WO2009056543A1

WO2009056543A1 - Composite material made of a super-absorber and a carrier material and method for the production thereof by impregnation

Info

Publication number: WO2009056543A1
Application number: PCT/EP2008/064606
Authority: WO
Inventors: Hans-Jürgen QUADBECK-SEEGER; Ulrike Licht; Ernst Jürgen BAUER; Timo Baumgärtner; Antje Ziemer; Armin Alteheld
Original assignee: Basf Se
Priority date: 2007-10-30
Filing date: 2008-10-28
Publication date: 2009-05-07
Also published as: DE112008002839A5

Abstract

The present invention relates to a composite material, which comprises at least one super-absorbent polymer and at least one elastic foamed aminoplast resin as a carrier material, hygiene products, sealing materials, insulation materials, desiccants, water reservoirs, packages, and artificial plant substrates, which contain said composite material, and to a method for producing a composite material, which contains at least one super-absorbent polymer and at least one elastic foamed aminoplast resin as a carrier material, comprising the steps: (A) providing the at least one carrier material, (B) impregnating the at least one carrier material from step (A) using a solution or emulsion of monomers, from which the at least one super-absorbent polymer is synthesized, and (C) polymerizing the monomers from step (B) on or in the carrier material.

Description

Composite material of a superabsorbent and a carrier material and method for its production by impregnation

The present invention relates to a composite material comprising at least one superabsorbent polymer and at least one elastic aminoplast foam, i. a foamed aminoplast elastic resin, as a carrier material, the use of such a composite material in the hygiene sector, in agriculture, in the automotive sector, in the furniture sector, as a sealing material, in the cosmetics sector, for packaging or as an artificial plant substrate, and a method for producing such a composite material.

Superabsorbent polymers are known in the art. These are crosslinked hydrophilic polymers, in particular polymers of polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable graft, crosslinked cellulose or starch ethers, crosslinked carboxymethylcellulose, partially crosslinked polyalkylene oxide or in aqueous products swellable natural products, such as guar derivatives, wherein water-absorbing polymers based on partially neutralized acrylic acid are the most widespread. The essential properties of superabsorbents are their ability to absorb many times their own weight in aqueous liquids and to not release the liquid under some pressure. The superabsorber (SAP, superabsorbent polymer), which is used in the form of a dry powder, transforms into a gel when taken up by liquid, correspondingly into a hydrogel in the case of the usual absorption of water. By far the most important application of superabsorbents is the absorption of body fluids. Superabsorbents are used, for example, in infant diapers, adult incontinence products or feminine hygiene products. Other fields of application are, for example, the use as water retention agents in agricultural horticulture, as water storage for protection against fire, for liquid absorption in food packaging or, more generally, for the absorption of moisture.

Methods are known in the prior art for applying superabsorbent polymers to support materials so as to ensure easy handling and processing of the superabsorbent material.

DE 601 04 818 T2 discloses a superabsorbent article in which a solution comprising mono-, based on a carrier layer consisting of a fleece of plastic fibers mers, from which the superabsorbent polymers are built up, and other additives are applied. After application of the monomers mentioned, the impregnated nonwoven fabric is exposed to conditions under which the monomers are converted to the superabsorbent polymers to give a nonwoven surface coated with superabsorbent polymers on the surface and also inside.

DE 102 31 356 A1 discloses water-absorbing, foam-like polymer structures which are applied to various carrier materials, e.g. Metal, fleece or fluff are applied. The application is carried out according to this document by contacting the water-absorbing polymers and the support materials.

WO 2006/066752 A2 discloses polyurethane foams which contain superabsorbent polymers. These are obtained by polymerizing the precursor compounds of the polyurethane foams in the presence of the superabsorbent polymers to give the corresponding polyurethanes.

US 2006/0252899 A1 discloses a process in which partially polymerized SAP particles are applied to a nonwoven as carrier material and polymerized there to give the finished superabsorbent polymer.

DE 10034505 describes the use of open-cell foams based on melamine-formaldehyde resins in hygiene articles. It is further disclosed in this document that a sanitary article is made up of a liquid-impermeable layer, a liquid-permeable layer and an absorbent intermediate layer, the intermediate layer serving for receiving, distributing and immobilizing liquids. Furthermore, there is a storage layer of a highly swellable hydrogel, which may also be incorporated in an open-cell foam, but this foam is not specified in more detail.

It is known that open-cell, flexible foams based on melamine-formaldehyde condensates can be hydrophilically modified in order to be able to absorb water-based liquids more quickly.

DE 10047717 describes hydrophilic open-cell foams based on melamine-formaldehyde condensates, which are obtained after the preparation of the carrier foam by applying a hydrophilizing reagent, and the use in hygiene articles. Foams are known from WO-A-96/21682 which, because of their open-cell structure with relatively large openings and channels, are outstandingly suitable for absorbing aqueous body fluids, in particular for absorbing blood. The foams are obtained by polymerization of (C ₄ -C ₄₎ -alkyl, (C ₆ -C ₆₎ - alkyl methacrylates, (C ₄ -C ₂₎ -Alkylstyrolen as monomers, preferably styrene and ethyl styrene as comonomers, also aromatic polyvinyl compounds as a crosslinker; optionally polyfunctional acrylates, methacrylates, acrylamides and methacrylamides and mixtures thereof as additional crosslinker substances.

WO-A-97/07832, US-A-5,318,554 and US-A-5,550,167 relate to the preparation of open-celled foams based on HIPE emulsions and their use in hygiene articles for the absorption of aqueous body fluids. However, the open-celled foams are always used together with other components that take over storage in the hygiene article.

From WO-A-99/26670 absorbent foams are known which consist of materials known in the art for the preparation of highly swellable hydrogels (for example crosslinked polyacrylates) in water, and for the purpose of producing open-cell foams the costly and costly method of freezing be subjected to drying. Due to their composition, such foams require no additional absorbent components, but are expensive to produce.

In the prior art, no method is known with which superabsorbent polymers can be applied to elastic aminoplast foams. Furthermore, no aminoplast foam product is known which has superabsorbent polymers in the pores and / or on the surface.

