WO2000063295A1 - Hydrogel-forming polymer mixture - Google Patents

Abstract

The invention relates to a hydrogel-forming polymer mixture containing a) a hydrogel-forming polymer I with acid rests and b) a hydrogel-forming polymer II with amino and/or imino rests. The ratio of acid rests to the sum of amino/imino rests is between 1: 9 and 9: 1. The invention also relates to the use of said mixture in absorbent hygiene articles.

Description

Hydrogel-forming polymer blend

description

The present invention relates to hydrogel-forming polymer mixtures containing

a) a hydrogel-forming polymer I with acid residues and

b) a hydrogel-forming polymer II with amino and / or imino residues,

where the ratio of the acid residues to the sum of amino / imino residues is 1: 9 to 9: 1,

as well as the use of these mixtures in absorbent hygiene articles.

The development of new hydrogel-forming polymers, so-called superabsorbers, with better absorbent properties is still of great interest, since good absorbent properties go hand in hand with high wearing comfort, particularly in the area of disposable hygiene items such as diapers or incontinence pads. In addition, better superabsorbents enable the use of smaller amounts of cellulose, which enables the production of thinner hygiene articles and is therefore of economic importance since it reduces packaging and transport costs.

Superabsorbents often have satisfactory results in terms of their absorption capacity for deionized water, but they decrease when exchanged for body fluids such as urine. This effect of the quasi "poisoning" of the super absorber is generally attributed to the salinity of the body fluids.

To minimize this effect, WO 96/15162, WO 96/15163, WO 96/17681 and WO 98/37149 propose a superabsorbent material which is composed of an anionic and a cationic superabsorbent material, the cationic superabsorbent material being polymer units which are quaternary amine functions and are due to bisallylbisalkylammonium ions.

Mixtures of anionic and cationic superabsorbent materials, the latter having quaternary amine functions, that is to say cannot be deprotonated, are included in the WO 92/20735, WO 96/15180, DE-A-19640329 and WO 98/24832. The polydiallyldimethylammonium hydroxide used here must be prepared by polymerizing the corresponding chloride and then first converted into the hydroxide form by extensive washing with sodium hydroxide solution before it can be mixed with the anionic superabsorbent material after drying.

Furthermore, the so-called "gel-blocking" effect, which is a reduced onward transport of liquid into deeper superabsorbent layers, must be prevented, so that US Pat. No. 5,599,335, US Pat. No. 5,669,894 and US Pat. No. 5,562,646 describe a test method that meets this requirement (Saline Flow Conductivity SFC) and this Describe the resulting requirement profile.

EP-A-0210756 teaches an absorbent mixture of a cation and an anion exchange material, which is a modified cellulose fiber in both cases.

The object of the present invention was to provide a new hydrogel-forming polymer mixture which has good absorption properties, good distribution properties and high mechanical stability.

Accordingly, the above polymer blends have been found.

Hydrogel-forming polymers I are water-insoluble polymers with free acid groups. Crosslinked polyacids, in particular polycarboxylic acids, which can partly be present as a salt, are preferred. Polymers I with an acid group density (meq / g)> 4, in particular> 8, especially> 12, are preferred.

Polymers I which are prepared by crosslinking polymerization or copolymerization of monoethylenically unsaturated monomers bearing acid groups are preferred. It is also possible to (co) polymerize the monoethylenically unsaturated monomers bearing acid groups without crosslinking agents and to subsequently crosslink them.

Such monomers bearing acid groups are, for example, monoethylenically unsaturated C ₃ -C ₂₅ -carboxylic acids or anhydrides such as acrylic acid, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid and fumaric acid. Also suitable are monoethylenically unsaturated sulfonic or phosphonic acids, for example vinylsulfonic acid, allylsulfonic acid, sulfoethyl acrylate, sulfoethyl methacrylate, sulfo- fopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfonic acid, 2-hydroxy-3-methacryloxypropylsulfonic acid, vinylphosphonic acid, allylphosphonic acid, styrene sulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid. The monomers can be used alone or as a mixture with one another.

Preferred monomers are acrylic acid, methacrylic acid, vinylsulfonic acid, acrylamidopropanesulfonic acid or mixtures of these acids, e.g. Mixtures of acrylic acid and methacrylic acid, mixtures of acrylic acid and acrylamidopropanesulfonic acid or mixtures of acrylic acid and vinylsulfonic acid.

To optimize properties, it can be useful to use additional monoethylenically unsaturated compounds which do not have an acid group but can be copolymerized with the monomers bearing acid groups. These include, for example, the amides and nitriles of monoethylenically unsaturated carboxylic acids, for example acrylamide, methacrylamide and N-vinylformamide, N-vinyl acetamide, N-methyl-N-vinyl acetamide, acrylonitrile and methacrylonitrile. Other suitable compounds are, for example, vinyl esters of saturated Cχ ~ to C -carboxylic acids such as vinyl formia, vinyl acetate or vinyl propionate, alkyl vinyl ether with at least 2 C atoms in the alkyl group, such as ethyl vinyl ether or butyl vinyl ether, esters of monoethylenically unsaturated C ₃ - to C ₆ -carboxylic acids , for example esters from monohydric Cχ ~ to cis alcohols and acrylic acid, methacrylic acid or maleic acid, half esters of maleic acid, for example monomethyl maleate, N-vinyl lactams such as N-vinylpyrrolidone or N-vinylcaprolactam, acrylic acid and methacrylic acid esters of alkoxylated monohydric, saturated alcohols, for example from Alcohols with 10 to 25 carbon atoms which have been reacted with 2 to 200 moles of ethylene oxide and / or propylene oxide per mole of alcohol, and also monoacrylic acid esters and monomethacrylic acid esters of polyethylene glycol or polypropylene glycol, the molar masses (M _N ) of the polyalkylene glycols, for example can be up to 2000. Other suitable monomers are styrene and alkyl-substituted styrenes such as ethylstyrene or tert. Butyl styrene.

These monomers not bearing acid groups can also be used in a mixture with other monomers, e.g. Mixtures of vinyl acetate and 2-hydroxyethyl acrylate in any

Relationship. These monomers not carrying acid groups are added to the reaction mixture in amounts between 0 and 80% by weight, preferably less than 50% by weight.

Compounds which have at least 2 ethylenically unsaturated double bonds can function as crosslinkers. Examples of compounds of this type are N, N '-methylene-bisacrylamide, poly- ethylene glycol diacrylates and polyethylene glycol dimethacrylates, which are each derived from polyethylene glycols with a molecular weight of 106 to 8500, preferably 400 to 2000, trimethylol propane triacrylate, trimethylol propane trimethacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, hexane diol acrylate, allyl diol acrylate, butane diol diacrylate, allyl diacrylate, acrylate, butane diol diol acrylate, butane diol diol acrylate, block diol acrylate from ethylene oxide and propylene oxide, double or triple esterified with acrylic acid or methacrylic acid, polyhydric alcohols, such as glycerol or pentaerythritol, triallylamine, tetraallylethylene diamine, divinylbenzene, diallyl phthalate, polyethylene glycol divinyl ether of polyethylene glycols with an average molecular weight of 126 to 4000 diol, butyl dimethyl ether and trimethylol propane , Pentaerythritol triallyl ether and / or divinylethylene urea. Water-soluble crosslinking agents are preferably used, for example N, N '-methylene-bisacrylamide, polyethylene glycol diacrylates and polyethylene glycol dimethacrylates which are derived from addition products of 2 to 400 mol of ethylene oxide to 1 mol of a diol or polyol, vinyl ethers of addition products of 2 to 400 mol Ethylene oxide on 1 mole of a diol or polyol, ethylene glycol diacrylate, ethylene glycol dimethacrylate or triacrylates and trimethacrylates of addition products of 6 to 20 moles of ethylene oxide on 1 mole of glycerol, pentaerythritol triallyl ether and / or divinyl urea.

Also suitable as crosslinkers are compounds which contain at least one polymerizable ethylenically unsaturated group and at least one further functional group. The functional group of these crosslinkers must be able to react with the functional groups, essentially the acid groups of the monomers. Suitable functional groups are, for example, hydroxyl, amino, epoxy and aziridino groups. For example, use can be made of hydroxyalkyl esters of the abovementioned monoethylenically unsaturated carboxylic acids, for example 2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and hydroxylbutyl methacrylate, dialkyldiallylammonium halide, such as dimethyldimidylchloride, such as dimethyldimidium chloride, N-vinylimidazole, l-vinyl-2-methylimidazole and N-vinylimidazolines such as N-vinylimidazoline, l-vinyl-2-methylimidazoline, l-vinyl-2-ethylimidazoline or l-vinyl-2-propylimidazoline, which are in the form of free bases, in quaternized form or as a salt can be used in the polymerization. Dialkylaminoalkyl acrylates and dialkylaminoalkyl methacrylates, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate are also suitable. The basic esters will preferably used in quaternized form or as a salt. Furthermore, glycidyl (meth) acrylate can also be used, for example. The crosslinkers are present in the reaction mixture, for example from 0.001 to 20% by weight and preferably from 0.01 to 14% by weight.

The polymerization is initiated as usual by an initiator. All initiators which form free radicals under the polymerization conditions and are usually used in the production of superabsorbers can be used as initiators for initiating the polymerization. Also one

Initiation of the polymerization by the action of electron beams on the polymerizable, aqueous mixture is possible. However, the polymerization can also be initiated in the absence of initiators of the type mentioned above by exposure to high-energy radiation in the presence of photoinitiators. All compounds which decompose into free radicals under the polymerization conditions can be used as polymerization initiators, for example peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and the so-called redox catalysts. The use of water-soluble initiators is preferred. In some cases it is advantageous to use mixtures of different polymerization initiators, for example mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate. Mixtures of hydrogen peroxide and sodium peroxodisulfate can be used in any ratio. Suitable organic peroxides are, for example, acetylacetone peroxide, methyl ethyl ketone peroxide, tert. -Butyl hydroperoxide, cumene hydroperoxide, tert-amyl perpivalate, tert. Butyl perpivalate, tert. Butyl perneohexanoate, tert. -Butylperisobutyra, tert. -Butyl-per-2-ethylhexanoate, tert. - Butyl perisononanoate, tert. -Butyl permaleate, tert. -Butyl perbenzoate, di- (2-ethylhexyl) peroxidicarbonate, dicyclohexyl peroxidicarbonate, di- (4-tert.-butylcyclohexyl) eroxidicarbonate, dimyristil-peroxy-dicarbonate, diacetyl peroxidicarbonate, allyl peresters, cumylperoxy, tert-neodecanoate. -Butylper-3, 5, 5-tri-methylhexanoate, acetylcyclo-clohexyl-sulfonyl peroxide, dilauryl peroxide, dibenzoyl peroxide and tert. -Amylperneodecanoate. Particularly suitable polymerization initiators are water-soluble azo starters, for example 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N 'dimethyl) isobutyramidine dihydrochloride, 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis [2- (2 '-imidazolin-2-yl) propane] dihydrochloride and 4,4'-azobis (4-cyanovaleric acid). The polymerization initiators mentioned are used in customary amounts, for example in amounts of 0.01 to 5, preferably 0.1 to 2.0% by weight, based on the monomers to be polymerized. Redox catalysts are also suitable as initiators. The redox catalysts contain at least one of the above-mentioned per compounds as the oxidizing component and, for example, ascorbic acid, glucose, sorbose, ammonium or alkali metal hydrogensulfite, sulfite, thiosulfate, hyposulfite, pyrosulfite or sulfide, metal salts as the reducing component , such as iron (II) ions or silver ions or sodium hydroxymethylsulfoxy- lat. Ascorbic acid or sodium sulfite is preferably used as the reducing component of the redox catalyst. Based on the amount of monomers used in the polymerization, for example 3-10 ^-6 to 1 mol% of the reducing component of the redox catalyst system and 0.001 to 5.0 mol% of the oxidizing component of the redox catalyst are used.

If the polymerisation by exposure to high energy

Triggers radiation, so-called photoinitiators are usually used as initiators. These can be, for example, so-called α-splitters, H-abstracting systems or also azides. Examples of such initiators are benzophenone derivatives such as Michler's ketone, phenanthrene derivatives, fluorene derivatives, anthraquinone derivatives, thioxanone derivatives, coumarin derivatives, benzoin ethers and their derivatives, azo compounds such as the radical formers mentioned above, substituted hexaaryl bisimidazoles or Acylphosphine oxides. Examples of azides are: 2- (N, -dimethylamino) -ethyl-4-azidocinnamate, 2- (N, -dimethylamino) -ethyl-4-azidonaphthyl ketone, 2- (N, N-dimethylamino) -ethyl -4-azidobenzoate, 5-azido-l-naphthyl-2 '- (N, N-dimethylamino) ethylsulfone, N- (4-sulfonyl azidophenyldmaleinimide, N-acetyl-4-sulfonyl azidoaniline, 4-sulfonyl azidoaniline, 4- Azidoaniline, 4-azidophenacyl bromide, p-azide-topzoic acid, 2, 6-bis (p-azidobenzylidene) cyclohexanone and

2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone. If they are used, the photoinitiators are usually used in amounts of 0.01 to 5% by weight, based on the monomers to be polymerized.

