EP2061819A1

EP2061819A1 - Aqueous dispersions of cross-linked, tertiary ester groups containing emulsion polymerisates and water-absorbent materials on a carrier material made thereof

Info

Publication number: EP2061819A1
Application number: EP07802498A
Authority: EP
Inventors: Marc Bothe; Hermann Seyffer; Mirjam Herrlich-Loos; Robert Heger; Matthias Weismantel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2006-08-17
Filing date: 2007-08-06
Publication date: 2009-05-27
Also published as: US20100189994A1; CN101506256A; WO2008019966A1

Abstract

Aqueous dispersions of cross-linked, tertiary ester groups containing emulsion polymerisates, (a) at least 50 wt.% of an ester, derived of a tertiary alcohol and a ethylenic unsaturated C3- to C5- carboxylic acid, (b) 0,001 to 5,0 wt.% of at least one compound, comprising at least two ethylenic unsaturated double compounds, and (c) 0 to 49,999 wt.% of at least one other monoethylenic unsaturated compound copolymerized and having an average particle size of 1000 nm at most, and water absorbent materials, obtainable by layering of a carrier material with said aqueous dispersion of a cross-linked, tertiary ester groups containing emulsion polymerisate, drying and heating of the thus treated carrier material to a temperature of at least 1400C while producing carboxyl groups from the tertiary ester groups of the emulsion polymerisate and at least partial neutralization of the carboxyl groups and the use of the water-absorbing materials as absorption means for water and aqueous liquids.

Description

Aqueous dispersions of crosslinked, tertiary ester group-containing emulsion polymers and water-absorbing materials prepared therefrom on a support material

description

The invention relates to aqueous dispersions of crosslinked, tertiary ester group-containing emulsion polymers, water-absorbing materials of a carrier material and a water-absorbing polymer and the use of water-absorbing materials for receiving body fluids or other aqueous liquids.

Water-absorbent or water-swellable polymers, for example, absorb at least 25%, preferably at least 100%, of their own weight in water. Known water-absorbing polymers, which are also referred to as superabsorbent and absorb more than 10 times their weight in water, are, for example, crosslinked polyacrylic acids, graft copolymers of ethylenically unsaturated carboxylic acids on polysaccharides, crosslinked cellulose or starch ethers and crosslinked polyalkylene oxides. Water-absorbing polymers are e.g. in diapers, tampons, tissue papers, dressings, sanitary papers, cleaning wipes and packaging papers.

For example, EP-A-0 437 816 discloses a superabsorbent wet-laid nonwoven material obtained as follows: mixing particulate superabsorbent (particle size 0.5 to 450 μm) with a liquid to form a slurry, mixing the slurry thus obtained with fibers, filtering the mixture of superabsorbent and fibers and then drying to obtain a superabsorbent wet-laid nonwoven material. The materials thus obtained are i.a. in diapers, incontinence articles, packaging papers for food and dressing materials such as patches.

From EP-B-1 068 392 an improved wet process for producing an absorbent structure is known. Accordingly, in a device for web formation by the wet process, a fiber suspension is processed, which additionally contains water-swellable, water-insoluble superabsorbent particles. A wetted wet-web containing superabsorbent particles is formed, deprived of water, and then conveyed to the dryer section of the apparatus. It is crucial here that the contact between superabsorbent and suspension up to the fleece inlet into the dryer section is at most 45 seconds, whereby the superabsorbent does not receive sufficient time for swelling.

US 5,997,690 and US 6,290,813 B1 disclose a process for the production of highly absorbent wet laid nonwoven material, wherein first a slurry of water-swellable, water-insoluble superabsorbent particles with fibers is produced. The superabsorbent particles have a particle size of less than 250 microns prior to addition to the aqueous slurry of fibers. This slurry is then added to a saline solution. Thereafter, a wet web is formed, which is washed with water and then dried. The wet laid nonwoven materials thus obtained have a residual salt content of less than 40% when dry.

US-A-2002/0060013 discloses a process for the production of wet laid nonwoven materials containing at least 1% by weight of an absorbent polymer having a thermo-reversible liquid holding capacity.

From US-A-2003/0014038 superabsorbent articles are known which contain a core with swellable branched superabsorbent particles. The articles disclosed in this document can be supplemented with effective amounts of an antibiotic or antibacterial agent so that the end products can be used in the medical field.

From the earlier application PCT / EP2006 / 062346 a process for the production of paper, paperboard and cardboard is known, wherein a fiber suspension, e.g. Contains 0.1 to 20 wt .-% water-swellable polymers, ground and then dewatered on a sieve with formation of leaves. The water-swellable polymers containing materials are used for example as tissue papers, sanitary and sanitary papers, packaging papers or for the production of multi-layer papers.

In addition, DE-A-1 811 593 discloses reversibly water-vapor-absorbing planar structures which are obtainable by coating a flat structure (non-woven fabric or fabric) with an aqueous dispersion of a copolymer which comprises polymerized tert-butyl acrylate which has been coated The structure is then dried and heated to a temperature of, for example, 100 to 140 ^° C., whereby isobutene is eliminated from the polymerized tert-butyl acrylate and the coating is foamed up.

It is an object of the present invention to provide novel substances from which e.g. water-absorbing materials are available.

The object is achieved according to the invention with aqueous dispersions of crosslinked, tertiary ester group-containing emulsion polymers when the emulsion polymers

(a) at least 50% by weight of an ester derived from a tertiary alcohol and an ethylenically unsaturated C3 to C5 carboxylic acid, (B) 0.001 to 5.0 wt .-% of at least one compound having at least two ethylenically unsaturated double bonds, and

(c) 0 to 49.999% by weight of at least one other monoethylenically unsaturated compound

contained in copolymerized form and have an average particle size of at most 1000 nm.

Preference is given to crosslinked emulsion polymers which

(a) at least 90% by weight of a tert-butyl ester of an ethylenically unsaturated C3 to C6 carboxylic acid,

(b) 0.01 to 2.0% by weight of at least one compound having at least two ethylenically unsaturated double bonds, and (c) 0 to 49.99% by weight of at least one other monoethylenically unsaturated compound

contained in copolymerized form and have an average particle size of less than 500 nm.

Particular preference is given to crosslinked emulsion polymers which

(A) 98.0 to 99.99 wt .-% of at least one tert-butyl ester of an ethylenically unsaturated C3 to Cδ carboxylic acid and (b) 0.01 to 2.0 wt .-% of at least one compound which at least has two ethylenically unsaturated double bonds,

contained in copolymerized form and have an average particle size of 30 to 400 nm.

Suitable monomers of group (a) are preferably esters which are derived from tert-butanol or tert. -Amylalkohol (2-methylbutan-2-ol) and ethylenically unsaturated C3- to Cδ-carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, vinylacetic acid, vinyllactic acid and ethacylic acid. In the esterification, for example, use a single ethylenically unsaturated carboxylic acid or two or more of such acids. Mixtures of tertiary esters are then obtained which, like the pure esters, can be used in the polymerization as component (a). Tert-butyl acrylate is also obtainable, for example, by addition of isobutene to acrylic acid. From this group of monomers tert-butyl acrylate is preferably used.

The monomers of group (a) are contained in the emulsion polymers in an amount of at least 50 wt .-%, preferably at least 90 wt .-%. The E Emulsion polymers usually contain 98.0 to 99.9 wt .-% of at least one monomer of group (a).