The object of the present invention is to provide a composite material which has superabsorbent properties and, at the same time, is in a sufficiently stable form for the corresponding applications. Another object of the present invention is to provide a composite material containing a carrier material capable of distributing a liquid incident on only a small portion of the material to the entire superabsorbent material. It is also an object of the present application to provide a method for producing such a composite material. These objects are achieved by providing a composite material comprising at least one superabsorbent polymer and at least one elastic foamed aminoplast resin as support material. Furthermore, the objects of the present invention are achieved by hygiene products, sealing materials, insulating materials, drying agents, water storage, packaging and artificial plant substrates containing the composite material according to the invention, by the use of this composite material, and by a method for producing the composite material according to the invention comprising at least a superabsorbent polymer and at least one elastic foamed aminoplast resin as carrier material comprising the steps:

(A) providing the at least one carrier material,

(B) impregnating the at least one support material from step (A) with a solution or emulsion of monomers from which the at least one superabsorbent polymer is built up and

(C) polymerizing the monomers from step (B) on or in the support material.

The individual steps of the method according to the invention for producing the composite material are explained in more detail below:

Step (A):

Step (A) of the method according to the invention comprises providing the at least one carrier material.

Suitable carrier materials in the process according to the invention can generally be any of the foamed, elastic aminoplast resins known to those skilled in the art, ie elastic aminoplast foams. Aminoplast resins are generally understood as meaning polycondensation products of carbonyl compounds, in particular formaldehyde, and compounds containing NH groups, for example urea, melamine, urethanes, cyano and dicyanamide, dicyandiamide, aromatic amines and sulfonamides. It is important to ensure that the starting materials are readily soluble or dispersible in water. When used as thermosets, these are cured, see Römpp, Chemielexikon, 9th edition, p. 159. In a preferred embodiment, the carrier material used is a foamed melamine-formaldehyde resin, particularly preferably porous amino resins in the form of foams. The foams may be open-celled or have closed pores or have both open and closed pores. Open-cell foams are preferably used, particularly preferably with an open-cell speed of> 90%, very particularly preferably> 99%. The production of aminoplast resin foams is known to the person skilled in the art. Very particular preference is given to open-cell elastic foams based on melamine / formaldehyde condensation products.

In the production of these foams one starts from a melamine / formaldehyde precondensate. Melamine / formaldehyde condensation products may contain not only melamine but also up to 50% by weight, preferably up to 20% by weight, of other thermoset formers and, in addition to formaldehyde, up to 50% by weight, preferably up to 20% by weight, of other aldehydes. Preferred is an unmodified melamine / formaldehyde condensation product. Suitable thermoset formers are, for example: alkyl- and aryl-substituted methylamine, urea, urethanes, carboxamides, dicyandiamide, guanidine, sulfurylamide, sulfonamides, aliphatic amines, glycols, phenol and derivatives thereof. As aldehydes, e.g. Acetaldehyde, trimethylolacetaldehyde, acrolein, benzaldehyde, furfurol, glyoxal, glutaraldehyde, phthalaldehyde and terephthalaldehyde. Further details about melamine / formaldehyde condensation products are disclosed in Houben-Weyl, Methods of Organic Chemistry, Vol. 14/2, 1963, pp. 319-402.

The molar ratio of melamine to formaldehyde is generally within wide limits between 1: 1, 0 and 1: 5.0. In a preferred embodiment, the molar ratio of melamine to formaldehyde is greater than 1, 0: 2.0, more preferably between 1, 0: 1, 0 and 1, 0: 1, 9, most preferably between 1, 0: 1 , 3 and 1, 0: 1, 8.

Said melamine resin may contain condensed sulfite groups, which can be done for example by the addition of 1 to 20 wt .-% sodium bisulfite in the condensation of the resin. In a preferred embodiment, however, the sulfite group content is below 1%, more preferably below 0.1%, and most preferably at 0%.

The open-celled melamine / formaldehyde foam which is preferably used as the carrier material in the process according to the invention can be obtained by reacting an aqueous melamine / formaldehyde foam

Solution or dispersion which contains a melamine / formaldehyde precondensate, an emulsifier, a blowing agent and a hardener, and optionally conventional additives, foamed and then cross-linked, wherein the solution or dispersion is expanded by heating to the desired foam.

In order to produce a foam from the melamine resin solution, it must contain a blowing agent, the amount depending on the desired density of the foam. In principle, both physical and chemical blowing agents can be used in the production of the foam. Suitable physical blowing agents are, for example: hydrocarbons, halogenated, in particular fluorinated hydrocarbons, alcohols, ethers, ketones and esters in liquid form or air and CO ₂ as gases. Examples of suitable chemical blowing agents are isocyanates in admixture with water, CO _{2 being} released as the effective blowing agent, furthermore carbonates and carbonate mixed with acids which likewise produce CO ₂ , and azo compounds, such as azodicarbonamide. In a preferred embodiment of the production of the foam, the aqueous solution or dispersion is added between 1 and 40% by weight, based on the resin, of a physical blowing agent having a boiling point between 0 and 80 ^° C. For pentane, it is preferably 5 to 15 wt .-%. Hardeners used are acidic compounds which catalyze the further condensation of the melamine resin. The amounts are between 0.01 and 20, preferably between 0.05 and 5 wt .-%, based on the resin. In question are inorganic and organic acids, for example hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, oxalic acid, toluenesulfonic acids, amidosulfonic acids and acid anhydrides.

To emulsify the blowing agent and to stabilize the foam, the addition of an emulsifier or an emulsifier mixture is required. Anionic, cationic and nonionic surfactants and mixtures thereof can be used as the emulsifier.

Suitable anionic surfactants are diphenylene oxide sulfonates, alkane and alkylbenzenesulfonates, alkylnaphthalenesulfonates, olefinsulfonates, alkyl ether sulfonates, fatty alcohol sulfates, ether sulfates, alpha-sulfofatty acid esters, acylaminoalkanesulfonates, acyl isethionates, alkyl ether carboxylates, N-acyl sarcosinates, alkyl and alkyl ether phosphates. Nonionic surfactants which can be used are alkylphenol polyglycol ethers, fatty alcohol polyglycol ethers, fatty acid polyglycol ethers, fatty acid alkanolamides, EO / PO block copolymers, amine oxides, glycerol fatty acid esters, sorbitan esters and alkylpolyglucosides.

The cationic emulsifiers used are trialkylammonium salts, alkylbenzyldimethylammonium salts and alkylpyridinium salts. The emulsifiers are preferably added in amounts of 0.2 to 5 wt .-%, based on the resin. The aqueous solution or dispersion for producing the foam used as a carrier material is preferably free of further additives. For some purposes, however, it may be beneficial, up to 20 wt .-%, preferably less than 10 wt .-%, based on the resin, conventional additives such as dyes, flame retardants, UV stabilizers, means for reducing the burn gas toxicity or Promotion of charring add.