In the subsequent crosslinking, polyacids which have been prepared by the polymerization of the abovementioned monoethylenically unsaturated acids and, if appropriate, monoethylenically unsaturated comonomers and which have a molecular weight greater than 5000, preferably greater than 50,000, are reacted with compounds which have at least two groups which are reactive towards acid groups exhibit. This reaction can take place at room temperature or at elevated temperatures up to 200 ° C. The suitable functional groups have already been mentioned above, ie hydroxyl, amino, epoxy, isocyanate, ester, amido and aziridino groups. Examples of such crosslinking agents are ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, polyglycerol, propylene glycol, polypropylene glycol, block copolymers from ethylene oxide and propylene oxide, sorbitan fatty acid ester, ethoxylated sorbitan fatty acid ester, 3-trimethylol propane, pentaerythritol , 1,4-butanediol, polyvinyl alcohol, sorbitol, polyglycidyl ethers such as ethylene glycol, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol polyglycidyl ether, Diglycerinpo- lyglycidylether, polyglycerol polyglycidyl ether, Sorbitpolyglyci- dylether, pentaerythritol polyglycidyl ether, Propylenglykoldiglyci - dylether and polypropylene glycol, Polyaziridinver- compounds such as 2, 2-bishydroxymethyl butanol-tris [3- (1-aziridinyl) propionate], 1, 6-hexamethylene diethylene urea, diphenylmethane bis-4, 4 '-N, N' -diethylene urea, hydroxyepoxy compounds such as glycidol, haloepoxy compounds such as Epichlo rhydrin and α-methylene epifluorohydrin, polyisocyanates such as 2, 4-tolylene diisocyanate and hexamethylene diisocyanate, alkylene carbonates such as

1, 3-dioxolan-2-one and 4-methyl-l, 3-dioxolan-2-one, furthermore bis-oxazolines and oxazolidones, furthermore polyquaternary amines such as condensation products of dirnethylamine with epichlorohydrin, homo- and copolymers of diallyldimethylammonium chloride as well as homo- and copolymers of dimethylaminoethyl (meth) acrylate, which are optionally quaternized with, for example, methyl chloride.

Other suitable crosslinkers for postcrosslinking are polyvalent metal ions, which are able to form ionic crosslinks. Examples of such crosslinkers are magnesium, calcium, barium and aluminum ions. These crosslinkers are added, for example, as hydroxides, carbonates or bicarbonates to the aqueous polymerizable solution. Other suitable crosslinkers are multifunctional bases which are also able to form ionic crosslinks, for example polyamines or their quaternized salts. Examples of polyamines are ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine and polyethylene imines as well as polyvinyl amines with molecular weights of up to 4,000,000 each.

The crosslinking agents are added to the polyacrylic acid or the polyacrylic acid salts in amounts of 0.5 to 25% by weight, preferably 1 to 15% by weight, based on the amount of the polyacids used. The crosslinked polyacids are used in the invention

Polymer mixture preferably used unneutralized. Nevertheless, it can be advantageous to partially re-acidify the acid functions. tralize. The degree of neutralization will be essentially less than 50%, preferably less than 30%. Possible neutralizing agents are:

Alkali metal bases or ammonia or amines. Sodium hydroxide solution or potassium hydroxide solution is preferably used. However, the neutralization can also be carried out using sodium carbonate, sodium hydrogen carbonate, potassium carbonate or potassium hydrogen carbonate or other carbonates or hydrogen carbonates or ammonia. Furthermore, prim. , sec. and tert. Amines can be used.

All processes which are usually used in the production of superabsorbers, such as are used, for example, can be used as technical processes for producing these products. in chapter 3 in "Modern Superabsorbent Polymer Technology",

F.L. Buchholz and A.T. Graham, Wiley-VCH, 1998.

Polymerization in aqueous solution is preferred as so-called gel polymerization. 10 to 70% by weight aqueous solutions of the monomers and, if appropriate, a suitable graft base are polymerized in the presence of a radical initiator using the Trommsdorff-Norrish effect.

The polymerization reaction can be carried out in the temperature range between 0 and 150.degree. C., preferably between 10 and 100.degree. C., both under normal pressure and under elevated or reduced pressure. As usual, the polymerization can also be carried out in a protective gas atmosphere, preferably under nitrogen.

The quality properties of the polymers can be improved further by reheating the polymer gels for several hours in the temperature range from 50 to 130 ° C., preferably from 70 to 100 ° C.

Suitable polymers I are also graft (co) polymers of one or more hydrophilic monomers on a suitable graft base, crosslinked cellulose or starch ethers and esters containing acid groups, crosslinked carboxymethyl cellulose, or natural products with acid groups which are swellable in aqueous liquids, such as, for example Alginates and carrageenans.

Suitable graft bases can be of natural or synthetic origin. Examples are starch, cellulose or cellulose derivatives and other polysaccharides and oligosaccharides, polyvinyl alcohol, polyalkylene oxides, in particular polyethylene oxides and Polypropylene oxides, polyamines, polyamides and hydrophilic polyesters. Suitable polyalkylene oxides have, for example, the formula

X

R — O— (CH ₂ -CH-0) _n —R ²

wherein R ¹ and R ² independently of one another are hydrogen, alkyl, alkenyl or acrylic,

X is hydrogen or methyl and n is an integer from 1 to 10,000.

R ¹ and R ^{2 are} preferably hydrogen, (-C ~ C ₄ ) alkyl, (C -C ₆ ) alkenyl or phenyl.

Polymer II is to be understood as an amino radical according to the IUPAC rules, primary amino groups and not amido groups in which the NH radical is linked to a carbonyl radical. Accordingly, imino residue according to the IUPAC rules are to be understood as secondary amino groups (-NH-) and not imido groups in which the NHR residue is linked to a carbonyl residue.

Suitable hydrogel-forming polymers II are the following polymers bearing amino and / or imino residues which have been rendered water-insoluble by crosslinking. Preferred polymers are polymers, copolymers and graft copolymers of "vinylamine" or ethyleneimine, which can be modified in a polymer-analogous manner.

a) So-called polyvinylamines, i.e. polymers with the grouping -CH -CH (NH ₂ ) - as a characteristic building block, are accessible via polymer-analogous reactions. As such polymer-analogous reactions, those skilled in the art are, for example, the hydrolysis of poly-N-vinyl amides such as poly-N-vinyl formamide, poly-N-vinyl acetamide, of poly-N-vinyl imides such as poly-N-vinyl succinimide and poly-N-vinyl phthalimide and the Hofmann degradation of polyacrylamide when exposed to basic hypochlorite is known.

Polyvinylamines are preferably prepared by polymerization of N-vinylformamide and subsequent polymer-analogous reaction in accordance with DE-A-3 128 478. The molecular weight of the uncrosslinked polyvinylamine corresponds to a K value (determined according to H. Fikentscher, 5% by weight aqueous NaCl solution at 25 ° C. containing 1% by weight polymer) of 30-250. 10

The N-vinylformamide units of the polymers can be hydrolyzed by acidic, basic or enzymatic hydrolysis to give the corresponding polymers containing vinylamine units. If you e.g. completely hydrolyzed a homopolymer of N-vinylformamide, polyvinylamine is obtained. Basic hydrolysis is particularly preferred. In this way degrees of hydrolysis of e.g. 5 - 95% available. Particularly preferred are products with a degree of hydrolysis of 70 to 100 and very particularly completely hydrolyzed products, i.e. maximum 100%, usually 95%. The degree of hydrolysis is determined, for example, by enzymatic determination of the formate or by polyelectrolyte titration of the available amine functions with potassium polyvinyl sulfate solution.

Crosslinked polyvinylamines are preferably used as Polymers II which have previously been desalted. Desalted here means that the salt content of low molecular weight salts (molecular weight <500) is 8% by weight, based on the polymer. Desalination is carried out, for example, by means of a dialysis or ultrafiltration process with a membrane with a 3000 D exclusion limit. The degree of desalination can be checked using gel permeation chromatography (GPC). Desalination is advantageously carried out after the polymer-analogous reaction and before the crosslinking reaction.

The desalted polymer solutions II are usually used in aqueous solution for crosslinking. The polymer content of an aqueous solution is usually 2 to 50% by weight. In addition, it is possible by the addition of polar aprotic Lö ^¬ sungsmitteln such as dimethyl sulfoxide or N-methylpyrrolidone to crosslink even more concentrated polymer solutions.

As mentioned above, preference is given to polymers II which are obtained by crosslinking polyvinylamine with a K value of 30-250, preferably 50-230, in particular 70-200. Since the crosslinking slows down and possibly runs incompletely in the case of the high molecular weight polyvinylamines, it is particularly preferred to crosslink polyvinylamines which, in the uncrosslinked state, have a K value of 70-180.

As further hydrogel-forming polymers II, copolymers of “vinylamine” are suitable, that is copolymers of, for example, vinylformamide and comonomers, which are converted into formal copolymers of vinylamine by the polymer-analogous reactions described above. In principle, all monomers copolymerizable with vinylformamide are suitable as comonomers. The following monounsaturated monomers may be mentioned by way of example:

Acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, styrene, ethylene, propylene, N-vinyl pyrrolidone, N-vinyl caprolactam, N-vinyl imidazole, sulfone- or phosphonate group-containing monomers, vinyl glycol, acrylamido (methacrylamido) alkylene- trialkylammonium salt, diallyl-dialkylammonium salts, (Cι ~ C) -alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, t-butyl vinyl ether, N-substituted alkyl (meth) acrylamides substituted by a (Cχ-C ₄ ) -Alkyl group such as N-methyl acrylamide, N-isopropylacrylamide and N, N-dimethylacrylamide and (-C-C ₀ ) -alkyl (meth) acrylic acid ester such as methyl acrylate, ethyl methacrylate, propyl acrylate, butyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxyl, propyl acrylate Hydroxypropyl methacrylate, hydroxibutyl acrylate, hydroxibutyl methacrylate, 2-methylbutyl acrylate, 3-methylbutyl acrylate, 3-pentyl acrylate, neopentyl acrylate, 2-methylpentyl acrylate, hexyl acrylate, C yclohexyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, heptyl acrylate, benzyl acrylate, tolylacrylate, octyl acrylate, 2-octyl acrylate, nonylacrylate and octyl methacrylate.

Specific copolymers should be mentioned in detail. For example, DE-A-3 534 273 copolymers of N-vinylformamide with vinyl acetate, vinyl propionate, (Cι ~ C) alkyl vinyl ether, methacrylic acid and acrylic acid esters, acrylonitrile and acrylamide and their homologues and vinyl pyrrolidone.

The concentration of the N-vinylformamide can be 10-95 mol%, that of the comonomers 5-90 mol%.

Graft polymers of alkylene oxide units and N-vinylformamide according to DE-A-1 951 5943, which were crosslinked after the hydrolysis, are also suitable as polymers II. Such graft polymers can be prepared by radical polymerization of N-vinylformamide in the presence of, for example, polyethylene glycols and subsequent basic saponification.

Further advantageous graft bases are polyvinyl acetate and / or polyvinyl alcohol. According to DE-A-19 526 626, N-vinylformamide can be grafted onto these polymers by radical polymerization and the polymer thus obtained is hydrolyzed, optionally desalted and then crosslinked to give polymer II. Copolymers of vinyl acetate, acrylic acid, methacrylic acid, acrylamide and acrylonitrile are also suitable graft bases for N-vinylformamide. Furthermore, according to DE-A-4 127 733, mono-, oligo- and polysaccharides, which have optionally been oxidatively, enzymatically or hydrolytically degraded, are advantageous graft bases for N-vinylformamide, the proportion by weight of which is 20 to 95% based on the total amount of monomer + graft base . These graft polymers are then converted into the free amines by hydrolysis, optionally desalted and finally crosslinked to give polymers II.

The graft polymers are preferably formed with N-vinylformamide as the only monomer. However, it is possible to replace up to 50% by weight of the N-vinylformamide with the above-mentioned comonomers of the N-vinylformamide.

The polyvinylamines, their copolymers and graft copolymers can also be modified by further polymer-analogous reactions. These reactions are diverse and can be found in any textbook on organic chemistry such as "Advanced Organic Chemistry" by Jerry March, 3rd edition, John Willey & Sons 1985.

Some of the many possible reactions with primary amines are to be mentioned here as representative. In the presence of

Formic acid or formic acid orthoesters react vicinal amino groups of polyvinylamine to six-membered cyclic amidines, as described, for example, in US Pat. No. 5,401,808. It may well be that some of the amino groups have reacted with vicinal formamide groups to form cyclic amidine structures. Likewise, according to DE-A 4 328 975 copolymers of acrylonitrile, methacrylonitrile or their homologues, as well as acrylic and methacrylic esters with N-vinylformamide in intramolecular condensation reactions during or after hydrolysis of the formamide groups to the corresponding amino groups, with adjacent nitrile or Carboxylic ester groups react to the corresponding 2-amino-l-imidazoline or the corresponding γ-lactam structures. The proportion of amino groups reacted in a polymer-analogous manner can be up to 50 mol%.

In addition to these intramolecular, polymer-analogous reactions of polyvinylamines, a large number of other such reactions are possible. These include amidation, alkylation, sulfonamide formation, urea formation, thiourea formation, carbamate formation, acylation with acids, lactones, acid anhydrides and acid chlorides, thiocarbation, carboximethylation, phosphonomethylation, Michael addition to name just a few. So forth Polyvinylamine derivatives are also suitable for the production of crosslinked polymers II. The polymer-analogous reactions are preferably carried out before the crosslinking of the polyvinylamines, the copolymers and the graft copolymers of the "vinylamine". The proportion of the amino groups reacted in a polymer-analogous manner is up to 50%, preferably 10 to 30 mol%, of the amino groups of the polymer used. The polymers obtained by subsequent crosslinking are preferred, in particular those which have been desalted before the crosslinking step.

b) Also included are polyethyleneimines, polyamidoamines grafted with ethyleneimine or polyamines grafted with ethyleneimine, and reaction products of these polymer classes with α, β-unsaturated carboxylic acids, their esters or reaction products with the reaction products of formaldehyde with HCN or formaldehyde

Alkali cyanides (Strecker reaction) and, if appropriate, subsequent hydrolysis to give the corresponding carboxylic acids.

