RU2243306C2 - Sized paper manufacture process - Google Patents

Abstract

FIELD: paper-and-pulp industry.

SUBSTANCE: process involves separately adding anionic or cationic sizing dispersion and sizing promoter to aqueous slurry containing cellulose fibers and optionally filler, said sizing promoter containing cationic organic polymer with one or several aromatic groups and anionic polymer with aromatic groups, which is stepped polymer, polysaccharide, and natural aromatic polymer.

EFFECT: improved sizing process.

31 cl, 6 tbl, 6 ex

Description

The present invention relates to a method for sizing paper, which comprises adding to a slurry containing cellulosic fibers and optional fillers, an anionic or cationic sizing dispersion and a sizing promoter containing a cationic organic polymer having one or more aromatic groups; as well as an anionic polymer comprising one or more aromatic groups, which is a step polymer, a polysaccharide and a natural aromatic polymer, molding and drying the resulting suspension, in which the dressing dispersion and dressing promoter are added separately to the aqueous suspension.

BACKGROUND OF THE INVENTION

Dispersions or emulsions of sizing agents are used in the manufacture of paper to give paper and paper board increased resistance to moisture and penetration of various liquids. Dressing dispersions are usually added to an aqueous suspension containing cellulosic fibers, optional fillers and various additives. The aqueous slurry is fed into a pressure vessel pushing the slurry onto a grid where a wet layer of paper forms. Subsequently, compounds such as starches and finely divided materials, which facilitate the dewatering of the suspension on a mesh, are typically added to the suspension. In the process of obtaining paper, water drained from the net and purified from the pulp, the so-called white water, is usually subjected to partial recirculation. The cellulosic suspension contains a certain amount of non-fibrous material, for example fillers, charged polymers, sizing agents and various charged contaminants, i.e. anionic waste, electrolytes, colloidal substances, etc. Non-fibrous material affects sizing efficiency, usually worsening it. A large number of charged compounds, for example, a high salt content in a suspension, results in a suspension that substantially complicates sizing, i.e. obtaining paper with satisfactory sizing properties. Other compounds contained in the sizing deteriorating suspension are various lipophilic, woody, extractable substances contained in recycled fibers and mechanical pulps. An increased amount of sizing agent added often improves sizing, but it causes an increase in cost, as well as an increased accumulation of sizing agents in water purified from the pulp. The accumulation of non-fibrous material, as well as any other component present in the suspension, is even more pronounced in mills in which the water purified from the pulp is actively recycled after only a small amount of fresh water is introduced into the paper production process. Thus, it is an object of the present invention to further improve sizing. Another objective of the present invention is to improve the sizing during sizing of aqueous, cellulosic suspensions having high conductivity and / or containing a large amount of lipophilic, woody, extractable substances. The following objectives will be listed below.

US patent 6001166 relates to aqueous dispersions of alkyl diketene containing cationic starch and anionic dispersants, such as ligninsulfonic acids, condensates of naphthalenesulfonic acid and formaldehyde.

WO 0023651 relates to anionic and cationic sizing dispersions containing ketene dimers and at least an anionic dispersing agent.

EP 984101 describes dressing compositions comprising ketene dimers or acid anhydrides and a complexing agent selected from aminopolycarboxylic acids, N-bis or tris - ((1.2-dicarboxyethoxy) ethyl) amines and phosphonic acids.

US 5,972,094 relates to sizing compositions comprising a thermoplastic resin selected from the group consisting of thermoplastic rosin, thermoplastic, hydrocarbon resins, thermoplastic polyamides and thermoplastic amide waxes.

US 5595629 describes a method of producing paper, including the formation of aqueous, pulp, paper pulp and adding cationic and anionic polymers to it to improve retention and / or drainage. The anionic polymer includes a formaldehyde condensate of a naphthalenesulfonic acid salt.

Description of the invention

It was found that this invention in accordance with the attached claims unexpectedly solves the problems indicated in the application. More specifically, this invention relates to a method of sizing paper, which comprises adding to an aqueous suspension containing cellulosic fibers and optional fillers, an anionic or cationic sizing dispersion and a sizing promoter containing a cationic organic polymer including one or more aromatic groups, and an anionic polymer, comprising one or more aromatic groups, which is a step polymer, polysaccharide or natural aromatic polymer, molding and drying the floor chennoy suspension, wherein the sizing dispersion and a sizing promoter is added to the aqueous suspension separately.

Sizing dispersion

The sizing agent contained in the anionic or cationic sizing dispersion used in the method according to the present invention is suitably any sizing agent with increased resistance to wetting and penetration of liquids, such as non-cellulose-reactive agents, including rosins, for example, enhanced and / or esterified rosins, waxes, fatty acids and derivatives of resin acid, for example fatty amides and fatty esters, for example, natural fatty glycerol triesters acids, and / or cellulose-reactive agents. The sizing dispersion preferably contains cellulose-reactive sizing agents. The cellulose-reactive sizing agents contained in the sizing dispersion may be selected from any cellulose-reactive agents known in the art. The sizing agent is suitably selected from hydrophobic ketene dimers, ketene multimers, acid anhydrides, organic isocyanates, carbamoyl chlorides and mixtures thereof, preferably ketene dimers and acid anhydrides. Ketene dimers suitably have the following general formula (I), in which R ¹ and R ² represent saturated or unsaturated hydrocarbon groups, typically saturated hydrocarbons, with hydrocarbon groups having suitably 8 to 36 carbon atoms, typically representing alkyl groups with a straight or branched chain having from 12 to 20 carbon atoms, such as hexadec or octadecyl groups. Ketene dimers can be liquid at ambient temperature, for example at 25 ° C, it is advisable at 20 ° C. Typically, acid anhydrides have the following general formula (II) below, in which R ³ and R ⁴ may be the same or different and represent saturated or unsaturated hydrocarbon groups, suitably having from 8 to 30 carbon atoms, or R ³ and R ⁴ together with the remainder —C — O — C— they can form a 5-6 membered ring, optionally further substituted with hydrocarbon groups having up to 30 carbon atoms. Examples of commercially available acid anhydrides include succinic alkyl and alkenyl anhydrides, as well as, in particular, isooctadecenyl succinic anhydride.

Suitable ketene dimers, acid anhydrides, and organic isocyanates include the compounds described in US Pat. No. 4,522,686, incorporated herein by reference.

Examples of suitable carbamoyl chlorides include the carbamoyl chlorides described in US patent No. 3887427, also included in the description by reference.