Liquids, such as water, should preferably be included in the composite material made according to the present invention by the present superabsorbent polymer and not by the carrier material. Therefore, it may be useful to add in the preparation of water repellents in amounts of 0.2 to 5 wt .-%. Suitable water repellents are, for example, silicones, paraffins, silicone and fluorosurfactants.

The preparation of the support material used according to the invention can preferably be carried out according to the process mentioned in WO 01/94436 A2. The heating of the blowing agent-containing solution or dispersion can in principle be carried out by hot gases or high-frequency radiation. Preferably, the required heating is performed by ultra-high frequency radiation at frequencies of 0.2 GHz to 100 GHz. For industrial practice frequencies of 0.915, 2.45 and 5.8 GHz are available, with 2.45 GHz being particularly preferred.

After production, the foams used according to the invention are expediently subjected to a temperature treatment. They are doing 1 to 180 min., Preferably 5 to 60 min. heated to temperatures between 120 and 300 ⁰ C, preferably between 150 and 250 ⁰ C, wherein water, blowing agent and formaldehyde are largely removed.

The elastic foams preferably used according to the invention as carrier material, which preferably contain virtually no sulfite groups, have a density of from 3 to 50 g / cm ³ , more preferably from 5 to 15 g / cm ³ .

The foams obtained in this way can be tempered and pressed, as described in EP B 37470, in order to produce or improve their properties desired for the composite material according to the invention. The carrier material can be produced as plates or webs with a height of up to 2 m or obtained as foam film with a thickness of a few millimeters. The preferred foam height in the foam direction is between 50 cm and 150 cm when using 2.45 GHz frequency microwaves. From these foam sheets all desired sheet or film thicknesses can be cut out and used as a carrier material in step (A) of the method according to the invention.

Step (B):

Step (B) of the process according to the invention comprises impregnating the at least one support material from step (A) with a solution or emulsion of monomers from which the at least one superabsorbent polymer is made up.

Preferably, a solution is used in step (B).

The superabsorbent contained in the composite material according to the invention is a common superabsorber, which can absorb a multiple of its own weight of water and retain it under some pressure. In general, it has a CRC ("Centrifuge Retention Capacity", measuring method see below) of at least 5 g / g, preferably at least 10 g / g and in a particularly preferred form at least 15 g / g Preferably, the superabsorber is a cross-linked A polymer based on partially neutralized acrylic acid, and in a particularly preferred form it is surface-postcrosslinked A "superabsorber" can also be a mixture of materially different individual superabsorbers, it depends less on the material composition than on the superabsorbent properties.

Processes for the production of superabsorbents, including surface postcrosslinked superabsorbers, are known.

In a preferred embodiment, the at least one superabsorbent polymer is a homo- or copolymer containing unsaturated mono- or dicarboxylic acids.

Synthetic superabsorbent polymers are obtained, for example, by polymerization of a monomer solution containing

a) at least one ethylenically unsaturated, acid group-carrying monomer, b) at least one crosslinker, c) optionally at least one ethylenically and / or allylically unsaturated monomer copolymerizable with the monomer a) and d) optionally at least one or more water-soluble polymers to which the monomers a), b) and optionally c) can at least partially be grafted,

receive.

Suitable monomers a) are, for example, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, or their derivatives, such as acrylamide, methacrylamide, acrylic esters and methacrylic esters, or salts thereof, for example alkali metal salts of acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid , preferably the lithium, sodium or potassium salts. Particularly preferred monomers are acrylic acid and methacrylic acid and their sodium salts. Very particular preference is given to acrylic acid and the sodium salt of acrylic acid.

The stated monomers a) are preferably present in the solution according to the invention in an amount of from 10 to 60% by weight, preferably from 20 to 55% by weight, in each case based on the total solution or emulsion.

The monomers a), in particular acrylic acid, preferably contain up to 0.025 wt .-% of a Hydrochinonhalbethers. Preferred hydroquinone half ethers are hydroquinone monomethyl ether (MEHQ) and / or tocopherols.

Tocopherol is understood as meaning compounds of the following formula (I)

where R ^{1 is} hydrogen or methyl, R ^{2 is} hydrogen or methyl, R ^{3 is} hydrogen or methyl and R ^{4 is} hydrogen or an acid radical having 1 to 20 carbon atoms. Preferred radicals for R ⁴ are acetyl, ascorbyl, succinyl, nicotinyl and other physiologically acceptable carboxylic acids. The carboxylic acids can be mono-, di- or tricarboxylic acids.

Preference is given to alpha-tocopherol with R ¹ = R ² = R ³ = methyl, in particular racemic aallpphhaa - toooccoopphheeroll .. RR ⁴⁴ iisstt bbeessoonnddeerrss preferred hydrogen or acetyl. Especially preferred is RRR-alpha-tocopherol.

The monomer solution or emulsion used in step (B) of the process according to the invention preferably contains at most 130 ppm by weight, more preferably at most 70 ppm by weight, preferably at least 10 ppm by weight, particularly preferably at least 30% by weight. ppm, in particular by 50 ppm by weight, hydroquinone, in each case based on acrylic acid, wherein acrylic acid salts are taken into account as acrylic acid with. For example, an acrylic acid having a corresponding content of hydroquinone half-ether can be used to prepare the monomer solution.

The crosslinkers b) are compounds having at least two polymerizable groups which can be incorporated in the polymer network by free-radical polymerization. Suitable crosslinkers b) are, for example, ethylene glycol dimethacrylate, diethylene glycol diacrylate, allyl methacrylate, trimethylolpropane triacrylate, triallylamine, tetraallyloxyethane, as described in EP 530 438 A1, di- and triacrylates, as in EP 547 847 A1, EP 559 476 A1, EP 632 068 A1, WO 93/21 237 A1, WO 03/104 299 A1, WO 03/104 300 A1, WO 03/104 301 A1 and DE 103 31 450 A1, mixed acrylates which, in addition to acrylate groups, contain further ethylenically unsaturated groups, as in DE 103 31 456 A1 and WO 04/013 064 A2, or crosslinker mixtures, as described, for example, in DE 195 43 368 A1, DE 196 46 484 A1, WO 90/15 830 A1 and WO 02/032 962 A2.