Another class of amino groups, preferably polymers containing ethyleneimine units, is known from WO-A-94/12560. These are water-soluble, crosslinked, partially amidated polyethyleneimines, which are obtainable from

Reaction of polyethyleneimines with monobasic carboxylic acids or their esters, anhydrides, acid chlorides or acid amides with the formation of amides and

Reaction of the amidated polyethyleneimines with at least two functional crosslinkers.

The molar masses of the polyethyleneimines in question can be up to 5 million and are preferably in the range from 1000 to 1 million. The polyethyleneimines are partially identified with monobasic carboxylic acids, so that, for example, 0.1 to 90, preferably 1 to 50% of the amidatable nitrogen atoms in the polyethyleneimines is present as an amide group. Suitable crosslinkers containing at least two functional groups are mentioned above. Halogen-free crosslinkers are preferably used.

In the reaction of amino group-containing compounds with crosslinking agents, 0.1 to 50, preferably 1 to 5 parts by weight of at least one crosslinking agent is used, for example, for 1 part by weight of a compound containing amino groups.

Other addition products containing amino groups which are used as a component in superabsorbers after crosslinking are polyethyleneimines and quaternized polyethyleneimines. The Polyethyleneimines and the quaternized polyethyleneimines can optionally be reacted with a crosslinker containing at least two functional groups. The quaternization of the polyethyleneimines can be carried out, for example, with alkyl halides such as methyl chloride, ethyl chloride, hexyl chloride, benzyl chloride or lauryl chloride and with, for example, dimethyl sulfate. These reaction products may have to be desalinated. Other suitable polymers containing amino groups are polyethyleneimines modified by the Strecker reaction, for example the reaction products of polyethyleneimines with formaldehyde and sodium cyanide with hydrolysis of the nitriles formed to give the corresponding carboxylic acids. These products can optionally be reacted with a crosslinker containing at least two functional groups or can crosslink with themselves with the formation of amides and the escape of water.

Also suitable are alkoxylated polyethyleneimines, which can be obtained, for example, by reacting polyethyleneimine with ethylene oxide and / or propylene oxide. The alkoxylated polyethyleneimines are reacted with a crosslinker containing at least two functional groups and are thus rendered water-insoluble. The alkoxylated polyethyleneimines contain 0.1 to 100, preferably 1-3 alkylene oxide units per NH group. The molecular weight of the polyethyleneimines can be up to two million. Preferably, the alkoxylation uses polyethyleneimines with molecular weights of 1,000 to 50,000. Other suitable water-soluble amino group-containing polymers are reaction products of polyethyleneimines with diketenes, e.g. of polyethyleneimines with a molecular weight of 1,000 to 50,000 with distearyl diketene, which are then crosslinked.

Crosslinked polyethyleneimines are described, for example, in EP 0895 521.

The polyethyleneimine is produced in a conventional manner by cationic polymerization of ethyleneimine in the presence of polymerization catalysts such as acids, Lewis acids, acidic metal salts or alkylating reagents. Polyethyleneimines with a molecular weight of 1,000 to 5,000,000 (determined, for example, by static light scattering) are preferably crosslinked to give polymers II.

Crosslinkers for the preparation of the hydrogel-forming polymers II are bifunctional or polyfunctional, that is to say they have two or more active groups which correspond to the amino or imino residues of the

Polymers can react. In addition to the low molecular weight crosslinkers polymers and copolymers, which are preferably water-soluble, can also be used as crosslinkers.

Suitable bifunctional or polyfunctional crosslinkers are, for example

(1) Di- and polyglycidyl compounds

(2) Di- and polyhalogen compounds

(3) Compounds with two or more isocyanate groups, which can be blocked (4) Polyaziridines

(5) carbonic acid derivatives

(6) Compounds with two or more activated double bonds that can undergo Michael addition

(7) Di- and polycarboxylic acids and their acid derivatives (8) monoethylenically unsaturated carboxylic acids, their esters, amides and anhydrides (9) di- and polyaldehydes and di- and polyketones.

Preferred crosslinkers (1) are, for example, the bischlorohydrin ethers of polyalkylene glycols described in US Pat. No. 4,144,123. Phosphoric acid diglycidyl ether and ethylene glycol diglycidyl ether may also be mentioned.

Further crosslinkers are the reaction products of at least trihydric alcohols with epichlorohydrin to reaction products which have at least two chlorohydrin units, e.g. the polyhydric alcohols used are glycerol, ethoxylated or propoxylated glycerols, polyglycerols having 2 to 15 glycerol units in the molecule and, if appropriate, ethoxylated and / or propoxylated polyglycerols. Crosslinkers of this type are known, for example, from DE-A-2 916 356.

Suitable crosslinkers (2) are α, ω- or vicinal dichloroalkanes, for example 1,2 dichloroethane, 1,2 dichloropropane, 1,3-dichlorobutane and 1, 6-dichlorohexane.

Furthermore, EP-A-0 025 515 discloses α, ω-dichloropolyalkylene glycols which preferably have 1 to 100, in particular 1 to 100, ethylene oxide units as crosslinkers.

Also suitable are crosslinkers (3) which contain blocked isocyanate groups, for example trimethylhexamethylene diisocyanate blocked with 2, 2, 6, 6-tetramethylpiperidin-4-one. Such crosslinkers are known, cf. for example from DE-A-4 028 285. Crosslinkers (4) based on polyethers or substituted hydrocarbons, for example 1,6-bis-N-aziridinomethane, cf. US Pat. No. 3,977,923. This crosslinker class also includes at least two reaction products of dicarboxylic acid esters with ethyleneimine and mixtures of the crosslinkers mentioned, which contain aziridino groups.

Halogen-free crosslinkers of group (4) are reaction products which are prepared by reacting dicarboxylic acid esters which are completely esterified with monohydric alcohols having 1 to 5 carbon atoms with ethyleneimine. Suitable dicarboxylic acid esters are, for example, dimethyl oxalate, diethyl oxalate, dimethyl succinate, diethyl succinate, dimethyl adipate, diethyl adipate and dimethyl glutarate. For example, the reaction of diethyl oxalate with ethyleneimine gives bis - [ß- (1-aziridino) ethyl] oxalic acid amide. The dicarboxylic acid esters are reacted with ethyleneimine, for example in a molar ratio of 1 to at least 4. Reactive groups of these crosslinkers are the terminal aziridine groups. These crosslinkers can be characterized, for example, using the formula:

H

where n = 0 to 22.

Examples of crosslinkers (5) include ethylene carbonate, propylene carbonate, urea, thiourea, guanidine, dicyandiamide or 2-oxazolidinone and their derivatives. From this group of monomers, propylene carbonate, urea and guanidine are preferably used.

Crosslinkers (6) are reaction products of polyether diamines, alkylenediamines, polyalkylene polyamines, alkylene glycols, polyalkylene glycols or their mixtures with monoethylenically unsaturated carboxylic acids, esters, amides or anhydrides of monoethylenically unsaturated carboxylic acids, the reaction products being at least two ethylenically unsaturated carboxylic acid, carboxylamides, carboxylamides, or unsubstituted carboxamides Have gruppenster groups as functional groups, as well as methylene bisacrylamide and divinyl sulfone. Crosslinkers (6) are, for example, reaction products of polyether diamines with preferably 2 to 50 alkylene oxide units, alkylenediamines such as ethylenediamine, propylenediamine, 1,4-diamino-butane and 1,6-diaminohexane, polyalkylene polyamines with molecular weights <5000, for example diethylene triamine, triethylene tetramine, dipropylenetriamine Tripropylenetetramine, dihexamethylenetriamine and aminopropylethylenediamine, alkylene glycols, polyalkylene glycols or mixtures thereof

monoethylenically unsaturated carboxylic acids,

Esters of monoethylenically unsaturated carboxylic acids,

Amides of monoethylenically unsaturated carboxylic acids and

Anhydrides of monoethylenically unsaturated carboxylic acids.

These reaction products and their preparation are described in EP-A-873 371 and are expressly mentioned as crosslinkers.

Crosslinking agents which are particularly preferred are the reaction products mentioned here of maleic anhydride with α, ω-polyether diamines having a molecular weight of 400 to 5000, the reaction products of polyethyleneimines having a molecular weight of 129 to 50,000 with maleic anhydride and the reaction products of ethylenediamine or triethylenetetramine with maleic anhydride Molar ratio of 1: at least 2.

The compounds of the formula are preferably used as crosslinker (6)

in which X, Y, Z = 0, NH

and Y additionally CH

m, n = 0

p, q = 0-45000

mean, which are obtainable by reacting polyether diamines, ethylenediamine or polyalkylene polyamines with maleic anhydride.

Further halogen-free crosslinkers of group (7) are at least dibasic saturated carboxylic acids such as dicarboxylic acids and the salts, diesters and dia ide derived therefrom. These compounds can, for example, using the formula

X-CO- (CH ₂ ) _n -CO-X

in which X = OH, OR ¹ , N (R ² ) ₂

R1 = CI to C ₂₂ alkyl,

R ² = H, Cχ-C ₂₂ alkyl and

n = 0 to 22

be characterized. In addition to the dicarboxylic acids of the abovementioned formula, monoethylenically unsaturated dicarboxylic acids such as maleic acid or itaconic acid are suitable, for example. The esters of the dicarboxylic acids in question are preferably derived from alcohols having 1 to 4 carbon atoms. Suitable dicarboxylic acid esters are, for example Oxalsäuredimethyl - ester, diethyl oxalate, Oxalsäurediisopropylester, succinate, Bernsteinsäuredieethylester, diisopropyl succinate, Bernsteinsäuredi-n-propyl succinate, dimethyl adipate, adipic acid diethyl ester and adipate or at least 2 Estergruppen containing Michael addition products of polyetherdiamines, polyalkylenepolyamines, or ethylene diamine, and esters of Acrylic acid or methacrylic acid, each with monohydric alcohols containing 1 to 4 carbon atoms. Suitable esters of ethylenically unsaturated dicarboxylic acids are, for example, dimethyl maleate, diethyl maleate, diisopropyl maleate, dimethyl itaconate and diisopropyl itaconate. Substituted dicarboxylic acids and their esters such as tartaric acid (D, L form and as a racemate) and tartaric acid esters such as tartaric acid dimethyl ester and tartaric acid diethyl ester are also suitable.

Suitable dicarboxylic anhydrides are, for example, maleic anhydride, itaconic anhydride and succinic anhydride. Also suitable as crosslinkers (7) are dimethyl maleate, diethyl maleate and maleic acid. The crosslinking of compounds containing amino groups with the above-mentioned crosslinkers takes place with the formation of amide groups or in the case of amides such as adipic acid diamide by transamidation. Maleic acid esters, monoethylenically unsaturated dicarboxylic acids and their anhydrides can bring about crosslinking both by forming carboxamide groups and by adding NH groups to the component to be crosslinked (for example polyamidoamines) in the manner of a Michael addition.

The at least dibasic saturated carboxylic acids of crosslinker class (7) include, for example, tri- and tetracarboxylic acids such as citric acid, propane tricarboxylic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, butanetetracarboxylic acid and diethylenetriaminepentaacetic acid. The crosslinkers of group (7) also include the salts, esters, amides and anhydrides derived from the aforementioned carboxylic acids, e.g. Tartaric acid dimethyl ester, tartaric acid diethyl ester, adipic acid dimethyl ester, adipic acid diethyl ester into consideration.

Suitable crosslinkers of group (7) are also polycarbonic acids which can be obtained by polymerizing monoethylenically unsaturated carboxylic acids, anhydrides, esters or amides. Examples of mono-unsaturated carboxylic acids include Acrylic acid, methacrylic acid, fumaric acid, maleic acid and / or itaconic acid. Suitable crosslinkers are e.g. Polyacrylic acids, copolymers of acrylic acid and methacrylic acid or copolymers of acrylic acid and maleic acid. Examples of its comonomers are its vinyl ethers, vinyl formate, vinyl acetate and vinyl lactam.

Further suitable crosslinkers (7) are produced, for example, by free-radical polymerization of anhydrides such as maleic anhydride in an inert solvent such as toluene, xylene, ethylbenzene, isopropylbenzene or solvent mixtures. In addition to the homopolymers, copolymers of maleic anhydride are suitable, for example copolymers of acrylic acid and maleic anhydride or copolymers of maleic anhydride and a C to C ₃₀ olefin.

Preferred crosslinkers (7) are, for example, copolymers of maleic anhydride and isobutene or copolymers of maleic anhydride and diisobutene. The copolymers containing anhydride groups can optionally be modified by reaction with C 1 -C ₂₀ alcohols or ammonia or amines and can be used in this form as crosslinking agents.

Preferred polymeric crosslinkers (7) are, for example, copolymers of acrylamide and acrylic esters, such as, for example, hydroxyethyl acrylate or methyl acrylate, the molar ratio of acrylamide and acrylic esters can vary from 90:10 to 10:90. In addition to these copolymers, terpolymers can also be used, it being possible, for example, to use combinations of acrylamide, methacrylamide, acrylic esters or methacrylic esters.

