !0 40 2.61 54.8 50 Cross-linked EM 140CT ) 15 4.5 0; 0 Linear EM 140L 30 3.82 a 0. Linear EM 14 OLI3 11 40 3.16 0' <, 0 Linear :0 100 Cross-EM 140BD 0 1.85 8!
~linked FO 4198 ! 20 3.2 5 <10 Branched FO 4198 : a k ranched powder containing 2;0 ppm tr,azlsfer agent and 5 ppm branchirg agent.
{*} , ac dium hypophosphite, tran$fex agent = , p r (1) . :.onic regain in (2) ntrinsic viscosity regain in 96 EM140CT: z. standard emulsion of very,high molecular weight =
containing no branching age'nt EM 140L: standard emulsion of high:~molecul;ar weight containing ro branching agent EM140LH: Fn emulsion of average molecular we~ight containing no Yranching agent EM140HD: a cross-linked emulsion containing no transfer agent E:nd 5 ppm cross linker f SD 102: the emulsion R 102 dried by; spray-drying, and the r~wder obtained dissolved in water to 5 g of active FDlymer/liter ~..
It is :ioted that the linear prod~cts do Zot develop any ionic regaii IR, and their intrinsic vi . seosity,IV decreases under ;=
the effect ~f an intense shearing (two'of thelIV values are negative); :he branched products in erl'x:ulsion develop an ionic regain IR, 3ut no YV (values <= 0); the cross=linked products develop a h.gh ionic regain and a very,'high Iv'regain.
Definitions of the ionic regains and itiitrins],c viscosity regains:
Ionic regain IR = (X-Y) /Y x 100 with X . ionicity after shearing in meq/;g, Y ionicity before shearirig in meci/g.
Intrinsic viscosity regain IVR= (Vl-V2?-/V2 x.100 with Vl intrinsic'viscosity aftr sheari ng in dl/g i V2 intrinsic viscosity before shearing in dl/g ~=
Some of the emulsions cited above( will beAhe subjects of a study of effectiveness in retention an~_ drainag,e in an automated ' sheet formex at the Center for Paper Technology.
r , i.
ci Procedure :'or testing the emulsions Pulp used=
mixture of 70t bleached hardwood kraft KF
10% b:.eached softwood kraft KR
20t mE:chanical pulp PM
20t n;.tural calcium carbonate.
t:izing in a neutral medium lwi.th 2% of an alkyl ketene c.imer emulsion.
The pi.lp used is diluted to a cmsistency of 1.5%. A sample of 2.24 dr,' g of pulp, or 149 g of pu' p at 150%, is taken, then diluted to 0.4% with clear water.
}
The 5E0 ml volume is introduced anto the-plexiglass cylinder of the autcmated sheet former, and thre sequence is begun.
s, .
- t 0 s, start of agitation at 41500 rpm.
, - t 10 s, addition of the polyme 3.
- t 60 8, automatic reduction tol'1000 rpm and, if necessary, addition of the benton-Xte.
- t 75 s, stopping of the agitatlion, formation of the sheet with vacuum under the uire, followed by reclamation of the white water.
The fcllowing operations are then carried out:
- measuxement of the turbidity of theswater under the wire.
- dilution of a beaker of thick stock;;for a new sheet with the reclaimed uater under the wire.
- drying of the so-called 1st pass sheet.
- start of a new sequence for producing the so-called 2nd pass sheet.
~. , After 3 passes, the products to be tested are changed.
The following analyses are then performed:
- measuremezt of the matter in suspension in the water under the wire (TAPP; standard: T 656 cm/83) - measuremont of the ash in the sheee (TAPPI standard: T 211 om-93) - measux=emE nt of turbidity 301 after the fibers are deposited in order to lf arn the state of the ionicdl medium.
- measuremEnt of the degree of drainability of the pulp with'a Canadian Standard Freeness (CSF; TApPIT standar'd T 227 om - 94).
Notes for 7 ables (Y) and (I1) below:
X = Eo-ca].led first-pass measur'oment R1 = :o-called second pass-measu~ement (lst recycling) R2 = Eo-called third pass measurment (2nd recycling) Ash% I by weight of ash retainedk(= filler retention) in the sheet/weigYt of the sheet.
p Comments oA the results : see Tables (I) and(lT) belovv relative ~
to Rxaumle 1, and Fic.Is 1 throuq~h 10, ilwhich represent the corresoondi acr histoarams The cr)ss-linked polymers have no advantage as to the flocculatio z and the retention of fin's and fillers in spite of the high ra:e of shear applied duringi he process to the fibrous mass (and n.)t applied to the polymer i self), in this case 1,500 G =
rpm, which -s characteristic of this t~ e of micropaxticulate retention s.-stem. They show a poor ca~ure of fillers and colloidal mLtter, since no reduction turbidity is observed_ The cottbination with bentonite do s not significantly improve the effectiveness in terms of etention and only sli.ghtly improves thE effectiveness in terms of~ drainage.