The method in accordance with the present invention includes adding to the suspension containing cellulosic fibers, anionic or cationic, aqueous, sizing dispersion, i.e. dispersing and / or stabilizing agents present in a dispersion, which may be called a “dispersing system”, have a common anionic or cationic charge, respectively. The dispersing system may include any agent that facilitates the formation of a dispersion or emulsion, such as dispersing and / or stabilizing agents, examples of which are polyelectrolytes, surfactants and electrolytes. Anionic, aqueous, sizing dispersions may include cationic compounds, i.e. cationic polyelectrolytes (cationic or amphoteric polyelectrolytes with a common cationic charge), and / or cationic surfactants, and / or any other cationic compound known to those skilled in the art, provided that the total charge of the dispersing system is anionic. On the other hand, cationic, aqueous, sizing dispersions may include anionic compounds, i.e. anionic polyelectrolytes (anionic or amphoteric polyelectrolytes with a common anionic charge), and / or anionic surfactants, and / or any other anionic compound known to those skilled in the art, provided that the total charge of the dispersing system is anionic. The anionic or cationic charge of the dressing dispersion can be determined using ZetaMaster S, PCS version.

According to a preferred embodiment of the present invention, the anionic or cationic sizing dispersion comprises a cationic organic polymer comprising one or more aromatic groups and / or an anionic polymer comprising one or more aromatic groups. The cationic organic polymer and the anionic polymer may be any of the polymers described below contained in the sizing promoter.

Anionic or cationic sizing dispersion added to the suspension may contain from 0.1 to 50% by weight of sizing agent based on the total weight of the dispersion / emulsion, more than 20% by weight of dispersions, including dressing agents from ketene dimer, may contain from 5 up to 50 wt.% ketene dimer based on the total weight of the dispersion, preferably 10 to 35 wt.% Dispersions or emulsions containing sizing agents from acid anhydrides may contain from 0.1 to 30 wt.% acid anhydrides based on the total weight of the dispersion / emulsion , it is advisable from 1 to 20 wt.% dispersion, soda chewing non-cellulose-reactive sizing agents suitably have a sizing agent content of 5 to 50 wt.%, preferably 10 to 35 wt.%. If the anionic and / or cationic polymer having one or more aromatic groups is contained in the sizing dispersion, they suitably present in an amount of approximately 0.1 wt.% to 15 wt.% by weight of the sizing agent.

The amount of sizing agent added to the aqueous suspension containing cellulosic fibers can be from 0.01 to 5 wt.%, It is advisable from 0.05 to 1.0 wt.% Based on the dry weight of cellulosic fibers and optional fillers, including in case the dose depends on the quality of the pulp or paper being dressed, the sizing agent and the degree of sizing.

According to the present invention, an anionic or cationic sizing dispersion and a sizing promoter comprising a cationic organic polymer including one or more aromatic groups, and an anionic polymer including one or more aromatic groups, which is a step polymer, polysaccharide or natural aromatic polymer, are added to water suspension separately. Although the sizing dispersion may contain the same polymers as the sizing promoter, a significant improvement in sizing is observed only if the sizing promoter and sizing dispersion are added separately to the cellulosic suspension. Separate addition means that the sizing dispersion, which may include any sizing promoter polymers, and the sizing promoter are added to the cellulosic suspension (liquid mass) in different places, or essentially in one place, but at different times. Moreover, the cationic organic polymer and the anionic polymer forming the sizing promoter are also advantageously added separately. The anionic polymer is preferably added to the slurry after the addition of both the dressing dispersion and the cationic organic polymer.

According to a preferred embodiment of the present invention, a paper sizing method comprises adding to an aqueous suspension containing cellulosic fibers and optional fillers an anionic or cationic sizing dispersion containing a sizing agent and an anionic polymer comprising one or more aromatic groups, which is a step polymer, a polysaccharide or a natural aromatic polymer, the amount of sizing agent added to the suspension being approximately but from 0.01 to 5.0 wt.% based on the weight of dry fibers; and a dressing promoter containing a cationic polymer comprising one or more aromatic groups, suitably a cationic polysaccharide or cationic vinyladditive polymer, and an anionic polymer comprising one or more aromatic groups, representing a step polymer, polysaccharide or natural aromatic polymer, wherein cationic polymer added to the suspension is from about 0.001 to 3 wt.% based on the weight of dry fibers, and the amount of anionic poly the measure added to the suspension is from about 0.001 to 3% by weight, based on the weight of dry fibers; molding and drying the resulting suspension, in which the dressing dispersion and the dressing promoter are added separately to the aqueous suspension.

According to a further preferred embodiment of the invention, the anionic or cationic sizing dispersion comprises a sizing agent, a cationic organic polymer comprising one or more aromatic groups, such as a cationic polysaccharide or cationic vinyladditive polymer, and an anionic polymer comprising one or more aromatic groups representing a step polymer, a polysaccharide or a natural aromatic polymer, it is advisable to anionic polymer, which is a step polymer or natural aromatic polymer.

The cationic polymer comprising one or more aromatic groups is suitably a cationic polysaccharide having the structural formula (I):

in which P represents a polysaccharide residue; A represents a chain of atoms comprising C and H atoms that secure the N to the polysaccharide residue, each of R ₁ and R ₂ represents H or a hydrocarbon group, R ₃ represents an aromatic hydrocarbon group, n is an integer from 2 to 300,000, and X ^- represents anionic counterion; or a vinyladditive polymer obtained by polymerization of a cationic monomer or a mixture of monomers, including a cationic monomer represented by the general formula (II):

in which R ₁ represents H or CH ₃ ; each of R ₂ and R ₃ represents an alkyl group having from 1 to 3 carbon atoms, A ₁ represents O or NH, B ₁ represents an alkylene group having from 2 to 8 carbon atoms, or a hydroxypropylene group, Q represents a substituent containing an aromatic group, and X - represents an anionic counterion. More preferably, the cationic polymer comprising one or more aromatic groups is a cationic polysaccharide having the structural formula (I):

in which P represents a polysaccharide residue; A represents a chain of atoms comprising C and H atoms attaching N to the polysaccharide residue, each of R ₁ and R ₂ represents H or a hydrocarbon group, R ₃ represents an aromatic hydrocarbon group, n is an integer from 2 to 300,000, and X ^- represents anionic counterion.

Cationic organic polymer comprising one or more aromatic groups

The cationic, organic polymer sizing promoter polymer suitably present in the sizing dispersion can be obtained from natural or synthetic sources and can be linear, branched or cross-linked. The cationic polymer may preferably be soluble or dispersible in water. Examples of suitable cationic polymers include cationic polysaccharides, for example starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins, preferably starches and guar gums, while suitable starches include potato starches corn, wheat, tapioca, rice, waxy maize, oats, etc .; cationic, synthetic organic polymers, such as cationic increasing chain polymers, for example cationic vinyladditive polymers, such as acrylate, acrylamide and vinylamide based polymers, as well as cationic, step polymers, for example cationic polyurethanes. Particularly preferred are cationic, organic polymers selected from polysaccharides, i.e. starches, and cationic, vinyladditive polymers, such as acrylamide-based polymers containing an aromatic group.

