EP1727937A1

EP1727937A1 - Aqueous dispersions of reactive gluing agents, method for the production and the use thereof

Info

Publication number: EP1727937A1
Application number: EP05707645A
Authority: EP
Inventors: Johann Bonn; Roland Ettl; Klaus Lorenz
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2004-03-01
Filing date: 2005-02-26
Publication date: 2006-12-06
Anticipated expiration: 2025-02-26
Also published as: JP2007525607A; CA2558148A1; US20070167558A1; CN1926283A; PT1727937E; JP4589379B2; EP1727937B1; WO2005083174A1; ES2462340T3; CA2558148C; KR20060134139A; DE102004010447A1; US8633274B2; KR101186382B1

Abstract

The invention relates to aqueous dispersions of reactive gluing agents which contain polymers comprising cationic vinylamine unites in the form of a protective colloid, wherein said protective colloid contains at least 0.0001 % by weight of diketen with respect thereto.

Description

Aqueous dispersion of reactive sizing agents, process for their preparation and their use

description

The invention relates to aqueous dispersions of reactive sizing agents which contain polymers containing vinylamine units as the protective colloid, the protective colloid containing less than 0.0001% by weight, based on the protective colloid, of diets. Furthermore, the invention relates to a method for producing the aqueous dispersions, their use for sizing paper, cardboard and cardboard, and a method for sizing paper, cardboard and cardboard.

Aqueous alkyldiketene dispersions, which are stabilized with cationic starch or with anionic emulsifiers, are commercially available bulk sizes for paper. The full sizing effect of the papers glued with alkyldiketene dispersions only develops when the glued papers are stored. Such papers cannot therefore be processed immediately after paper production, e.g. finished with coating colors, or printed. Rather, they have to be stored for at least 24 hours until a sufficient sizing effect develops. However, it is known from the literature that cationic polymers increase the rate of sizing.

Although the usual size dispersions containing cationic polymers increase the speed of size formation, they are often not stable in storage over a long period of time.

DE-A-3316 179 describes AKD dispersions which contain polymers containing ethyleneimine units and a water-soluble dicyandiamide-formaldehyde condensation product. The latter increases the speed of sizing (so-called promoter effect), but does not help stabilize the dispersion.

From US-A-3,223,544 as well as from EP-A-0353212 alkyldiketene (AKD) - dispersions with cationic starch as a protective colloid and an anionic dispersant as a stabilizer are known.

AKD dispersions are known from WO-A-96/26318 which contain either copolymers of N-vinylpyrrolidone and N-vinylimidazole or condensation products based on polyethyleneimines as protective colloids. The production of these AKD dispersions is very complex due to the copolymerization or condensation of the protective colloids. The use of polymers containing vinylamine units as promoters for mass sizing in starch-containing AKD dispersions is known from the earlier German patent application with the file number 10237911.4.

The older German patent application with the file number 10237912.2 discloses a process for the mass sizing of paper, in which a reactive sizing agent, a retention aid and a cationic polymer, which is selected from polymers containing vinylamine units, polymers containing vinylguanadine units, polyethyleneimines, polyamidoamines grafted with ethyleneimine and polydiallyl dimethylammonium , are added to the aqueous slurry of cellulose fibers. In this case, the cationic polymers are added separately from the reactive sizing agents, or the components are metered in together without, however, a dispersion having been prepared beforehand from the components.

From WO-A-98/41565 AKD dispersions are known which, as protective colloid, are reaction products of polymers containing amino groups from the group of polymers containing vinylamine units, polyamidoamines and polymaidoamines grafted with polyethyleneimine with diketenes in the weight ratio of polymer to diketene of 10,000 : 1 to 1: 3 included. However, the production of the protective colloid is very complex.

The object of the present invention was to provide improved aqueous dispersions of reactive sizing agents which are easier to produce and which have both an increased rate of sizing formation and adequate storage stability compared to the prior art.

The object is achieved according to the invention with aqueous dispersions of reactive sizing agents which contain polymers containing cationic vinylamine units as the protective colloid, the protective colloid containing less than 0.0001% by weight, based on the protective colloid, of diketenes. Diketenes in this sense are understood to be the C 1-4 alkyl ketene dimers described in more detail below.

Aqueous dispersions whose protective colloids are essentially free from diketenes are preferred, and those whose protective colloids are completely free from diketenes are particularly preferred.

Also preferred are aqueous dispersions which generally contain less than 0.0001% by weight of reactive sizing agent; Reactive sizing agents include, in addition to the C ₂ to C ₂₂ alkyl ketene dimers, the C ₅ to C ₂₂ alkyl or C ₅ to C ₂₂ alkenyl succinic anhydrides described below, C ₁₂ to C ₃₆ alkyl isocyanates, understood organic isocyanates and / or mixtures thereof. Aqueous dispersions whose protective colloids are essentially free of reactive sizing agents are preferred, and those whose protective colloids are completely free of reactive sizing agents are particularly preferred.

Those aqueous dispersions which contain less than 1% by weight, based on the aqueous dispersion, of cationic starch are also preferred.

Those aqueous dispersions which are essentially free of cationic starch are particularly preferred, and those which are completely free of cationic starch are particularly preferred.