As for the linear polymer, its b avior followa the tendency to improve the retention of fillers fines.
The combination according to the invention of a branched polymer in reverse phase emulsion and bentonite provides a net gain in filler retention and in total retention, and is revealed to be superior to the known linear polymer/bentonite system.
The coagulation capacity is better for a branched polymer in emulsion, which translates into an excellent reduction in the turbidity at 30' (30 min.).
The R 52 test and the R 102 test show that the invention makes it possible to obtain branched products having UL
viscosities higher than those accessible through gel polymerization as described in European patent 0 574 335. Any attempt to reach such highly advantageous UL viscosity values using a gel polymerization process with drying into a powder would result in a product that was totally insoluble and therefore totally unusable in the industry.
The SD 102 test shows that the polymer used in the form of a solution in water of the powder obtained by drying the reverse phase emulsion from the synthesis of the polymer behaves like the polymer used in the form of the solution in water of said synthetic reverse phase emulsion. In particular, no degradation of the polymer is observed during the stage for drying by means of spray-drying.
It is useful to compare the R 52 test to the FO 4198 test (powder), since the polymers have the same chemistry, hence the same cationicity, and the same % of MBA, while the R52 of the invention is far superior to the powder in terms of drainage and retention (96.3 as compared to 83.6); compare also the turbidity in NTU after 30 minutes, 32 as compared to 75 NTU units.
Such UL viscosity values specifically result in substantially improved drainage.
The irvention also relates to a novel retention aid fox' the production of a sheet of paper, paperboard or the like, which is comprised cf a branched acrylic (co)polymer as described above, in reverse phase emulsion, which is characterized in that its UL
viscosity is > 3, or > 3.5 or > 4. Said agent can be used either in emulsior, inverted in water, or in a solution of the powder obtained by drying the emulsion, as described above.
Production af a branched acrylama.dopropvltrimethvlaumloni.um chloride (PTAC) baeed polymer in the form of a reverse phase oil-in-water emulsion:
In a r~actor A, the constituents of the organic phase of the emulsion to be synthesized are mixed at the ambient temperature.
a) Organic :)hase - 252 g of sxxsol D100 - 18 g of S: )an 80 - 4 g of Hy, )ermer 2296 b) In a bea]:er B, the phase of the emuleion to be produced is prepared by mixing:
- 378 g of i.crylamide at 50%
~ 102.2 g oi acrylamidopropyltrimethylamonium chloride (60t) - 245.7 g oi water - 0.5 g of r.ethylenebisacrylamide at 0.25%
0.75 ml oi sodium bromate at 50 g/l 30 - 20 ppm of sodium hypophosphite relative to the active material - 0.29 mJ, of Versenex at 200 g/1 The cortents of B are mixed into A under agitation. After the mixing cf the phases, the emulsion is sheared in the mixer.
for 1 minutE in order to create the reverse-phase emulsion. The emulsion is then degassed by means of a nitrogen bubbling; then after 20 mizutes, the gradual addition of the metabisulfite causes the initiation followed by the polymerization.
Once t3e reaction is finished, a "burn out" is carried out in order to reduce the free monomer content.
The emi].sion is then incorporated with its inverting surfactant _n order to subsequently free the polymer in the aqueous pha :e .
Table of Ex. op1e 2:
Test M3.A NaI12PO UL IR (1) IVR (2) State p )m ppm Viscosity (t) (~) M 52 5 20 4.20 14.2 a Branched M 102 1) 20 3.34 21.3 0 Branched XM 104 1) 40 2. Z1 37 50 Cross-linked XM 204 2) 40 1-94 58 55 Cross-linked EK 190 0 15 4.35 0. 0 Linear EK 190 5 0 1.85 78 60 Cross-BD linked =
EK 190: a standard emulsion of a copolymer of acrylamide and acrylamidopxopyltrimethylammonium chloride, linear.
Procedure fc r testi.ncr the emulsions (identical to that of Examp7.e 1) Comments on the resuZts: see Table (TZZ) below relative to Example 2, a id F,iga . 11 throuc[h 20, which represent the corxesyondin I histacxrams The rEsults invite the same comments as those of Example 1 and confirn the great advantage of the preaent invention.
