EP2443282A1

EP2443282A1 - Method for reducing deposits in the drying section in the manufacture of paper, paperboard, and cardboard

Info

Publication number: EP2443282A1
Application number: EP10725129A
Authority: EP
Inventors: Christian Jehn-Rendu; Geert Andre Leon Vanhyfte
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-06-16
Filing date: 2010-06-11
Publication date: 2012-04-25
Also published as: US20120073774A1; WO2010145990A1; CN102803605A

Abstract

The invention relates to a method for reducing deposits in the drying section in the production of paper, paperboard, and cardboard by adding (a) at least one water-soluble cationic polymer and (b) at least one aqueous dispersion of a polymer sizing agent to a paper material, dehydrating the paper material to form sheets, and drying the paper products.

Description

Process for reducing deposits in the dryer section in the manufacture of paper, board and cardboard

description

The invention relates to a method for reducing deposits in the dryer section in the production of paper, paperboard and cardboard by adding (a) at least one water-soluble cationic polymer and (b) at least one aqueous dispersion of a polymer sizing agent to a paper stock, draining the paper stock under sheet formation and drying of the paper products.

In papermaking, deposits are usually caused by contaminants, which occur in particular in the recycling of waste paper. Such deposits are also referred to as stickies. These stickies come, for example, from adhesives, the line of paper or cardboard and resins that were not removed during fiber production. These stickies cause a strong reduction in the runnability of the paper machine, caused on the one hand by a significant increase in the cationic demand in the paper process and on the other hand by deposits in the dryer section. Increasing cationic demand reduces the efficiency of paper process chemicals, such as retention aids, while the deposits in the dryer section lead to breaks in the papermaking process.

Some papermaking processes are already known in the literature dealing with the problem of contaminant deposits.

From US Pat. No. 3,081,219 a process for the production of paper based on sulfite wood is known in which the addition of a sesquestating agent such as polyphosphates or a dispersant such as formaldehyde sulfonic acid or naphthalenesulfonic acid-formaldehyde condensate is intended to control the deposition of impurities ,

In US 4,871,865 a process for the production of paper is described in which a water-soluble polymer with methyl ether groups such as methyl cellulose is added to obtain control of the deposition of stickies.

Control of contaminant deposits in papermaking is also disclosed in US 4,871,424. Therein, the dosage of water-soluble, hydroxyl-bearing polymers such as polyvinyl alcohol is recommended.

From DE 42 40 110 A1 a process for the production of paper is known in which by the addition of water-soluble polyethyleneimines a control of Störstoffablagerungen is tried. US 6,387,215 teaches the use of water-soluble copolymers of acrylamide and vinyl acetates to control impurity deposits.

In particular, since tears in the dryer section, which are caused by deposits, repeatedly lead to disruptions in the ongoing papermaking process, there is a continuing need for the reduction of deposits, especially in the dryer section in the production of paper, cardboard and cardboard.

It is an object of the present invention to provide a method for reducing deposits in the dryer section in the production of paper, paperboard and cardboard, in which the running papermaking process is less affected by breaks. This method should be particularly suitable for newsprint and paperboard made from waste paper (containing deinked waste paper).

The object is achieved by a method for reducing deposits in the dryer section in the production of paper, paperboard and cardboard by adding (a) at least one water-soluble cationic polymer and (b) at least one aqueous dispersion of a polymer sizing agent to a paper stock, dewatering of the stock under sheet formation and drying of the paper products.

The said components (a) and (b) can be added to the stock in any order or even as a mixture.

The cationic polymers (a) are water-soluble. The solubility in water below

Normal conditions (20 ^° C., 1013 mbar) and pH 7 are, for example, at least 5% by weight, preferably at least 10% by weight.

The charge density of the cationic polymers (without counterion) is for example at least 0.5 meq / g and is usually in the range from 1 to 22 meq / g.

Water-soluble cationic polymers (a) for the purposes of the invention are polymers which may contain cationic, neutral or anionic structural units but in which the cationic structural units have an excess of at least 5 mol%, preferably of at least 10, over the anionic structural units Mole%, and more preferably at least 20 mole%.

The molecular weights M _{w of} the cationic polymers are, for example, at least 1 000 daltons. For example, they are mostly in the range of 5,000 to 5,000 daltons. Suitable water-soluble cationic polymers (a) are all amino- or ammonium-carrying compounds. The amino groups may be primary, secondary, tertiary or quaternary groups. For the polymers, polymers, polyaddition compounds or polycondensates are essentially polymers, wherein the polymers may have a linear or branched structure up to hyperbranched or dendritic structures. Furthermore, graft polymers are also applicable.

The water-soluble cationic polymer (a) is usually selected from the group of polymers comprising vinylamine units, cationic homo- and copolymers of (meth) acrylamide, polyallylamines, polyaminoalkylvinyl ethers, epihalohydrin reacted polyamidoamine compounds and polyamine compounds, amphoteric polymers having a total cationic charge, polymers containing ethyleneimine units and homopolymers with cationic or protonatable groups.

Such water-soluble cationic polymers (a) are, for example, polymers containing vinylamine units, cf. DE 35 06 832 A1 and DE 10 2004 056 551 A1. In the process according to the invention, polymers containing vinylamine units are reaction products which are obtainable

by polymerizing at least one monomer of the formula

in which R ¹ , R ² = H or C ₁ - to C ₆ -alkyl,

and subsequent partial or complete cleavage of the groups -CO-R ¹ from the polymerized in the polymer units of the monomers (I) to form amino groups

and or

by Hofmann degradation of polymers comprising acrylamide and / or methacrylamide units.

For example, in one embodiment of the invention, polymers containing vinylamine units include the reaction products obtainable by polymerizing (1.) at least one monomer of the formula

in which R ¹ , R ² = H or C ₁ - to C ₆ -alkyl,

(2.) optionally at least one other monoethylenically unsaturated monomer and

(3.) optionally at least one crosslinking monomer having at least two double bonds in the molecule

and subsequent partial or complete cleavage of the groups -CO-R ¹ from the polymerized in the polymer units of the monomers (I) to form amino groups.

Preferably, polymers containing vinylamine units are the reaction products obtainable by polymerizing N-vinylformamide and then eliminating formyl groups from the vinylformamide units polymerized into the polymer to form amino groups, or using the reaction products obtained by copolymerizing

(1.) N-vinylformamide and (2.) acrylonitrile

and subsequent cleavage of formyl groups from the copolymerized in the copolymer vinylformamide units to form amino groups are available.