The molecular weight M _{w of} the homopolymers and copolymers is, for example, up to 10,000, preferably 500 to 5000. Polymers of the type mentioned above are described, for example, in EP-A-0 276 464, US-A-3 810 834, GB-A-1 411 063 and US-A-4 818 795. The at least dibasic saturated carboxylic acids and the polycarboxylic acids can also be used as crosslinking agents in the form of the alkali metal or ammonium salts. The sodium salts are preferably used. The polycarboxylic acids can be partially, for example 10 to 50 mol%, or completely neutralized.

Suitable halogen-free crosslinkers of group (8) are, for example, monoethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid and the amides, esters and anhydrides derived therefrom. The esters can be derived from alcohols with 1 to 22, preferably 1 to 18, carbon atoms. The amides are preferably unsubstituted, but can carry a C ₁ -C ₂ -alkyl radical as a substituent.

Crosslinkers (8) which are preferably used are acrylic acid, methyl acrylate, ethyl acrylate, acrylamide and methacrylamide.

Suitable halogen-free crosslinkers of group (9) are e.g. Dialdehydes or their semi- or acetals as precursors, such as, for example, glyoxal, methylglyoxal, malondialdehyde, succindialaldehyde, maleic and fumaric acid dialdehyde, tartaric dialdehyde, adipindialdehyde, 2 -oxi -adipindialdehyde, furan-2, 5 -dipropionalde Formyl-2,3-dihydropyran, glutardialdehyde, pimelic acid aldehyde and aromatic dialdehydes such as, for example, terephthalaldehyde, o-phthalaldehyde, pyridine-2, 6 -dialdehyde or phenylglyoxal. However, homo- or copolymers of acrolein of methacrolein with molar masses from 114 to approximately 10,000 can also be used. In principle, all water-soluble comonomers can be used, such as, for example, acrylamide, vinyl acetate and acrylic acid. Aldehyde starches are also suitable as crosslinkers.

Suitable halogen-free crosslinkers of group (9) are, for example, diketones or the corresponding half or ketals as precursors such as, for example, β-diketones such as acetylacetone or cycloalkane-1, n-dione such as, for example, cyclopentane-1,3-dione and cyclohexane-1 , 4-dione. However, homo- or copolymers of methyl vinyl ketone with molecular weights from 140 to about 15,000 can also be used. In principle, all water- soluble monomers such as acrylamide, vinyl acetate and acrylic acid are used.

It is of course also possible to use mixtures of two or more crosslinkers.

For the production of the superabsorbers according to the invention, preference is given to those which are free from organically bound halogen. Halogen-free crosslinking agents are therefore preferably used for the production of crosslinked polymers II, which are each insoluble in water.

The crosslinking agents described above can be used either alone or in a mixture in the reaction with water-soluble polymers containing amino groups or polyalkylene polyamines. In all cases, the crosslinking reaction is carried out to such an extent that the resulting products are no longer water-soluble but are still water-swellable. The crosslinking reaction takes place by heating the reaction components at temperatures from room temperature to 220, preferably at temperatures from

50-180 ° C. If the crosslinking reaction is carried out in an aqueous medium at temperatures above 100 ° C., it is advantageous to distill off the condensate formed (water, lower alcohols, ammonia, amines) together with the dilution water present until the reaction mixture has solidified. The polymer film is then comminuted and, if appropriate, ground with cooling using dry ice.

Polymers II are also preferred, to which no crosslinking agents have been added, but which are based on their comonomers

Are capable of self-networking. Such copolymers of vinylformamide are thermally crosslinked after their hydrolysis.

Comonomers suitable for self-crosslinking are acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters and their homologues, as well as acrylamide and acrylonitrile.

Copolymers based on acrylic or methacrylic acid esters or their homologs are particularly suitable for self-crosslinking, but also those based on acrylic or methacrylic acid or their homologs. The proportion of N-vinylformamide is usually between 50 and 99 mol%, that of the comonomers between 1 and 50 mol%. A fraction of 5-15 mol% as a comonomer fraction and 85-95 mol% as an N-vinylformamide fraction is particularly advantageous, the sum of the monomer fractions always being 100 mol%. Such copolymers are initially practical under basic conditions completely saponified, optionally desalted and then crosslinked at temperatures of 80-220, preferably 120-180 ° C. If appropriate, the crosslinking of such copolymers can be accelerated by further addition of polyvinylamines or polyethyleneimines.

However, thermal self-crosslinking can also be observed with polyvinylamine. This can be explained by the remaining formamide groups, which are also present after the hydrolysis, and by condensation with the escape of ammonia, secondary amines being formed. The ratio of the formamide groups to the amino groups can be 30/70 to 0/100, and is preferably 15/85 to 5/95. The self-crosslinking of the polyvinylamine is carried out in aqueous solution at temperatures from 100 to 200 ° C., preferably 150 to 180 ° C. In a preferred embodiment, the polyvinylamine to be crosslinked is applied in thin layers. Polyvinylamine with a K value of 70-200, particularly preferably 100-150, is preferably itself crosslinked, since this leads to hydrogel-forming polymers with advantageous properties.

The ratios in which the two hydrogel-forming polymers I and II are mixed with one another depend, in addition to other influencing variables, primarily on the density of the acid or amine groups (val / g) and the acid or base strengths. Mixing ratios can vary in a range from 20: 1 to 1:20 (weight). Mixing ratios between 10: 1 and 1:10 are preferred, particularly preferably between 7: 3 and 3: 7.

Basically, the following options are available for producing the mixture:

a) mixing the separately prepared powders,

b) mixing the water-containing gels,

c) mixing a water-containing gel with a powder,

d) adding powders or gels of one component to the reaction mixture for the production of the other component,

e) Targeted structure of a shell-shaped particle, in which the core is one component and the shell is the other component. a) All commercially available aggregates for mixing powders are suitable for mixing the separately prepared powders. The particle size of the particles to be mixed is between 10 and 2000 μm, preferably between 100 and 850 μm. It is possible to mix the two components of the same as well as different particle sizes. The use of different particle sizes in the two components can be advantageous in that differences in the uptake rate or the ion exchange rate of the two components can be coordinated with one another. It can also be advantageous to use one component in relatively coarse particles and the other in very fine particles, so that the fine-particle component is agglomerated on the surface of the coarser-particle component. If necessary, this process can be supported by adding agglomeration aids such as polyethylene glycols, water and / or polyols. Another possibility is to use very finely divided powders of both components and to agglomerate them with the addition of agglomeration aids as listed above to form agglomerates with a size between 100 μm and 1500 μm. It can also be advantageous to combine this agglomeration with a surface postcrosslinking in such a way that the postcrosslinking also brings about the agglomeration. The advantage of agglomeration (regardless of which variant) is to be seen in the fact that particles are formed in this way which contain both components together, so that when these mixtures are used in, for example, hygiene articles, no separation of the two components can occur. This effect is particularly pronounced when mixtures with very different particle sizes of the two components are used. The separation of both components means that long diffusion paths have to be overcome in the ion exchange process, which can lead to locally strongly acidic or basic pH values. This behavior is not acceptable for use in hygiene articles. Agglomeration also has the advantage that high absorption speeds can be achieved without having to use very finely divided powders which are undesirable because of their dust generation.

b) Another way of avoiding the problem of component separation described above is to mix the aqueous gels intimately and then to dry, mill and, if necessary, sieve them. Particles are obtained which contain both components firmly bonded to one another, so that a separation of the two components is not possible. It is to be expected that Build strong ionic interactions in the boundary layer of the two gel components and thus firmly connect the basic and acidic components to one another (see DE-A-19640329). The formation of a classic polyelectrolyte complex is not to be expected, since the two polyelectrolytes are each integrated in a separate network. Since both components are produced as aqueous gels, it is advantageous to use a mixture of these gels. However, it is also possible to use gels obtained from water-dried products by swelling with water. Furthermore, it may also be advantageous to partially dry the gels obtained in the preparation of the components before they are mixed. The mixing itself can be done with different equipment, such as meat grinders, kneaders, extruders, planetary roller extruders or mixers. The equipment used must ensure homogeneous, fine-particle mixing of the two components without damaging the network structure of the gels due to excessive shear. The water content of the mixed gels is between 5 and 99.8% by weight, preferably between 60 and 99% by weight. The water content of the two mixed

Gels can be the same or different. Another advantage of this variant is the fact that it dries faster, is easier to grind, in addition, no separate drying steps are required and the gel mixtures obtained have a higher gel strength and thus easier handling.

c) Another possibility is to mix the gel of one component with the powder of the other component. The procedure and the equipment used are the same as in case b). It is to be expected that in this case different structures will be obtained within a particle than if gels are mixed with one another. In the latter case, the particles will have a structure in which the components are of comparable size

Domains side by side. The size ratio of the domains is decisively determined by the mixing ratio and the solids content of the gels used and the intensity of the mixing. In the first case, the powdered component will have an island structure in a matrix of the component used in gel form. Depending on the desired range of properties, it can be advantageous to implement one or the other structure.

d) Another option for obtaining immiscible products is the addition of powders or gels of one component to the reaction mixture of the other component. For example, the addition of polymer I, for example polyacrylic acid, as a powder or gel to the polyvinylamine solution and subsequent crosslinking of the polyvinylamines leads to mixtures with advantageous properties. This crosslinking can take place by adding a crosslinker or thermally as self-crosslinking.

Likewise, by adding crosslinked polyvinylamine as a powder or gel to polymer I, e.g. Polyacrylic acid and subsequent crosslinking mixtures with advantageous properties. It is important to ensure that there are no undesired reactions. For example, when adding crosslinked polyvinylamine to a reaction mixture of acrylic acid crosslinking agent and initiator, a Michael addition between the primary amino groups of the gel and the acrylic acid immediately begins. Provided that no undesired reactions can occur, it is possible to add the powder or a gel to the reaction mixture of the other component at any time during the course of the reaction. With this variant, it can be expected that products are obtained whose boundary layer between the components has a different structure than in the case of

Gel or powder mixtures. One of the two components here is at least partially still uncrosslinked, or even as a monomer mixture. As a result, more orderly structures with stronger interactions up to polyelectrolyte complexes can form in the boundary layer and it is to be expected that the boundary layer will be significantly thicker than in the previous variants. This effect should increase the stability of the gel and also influence the range of properties that can be achieved in terms of surface post-crosslinking.

Another possibility is the production of a core-shell structure. Particles of one component are coated with a reaction mixture for producing the second component, for example by spraying. After or during the reaction, the core-shell product obtained is dried. To achieve certain layer thicknesses, it may be necessary to repeat the coating several times. On the other hand, it is also conceivable to build up multilayer particles with alternating layers of the two components using such a method. Process control in a fluidized bed is particularly suitable for the construction of simple, but in particular complex, layer structures. The main advantage of such a procedure is that defined structures can be produced with uniform and specifically adjustable layer thicknesses. The hydrogel-forming polymers (polymer I, polymer II or mixtures of polymers I and II) can be dried by various methods known to the person skilled in the art. Examples of suitable drying processes are thermal convection drying such as tray, chamber, channel, flat track, plate, rotating drum, trickle shaft, sieve belt, current, fluidized bed, fluidized bed, paddle and ball bed drying, thermal Contact drying such as heating plate, roller, belt, screen drum, screw, wobble and contact disk drying, radiation drying such as infrared drying, dielectric drying such as microwave drying, and freeze drying. In order to avoid undesired decomposition and crosslinking reactions, it can be advantageous to carry out the drying under reduced pressure, under a protective gas atmosphere and / or under gentle thermal conditions in which the product temperature does not exceed 120 ° C., preferably 100 ° C. Particularly suitable drying methods are (vacuum) belt drying and paddle drying.

The dried hydrogel-forming polymers are optionally comminuted and then ground by methods known to those skilled in the art, for example with the aid of a roller mill or a hammer mill. In the subsequent sieving, the particle size distribution is set, which is generally between 100 and 1000 μm, preferably between 120 and 850 μm. Particles that are too coarse can be subjected to grinding again, particles that are too fine can be returned to the production process.

It may also make sense to mix the described mixtures with superabsorbers already on the market, i.e. add acidic or basic crosslinked polymers whose acidic or basic groups are neutralized to at least 50%. The proportion of these commercially available superabsorbers should be less than 50%, preferably less than 25%.

In addition, the polymers I and II can be post-crosslinked in a known manner in an aqueous gel phase or post-crosslinked as dried, ground and sieved polymer particles.

In a preferred embodiment of the invention, the absorption properties of the mixtures of polymers I and polymers II thus obtained are further improved by a subsequent surface postcrosslinking. An exclusive crosslinking of the polymers I, an exclusive crosslinking of the polymers II or a crosslinking of a homogeneous mixture of both types of polymer can take place. For this purpose, connections with the functional groups of the polymers can react with crosslinking, preferably applied in the form of a water-containing solution to the surface of the hydrogel particles. The water-containing solution can contain water-miscible organic solvents. Suitable solvents are alcohols such as methanol, ethanol, i-propanol or acetone.