The irvention also relates to the novel xetention aids described zbove, characterized in that they consist of, or comprise, tt least one branched (co)polymer of the type described, prepared in reverse phase emulsion, intended to cooperate hith a secondary retention aid after an intermediate stage for --hearing the paper pulp, as well as to the processes for producing sheets of paper, paperboard or the like using the agents acccrding to the invention or the process according to the invention, and the sheets of paper, paperboard and the like thus obtained.
Said agent can be used either in emulsion inverted in water, or in a solition of the powder obtained by drying the emulsion, as describe3 above.
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Claims (18)
1. A process for manufacturing a sheet of paper or paperboard having improved retention and drainage properties, of the type which uses a dual system of an acrylic polymer and bentonite or a possibly treated kaolin as the primary and secondary retention agents, respectively, the introductions of which are separated by a stage for shearing the suspension or fibrous mass or paper pulp, characterized in that said polymer is a branched acrylic (co)polymer prepared in the form of a reverse phase water-in-oil emulsion, used either in emulsion reversed in water or in a solution of the powder obtained by drying the emulsion, said branched acrylic (co)polymer being introduced into the paper pulp at a concentration of 0.03 to one per mill (0.03 to 1 %o) by weight or 30 to 1,000 g/t, of the dry weight of the fibrous suspension of paper pulp, wherein its UL viscosity is > 3.
2. The process according to claim 1, wherein the branched acrylic (co)polymer is introduced into the paper pulp at a concentration of 0.15 to 0.5 per mill (0.15 to 0.5 %o) or 150 to 500 g/t.
3. The process according to claim 1 or 2, wherein the UL
viscosity of the branched acrylic (co)polymer is > 3.5.
viscosity of the branched acrylic (co)polymer is > 3.5.
4. The process according to claim 1 or 2, wherein the UL
viscosity of the branched acrylic (co)polymer is > 4.
viscosity of the branched acrylic (co)polymer is > 4.
5. The process according to any of claims 1 to 4, wherein the branched acrylic (co)polymer prepared in reverse phase emulsion is a cationic copolymer of acrylamide and of an unsaturated cationic ethylenic monomer chosen from the group comprising dimethylaminoethyl acrylate (ADAME), dimethylaminoethyl methacrylate (MADAME), quaternized or salified by different acids and quaternizing agents, benzyl chloride, methyl chloride, alkyl or aryl chlorides, dimethyl sulfate, diallyldimethylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC), and methacrylamidopropylthymethylammonium chloride (MAPTAC).
6. The process according to any of claims 1 to 5, wherein the branched acrylic (co)polymer in reverse phase emulsion is branched by means of a branching agent constituted by a polyfunctional compound having at least two reagent groups chosen from the group consisting of the double bonds, the aldehyde bonds and the epoxy bonds.
7. The process according to any of claims 1 to 6, wherein the branched acrylic (co)polymer in reverse phase emulsion is branched by means of a branching agent constituted by methylenebisacrylamide (MBA) at a concentration of 5 to 200 moles per million moles of monomers.
8. The process according to claim 7, wherein the bentonite is a semisodic bentonite, used at a rate of 0.1 to 0.5 per cent (0.1 to 0.5%) of the dry weight of the fibrous suspension.
9. The process according to claim 7 or 8, wherein the pulp used, which contains the filler, is diluted, after which the polymer is added as the main retention agent, a shearing stage is carried out, then the bentonite is added as the secondary retention agent, or the bentonite is replaced by kaolin as the secondary retention agent.
10. The process according to claim 9, wherein the shearing stage is carried out in a mixing pump or "fan pump".
11. The process according to claim 9 or 10, wherein the kaolin is pretreated with an electroyte.
12. The process according to any one of claims 9 to 11, wherein the quantity of branched polyacrylamide introduced either in reverse phase water-in-oil emulsion reversed in water or in a solution of the powder obtained by drying the emulsion, is between 0.03 and 1 %o, or between thirty and one thousand grams per ton (30 to 1,000 g/t) of dry pulp.
13. The process according to any one of claims 9 to 12, wherein the quantity of branched polyacrylamide introduced either in reverse phase water-in-oil emulsion inverted in water or in a solution of the powder obtained by drying the emulsion, is between 0.15 and 0.5 %o or between 150 and 500 g/t.