Suitable monomers of group (b) are compounds which have at least two ethylenically unsaturated double bonds. This group of monomers are so-called crosslinkers, which are usually used in the production of water-absorbing polymers (superabsorbents), cf. EP-A-0 858 478, page 4, line 30 to page 5, line 43 and EP-A-0 547 847, EP-A-0 559 476, EP-A-632 068, WO-A-93/21237, WO-A-03 / No. 104299, WO-A-03/104300, WO-A-03/104301 and mixtures of crosslinking agents which are known, for example, from DE-A-195 43 368, DE-A-196 46 484, WO-A-90/15830 and WO -A-02/32962 are known.

Examples of crosslinkers are triallylamine, pentaerythritol triallyl ether, methylenebisacrylamide, N, N'-divinylethyleneurea, allyl ethers containing at least two allyl groups or vinyl ethers of polyhydric alcohols having at least two vinyl groups, such as, for example, Sorbitol, 1, 2-ethanediol, 1, 4-butanediol, trimethylolpropane, glycerol, diethylene glycol and of sugars such as sucrose, glucose, mannose, completely with acrylic acid or methacrylic acid diesterified alcohols having 2 to 4 carbon atoms such as ethylene glycol dimethacrylate , Ethylene glycol diacrylate, butanediol dimethacrylate, butanediol diacrylate, diacrylates or dimethacrylates of polyethylene glycols having molecular weights of 100 to 600, ethoxylated trimethylenepropane triacrylates or ethoxylated trimethylene propane trimethacrylates, 2,2-bis (hydroxymethyl) butanol trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate and triallylmethylammonium chloride. The emulsion polymers preferably comprise allyl methacrylate, butanediol-1,4-diacrylate, divinylbenzene or mixtures thereof in copolymerized form.

The amounts of copolymerized crosslinker contained in the emulsion polymers are from 0.001 to 5.0 wt .-%, preferably 0.01 to 2.0 wt .-%.

Particular preference is given to emulsion polymers which comprise, as polymer of group (a), tert-butyl acrylate and / or tert-butyl methacrylate and, as monomer of group (b), allyl methacrylate, butanediol diacrylate, divinylbenzene or mixtures thereof.

The crosslinked emulsion polymers may optionally be used as monomers of

Group (c) in copolymerized form at least one other monoethylenically unsaturated monomer to modify the properties. Examples of such monomers are esters of primary or secondary monohydric alcohols having 1 to 22 C atoms and ethylenically unsaturated C3 to Cs carboxylic acids (for example methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, dimethyl maleate, diethyl maleate and itaconic acid dimethyl ester), styrene, α-methylstyrene, vinylsulfonic acid, vinylphosphonic acid, sulfopropyl acrylate, sulfoethyl methacrylate, 2-acrylamidomethylpropionic acid, styrenesulfonic acid, alkali metal and ammonium salts of the abovementioned acids, acrylamide, methacrylamide, N-vinylformamide, acrylonitrile, methacrylonitrile, N, N-dialkylaminoalkyl (meth) acrylates (for example dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate and also the salts of said basic monomers with mineral acids or carboxylic acids and the basic monomers quaternized with alkyl halides or with dimethyl sulfate) and dialkylaminoalkyl (meth) acrylamides such as dimethylaminoethylacrylamide.

The crosslinked emulsion polymers contain the monomers of group (c) copolymerized in an amount of 0 to 49.999 wt .-%. If monomers of group (c) are contained in the emulsion polymers, their proportion is usually up to 8 wt .-%.

The implementation of free-radically initiated emulsion polymerizations of ethylenically unsaturated monomers in an aqueous medium has been described in the literature and is therefore sufficiently known to the person skilled in the art [cf. for this emulsion polymerization in Encyclopedia of Polymer Science and Engineering, Vol. 8, pages 659 et seq. (1987); D. C. Blackley, in High Polymer Latices, Vol. 1, pp. 35 et seq. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, pages 246 et seq. (1972); D. Diederich, Chemistry in Our Time 24, pages 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and dispersions of synthetic high polymers, F. Hölscher, Springer-Verlag, Berlin (1969)]. The free-radically induced aqueous emulsion polymerization reactions usually take place in such a way that the ethylenically unsaturated monomers are dispersed in the aqueous medium in the form of monomer droplets with the concomitant use of dispersing agents and polymerized by means of a free-radical polymerization initiator.

In the preparation of the emulsion polymers, dispersants are used which keep both the monomer droplets and the copolymer particles dispersed in the aqueous phase and thus ensure the stability of the aqueous copolymer dispersion produced. Suitable as such are both the protective colloids commonly used for carrying out free-radical aqueous emulsion polymerizations and emulsifiers.

Suitable protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or vinylpyrrolidone-containing copolymers. A detailed description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular substances, pages 41 1 to 420, Georg-Thieme-Verlag, Stuttgart, 1961. Of course, mixtures of emulsifiers and / or protective colloids can be used. Frequently used as dispersants only emulsifiers whose relative molecular weights, in contrast to the protective colloids are usually below 1000 g / mol. They may be anionic, cationic or nonionic in nature. Of course, in the case of the use of mixtures of surfactants, the individual components must be compatible with each other, which can be checked in case of doubt by hand on fewer preliminary tests. In general, anionic emulsifiers are compatible with one another and with nonionic emulsifiers. The same applies to cationic emulsifiers, while anionic and cationic emulsifiers are usually incompatible with each other.

Customary emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO degree: from 3 to 50, alkyl radical: C ₄ to C ₂₎ (, ethoxylated fatty alcohols, EO units: 3 to 50; alkyl radical: Cs to C36 ) as well as alkali metal and ammonium salts of alkyl sulfates (alkyl radical: Cs to C12), of sulfuric monoesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl radical: C12 to Cis) and ethoxylated alkylphenols (EO degree: 3 to 50, alkyl radical: C) ₄ to C12), of alkylsulfonic acids (alkyl radical: C12 to Cis) and of alkylarylsulfonic acids (alkyl radical: Cg to Cis). Further suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular substances, pages 192 to 208, Georg-Thieme-Verlag, Stuttgart, 1961.

As surface-active substances are also compounds of general formula I

wherein R ¹ and R ² is C ₄ - to C2 to ₄ alkyl and one of R ¹ or R ² can also be hydrogen, and A and B alkali metal ions and / or ammonium ions to be proven. In the general formula I, R ¹ and R ^{2 are} preferably linear or branched alkyl radicals having 6 to 18 C atoms, in particular having 6, 12 and 16 C atoms or H atoms, where R ¹ and R ^{2 are} not both simultaneously H and Atoms are. A and B are preferably sodium, potassium or ammonium ions, with sodium ions being particularly preferred. Particularly advantageous are compounds I in which A and B are sodium ions, R ^{1 is} a branched alkyl radical having 12 C atoms and R ^{2 is} an H atom or R ¹ . Industrial mixtures are used which have a share of 50 to 90 wt .-% of the monoalkylated product, for example Dowfax ^® 2A1 (Mar- ke of the Dow Chemical Company). The compounds I are generally known, for example from US-A 4,269,749, and commercially available.

Nonionic and / or anionic dispersing aids are preferably used. However, it is also possible to use cationic dispersing aids. In general, the amount of dispersant used is 0.1 to 5 wt .-%, preferably 0.5 to 3 wt .-%, each based on the total amount of monomer. The dispersing aid may for example be completely or partially charged in the polymerization vessel. The remaining dispersant can then be added at once or together with the monomers in portions or continuously.