Suitable post-crosslinking agents are, for example

Di- or polyglycidyl compounds such as phosphonic acid diglycidyl ester or ethylene glycol diglycidyl ether, bischlorohydrin ether of polyalkylene glycols,

Glycidol and epichlorohydrin,

Alkoxysily1 compounds,

Polyaziridines, compounds containing aziridine units based on polyethers or substituted hydrocarbons, for example bis-N-aziridinomethane,

Polyamines or polyamidoamines and their reaction products with epichlorohydrin,

- Polyols such as ethylene glycol, 1, 2-propanediol, 1, 4-butanediol, glycerol, methyltriglycol, polyethylene glycols with an average molecular weight M _w of 200-10000, di- and polyglycerol, pentaerythritol, sorbitol, the oxyethylates of these polyols and their esters Carboxylic acids or carbonic acid such as ethylene carbonate or propylene carbonate,

Carbonic acid derivatives such as urea, thiourea, guanidine, dicyandiamide, 2-oxazolidinone and its derivatives, bisoxazoline, polyoxazolines, di- and polyisocyanates,

Di- or polyaldehydes such as glyoxal, succinic aldehyde or aldehyde starch,

Di- or polyketones

Compounds with two or more activated double bonds which can undergo Michael addition, such as, for example, divinyl sulfone, methylene bisacrylamide or ethylene glycol dimethacrylate, Di- and polycarboxylic acids and their anhydrides, esters, acid chlorides and nitriles such as oxalic acid, glutaric acid, adipic acid, maleic anhydride, tartronic acid, malic acid, tartaric acid or citric acid,

Di- and poly-N-methylol compounds such as, for example, methylenebis (N-methylol-methacrylamide) or melamine-formaldehyde resins,

- Di- and polyhalogen compounds such as α, ra-dichloropolyalkylene glycols, α, cj- or vicinal dichloroalkanes e.g. 1,2-dichloroethane, 1, 2-dichloropropane, 1, 3-dichlorobutane or 1.6 dichlorohexane,

Compounds with two or more blocked isocyanate groups, such as, for example, trimethylhexamethylene diisocyanate, blocked with 2, 2, 6, 6-tetramethyl-piperidinone-4,

monoethylenically unsaturated carboxylic acids, such as (meth) acrylic acid or crotonic acid, and their esters, amides, and anhydrides.

If necessary, acidic catalysts such as p-toluenesulfonic acid, phosphoric acid, boric acid or ammonium dihydrogen phosphate can be added.

Particularly suitable postcrosslinking agents are di- or polyglycidyl cidylverbindungen such as ethylene glycol diglycidyl ether, the reaction products of polyamidoamines with epichlorohydrin and which can react with both amino and carboxyl groups under Ver ^¬ networking 2-oxazoline lidinon.

Carried out the application of the cross-linking agent preferably on ^¬ spraying a solution of the crosslinker in reaction mixers or mixing and drying systems. Suitable known in the art mixing apparatus for spraying of the crosslinker solution to the poly ^¬ mer particles are, for example, Patterson-Kelly mixer, DRAIS turbulence mixers, Lödige mixers, NARA-blade mixers, screw mixers, pan mixers, fluidized bed dryer, Schugi mixer (Flexo -Mix) or PROCESSALL. Kitchen mixers such as a WARING blender are suitable for crosslinking small quantities on a laboratory scale. After spraying on the crosslinking agent solution, a temperature treatment step can follow, preferably in a downstream dryer, at a temperature between 80 and 230 ° C, preferably 80-190 ° C, and particularly preferably between 100 and 160 ° C, over a period of 5 minutes up to 6 hours, preferably 10 minutes to 2 hours and particularly preferably 10 minutes grooves up to 1 hour, whereby both fission products and solvent components can be removed. However, drying can also take place in the mixer itself, by heating the jacket or by blowing in a preheated carrier gas.

If there are particles which have structures with mutually adjacent domains or regions of polymers I and polymers II, these domains or region boundaries can also be crosslinked by thermal treatment without the addition of a crosslinking agent. The water content of the particles before this temperature treatment is preferably 0 to 50% by weight, particularly preferably 1 to 30% by weight and most preferably 2 to 20% by weight. The temperature in this annealing step is between 80 and 230 ° C., preferably 80-190 ° C., and particularly preferably between 100 and 160 ° C., over a period of 5 minutes to 6 hours, preferably 10 minutes to 2 hours and particularly preferably 10 Minutes to 1 hour. The temperature treatment step can be carried out after the particles have been dried in a downstream dryer, and the desired water content of the particles can be obtained by spraying on water or a mixture consisting of water and one or more water-miscible organic solvents. However, the temperature treatment step is preferably carried out when the hydrogel particles are dried by first drying the hydrogel to a desired water content and then subjecting it to the temperature treatment. The temperature treatment can be carried out in a separate dryer or, preferably, in the same drying apparatus that was also used to dry the hydrogel to the desired water content. Without being tied to a theory, the inventors believe that in this

Heat treatment at the domain or region boundaries form the acid groups of the polymer I with the amino groups of the polymer II covalent amide bonds, so that there is an additional crosslinking.

In a particularly preferred embodiment of the invention, the hydrophilicity of the particle surface of the mixtures of polymers I and polymers II is additionally modified by the formation of complexes. The complexes are formed on the outer shell of the hydrogel particles by spraying on solutions of di- or polyvalent metal salt solutions and / or di- or polyvalent anions, the metal cations with the functional groups of the anionic polymer and the polyvalent anions with can react with the functional groups of the cationic polymer to form complexes. Examples of divalent or polyvalent metal cations are Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Sc ³⁺ , Ti ⁴⁺ , Mn ²⁺ , _Fe 2 + / 3 +, _Co 2 _{+ / Ni} 2 ₊ cu ⁺ / ²⁺ , Zn ²⁺ , Y ³⁺ , Zr ⁺ , Ag ⁺ , La ³⁺ , Ce ⁴⁺ , Hf ⁴⁺ , and Au ⁺ / ³⁺ , preferred metal cations are Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ and La ³⁺ , and particularly preferred metal cations are Al ³⁺ , Ti ⁴⁺ and Zr ⁴⁺ . Examples of divalent or polyvalent anions are sulfate, phosphate, borate and oxalate. Of the metal cations and the polyvalent anions mentioned, all salts are suitable which have sufficient solubility in the solvent to be used. Water, alcohols, DMF, DMSO and mixtures of these components can be used as solvents for the salts. Water and water / alcohol mixtures such as water / methanol or water / 1,2-propanediol are particularly preferred.

The salt solution can be sprayed onto the particles of the mixture of hydrogel-forming polymers I and II both before and after the surface post-crosslinking of the particles. In a particularly preferred method, the salt solution is sprayed on in the same step as the spraying of the crosslinking agent solution, with both solutions being sprayed on separately in succession or simultaneously via two nozzles, or the crosslinking agent and salt solution being sprayed together via a nozzle .

Optionally, a further modification of the particles of the mixture of polymers I and polymers II can be carried out by admixing finely divided inorganic solids, such as, for example, silica, bentonite, aluminum oxide, titanium dioxide and iron (III) oxide, which further enhances the effects of surface treatment become. The addition of hydrophilic silica or of aluminum oxide with an average size of the primary particles of 4 to 50 nm and a specific surface area of 50-450 m ² / g is particularly preferred. Fine inorganic solids are preferably added after the surface modification by crosslinking / complex formation, but can also be carried out before or during these surface modifications.

In a number of process steps, it can be useful to use additives. For the purposes of the present invention, additives are finely divided, powdery or fibrous substances which are inert to the manufacturing conditions of the components and the mixtures, and which can be organic or inorganic in nature. Examples of such additives are:

Fine-particle silicon dioxide, pyrogenic silicas, precipitated silicas in hydrophilic or hydrophobic modifications, zeolite, titanium dioxide, zirconium dioxide, talc, bentonites of all kinds, cellulose, silicates of all kinds, guar gum, tara flour, Johan Nisbrotkernmehl, all types of starches, clay, barium sulfate, calcium sulfate, synthetic and natural fibers.

They can be used both as process aids and as substrates.

The gels to be handled in the preparation of mixtures according to the invention are all sticky in more or less pronounced form. In order to overcome this disadvantage, it can be particularly useful when grinding, mixing or drying,

0.1 to 10 wt .-% of one or a combination of several of the additives mentioned before or during the process step. This measure covers the surface of the gels with the fine-particle additive, thus reducing or at least drastically reducing the stickiness. This addition also affects the properties of the end product. The fact that the dried powder particles are coated on the surface with the additive improves the flowability of the powders obtained. Furthermore, the dried gels tend to absorb water, particularly when they come into contact with a humid atmosphere, and thereby stick together. The addition of the additives mentioned above also reduces this adhesive effect. It may therefore make sense to add such additives to the end product first. This is the case if they are not required in the previous process steps.

To increase the surface area, to reduce the diffusion path and to make the functional groups of the gels more easily accessible, it can be useful to generate the above-mentioned acidic or basic gels on a support. Such a carrier must therefore have a large specific surface. The additives mentioned above have this property, in particular pyrogenic silicas, bentonites and talc are preferred. To produce such acidic or basic components, the carrier material can simply be added to the reaction mixture during the production of the components. As an alternative, there is the possibility of specifically coating the support material with the reaction mixture, e.g. by spraying in a fluidized bed. The amounts of carrier material used are between 5% and 80%.

Surfactants and blowing agents can also be used as auxiliaries.

The following test methods were used to investigate the polymer mixtures according to the invention: CRC (Centrifuge Retention Capacity):

To determine the CRC I, 0.2 g of polymer powder is weighed into a 60 x 85 mm tea bag, which is then sealed. The tea bag is then turned into an excess of

0.9% by weight saline solution (at least 0.83 1 saline solution / l g polymer powder). After 30 minutes of swelling, the teabag is removed from the saline solution and centrifuged at 250 g for three minutes. The amount of liquid held in place by the polymer powder is determined by weighing the centrifuged tea bag.

PUP 0.7 psi (Performance Under Pressure 0.7 psi):

The test method for determining the PUP 0.7 psi (pound / square inch, 0.7 psi = 4826.5 Pa) is described in the U.S. 5,599,335.

PUP 1.4 psi (Performance Under Pressure 1.4 psi):

The PUP 1.4 psi is determined in the same way as the PUP 0.7 psi, but under a weight load of 1.4 psi (9653 Pa).

PUP 0.014 psi (Performance Under Pressure 0.014 psi):

The PUP 0.014 psi is determined analogously to the determination of the PUP 0.7 psi, but under a weight load of 0.014 psi (96.5 Pa), i.e. without weight, only with the plastic insert for the weight.

SFC (Saline Flow Conductivity):

The test method for determining the SFC is described in U.S. 5,599,335.

SFC Index (Saline Flow Conductivity Index):

The SFC index is obtained from three SFC measurements with different weight loads using the following formula:

SFC index = [SFC (0.3 psi) • 10 ⁷ g / cm ³ s] ^• ([SFC (0.6 psi) • 10 ⁷ g / cm ³ s] + [SFC (0.9 psi) • 10 ⁷ g / cm ³ s])

The SFC (0.3 psi) corresponds to the SFC described above (0.3 psi = 2068.5 Pa). The SFC (0.6 psi) swells the hydrogel and measures the flow under a weight load of 0.6 psi (4137 Pa), with the SFC (0.9 psi) swelling and flow measurement are carried out at a weight load of 0.9 psi (6205.5 Pa).

PAI (NaCl) (Pressure Absorbency Index (NaCl)):

The pressure absorbency index (NaCl) is determined in accordance with the description of the PAI test method in EP-A-0 615 736, with the difference of a measurement time which is extended by up to 16 hours.

PAI (Jayco) (Pressure Absorbency Index (Jayco)

The determination of the Pressure Absorbency Index (Jayco) is carried out analogously to the determination of the Pressure Absorbency Index (NaCl) described above, but the liquid to be absorbed is, in deviation, a synthetic urine replacement solution with the following composition: 1000 g distilled water, 2.0 g KC1, 2, 0 g Na ₂ S0 ₄ , 0.85 g (NH ₄ ) H ₂ P0, 0.15 g (NH ₄ ) ₂ HP0 ₄ , 0.19 g CaCl ₂ , 0.23 g MgCl ₂ .

Diffusing Absorbency Under Pressure:

The method for determining the diffusing absorbency under pressure is carried out analogously to the description in EP-A-0712 659, but with the following modifications: the weight of polymer is 0.9 g instead of 1.5 g; the polymer sample is measured in the grain size range 106 - 850 μm; the weight load on the measurement is 0.7 psi (4826.5 Pa) instead of 0.3 psi (2068.5 Pa); the test solution is the synthetic urine replacement solution (see PAI) instead of 0.9% by weight saline; the measuring time is 4 hours instead of 1 hour.

Wicking performance:

The measurement of the wicking performance is carried out analogously to the measurement of the wicking parameter as described in the

EP-A-0 532 002. In contrast to the measurement of the Wikking parameter, the measurement of the wicking performance with 2 g polymer (particle size distribution 106 - 850 μm) is only carried out with a degree of pre-swelling of 10 g 0.9% by weight NaCl solution / lg polymer. guided. The wicking distance is measured, which indicates the length to which the polymer particles have swollen with the blue colored test liquid after a test time of 1 h and the Wikking capacity, which corresponds to the amount of liquid additionally taken up during this time.