Suitable crosslinkers b) are, in particular, N, N'-methylenebisacrylamide and N, N'-methylenebismethacrylamide, esters of unsaturated monocarboxylic or polycarboxylic acids of polyols, such as diacrylate or triacrylate, for example butanediol or ethylene glycol diacrylate or methacrylate, and trimethylolpropane triacrylate and allyl compounds, such as allyl (meth) acrylate, triallyl cyanurate, maleic acid diallyl esters, polyallyl esters, tetraallyloxyethane, triallylamine, tetraallylethylenediamine, allyl esters of phosphoric acid and vinylphosphonic acid derivatives, as described, for example, in EP 343 427 A2. Further suitable crosslinkers b) are pentaerythritol di-, pentaerythritol tri- and pentaerythritol tetraallyl ethers, polyethylene glycol diallyl ether, ethylene glycol diallyl ether, glycerol di- and glycerol triallyl ether, polyallyl ethers based on sorbitol, and ethoxylated variants thereof. Preferably used in the process according to the invention are di (meth) acrylates of polyethylene glycols, where the polyethylene glycol used has a molecular weight between 300 and 1000.

Further preferred crosslinkers b) are di- and triacrylates of 3- to 15-times ethoxylated glycerol, of 3 to 15-fold ethoxylated trimethylolpropane, of 3 to 15-fold ethoxylated trimethylolethane, in particular di- and triacrylates of 2 to 6 ethoxylated glycerol or trimethylolpropane, the 3-fold propoxylated glycerol or trimethylolpropane, and the 3-times mixed ethoxylated or propoxylated glycerol or trimethylolpropane, the 15-times ethoxylated glycerol or trimethylolpropane, and 40-times ethoxylated glycerol, trimethylolethane or trimethylolpropane.

Further preferred crosslinkers b) are the polyethoxylated and / or propoxylated glycerols esterified with acrylic acid or methacrylic acid to di- or triacrylates, as described, for example, in WO 03/104 301 A1. Particularly advantageous are di- and / or triacrylates of 3- to 10-fold ethoxylated glycerol. Very particular preference is given to diacrylates or triacrylates of 1 to 5 times ethoxylated and / or propoxylated glycerol. Most preferred are the triacrylates of 3 to 5 times ethoxylated and / or propoxylated glycerol. These are characterized by particularly low residual contents (typically below 10 ppm by weight) in the water-absorbing polymer and the aqueous extracts of the water-absorbing polymers produced therewith have an almost unchanged surface tension (typically at least 0.068 N / m) compared to water of the same temperature on.

The crosslinkers b) are preferably present in the solution or emulsion used in step (B) in an amount of from 1 to 8% by weight, preferably from 2 to 8% by weight, in each case based on the total solution or emulsion.

Examples of ethylenically unsaturated monomers c) copolymerizable with the monomers a) are acrylamide, methacrylamide, crotonamide, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminobutyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoneopentyl acrylate and dimethylaminoneopentyl methacrylate.

As water-soluble polymers d), polyvinyl alcohol, polyvinylpyrrolidone, starch, starch derivatives, polyglycols, formally wholly or partly formed from vinylamine monomers. built polymers such as partially or fully hydrolyzed polyvinylamide (so-called "polyvinylamine") or polyacrylic acids, preferably polyvinyl alcohol and starch, are used.

Further hydrophilic ethylenically unsaturated monomers a) which may be present in the solution or emulsion used in step (B) according to the invention are described, for example, in DE 199 41 423 A1, EP 686 650 A1, WO 01/45 758 A1 and US Pat WO 03/104 300 A1.

The polymerization is preferably carried out in the presence of customary polymerization regulators. Therefore, the solution or emulsion used in step (B) of the process according to the invention preferably contains at least one polymerization regulator. Suitable polymerization regulators are, for example, thio compounds, such as thioglycolic acid, mercapto alcohols, e.g. 2-mercaptoethanol, mercaptopropanol and mercaptobutanol, dodecylmercaptan, formic acid, ammonia and amines, eg. As ethanolamine, diethanolamine, triethanolamine, triethylamine, morpholine and piperidine.

The at least one polymerization regulator is preferably present in the solution or emulsion used according to the invention in an amount of from 10 to 60% by weight, preferably from 20 to 50% by weight, based in each case on the entire solution or emulsion.

The solution or emulsion used in step (B) of the process according to the invention preferably contains at least one polymerization initiator. As polymerization initiators it is possible to use all compounds which decompose into free radicals under the polymerization conditions, for example peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and the so-called redox initiators. Preference is given to the use of water-soluble initiators. In some cases, it is advantageous to use mixtures of different polymerization initiators, for. B. mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate. Mixtures of hydrogen peroxide and sodium peroxodisulfate can be used in any proportion. 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 perohexanoate, tert-butyl perisobutyrate, tert-butyl per 2-ethylhexanoate, tert-butyl perisononanoate, tert Butyl permaleate, tert-butyl perbenzoate, tert-butyl per 3,5,5-tri- methylhexanoat and tert-Amylperneodekanoat. Other suitable polymerization initiators are azo initiators, e.g. 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N) dimethylene) isobutyramidine dihydrochloride, 2- (carbamoylazo) isobutyronitrile and 4,4'-azobis (4-cyanovaleric acid).

The redox initiators contain as oxidizing component at least one of the abovementioned per compounds and a reducing component, for example ascorbic acid, glucose, sorbose, ammonium or alkali metal hydrogen sulfite, sulfite, thiosulfate, hyposulfite, pyrosulfite or sulfide, metal salts such as iron -ll-ions or silver ions or sodium hydroxymethylsulfoxylate. As reducing component of the redox initiator, ascorbic acid or sodium pyrosulfite is preferably used. Based on the amount of monomers used in the polymerization is used 1 ^■ 10 ^"5 to 1 mol% of the reducing component of the redox initiator and 1 ^■ 10 ^{" 5} to 5 mol% of the oxidizing component. Instead of the oxidizing component or in addition one can also use one or more water-soluble azo initiators.

Preference is given to using a redox initiator comprising hydrogen peroxide, sodium peroxodisulfate and ascorbic acid. For example, these components are used in the concentrations 1 ^■ 10 ^"2 mol% hydrogen peroxide, 0.084 mol% sodium peroxodisulfate and 2.5 ^■ ^{10" 3} mol% ascorbic acid based on the monomers employed.

In a further preferred embodiment, as an initiator at least one water-soluble azo compound, particularly preferably 2,2'-azobis (2-amidinopropane) dihydro chloride, CAS Number 2997-92-4, commercially available as V50 ^® from Wako used.