The aromatic group of the cationic, organic polymer may be present in the polymer base or in a substituent group attached to its base (main chain), preferably in a substituent group. Examples of suitable aromatic groups include aryl, aralk or alkaryl groups, for example phenyl, phenylene, naphthyl, xylylene, benzyl and phenylethyl; preferably benzyl, nitrogen-containing, aromatic (aryl) groups, for example pyridinium and quinolinium, as well as derivatives of these groups. Examples of cationically charged groups that may be present in the cationic polymer, as well as in the monomers used to produce the cationic polymer, include quaternary ammonium groups, tertiary amino groups and their acid addition salts.

In a preferred embodiment, the cationic organic polymer containing an aromatic group is selected from cationic polysaccharides. The aromatic group of the polysaccharide can be attached to a heteroatom, for example nitrogen or oxygen, present in the polysaccharide, the heteroatom being optionally charged, for example, when it is nitrogen. The aromatic group can also be attached to a group comprising a heteroatom, for example, an amide, ester or ether, while these groups can be attached to the polysaccharide base (main chain), for example, through a chain of atoms. Examples of suitable aromatic groups and groups including an aromatic group include aryl and aralkyl groups, for example phenyl, phenylene, naphthyl, xylylene, benzyl and phenylethyl; nitrogen-containing, aromatic (aryl) groups, for example pyridinium and quinolinium, as well as derivatives of these groups in which one or more substituents attached to said aromatic groups can be selected from hydroxyl, halo, for example chloride, nitro, and hydrocarbon groups having from 1 to 4 carbon atoms.

The cationic, organic polymer is preferably selected from cationic polysaccharides having the general structural formula (I):

in which P represents a polysaccharide residue; A represents a group, attaching N to the polysaccharide residue, it is advisable, atomic chains including C and H atoms, and, optionally, O and / or N atoms, typically an alkylene group having from 2 to 18, suitably from 2 to 8 atoms carbon optionally interrupted or substituted with one or more heteroatoms, for example, O or N, for example, an alkyleneoxy group or a hydroxypropylene group (—CH ₂ —CH (OH) —CH ₂ -); each of R ₁ and R ₂ represents H or, preferably, a hydrocarbon group, suitably alkyl having from 1 to 3 carbon atoms, suitably from 1 to 2 carbon atoms; R ₃ expediently represents an aromatic hydrocarbon group including aralkyl groups, for example benzyl and phenylethyl groups; n is an integer from about 2 to 300,000, suitably from 5 to 200,000, and preferably from 6 to 125,000, or, alternatively, R ₁ , R ₂ and R ₃ together with N form an aromatic group containing from 5 to 12 carbon atoms; and X ^- represents an anionic counterion, usually a halogen, such as chloride.

The cationic polysaccharide modified with an aromatic group may have a wide range of degree of substitution; the degree of cationic substitution (DS _c ) may be from 0.01 to 0.5, suitably from 0.02 to 0.3, preferably from 0.025 to 0.2; the degree of aromatic substitution (DS _Ar ) can be from 0.01 to 0.5, suitably from 0.02 to 0.3, preferably from 0.025 to 0.2, and the degree of anionic substitution (DS _A ) can be from 0 to 0 , 2, it is advisable from 0 to 0.1, preferably from 0 to 0.05.

, 41(1989), No. 5, pp. 192-196, содержание которых включено в данное описание в качестве ссылки.Polysaccharides can be obtained by cationic and aromatic modification of a polysaccharide in a known manner using one or more agents containing a cationic and / or aromatic group, for example, by reacting an agent with a polysaccharide in the presence of an alkaline substance such as an alkali metal or alkaline earth metal hydroxide. The polysaccharide subjected to cationic and aromatic modifications may be nonionic, anionic, amphoteric or cationic. Suitable modifying agents include non-ionic agents, such as, for example, aralkyl halides, for example benzyl chloride and benzyl bromide; reaction products of epichlorohydrin and dialkylamines having at least one substituent comprising the aforementioned aromatic group, including 3-dialkylamino-1,2-epoxypropanes; and cationic agents, such as, for example, the reaction product of epichlorohydrin and tertiary amines having at least one substituent containing the above aromatic group, including alkaryl dialkylamines, for example dimethylbenzylamine; arylamines, for example pyridine and quinoline. Suitable cationic agents of this type include 2,3-epoxypropyltrialkylammonium halides and halohydroxypropyltrialkylammonium halides, for example N- (3-chloro-2-hydroxypropyl) -N- (hydrophobic alkyl) -N, N-di (lower alkyl) ammonium chloride and chloride N-glycidyl-N- (hydrophobic alkyl) -N, N-di (lower alkyl) ammonium, in which the aromatic group is the same as above, especially octyl, decyl and dodecyl, and the lower alkyl is methyl or ethyl; halohydroxypropyl-N, N-dialkyl-N-alkarylammonium halides and N-glycidyl-N- (alkaryl) -N, N-dialkylammonium chloride, for example, N- (3-chloro-2-hydroxypropyl) -N- (alkaryl) chloride -N, N-di (lower alkyl) ammonium, in which the alkaryl and lower alkyl groups are the same as above, in particular N- (3-chloro-2-hydroxypropyl) -N-benzyl-N, N- dimethylammonium; and also N– (3-chloro-2-hydroxypropyl) pyridinium chloride. In general, when using a non-ionic aromatic agent, the polysaccharide is expediently converted to a cationic polysaccharide using any of the cationic agents known in the art before or after hydrophobic modification. Examples of suitable cationic and / or aromatic modifying agents modified with aromatic groups of polysaccharides, and methods for their preparation are described in US patent No. 4687519 and 5463127; in International Publication WO 94/24169, in European Patent No. 189935; and in the publication SPPatel, RGPatel and VSPatel, Starch /

, 41 (1989), No. 5, pp. 192-196, the contents of which are incorporated into this description by reference.