In another embodiment of the invention, the polymers containing vinylamine units may also be amphoteric if they have a total cationic charge. The content of cationic groups in the polymer should be at least 5 mol%, preferably at least 10 mol%, above the content of anionic groups. Such polymers are obtainable, for example, by polymerizing (1.) at least one monomer of the formula

in which R ¹ , R ² = H or C ₁ - to C ₆ -alkyl,

(2.1) at least one acid-functional monomer selected from monoethylenically unsaturated sulfonic acids, monoethylenically unsaturated phosphonic acids and monoethylenically unsaturated carboxylic acids having 3 to

8 C atoms in the molecule and / or their alkali metal, alkaline earth metal or ammonium salts,

(2.2) optionally at least one other neutral and / or cationic monomer and

and subsequent partial or complete cleavage of the groups -CO-R ¹ from the polymerized in the polymer units of the monomers (I) to form amino groups, wherein the content of amino groups in the copolymer at least 5 mol% above the content of copolymerized acid groups of the monomers (2.1) is.

Also of interest are polymers containing amphoteric vinylamine units which carry a total cationic charge and which are obtained, for example, by copolymerizing

(1.) N-vinylformamide,

(2.1) acrylic acid, methacrylic acid and / or their alkali metal, alkaline earth metal or ammonium salts and

(2.2) optionally acrylonitrile and / or methacrylonitrile

and subsequent partial or complete cleavage of formyl groups from the copolymerized in the polymer N-vinylformamide to form amino groups are obtainable, wherein the content of amino groups in the copolymer is at least 5 mol% above the content of copolymerized acid groups of the monomers (2.1). Examples of monomers of the formula (I) are N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-ethylacetamide, N-vinylpropionamide and N-vinyl-N methylpropionamide and N-vinylbutyramide. The monomers of group (a) may be used alone or in admixture in the copolymerization with the monomers of the other groups. Preferably used monomer of this group is N-vinylformamide.

These polymers may optionally be modified by copolymerizing the N-vinylcarboxamides (1.) together with (2.) at least one other monoethylenically unsaturated monomer and then hydrolyzing the copolymers to form amino groups. If anionic monomers are used in the copolymerization, the hydrolysis of the copolymerized vinylcarboxamide units is conducted so far that the molar excess of amine units compared to the anionic units in the polymer is at least 5 mol%.

Examples of monomers of group (2) are esters of α, ß-ethylenically unsaturated mono- and dicarboxylic acids with Ci-C3o-alkanols, C2-C3o-alkanediols and C2-C30-amino alcohols, amides of α, ß-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N, N-dialkyl derivatives, nitriles of α, ß-ethylenically unsaturated mono- and dicarboxylic acids, esters of vinyl alcohol and allyl alcohol with C1-C30 monocarboxylic acids, N-vinyl lactams, nitrogen-containing heterocycles with α, ß-ethylenic unsaturated double bonds, vinyl aromatics, vinyl halides, vinylidene halides, C 2 -C 8 monoolefins, and mixtures thereof.

Suitable representatives are e.g. Methyl (meth) acrylate (in which (meth) acrylate in the sense of the present invention means both acrylate and methacrylate), methyl acrylate, ethyl (meth) acrylate, ethyl ethacrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, tert-butyl methacrylate, n-ocytl (meth) acrylate, 1,1,3,3-tetramethylbutyl (meth) acrylate, ethylhexyl (meth) acrylate and mixtures thereof.

Suitable additional monomers of group (2) are furthermore the esters of α, β-ethylenically unsaturated mono- and dicarboxylic acids with aminoalcohols, preferably C 2 -C 12 -aminoalcohols. These may be d-Cs-monoalkylated or -dialkylated on the amine nitrogen. Suitable acid components of these esters are, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, crotonic acid, maleic anhydride, monobutyl maleate and mixtures thereof. Preference is given to using acrylic acid, methacrylic acid and mixtures thereof. These include, for example, N-methylaminomethyl (meth) acrylate, N-methylaminoethyl (meth) acrylate, N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N , N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate and N, N-dimethylaminocyclohexyl (meth) acrylate. Further suitable monomers of group (2) are 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and mixtures thereof.

Further suitable monomers of group (2) are acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-butyl (meth) acrylamide, N - (tert-butyl) (meth) acrylamide, N-octyl (meth) acrylamide, N- (1,1,3,3-tetramethylbutyl) (meth) acrylamide, N- (ethylhexyl) (meth) acrylamide and mixtures thereof ,

In addition, as further monomers of the group (2.) N- [2- (dimethylamino) ethyl] acrylamide, N- [2- (dimethylamino) ethyl] methacrylamide, N- [3- (dimethylamino) propyl] acrylamide, N- [3- (dimethylamino) propyl] methacrylamide, N- [4- (dimethylamino) butyl] acrylamide, N- [4- (dimethylamino) butyl] methacrylamide, N- [2- (diethylamino) ethyl] acrylamide, N- [2 - (Diethylamino) ethyl] methacrylamide and mixtures thereof.

Further examples of monomers of group (2) are nitriles of α, β-ethylenically unsaturated mono- and dicarboxylic acids such as, for example, acrylonitrile and methacrylonitrile. The presence of units of these monomers in the copolymer leads during or after the hydrolysis to products which have amidine units, cf. e.g. EP 0 528 409 A1 or DE 43 28 975 A1. Namely, in the hydrolysis of N-vinylcarboxylic acid amide units, in a secondary reaction, aminin units are formed by reacting vinylamine units with an adjacent vinylformamide unit or, if a nitrile group is present as an adjacent group in the polymer. In the following, the indication of vinylamine units in the amphoteric copolymers or in unmodified homo- or copolymers always means the sum of vinylamine and amidine units.

Suitable monomers of group (2) are furthermore N-vinyllactams and their derivatives, which are e.g. may have one or more d-Cβ-alkyl substituents (as defined above). These include N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-ethyl-2-pyrrolidone, N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam and mixtures thereof.

Further suitable monomers of group (2) are N-vinylimidazoles and alkylvinylimidazoles, in particular methylvinylimidazoles such as, for example, 1-vinyl-2-methylimidazole, 3-vinylimidazole N-oxide, 2- and 4-vinylpyridine N-oxides and betainic acid. derivatives and quaternization products of these monomers, as well as ethylene, propylene len, isobutylene, butadiene, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and mixtures thereof.

The abovementioned monomers can be used individually or in the form of any mixtures. Typically, they are available in quantities of 1 to

90 mol%, preferably 10 to 80 mol% and particularly preferably 10 to 60 mol% used.

For the preparation of amphoteric Copoylmerisaten come as other monoethylenically unsaturated monomers of group (2.) and anionic monomers into consideration, which are referred to above as monomers (2.1). If appropriate, they may be copolymerized with the above-described neutral and / or cationic monomers (2.2). However, the amounts of anionic monomers (2.1) is at most 45 mol%, so that the resulting amphoteric copolymer has a total cationic charge see.