The monomer solution or emulsion used in step (B) of the process of the invention may contain the initiator dissolved or dispersed.

The initiator is preferably present in the solution or emulsion used according to the invention in an amount of from 0.5 to 10% by weight, preferably from 1 to 6% by weight, in each case based on the total solution or emulsion.

The solution or emulsion used in step (B) of the process according to the invention preferably contains at least one surfactant selected from nonionic, anionic, cationic and amphoteric surfactants. Nonionic surfactants are preferably used, particularly preferably ethoxylated fatty alcohols, very particularly preferably C 16 / C 18 fatty alcohols alkoxylated with 80 units of ethylene oxide, for example commercially available as Lutensol AT 80® from BASF Aktiengesellschaft. The surfactants are present in the solution or emulsion used in the process according to the invention preferably in an amount of 1 to 10 wt .-%, preferably 2 to 8 wt .-%, each based on the total solution or emulsion.

The solution or emulsion used in step (B) of the present process according to the invention may in a further preferred embodiment for avoiding or reducing unpleasant odors, for example after contact of the formed superabsorbent polymer with body fluids, at least one odor inhibitor, for example a keto acid, organic acids, urease inhibitors or mixtures thereof.

Keto acids (this is a common shorthand of the systematically more correct term "ketocarboxylic acids") are a subset of the oxocarboxylic acids, namely the carboxylic acids which contain a ketone group in addition to a carboxy group.

The keto acid which may optionally be present in the superabsorbent polymer which can be used according to the invention has the general formula R ⁵ -C (O) -R ⁶ -COOH, where R ⁶ may be omitted and preferably also omitted. Thus, the composition according to the invention preferably contains superabsorbent and at least one keto acid of the general formula R ⁵ -CO-COOH, ie an alpha-keto acid or 2-oxo-carboxylic acid.

R ⁵ is a linear, branched or cyclic organic radical which is optionally substituted. R ⁵ is for example a d- to C ₃ -alkyl radical, preferably a C ₂ - to C ₀ - alkyl group, particularly preferably a C ₃ - to C ₄ -alkyl radical. Examples of C 1 to C 10 -alkyl radicals are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-heptyl , Isoheptyl, n-octyl, isooctyl, n-nonyl, isononyl, n-decyl and isodecyl. Very particularly preferred alkyl radicals are n-propyl and n-butyl. This alkyl radical is optionally substituted with one or more functional groups, in particular one or more hydroxy and / or carboxy groups.

R ⁶ , if present, is an organic group having two attachment sites, for example a - (CH ₂ ) _n - group, where n is generally a number from 1 to 4. The group may be linear, branched or cyclic and optionally substituted.

In a particularly preferred form, the keto acid is 2-oxo-L-gulonic acid (the L-enantiomer of 2-oxo-3,4,5,6-tetrahydroxihexanoic acid) and / or 2-oxo-glutaric acid (2-oxo-pentane). 1, 5-diacid). The amount of the keto acid in the superabsorbent based on the amount of superabsorbent is generally at least 0.005 wt%, preferably at least 0.01 wt%, more preferably at least 0.1 wt%, and most preferably Form at least 0.5 wt .-% and generally at most 15 wt .-%, preferably at most 12 wt .-% and in a particularly preferred form at most 10 wt .-%. For example, this amount is 1 wt .-%, 2 wt .-%, 3 wt .-%, 4 wt .-%, 5 wt .-%, 6 wt .-%, 7 wt .-%, 8 wt. % or 9 wt .-%, each based on the amount of superabsorbent.

The solution or emulsion used according to the invention in step (B) preferably comprises at least one solvent selected from the group consisting of alcohols, for example methanol, ethanol, n-propanol, isopropanol, butanols and water, preferably water. The amount of solvent is determined so that the solution has a suitable viscosity for the impregnation. The solvent is present in the solution or emulsion used according to the invention preferably in an amount of from 1 to 10% by weight, preferably from 2 to 8% by weight, in each case based on the total solution or emulsion.

The sum of all components present in the solution or emulsion used in step (B) of the process according to the invention is 100% by weight.

In a very particularly preferred embodiment, in step (B) of the process according to the invention a solution is applied to the carrier material which contains the following components:

i) from 10 to 60% by weight, preferably from 20 to 55% by weight, of at least one unsaturated monocarboxylic acid, for example acrylic acid and / or methacrylic acid, ii) from 1 to 10% by weight, preferably from 2 to 8% by weight at least one solvent, for example water, iii) from 2 to 25% by weight, preferably from 8 to 20% by weight of at least one neutralized unsaturated monocarboxylic acid, for example an alkali metal salt of acrylic acid and / or methacrylic acid, preferably a sodium salt, iv) from 1 to 8 % By weight, preferably from 2 to 8% by weight of at least one crosslinking agent, for example polyethylene glycol diacrylate (PEGDA), v) from 1 to 10% by weight, preferably from 2 to 8% by weight of at least one surfactant, for example a nonionic surfactant, vi) 10 to 60 wt .-%, preferably 20 to 50 wt .-% of at least one polymerization, for example triethanolamine and vii) 0.5 to 10 wt .-%, preferably 1 to 6 wt .-% of at least one polymerization initiator, for example V50®,

in each case based on the total solution or emulsion, wherein the sum of all components gives 100 wt .-%.

The solution or emulsion used in step (B) of the process according to the invention is prepared in a preferred embodiment by mixing the individual components, optionally with cooling, for example at 0 to 20 ^° C., preferably at 5 to 20 ^° C.

In a preferred embodiment of the method according to the invention, the impregnation is carried out by spraying or soaking. It is also possible according to the invention that a combination of spraying and impregnating is carried out.

In the context of the present invention, drinks means that the carrier material is completely immersed in a solution or emulsion of the corresponding monomers and other components. The carrier material is generally left in the solution or emulsion until a sufficient amount of solution or emulsion is present in the carrier material. The time depends on the concentration and viscosity of the solution or emulsion used.