In accordance with yet another preferred embodiment, the cationic, organic polymer is selected from homopolymers and copolymers derived from one or more monomers comprising at least one monomer having an aromatic group, suitably an ethylenically unsaturated monomer. The synthetic polymer may be branched linear or branched. The aromatic group of the synthetic polymer may be present in the polymer base or, preferably, it may be a side group attached to or continuing from the polymer base, or present in a side group attached to or continuing from the polymer base. Suitable aromatic (aryl) groups include groups containing an optionally substituted phenyl group, an optionally substituted phenylene group, and an optionally substituted naphthyl group, for example, groups having the general formulas —C ₆ H ₅ , —C ₆ H ₄ -, —C ₆ H ₃ - and –C ₆ H ₂ -, for example, in the form of phenylene (-C ₆ H ₄ -), xylylene (-CH ₂ -C ₆ H ₄ -CH ₂ -), phenyl (-C ₆ H ₅ ), benzyl (- CH ₂ -C ₆ H ₅ ), phenethyl (-CH ₂ CH ₂ -C ₆ H ₅ ) and substituted phenyl (for example, -C ₆ H ₄ -Y, -C ₆ H ₃ Y ₂ and –C ₆ H ₂ Y ₃₎ in which one or more substituents (Y), attached to the phenyl ring can be shaven s from hydroxyl, halogens, such as chloride, nitro, and hydrocarbon groups having from 1 to 4 carbon atoms.

The cationic polymer is preferably a vinyladditive polymer. The term “vinyladditive polymer” as used herein means a polymer obtained by the additive polymerization of one or more vinyl monomers or ethylenically unsaturated monomers, including, for example, acrylamide and acrylate based monomers. The cationic polymer is suitably selected from cationic, vinyladditive polymers obtained by polymerization of a cationic monomer or a mixture of monomers comprising a cationic monomer represented by the general formula (II):

in which R ₁ represents H or CH ₃ ; each of R ₂ and R ₃ preferably represents an alkyl group having from 1 to 3 carbon atoms, typically from 1 to 2 carbon atoms; A ₁ represents O or NH; B ₁ represents an alkylene group having from 2 to 8 carbon atoms, suitably from 2 to 4 carbon atoms, or a hydroxypropylene group; Q represents a substituent containing an aromatic group, suitably a phenyl or substituted phenyl group, which can be attached to nitrogen using an alkylene group usually having from 1 to 3 carbon atoms, suitably from 1 to 2 carbon atoms, preferably Q represents benzyl a group (—CH ₂ —C ₆ H ₅ ); and X ^- represents an anionic counterion, usually a halogen, such as chloride. Examples of suitable monomers represented by general formula (II) include quaternary monomers obtained by treating with benzyl chloride dialkylaminoalkyl (meth) acrylates, for example dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and dimethylaminohydroxypropyl (meth) acrylamino and acrylamides, for example, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide. Preferred cationic monomers of the general formula (II) include the quaternary salts of dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate benzyl chloride.

The cationic, vinyladditive (synthetic, cationic) polymer may be a homopolymer obtained from a cationic monomer including an aromatic group, or a copolymer obtained from a mixture of monomers containing a cationic monomer including an aromatic group and one or more copolymerizable monomers. Suitable copolymerizable, nonionic monomers include monomers represented by the general formula (III):

in which R ₄ represents H or CH ₃ ; each of R ₅ and R ₆ represents H or a hydrocarbon group, suitably alkyl having from 1 to 6, suitably from 1 to 4, and typically from 1 to 2 carbon atoms; A ₂ represents O or NH; B ₂ represents an alkylene group having from 2 to 8 carbon atoms, suitably from 2 to 4 carbon atoms, or a hydroxypropylene group, or, alternatively, both A and B do not represent anything in the presence of a simple bond between C and N (O = C- NR ₅ R ₆ ). Examples of suitable copolymerizable monomers of this type include (meth) acrylamide; acrylamide-based monomers such as N-alkyl (meth) acrylamides and N, N-dialkyl (meth) acrylamides, for example N-n-propylacrylamide, N-isopropyl (meth) acrylamide, N-n-butyl (meth) acrylamide N-isobutyl (meth) acrylamide and N-tert-butyl (meth) acrylamide; and dialkylaminoalkyl (meth) acrylamides, for example dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide; acrylate-based monomers such as dialkylaminoalkyl (meth) acrylates, for example dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate and dimethylaminohydroxypropyl acrylate; as well as vinylamides, for example, N-vinylformamide and N-vinylacetamide. Preferred copolymerizable, nonionic monomers include acrylamide and methacrylamide, i.e. (meth) acrylamide, wherein the base polymer is preferably an acrylamide-based polymer.

Suitable copolymerizable cationic monomers include monomers represented by the general formula (IV):

in which R ₇ represents H or CH ₃ ; each of R ₈ , R ₉ and R ₁₀ represents H or, preferably, a hydrocarbon group, suitably alkyl having from 1 to 3 carbon atoms, usually from 1 to 2 carbon atoms; A ₃ represents O or NH; B ₃ represents an alkylene group having 2 to 4 carbon atoms, suitably from 2 to 4 carbon atoms or gidroksipropilengruppu and X (?) ^- is an anionic counterion, usually methylsulphate or a halide like chloride. Examples of suitable cationic copolymerizable monomers include acid addition salts and quaternary ammonium salts of the above dialkylaminoalkyl (meth) acrylates and dialkylaminoalkyl (meth) acrylamides, usually prepared using acids such as Hcl, H ₂ SO ₄ , etc., or quaternizing agents such as methyl chloride, dimethyl sulfate, etc .; as well as diallyldimethylammonium chloride. Preferred copolymerizable, cationic monomers include a dimethylaminoethyl (meth) acrylate methyl chloride quaternary salt and diallyldimethylammonium chloride. Copolymerizable, anionic monomers such as acrylic acid, methacrylic acid, various sulfonated vinyladditive monomers can also be used, preferably in small amounts.

The cationic vinyladditive polymer can be obtained from a mixture of monomers, usually containing from 1 to 99 mol%, preferably from 2 to 50 mol%, preferably from 5 to 20 mol%, of a cationic monomer comprising an aromatic group, preferably represented by the general formula ( II), and from 99 to 1 mol%, it is advisable from 98 to 50 mol%, preferably from 95 to 80 mol%, of other copolymerizable monomers, preferably including acrylamide or methacrylamide ((meth) acrylamide), wherein the mixture of monomers expediently includes from 98 to 50 mol%, preferably from 95 to 80 mol%, (meth) acrylamide, and the sum of percentages is 100.

The cationic polymer can also be selected from polymers resulting from the condensation reaction of one or more monomers containing an aromatic group. Examples of such monomers include toluene diisocyanates, bisphenol A, phthalic acid, phthalic anhydride, etc., which can be used to prepare cationic polyurethanes, cationic polyamidamines, etc.