Acquisition Time / Rewet under pressure: The examination is carried out on so-called laboratory pads. To produce these laboratory pads, 11.2 g of cellulose fluff and 23.7 g of hydrogel are swirled homogeneously in an air chamber and placed on a 12 x 26 cm mold by applying a slight negative pressure. This composition is then wrapped in tissue paper and pressed at a pressure of 20 bar for 2 times 15 seconds. A laboratory pad manufactured in this way is attached to a horizontal surface. The center of the pad is determined and marked. Synthetic urine replacement solution is applied through a plastic plate with a ring in the middle (inner diameter of the ring 6.0 cm, height 4.0 cm). The plate is loaded with additional weights so that the total load on the pad is 13.6 g / cm.2. The plastic plate is placed on the pad so that the center of the pad is also the center of the feed ring. 80 ml of synthetic urine replacement solution are applied three times. The synthetic urine replacement solution is prepared by dissolving 1.14 g of magnesium sulfate heptahydrate, 0.64 g of calcium chloride, 8.20 g of sodium chloride, 20 g of urea in 1 kg of deionized water. The synthetic urine replacement solution is measured in a measuring cylinder and applied to the pad in one shot through the ring in the plate. Simultaneously with the task, the time is measured which is necessary for the solution to penetrate completely into the pad. The measured time is noted as Acquisition Time 1. The pad is then loaded with a plate for 20 minutes, the load being kept at 13.6 g / cm2. After this time the plate is removed, 10 g ± 0.5 g of the filter paper (Schleicher & Schuell, 1450 CV) are placed on the center and with a weight (area 10 x 10 cm, weight 3.5 kg) for 15 s charged. After this time, the weight is removed and the filter paper is weighed back. The weight difference is noted as Rewet 1. Then the plastic plate with the feed ring is placed on the pad again and the second application of the liquid takes place. The measured time is noted as Acquisition Time 2. The procedure is repeated as described, but 45 g ± 0.5 g filter paper is used for the Rewet examination. Rewet 2 is noted. The same procedure is used to determine acquisition time 3. When determining Rewet 3, 50 g ± 0.5 g filter paper are used.

RAC factor (re-absorbing capacity factor of sheared gel)

For the determination (generally double determination) of the RACF, 1.2 g of polymer in an aluminum dish (diameter 4 cm, edge height 3 mm) are mixed with 12.0 g of 0.9% by weight NaCl solution and allowed to swell for 30 minutes, whereby during this time the sample is covered to protect it from drying out. 1.10 g of the pre- The gels are weighed into a plexiglass cylinder (inner diameter = 25 mm, height 33 mm) with a 140 μm sieve bottom and covered with a plexiglass disc. The cylinder with substance and disc is weighed, the weight registered as Wl. The plexiglass disc is then loaded with a metal weight (plexiglass disc + weight = 245 g, which corresponds to a pressure of 50 g / cm ² or 4905 Pa) and the entire measuring unit is placed in a 13 ml 0.9% by weight Petri dish filled with NaCl solution (diameter = 100 mm, height = 10 mm). After 60 minutes of swelling, the measuring unit is lifted out of the Petri dish, the weight is removed, excess saline solution adhering to the sieve bottom is stripped off, and the measuring cell is weighed back with swollen gel and Plexiglas disk, the weight registered as W2. The rest (11 g) of the pre-swollen gel after removal of the amount of gel for the double determination described above is transferred to a 30 x 150 mm polyethylene bag and the open side of the bag is vacuum-sealed. The bag is fixed on a film bag tester with an adhesive strip and then subjected to a roll-down test, which means that it is rolled over 50 times with a roll of 2 kg (25 times in the opposite direction). The mechanically loaded gel obtained in this way is now used in the same way as described above for absorption under a pressure load of 50 g / cm ² (re-absorbing capacity of sheared gel). The weight of the measuring cell with gel and disk before the 60 minute absorption is recorded as W3, the weight after absorption as W4. The re-absorbing capacity factor is now understood to be the ratio of absorption after to absorption before shear of the gel, multiplied by 100:

RAC-Factor = [(W4 - W3) / initial weight gel sheared / 10)] • 100 / [(W2 - Wl) / (initial weight gel unsheared / 10)]

DATGLAP 0.7 psi / 0.9 psi (Demand Absorbency Through Gel Layer Against Pressure 0.7 psi / 0.9 psi)

The method for determining DATGLAP is divided into two stages. In the first stage, an AUL (Absorption Under Load) is measured under a weight load of 0.7 psi (0.7 psi = 4826.5 Pa), for which purpose the same measuring cell and the same equipment are used and the procedure is almost identical to that for determining the PUP 0 , 7 psi, which is described in US 5,599,355. However, the DATGLAP / level 1 differs from the PUP in two points:

1. After sprinkling the test substance on the sieve bottom of the measuring cell, a plexiglass ring with a height of

0.32 cm, which is covered on its top with the same mesh as the bottom of the measuring cell. The Covered ring has an outer diameter of 5.98 cm so that it can be moved upwards without jamming / tilting in the measuring cell when the gel swells, an inner diameter of 4.9 cm and a height of 0.32 cm. The plastic cover plate with the weight is then placed on the covered ring, as described in the US patent cited above.

2. As a test solution at DATGLAP no synthetic urine, but 0.9 wt. -% saline solution used.

After a measurement period of 1 hour, a new measuring unit of the same type as described above (but smaller diameter, into the plexiglass cylinder) is placed on the covered plexiglass ring remaining in the measuring cell and resting on the gel after removing the weight and the plastic cover plate first measuring stage), set and left for 4 hours. The measurement of the liquid absorption begins again when the second measuring unit is placed on the sieve ring of the first measuring unit. The second measuring cell has the following dimensions: outer diameter = 5.98 cm / inner diameter = 5.03 cm. The test substance distributed on the sieve bottom of the second measuring cell is covered beforehand with a plexiglass disc (5.018 cm diameter) and loaded with a weight (plexiglass plate + weight = 1331 g —► 67.3 g / cm ² = 6606 Pa).

DATGLAP = (DAAP-TGL / DAAP-Regular) • (DAAP-Regular + DAAP-TGL) [g / g]

DAAP-TGL = Demand Absorbency Against Pressure Through Gel Layer after 4 hours, in [g / g]

= Measured value from 2nd stage with 2nd measuring cell

DAAP-Regular = Demand Absorbance Against Pressure after 1 hour, in [g / g] = measured value from 1st stage with 1st measuring cell

Polymer mixtures with an SFC index of at least 10,000, preferably> 100,000, in particular> 200,000 and particularly preferably 300,000 are preferred.

CRC, PUP 0.014 psi, PUP 0.7 psi and PUP 1.4 psi, PAI (NaCl) and PAI (Jayco) are test methods for characterizing the absorbency of the polymer mixture for aqueous saline solutions under different pressure loads. SFC, SFC index and Wicking performance describes the permeability of swollen gel layers. Diffusing Absorbency Under Pressure and DATGLAP provide test methods for the combined detection of ab- sorption capacity and fluid conduction. The RAC factor characterizes the mechanical stability of swollen polymer particles. The Acquisition Time / Rewet under pressure test simulates the behavior of the polymer mixture in hygiene articles such as 5 baby or incontinence diapers.

Furthermore, polymer mixtures with a Pressure Absorbency Index (NaCl) of> 100, preferably> 130, in particular 150 and particularly preferably 180 after a swelling time of 16 h, preferably of 4 h, are particularly suitable for use in hygiene articles.

In particular, polymer mixtures are preferred which have a Pressure Absorbency Index (Jayco) of at least 150, preferably> 15 200, in particular> 225 and particularly preferably> 250 after a swelling time of 16 h, preferably 4 h.

In addition, polymer mixtures with a diffusing absorbance under pressure of at least 30 g / g, preferably> 40 g / g, 20 in particular> 45 g / g and particularly preferably 50 g / g are advantageous.

Also advantageous are polymer mixtures which, in the wicking performance test, have a wicking distance of at least 5 cm, preferably> 25 8 cm, in particular 10 cm and particularly preferably 15 cm and a wicking capacity of at least 5 g, preferably 8 g, in particular 10 g particularly preferably have> 13 g.

Furthermore, polymer mixtures are preferred which, in the Acquisition 30 Time / Rewet under pressure test, have an Acquisition Time 3 of at most 25 s, preferably 20 s, in particular <15 s, very particularly <10 s and a Rewet 3 of at most 9 g, preferably < 5 g, in particular <3 g and particularly preferably <2 g.

Polymer mixtures are also preferred which have a RAC factor of at least 80, preferably> 90, in particular> 100 and particularly preferably> 120.

In addition, polymer mixtures with a DATGLAP of at least 40 at least 50 g / g, preferably 65 g / g, in particular> 80 g / g and very particularly preferably 90 g / g are advantageous.

In particular, polymers are preferred which have several of these preferred properties. Polymer mixtures with a 45 SFC index> 10,000 and a wicking distance of> 5 cm and a wicking capacity of at least 5 g are preferred. Polymer mixtures with an acquisition time 3 are particularly preferred of at most 25 s and a Rewet 3 of at most 9 g and an SFC> 10,000 and / or a diffusing absorbance under pressure of> 30 g / g. Polymer mixtures with an SFC index of> 1000, a PAI of> 150 after a 5 swelling time of 16 h, a diffusing absorbance under pressure of at least 30 g / g, a wicking distance of 5 cm and a Wikking are very particularly preferred Capacity of 5 g, an acquisition time 3 of at most 25 s and a rewet 3 of at most 9 g.

Polymer mixtures with polymers I based on acrylic acid and / or methacrylic acid are preferred.

Polymer mixtures whose polymer I is a crosslinked polyacrylic acid and whose carboxylic acid groups of 0 to 15-50% are present as an alkali and / or ammonium salt are preferred.

Polymer mixtures with crosslinked copolymers of acrylic acid or methacrylic acid with vinylsulfonic acid or acrylamidopropanesulfonic acid are also preferred as polymers I.

20th

Also preferred are polymer mixtures in which the polymers I have been crosslinked with oligo- or polyethylene glycol diacrylates or methacrylates, the molecular weight of which was 200 to 1000.

25

Preferred polymer mixtures are those in which polymer II is a polyethyleneimine, a polyamidoamine grafted with ethyleneimine, and / or polyamine grafted with ethyleneimine, which are crosslinked.

Polymer mixtures whose polymer II is a crosslinked polyvinylamine are also preferred.

Also preferred are polymer mixtures, the polymer II of which was obtained by copolymerization of vinylformamide and one or more mono-ethylenically unsaturated compounds, subsequent hydrolysis and optionally desalting and subsequent crosslinking.

Polymer mixtures are preferred, the polymer II of which is a graft copolymer of vinylformamide onto polymeric compounds, which has subsequently been hydrolyzed, optionally desalted and crosslinked.

Preferred polymer mixtures are those whose polymer II is a copolymer of vinylformamide and monoethylenically unsaturated mono- and / or polycarboxylic acids, which is then hydrolyzed. siert, optionally desalted and self-crosslinked by heating, that is, without the addition of crosslinker.

Preferred polymer mixtures are those whose polymer II is a copolymer of vinylformamide and monoethylenically unsaturated mono- and / or polycarboxylic acids which has been hydrolyzed, optionally desalted, has been crosslinked by heating and then with a cationic polymer or copolymer based on polyvinylamine or polyethyleneimine and / or with at least one bifunctional crosslinker was further crosslinked.

Also preferred are polymer mixtures, the polymer II of which is a polyethyleneimine, a polyamidoamine grafted with ethyleneimine or a polyamine grafted with ethyleneimine, which has been polymer-analogously modified by reaction with α, β-unsaturated carboxylic acids, their esters or by Strecker reaction and then thermally was networked with itself or at least one crosslinker.

Also preferred are polymer mixtures, the polymer II of which has been obtained by crosslinking a polyvinylamine with a K value of 40 to 220, in particular 70 to 160.

Also preferred are polymer mixtures whose polymer II has been prepared with one or more crosslinkers from groups (1), (5), (6), (7), (8) and (9).

Polymer mixtures with a ratio of the acid residues to the sum of amino / imino residues of 2: 1 to 1: 8 are preferred.

Polymer mixtures which are obtained by mixing polymer gel I and polymer gel II are preferred.

Polymer mixtures obtained by mixing polymer gel I and polymer powder II or polymer powder I and polymer gel II are particularly preferred.

Polymer mixtures which are obtained as a powder in the reaction mixture of the other component by adding a mixture component I or II are particularly preferred.

Polymer mixtures which contain polymer powder I, polymer powder II and agglomeration aids are also preferred.

Preferred polymer mixtures are those obtained by mixing surface post-crosslinked polymer I and surface post-crosslinked polymer II. The intraparticulate Lärischen mixtures with a domain structure, island structure and / or core-shell structure are preferred.

Polymer mixtures which are an agglomerated, surface post-crosslinked powder mixture are also preferred.

The polymer mixtures according to the invention have good application properties. They have an advantageous SFC index, good PAI values as well as table salt and Jayco. They also show excellent diffusing absorbency under pressure. They also get good results in the Wicking Performance test. Of particular note are their good values in the Acquisition Time / Rewet test under pressure.

The polymer mixtures according to the invention are notable for excellent absorbency for water and aqueous, salt-containing solutions, for high permeability of the swollen gel layers and for great mechanical stability of the swollen polymer particles and are therefore outstanding as absorbents for water and aqueous liquids, in particular body fluids ^'n, such as urine or blood suitable, for example in hygiene articles such as baby and adult diapers, sanitary napkins, tampons and the like. However, they can also be used as soil improvers in agriculture and horticulture, as moisture binders for cable sheathing and for thickening aqueous waste.