The release of the free-radically initiated aqueous emulsion polymerization takes place by means of a free-radical polymerization initiator (free-radical initiator). In principle, these can be both peroxides and azo compounds. Of course, redox initiator systems are also suitable. As peroxides may in principle inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric, such as their mono- and di-sodium, potassium or ammonium salts or organic peroxides, such as alkyl hydroperoxides, for example tert-butyl, p-menthyl or cumyl hydroperoxide, and also dialkyl or diaryl peroxides, such as di-tert-butyl or di-cumyl peroxide. As an azo compound substantially 2,2 - azobis (isobutyronitrile), ^2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2 - azobis (amidinopropyl) dihydrochloride (AIBA, corresponding to V-50 from Wako Chemicals). Suitable oxidizing agents for redox initiator systems are essentially the abovementioned peroxides. Suitable reducing agents may be sulfur compounds having a low oxidation state, such as alkali metal sulphites, for example potassium and / or sodium sulphite, alkali hydrogen sulphites, for example potassium and / or sodium hydrogen sulphite, alkali metal bisulphites, for example potassium and / or sodium metabisulphite, formaldehyde sulphoxylates, for example potassium and / or sodium formate. aldehyde sulfoxylate, alkali metal salts, especially potassium and / or sodium salts, aliphatic sulfonic acids and alkali metal hydrogen sulfides, such as, for example, potassium and / or sodium hydro gen sulfide, salts of polyvalent metals, such as iron (II) sulfate, iron (II) ammonium sulfate , Iron (II) phosphate, endiols, such as dihydroxymaleic acid, benzoin and / or ascorbic acid, and reducing saccharides, such as sorbose, glucose, fructose and / or dihydroxyacetone. In general, the amount of the radical initiator used, based on the total amount of monomers, 0.01 to 5 wt .-%, preferably 0.1 to 3 wt .-% and particularly preferably 0.2 to 1, 5 wt .-%.

You can submit a subset or the total amount of free radical initiator in the polymerization vessel. However, it is also possible to meter the total amount or any residual amount of free radical initiator together with the monomers, but separately therefrom. In the emulsion polymerization, it is also possible to use further adjuvants familiar to the person skilled in the art, for example so-called thickeners, antifoams, neutralizing agents, preservatives, radical chain-transferring compounds and / or complexing agents.

In order to optimally adjust the rheology of the aqueous copolymer dispersions obtainable according to the invention during production, handling, storage and application, so-called thickeners or rheology additives are frequently used as the formulation constituent. The skilled worker is aware of a large number of different thickeners, for example organic thickeners, such as xanthan thickeners, guar thickeners (polysaccharides), carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, ethylhydroxyethylcellulose (cellulose derivatives), alkali-swellable dispersions (acrylate thickeners) or hydrophobically modified polyether-based polyurethanes (US Pat. Polyurethane thickener) or inorganic thickeners, such as bentonite, hectorite, smectite, attapulgite (Bentone) and titanates or zirconates (metal organyls).

In order to suppress or avoid foam formation in the preparation, handling, storage and application of the aqueous copolymer dispersions obtainable according to the invention, so-called antifoams are used. The defoamers are familiar to the person skilled in the art. These are essentially mineral oil and the silicone oil defoamers. Defoamers, especially the highly active silicone-containing, are generally very carefully selected and dosed, as they can lead to surface defects (craters, dents, etc.) of the coating. It is essential that the addition of finely divided, hydrophobic particles, such as hydrophobic silica or wax particles, in the defoamer, the defoaming effect can be increased.

If necessary, acids or bases known to those skilled in the art as neutralizing agents can be used to adjust the pH of the aqueous copolymer dispersions obtainable in accordance with the invention.

In order to prevent the infestation of the aqueous copolymer dispersions obtainable according to the invention during preparation, handling, storage and application by microorganisms, such as, for example, bacteria, (fungi) fungi or yeasts, preservatives or biocides familiar to the person skilled in the art are frequently used. In particular, combinations of active substances from methyl and chloroisothiazolinones, benzothiazolinones, formaldehyde or formaldehyde-releasing agents are used.

In addition to the abovementioned components, in the preparation of the aqueous copolymer dispersions it is optionally also possible to use free-radical chain-transferring compounds in order to increase the molecular weight of the polymers obtainable by the polymerization. to reduce copolymers or control. These are essentially aliphatic and / or araliphatic halogen compounds, such as, for example, n-butyl chloride, n-butyl bromide, n-butyl iodide, methylene chloride, ethylene dichloride, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tribromocarbon, benzyl chloride, benzyl bromide, organic thio compounds, such as primary, secondary or tertiary aliphatic thiols, such as ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3-pentanethiol, 2 Methyl 2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol, 4-methyl-2-pentanethiol , 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2-ethylbutanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and its isomeric compounds, n-octanethiol and its isomeric compounds, n-nonanethiol and its isomeric compounds, n-decanethiol and its isomeric V compounds, n-undecanethiol and its isomeric compounds, n-dodecanethiol and its isomeric compounds, n-tridecanethiol and its isomeric compounds, substituted thiols, such as, for example, 2-hydroxyethanethiol, aromatic thiols, such as benzenethiol, ortho, meta, or para methylbenzenethiol, and all other ^{approximately} in polymer Handbook 3 Edition, 1989, J. Brandrup and EH Immergut, John Weley & Sons, section II, pages 133 to 141, sulfur compounds described, as well as aliphatic and / or aromatic aldehydes such as acetaldehyde, propionaldehyde and / or benzaldehyde, unsaturated fatty acids such as oleic acid, dienes with non-conjugated double bonds, such as divinylmethane or vinylcyclohexane or hydrocarbons with readily abstractable hydrogen atoms, such as toluene, are used.

The total amount of the further optional auxiliaries, based on the total monomer amount, is generally <10% by weight, <5% by weight, often <3% by weight and frequently <1% by weight.

The total amounts or any remaining amounts of other optional auxiliaries may be added to the polymerization vessel batchwise in one or more portions or continuously or continuously with constant or varying flow rates. In particular, the dosage of other optional auxiliaries during the polymerization is carried out continuously with constant flow rates.

Optionally, the free-radically initiated aqueous emulsion polymerization in the presence of a polymer seed, for example in the presence of 0.01 to 10 wt .-%, often from 0.02 to 5 wt .-% and often from 0.04 to 1, 5 wt. -% of a polymer seed, in each case based on the total amount of monomers, carried out.

A polymer seed is used in particular when the particle size of the polymer particles to be produced by free-radical aqueous emulsion polymerization should be adjusted specifically (see, for example, US-A 2,520,959 and US-A 3,397,165).

In particular, polymer seed particles are used whose particle size distribution is narrow and whose weight-average diameter D _w <100 nm, frequently> 5 nm to <50 nm and often> 15 nm to <35 nm. The determination of the weight-average particle diameter is known to the person skilled in the art and is carried out, for example, by the method of the analytical ultracentrifuge. By weight-average particle diameter, this text is understood to mean the weight-average D _W 5o value determined by the method of the analytical ultracentrifuge (cf., for this purpose, SE Harding et al., Analytical Ultra-centrifugation in Biochemistry and Polymer Science, Royal Society of Chemistry, Cambridge , Great Britain 1992, Chapter 10, Analysis of Polymer Dispersions with an Eight Cell AUC Multiplexer: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pages 147 to 175).

A narrow particle size distribution should be understood within the scope of this document if the ratio of the weight-average particle diameter D _w determined by the method of the analytical ultracentrifuge and number-average particle diameter DN 50 [D _W 5O / DN 50] <2.0, preferably <1.5 preferably <1, 2 or <1, 1 is.

Usually, the polymer seed is used in the form of an aqueous polymer dispersion. The aforementioned amounts are based on the polymer solids content of the aqueous Polymersaatdispersion; they are therefore given as parts by weight of polymer seed solids, based on the total amount of monomer.