Alternatively, the cationic polymer may be a polymer undergoing aromatic modification using an aromatic group containing agent. Suitable modifying agents of this type include benzyl chloride, benzyl bromide, N- (3-chloro-2-hydroxypropyl) -N-benzyl-N, N-dimethylammonium chloride and N– (3-chloro-2-hydroxypropyl) pyridinium chloride. Suitable polymers for such an aromatic modification include vinyladditive polymers. If the polymer contains tertiary nitrogen, which can be quaternized with a modifying agent, the use of such agents usually leads to the polymer becoming cationic. Alternatively, the polymer undergoing aromatic modification may be cationic, for example, a cationic, vinyladditive polymer.

Typically, the charge density of the cationic polymer is from 0.1 to 6.0 meq / g of dry polymer, suitably from 0.2 to 4.0, and preferably from 0.5 to 3.0.

The weight average molecular weight of the synthetic polymers is usually at least about 500,000, suitably more than about 1,000,000, and preferably more than about 2,000,000. The upper bound does not matter; it may be approximately 50,000,000, usually 30,000,000, and, expediently, 2,500,000.

Anionic polymer including one

or several aromatic groups

An anionic polymer comprising an aromatic group contained in a sizing promoter and optionally contained in a sizing dispersion according to the present invention is a step polymer, polysaccharide or natural aromatic polymer. The term “stepwise polymer” in this description means a polymer obtained by stepwise polymerization, as well as a polymer resulting from a stepwise reaction and stepwise polymerization, respectively. The anionic polymer contained in the promoter is preferably a step polymer, a polysaccharide or a natural aromatic polymer, provided that the anionic polymer is not a polymer obtained by condensation of melaminesulfonic acid. The anionic polymer may be a step polymer or a natural, aromatic polymer. Anionic polymers in accordance with this invention can be linear, branched or cross-linked. Anionic polymer, as a rule, can be water-soluble or water-dispersible. The anionic polymer is preferably organic. Preferred anionic, aromatic polymers are those obtained by condensation of naphthalenesulfonate, such as condensed naphthalenesulfonate, as well as modified lignin polymers, such as ligninsulfonate.

The aromatic group of the anionic polymer may be present in the polymer base or in a substituent group attached to the polymer base (main chain). Examples of suitable aromatic groups include aryl, aralk or alkaryl groups, as well as derivatives thereof, for example phenyl, tolyl, naphthyl, phenylene, xylylene, benzyl, phenylethyl and derivatives of these groups. Examples of anionically charged groups that may be present in anionic polymers, as well as in monomers used to produce an anionic polymer, include groups carrying an anionic charge and acid groups carrying an anionic charge after dissolution or dispersion in water, while these groups in this the description is generally regarded as anionic groups such as phosphate, phosphonate, sulfate, sulfonic acid, sulfonate, carboxylic acid, carboxylate, alcoholate and phenolic groups, i.e. hydroxy substituted phenyls and naphthyls. Anionic charge groups are typically alkali metal, alkaline earth metal or ammonium salts.

Examples of suitable anionic step polymerization products in accordance with the present invention include condensation polymers, i.e. polymers resulting from stepwise condensation polymerization, for example, aldehyde condensates such as formaldehyde with one or more aromatic compounds containing one or more anionic groups, especially condensed polymers such as naphthalenesulfonate, and, optionally, other comonomers that can be used during condensation polymerization, such as urea. Examples of suitable aromatic compounds containing anionic groups include phenol and naphthol compounds, such as phenol, naphthol, resorcinol and their derivatives, aromatic acids and their salts, such as phenyl, phenolic, naphthyl and naphthol acids and salts, typically sulfonic acids and sulfonates, for example, benzenesulfonic acid and sulfonate, xylene sulfonic acid and sulfonates, naphthalenesulfonic acid and sulfonate, phenolsulfonic acid and sulfonate.

Examples of further suitable anionic step polymerization products in accordance with the present invention include additive polymers, i.e. Additive polymerization polymers, for example, anionic polyurethanes derived from a mixture of monomers, including aromatic isocyanates and / or aromatic alcohols. Examples of suitable aromatic isocyanates include diisocyanates, for example, toluene-2,4- and 2,6-diisocyanates and diphenylmethane-4,4′-diisocyanate. Examples of suitable aromatic alcohols include dihydric alcohols, i.e. diols, for example, bisphenol A, phenyldiethanolamine, glycerol monoterephthalate and trimethylolpropane monoterephthalate. Monohydric aromatic alcohols such as phenol and its derivatives can also be used. The mixture of monomers may also contain non-aromatic isocyanates and / or alcohols, typically diisocyanates and diols, for example, any of them that are known to be used in the preparation of polyurethanes. Examples of suitable monomers including anionic groups include monoester reaction products of triols, for example, trimethylol ethane, trimethylolpropane and glycerol, with dicarboxylic acids or their anhydrides, for example succinic acid and anhydride, terephthalic acid and anhydride such as glycerol monosuccinate, glycerol monosuccinate, mono-succinate, trimethylolpropane, trimethylolpropane monoterephthalate, N, N-bis- (hydroxyethyl) -glycine, di- (hydroxymethyl) propionic acid, N, N-bis- (hydroxyethyl) -2-aminoethanesulfonic acid and the like, optionally and usually in combination with reaction with a base such as alkali metal and alkaline earth metal hydroxides, for example sodium hydroxide, ammonia or an amine, for example triethylamine, to thereby obtain an alkali metal counterion , alkaline earth metal or ammonium.

Examples of suitable anionic step polymerization products in accordance with this invention include anionic, vinyladditive polymers derived from a mixture of vinyl or ethylenically unsaturated monomers comprising at least one monomer having an aromatic group and at least one monomer having an anion group typically copolymerized with nonionic monomers such as acrylate and acrylamide monomers. Examples of suitable anionic monomers include (meth) acrylic acid and paravinyl phenol (hydroxystyrene).

Examples of suitable anionic polysaccharides include starches, guar gums, celluloses, chitins, chitosans, glycans, galactans, glucans, xanthan gums, pectins, mannans, dextrins, preferably starches, guar gums and cellulose derivatives, suitably starches, potato starches corn, wheat, tapioca, rice, waxy maize and oats, preferably potato starch. The anionic groups in the polysaccharide can be native and / or introduced by chemical methods known in the art.

Examples of suitable (modified) natural, aromatic, anionic polymers in accordance with this invention include Kraft lignin, such as modified lignin polymers, for example, lignin adducts copolymerized with formaldehyde, and sulfonated lignin, for example, extracts of ligninsulfonate and tannin, i.e. . natural polyphenolic substances present in the organic extracts of the bark of some wood species.

An anionic polymer containing an aromatic group is suitably selected from step polymers, polysaccharides and a natural aromatic polymer. Preferred are polymers such as condensed naphthalenesulfonate and modified lignin polymers such as ligninsulfonates.