Examples of anionic monomers of group (2.1) are ethylenically unsaturated C3- to C6-carboxylic acids such as acrylic acid, methacrylic acid, dimethacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, methylenemalonic acid, allylacetic acid, vinylacetic acid and crotonic acid. Also suitable as monomers of this group are monomers containing sulfonic groups, such as vinylsulfonic acid, acrylamido-2-methylpropanesulfonic acid and styrenesulfonic acid, and monomers containing phosphonic groups, such as vinylphosphonic acid. The monomers of this group can be used alone or in admixture with each other, in partially or completely neutralized form in the copolymerization. For neutralization, for example, alkali metal or alkaline earth metal bases, ammonia, amines and / or alkanolamines are used. Examples of these are sodium hydroxide solution, potassium hydroxide solution, soda, potash, sodium bicarbonate, magnesium oxide, calcium hydroxide, calcium oxide, triethanolamine, ethanolamine, morpholine, diethylenetriamine or tetraethylene pentamine.

A further modification of the copolymers is possible by using in the copolymerization monomers of group (3.) which contain at least two double bonds in the molecule, for example triallylamine, methylenebisacrylamide, glycol diacrylate, glycol dimethacrylate, glycerol triacrylate, pentaerythritol triallyl ether, at least twice with acrylic acid and / or methacrylic acid esterified polyalkylene glycols or polyols such as pentaerythritol, sorbitol or glucose. These are so-called crosslinkers. If at least one monomer of the above group is used in the polymerization, the amounts used are up to 2 mol%, for example 0.001 to 1 mol%. Furthermore, to modify the polymers, it may be useful to combine the use of the above crosslinked with the addition of regulators. Typically, from 0.001 to 5 mole percent is used. All regulators known in the literature can be used, for example sulfur compounds such as mercaptoethanol, 2-ethylhexyl thioglycolate, thioglycolic acid and dodecylmercaptan, and also sodium hypophosphite, formic acid or tribromochloromethane and terpinolene.

The polymers containing vinylamine units also include hydrolyzed graft polymers of, for example, N-vinylformamide on polyalkylene glycols, polyvinyl acetate, polyvinyl alcohol, polyvinylformamides, polysaccharides such as starch, oligosaccharides or monosaccharides. The graft polymers can be obtained by free-radically polymerizing, for example, N-vinylformamide in aqueous medium in the presence of at least one of the stated grafting bases together with copolymerizable other monomers and then hydrolyzing the grafted vinylformamide units in a known manner to give vinylamine units.

The hydrolysis of the copolymers described above can be carried out in the presence of acids or bases or else enzymatically. In the case of hydrolysis with acids, the vinylamine groups formed from the vinylcarboxamide units are present in salt form. The hydrolysis of vinylcarboxamide copolymers is described in detail in EP 0 438 744 A1, page 8, line 20 to page 10, line 3. The explanations made there apply correspondingly to the preparation of the cationic and / or amphoteric polymers containing vinylamine units to be used according to the invention and having a total cationic charge.

As described above, polymers containing vinylamine units also include the reaction products obtained by Hofmann degradation of homo- or copolymers of acrylamide or methacrylamide in aqueous medium in the presence of caustic soda and sodium hypochlorite and subsequent decarboxylation of the carbamate groups of the reaction products in the presence of an acid are available. Such polymers are known, for example, from EP 0 377 313 and WO 2006/0751 15 A1. The preparation of polymers containing vinylamine groups is discussed in detail in WO 2006/0751 15 A1, page 4, line 25 to page 10, line 22 and in the examples on pages 13 and 14, for example. The information given there applies to the characterization of the polymers containing vinylamine units prepared by Hofmann degradation.

It is based on polymers containing acrylamide and / or methacrylamide units. These are homopolymers or copolymers of acrylamide and methacrylamide. Examples of suitable comonomers are dialkylaminoalkyl (meth) acrylamides, diallylamine, methyldiallylamine and the salts of amines and the quaternized amines into consideration. Also suitable as comonomers are dimethyldiallylammonium salts, acrylamidopropyltrimethylammonium chloride and / or methacrylamidopropyltrimethylammonium chloride, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, vinyl acetate and acrylic and methacrylic acid esters. Suitable comonomers are, if appropriate, also anionic monomers such as acrylic acid, methacrylic acid, maleic anhydride, maleic acid, itaconic acid, acrylamidomethylpropanesulfonic acid, methallylsulfonic acid and vinylsulfonic acid and the alkali metal, alkaline earth metal and ammonium salts of said acidic monomers, not more than 5 mol% of these monomers being included the polymerization can be used. The amount of water-insoluble monomers is chosen in the polymerization so that the resulting polymers are soluble in water.

If appropriate, comonomers may also be used crosslinkers, e.g. ethylenically unsaturated monomers which contain at least two double bonds in the molecule, such as triallylamine, methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, triallylamine and trimethylol trimethacrylate. If a crosslinker is used, the amounts used are, for example, 5 to 5000 ppm. The polymerization of the monomers can be carried out by any known method, e.g. by free-radical initiated solution, precipitation or suspension polymerization. If appropriate, it is possible to work in the presence of customary polymerization regulators.

When Hofmann degradation is for example from 20 to 40 wt .-% aqueous solutions of at least one acrylamide and / or methacrylamide units containing polymers. The ratio of alkali metal hypochlorite to (meth) acrylamide units in the polymer is decisive for the resulting content of amine groups in the polymer. The molar ratio of alkali metal hydroxide to alkali metal hypochlorite is for example 2 to 6, preferably 2 to 5. For a certain amine group content in the degraded polymer is calculated for the degradation of the polymer required amount of alkali metal hydroxide.

The Hofmann degradation of the polymer takes place for example in the temperature range from 0 to 45 ⁰ C, preferably 10 to prevent the starting polymer to 20 ⁰ C in the presence of quaternary ammonium salts as a stabilizer to amide groups, a side reaction of the resulting amino groups with the A-. After completion of the reaction with alkali metal hydroxide / alkali metal hypochlorite, the aqueous reaction solution is passed into a reactor in which an acid is introduced for the decarboxylation of the reaction product. The pH of the reaction product containing vinylamine units is adjusted to a value of 2 to 7. The concentration of the degradation product containing vinylamine units is, for example, more than 3.5% by weight, in most cases above 4.5% by weight. The aqueous polymer solutions can be concentrated for example by means of ultrafiltration. Further suitable water-soluble cationic polymers (a) are cationic homo- and copolymers of (meth) acrylamide and can be prepared by polymerization of the monomers of group (2) described above, whereby the quaternization products of these monomers with C 1 -C 5 -alkyl chloride, d-Cs dialkyl sulfate, C1-C16 epoxides or benzyl chloride are suitable.