If a polymer seed is used, it is advantageous to use a foreign polymer seed. In contrast to a so-called in situ polymer seed which is prepared before the actual emulsion polymerization in the reaction vessel and which has the same monomer composition as the polymer prepared by the subsequent free-radically initiated aqueous emulsion polymerization, a foreign polymer seed is understood to mean a polymer seed which is in a separate state Reaction step is prepared and their monomer composition is different from the polymer prepared by the free-radically initiated aqueous emulsion polymerization, which means nothing else than that different monomers or monomer mixtures are used with different composition for the preparation of Fremdpolymersaat and for the preparation of the aqueous Polymerisatdispersion. The preparation of a foreign polymer seed is familiar to the person skilled in the art and is usually carried out by initially charging a relatively small amount of monomers and a relatively large amount of emulsifiers in a reaction vessel and adding a sufficient amount of polymerization initiator at reaction temperature. Preference is given to using a foreign metal seed having a glass transition temperature> 50 ^° C., frequently> 60 ^° C. or> 70 ^° C. and often> 80 ^° C. or> 90 ^° C. Particularly preferred is a polystyrene or a polymethyl methacrylate polymer seed. It is possible to optionally introduce a partial amount or the total amount of foreign polymer seed as a further optional adjuvant in the polymerization vessel and then to start the polymerization. However, it is also possible to meter in the total amount or any remaining amounts of foreign polymer seed during the polymerization.

The total amounts or any residual amounts of Fremdpolymersaat may be added to the polymerization vessel discontinuously in one or more portions or continuously with a constant or changing flow rate metered. Preferably, the total amount of foreign polymer seed is placed in the polymerization vessel.

By polymerization conditions are meant those temperatures and pressures below which the free-radically initiated aqueous emulsion polymerization proceeds at a sufficient rate of polymerization. The rate of polymerization depends in particular on the particular radical initiator used. Advantageously, the nature and amount of the free-radical initiator, the polymerization temperature and the polymerization pressure are selected such that the free-radical initiator has a half-life <3 hours, more preferably <1 hour and most preferably <30 minutes.

Depending on the radical initiator chosen, the reaction temperature for the free-radical aqueous emulsion polymerization according to the invention is the entire range from 0 to 120 ^° C. In this case, temperatures of 50 to 100 ⁰ C, in particular 60 to 95 ⁰ C and advantageously used 70 to 90 ⁰ C in the rule. The radical aqueous emulsion polymerization can be carried out at a pressure of less than or equal to 1 atm (absolute), such that the polymerization temperature can exceed 100 ^° C. and can be up to 120 ^° C. When the emulsion polymerization is carried out under reduced pressure, pressures of 950 mbar, often 900 mbar and often 850 mbar (absolute) are set. The free-radical aqueous emulsion polymerization is advantageously carried out under atmospheric pressure (1 atm or 1.01 bar absolute) under an inert gas atmosphere, for example under nitrogen or argon.

In principle, the aqueous reaction medium may also comprise small amounts of water-soluble organic solvents, such as, for example, methanol, ethanol, isopropanol, butanols, pentanols, but also acetone, etc. However, the polymerization is preferably carried out in the absence of organic solvents. The resulting aqueous polymer dispersion usually has a polymer solids content of> 10 and <70 wt .-%, often> 20 and <65 wt .-% and often> 40 and <60 wt .-%, each based on the aqueous copolymer dispersion on. The number-average particle diameter (cumulant z-average) determined by quasi-elastic light scattering (ISO Standard 13 321) is generally between 10 and at most 1000 nm, frequently between 20 and less than 500 nm and often between 30 and 400 nm.

In order to reduce the residual monomer content of the aqueous dispersions, they can optionally be subjected to postpolymerization, for example, after completion of the main polymerization, an initiator or at least two initiators having a different half-life, added to the dispersion and the mixture is then heated to a temperature at the main polymerization has been carried out or is below or above the temperature maintained in the main polymerization.

The residual monomer content of the aqueous dispersion and the content of other low-boiling compounds can also be known by the skilled person chemical and / or physical methods [see, for example, EP-A 771 328, DE-A 196 24 029, DE-A 196 21 027, DE-A 197 41 184, DE-A 197 41 187, DE-A 198 05 122, DE-A 198 28 183, DE-A 198 39 199, DE-A 198 40 586 and DE-A 198 47 115] be lowered.

The invention also provides water-absorbing materials comprising a carrier material and a water-absorbing compound, which are obtainable by applying an aqueous dispersion of a crosslinked emulsion polymer which

(a) at least 50% by weight of an ester derived from a tertiary alcohol and an ethylenically unsaturated C3 to C5 carboxylic acid,

(B) 0.001 to 5.0 wt .-% of at least one compound having at least two ethylenically unsaturated double bonds, and

contains polymerized and has an average particle size of at most 1000 nm, on a support material, drying and heating the thus treated support material to a temperature of at least 130 ⁰ C to form carboxyl groups from the tertiary ester groups of the emulsion polymer and at least partially neutralization of the carboxyl groups. To prepare the water-absorbent materials, it is preferable to use a crosslinked emulsion polymer which

(B) 0.01 to 2.0 wt .-% of at least one compound having at least two ethylenically unsaturated double bonds, and

(c) 0 to 49.99% by weight of at least one other monoethylenically unsaturated compound

contains polymerized and has an average particle size of at most 500 nm, on a support material.

Preferred water-absorbing materials are obtainable by first coating a support material with a crosslinked emulsion polymer which

(A) 98.0 to 99.99 wt .-% of at least one tert-butyl ester of an ethylenically unsaturated C3 to Cδ carboxylic acid and

(b) 0.01 to 2.0% by weight of at least one compound which has at least two ethylenically unsaturated double bonds,

contains polymerized and has an average particle size of 30 to 400 nm, the coated support material then dried, by heating to a temperature of at least 130 ⁰ C from the crosslinked emulsion polymer olefins cleaves to form carboxyl groups and the carboxyl groups at least partially neutralized. The substrate coated with the crosslinked emulsion polymer carrier material is heated, for example to a temperature in the range 130-250 ⁰ C, preferably 140 to 200 ° C, usually 160 to 190 ° C. The residence time of the coated support material under the given temperature conditions depends on the level of the particular temperature selected and on the degree of hydrolysis of the units contained in the crosslinked emulsion polymer to tertiary ester groups from which carboxyl groups are formed during the hydrolysis. It is for example 2 minutes to 5 hours, usually 10 minutes to 2 hours. For example, 10 to 100%, preferably 80 to 95%, of the tertiary ester groups of the crosslinked emulsion polymer are converted into carboxyl groups.

In order to achieve the highest possible water absorption, it is necessary that the carboxyl groups formed from the tertiary ester groups are at least partially neutralized. The degree of neutralization of the carboxyl groups is for example 50 to 100%, preferably 70 to 100% and is usually in the range of 80 to 95%. The neutralizing agent used is, for example, an alkali metal and / or ammonium base and / or an alkaline earth metal base. examples for this are Sodium hydroxide solution, potassium hydroxide solution, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonia and amines, preferably ethanolamine, diethanolamine, triethanolamine and morpholine, calcium hydroxide and magnesium oxide. Aqueous sodium hydroxide solution, ethanolamine, diethanolamine and triethanolamine are preferably used as the neutralizing agent.

After the neutralization step, the water-absorbing material is dried, e.g. contains after drying virtually no more water or at most 10 wt .-% water. The water content of the dried material is usually below 5% by weight.