The weight average molecular weight of the anionic polymer can vary over a wide range depending, inter alia, on the type of polymer used; it is usually at least about 500, suitably higher than about 2000, and preferably higher than about 5000. The upper limit does not matter; it may be approximately 2,000,000,000, typically 150,000,000, suitably 1,000,000,000 and preferably 1,000,000.

The anionic polymer can have a wide range of degree of anionic substitution (DS _A ) depending, inter alia, on the type of polymer used; DS _{A is} usually from 0.01 to 2.0, suitably from 0.02 to 1.8, and preferably from 0.025 to 1.5; and the degree of aromatic substitution (DS _Q ) can be from 0.001 to 1.0, typically from 0.01 to 0.8, suitably from 0.02 to 0.7, and preferably from 0.025 to 0.5. If the anionic polymer includes cationic groups, the degree of cationic substitution (DS _c ) may be, for example, from 0 to 0.2, suitably from 0 to 0.1, and preferably from 0 to 0.05, with the anionic polymer has a common anionic charge. The anionic charge density of the anionic polymer is usually from 0.1 to 6.0 meq / g of dry polymer, suitably from 0.5 to 5.0, and preferably from 1.0 to 4.0.

The cationic organic polymer comprising the aromatic group and the anionic polymer including the aromatic group of the dressing promoter can be added to the aqueous suspension (feed) in any order separately from the dressing dispersion and in an amount that can vary widely, depending on, inter alia , on the type of raw material, salt content, type of salts, filler content, type of filler, place of addition, etc. In general, polymers are added in an amount that provides better sizing than sizing obtained without adding them, while typically a cationic organic polymer is added to the feed before adding the anionic polymer. The cationic polymer is usually added in an amount of at least 0.001 wt.%, Often at least 0.005 wt.%, Based on the dry weight of the feed, while the upper limit is usually 3 wt.%, 2.0 wt. .% Anionic polymer is usually added in an amount of at least 0.001 wt.%, Often at least 0.005 wt.%, Calculated on the dry weight of the feed, while the upper limit is usually 3 wt.% 1.5% by weight is advisable

In addition to the cationic organic polymer and the anionic polymer, the sizing promoter may contain other compounds that improve sizing efficiency, such as anionic micronized materials, for example particles based on silicon dioxide and clay like smectite, cationic organic polymers with a low molecular weight, aluminum compounds, such as aluminum alum, aluminates, aluminum chloride, aluminum nitrate, and also polyaluminium compounds such as polyaluminium chlorides, polyaluminium sulfates, polyaluminium compounds They contain ions of both chloride and sulfate, polyaluminium silicates, sulfates and their mixtures, anionic vinyladditive polymers and their combinations.

The method in accordance with this invention is preferably used to obtain paper from suspension containing cellulose fibers, as well as additional fillers having high conductivity. Typically, the conductivity of the feed is at least 0.20 mS / cm, suitably at least 0.5 mS / cm, preferably at least 3.5 mS / cm. Very good sizing results are observed at a conductivity level above 5.0 mS / cm and even above 7.5 mS / cm. Conductivity can be measured using standard equipment, such as, for example, the WTW LF 539 manufactured by Christian Berner. The above values are expediently determined by measuring the conductivity of the cellulosic suspension supplied to or in the pressure vessel of the paper machine, or, alternatively, by measuring the conductivity of the pulp-free water resulting from the dehydration of the suspension. A high level of conductivity means a high salt content (electrolytes), while various salts can be based on mono-, bi- and polyvalent cations, such as alkali metals, for example, Na ⁺ and K ⁺ , alkaline earth metals, for example, Ca ²⁺ and Mg ²⁺ , aluminum ions, for example, Al ³⁺ , Al (OH) ²⁺ , and polyaluminium ions, as well as mono-, di- and multivalent anions, such as halides, for example, Cl ^- , sulfates, for example, SO $\genfrac{}{}{0ex}{}{\text{-2}}{\text{4}}$ and НСО $\genfrac{}{}{0ex}{}{\text{-}}{\text{4}}$ carbonates, e.g. CO $\genfrac{}{}{0ex}{}{\text{2}}{\text{3}}$ and NSO $\genfrac{}{}{0ex}{}{\text{-}}{\text{3}}$ , silicates and lower organic acids. This invention is particularly applicable in the manufacture of paper from raw materials with a high content of salts or divalent and multivalent cations; as a rule, the cation content is at least 200 ppm, it is advisable to at least 300 ppm, and preferably at least 400 ppm Salts can be obtained from cellulosic fibers and fillers used to produce raw materials, in particular in connected mills, in which a concentrated aqueous suspension of fibers from a cellulose mill is usually mixed with water to obtain a diluted suspension suitable for making paper in a paper mill. Salt can also be obtained from various additives introduced into the raw material, from fresh water supplied during the process, or added specially, etc. In addition, the salt content is usually higher in those processes in which purified water from the pulp is actively recycled, which can lead to a significant accumulation of salts in the water circulating in the process.

The present invention also relates to methods for producing paper in which purified water from the pulp is intensively recycled (recycled), i.e. with a high degree of cyclization of the water purified from the pulp, for example, using from 0 to 30 tons of fresh water per ton of dry paper obtained, typically less than 20, expediently less than 15, preferably less than 10, and especially less than 5 tons of fresh water per ton of paper. Recycling the water purified from the pulp resulting from the application of the method expediently includes mixing said water with cellulosic fibers and / or optional fillers to obtain a dressing slurry; it preferably includes mixing the pulp-free water with a slurry containing cellulosic fibers and optional fillers prior to feeding the slurry onto a sizing sizing grid.

Additional additives commonly used in the manufacture of paper, such as, for example, additional agents providing strength in the dry and wet state, of course, can be used in combination with the additives in accordance with this invention. The cellulosic suspension or feed may also contain conventional mineral fillers, such as, for example, kaolin, white clay, titanium dioxide, gypsum, talc, as well as natural and synthetic calcium carbonates, such as chalk, ground marble and precipitated calcium carbonate.

The method in accordance with this invention is used to obtain paper. The term “paper” in this description, of course, means not only paper and its receipt, but also other sheet or film products, such as, for example, cardboard and paper cardboard, as well as their receipt. This method can be used to obtain paper from various types of suspensions of cellulose-containing fibers, while these suspensions should contain at least 25 wt.%, Preferably at least 50 wt.%, Of such fibers based on dry weight substance. Suspension may be based on fibers from chemical cellulose, such as sulphate, sulphite and organosolv cellulose, wood pulp, such as thermal wood pulp, chemical thermal wood pulp, enriched cellulose and pulp from ground wood, both hard and soft; as well as recycled fibers, optionally derived from recycled cellulose and mixtures thereof. The present invention is particularly applicable to the production of paper from cellulose-based suspensions, including recycled fibers and recycled cellulose, while the content of cellulose fibers of this origin can be up to 100%, suitably from 20 to 100%.