Allylamine, dialkyldiallylammonium chlorides, in particular dimethyldiallylammonium chloride and diethyldiallylammonium chloride, and the monomers of the formula (II) known from WO 01/36500 A1 are suitable for the preparation of polyallylamines as water-soluble cationic polymers (a).

R O

H ₂ C 1 CCO [Al-] _m H • n HY (II),

wherein

R is hydrogen or C 1 to C ₄ -alkyl,

- [Al-] _{m is} a linear or branched oligoalkyleneimine chain having m alkyleneimine units, m is an integer in the range of 1 to 20, and the number average m in the oligoalkyleneimine chains is at least 1.5, Y is the anion equivalent of a mineral acid, and n is a number of 1 <n <m.

Monomers or monomer mixtures in which in the above formula (II) the number average of m is at least 2.1, usually 2.1 to 8, are preferred. They are obtainable by reacting an ethylenically unsaturated carboxylic acid with an oligoalkyleneimine, preferably in the form of an oligomer mixture. The resulting product may optionally be converted with a mineral acid HY in the acid addition salt. Such monomers can be polymerized in an aqueous medium in the presence of an initiator which initiates a free radical polymerization to cationic homo- and copolymers.

Further suitable water-soluble cationic polymers (a) are polyaminoalkyl vinyl ethers. For this purpose, suitable monomers are known from the earlier EP application with the file reference 07 117 909.7. These are alkyleneimine units containing aminoalkyl vinyl ethers of the formula H ₂ C = CH OX NH [Al-] _n H

wherein

[Al-] n is a linear or branched oligoalkyleneimine chain with n Alkylenimineinhei- th, n is a number of at least 1 and

X represents a straight-chain or branched C 2 - to C 6 -alkylene group and

Salts of the monomers (III) with mineral acids or organic acids and quaternization products of the monomers (III) with alkyl halides or dialkyl sulfates. These compounds are accessible by addition of alkyleneimines to amino-C2- to ce- alkylvinylether.

The abovementioned monomers can form water-soluble cationic homopolymers (a) alone or together with at least one other neutral monomer to form water-soluble cationic copolymers or with at least one acid group-containing monomer to give amphoteric copolymers which, given a molar excess of copolymerized cationic monomers, have a total cationic charge carry, be polymerized.

Suitable neutral monomers which are copolymerized with the abovementioned cationic monomers for the preparation of cationic polymers are, for example, esters of α, β-ethylenically unsaturated mono- and dicarboxylic acids with C 1 -C 30 -alkanols, C 2 -C 3 -alkanediols, amides α , .beta.-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N, N-dialkyl derivatives, esters of vinyl alcohol and allyl alcohol with saturated C.sub.1-C.sub.3-monocarboxylic acids, vinylaromatics, vinyl halides, vinylidene halides, C.sub.2-C.sub.-monoolefins and Mixtures thereof.

Other suitable comonomers are e.g. Methyl (meth) acrylate, methyl ethacrylate, ethyl (meth) acrylate, ethyl ethacrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, tert-butyl ethacrylate, n-octyl (meth ) acrylate, 1,1,3,3-tetramethylbutyl (meth) acrylate, ethylhexyl (meth) acrylate and mixtures thereof.

Also suitable are acrylamide, substituted acrylamides, methacrylamide, substituted methacrylamides such as, for example, acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N- (n-butyl) ( meth) acrylamide, tert-butyl (meth) acrylamide, n-octyl (meth) acrylamide, 1, 1, 3,3-tetramethylbutyl (meth) acrylamide and ethylhexyl (meth) acrylamide and acrylonitrile and methacrylonitrile and mixtures of the monomers mentioned. Further monomers for modifying the cationic polymers are 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, etc., and mixtures thereof.

Other suitable monomers for the copolymerization with the above-mentioned cationic monomers are N-vinyl lactams and their derivatives, e.g. one or more Ci-Cβ-alkyl substituents, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, etc. may have. These include e.g. N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-ethyl-2-pyrrolidone, N-vinyl-6-methyl-2-piperidone, N- Vinyl 6-ethyl-2-piperidone, N-vinyl-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam, etc.

Suitable comonomers for the copolymerization with the abovementioned cationic monomers are also ethylene, propylene, isobutylene, butadiene, styrene, α-

Methylstyrene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and mixtures thereof.

In addition, also suitable with epihalohydrin reacted Polyamidoaminverbin- fertilize and polyamine compounds as they are known from DE 24 34 816 A1 and US 3,258,393.

The German Offenlegungsschrift describes nitrogen-containing condensation products which are obtained by reacting polyamidoamine compounds with polyalkylene oxide derivatives reacted at the terminal hydroxyl groups with epichlorohydrin. For the preparation of such condensation products, reference is explicitly and fully made to the disclosure of DE 24 34 816 A1, in particular to the passage of page 4, paragraph 3 to page 6 inclusive.

Epihalohydrin reacted polyamine compounds are known for example from US 3,258,393. Thus, epichlorohydrin is reacted with a bifunctional and a polyfunctional amine. Suitable bifunctional amines are methylamine, ethylamine, ethanolamine, dimethylamine, N, N'-dimethylethylenediamine, aniline, piperazine and ethylaminoacetate. Examples of polyfunctional amines are ethylenediamine, N-methylethylenediamine, ammonia, hydrazine, p-phenylenediamine and others in

US 3,258,393 amines, in particular the disclosed in column 4 polyfunctional amines. The bifunctional and polyfunctional amines are usually used in equimolar ratio. In addition to epichlorohydrin, other crosslinkers, such as glyoxal, 1,2-dichloroethane, diglycidyl ether, methylenebisacrylamide and 1,4-dichlorobutene and also other crosslinkers mentioned in column 4 of US Pat. No. 3,258,393, are suitable according to this US Pat. For the preparation of such condensation products, reference is expressly and fully made to the disclosure of US 3,258,393. Of course, the epihalohydrin reacted polyamine compounds can be prepared based on only a bifunctional amine or a polyfunctional amine.

As described above, cationic polymers also mean amphoteric polymers which carry a total cationic charge. In the case of the amphoteric polymers, the content of cationic groups is, for example, at least 5 mol% higher than the content of anionic groups in the polymer. Such polymers are z. B. accessible by adding a cationic monomer such as N, N-

Dimethylaminoethylacrylamide in the form of the free base, copolymerized in partially neutralized with an acid or in quaternized form with at least one acid group-containing monomer, wherein the cationic monomer is used in a molar excess, so that the resulting polymers carry a total cationic charge.