According to the invention, at least one polymer containing vinylamine units is used as a protective colloid for the reactive sizing agent in the aqueous dispersions according to the invention. The amount of cationic polymers is, for example, 10 to 100% by weight, preferably 15 to 75% by weight, particularly preferably 20 to 50% by weight, based on the reactive sizing agent.

Polymers containing vinylamine units are known, cf. US-A-4,421, 602, US-A-5,334,287, EP-A-0216387, US-A-5,981, 689, WO-A-00/63295 and

US-A-6,121,409. They are produced by hydrolysis of open-chain polymers containing N-vinylcarboxylic acid amide units. These polymers are e.g. obtainable by polymerizing N-vinylformamide, N-vinyl-N-methylformamide, N-vinyl-acetamide, N-vinyl-N-methylacetamide, N-vinyl-N-ethylacetamide and N-vinylpropionamide. The monomers mentioned can be polymerized either alone or together with other monomers.

Suitable monoethylenically unsaturated monomers which are copolymerized with the N-vinylcarboxamides are all compounds which can be copolymerized therewith. Examples include vinyl esters of saturated carboxylic acids of 1 to 6 carbon atoms such as vinyl formate, vinyl acetate, vinyl propionate and vinyl butyrate and vinyl ethers such as C to C ₆ alkyl vinyl ether, for example methyl or ethyl vinyl ether. Further suitable comonomers are esters, amides and nitriles of ethylenically unsaturated C ₃ to C ₆ carboxylic acids, for example methyl acrylate, methyl methacrylate, ethyl acrylate and ethyl methacrylate, acrylamide and methacrylamide and also acrylonitrile and methacrylonitrile.

Further suitable carboxylic acid esters are derived from glycols or polyalkylene glycols, only one OH group being esterified in each case, for example hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate and acrylic acid mono mass of polyalkylene glycol 500 to 10,000. Other suitable comonomers are esters of ethylenically unsaturated carboxylic acids with amino alcohols such as as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, diethylaminopropyl acrylate, dimethylaminobutyl acrylate and diethylaminobutyl acrylate. The basic acrylates can be used in the form of the free bases, the salts with mineral acids such as hydrochloric acid, sulfuric acid or nitric acid, the salts with organic acids such as formic acid, acetic acid, propionic acid or the sulfonic acids or in quaternized form. Suitable quaternizing agents are, for example, dimethyl sulfate, diethyl sulfate, methyl chloride, ethyl chloride or benzyl chloride.

Other suitable comonomers are amides of ethylenically unsaturated carboxylic acids such as acrylamide, methacrylamide and N-alkyl mono- and diamides of monoethylenically unsaturated carboxylic acids with alkyl radicals of 1 to 6 carbon atoms, e.g. N-methyl acrylamide, N, N-dimethylacrylamide, N-methyl methacrylamide, N-ethyl acrylamide, N-propyl acrylamide and tert-butyl acrylamide as well as basic (meth) acrylamides, such as e.g. Dimethylaminoethyl acrylamide, dimethylaminoethyl methacrylamide, diethylaminoethyl acrylamide, diethylaminoethyl methacrylamide, dimethylaminopropylacrylamide, diethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide and diethylaminopropyl methacrylamide.

Also suitable as comonomers are N-vinylpyrrolidone, N-vinylcaprolactam, acrylonitrile, methacrylonitrile, N-vinylimidazole and substituted N-vinylimidazoles such as e.g. N-vinyl-2-methylimidazole, N-vinyl-4-methylimidazole, N-vinyl-5-methylimidazole, N-vinyl-2-ethylimidazole and N-vinylimidazolines such as N-vinylimidazoline, N-vinyl-2-methylimidazoline and N-vinyl-2-ethylimidazoline. In addition to the free bases, N-vinylimidazoles and N-vinylimidazolines are also used in neutralized or in quaternized form with mineral acids or organic acids, the quaternization preferably being carried out with dimethyl sulfate, diethyl sulfate, methyl chloride or benzyl chloride. Diallyldialkylammonium halides such as e.g. Diallyldimethylammonium chloride.

The copolymers contain, for example

95 to 5 mol%, preferably 90 to 10 mol% of at least one N-vinylcarbonamide and

5 to 95 mol%, preferably 10 to 90 mol% of other monoethylenically unsaturated monomers copolymerizable therewith

in polymerized form. The comonomers are preferably free from acid groups. In order to prepare polymers containing vinylamine units, one preferably starts from homopolymers of N-vinylformamide or from copolymers which are obtained by copolymerizing

- N-vinylformamide with

Vinyl formate, vinyl acetate, vinyl propionate, acrylonitrile, N-vinyl caprolactam, N-vinyl urea, N-vinyl pyrrolidone or C to C ₆ alkyl vinyl ethers

and subsequent hydrolysis of the homo- or the copolymers to form vinylamine units from the polymerized N-vinylformamide units, the degree of hydrolysis being e.g. 1 to 100 mol%, preferably 25 to 100 mol%, particularly preferably 50 to 100 mol% and particularly preferably 70 to 100 mol%. The polymers described above are hydrolysed by known processes by the action of acids, bases or enzymes. When acids are used as hydrolysis agents, the vinylamine units of the polymers are in the form of the ammonium salt, while the free amino groups are formed in the hydrolysis with bases. The polymers containing vinylamine units can be used in the form of the free bases, the ammonium salts or also in quaternized form as a promoter.