The invention is further illustrated by the following examples, which, however, are not intended to be limiting. Fractions and% mean mass fractions and%, respectively, unless otherwise indicated.

In all of the examples below, the sizing dispersion and sizing promoter are added separately to the cellulosic suspension. Moreover, if the promoter contains more than one polymer including an aromatic group, then such polymers are added to the suspension separately relative to each other and to the dispersion.

Example 1

The effectiveness of the sizing method is determined using the test 60 sbb, (table 1).

An anionic sizing dispersion is obtained containing dimeralkyl ketene, condensed naphthalenesulfonate and dimethylammonium di (hydrogenated solid fat). The sizing dispersion contains 30% AKD, 4% di (hydrogenated solid fat) dimethylammonium chloride and 6% AKD-based condensed naphthalenesulfonate. The sizing dispersion is added to the feed in an amount of 5 kg AKD per tonne of dry feed.

In test 2, the sizing promoter contains condensed naphthalenesulfonate (sold under the trademark Tamol®) and cationic starch with a cationic substitution DS of 0.065 with respect to nitrogen containing benzyl groups. In test 1, cationic starch without aromatic groups with a cationic substitution of 0.065 and particles of anionic, inorganic silicon dioxide used in the form of a sol, i.e. anionic, non-aromatic polymer.

The basis of the used roll charging is 80 wt.% Sulphate pulp from bleached birch / pine wood (60/40) and 20 wt.% CaCO ₃ , purified to 200 CSF and containing 0.3 g / l of raw material Na ₂ SO ₄ having conductivity equal to 461 μS / cm and a pH of 8.1.

Example 2

The sizing efficiency of the method is determined (cobb test 60) (see table 2) by adding the same anionic sizing dispersion as in Example 1 and a sizing promoter containing cationic starch with a cationic substitution DS of 0.065 with respect to nitrogen, including benzyl groups and particles of anionic, inorganic silicon dioxide (test 1); and a promoter containing condensed naphthalenesulfonate (sold under the trademark Tamol®) and cationic starch with a cationic substitution DS of 0.065 relative to nitrogen containing benzyl groups (test 2). However, calcium chloride is added to the roll charge to achieve a conductivity of 5000 μS / cm, thereby simulating a roll charge having a high conductivity.

Example 3

The sizing efficiency is determined using a cationic sizing dispersion containing 15% alkyl ketene dimer, 2% cationic starch and 0.6% AKD-based sodium lignosulfonate. The components and the added amount of components contained in the sizing promoter shown in Table 3 include fused naphthalene sulfonate, cationic starch with aromatic groups having a DS of 0.065, and cationic starch including aromatic groups having a DS of 0.065 and anionic, inorganic particles of silicon oxide, used in the form of sol. The same raw materials are used as in Example 2, having a pH of 8.1 and a conductivity of 5000 μS / cm, obtained by adding calcium chloride to the raw materials.

Example 4

An anionic sizing dispersion is obtained containing 8.9% of a commercial alkyl ketene dimer, 0.89% of aromatic, substituted, cationic starch having a DS of 0.065 and containing benzyl groups, and 0.22% of condensed naphthalenesulfonate sold under the trademark Tamol® . An anionic dispersion in an amount of 0.0115% (calculated on dry matter) based on ketene dimer is added to a cellulosic suspension (calculated on dry matter) containing 30% pine wood, 30 wt.%, 40% eucalyptus and 15% precipitated CaCO ₃ . The conductivity of the suspension is 500 μS / cm. A dressing promoter containing benzyl substituted starch having a DS of 0.065 and condensed naphthalene sulfonate sold under the trademark Tamol® (test 2) is also added to the suspension.

The same anionic dispersion is also added to the same suspension. However, the sizing promoter added to the suspension does not contain aromatic polymers. The sizing promoter contains cationic starch with a DS of 0.065, which does not include aromatic groups and anionic, inorganic silica particles used in the form of sol (test 1). The number of polymers of the promoter and sizing agent (AKD) of the dispersion are shown in table 4.

Example 5

In this example, the same dispersion and dressing promoters are used as in Example 2, except that the conductivity of the suspension is 5000 μS / cm.

The number of polymers of the promoter and sizing agent (AKD) of the dispersion are shown in table 5.

Example 6

The effectiveness of the sizing method is determined using the test 60 Sobb. An anionic sizing dispersion is obtained containing an alkyl ketene dimer, condensed naphthalenesulfonate and dimethylammonium di (hydrogenated solid fat). The sizing dispersion contains 30% AKD, 4% di (hydrogenated solid fat) dimethylammonium chloride and 6% AKD-based condensed naphthalenesulfonate. The sizing dispersion is added to the feed in an amount of 0.3 kg AKD per tonne of dry feed.

Cationic starch with a cationic substitution DS equal to 0.065 with respect to nitrogen containing benzyl groups and starch with a cationic substitution DS equal to 0.065 are used in combination with condensed naphthalenesulfonate and melaminesulfonate, respectively.

The basis of the used roll charging is 80 wt.% Sulphate pulp from birch / pine (60/40) and 20 wt.% CaCO ₃ , purified to 200 CSF and containing 0.3 g / l of raw material, providing a conductivity of 555 μS / cm and a pH of 8.22.

Claims (33)

1. A method of manufacturing sizing paper, comprising adding to an aqueous suspension containing cellulosic fibers and optional fillers, (i) an anionic or cationic sizing dispersion; and (ii) a sizing promoter containing a cationic, organic polymer comprising one or more aromatic groups and an anionic polymer comprising one or more aromatic groups, wherein the anionic polymer is a step polymer, polysaccharide or natural aromatic polymer, molding and drying the resulting a suspension in which the dressing dispersion and the dressing promoter are added to the aqueous suspension separately. 2. The method according to claim 1, wherein the cationic organic polymer and the anionic polymer contained in the sizing promoter are added separately to the aqueous suspension. 3. The method according to claim 1, in which the anionic polymer comprising an aromatic group contained in the sizing promoter is added to the aqueous suspension after adding both the sizing dispersion and the cationic organic polymer comprising the aromatic group contained in the sizing promoter. 4. The method according to any one of the preceding paragraphs, in which the cationic, organic polymer is a cationic polysaccharide or a cationic vinyl additive polymer. 5. The method according to any one of the preceding paragraphs, in which the cationic, organic polymer is a cationic polysaccharide having the structural formula (I)