Furthermore, polymers containing ethyleneimine units are suitable as water-soluble cationic polymers for the process according to the invention. These include all polymers which are obtainable by polymerization of ethyleneimine in the presence of acids, Lewis acids or haloalkanes such as homopolymers of ethyleneimine or

Graft polymers of ethyleneimine, cf. US 2,182,306 or US 3,203,910. If desired, these polymers can subsequently be subjected to crosslinking. As crosslinkers come e.g. all multifunctional compounds containing groups reactive with primary amino groups, e.g. multifunctional epoxides such as bisglycidyl ethers of oligo- or polyethylene oxides or other multifunctional alcohols such as glycerol or sugars, mulifunctional carboxylic acid esters, multifunctional isocyanates, polyfunctional acrylic or methacrylic acid esters, multifunctional acrylic or methacrylic acid amides, epichlorohydrin, multifunctional acid halides, multifunctional nitriles, α, ω-chlorohydrin ethers of Oligo- or polyethylene oxides or other multifunctional alcohols such as glycerol or sugars, divinylsulfone, maleic anhydride or ω-Halogencarbonsäurechloride, multifunctional haloalkanes in particular α, ω-dichloroalkanes. Further crosslinkers are described in WO 97/25367 A1, pages 8 to 16.

Polymers containing ethyleneimine units are known, for example, from EP 0 41 1 400 A1, DE 24 34 816 A1 and US Pat. No. 4,066,494.

For example, in the process according to the invention, at least one water-soluble cationic polymer from the group of polymers containing ethyleneimine units is used Homopolymers of ethyleneimine, polyethylenimines reacted with at least bifunctional crosslinkers, polyamidoamines grafted with ethyleneimine and reacted with at least bifunctional crosslinkers,

Reaction products of polyethylenimines with monobasic carboxylic acids to amidated polyethylenimines,

Michael addition products of polyethyleneimines to ethylenically unsaturated acids, salts, esters, amides or nitriles of monoethylenically unsubstituted carboxylic acids, phosphonomethylated polyethyleneimines, carboxylated polyethyleneimines and alkoxylated polyethyleneimines.

Polymers which are obtained by first condensing at least one polycarboxylic acid with at least one polyamine to form polyamidoamines, then grafting with ethyleneimine and subsequently crosslinking the reaction products with one of the abovementioned compounds belong to the ethylenimine units which are preferably suitable Links. A method for producing such compounds is described, for example, in DE 24 34 816 A1, where α, ω-

Chlorohydrin ethers of oligo- or polyethylene oxides are used as crosslinkers application.

Particularly preferred are products of the two above types which have been subjected to ultrafiltration and thus optimized in their molecular weight distribution. Such ultrafiltered products are described in detail in WO 00/67884 A1 and WO 97/25367 A1. These publications and the disclosure contained therein are expressly incorporated herein by reference.

Reaction products of polyethyleneimines with monobasic carboxylic acids to amidated polyethyleneimines are known from WO 94/12560 A1. Michael addition products of polyethyleneimines to ethylenically unsaturated acids, salts, esters, amides or nitriles of monoethylenically unsaturated carboxylic acids are the subject of WO 94/14873 A1. Phosphonomethylated polyethyleneimines are described in detail in WO 97/25367 A1. Carboxylated polyethyleneimines are obtainable, for example, by means of a plug synthesis by reacting polyethyleneimines with formaldehyde and ammonia / hydrogen cyanide and hydrolysing the reaction products. Alkoxylated polyethyleneimines can be prepared by reacting polyethyl imines with alkylene oxides such as ethylene oxide and / or propylene oxide.

In addition, in the process according to the invention, homopolymers of cationic or basic (meth) acrylic acid esters, each having an amino group and / or quaternary ammonium group, or cationic or basic (Meth) acrylamides, each carrying an amino group and / or quaternary ammonium group, can be used.

Such compounds having an amino group are those of the general formula (IV):

in the

A = O, NH,

B = C _n H2n, where n = an integer in the range of 1 to 8,

R ¹ , R ² = C _m H2m + i, m = an integer in the range of 1 to 4 and

R ³ = H, CH ₃

mean.

The compounds having quaternary ammonium groups can be characterized by the following formula (V):

O

R '

H ₂ CH-HC - C - A - B - N - R ² X ^" (V)

R ⁴

^RJ

in the

X = OH, Cl, Br, CH ₃ -OSO ^{3 "} , R ₄ = C _m H2m + i, m = an integer in the range from 1 to 4, and the remaining substituents have the abovementioned meaning,

mean.

The compounds of the formula (V) are generally referred to as cationic monomers, those of the formula (IV) as basic monomers. Basic ethylenically unsaturated monomers are, for example, acrylic acid and methacrylic acid esters of amino alcohols, for example N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminopropyl acrylate, N, N Dimethylaminopropyl methacrylate, N, N- Dibutylaminopropyl acrylate, N, N-dibutylaminopropyl methacrylate, N, N-dimethylaminoneopentyl acrylate, amino group-containing derivatives of acrylamide or methacrylamide such as N, N-dimethylaminoethylacrylamide, N, N-dimethylaminoethylmethacrylamide, N, N-dimethylaminopropylacrylamide and N, N-dimethylaminopropylmethacrylamide

The quaternary compounds of formula (V) are obtained by reacting the basic monomers of formula (IV) with known quaternizing agents, e.g. with methyl chloride, benzyl chloride, ethyl chloride, butyl bromide, dimethyl sulfate and diethyl sulfate or epichlorohydrin. These monomers lose their basic character in the quaternary form. Examples which may be mentioned are: N, N, N-trimethylammoniumethyl acrylate chloride, N, N, N-trimethylammoniumethyl methacrylate chloride, N, N, N-trimethylammoniumethylmethacrylamide chloride, N, N, N-trimethylammoniumpropylacrylamide chloride, N, N, N Trimethylammoniumpropylmethacrylamide chloride, N, N, N-

Trimethylammoniumethylacrylamid chloride, and the corresponding methosulfates and sulfates.

The monomers of this group are preferably selected from N, N-dimethylaminopropylmethacrylamide, N, N-dimethylaminoethyl methacrylate and N, N-dimethylaminoethyl acrylate, in each case in the form of the salt with at least one mineral acid or carboxylic acid and / or in quaternary form. Preferred quaternizing agent is methyl chloride.

All of the aforementioned cationic homopolymers and copolymers can be prepared by solution, precipitation, suspension or emulsion polymerization. Preference is given to solution polymerization in aqueous media. Suitable aqueous media are water and mixtures of water and at least one water-miscible solvent, e.g. As an alcohol such as methanol, ethanol, n-propanol, etc.