In most cases, the degree of hydrolysis of the homopolymers and copolymers used is 90 to 95 mol%. The degree of hydrolysis of the homopolymers is synonymous with the vinylamine units in the polymers. In the case of copolymers which contain vinyl esters in copolymerized form, in addition to the hydrolysis of the N-vinylformamide units, hydrolysis of the ester groups can occur with formation of vinyl alcohol units. This is particularly the case if the copolymers are hydrolysed in the presence of sodium hydroxide solution. Polymerized acrylonitrile is also chemically changed during the hydrolysis. This creates, for example, amide groups or carboxyl groups. The homo- and copolymers containing vinylamine units can optionally contain up to 20 mol% of amidine units, which are formed, for example, by reaction of formic acid with two adjacent amino groups or by intramolecular reaction of an amino group with a neighboring amide group, for example of polymerized N-vinylformamide. The average molecular weights M w of the polymers containing vinylamine units are, for example, 500 to 10 million, preferably 750 to 5 million and particularly preferably 1,000 to 2 million (determined by light scattering). This molar mass range corresponds, for example, to K values of 30 to 150, preferably 60 to 90 (determined according to H. Fikentscher in 5% aqueous saline solution at 25 ° C., a pH of 7 and a polymer concentration of 0.5% by weight ). Cationic polymers which have K values of 85 to 90 are particularly preferably used. The polymers containing vinylamine units are preferably used in salt-free form. Salt-free aqueous solutions of polymers containing vinylamine units can be prepared, for example, from the salt-containing polymer solutions described above with the aid of ultrafiltration on suitable membranes at separation limits of, for example, 1,000 to 500,000 daltons, preferably 10,000 to 300,000 daltons.

Derivatives of polymers containing vinylamine units can also be used as cationic polymers. For example, it is possible to obtain from the polymers containing vinylamine units by amidation, alkylation, sulfonamide formation,

Urea formation, thiourea formation, carbamate formation, acylation, carboxymethylation, phosphonomethylation or Michael addition of the amino groups of the polymer to produce a large number of suitable derivatives. Of particular interest here are uncrosslinked polyvinylguanidines which are obtained by reacting polymers containing vinylamine units, preferably polyvinylamines, with cyanamide (R ¹ R ² N-CN, where R \ R ² = H, C to C ₄ alkyl, C ₃ to C ₆ -cycloalkyl, phenyl, benzyl, alkyl-substituted phenyl or naphthyl) are accessible, cf. US-A-6,087,448, column 3, line 64 to column 5, line 14.

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 an aqueous medium in the presence of at least one of the graft bases mentioned, together with copolymerizable other monomers, and then hydrolyzing the grafted vinylformamide units to vinylamine units in a known manner.

Polymers containing vinyl amine units that are preferred are vinyl amine homopolymers with a degree of hydrolysis of 1 to 100 mol%, preferably 25 to 100 mol%, and 1 to 100 mol%, preferably 25 to 100 mol%, of hydrolysis Copolymers of vinyl formamide and vinyl acetate, vinyl alcohol, vinyl pyrrolidone or acrylamide, each with K values from 30 to 150, in particular 60 to 90.

The polymers containing vinylamine units are used in the aqueous dispersions according to the invention as protective colloids for reactive sizing agents in order to obtain aqueous sizing agent dispersions which have both an increased rate of sizing formation and sufficient storage stability.

Suitable reactive sizing agents for the dispersions according to the invention are, for example, C ₁₂ to C ₂₂ alkyl ketene dimers, C ₅ to C ₂₂ alkyl or C ₅ to C ₂₂ alkenyl succinic anhydrides, C ₁₂ to C ₃₆ alkyl isocyanates and / or organic isocyanates such as dodecyl isocyanate, octadecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, eicosyl isocyanate and decyl isocyanate. Bulk sizing agents that are preferably used are alkyl ketene dimers and long-chain alkyl or alkenyl succinic anhydrides.

Examples of alkylketene dimers are tetradecyldiketene, stearydiketene, lauryldiketene, palmityldiketene, oleyldiketene, behenyldiketene or mixtures thereof. In addition, alkyldiketenes with different alkyl groups such as stearylpalmityldiketene, behenylstearyldiketene, behenyloleyldiketene or palmitylbehenyldiketene are suitable. Stearyldiketene, palmityldiketene, behenyldiketene or mixtures of behenyldiketene and stearyldiketene are preferably used. Substituted succinic anhydrides suitable as reactive sizing agents are, for example, decenyl succinic anhydride, n-octa-decenyl succinic anhydride, dodecenyl succinic anhydride and n-hexadecenyl succinic anhydride.