The water-absorbing materials are preferably prepared from a crosslinked emulsion polymer which comprises tert-butyl acrylate and / or tert-butyl methacrylate as the monomer of group (a) and as the monomer of group (b) allyl methacrylate, butanediol diacrylate, divinylbenzene or mixtures thereof contains polymerized.

The concentration of crosslinked emulsion polymer in the aqueous dispersions, with which carrier materials for the preparation of the water-absorbing materials are treated, for example, 5 to 30 wt .-%, preferably 10 to 25 wt .-%. However, it is also possible to use preparation solutions which have a lower or a higher content of emulsion polymer. The amount of crosslinked emulsion polymer which is applied to the carrier material is, for example, 5 to 500% by weight, preferably 30 to 300% by weight, based on the carrier material.

As carrier material are preferably paper, paperboard, cardboard, nonwovens, woven fabrics, knitted fabrics, silica gel, silicates, mineral building materials, foams of melamine-formaldehyde resins and foams of polyurethanes into consideration.

The treatment of a carrier material with an at least partially neutralized polymer described above gives water-absorbing materials. They are used as absorbents for water and aqueous liquids either alone or in absorbent compositions. In the absorbent composition, the water-absorbing materials according to the invention are present in or are fixed to an absorption medium.

A carrier material for receiving the water-absorbing, at least partially neutralized polymers may, for. Example, be a fiber matrix, which consists of a cellulose fiber mixture (airlaid web, wet laid web) or of synthetic polymer fibers

(meltblown web, spunbonded web), or from a mixed fiber plant of CeIIU loose fibers and synthetic fibers. Furthermore, open-cell foams or the like can serve to incorporate the water-absorbing materials.

Alternatively, such an absorbent composition may be formed by fusing two monolayers to form one or more of a plurality of chambers containing the water-absorbing polymers. In this case, at least one of the two layers should be water permeable. The second layer can either be water-permeable or impermeable to water. Tissues or fabrics, closed or open-cell foams, perforated films, elastomers or fabrics of fibrous material can be used as the layer material. When the absorbent composition is a series of layers, the layer material should have a pore structure whose pore dimensions are small enough to retain the water-absorbing polymers. The above examples of the construction of the absorbent composition also include laminates of at least two layers between which the water-absorbing polymers are incorporated and fixed.

Furthermore, the absorption medium of a carrier material, such as. Example, consist of a polymer film on which the water-absorbing polymers are fixed. The fixation can be made both on one side and on both sides. The carrier material may be water-permeable or impermeable to water.

The structure of the present absorbent materials according to the invention comprising at least one carrier material and water-absorbing polymers is based on a variety of fiber materials which are used as a fiber network or matrices. Included in the present invention are both fibers of natural origin (modified or unmodified) and synthetic fibers.

Examples of cellulosic fibers include those commonly used in absorbent products, such as fluff pulp and cotton type pulp. Furthermore, fibers from conifers or hardwoods, as well as chemical pulp, semi-chemical pulp, chemothermic mechanical pulp (CTMP), pressure groundwood (PGW), wood pulp, sulphate and sulphite pulp and fibers from recovered paper are suitable as carrier material. Both bleached and unbleached fibers can be used. For example, natural cellulose fibers such as cotton, flax and jute, as well as ethyl cellulose and cellulose acetate are used. In addition, one can use fibers of silk or wool or flat structures produced therefrom as a carrier material.

Suitable synthetic fibers are prepared, for example, from polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylic compounds such as ORLON®, polyvinyl acetate, polyethyl vinyl acetate, soluble or insoluble polyvinyl alcohol. Examples of synthetic fibers include thermoplastic polyolefin fibers, such as polyethylene fibers (PULPEX ^®), polypropylene fibers and polyethylene-polypropylene bicomponent fibers, polyester fibers, such as polyethylene terephthalate (DA CRON ^® or KODEL ^®), copolyesters, polyvinyl acetate, polyethylvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylics, polyamides, copolyamides, polystyrene and copolymers of the above- Polyethylene terephthalate-polyethylene-isophthalate copolymer, polyethylvinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, copolyester / polyester, polyamide fibers (nylon), polyurethane fibers, polystyrene fibers and polyacrylonitrile fibers. Preference is given to polyolefin fibers, polyester fibers and their bicomponent fibers. Further preferred are thermoset two-component fibers of sheath-core type and side-by-side type polyolefin because of their excellent dimensional stability after liquid absorption.

The said natural fibers are preferably used in combination with thermoplastic fibers. During the heat treatment, the latter partly migrate into the matrix of the existing fiber material and thus form connecting points and renewed stiffening elements on cooling. In addition, the addition of thermoplastic fibers means an extension of the pore dimensions present after heat treatment. In this way it is possible, by continuously adding thermoplastic fibers during the formation of the absorption layer, to continuously increase the proportion of thermoplastic fibers to the cover sheet, which results in a likewise continuous increase in the pore sizes. Thermoplastic fibers can be formed from a variety of thermoplastic polymers that aufwei- a melting point of less than 190 ⁰ C, preferably between 75 ⁰ C and 175 ⁰ C sen. At these temperatures, no damage to the cellulose fibers is to be expected.

Lengths and diameters of the above-described synthetic fibers are not limited. In general, any fiber with a length of e.g. 1 to 200 mm and a diameter of 0.1 to 100 denier (grams per 9,000 meters) are preferably used. Preferred thermoplastic fibers have a length of 3 to 50 mm, more preferably a length of 6 to 12 mm. The preferred diameter of the thermoplastic fiber is between 1, 4 and 10 decitex, more preferably between 1, 7 and 3.3 decitex (grams per 10 000 meters). The shape may be arbitrary, examples include tissue-like, narrow cylinder-like, cut / split yarn-like, staple fiber-like, and endless fiber-like ones.

The fibers in the water-absorbent composition of the invention may be hydrophilic, hydrophobic or a combination of both. As defined by Robert F. Gould in the publication "Contact Angles, Wettability and Adhesion", American Chemical Society (1964), a fiber is said to be hydrophilic when the contact angle between the liquid and the fiber (or its surface) is is smaller than 90 °, or if the liquid tends to spontaneously spread on the same surface. Both processes are usually coexistent. Conversely, a fiber is said to be hydrophobic if a contact angle of greater than 90 ° is formed and no spreading is observed.

Preference is given to using hydrophilic fiber material. Fiber material is particularly preferably used which is weakly hydrophilic towards the body side and most hydrophilic in the region around the water-absorbing polymers. In the manufacturing process, by using layers of differing hydrophilicity, a grave is created which channels the impinging liquid to the water-absorbing polymeric material where ultimately absorption takes place.

Suitable hydrophilic fibers for use in the absorbent composition according to the invention are, for example, cellulose fibers, modified cellulose fibers, rayon, polyester fibers, such as e.g. As polyethylene terephthalate (DACRON®), and hydrophilic nylon (HYDROFI L ^®). Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as the treatment of thermoplastic fibers obtained from polyolefins (such as polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.) with surfactants or silica. However, for reasons of cost and availability, cellulose fibers are preferred.

The liquid-receiving and -istrating fiber matrix may consist of synthetic fiber or cellulose fiber or a mixture of synthetic fiber and cellulose fiber, wherein the mixing ratio of (100 to 0) synthetic fiber: (0 to 100) cellulose fiber may vary. The cellulose fibers used may additionally be chemically stiffened to increase the dimensional stability of the absorbent composition.

The chemical stiffening of cellulose fibers can be achieved in different ways. On the one hand, a fiber stiffening can be achieved by adding suitable coatings to the fiber material. Such additives include for example polyamide-epichlorohydrin coatings (Kymene ^® 557H, Hercoles, Inc. Wii Remington Delaware, USA), polyacrylamide coatings (described in US Patent No. 3,556,932 or as a product of Parez ^® 631 NC trademark, American Cyanamid Co. , Stamford, CT, USA), melamine-formaldehyde coatings, and polyethylenimine coatings.