The polymerization temperatures are preferably in a range of about 30 to 200 ⁰ C, more preferably 40 to 110 ⁰ C. The polymerization is usually carried out under atmospheric pressure, but it can also proceed under reduced or elevated pressure. A suitable pressure range is between 0.1 and 5 bar.

To prepare the polymers, the monomers can be polymerized by means of free-radical initiators.

As initiators for the radical polymerization, the peroxo and / or azo compounds customary for this purpose can be used, for example alkali metal or ammonium peroxydisulfates, diacetyl peroxide, dibenzoyl peroxide, succinyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, tert. Butyl perpivalate, tert-butyl peroxy-2 ethylhexanoate, tert-butyl permalate, cumene hydroperoxide, diisopropyl peroxydicarbamate, bis (o-toluoyl) peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, tert-butyl perisobutyrate, tert-butyl peracetate, di-tert-amyl peroxide, tert-butyl hydroperoxide , Azo-bis-isobutyronitrile, azo-bis (2-amidinopropane) dihydrochloride or 2,2'-azobis (2-methyl-butyronitrile). Also suitable are initiator mixtures or redox initiator systems, such as ascorbic acid / iron (II) sulfate / sodium peroxodisulfate, tert-butyl hydroperoxide / sodium disulfite, tert-butyl hydroperoxide / sodium hydroxymethanesulfinate, H 2 O 2 / CU-I or iron-II compounds ,

To adjust the molecular weight, the polymerization can be carried out in the presence of at least one regulator. As a regulator, the usual compounds known in the art, such. B. sulfur compounds, for. As mercaptoethanol, 2-ethylhexyl thioglycolate, thioglycolic acid, sodium hypophosphite, formic acid or dodecylmercaptan and Tribromchlormethan or other compounds which act regulating the molecular weight of the polymers obtained, are used.

All of the aforementioned cationic polymers can be modified by carrying out the polymerization of the cationic monomers and optionally of the mixtures of cationic monomers and the comonomers in the presence of at least one crosslinker. A crosslinker is understood as meaning those monomers which contain at least two double bonds in the molecule, eg. B. methylene bisacrylamide, glycol diacrylate, glycol dimethacrylate, glycerol triacrylate, Pentae- rythrittriallylether, at least twice with acrylic acid and / or methacrylic acid esterified polyalkylene glycols or polyols such as pentaerythritol, sorbitol or glucose. If at least one crosslinker is used in the copolymerization, the amounts used, for example, up to 2 mol%, z. B. 0.001 to 1 mol%.

Furthermore, the cationic polymers can be modified by the subsequent addition of crosslinkers, i. by the addition of compounds having at least two amino groups reactive groups, such as. B.

Di- and polyglycidyl compounds, di- and polyhalogen compounds, - compounds having two or more isocyanate groups, possibly blocked carbonic acid derivatives,

Compounds having two or more double bonds suitable for Michael addition, di- and polyaldehydes, monoethylenically unsaturated carboxylic acids, their esters and anhydrides. The at least one water-soluble cationic polymer (a) is used in the process according to the invention for reducing deposits in the dryer section in the production of paper, for example in an amount of 0.005 to 2.0% by weight, preferably 0.005 to 1% by weight, particularly preferably from 0.01 to 0.3% by weight, based in each case on the solids content of the paper stock.

Suitable aqueous dispersions of polymer sizes in the process according to the invention are in principle all polymer sizes known to the person skilled in the art, which are used both as surface size agents and as size sizes in papermaking.

Preferred are finely divided, cationic or amphoteric, aqueous polymer dispersions, which are frequently obtainable by a two-stage polymerization. In this case, a prepolymer is prepared as a dispersant or protective colloid in the first polymerization and then carried out in an aqueous solution of this prepolymer in the presence of ethylenically unsaturated monomers, an emulsion polymerization.

Such finely divided, cationic, aqueous polymer dispersions are known to the person skilled in the art and are i.a. in DE 24 25 585 A1, DE 24 54 397 A1, EP 0 051 144 A1, EP 0 058 313 A1, US Pat. No. 4,659,431, EP 1 180 527 A1, WO 05/121 195 A1, WO 08/071690 A1 and in the older one EP application with the file reference 09 161 929.6 discloses.

Usually, the prepolymer is obtainable by solution polymerization of

(i) nitrogen-containing monomers which carry an amino group and / or quaternary ammonium group,

(ii) nonionic, hydrophobic, ethylenically unsaturated monomers, (iii) optionally acid-group-containing ethylenically unsaturated monomers, and

(iv) optionally nonionic, hydrophilic, ethylenically unsaturated monomers.

The prepolymer obtained in this way is then subjected as a dispersant or protective colloid in the presence of ethylenically unsaturated monomers to an emulsion polymerization, wherein the ethylenically unsaturated monomers used are a monomer mixture of nonionic, hydrophobic, ethylenically unsaturated monomers.

As (i) nitrogen-containing monomers which carry an amino group and / or quaternary ammonium group, it is possible to use those compounds which have been previously disclosed with the my (IV) and (V) for the preparation of homopolymers of cationic or basic (meth) acrylic acid esters, each having an amino group and / or quaternary ammonium group, or cationic or basic (meth) acrylamides, each having an amino group and / or quaternary ammonium group be used as (a) water-soluble cationic polymers. The aforementioned preferred compounds and their quaternization products are also preferably used as (i) nitrogen-containing monomers.

The monomers of group (ii) for the preparation of the prepolymer are nonionic see, hydrophobic, ethylenically unsaturated compounds. These are those monomers which are not appreciably soluble in water and form hydrophobic polymers. Such monomers include, for example, vinyl aromatic monomers such as styrene and substituted styrenes, eg, α-methylstyrene and ethylstyrene; Carboxylic esters of ethylenically unsaturated C 3 -C 6 -mono- and dicarboxylic acid with monohydric C 1 -C 18 -alcohols, for example C 1 - to C 18- (meth) acrylates, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, sopropyl acrylate, isopropyl methacrylate, n-, iso- and tert-butyl acrylate, n-, iso- and tert-butyl methacrylate, hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, n-decyl acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate , Stearyl acrylate and stearyl methacrylate; Nitriles of C3 to C6 mono- and dicarboxylic acids such as acrylonitrile and methacrylonitrile; Vinyl esters of linear or branched d- to C3o-carboxylic acids such as vinyl laurate, - stearate, vinyl propionate, vinyl versatate, vinyl acetate, Propylheptansäureviny- lester, neodecanoate (VeoVA ^® 10 Hexion Specialty Chemicals), vinyl neononanoate (VeoVa ^® 9 Hexion Specialty Chemicals) as well

Vinylpelargonat; Alkenes having 2 to 10 carbon atoms, preferably having a terminal double bond, such as ethylene or diolefins, such as butadiene and isoprene.