14. The process according to claim 12 or 13, wherein the branched polyacrylamide is a branched acrylic (co)polymer.
15. The process according to any of claims 1 to 14, wherein the branched polymer prepared in reverse phase emulsion is injected or introduced, before a shearing stage, into the paper pulp, which is more or less diluted according to the experience of one skilled in the art, and into the diluted paper pulp or "thin stock" diluted to about 0.7 - 1.5% solid matter.
16. The process according to claim 15, wherein the solid metter is selected from the group consisting of cellulose fibers, possible fillers and additives common in papermaking.
17. The process according to claim 15 or 16, wherein the branched polymer is injected or introduced either in emulsion reversed in water or in a solution of the powder obtained by drying the emulsion.
18. The process according to any of claims 1 to 17, wherein some of the branched polymer in emulsion is introduced at the level of the stage for preparing the "thick stock" with about 5%
or more solid matter, or even at the level of the preparation of the thick stock before a shearing stage.
or more solid matter, or even at the level of the preparation of the thick stock before a shearing stage.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9807144A FR2779452B1 (en) | 1998-06-04 | 1998-06-04 | PROCESS FOR PRODUCING PAPER AND CARDBOARD AND NOVEL RETENTION AND DRIPPING AGENTS THEREOF, AND PAPER AND CARDBOARD THUS OBTAINED |
| FR98/07144 | 1998-06-04 | ||
| PCT/FR1999/001278 WO1999063159A1 (en) | 1998-06-04 | 1999-06-01 | Method for making paper and cardboard and retention and dewatering agents |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2334196A1 CA2334196A1 (en) | 1999-12-09 |
| CA2334196C true CA2334196C (en) | 2008-07-15 |
Family
ID=9527102
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002334196A Expired - Lifetime CA2334196C (en) | 1998-06-04 | 1999-06-01 | Method for making paper and cardboard and retention and dewatering agents |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1092064B9 (en) |
| JP (1) | JP4699608B2 (en) |
| KR (1) | KR100685533B1 (en) |
| AT (1) | ATE254693T1 (en) |
| AU (1) | AU4043999A (en) |
| CA (1) | CA2334196C (en) |
| DE (1) | DE69912954T3 (en) |
| FR (1) | FR2779452B1 (en) |
| WO (1) | WO1999063159A1 (en) |
Families Citing this family (13)
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|---|---|---|---|---|
| FR2779752B1 (en) * | 1998-06-12 | 2000-08-11 | Snf Sa | PROCESS FOR PRODUCING PAPER AND CARDBOARD AND NOVEL RETENTION AGENTS THEREOF, AND PAPER AND CARDBOARD THUS OBTAINED |
| DE20220979U1 (en) | 2002-08-07 | 2004-10-14 | Basf Ag | Preparation of paper, pasteboard, or cardboard involving cutting of the paper pulp, addition of microparticles of cationic polymer, e.g. cationic polyamide, and a finely divided inorganic component after the last cutting step |
| MXPA04003942A (en) * | 2003-05-05 | 2007-06-29 | German Vergara Lopez | Retention and drainage system for the manufacturing of paper, paperboard and similar cellulosic products. |
| FR2869626A3 (en) * | 2004-04-29 | 2005-11-04 | Snf Sas Soc Par Actions Simpli | METHOD FOR MANUFACTURING PAPER AND CARDBOARD, NEW CORRESPONDING RETENTION AND DRAINING AGENTS, AND PAPERS AND CARTONS THUS OBTAINED |
| DE102004044379B4 (en) | 2004-09-10 | 2008-01-10 | Basf Ag | Process for the production of paper, paperboard and cardboard and use of a retention agent combination |
| DE102004063005A1 (en) | 2004-12-22 | 2006-07-13 | Basf Ag | Process for the production of paper, cardboard and cardboard |
| DE102008000811A1 (en) | 2007-03-29 | 2008-10-09 | Basf Se | Preparing paper, paperboard and cardboard, comprises shearing the paper material, adding ultrasound treated microparticle system and fine-particle inorganic component to the paper material and dewatering the paper material to form sheets |