The chemical stiffening of cellulose fibers can also be done by chemical reaction. So z. For example, the addition of suitable crosslinker substances can cause crosslinking that occurs within the fiber. Suitable crosslinker substances are typical substances which are used for crosslinking monomers. With including but not limited to C2-C8 dialdehydes, C2-C8 monoaldehydes with acidic functionality, and especially C2-C9 polycarboxylic acids. Specific substances from this series are, for example, glutaraldehyde, glyoxal, glyoxylic acid, formaldehyde and citric acid. These substances react with at least 2 hydroxyl groups within a single cellulose chain or between two adjacent cellulose chains within a single cellulosic fiber. The crosslinking results in a distribution of the fibers, which gives this treatment a greater dimensional stability. In addition to their hydrophilic character, these fibers have uniform combinations of stiffening and elasticity. This physical property makes it possible to maintain the capillary structure even with simultaneous contact with liquid and compressive forces and to prevent premature collapse.

Chemically crosslinked cellulosic fibers are known and described in WO 91/11162, U.S. Pat. U.S. Patent 3,224,926, U.S. Pat. U.S. 3,440,135, U.S. U.S. Patent 3,932,209 U.S. Patent 4,035,147, U.S. U.S. Patent 4,822,453, U.S. Pat. U.S. Patent 4,888,093, U.S. Pat. U.S. Patent 4,898,642 and U.S. Pat. Patent 5,137,537. The chemical crosslinking causes a stiffening of the fiber material, which is ultimately reflected in an improved dimensional stability of the absorbent composition. Although chemically crosslinked cellulose fibers are somewhat more hydrophobic than untreated cellulose fibers; However, since the use of crosslinked cellulose fibers in the absorbent composition according to the invention is not intended for liquid storage or buffering due to the high proportion of absorbent composition, but solely for liquid transport, the hydrophobing has no negative effect on the absorption profile. The individual layers are known by those skilled methods, such. B. Fusion by heat treatment, addition of hot melt adhesives, latex binders, etc. interconnected.

In addition, all paper grades, e.g. Papers for newspaper printing, so-called medium-fine writing and printing papers,

Natural gravure papers and lightweight base papers as well as cardboard and cardboard, single / multi-layer carton, single / multi-layer liner, corrugating medium. For example, wood pulp, thermomechanical pulp (TMP), chemo-thermo-mechanical pulp (CTMP), pressure pulp (PGW), hollow pulp, sulphite pulp and sulphate pulp, as well as fibers from recovered paper, can be used to make such papers. It is possible to use both the pure paper materials and mixtures of two or more paper materials, in particular fibers from waste paper-containing fiber mixtures, for the production of suitable carrier materials. The pulps can be short fiber as well as long fiber. The dispersions of crosslinked emulsion polymers are preferably applied to paper and paper products on one or both sides. However, they can also be added to the pulp prior to sheet formation in papermaking. The water-absorbing materials according to the invention can be used in all areas in which it comes to bind aqueous liquids quickly and permanently. Examples of such applications include industrial applications as well as hygiene applications.

As exemplary applications may be mentioned, without being limited to:

horticulture

Medicine (wound plaster, water absorbing material for burn dressings or for other weeping wounds, quick bandages for injuries, rapid absorption of exuding body fluids for subsequent analysis and diagnosis), carrier material for pharmaceuticals and drugs, rheumatism, ultrasound gel, cooling gel cosmetics, cosmetic thickener, sunscreen thickener for oil / Water or water / oil emulsions

Textile (gloves, sportswear, moisture regulation in textiles,

Shoe inserts, synthetic fabrics)

Hydrophilization of hydrophobic surfaces; poration

Chemical process industry. Applications (catalyst for organic reactions, immobilization of large functional molecules (enzymes), heat storage, filtration aids, hydrophilic component in polymer laminates, dispersants, condenser) Construction and construction, (sealants, in the presence of moisture self-sealing systems or self-sealing films; Sintered building materials or ceramics; Self-sealing insulation for water pipes or for pipes and pipes buried in the ground; Waterproofing of building materials in the soil, which is achieved by the water-absorbing material swelling in the moist soil with a time delay, and thus a closure or waterproofing, carpet and carpet finishing equipment), installation, anti-vibration medium, aids in tunnel excavation in water-rich subsoil, auxiliary equipment

Excavation and drilling in water-rich underground, cable coating fire protection

Coextrusion agents in thermoplastic polymers; Production of films and thermoplastic moldings capable of absorbing water (eg rainwater and condensation water-retaining films for agriculture; films containing water-absorbent materials for keeping fruit and vegetables fresh, which can be packed in damp films to prevent rottenness and wilting); Coextrudates of water-absorbing materials, eg with polystyrene carrier in active ingredient formulations (pharmaceuticals, plant protection) - agribusiness: protection of forests from fungal / insect attack, delayed release of active substances to plants) Preferably, the water-absorbing materials are used in the form of an absorbent composition. The preferred fields of application of the water-absorbing materials according to the invention in the industrial sector and in the use of hygiene are, for example, the use as wipes, paper towels, upholstery, pillows, in absorbent products in the medical sector and in household and industrial absorbent products.

One aspect of the use of the water-absorbent materials according to the present invention relates to the use in wipes. The field of use of water-absorbent materials in wipes includes wipes for cleaning purposes, such as in moistened cleaning sponges for cleaning floor surfaces, or generally for removing dirt from surfaces. The main application of wipes includes industry, household and hygiene, especially baby care. Examples include industrial wipes, floorcloths and laps, wet wipes, household wipes (to remove oil, water, biological fluids), food grade wipers (food service), dishtowels, car wipes, and moreover, wipes for cleaning solid surfaces such as Glass surfaces, kitchen, furniture, bathroom; Wipes for industrial cleaning of solid surfaces of all kinds, wipes for removing chemical contaminants; further, wipes in personal care applications, such as skin and facial cleansing, application and removal of cosmetics, hair conditioners, restoratives, and / or health care skin care products; Wipes for cleaning and / or treating clothing and textiles; Wipes for infant care, such as bibs, diapers, and for use in health care, such as bandages, antimicrobial sanitary towels listed.

A second aspect of the use of the water-absorbing materials according to the present invention relates to use in paper towels. Examples of these include facial tissues, cleaning wipes, bath towels, paper towels, traveling wipes (travel towels), and absorbent paper products. The paper towels are used to improve skin care, as well as to remove dirt, microbes, bacteria of all kinds, fungi (yeast and mold), protozoa, viruses, and other substances from the skin surface. Paper towels are also used in fresh meat / fresh fish bowls to absorb the meat juice used.

A third aspect of the use of the water-absorbing materials according to the present invention relates to the use in upholstery / cushions. Examples include scouring pads, polishing pads, emery pads, generally cleaning pads (- cotton wool) for body and wound care, such as for the absorption of sweat, menstrual fluids, as a base when changing the hygienic product, use in bed pads, shoe inserts, in upholstery, as well as in textiles, such as forearm pads for sweat absorption, panties for the absorption of menstrual fluids

A fourth aspect of the use of the water-absorbing materials according to the present invention relates to the use in medical-sector absorbent products. Examples include medical apparel (utility, surgery), such as surgical gowns / coats, disposable garments, headgear, gloves, face masks; Wound care and care articles, such as wound wraps, wound dressings, bandages, (waste) containers, filters, rolled nonwoven articles (in medicine / dentistry); and absorbent bedding, medical wipes / tissues, medical underpads, and as an absorbent product for medical or dental treatments.