Styrene, acrylates, methacrylates, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate and butadiene are preferably used from this monomer group. Specific preferred acrylic acid esters and methacrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, tertiary butyl acrylate, ethylhexyl acrylate, lauryl acrylate, and the corresponding esters of methacrylic acid.

It is of course possible, and also preferred, to use any mixtures of said monomers, e.g. Mixtures of styrene and (meth) acrylic acid esters such as n- and / or tert-butyl acrylate, styrene and ethylhexyl acrylate, styrene and acrylonitrile and (meth) acrylic acid esters such as n- and / or tert-butyl acrylate.

Suitable monomers of group (iii) are ethylenically unsaturated C3- to Cβ-

Carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, ethacrylic acid, crotonic acid, monoesters of ethylenically unsaturated dicarboxylic acids such as monomethyl maleate, monomethyl fumarate, monoethyl maleate, monoethyl fumarate, monopropyl maleate, monopropyl fumarate, mono-n-butyl maleate and mono-n-butyl fumarate, as well as styrenecarboxylic acids and ethylenically unsaturated anhydrides such as maleic anhydride and itaconic anhydride. Also suitable as monomers (iii) are monomers containing sulfonic acid and phosphonic acid groups, such as

Acrylamido-2-methylpropanesulfonic acid and vinylphosphonic acid. The acid group-containing monomers can be used in the form of the free acid groups and partially or completely neutralized with alkali metal bases, alkaline earth metal bases, ammonia and / or amines neutralized form. Acrylic acid and methacrylic acid or mixtures of acrylic acid and methacrylic acid in any ratio are preferably used from this monomer group.

Monomers (iv) optionally used to modify the properties of the prepolymer are nonionic, hydrophilic, ethylenically unsaturated monomers, e.g. Amides or substituted amides of ethylenically unsaturated mono- or dicarboxylic acids such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide and N-ethylmethacrylamide.

The prepolymer is usually prepared in the manner of a solution polymerization from the aforementioned monomers (i) to (iv). Subsequently, this prepolymer is diluted to a concentration of, for example, 2 to 25% by weight in water and then subjected to the second polymerization step.

In this second polymerization stage, the aforementioned monomers of group (ii) are subjected to emulsion polymerization in the presence of the prepolymer. Styrene, acrylic esters, methacrylic acid esters, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate and butadiene, as well as individual acrylic esters and methacrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, ethylhexyl acrylate, lauryl acrylate and the corresponding ones are preferred from this monomer group Esters of methacrylic acid. Particular preference is given to using any desired mixtures of the monomers mentioned, e.g. Mixtures of styrene and (meth) acrylic acid esters such as n- and / or tert-butyl acrylate, styrene and ethylhexyl acrylate, styrene and acrylonitrile and (meth) acrylic acid esters such as n- and / or tert-butyl acrylate.

Such monomer mixtures can also be polymerized in the presence of a mostly degraded starch.

Specifically, there are the finely divided, cationic or amphoteric, aqueous polymer dispersions and their method of preparation in the aforementioned literature, to which reference is expressly made at this point. The at least one aqueous dispersion of a polymer sizing agent (b) is used in the inventive method for reducing deposits in the dryer section in the production of paper, for example in an amount of 0.005 to 5.0 wt .-%, preferably 0.01 to 1 wt. %, particularly preferably 0.05 to 0.5% by weight, in each case based on the solids content of the paper stock.

In the method according to the invention, the order of addition of the components (a) and (b) is arbitrary, wherein the components can be added individually or in mixture to the fiber suspension.

For example, in the process according to the invention, first the water-soluble cationic polymer (a) is metered into the pulp. The addition may be made to the thick material (fiber concentration> 15 g / l, for example in the range of 25 to 40 g / l up to 60 g / l) or preferably in the thin material (fiber concentration <15 g / l, eg in the range of 5 to 12 g / l). The point of addition is preferably in front of the screens, but it can also be between a shearing stage and a screen or afterwards.

The aqueous dispersion of a polymer sizing agent (b) is usually added to the paper stock only after the addition of the water-soluble cationic polymer (a), but it can also be added to the paper stock at the same time and also in admixture with (a). Furthermore, it is also possible first to add the aqueous dispersion of a polymer sizing agent (b), followed by metering of the water-soluble cationic polymer (a).

In the process of the invention, the process chemicals commonly used in papermaking can be used in the usual amounts, e.g. Retention aids, dehydrating agents, other dry strength agents such as starch, pigments, fillers, optical brighteners, defoamers, biocides and paper dyes.

The process according to the invention is suitable for the reduction of all types of contaminants in the dryer section, in particular resin residues in the fiber suspension, papermaking auxiliaries, adhesives, binders from paper coating and binders from printing inks. Such contaminants or stickies whose deposits in the dryer section are significantly reduced by the process according to the invention are described, for example, in US Pat. No. 6,387,215 B1, column 2, from line 22 to column 3, line 26.

The present invention also provides the papers produced by the process described above, as well as cardboard and paperboard. For papermaking, suitable fibrous materials for the production of the pulps are all qualities customary for this purpose, eg wood pulp, bleached and unbleached pulp and pulps from all annual plants. Wood pulp includes, for example, groundwood, thermo-mechanical pulp (TMP), chemo-thermo-mechanical pulp (CTMP), pressure groundwood, semi-pulp, high yield pulp and refiner mechanical pulp (RMP). As pulp, for example, sulphate, sulphite and soda pulps come into consideration. For example, one uses unbleached pulp, which is also referred to as unbleached Kraftze I Istoff. Suitable annual plants for the production of paper materials are for example rice, wheat, sugarcane and kenaf.

The inventive method is particularly suitable for the production of papers from waste paper (including deinked waste paper), which is used either alone or in admixture with other fibers. It is also possible to start with fiber mixes of a primary material and recycled coated broke, e.g. bleached pine sulfate in admixture with reclaimed coated broke. The method according to the invention is of technical interest for the production of paper, board and cardboard from waste paper and, in special cases, also from deinked waste paper, because it significantly increases the runnability of the paper machines by reducing deposits and consequently fewer tears.

The pH of the stock suspension is, for example, in the range of 4.5 to 8, usually 6 to 7.5. To adjust the pH, it is possible to use, for example, an acid, such as sulfuric acid or aluminum sulphate.

The invention will be further illustrated by the following non-limiting examples.

Examples

The percentages in the examples are by weight unless otherwise specified.