In a preferred embodiment, after soaking, excess monomer solution or emulsion is removed from the carrier material. For this, in a preferred embodiment, this is placed on a suitable device, for example on a grid, so that excess solution or emulsion not absorbed by the carrier material can drip off. The duration of this dripping is generally determined by the duration of impregnation of the carrier material in the solution. The optionally to be carried out dripping is terminated when substantially no solution or emulsion drips out of the carrier material. In a further preferred embodiment, the amount of excess liquid is removed by mechanical stress, for example pressing, preferably with a calender. By this treatment, the homogeneity of the distribution of absorbed liquid is improved. Part of the liquid can also be removed by shaking or centrifuging, or by underpressure or overpressure. The impregnation can be carried out at any customary temperature at which the monomers present in the solution or emulsion do not polymerize, for example at 0 to 50 ^° C., preferably at room temperature.

The impregnation in step (B) of the process according to the invention can be carried out in a further preferred form by spraying the support material with a solution of monomers from which the superabsorbent polymer is composed.

In this preferred embodiment, a sprayable mixture containing the monomers and, optionally, the additives listed above are prepared. The order of addition of these substances is generally arbitrary, but for safety reasons, it is preferred to add the initiator last.

The amounts of the individual mixture components are given above and are generally chosen so that the viscosity of the sprayable mixture measured in the viscometer profile is 20 to 400 centipoise, more preferably 30 to 150 centipoise, and most preferably 40 to 100 centipoise. The viscosity of the sprayable mixture is influenced by a variety of factors, including the degree of neutralization of the at least one superabsorbent monomer and the concentration of the monomers employed.

If the impregnation by spraying, in a preferred embodiment, the solution or emulsion described above by further solvent, preferably the same, which is already present, more preferably water, so diluted that a solids content of 30 to 60%, preferably 40 to 55 % is set.

After the preparation of the sprayable mixture, this is sprayed onto the submitted carrier material. The term "spraying" or "spraying" is intended to encompass all suitable means for the production and transport of liquid drops. The spraying can be done by means of a conventional spraying device. The spraying can take place as airless spraying, air-assisted airless spraying or as compressed air spraying. The air may be wholly or partially replaced by at least one inert gas, such as nitrogen, argon or helium, to promote the removal of oxygen from the sprayable mixture during spraying. The sprayable mixture is sprayed in amounts of from 20 to 400 grams per square meter (g / m ² ), preferably from 40 to 300 g / m ^2, and most preferably from 60 to 150 g / m ² of superabsorbent polymer resulting from the monomers. The spray device should be adjusted so that the droplet size of the spray takes into account factors such as the desired particle size of the SAP particles on the finished product. The loading by soaking can be adjusted according to the intended application of the composite. A maximum load of 99% by volume is possible.

In the embodiment in which the impregnation is carried out by spraying, it is preferable, after application of the monomer solution, to spray at least one solution of di- or polyvalent cations, the cations being able to react with the acid groups of the polymer to form complexes.

Examples of divalent or polyvalent cations are polymers which are formally wholly or partially composed of vinylamine monomers, such as partially or completely hydrolyzed polyvinylamide, whose amine groups are always partially protonated to ammonium groups, even at very high pH values, or metal cations such as 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 ^{4 +} , 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⁺ . The metal cations can be used both alone and in a mixture with each other. Of the cited metal cations, all metal salts are suitable which have sufficient solubility in the solvent to be used. Particularly suitable are metal salts with weakly complexing anions such as chloride, nitrate and sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate and carboxylate, such as acetate and lactate. In a particularly preferred form, aluminum sulfate is used. As solvents for the metal salts, water, alcohols, dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and mixtures of these components can be used. Particularly preferred are water and water / alcohol mixtures such as water / methanol, water / 1, 2-propanediol and water / 1, 3-propanediol.

In the metal salt solution described above, the concentration of the at least one metal salt is generally from 0.001 to 10% by weight, preferably from 0.01 to 5% by weight, particularly preferably from 0.05 to 1% by weight, based in each case on the entire metal salt solution.

The treatment of the spray-impregnated support material with a solution of a di- or polyvalent cation may also be accomplished by spraying a corresponding solution onto the support material in the same manner as applying the monomer solution. By the optional method step of spraying with a metal salt solution described above, in a preferred embodiment, 0.1 to 10 wt .-%, particularly preferably 0.5 to 8 wt .-%, each based on the finished composite material, metal salt applied to the carrier material ,

In the process according to the invention, in a preferred embodiment, by impregnating with the solution, so many monomers are brought onto and into the carrier material that not all pores of the melamine-formaldehyde foam are completely filled with superabsorber after the polymerization. A degree of filling which enables a corresponding swelling of the superabsorber is preferred according to the invention. In a preferred embodiment, the amount of monomers is such that the weight ratio of the amounts of superabsorbent polymer to support material in a preferred embodiment is 0.01: 1.0 to 5: 1.0, more preferably 0.1: 2.0, for example 1 : 1, 1: 2, 1: 4 or 1: 8.

Especially the foams produced from the aminoplast resins used have an ideal pore size and distribution in order to absorb the superabsorbent polymer in these pores in the interior or on the surface of the carrier material. The adhesion of the superabsorbent polymer to the carrier material is also high enough according to the invention, so that the composite material produced has a high stability during use. In a preferred embodiment, the pore size in the foam is 10 to 1000 microns, more preferably 50 to 500 microns.

Step (C):

After impregnation of the at least one support material from step (A) with a solution or emulsion of monomers from which the at least one superabsorbent polymer is constructed according to step (B), the polymerization of the monomers from step (C) takes place in step (C). B) on or in the carrier material. According to the invention, polymerization also means curing of the polymeric compounds or the like.

The polymerization of the present monomers does not take place in step (B) but only in step (C) of the process according to the invention.

For this purpose, the impregnated support material in step (C) of the process according to the invention is subjected to conditions in which the superabsorbent polymer forming Polymerize monomers. Depending on the types of initiators present in the solution or emulsion used in step (B), these conditions include, for example, the action of heat, ultraviolet rays, electron beams or their combination on the impregnated support material. Furthermore, static or continuous conditions may act on the composite, for example, by passing the composite on a conveyor belt irradiation or heating sections.

In thermal polymerization, the reaction device is not particularly limited. In the case of discontinuous polymerizations, the sprayed support materials can be polymerized in an oven in air or in an inert atmosphere or optionally also in vacuo. For example, in the case of a continuous process, the substrate passes through a dryer such as an infrared dryer, a through-air dryer or the like. The polymerization temperature varies depending on the thickness of the carrier material, the monomer concentration and the kind and amount of the thermal initiator used in the sprayable mixture. The polymerization is usually carried out in a temperature range from 20 to 150 ^° C., preferably from 40 to 100 ^° C. The polymerization is generally carried out at a pressure of from 10 to 500 mbar, preferably from 20 to 300 mbar, particularly preferably from 50 to 200 mbar. The polymerization is carried out in a further preferred embodiment in an inert atmosphere, for example in a nitrogen or inert gas atmosphere, for example in helium or argon. The polymerization time depends on the polymerization temperature, but is typically in the range of a few seconds to two hours, and preferably in the range of a few seconds to 10 minutes. After completion of the polymerization, the support material can be dried to the desired moisture content.