| US8394237B2 (en) | 2008-09-02 | 2013-03-12 | BASF SE Ludwigshafen | Method for manufacturing paper, cardboard and paperboard using endo-beta-1,4-glucanases as dewatering means |
| EP2477708A4 (en) | 2009-09-15 | 2013-12-11 | Suncor Energy Inc | Process for flocculating and dewatering oil sand mature fine tailings |
| PL2477707T3 (en) | 2009-09-15 | 2017-10-31 | Suncor Energy Inc | Process for drying fine tailings |
| EP2493586A4 (en) | 2009-10-30 | 2014-07-23 | Suncor Energy Inc | Depositing and farming methods for drying oil sand mature fine tailings |
| EP2809845B1 (en) * | 2012-02-01 | 2019-01-16 | Basf Se | Process for the manufacture of paper and paperboard |
| GB2567456B (en) | 2017-10-12 | 2021-08-11 | Si Group Switzerland Chaa Gmbh | Antidegradant blend |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4617362A (en) * | 1984-12-31 | 1986-10-14 | Allied Corporation | Inverse emulsion polymers with improved incorporation of diallyldimethylammonium chloride |
| EP0201237B1 (en) † | 1985-04-25 | 1991-01-23 | Ciba Specialty Chemicals Water Treatments Limited | Flocculation processes |
| FR2589145A1 (en) * | 1985-10-25 | 1987-04-30 | Snf Sa | Flocculating agent for the treatment of sludges based on branched water-soluble addition polymers |
| GB8602121D0 (en) † | 1986-01-29 | 1986-03-05 | Allied Colloids Ltd | Paper & paper board |
| US5354481A (en) † | 1988-12-19 | 1994-10-11 | Cytec Technology Corp. | Water-soluble highly branched polymeric microparticles |
| ES2067517T5 (en) * | 1988-12-19 | 2004-09-16 | Cytec Technology Corp. | HIGH PERFORMANCE POLYMER FLOCULATING AGENTS. |
| US5405554A (en) † | 1990-02-08 | 1995-04-11 | Cytec Technology Corp. | High performance dewatering aids |
| US5234548A (en) * | 1992-01-02 | 1993-08-10 | Vinings Industries Inc. | Production of paper and paperboard |
| FR2692292B1 (en) * | 1992-06-11 | 1994-12-02 | Snf Sa | Method for manufacturing paper or cardboard with improved retention. |
| GB9313956D0 (en) * | 1993-07-06 | 1993-08-18 | Allied Colloids Ltd | Production of paper |
| GB9410920D0 (en) † | 1994-06-01 | 1994-07-20 | Allied Colloids Ltd | Manufacture of paper |
| FR2740482B1 (en) * | 1995-10-30 | 1997-11-21 | Snf Sa | PROCESS FOR IMPROVING RETENTION IN A PAPER, CARDBOARD AND THE LIKE PROCESS |
| SE9504081D0 (en) * | 1995-11-15 | 1995-11-15 | Eka Nobel Ab | A process for the production of paper |
| JP3614609B2 (en) * | 1996-09-10 | 2005-01-26 | ハイモ株式会社 | Papermaking chemicals, papermaking methods and methods for producing papermaking chemicals |
-
1998
- 1998-06-04 FR FR9807144A patent/FR2779452B1/en not_active Expired - Lifetime
-
1999
- 1999-06-01 AU AU40439/99A patent/AU4043999A/en not_active Abandoned
- 1999-06-01 KR KR1020007013706A patent/KR100685533B1/en not_active IP Right Cessation
- 1999-06-01 DE DE69912954T patent/DE69912954T3/en not_active Expired - Lifetime
- 1999-06-01 EP EP99923647A patent/EP1092064B9/en not_active Expired - Lifetime
- 1999-06-01 WO PCT/FR1999/001278 patent/WO1999063159A1/en active IP Right Grant
- 1999-06-01 CA CA002334196A patent/CA2334196C/en not_active Expired - Lifetime
- 1999-06-01 AT AT99923647T patent/ATE254693T1/en active
- 1999-06-01 JP JP2000552347A patent/JP4699608B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| KR20010052553A (en) | 2001-06-25 |
| JP4699608B2 (en) | 2011-06-15 |
| JP2002517626A (en) | 2002-06-18 |
| FR2779452A1 (en) | 1999-12-10 |
| ATE254693T1 (en) | 2003-12-15 |
| DE69912954T3 (en) | 2010-01-28 |
| AU4043999A (en) | 1999-12-20 |
| EP1092064B2 (en) | 2009-04-22 |
| WO1999063159A1 (en) | 1999-12-09 |
| KR100685533B1 (en) | 2007-02-22 |
| CA2334196A1 (en) | 1999-12-09 |
| EP1092064B9 (en) | 2009-10-21 |
| EP1092064B1 (en) | 2003-11-19 |
| DE69912954T2 (en) | 2004-11-11 |
| DE69912954D1 (en) | 2003-12-24 |
| EP1092064A1 (en) | 2001-04-18 |
| FR2779452B1 (en) | 2000-08-11 |
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