The following polymers were used in the examples and comparative examples:

Polymer K1

Cationic polyethyleneimine, Molekukargewicht approximately 1 200 000 Dalton (Catiofast® ^® SF from BASF SE)

Polymer K2

Cationic polyvinylamine, hydrolysis 100 mol%, molecular weight about 400,000 Daltons (Catiofast® ^® VFH from BASF SE) Polymer K3

Cationic polyamine (epichlorohydrin dimethylamine condensate), molecular weight about 100,000 Daltons (Catiofast® ^® 8154 from BASF SE)

Polymer K4

Cationic polydiallyldimethylammonium chloride, molecular weight approx.

100,000 Dalton (Catiofast® ^® CS from BASF SE)

Polymer K5

Cationic polyacrylamide, molecular weight approximately 8 000 000 Dalton (Catiofast® ^® 8356 from BASF SE)

Polymer K6 Cationic polyvinylamine, Hofmann degradation product, molecular weight approx.

20,000 daltons, solids content 24.2% by weight, viscosity 19 mPas (determined with a

Brookfield viscosimeter LVT, spindle 1, 60 rpm, 20 ⁰ C), charge density of 57.2 meq / g per 100 g of products (as determined by Polyelektrolyttritration) (RSL HF 70D of the company

SNF SAS)

Polymer A1

Cationic dispersion of a Polymerleimungsmittels styrene-acrylate (Ba soplast ^® 270 D from BASF SE)

Preparation of the paper stock and sheet formation for the examples and comparative examples

A mixture of 50% newspaper printing and 50% label printing paper was pitched with drinking water at a consistency of 4% in a laboratory pulper at 40 ⁰ C for 25 min without specks and then diluted with water to a solids content of 0.5%.

To this stock were added the above-mentioned polymers with stirring (500 rpm), each with a contact time of 30 s. The metering of the polymers and the metered amounts (in percent by weight, based on the solids content of the stock used) are indicated in the Tables in each case. After the last addition of a polymer to the stock, as much stock was removed (approximately 500 mL) to produce a sheet having a basis weight of 80 g / m ² on a Rapid-Kothen sheet former. The leaves were, as usual in the Rapid-Köthen method, abgegautscht. Subsequently, the still wet sheet was unrolled and placed moist on a stainless steel screen whose weight was previously determined, with a pore size of 100 microns. Each of these sheets was on the stainless steel screen for 10 minutes dried in a laboratory drying cylinder at 90 ⁰ C.

For the quantitative determination of the deposits, the following method was used:

Strips with a dimension of 200 x 55 mm were cut out of the leaves on the stainless steel screen. These were subjected to a tear propagation peel test in a Zwick Roell Z module with the paper web and wire drawn at opposite speeds from each other at a speed of 400 mm / min. The adhesion energy in J / m ^{2 was} determined as a characteristic quantity. In addition, the proportion of deposits remaining on the sieve was determined by weighing the stainless steel sieve. The aim was to find as little as possible deposits on the sieve and at the same time to have the lowest possible adhesion to the sieve. Therefore, the following two parameters were used to characterize the samples:

% Reduction of the adhesion energy = (energy of a sample - energy of an untreated sample) / energy of an untreated sample [each in J / m ² ]

% Reduction of deposits = (deposition on a sample - deposition on a non-treated sample) / deposition on an untreated sample [in each case in g]

Tabellei: reduction of the adhesion energy

Table 1 shows the synergistic effect of the (a) water-soluble cationic polymer with the (b) aqueous dispersion of the polymer sizing agent with respect to the reduction of the adhesion energy.

Table 2: Reduction of deposits

Table 2 shows the efficiency and synergistic effect of the combination of a (a) water-soluble cationic polymer with a (b) aqueous dispersion of a polymer sizing agent, in particular by comparing Comparative Examples 8 and 9 with Example 9 according to the invention.

In addition, a comparison of Examples 6, 7 and 8 according to the invention with Examples 9, 10 and 11 according to the invention shows that the reduction of the adhesion energy runs parallel to the reduction of the deposits.

Claims

claims

1. A process for the reduction of deposits in the dryer section in the production of paper, paperboard and cardboard, which comprises adding (a) at least one water-soluble cationic polymer and (b) at least one aqueous dispersion of a polymer sizing agent to a paper stock, The paper stock is dewatered with sheet formation and the paper products dried.

2. The method according to claim 1, characterized in that the water-soluble cationic polymer (a) is selected from the group of vinylamine units containing polymers, cationic homo- and copolymers of (meth) acrylamide, polyallylamines, polyaminoalkyl vinyl ethers, reacted with Epihalohydrin Polyamidoaminverbindungen and polyamine compounds, amphoteric polymers having a total cationic charge, polymers containing ethyleneimine units, and homopolymers containing cationic or protonatable

Groups.

3. The method according to claim 2, characterized in that the vinylamine units containing polymers used as reaction products, which are available

by polymerizing at least one monomer of the formula

in which R ¹ , R ² = H or C ₁ - to C ₆ -alkyl,

and subsequent partial or complete cleavage of the groups - CO-R ¹ from the polymerized in the polymer units of the monomers (I) to form amino groups

and or

by Hofmann degradation of polymers having acrylamide and / or methacrylamide units.

4. The method according to claim 2, characterized in that as ethyleneimine units containing polymers at least one water-soluble cationic polymer from the group of Homopolymers of ethyleneimine, polyethylenimines reacted with at least bifunctional crosslinkers, polyamidoamines grafted with ethyleneimine and reacted with at least bifunctional crosslinkers,

Michael addition products of polyethyleneimines to ethylenically unsaturated acids, salts, esters, amides or nitriles of monoethylenically unsubstituted carboxylic acids, phosphonomethylierten Polyethylenimine, carboxylated polyethyleneimines and alkoxylated polyethyleneimines

starts.

5. The method according to claim 1, characterized in that is used as an aqueous dispersion of a polymer sizing agent (b) is a finely divided, cationic or amphoteric aqueous polymer dispersion, which is obtainable by a two-stage polymerization, wherein in the first polymerization a prepolymer is prepared and then an emulsion polymerization is carried out in an aqueous solution of this prepolymer in the presence of ethylenically unsaturated monomers.

6. The method according to claim 4, characterized in that the prepolymer is obtainable by solution polymerization of

(i) nitrogenous monomers containing an amino group and / or quaternary

Carry ammonium group, (ii) nonionic, hydrophobic, ethylenically unsaturated monomers,

(iii) optionally acid group-containing ethylenically unsaturated monomers, and

(iv) optionally nonionic, hydrophilic, ethylenically unsaturated monomers,

and this prepolymer is then subjected to an emulsion polymerization in the presence of ethylenically unsaturated monomers, wherein a monomer mixture of nonionic, hydrophobic, ethylenically unsaturated monomers is used as ethylenically unsaturated monomers.

7. The method according to any one of the preceding claims, characterized in that the components (a) and (b) are added in any order or as a mixture of the pulp.