UV curing of the solution impregnated support materials can be accomplished using a conventional UV lamp. Irradiation conditions, such as radiation intensity and time, depend, for example, on the type of support material used, the amount of monomer applied to the substrate, and the like. In general, however, the irradiation is carried out using a UV lamp with an intensity in the range of 100 to 700 watts per square inch, preferably in the range of 400 to 600 watts per square inch, with a distance between UV lamp and substrate between 2 to 30 cm, in a period of 0.1 seconds to 10 minutes. The irradiation of the composite material with ultraviolet rays may be carried out in vacuo, in the presence of an inorganic gas such as nitrogen, argon, helium and the like, or in air. The irradiation temperature is not critical, the irradiation of the im- impregnated support material can be carried out with satisfactory results even at room temperature.

The polymerization can be carried out in a preferred embodiment by using microwaves. This procedure is advantageous because with microwaves a good and uniform heat input into the foam can be realized, prevents the convection and thermally insulated. Methods for polymerizing by means of microwaves are known to the person skilled in the art. In a preferred embodiment, the optional tempering is effected by microwave radiation. In principle, microwaves in the frequency range from 0.2 GHz to 100 GHz can be used for this dielectric radiation. For industrial practice frequencies of 0.915, 2.45 and 5.8 GHz are available, with 2.45 GHz being particularly preferred.

Radiation source for dielectric radiation is the magnetron, which can be irradiated simultaneously with several magnetrons. Care must be taken to ensure that the field distribution during irradiation is as homogeneous as possible in order to obtain a uniform heating.

For electron beam curing, for example, a commercially available elec- is ronen beam acceleration device like the Electrocurtain ^® CB 175 (Energy Science, Inc., Wilmington, USA). In the range of 150 to 300 kilovolt operating accelerometers are preferred. The beam current, typically in the range of 1 to 10 milliamperes, of such devices can be adjusted to the desired dose of ionizing radiation. The particular dose of ionizing radiation will vary somewhat depending on such factors as the presence or absence of crosslinking monomers, the desired degree of polymerization of the polymer, the degree of crosslinking desired, and the like. In general, it is desirable to irradiate the coated substrate with doses of about 1 to 16 megarads, and preferably 2 to 18 megarads. Especially in lower dose applications, it is desirable to free the sprayable mixture of oxygen, eg, by carrying out the irradiation under inert conditions, for example under nitrogen. The maximum dose would be the dose at which degradation of the carrier material begins.

After irradiation, the support material can be freed from the solvent, for example water, by drying in a circulating air oven, with infrared lamps and the like. The present invention also relates to a composite material comprising at least one superabsorbent polymer and at least one elastic foamed aminoplast resin as a carrier material, wherein the ratio of superabsorbent polymer (dry) to carrier material is 1, 0-1000 g of superabsorbent polymer (dry) / liter of carrier material. Since the composite material according to the invention is obtained by polymerizing corresponding monomers in the support material, the proportion of superabsorbent polymer is at relatively high values of 1, 0-1000 g SAP (dry) / liter of support material.

In a preferred embodiment, the composite material according to the invention can be produced by the method according to the invention.

With respect to the superabsorbent polymers and the foamed elastic aminoplast resins, what has been said with regard to the process according to the invention applies.

In a preferred embodiment of the composite material of the invention, the at least one superabsorbent polymer is a homo- or copolymer containing unsaturated mono- or dicarboxylic acids.

In a particularly preferred embodiment, the superabsorbent polymer is composed of

at least one unsaturated monocarboxylic acid, for example acrylic acid and / or methacrylic acid, - at least one neutralized unsaturated monocarboxylic acid, for example an alkali metal salt of acrylic acid and / or methacrylic acid, preferably a sodium salt, at least one crosslinker, for example polyethylene glycol diacrylate (PEGDA) and at least one polymerization regulator, for example triethanolamine.

In a further preferred embodiment, the aminoplast elastic resin is a melamine / formaldehyde resin whose molar ratio of melamine to formaldehyde is preferably between 1: 1, 0 and 1: 1, 9.

In the composite material according to the invention, the weight ratio of superabsorbent polymer to support material in a preferred embodiment is 0.01: 1, 0 to 5: 1, 0, more preferably 0.1: 2.0, for example 1: 1, 1: 2, 1 : 4 or 1: 8. The composite material according to the invention is capable of absorbing large quantities of liquid. Since the foam is at most 99% by volume of air, it can thus absorb about 10,000% by weight of the dry weight of liquid. Furthermore, the composite material according to the invention is able, even under pressure, to hold the absorbed liquid so that it can not escape from the composite material again. The carrier material present in the composite material according to the invention makes it possible for liquid, which impinges on the composite material in a small area, to be distributed through the carrier material over the entire composite material. This fact ensures that, even if the liquid to be absorbed impinges only on a small area of the composite material, the absorption force of the entire superabsorbent material present in the composite material can be utilized. Further advantages include, for example, increased mechanical stability of the swollen superabsorbent material and the possibility of producing elastic superabsorbent materials. Since, in a preferred embodiment, the pores of the foam are only partially filled with superabsorbent material, the surface area of the superabsorbent material is increased, resulting in faster fluid uptake and swelling.

The present invention also relates to hygiene products, for example diapers, sanitary napkins, incontinence products, sealing materials, for example on pipes or tunnels, insulating materials, drying agents, water reservoirs, packaging and artificial plant substrates containing the composite material according to the invention.