The aqueous dispersions according to the invention usually have a reactive sizing agent content of 1 to 50% by weight, based on the total weight of the dispersion. For example, the dispersions have a content of 1 to 50% by weight, preferably 5 to 35% by weight, based on the total weight of the dispersion ₂ to C ₂₂ alkyl diketenes. When using C ₅ to C ₂₂ alkyl or C ₅ to C ₂₂ alkenyl succinic anhydrides, their content is, for example, 1 to 25% by weight, preferably 2 to 10% by weight, based on the total weight of the dispersion ,

The alkyl diketenes and long-chain alkenyl or alkyl succinic anhydrides which are preferably suitable as sizing agents and processes for the preparation of anionically adjusted aqueous dispersions of such reactive sizing agents are known from WO-A-00/23651, cf. Pages 2 to 12. To produce size dispersions, the reactive sizes are usually heated to a temperature above their melting point and emulsified in molten form in water under the action of shear forces. The liquid alkenyl succinic anhydride can be emulsified at room temperature. For this you use e.g. Homogenizers. In order to stabilize the dispersed sizing agents in the aqueous phase, at least one anionic dispersing agent from the group of the condensation products is used

(a) Naphthalenesulfonic acid and formaldehyde

(b) phenol, phenolsulfonic acid and formaldehyde,

(c) naphthalenesulfonic acid, formaldehyde and urea and

(d) phenol, phenol sulfonic acid, formaldehyde and urea. The anionic dispersants can be in the form of the free acids, the alkali metal, alkaline earth metal and / or the ammonium salts. The ammonium salts can be derived from ammonia as well as from primary, secondary and tertiary amines, for example the ammonium salts of dimethylamine, trimethylamine, hexylamine, cyclohexylamine, dicyclohexylamine, ethanolamine, diethanolamine and triethanolamine are suitable. The condensation products described above are known and commercially available. They are prepared by condensing the constituents mentioned, it being possible to use the corresponding alkali metal, alkaline earth metal or ammonium salts instead of the free acids. Acids such as sulfuric acid, p-toluenesulfonic acid and phosphoric acid are suitable as catalysts in the condensation. Naphthalenesulfonic acid or its alkali metal salts are preferably condensed with formaldehyde in a molar ratio of 1: 0.1 to 1: 2 and mostly in a molar ratio of 1: 0.5 to 1: 1. The molar ratio for the production of condensates from phenol, phenolsulfonic acid and formaldehyde is also in the range given above, any mixtures of phenol and phenolsulfonic acid being used instead of naphthalenesulfonic acid in the condensation with formaldehyde. Instead of phenolsulfonic acid, one can also use the alkali metal and ammonium salts of phenolsulfonic acid. The condensation of the starting materials specified above can optionally also be carried out in the presence of urea. For example, based on naphthalenesulfonic acid or on the mixture of phenol and phenolsulfonic acid, 0.1 to 5 moles of urea are used per mole of naphthalenesulfonic acid or per mole of the mixture of phenol and phenolsulfonic acid.

The condensation products have, for example, molar masses in the range from 800 to 100,000, preferably 1,000 to 30,000 and in particular 4,000 to 25,000. Preferred anionic dispersants are salts which are obtained, for example, by neutralizing the condensation products with lithium hydroxide, sodium hydroxide, Potassium hydroxide or ammonia. The pH of the salts is, for example, in the range from 7 to 10.

Other suitable anionic dispersants are lignin sulfonic acid and its alkali metal, alkaline earth metal or ammonium salts.

Amphiphilic copolymers are also suitable as anionic dispersants

(i) hydrophobic monoethylenically unsaturated monomers and

(ii) hydrophilic monomers with an anionic group such as monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated sulfonic acids, monoethylenically unsaturated phosphonic acids or mixtures thereof. Suitable hydrophobic monoethylenically unsaturated monomers

(a) are, for example, olefins with 2 to 150 C atoms, styrene, α-methylstyrene, ethylstyrene, 4-methylstyrene, acrylonitrile, methacrylonitrile, esters of monoethylenically unsaturated C ₃ to C ₅ carboxylic acids and monohydric alcohols, amides Acrylic acid or methacrylic acid with d to C ₂ alkyl amines, vinyl esters of saturated monocarboxylic acids with 2 to 24 C atoms, diesters of maleic or fumaric acid with monohydric C to C ₂₄ alcohols, vinyl ethers of alcohols with 3 to 24 C atoms or mixtures of the connections mentioned.

The amphiphilic copolymers contain, as hydrophilic monomers (b), for example C ₃ - to C-monoethylenically unsaturated carboxylic acids or their anhydrides, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, vinylphosphonic acid, salts of the monomers mentioned or mixtures thereof as hydrophilic monomers polymerized with an anionic group.

Aqueous size dispersions which are amphiphilic copolymers as anionic dispersants are particularly preferred

(a) olefins with 4 to 12 carbon atoms, styrene or mixtures thereof as hydrophobic monomers and

(b) Maleic acid, acrylic acid, methacrylic acid, half esters of maleic acid and alcohols with 1 to 25 carbon atoms or alkoxylation products of such alcohols, half amides of maleic acid, salts of the monomers mentioned or mixtures of these compounds as hydrophilic monomers with an anionic group

contain polymerized and have a molecular weight Mw of 1,500 to 100,000.