A fifth aspect of the use of the water-absorbent materials according to the present invention relates to the use in household and industrial absorbent products. Examples include construction and packaging accessories, products for cleaning and disinfecting, cloths, covers, filters, towels, disposable cutting pads, bath towels, facial tissues; Household goods such as pillows, upholstery, and skin care products such as masks, skin and facial care products, textiles such as lab coats, covers; the further use in the garbage bag, as stain remover, topical compositions, dirt / ink remover of contaminated laundry; for the agglomeration of surfactants; as well as separators of lipophilic liquids.

Other optional uses of the water-absorbent materials according to the present invention include: use in tablecloths, surgical drapes, bandages, in absorbent compositions for incorporation into sanitary articles such as diapers, feminine hygiene and adult incontinence. Furthermore, the water-absorbing materials are used in floor mats, such as in the kitchen for the absorption of aqueous liquids, in garages for the absorption of hydrophobic liquids, as shoe inserts, boat inserts used. It can also be used in indoor and outdoor (outdoor) applications, in garages, vehicles, offices, vending machines (vending machines), refrigerators, as a defrosting aid for defrosting food, in restaurants, schools, utilities, emergency rooms, sports and gyms, showers, hospitals. They are also suitable for receiving spilled or spilled liquids, such as in the industry, as a use of floor mats or door mats for wet / damp / dirty shoes, pets, umbrellas, snow, etc .; as protective coverings on car seats, carpet protectors, trunk decking; under high chairs, under chairs / tables tinkered or played as a nappy-changing pad, in front of or under sinks, in front of or below devices which may be leaking or overflowing, in the refrigerator as shelf support or under thawing products (meat, fish, vegetables); under the sideboard; in the storage room under oil-containing products; in the garage for the absorption of oil, gasoline, and spilled or spilled liquids; under green plants in the house, under feeding bowls and water tanks of domestic animals, under waste containers, as floor mats in pet cages, as a cover or covering of duvet covers or as a base for incontinence; for receiving spilled liquids and cleaning soiled surfaces; as bath mats; as mats around the toilet area; in the stadium (cover, seat protection) for protection against dampness and for insulation, disposable coasters or blankets; in food / beverage facilities; as a tripod. Further possible uses are bed mats, filter pads (air filter bag, antibacterial protective filter), filter materials for removing moisture from non-aqueous filtrates. In the hygiene application, the absorbent compositions of the invention also find use in sanitary articles, such as diapers or diapers, or for the detection of moisture, moisture and / or biological fluids and / or chemical liquids in the absorbent structure; as packaging materials; as a water-retaining or water-sealing agent.

The water-absorbing materials according to the invention are further used together with fabric-like nonwoven materials, with agricultural substrates, in covers and food packaging

Examples

The average particle diameter of the polymer particles was generally determined by dynamic light scattering on a 0.01 weight percent aqueous dispersion at 23 ° C. by means of Autosizer NC from Malvern Instruments, England. The mean diameter of the cumulant evaluation (cumulant z-average) of the measured autocorrelation function (ISO standard 13321) is given.

Preparation of the dispersions

example 1

A mixture of 313.1 g of deionized water and 9.1 g of a 33% strength by weight aqueous polymer latex (prepared by free-radically initiated emulsion polymerization of styrene) was carried in a 2 l stirred-flow reactor with heating / cooling a weight average particle diameter Dwso of 30 nm under nitrogen atmosphere at 80 ⁰ C heated. 8.0 g of a 7% by weight aqueous solution of sodium peroxodisulfate were added thereto at the above-mentioned temperature. After 5 minutes, the inlet 1 and inlet 2 started. Feed 1 and feed 2 were metered in uniformly over 3 h.

Feed 1 was an aqueous emulsion prepared from

394.4 g of deionized water

26.8 g of a 28% strength by weight aqueous solution of the sodium salt of a fatty alcohol ether sulfate having C 12 -C 14 -alkyl radical and a degree of ethoxylation of 3 to 5 (Texapon® NSO from Cognis) 748.1 g of tert-butyl acrylate 1, 9 g of allyl methacrylate

Feed 2 consisted of 24.1 g of a 7% strength by weight aqueous solution of sodium peroxodisulfate.

After the end of feeds 2 and 3, the reaction mixture was stirred for one hour at 80 ⁰ C and then cooled to room temperature. The aqueous polymer dispersion obtained had an average particle size of 208 nm.

Example 2

A dispersion was prepared according to the procedure of Example 1 with the following difference:

Feed 1 contained 746.3 g of tert-butyl acrylate and 3.8 g of allyl methacrylate.

The aqueous polymer dispersion obtained had an average particle size of

206 nm.

Example 3

Feed 1 contained 742.5 g of tert-butyl acrylate and 7.5 g of allyl methacrylate.

The aqueous polymer dispersion obtained had an average particle size of

207 nm. Example 4

Feed 1 contained 749.3 g of tert-butyl acrylate and 0.8 g of allyl methacrylate.

The aqueous polymer dispersion obtained had an average particle size of 209 nm.

Example 5

The receiver in the reactor contained 2.3 g of a 33 wt .-% aqueous polymer latex (prepared by free-radically initiated emulsion polymerization of styrene) having a weight-average particle diameter DW50 of 30 nm.

The aqueous polymer dispersion obtained had an average particle size of 277 nm.

Production and swelling of water-absorbing materials

Comparative Example 1

In order to be able to associate the weight increase of the water-absorbing materials produced according to the invention with the absorption of water in the crosslinked polymer applied to the substrate, a strip of filter paper of size 8 × 3 cm (weight 0.24 g) was annealed at 140 ^° C. under air for 5 hours , Then immersed for 10 seconds in a 5% strength by weight aqueous sodium hydroxide solution and then dried in air. The weight was still 0.24 g. After immersion in demineralized water, a drained weight of 0.54 g was obtained after 10 seconds or more.

Example 6

A strip of filter paper of size 8 × 3 cm (weight 0.23 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 1 and then dried in air. The dried sample had a weight of 0.35 g. It was annealed for 5 h at 140 ^° C. under air, whereby the weight decreased to 0.30 g. The sample material was then immersed for 10 seconds in a 5 wt .-% aqueous sodium hydroxide solution and then dried in air. The air-dry water- Serabsorbierende material had a weight of 0.35 g. The swelling by immersion in demineralized water gave after 5 sec, an increase in weight to 0.88 g and after 120 sec, an increase in weight to 1, 76 g.

Example 7

A strip of filter paper of size 8 × 3 cm (weight 0.24 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 2 and then dried in air. The dried sample had a weight of 0.38 g. It was annealed at 140 ^° C. under air for 5 h, reducing the weight to 0.34 g. The sample material was then immersed for 20 seconds in a 5 wt .-% aqueous ammonia solution and then dried in air. The air-dry water-absorbent material weighed 0.35 g. The swelling by immersion in demineralized water after 60 sec increased weight to 1.88 g.

Example 8

A strip of filter paper of size 8 × 3 cm (weight 0.24 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 3 and then dried in air. The dried sample weighed 0.38 g. It was annealed at 140 ^° C. under air for 5 h, reducing the weight to 0.34 g. The sample material was then immersed for 10 seconds in a 5 wt .-% aqueous sodium hydroxide solution and then dried in air. The air-dry water-absorbent material had a weight of 0.4 g. The swelling by immersion in deionized water after 120 sec showed a weight gain to 1, 45 g.