The present invention also relates to the use of the composite material according to the invention in the area of hygiene, for example in baby diapers, incontinence products, sanitary napkins, in agriculture, for example as a water reservoir, for irrigation, for mixing with soil, in the automotive sector, for example in the seat backrests, in the steering wheel, in the furniture sector, for example in upholstered furniture, chairs, as a sealing material, for example in the construction industry, as artificial plant substrates or in the cosmetics sector, for example in cosmetic sponges. Examples:

Measurement Methods:

CRC

Centrifuge Retention Capacity ("CRC") corresponds to the amount of fluid retained after centrifugation, and the CRC value is determined as follows: A circular sample of the 5 cm diameter sheet is cut into two equal halves and one half into one optionally tea bags (size 6 cm ^* 8.5 cm) and the weight of the sample prior to insertion into the tea bag is recorded;. the teabag is sealed and soaked for 20 minutes in 0.9% sodium chloride solution the teabag is three minutes The centrifuged tea bag is weighed and the CRC value in g / m ^{2 is} calculated according to the following formula:

CRC = (weight of tea bag - sample weight dry - blank value) / A,

wherein the blank value represents the average wet weight determined from two measurements of an empty tea bag after centrifuging and A equals the sample area in m ² .

FSC

Free Swell Capacity ("FSC") is the amount of fluid retained after dripping that is equivalent to the CRC test, except that centrifugation is omitted, the FSC value is determined as follows and is shown in the following tables: A circular sample of the 5 cm diameter sheet is cut into two equal halves and one half is placed in a tea bag (6 cm ^* 8.5 cm) and the weight of the sample is noted prior to insertion into the tea bag; the teabag is sealed and soaked in a 0.9% sodium chloride solution for 20 minutes, then the teabag is taken out of the sodium chloride solution and hung in the air for 10 minutes, the tea bag is then weighed and the FSC in g / m ^{2 is} calculated according to the following formula:

FSC = (weight of tea bag - sample weight dry - blank value) / A, wherein the blank value represents the average wet weight of an empty teabag after suspension as determined from two measurements, and A equals the sample area in m ² .

Example 1: Preparation of the monomer solution

An aqueous solution which can be used according to the invention and contains the monomers which form the superabsorbent polymer is prepared, see Table 1.

Table 1 :

Comments: PEGDA: Polyethylene glycol diacrylate, Mw = about 400 g / mol V 50®: water-soluble initiator of Wako Lutensol AT 80® nonionic surfactant, Ci ₆ / Ci ₈ -fatty alcohols, ethoxylated with 80 units of ethylene oxide

Components 1 to 5 are mixed with stirring and cooling. Subsequently, triethanolamine is added dropwise, the temperature does not exceed 15 ⁰ C. It is then inertized for 25 minutes with CO ₂ , V 50® is added and it is again inertized with stirring for 5 minutes.

Example 2: Preparation of a composite material according to the invention by impregnation

A foam sheet of 20 cm × 15 cm × 1 cm, which consists of a formaldehyde / melamine resin with a formaldehyde: melamine ratio of 3: 1, is introduced into the monomer solution from Example 1 until the sheet is completely covered with Filled liquid. Thereafter, the thus prepared plate is placed on a mesh screen for 10 minutes to drain. In this case, by slightly pressing the excess liquid removed from the substrate a little faster. The mixture is then dried in a vacuum drying oven at 80 ⁰ C and a nitrogen flow of 150 l / h in a vacuum of about 100 mbar and polymerized. The results of two experiments A and B, as well as the blank tests are listed in Table 2 below. A and B in Table 2 differ in the amount of monomer solution.

Table 2:

Example 3

Example 3 corresponds to Example 2, with the difference that the fully saturated plate lying on the grid screen is expressed with a rubber roller. A, B and C in Table 3 differ in the amount of carrier material and / or monomer solution. The results are shown in Table 3.

Example 4: Preparation of a composite material according to the invention by spraying

In this example, a composite material according to the invention is prepared in which a sheet of formaldehyde / melamine resin according to Example 2 is sprayed with the solution from Example 1. In contrast to Example 1, the solution used has a solids content of 50%, which is achieved by dilution with 360 g of deionized water.

A sheet of a formaldehyde / melamine resin of about 20 x 15 cm (10 mm thick) is sprayed with both sides of the monomer solution (glass nozzle). The mixture is then dried in a vacuum oven at 80 ^° C. in a nitrogen stream of 150 l / h in a vacuum of 100 mbar overnight and polymerized. A - D in Table 4 differ by the ratio of the amount of superabsorbent to carrier material. The results are summarized in Table 4.

Example 5

Example 5 differs from Example 4 in that after spraying the plate on both sides with the monomer solution from Example 1, an aluminum sulfate solution is sprayed on. A - 1 in Table 5 differ by the ratio of the amount of superabsorbent to carrier material and / or by the amount of aluminum sulfate. The results are shown in Table 5.

Claims

claims

A composite material comprising at least one superabsorbent polymer and at least one elastic foamed aminoplast resin as support material, characterized in that the ratio of superabsorbent polymer (dry) to support material is 1, 0-1000 g superabsorbent polymer (dry) / liter of support material.

2. A composite material according to claim 1, characterized in that the at least one superabsorbent polymer is a homo- or copolymer containing unsaturated mono- or dicarboxylic acids.

3. Composite material according to claim 1 or 2, characterized in that the superabsorbent polymer is composed of - at least one unsaturated monocarboxylic acid, at least one neutralized unsaturated monocarboxylic acid, at least one crosslinker and at least one polymerization regulator.

4. Composite material according to one of claims 1 to 3, characterized in that the elastic foamed aminoplast resin is a foamed MeI- amine / formaldehyde resin, the molar ratio of melamine to formaldehyde preferably between 1: 1, 0 and 1: 1, 9.

5. Hygiene products, sealing materials, insulating materials, drying agents, water reservoirs, packaging and artificial plant substrates, containing a composite material according to one of claims 1 to 4.

6. Use of a composite material according to one of claims 1 to 4 in Hygie- nebereich, in agriculture, in the automotive sector, in the furniture sector, as a sealing material or in the cosmetics sector.

7. A process for producing a composite material comprising at least one superabsorbent polymer and at least one elastic foamed amino resin as support material comprising the steps:

(A) providing the at least one carrier material, (B) impregnating the at least one support material from step (A) with a solution or emulsion of monomers of which the at least one superabsorbent polymer is made up, and

(C) polymerizing the monomers from step (B) on or in the support material.

8. The method according to claim 7, characterized in that the at least one carrier material is a melamine-formaldehyde resin.

9. The method according to claim 7 or 8, characterized in that the at least one superabsorbent polymer is a homo- or copolymer containing unsaturated mono- or dicarboxylic acids.

10. The method according to any one of claims 7 to 9, characterized in that the impregnation in step (B) is carried out by soaking or spraying.

1 1. A method according to claim 10, characterized in that after impregnation, excess monomer solution or emulsion is removed from the carrier material.