Preferred anionic dispersants are copolymers of maleic anhydride with C ₄ to C ₁₂ olefins, particularly preferably C ₈ olefins such as octene-1 and diisobutene. Diisobutene is very particularly preferred. The molar ratio between maleic anhydride and olefin is, for example, in the range from 0.9: 1 to 3: 1, preferably from 0.95: 1 to 1.5: 1. These copolymers are preferably used in hydrolyzed form as aqueous solutions or dispersions, where the anhydride group is open and the carboxyl groups are preferably partially or completely neutralized. The following bases are used for neutralization: alkali metal bases, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, alkaline earth metal salts, such as calcium hydroxide, calcium carbonate, magnesium hydroxide, ammonia, primary, secondary or tertiary amines such as triethylamine, triethanolamine, diethanolamine, ethanolamine, morpholine etc.

If the amphiphilic copolymers are not sufficiently water-soluble in the form of the free acid, they are used in the form of water-soluble salts, e.g. the corresponding alkali metal, alkaline earth metal and ammonium salts are used. The molecular weight Mw of the amphiphilic copolymers is, for example, 800 to 250,000, mostly 1,000 to 100,000 and is preferably in the range from 3,000 to 20,000, in particular from 1,500 to 10,000. The acid numbers of the amphiphilic copolymers are, for example, 50 to 500, preferably 150 to 300 mg KOH / g polymer.

The amphiphilic copolymers are e.g. in amounts of 0.05 to 20, preferably 0.5 to 10% by weight, based on the reactive sizing agent, used as the anionic dispersant for the production of the sizing agent dispersions. The amphiphilic copolymers are preferably used in amounts of 0.1 to 2, in particular 0.6 to 1,% by weight, based on the sizing agent to be dispersed.

The content of anionic dispersants in the aqueous dispersion is, for example, 0.01 to 5% by weight, preferably 0.01 to 2.5% by weight and very particularly preferably 0.01 to 1% by weight.

The aqueous dispersions according to the invention can contain further components, such as, for example, non-cellulose-reactive hydrophobic substances which contribute to improving stability and, for example, in EP-A-437764 and

EP-A-658228. Examples of suitable non-cellolulose-reactive substances are fatty acids, amides and esters and waxes. Examples of these without claiming to be complete are stearic acid behenyl esters, myristic acid stearyl esters, stearic acid isododececyl esters, carbonic acid diolyl ester, carbonic acid leyl stearyl esters, oleyl-N, N-distearyl urethane, paraffin, di-oleic acid glycerol esters, tris oleic acid glycerol esters and tris oleic acid glycerol esters.

Furthermore, finely divided, aqueous polymer dispersions, which are a sizing agent for paper, can additionally be contained in the dispersions according to the invention. Such polymer dispersions are known, for example, from EP-B-0051 144

EP-B-0257412, EP-B-0276770, EP-B-0058313 and EP-B-0 150 003 are known. Such polymer dispersions which act as paper sizes are obtainable, for example, by mixing 1 to 32 parts by weight of a mixture

(a) styrene, acrylonitrile and / or methacrylonitrile, (b) Acrylic acid and / or methacrylic acid esters of d to C ₁₈ alcohols and / or vinyl esters of saturated C ₂ to C ₄ carboxylic acids and optionally

(c) other monoethylenically unsaturated copolymerizable monomers

polymerized in aqueous solution in the presence of 1 part by weight of a solution copolymer as described in WO-A-96/31650 and the literature cited therein.

Monomers of group (a) are styrene, acrylonitrile, methacrylonitrile or mixtures of styrene and acrylonitrile or of styrene and methacrylonitrile. The monomers of group (b) used are acrylic acid and / or methacrylic acid esters of C to C ₁₈ alcohols and / or vinyl esters of saturated C ₂ to C ₄ carboxylic acids. Preferably used as the monomer of group (b) are butyl acrylate and butyl methacrylate, for example isobutyl acrylate, n-butyl acrylate and isobutyl methacrylate. Monomers of group (c) are, for example, butadiene, isoprene, C ₃ - to C ₅ -monoethylenically unsaturated carboxylic acids, acrylamidomethyl propanesulfonic acid, sodium vinyl sulfonate, vinyl imidazole, N-vinyl formamide, acrylamide, methacrylamide, N-vinyl imidazoline and cationic polymers such as dimethylaminopropyl methacrylamide or dimethylaminoethyl methochloride. 1 to 32 parts by weight of a monomer mixture of components (a) to (c) are used per 1 part by weight of the copolymer. The monomers of components (a) and (b) can be copolymerized in any ratio, for example in the molar ratio 0.1: 1 to 1: 0.1.

If necessary, the monomers of group (c) are used to modify the properties of the copolymers.

Details on the preparation of these additional polymer dispersions can be found in WO-A-96/31650 and the literature cited therein.

If these polymer dispersions are used in the aqueous dispersions of reactive sizing agents according to the invention, preference is given to those which contain cationic polymers such as dimethylaminopropyl methacrylamide and / or dimethylaminoethyl acrylate in combination with styrene, acrylonitrile, butadiene and / or acrylic acid esters.

When such polymer dispersions are used, their content is generally 25 to 300% by weight, preferably 50 to 250% by weight and particularly preferably 75 to 200% by weight, based on the reactive sizing agent.