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

example 1

a) Preparation of a cross-linked polyacrylic acid

350 g (4.86 mol) of acrylic acid are dissolved together with 3.84 g of polyethylene glycol diacrylate of a polyethylene glycol of molecular weight 400 and 0.88 g of sodium peroxodisulfate in 1046.16 g of distilled water. The solution is transferred to a 2 liter Dewar at room temperature. The Dewar is closed with a stopper that carries a gas outlet and a gas inlet tube that reaches the bottom. Nitrogen is passed through the gas inlet tube for 30 minutes to remove the dissolved oxygen. Then 2.92 g of a 0.3% by weight ascorbic acid solution is added as a coinitiator and homogeneously mixed in by a vigorous stream of nitrogen. After the polymerization has started, the nitrogen flow is switched off and the gas inlet tube is removed from the Dewar pulled out. After reaction overnight, part of the gel block obtained was comminuted in a meat grinder and dried in a vacuum drying cabinet at 85 ° C. overnight in a vacuum. The second part was used for further tests without additional treatment. The dried gel was ground and the fraction was sieved with a particle size between 100 μm and 850 μm.

b) Preparation of a polyvinylamine crosslinked with ethylene glycol diglycidyl ether

2241 g of a 12.3% by weight aqueous polyvinylamine solution (K value 85) are homogeneously at room temperature with a solution of 13.77 g of ethylene glycol diglycidyl ether in 100 g of dist. Mixed water. The mixture is then heated in a water bath at 75 ° C. for 2 hours. Part of the gel obtained is used directly for further experiments, the rest is dried at 85 ° C. and vacuum overnight. The product obtained is ground and the fraction with a particle size between 100 μm and 850 μm is sieved off.

c) Preparation of the powder mixture

In each case 10 g of the sieved powder products obtained according to a) and b) were mixed homogeneously.

Example 2

Preparation of a gel-gel mixture

86.40 g undried, according to Example la) produced poly acrylsäuregel and 157.30 g undried according to Example lb Polyvinylamingels) produced are thereby intimately mixed with each other ge ^¬ that they are rotated together 3 times through a commercial meat grinder. The gel mixture obtained is dried in vacuo at 85 ° C. overnight. After grinding, the fraction with a particle size between 100 microns and 850 microns is sieved.

Example 3

64.8 g of undried polyacrylic acid gel produced according to Example la) and 183.5 g of undried polyvinylamine gel produced according to Example Ib) are mixed intimately by rotating them 3 times together through a commercially available meat grinder. The gel mixture obtained is at 85 ° C overnight dried in vacuo. After grinding, the fraction with a particle size between 100 microns and 850 microns is sieved.

Example 4

100 g of a 12.5% by weight aqueous polyvinylamine solution (K value 85) and a solution of 0.63 g of ethylene glycol diglycidyl ether in 4.38 g of dist. Water is mixed homogeneously at room temperature. Subsequently, 12.5 g of the powdery, crosslinked polyacrylic acid prepared according to Example la) are likewise homogeneously mixed in by vigorous stirring. The reaction mixture is heated to 75 ° C. in a water bath for 2 hours. The gel obtained is crushed, dried at 85 ° C. and vacuum overnight, ground and the fraction is sieved with a particle size between 100 μm and 850 μm.

Example 5

a) 100 g of a 13.6% strength by weight aqueous polyvinylamine solution (K value 85) and a solution of 0.41 g of N, N'-methylenebisacrylamide in 9.93 g of dist. Water is mixed homogeneously at room temperature. The reaction mixture is heated to 75 ° C. in a water bath for 2 hours. The gel obtained is crushed, dried overnight at 85 ° C. and vacuum, ground and the fraction is sieved off with a particle size between 100 μm and 850 μm.

b) In each case 10 g of the sieved powder products from Examples la) and 5a) were mixed homogeneously.

Example 6

a) 100 g of a 37.4% by weight aqueous polyethyleneimine solution (MW approx. 500000) is mixed homogeneously with 2.99 g of ethylene glycol diglycidyl ether at room temperature. The mixture is then heated in a water bath at 75 ° C. for 2 hours. Part of the gel obtained is used directly for further experiments, the rest is dried at 85 ° C. and vacuum overnight. The product obtained is ground with the addition of dry ice and the fraction with a particle size between 100 μm and 850 μm is sieved off.

b) In each case 10 g of the sieved powder products from Examples la) and 6a) were mixed homogeneously. The advantageous performance properties of the polymer mixtures according to the invention from Examples 1-6 are summarized in Table 0.

Table 0:

Example 7

a) In a polyethylene container with a capacity of 10 1, which is well insulated by foamed plastic material

3450 g of deionized water and 1400 g of acrylic acid submitted. 14 g of allyl methacrylate are added to this solution with stirring and the solution is rendered inert by passing nitrogen through it. The initiators, consisting of 0.57 g of 2,2′-azobisamidino-propanedihydrochloride, dissolved in 50 g of deionized water, 69 mg of hydrogen peroxide, dissolved in 50 g of deionized water and at a temperature of approx 27 mg of ascorbic acid, dissolved in 50 g of deionized water, added in succession and stirred. The reaction solution is then left to stand without stirring, a solid gel being formed by the onset of polymerization, in the course of which the temperature rises to approximately 92 ° C.

b) 1000 g of a 6% by weight aqueous polyvinylamine solution (K value 137) and a solution of 4.8 g of methylene bisacrylamide in

240 ml of deionized water are mixed homogeneously at room temperature. The reaction mixture is then kept at 80 ° C. for 6 hours without stirring, a solid gel being obtained.

c) The two gels are each mechanically comminuted and the comminuted gels are mixed together in a ratio of 1: 1, based on the solids content of the gels, by repeated coarse grinding. The mixed gel is dried in a vacuum drying cabinet at 80 - 100 ° C, ground and sieved at 106 - 850 μm.

The product has the following properties:

PUP 0.014 psi 55.2 g / g after 240 min PUP 0.7 psi 51.4 g / g after 240 min PUP 1.4 psi 41.7 g / g after 240 min CRC 20.7 g / g SFC 1055 x 10 ⁷ cm ³ s / g

SFC index

SFC (0.3 psi) 1055 x 10 " ⁷ cm ³ s / g SFC (0.6 psi) 315 x 10" ⁷ cm ³ s / g SFC (0.9 psi) 47 x 10 " ⁷ cm ³ s / g SFC Index 378745 PAI (NaCl)

AUL 0.01 psi 43.8 g / g after 240 min AUL 0.29 psi 41.6 g / g after 240 min AUL 0.57 psi 37.9 g / g after 240 min AUL 0.90 psi 34.9 g / g after 240 min PAI 158.2

AUL 0.01 psi 50.3 g / g after 16 h AUL 0.29 psi 47.8 g / g after 16 h AUL 0.57 psi 44.2 g / g after 16 h AUL 0.90 psi 40.7 g / g after 16 h PAI 183 , 0

PAI (Jayco)

AUL 0.01 psi 63.6 g / g after 240 min AUL 0.29 psi 58.1 g / g after 240 min AUL 0.57 psi 55.3 g / g after 240 min AUL 0.90 psi 52.9 g / g after 240 min PAI 229 , 9th

AUL 0.01 psi 70.4 g / g after 16 h AUL 0.29 psi 64.8 g / g after 16 h AUL 0.57 psi 61.9 g / g after 16 h AUL 0.90 psi 58.3 g / g after 16 h PAI 255.4

Diffusing Absorbency Under Pressure = 51.6 g / g

Wicking Performance: Wicking Distance = 11 cm

Wicking Capacity = 13.1 g

Acquisition Time / Rewet under pressure: Acquisition Time 1 = 38 s

Acquisition time 2 = 32 s

Acquisition time 3 = 13 s

Rewet 1 <0.1 g

Rewet 2 <0.1 g Rewet 3 <1.4 g

RAC factor = 101

DATGLAP = 86.2 g / g Production of surface post-crosslinked polymer I

Base polymer gel A

8.0 kg of pure acrylic acid are diluted with 24 kg of water in a 40 1 plastic bucket. 37 g are added to this solution

(0.457% by weight, based on acrylic acid), add pentaerythritol triallyl ether with stirring, and inertize the sealed bucket by passing nitrogen through it. The polymerization is then carried out by adding 4 g of 2,2′-azobis-amidinopropane dihydrochloride, dissolved in 100 ml of water, 460 mg of hydrogen peroxide and

170 mg of ascorbic acid, also each dissolved in 100 ml of water, started. Approximately The gel is mechanically comminuted 3 hours after the reaction has ended.

Polymer A0

The base polymer gel A is dried at 50 ° C. under vacuum in a drying cabinet, ground in a coffee grinder and finally sieved at 100-800 μm.

Polymer AI

The polymer gel A0 is sprayed in a Waring laboratory mixer with a crosslinking agent solution of the following composition: 2.5% by weight of 1,2-propanediol, 2.5% by weight of water, 0.2% by weight of ethylene glycol diglycidyl ether, based on polymer used. The moist product is then tempered at 120 ° C for 120 minutes in a circulating air drying cabinet. The dried product is sieved at 850 μm to remove lumps.

Polymer A2 The basic polymer gel A is mixed with sufficient sodium hydroxide solution until a degree of neutralization of 10 mol%, based on the acrylic acid used, is reached. The partially neutralized gel is then dried, ground, sieved and post-cross-linked analogously to the production of Al.

Polymer A3

The basic polymer gel A is mixed with as much sodium hydroxide solution until a degree of neutralization of 20 mol%, based on the acrylic acid used, is reached. The partially neutralized gel is then dried, ground, sieved and post-cross-linked analogously to the production of Polymer AI.

Polymer A4

The basic polymer gel A is mixed with sufficient sodium hydroxide solution until a degree of neutralization of 30 mol%, based on the acrylic acid used, is achieved. The partially neutralized gel will then dried, ground, sieved and post-crosslinked analogously to the preparation of polymer AI.

Polymer A5 The basic polymer gel A is mixed with sufficient sodium hydroxide solution until a degree of neutralization of 40 mol%, based on the acrylic acid used, is achieved. The partially neutralized gel is then dried, ground, sieved and post-cross-linked analogously to the production of Polymer AI.

Polymer A6

The basic polymer gel A is mixed with sufficient sodium hydroxide solution until a degree of neutralization of 40 mol%, based on the acrylic acid used, is achieved. The partially neutralized gel is then dried on a drum dryer, ground in a pin mill and sieved at 100-800 μm. The post-crosslinking is carried out in a Lödige mixer, a crosslinker solution of the following composition being sprayed onto 1 kg of polymer powder through a two-component nozzle: 4% by weight of methanol, 6% by weight of water, 0.2% by weight of 2 -Oxazolidinone, based on the polymer powder used. The moist product is then tempered at 180 ° C for 90 minutes in a circulating air drying cabinet. The dried product is sieved at 850 μm to remove lumps.

Polymer A7

The base polymer gel A is neutralized, dried and ground analogously to polymer A6. The powder is then sprayed with crosslinking agent solution in a Waring laboratory mixer. The solution is composed in such a way that the following dosage, based on the base polymer used, is achieved: 0.30% by weight of 2-oxotetrahydro-1,3-oxazine, 3% by weight of 1,2-propanediol , 7 wt .-% water, and 0.2 wt .-% boric acid. The moist polymer is then at 175 ° C for 60 min. dried.

Polymer A8

In a 5 1 polymerization flask, 1040 g of pure acrylic acid are diluted with 2827 g of deionized water. 5.2 g of allyl methacrylate are added to this solution with stirring, and the sealed flask is rendered inert by passing nitrogen through it. The polymerization is then carried out by adding 0.52 g of 2,2'-azdbisamino-dinopropane dihydrochloride, dissolved in 25 ml of fully deionized water, 165 mg of hydrogen peroxide, 35% by weight, dissolved in 12 g of deionized water and 20.8 mg of ascorbic acid , dissolved in 15 ml of fully demineralized water. Approximately 3 hours after the end of the reaction, the gel is broken up mechanically and at 50 ° C. Vacuum dried in a drying cabinet, ground in a coffee grinder, and finally sieved at 150 - 800 μm.

The polymer thus obtained is sprayed in a Waring laboratory mixer with 5 crosslinking agent solution having the following composition: 2.5% by weight of 1,2-propanediol, 2.5% by weight of water, 0.2% by weight of ethylene glycol digly- cidyl ether, based on the polymer used. The moist product is then tempered at 120 ° C for 120 minutes in a circulating air drying cabinet. The dried product is sieved at 850 μm to remove lumps.

Production of post-crosslinked polymer II

Polymer BI

15 In 2123 g 5.5% by weight salt-free polyvinylamine solution (K-

Value 137), 4.1 g of ethylene glycol diglycidyl ether was stirred in homogeneously at room temperature and the solution was heated at 60 ° C. overnight. The resulting gel was crushed mechanically, dried in vacuo at 80 ° C., ground and sieved at 150-800 μm. This

20 Polymer is sprayed with crosslinker solution in a Waring laboratory mixer. The solution is composed in such a way that the following dosage, based on the base polymer used, is achieved: 0.20% by weight of ethylene glycol diglycidyl ether, 2.5% by weight of 1,2-propanediol and 2.5% by weight of water. The moist polymer then becomes

25 120 ° C for 60 min. dried.

Base polymer B

621 g of a commercially available polyethyleneimine (POLYMIN ^® P, Brookfield viscosity at 20 ° C., approx. 22000 m Pas) is mixed with 279 g

30 least Mix the water into a homogeneous solution. 6.0 g of ethylene glycol diglycidyl ether, dissolved in 100 g of dist. Water, stirred in and homogenized. The mixture is then annealed in a covered form at 80 ° C. for 6 hours. The resulting gel is then mechanically crushed

35 80 ° C dried in vacuum, ground and sieved at 150-850 μm.

Polymer B2

The base polymer B is sprayed in a Waring laboratory mixer with a crosslinking agent solution of the following composition: 2.5% by weight

40 1,2-propanediol, 2.5% by weight of water, 0.2% by weight of ethylene glycol diglycidyl ether, based on the polymer used. The moist product is then tempered at 120 ° C for 120 minutes in a vacuum drying cabinet. The dried product is sieved at 850 μm to remove lumps.

45 Polymer B3

The base polymer B is sprayed with a crosslinking agent solution in a Waring laboratory mixer. The solution is composed such that the following dosage is achieved, based on the base polymer used: 0.20% by weight of glutaraldehyde, 3.0% by weight of 1,2-propanediol and 2.0% by weight of water. The moist polymer is then at 120 ° C for 60 min. dried and sieved at 850 μm.