in which P represents a polysaccharide residue; A represents a chain of atoms, including atoms C and H, attaching N to the remainder of the polysaccharide; each of R ₁ and R ₂ represents H or a hydrocarbon group; R ₃ represents an aromatic hydrocarbon group; n is an integer from 2 to 300,000; X ^- represents an anionic counterion; and / or vinyl additive polymers obtained by polymerization of a cationic monomer or a mixture of monomers containing a cationic monomer represented by the general formula (II)

in which R ₁ represents H or CH ₃ ; each of R ₂ and R ₃ represents an alkyl group having from 1 to 3 carbon atoms; A ₁ represents O or NH; B ₁ represents an alkylene group having from 2 to 8 carbon atoms, or a hydroxypropylene group; Q represents a substituent comprising an aromatic group; X ^- represents an anionic counterion. 6. The method according to claim 1, in which the cationic, organic polymer is selected from cationic polysaccharides. 7. The method according to claim 1, wherein the cationic, organic polymer is selected from cationic starch. 8. The method according to claim 1, in which the cationic, organic polymer is selected from cationic polysaccharides having the structural formula (I)

in which P represents a polysaccharide residue; A represents a chain of atoms, including atoms C and H, attaching N to the remainder of the polysaccharide; each of R ₁ and R ₂ represents H or a hydrocarbon group; R ₃ represents an aromatic hydrocarbon group; n is an integer from 2 to 300,000; X ^- represents an anionic counterion. 9. The method of claim 8, in which A represents an alkylene group having from 2 to 18 carbon atoms, optionally interrupted or substituted by one or more heteroatoms; each of R ₁ and R ₂ represents H or an alkyl group having from 1 to 3 carbon atoms; R ₃ represents a benzyl or phenylethyl group. 10. The method according to any one of the preceding paragraphs, in which the anionic polymer is a step polymer or a natural aromatic polymer. 11. The method according to any one of claims 1 to 9, in which the anionic polymer is a polymer obtained by condensation of naphthalenesulfonate, or a modified lignin polymer. 12. The method according to any one of claims 1 to 9, in which the anionic polymer is a condensed naphthalenesulfonate or ligninsulfonate. 13. A method of manufacturing sizing paper, comprising adding to an aqueous suspension containing cellulosic fibers and optional excipients, (i) an anionic or cationic sizing dispersion containing a sizing agent and an anionic polymer comprising one or more aromatic groups; and (ii) a sizing promoter containing a cationic, organic polymer comprising one or more aromatic groups and an anionic polymer comprising one or more aromatic groups, molding and drying the resulting suspension, in which the sizing dispersion and sizing promoter are added separately. 14. The method according to item 13, in which the dressing dispersion further comprises a cationic, organic polymer comprising one or more aromatic groups. 15. The method according to item 13 or 14, in which the cationic, organic polymer is a cationic polysaccharide or cationic vinyl additive polymers. 16. The method according to item 13 or 14, in which the cationic, organic polymer is a cationic polysaccharide having the structural formula (I)

in which P represents a polysaccharide residue; A represents a chain of atoms, including atoms C and H, attaching N to the remainder of the polysaccharide; each of R ₁ and R ₂ represents H or a hydrocarbon group; R ₃ represents an aromatic hydrocarbon group; n is an integer from 2 to 300,000; X ^- represents an anionic counterion; or a vinyl additive polymer obtained by polymerizing a cationic monomer or a mixture of monomers containing a cationic monomer represented by the general formula (II)

in which R ₁ represents H or CH ₃ ; each of R ₂ and R ₃ represents an alkyl group having from 1 to 3 carbon atoms; A ₁ represents O or NH; B ₁ represents an alkylene group having from 2 to 8 carbon atoms, or a hydroxypropylene group; Q represents a substituent comprising an aromatic group; X ^- represents an anionic counterion. 17. The method according to claims 13 or 14, wherein the cationic, organic polymer is a cationic polysaccharide. 18. The method according to 17, in which the cationic, organic polymer is a cationic polysaccharide having the structural formula (I)

in which P represents a polysaccharide residue; A represents a chain of atoms, including atoms C and H, attaching N to the remainder of the polysaccharide; each of R ₁ and R ₂ represents H or a hydrocarbon group; R ₃ represents an aromatic, hydrocarbon group; n is an integer from 2 to 300,000; X ^- represents an anionic counterion. 19. The method according to p. 18, in which a represents an alkylene group having from 2 to 18 carbon atoms, optionally interrupted or substituted by one or more heteroatoms; each of R ₁ and r ₂ represents H or an alkyl group having from 1 to 3 carbon atoms; R ₃ represents a benzyl or phenylethyl group. 20. The method according to any one of claims 13-19, wherein the anionic polymer is a step polymer, a polysaccharide, or a natural aromatic polymer. 21. The method according to any one of claims 13-19, wherein the anionic polymer is a step polymer or a natural aromatic polymer. 22. The method according to any one of claims 13-19, wherein the anionic polymer is a polymer obtained by condensation of naphthalenesulfonate, or a modified lignin polymer. 23. The method according to any one of claims 13-19, wherein the anionic polymer is a condensed naphthalene sulfonate or ligninsulfonate. 24. The method according to any one of the preceding paragraphs, in which the sizing agent is a cellulose-reactive sizing agent. 25. The method according to any one of the preceding paragraphs, in which the sizing agent is a ketene dimer or acid anhydride. 26. The method according to any one of claims 1 to 24, in which the sizing agent is an acid anhydride. 27. The method according to any one of the preceding paragraphs, in which the conductivity of the suspension is at least 4.5 ms / cm. 28. The method according to any one of paragraphs.13-27, in which the cationic, organic polymer and anionic polymer contained in the dressing promoter are added to the aqueous suspension separately. 29. The method according to any one of claims 13 to 28, wherein the anionic polymer contained in the sizing promoter is added to the aqueous suspension after adding both the sizing dispersion and the cationic organic polymer contained in the sizing promoter. 30. The method according to any one of the preceding paragraphs, in which the amount of cationic, organic polymer sizing promoter added to the suspension is from about 0.001 to about 3 wt.% Based on dry fiber, and the amount of anionic polymer sizing promoter added to the suspension, is from about 0.001 to about 3 wt.% based on dry fiber. 31. The method according to any one of the preceding paragraphs, in which the amount added to the suspension of the dressing dispersion is from about 0.01 to about 5 wt.%, Calculated as the weight of the sizing agent on the weight of dry fibers. Priority on points: 08/07/2000 according to claims 13, 23-28, 30-31; 08/02/2001 according to claims 1-12, 14-22, 29.