The invention furthermore relates to a process for the preparation of the aqueous dispersions of reactive sizes according to the invention. For example, an aqueous solution of a polymer containing vinylamine units, at least one anionic dispersant and optionally further components such as non-cellulose-reactive hydrophobic substances and the polymer dispersions mentioned can be introduced and the reactive sizing agent therein at temperatures of, for example, 20 to 100, preferably 40 to 90 ° C. disperse. The sizing agent is preferably added in the form of a melt and dispersed with vigorous stirring or shearing. In another variant, the sizing agent is first converted into an emulsion with the anionic dispersant. Then an aqueous solution of a polymer containing vinylamine units is added and the emulsification step is repeated. The dispersions are produced in apparatuses known to the person skilled in the art, such as, for example, high-pressure homogenizers, colloid mills and ultrasonic dispersers. The resulting dispersion is cooled in each case. In this way it is possible, for example, to prepare aqueous sizing agent dispersions which contain 0.1 to 65% by weight, preferably 1 to 50% by weight and particularly preferably 5 to 35% by weight of an alkyl diketene or 0.1 to 65% by weight .-%, preferably 1 to 50 wt .-%, particularly preferably 1 to 25 wt .-% and in particular 2 to 10 wt .-% of an alkenyl succinic anhydride as dispersant.

Such highly concentrated sizing agent dispersions have a relatively low viscosity, e.g. in the range of 20 to 1,000 mPas (measured with a Brookfield viscometer and a temperature of 20 ° C). In the preparation of the aqueous dispersions, the pH is, for example, from 2 to 8 and is preferably in the range from 3 to 4. Aqueous sizing agent dispersions are generally obtained with an average particle size of the sizing agents in the range from 100 to 3000 nm. preferably 250 to 2,000 nm. However, depending on the choice of the protective colloid and the anionic dispersant, the average particle sizes can also be less than 100 nm, for example between 50 and 100 nm, or larger than 3,000 nm, for example up to 4 μm.

The dispersions according to the invention are used as mass sizing agents in the production of paper, cardboard and cardboard. Paper, cardboard and cardboard are usually produced by dewatering a slurry of cellulose fibers. Suitable cellulose fibers are all the common types, for example cellulose fibers made from wood pulp and all fibers obtained from annual plants. For example, wood pulp includes wood pulp, thermomechanical material (TMP), chemothermomechanical material (CTMP), pressure sanding, semi-pulp, high-yield pulp and refiner mechanical pulp (RMP) as well as waste paper. Also suitable are pulps that can be used in bleached or unbleached form. Examples of these are sulfate, sulfite and sodium pulp. Unbleached pulps, which are also referred to as unbleached kraft pulp, are preferably used. The fibers mentioned can be used alone or in a mixture. The pH of the cellulose fiber slurry is, for example, 4 to 8, preferably 6 to 8. The paper stock can be dewatered discontinuously or continuously on a paper machine.

After dewatering the paper stock and drying the paper product, mass-sized paper products such as paper, cardboard or cardboard are obtained with a basis weight of, for example, 20 to 400 g / m ² , preferably 40 to 220 g / m ² .

The paper stock is preferably additionally dewatered in the presence of a retention agent. In addition to anionic retention aids or nonionic retention aids such as polyacrylamides, cationic polymers are preferably used as retention aids and as drainage aids. This leads to a significant improvement in the runnability of the paper machines.

All commercially available products for this purpose can be used as cationic retention agents. These are, for example, cationic polyacrylamides, polydiallyldimethylammonium chlorides, high molecular weight polyvinylamines, high molecular weight polyvinylamines with K values of more than 150, polyethyleneimines, polyamines with a molecular weight of more than 50,000, modified polyamines grafted with ethyleneimine and optionally crosslinked, Polyetheramides, polyvinylimidazoles, polyvinylpyrrolidines, polyvinylimidazolines, polyvinyltetrahydropyrins, poly (dialkylaminoalkylvinylethers), poly (dialkylaminoalkyl (meth) acrylates) in protonated or in quaternized form, and also polyamidoamines from a dicarboxylic acid such as adipylene acid and polyamine such as diethylamine and polyamine, which are grafted with ethyleneimine and crosslinked with polyethylene glycol dichlorohydrin ethers in accordance with the teaching of DE-B-2434816 or with polyamidoamines which have been reacted with epichlorohydrin to form water-soluble condensation products and with copolymers of acrylamide or methacrylamide and dial kylaminoethyl acrylates or rhethacrylates, for example copolymers of acrylamide and dimethylaminoethyl acrylate in the form of the salt with hydrochloric acid or in a form quaternized with methyl chloride. Other suitable retention agents are so-called microparticle systems made from cationic polymers such as cationic starch and finely divided silica or from cationic polymers such as cationic polyacrylamide and bentonite.

The cationic polymers used as retention aids have, for example, K values according to Fikentscher of more than 150 (determined in 5% aqueous saline solution at a polymer concentration of 0.5% by weight, a temperature of 25 ° C. and a pH of 7). They are preferably used in amounts of 0.01 to 0.3% by weight, based on dry cellulose fibers. If necessary, further auxiliaries, as are known to the person skilled in the art from the literature, can be added to the paper stock before sheet formation. These are, for example, fixatives, solidifiers and defoamers.