Polymer B4 The base polymer B is sprayed with crosslinker solution in a Waring laboratory mixer. The solution is composed in such a way that the following dosage is achieved, based on the base polymer used: 0.5% by weight of polyamidoamine resin (Resamin ^® VHW 3608 from Hoechst AG), 2% by weight of 1, 2-propanediol and 3% by weight % Water. The moist polymer is then at 120 ° C for 6.0 min. dried and sieved at 850 μm.

Polymer B5

The base polymer B is sprayed with a crosslinking agent solution in a Waring laboratory mixer. The solution is composed such that the following dosage is achieved, based on the base polymer used: 0.2% by weight of 2-oxazolidinone, 3.0% by weight of 1, 2-propanediol and 2.0% by weight of water. The moist polymer is then at 180 ° C for 60 min. dried and sieved at 850 μm.

The polymers prepared according to the above examples were tested individually, the results are summarized in Table 1 below:

Table 1:

Examples 8.1 to 8.16

Homogeneous mixtures were produced from surface post-crosslinked polymers A and B. The polymers used in each case, their mixing ratios and the application results of the mixtures are shown in Table 2.

Surface post-crosslinking of mixtures of base polymer powders of polymers I and II:

Example 9.1 - 9.3

Polymer powders produced according to Examples A0 to A8 but without surface postcrosslinking were produced with polymer powders according to Examples B and BI (without described there

Surface postcrosslinking) homogeneously mixed and sprayed in a Waring laboratory mixer with crosslinking agent solution (2.5% by weight of 1,2-propanediol, 0.2% by weight of ethylene glycol diglycidyl ether and 2.5% by weight of water) and then at 120 ° C dried for 60 minutes. The types of polymer used, mixing ratios and test results are summarized in Table 3 below.

Table 2:

Performance data of the powder mixtures made from post-crosslinked polymers I and II

t

in

Table 3:

Surface post-crosslinking of mixtures of base polymer powders of polymers I and II

without surface post-crosslinking

Example 10

100 g of a graft copolymer based on polyethylene glycol with 5 average molecular weight 9000 (70 g) and N-vinylformamide (30 g) with a K value of 42 was diluted with 900 g of deionized water, with 20 g of a 40 wt. -% sodium bisulfite solution and 67 g of a 25 wt. -% aqueous sodium hydroxide solution stirred at 80 ° C. A further 20.1 g of 25 wt. -% NaOH solution added. The degree of hydrolysis was 81.4% of theory determined at pH 3.5 with polyelectrolyte titration. This polymer solution was desalted by means of ultrafiltration on a membrane (exclusion limit 3000 D).

15 200 g of a polymer solution desalinated in this way (non-volatile content 5%) were mixed with 0.2 g of acrylic acid and crosslinked at 175 ° C. in a tub coated with Teflon for 10 minutes in a vacuum drying cabinet. The polymer thus obtained was dry and could easily be ground. A 1: 1 powder mixture of this

20 polymers and a cross-linked polyacrylic acid (base polymer A0) were examined for their application properties.

Intake capacity (30 min) [g / g]: 32.7

25

Absorption capacity (4 h) [g / g]: 46.3

CRC (30 min) [g / g]: 19.2

30 AAP (0.7 psi) [g / g]: 17.0

Example 11

50 g of a high molecular weight polyethyleneimine (average molecular weight 35,500,000) with a solids content of 49.5% by weight were mixed with 100 parts of a copolymer of acrylamide (98 g) and hydroxyethyl acrylate (2 g) K value 72.1 and a solids content of 14.8% by weight and kneaded in a laboratory kneader from Jahnke & Kunkel for 1 hour. The gel was dried in a vacuum at 70 ° C. for 24 h and then ground.

A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid (according to Example la) was examined for its absorbent properties. 45

Absorption capacity (30 min) [g / g]: 26.5 CRC (30 min) [g / g]: 10.4

AAP (0.3 psi) [g / g]: 17.6

Example 12

600 g of a fully desalinated polyvinylamine homopolymer with a K value of 91, a degree of hydrolysis of 90.1% and a solids content of 4% by weight were mixed in a laboratory kneader with 1 g of acrylic acid and at a temperature of 100 ° C. networked. During this time, a further 600 g of the polyvinylamine were added and a total of 490 g of water were distilled off. After a period of 5 hours the polymer was insoluble in water. The gel was then dried at 75 ° C. in vacuo for 24 h and then ground. A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid (base polymer A0) was tested.

Intake capacity (30 min) [g / g]: 30.3

CRC (30 min) [g / g]: 15.1

CRC (4 h) [g / g]: 23.3

Recording capacity (4h) [g / g]: 42, 0

AAP (0.7 psi) [g / g]: 16.2

PUP (0.7 psi Jayco) [g / g]: 15.3

PUP (0.7 psi Jayco, 4 h) [g / g]: 22, 3

Example 13

500 g of a fully desalinated polyvinylamine homopolymer with a K value of 85, a degree of hydrolysis of 92.1% and a solids content of 6.7% by weight were mixed in a laboratory kneader with 1 g of methyl acrylate and at one temperature networked from 100 ° C. During this time, a further 500 g of the polyvinylamine were added and a total of 360 g of water were distilled off. After a period of 5 hours the polymer was insoluble in water. The gel was then dried at 75 ° C. in vacuo for 24 h and then ground. A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid (base polymer A0) was tested as a super absorber.

Absorption capacity (30 min) [g / g]: 28.7 CRC (30 min) [g / g]: 17.9

AAP (0.3 psi) [g / g]: 15.3

Example 14

200 g of a fully desalinated polyvinylamine homopolymer solution (non-volatile content 5%) were mixed with 0.4 g urea and crosslinked in a Teflon-coated tub at 175 ° C. for 10 minutes in a vacuum drying cabinet. After a further drying step at 185 ° C., the polymer obtained in this way was brittle and dry and could easily be ground.

A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid from Example la) was tested.

Absorption capacity (30 min) [g / g]: 24.9

CRC (30 min) [g / g]: 10.1

Absorption capacity (4h) [g / g]: 41.9

CRC (4 h) [g / g]: 16.5

AAP (0.7 psi lh) [g / g]: 15.6

Example 15

200 g of a fully desalinated polyvinylamine homopolymer solution (non-volatile content 5%) were mixed with 0.4 g propylene carbonate and crosslinked in a Teflon-coated tub at 175 ° C. for 10 minutes in a vacuum drying cabinet. After a further drying step at 185 ° C., the polymer obtained in this way was brittle and dry and could easily be ground.

A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid from Example la) was tested as a superabsorbent.

Intake capacity (30 min) [g / g]: 25.0 CRC (30 min) [g / g]: 10.6

Absorption capacity (4h) [g / g]: 40.6

CRC (4 h) [g / g]: 16.8

AAP (0.7 psi lh) [g / g]: 16.4 Example 16

668.9 g of a desalted polyvinylamine with KW 137 (non-volatile fraction 2.8%) are crosslinked with themselves in a teflon-coated pan in a vacuum drying cabinet at 185 ° C. for 2 hours. The resulting product can be peeled off like a film. This gives about 20 g of solid polymer which has been ground in an analytical mill.

A 1: 1 powder mixture of this polymer and a crosslinked polyacrylic acid (according to Example la) was examined for its absorbent properties.

Absorption capacity (30 min) [g / g]: 48.5 Recording capacity (4 h) [g / g]: 64.3 CRC (30 min) [g / g]: 25.4 AAP (0.7 psi lh) [ g / g]: 16.8

Example 17

337.3 g of a desalted polyvinylamine with KW 137 (non-volatile content 2.5%) are mixed with 33.37 g of a 25 wt. % polyacrylic acid gel according to Example la (fixed content ratio 1: 1) mixed at room temperature in a laboratory kneader from Jahnke & Kunkel for 45 minutes. Then it is crosslinked in a vacuum drying cabinet in a pan coated with Teflon at 180 ° C. under a stream of nitrogen at 400 mbar in 1.5 hours. The product was ground in an analytical mill and then sieved through a 500 μ sieve. The absorbent properties of this solid polymer were:

On absorption capacity (30 min) [g / g]: 35.1 absorption capacity (4 h) [g /]: 43.9 CRC (30 min) [g / g]: 11.8 AAP (0.7 psi lh) [g / g]: 23, 8

Example 18

200 g of a desalted polyvinylamine (non-volatile content 2.5%) (in the solid content ratio of polyvinylamine to superabsorber 4: 6) are mixed with 30 g of 25% polyacrylic acid gel according to Example 1a at room temperature in a duplex kneader for 1 hour and then for 1.5 hours crosslinked in a pan coated with Teflon at 400 mbar under nitrogen flow at 180 ° C. The product was ground in an analytical mill and then sieved through a 500μ sieve. The absorbent properties of this solid polymer were:

Intake capacity (30 min) [g / g]: 30.6 Intake capacity (4 h) [g / g]: 38.4 CRC (30 min) [g / g]: 11.2 AAP (0.7 psi) [ g / g]: 21.6

Claims

claims

1. Containing hydrogel-forming polymer mixture

a) a hydrogel-forming polymer I with acid residues and

b) a hydrogel-forming polymer II with amino and / or imino residues,

wherein the ratio of the acid residues to the sum of amino / imino residues is 1: 9 to 9: 1.

2. Hydrogel-forming polymer mixture according to claim 1, characterized in that the hydrogel-forming polymer I is crosslinked polyacrylic acid, the carboxylic acid groups of 0 to 50% are present as alkali and / or ammonium salt.

3. Hydrogel-forming polymer mixture according to claim 1 or 2, characterized in that the hydrogel-forming polymer II is cross-linked and is a polyethyleneimine, a polyamidoamine grafted with ethyleneimine and / or polyamine grafted with ethyleneimine.

4. Hydrogel-forming polymer mixture according to claim 1 or 2, characterized in that the hydrogel-forming polymer II is a crosslinked polyvinylamine.

5. Hydrogel-forming polymer mixture according to claim 4, characterized in that the hydrogel-forming polymer is a polyvinylamine with a degree of hydrolysis of 70-100, which was then thermally post-crosslinked.

6. Hydrogel-forming polymer mixture according to claims 1 or 2, characterized in that the hydrogel-forming polymer

II by copolymerization of vinylformamide and one or more monoethylenically unsaturated compounds, subsequent hydrolysis and optionally desalting and subsequent crosslinking.

7. hydrogel-forming polymer mixture according to claim 1 or 2, characterized in that the hydrogel-forming polymer II is a graft copolymer of vinylformamide on polymeric compounds, which was then hydrolyzed, optionally desalted and crosslinked.

8. hydrogel-forming polymer mixture according to claims 1, 2 and 6, characterized in that the hydrogel-forming polymer II is a copolymer of vinylformamide and monoethylenically unsaturated mono- and / or polycarboxylic acids

5, which was then hydrolyzed, optionally desalted and crosslinked by heating.

9. hydrogel-forming polymer mixture according to claims 1, 2 and 6, characterized in that the hydrogel-forming

10 Polymer II is a copolymer of vinylformamide and monoethylenically unsaturated mono- and / or polycarboxylic acids, which has been hydrolyzed, optionally desalted, crosslinked by heating and then with a cationic polymer or copolymer based on polyvinylamine or poly-

15 ethyleneimine and / or with at least one bifunctional crosslinker.

10. Hydrogel-forming polymer mixture according to claims 1 to 3, characterized in that polymer II is a polyethylene

20 min, a polyamidoamine grafted with ethyleneimine or a polyamine is that which has been polymer-analogously modified by reaction with α, β-unsaturated carboxylic acids, their esters or by Strecker reaction and has subsequently been crosslinked thermally.

25

11. Hydrogel-forming polymer mixture according to claim 1 with an SFC index of> 10,000.

12. Hydrogel-forming polymer mixture according to claim 1 with a 30 PAI index (NaCl) of> 100 after a swelling time of 16 h.

13. Hydrogel-forming polymer mixture according to claim 1 with a PAI index (Jayco) of> 150 after a swelling time of 16 h.

35 14. Hydrogel-forming polymer mixture according to claim 1 with a diffusing absorbance under pressure of> 30 g / g.

15. Hydrogel-forming polymer mixture according to claim 1 with a wicking distance 5 in the wicking performance test and one

40 wicking capacity of at least 5 g.

16. Hydrogel-forming polymer mixture according to claim 1 with an acquisition time 3 of <25 s and a rewet 3 of at most 9 g in the acquisition time / rewet test under pressure.

45

17. A hydrogel-forming polymer mixture according to claim 1 with a RAC factor of at least 80.

18. Hydrogel-forming polymer mixture according to claim 1 with a 5 DATGLAP of at least 50 g / g.

19. A hydrogel-forming polymer mixture according to claim 1, which is obtained by mixing polymer gel I and polymer powder II or polymer powder I and polymer gel II.

10

20. The hydrogel-forming polymer mixture according to claim 1, which is obtained by adding a mixture component I or II as a powder in the reaction mixture of the other component.

15 21. Hydrogel-forming polymer mixture according to claim 1, which is obtained by self-crosslinking the polyvinylamine with a degree of hydrolysis of 70-100 when drying a mixture of the polymers I and II at temperatures of 80-200 ° C.

22. Use of the hydrogel-forming polymer mixture according to claim 1 as an absorbent for water and aqueous liquids.

23. Use of the hydrogel-forming polymer mixture according to claim 1 in hygiene articles which are used to absorb body fluids.

30

35

40

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