Furthermore, the present invention relates to the use of the aqueous dispersions according to the invention described above as bulk sizes for the production of paper, cardboard and cardboard.

The following examples are intended to illustrate the invention without, however, restricting it.

Unless the context indicates otherwise, the percentages in the examples mean percent by weight. The K values were determined according to H. Fikentscher, Cellulose-Chemie, Vol. 13, 58-64 and 71-74 (1932) in 5% aqueous saline solution at a temperature of 25 ° C and a pH of 7 determined at a polymer concentration of 0.5 wt .-%. The molecular weights Mw of the polymers were measured by light scattering. The mean particle diameter of the dispersed particles of the polymer dispersions was determined both by Fraunhofer diffraction with a Coulter device of the type LS 230 with a small volume module and by electron microscopy. The viscosities were determined using a Brookfield viscometer at a temperature of 22 ° C.

Examples

Ink flotation time

The ink floating time (measured in minutes) is the time it takes a test ink according to DIN 53 126 to reach 50% through a test sheet.

Cobb value

The determination was made according to DIN 53 132 by storing the paper sheets in water for a period of 60 seconds. The water absorption is given in g / m ² .

edge penetration

The paper sheet is coated on both sides with an adhesive tape without streaks. Then strips with the dimensions 25 x 75 mm are cut. These test strips are immersed in a 30% hydrogen peroxide bath at 70 ° C or in a 3% lactic acid bath at 25 ° C. The edge penetration is determined by differential weighing of the dry test strips and the test strips immersed in the bath. Polyvinylamine 1

Cationic polymer obtained by hydrolysis of poly-N-vinylformamide with a K value of 90 and a degree of hydrolysis of 95 mol% (polymer containing 95 mol% vinylamine units and 5 mol% vinylformamide units) ,

Polyvinylamine 2

Cationic polymer obtained by hydrolysis of poly-N-vinylformamide with a K value of 75 and a degree of hydrolysis of 65 mol% (polymer containing 65 mol% vinylamine units and 35 mol% vinylformamide units) ,

Polyvinylamine 3

Cationic polymer obtained by hydrolysis of poly-N-vinylformamide with a K value of 110 and a degree of hydrolysis of 95 mol% (polymer containing 95 mol% vinylamine units and 5 mol% vinylformamide units) ,

Dispersion 1

76 g of an aqueous 8% by weight solution of polyvinylamine 1, adjusted to a pH of 3.7, were heated to a temperature of 75.degree. 3 g of a 5% by weight sodium salt of the condensation product of naphthalenesulfonic acid with formaldehyde in a molar ratio of 1: 0.8 and a molar mass Mw of 7000 were stirred in as an anionic dispersant using a high-speed stirrer. Then 12 g of stearyl diketene were also added with a high-speed stirrer. The resulting emulsion was homogenized using a high-pressure homogenizer at 170 bar and 75 ° C. and then quickly cooled with ice. The dispersion had a viscosity of 120 mPas and an average particle size of 1.6 / m at 22 ° C.

Dispersion 2

89 g of an aqueous 3% by weight solution of polyvinylamine 2, adjusted to a pH of 3.4, were heated to 75 ° C. 1.78 g of a 5% by weight lignin sulfonate sodium salt as an anionic dispersant were stirred in with a high-speed stirrer. Then 7 g of stearyl diketene were added using a high-speed stirrer. The resulting emulsion was homogenized using a high-pressure homogenizer at 190 bar and 75 ° C. and then quickly cooled with ice. The dispersion had a viscosity of 20 mPas and an average particle size of 0.98 μm at 22 ° C. Dispersion 3

68 g of an aqueous 8% by weight solution of polyvinylamine 3, adjusted to a pH of 3.6, were heated to a temperature of 75.degree. A rapid stirrer was used to stir in 2 g of a 5% by weight lignin sulfonate sodium salt as an anionic dispersant. Then 15 g of stearyl diketene were also added with a high-speed stirrer. The resulting emulsion was homogenized using a high-pressure homogenizer at 170 bar and 75 ° C. and then quickly cooled with ice. The dispersion had a viscosity of 120 mPas and an average particle size of 1.6 μm at 22 ° C.

Dispersion 4

20 g of the dispersion 1 were determined by means of an intensive with 12 g of a 30% strength by weight polymer dispersion prepared from the monomers styrene, butylacrylate and a cationic acrylamide (Basoplast 270D ^®), nm with an average particle size of 45, is mixed. The resulting dispersion had a viscosity of 700 mPas and an average particle size of 1.7 μm at 22 ° C.

Comparative dispersion 1

Example 1 from WO 6/26318

Comparative dispersion 2 sizing agent 2 from WO 98/41565

Application engineering examples

example 1

To a paper stock with a consistency of 8 g / l from a completely bleached mixture of 70% pine and 30% birch sulfate pulp with a freeness of 35 ° (Schopper-Riegler) was added, in each case based on dry cellulose fiber mixture, that in the see Table 1 indicated amounts of dispersions 1 to 4 and Comparative dispersions 1 and 2, 20 wt .-% calcium carbonate, 0.6 wt .-% of a cationic corn starch and 0.04 wt .-% of a cationic polyacrylamide (poly min ^® KE2020) as a retention agent. The pH of the mixtures was adjusted to 7. The mixtures were then processed on a Rapid-Koethen sheet former to form a sheet with a basis weight of 80 g / m ² . The sheet was then dried on a steam heated drying cylinder at a temperature of 90 ° C to a water content of 7%. The Cobb value of the leaves was determined immediately after drying. The leaves were then at 24 ° C for 24 hours stored at a relative humidity of 50%. The measurements were then repeated. The results obtained are shown in Table 1.

Table 1

Test Nos. 1 and 2 are comparative examples, and Tests 3 to 6 are examples according to the invention.

Example 2

To a paper stock with a consistency of 8 g / l of 100% waste paper, based in each case on dry cellulose fiber mixture, the amounts of dispersions 1 to 4 and comparative dispersions 1 and 2 given in Table 2, 0.6% by weight, were added cationic corn starch and 0.04% by weight of a cationic polyacrylamide (Polymin ^® KE2020) as a retention agent. The pH of the mixtures was adjusted to 7. The mixtures were then processed on a Rapid-Köthen sheet former to form a sheet with a basis weight of 100 g / m ² . The sheet was then dried on a steam heated drying cylinder at a temperature of 90 ° C to a water content of 7%. The leaves were then stored for 24 hours at 25 ° C and 50% relative humidity. The measurements were then repeated. The results obtained are shown in Table 2. Table 2

Test Nos. 7 and 8 are comparative examples, and Tests 9 to 12 are examples according to the invention.

Example 3

To a paper stock with a consistency of 8 g / l from a completely bleached mixture of 70% pine and 30% birch sulfate pulp with a freeness of 35 ° (Schopper-Riegler) was added, in each case based on dry cellulose fiber mixture, in Table 3 indicated amounts of dispersions 1 to 4 and Comparative dispersions 1 and 2, 20 wt .-% of calcium carbonate, 0.75 wt .-% of a cationic corn starch and 0.04 wt .-% of a cationic polyacrylamide (poly min ^® KE2020) as a retention aid , The pH of the mixtures was adjusted to 7. The mixtures were then processed on a Rapid-Köthen sheet former to form a sheet with a basis weight of 150 g / m ² . The sheet was then dried on a steam heated drying cylinder at a temperature of 90 ° C to a water content of 7%. The sheets were then coated on both sides with an adhesive tape without streaks. Strips measuring 25 x 75 mm were cut from the leaves. The test strips were immersed in a 30% hydrogen peroxide bath at 70 ° C or in a 3% lactic acid bath at 25 ° C. The edge penetration was determined by differential weighing. The results obtained are shown in Table 3. Table 3

Test Nos. 13 and 14 are comparative examples, Tests 15 to 18 are examples according to the invention.

Claims

claims

1. Aqueous dispersions of reactive sizing agents which contain polymers containing cationic vinylamine units as the protective colloid, characterized in that the protective colloid contains less than 0.0001% by weight, based on the protective colloid, of diketenes.

2. Aqueous dispersion according to claim 1, characterized in that the protective colloid is essentially free of diketenes.

3. Aqueous dispersions according to claim 1 or 2, characterized in that the aqueous dispersions contain less than 1% by weight, based on the aqueous dispersion, of cationic starch.

4. Aqueous dispersions according to claims 3, characterized in that the aqueous dispersions are essentially free of cationic starch.

5. Aqueous dispersions according to one of claims 1 to 4, characterized in that the polymers containing cationic vinylamine units are 1 to 100 mol% hydrolyzed homo- or copolymers of N-vinylformamide.

6. Aqueous dispersions according to one of claims 1 to 5, characterized in that the polymers containing cationic vinylamine units have an average molecular weight M w of 1,000 to 2 million.

7. Aqueous dispersions according to one of claims 1 to 6, characterized in that the content of protective colloid is 10 to 100 wt .-%, based on the reactive sizing agent.

8. Aqueous dispersions according to any one of claims 1 to 7, characterized in that C ₁₂ - to C ₂₂ alkyl ketene dimers, C ₅ - to C ^ alkyl or C ₅ - to C ^ alkenyl succinic anhydrides and / or C as reactive sizing agents ₁₂ - C ₃₆ alkyl isocyanates.

9. Aqueous dispersions according to claim 8, characterized in that the content of reactive sizes 1 to 50 wt .-%, based on the total weight of the dispersion.

10. A process for the preparation of aqueous dispersions according to any one of claims 1 to 9, characterized in that in an aqueous mixture, the reactive sizes and the cationic vinylamine units containing polymers polymers in the presence of an anionic dipsergic agent at temperatures of 20 to 100 ° C under the action of shear forces.

11. A process for the mass sizing of paper, cardboard and cardboard by adding aqueous dispersions according to any one of claims 1 to 9 to an aqueous slurry of cellulose fibers and dewatering the paper stock.

12. Use of the aqueous dispersions according to one of claims 1 to 9 as a mass sizing agent in the manufacture of paper, cardboard, cardboard and liquid cardboard.