Example 9

A strip of filter paper of size 8 × 3 cm (weight 0.23 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 1 and then dried in air. The dried sample weighed 0.37 g. It was annealed for 17 min at 160 ^° C. under air, reducing the weight to 0.32 g. The sample material was then immersed for 10 seconds in a 5 wt .-% aqueous sodium hydroxide solution and then dried in air. The air-dry water-absorbent material had a weight of 0.38 g. The swelling by immersion in demineralized water gave after 10 sec, a weight gain to 1, 05 g. Example 10

A strip of filter paper of size 8 × 3 cm (weight 0.23 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 1 and then dried in air. The dried sample weighed 0.37 g. It was annealed for 16 min at 180 ⁰ C under air, whereby the weight decreased to 0.31 g. The sample material was then immersed for 10 seconds in a 5 wt .-% aqueous sodium hydroxide solution and then dried in air. The air-dry water-absorbent material had a weight of 0.38 g. The swelling by immersion in demineralized water gave rise to a weight gain of 1.14 g after 10 sec.

Example 1 1

A strip of filter paper of size 8 × 3 cm (weight 0.24 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 4 and then dried in air. The dried sample weighed 0.38 g. It was annealed at 140 ^° C. under air for 5 h, whereby the weight decreased to 0.33 g. The sample material was then immersed in a 5% strength by weight aqueous sodium hydroxide solution for 10 seconds and then dried in air. The air-dry water-absorbent material had a weight of 0.36 g. The swelling by immersion in demineralized water gave after 10 sec, an increase in weight to 1, 13 g and after 60 sec, an increase in weight to 1, 73 g.

Example 12

A strip of filter paper of size 8 × 3 cm (weight 0.24 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 5 and then dried in air. The dried sample had a weight of 0.39 g. It was annealed for 5 h at 140 ^° C. under air, whereby the weight decreased to 0.36 g. The sample material was then immersed for 10 seconds in a 5 wt .-% aqueous sodium hydroxide solution and then dried in air. The air-dry water-absorbent material had a weight of 0.38 g. The swelling by immersion in demineralized water gave after 10 sec, a weight gain to 0.86 g and after 60 sec, an increase in weight to 1, 11 g.

Example 13

A cellulosic nonwoven (size: 1 × 8.5 cm (weight: 0.45 g), freed of bebe-young-care facial cleansing cloth from the Johnson & Johnson Company by washing with water several times, was placed in a volume ratio of 1 for 10 sec 1 immersed with water dispersion according to Example 1 dipped and then in air dried. The dried sample weighed 1.39 g. It was annealed for 5 h at 140 ^° C. under air, whereby the weight decreased to 1.00 g. The sample material was then immersed for 30 seconds in a 5 wt .-% aqueous solution of triethanolamine and then dried in air. The air-dry water-absorbent material weighed 2.10 g. The swelling by immersion in demineralized water gave after 60 sec, an increase in weight to 19.43 g.

Example 14

A strip of filter paper of size 8 × 3 cm (weight 0.23 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 1 and then dried in air. The dried sample weighed 0.36 g. It was annealed at 140 ^° C. under air for 5 h, reducing the weight to 0.31 g. The sample material was then immersed for 10 seconds in a 5% strength by weight aqueous solution of triethanolamine and then dried in air. The air-dry water-absorbent material had a weight of 0.34 g. The swelling by immersion in demineralized water gave after 5 sec, an increase in weight to 1, 02 g.

Example 15

A strip of filter paper of size 8 × 3 cm (weight 0.23 g) was immersed for 10 sec in a volume ratio of 1: 1 diluted with water dispersion according to Example 1 and then dried in air. The dried sample had a weight of 0.35 g. It was annealed at 140 ^° C. under air for 5 h, whereby the weight decreased to 0.29 g. The sample material was then immersed for 10 seconds in a 10 wt .-% aqueous solution of triethanolamine and then dried in air. The air-dry water-absorbent material weighed 0.57 g. The swelling by immersion in demineralized water gave after 20 sec, an increase in weight to 2.76 g.

Claims

claims

1. Aqueous dispersions of crosslinked, tertiary ester group-containing E matrialspolymerisaten, characterized in that the Emulsionspolymeri- sowing

2. Aqueous dispersions according to claim 1, characterized in that the emulsion polymers

(a) at least 90% by weight of a tert-butyl ester of an ethylenically unsaturated C3 to C5 carboxylic acid,

3. Aqueous dispersions according to claim 1 or 2, characterized in that the emulsion polymers

(A) 98.0 to 99.99 wt .-% of at least one tert-butyl ester of an ethylenically unsaturated C3 to Cs carboxylic acid and (b) 0.01 to 2.0 wt .-% of at least one compound which at least has two ethylenically unsaturated double bonds,

4. Aqueous dispersions according to any one of claims 1 to 3, characterized in that the emulsion polymers as the monomer of group (a) tert-butyl acrylate and / or tert-butyl methacrylate and as a monomer of group (b) AI- lylmethacrylat, Butandioldiacrylat, divinylbenzene or mixtures thereof einpoly- merisiert.

5. Water-absorbing materials comprising a support material and a water-absorbing compound, characterized in that they are obtainable by applying an aqueous dispersions of a crosslinked emulsion polymer, the

contains polymerized and has an average particle size of at most 1000 nm, on a support material, drying and heating the thus treated support material to a temperature of at least 140 ⁰ C to form carbo xylgruppen from the tertiary ester groups of the emulsion polymer and at least partially neutralization of carboxyl groups.

6. Water-absorbing materials according to claim 5, characterized in that the crosslinked emulsion polymer

contains polymerized and has a mean particle size of at most 500 nm.

7. Water-absorbing materials according to claim 5, characterized in that the crosslinked emulsion polymer

(A) 98.0 to 99.99 wt .-% of at least one tert-butyl ester of an ethylenically unsaturated C3 to Cs carboxylic acid and (b) 0.01 to 2.0 wt .-% of at least one compound which at least has two ethylenically unsaturated double bonds, contains polymerized and has an average particle size of 30 to 400 nm.

8. Water-absorbing materials according to claim 5, characterized in that the crosslinked emulsion polymer as monomer of group (a) tert-butyl acrylate and / or tert-butyl methacrylate and as monomer of the group (b) allyl methacrylate, butanediol diacrylate, divinylbenzene or mixtures thereof contains polymerized.

9. Water-absorbing materials according to any one of claims 5 to 8, characterized in that the substrate treated with a crosslinked emulsion polymer is heated to a temperature in the range of 140 to 220 ⁰ C.

10. Water-absorbing materials according to one of claims 5 to 9, characterized in that 10 to 100% of the tertiary ester groups of the crosslinked

Emulsionspoylmerisats are converted into carboxyl groups.

1 1. Water-absorbing materials according to any one of claims 5 to 10, characterized in that the applied to the carrier material amount of crosslinked emulsion polymer 5 to 500 wt .-%, based on the carrier material is.

12. Water-absorbing materials according to any one of claims 5 to 10, characterized in that the applied to the carrier material amount of crosslinked emulsion polymer 30 to 300 wt .-%, based on the carrier material.

13. Water-absorbing materials according to any one of claims 5 to 12, characterized in that the carrier material is selected from the group consisting of paper, cardboard, non-woven, woven, knitted, silica, silicates, mineral building materials, foams of melamine-formaldehyde resins and Polyurethane foams.

14. Use of water-absorbing materials according to one or more of claims 5 to 13 as an absorbent for water and aqueous liquids.

15. Use of water-absorbing materials according to one or more of claims 5 to 13 as an absorbent for water and aqueous liquids in absorbent compositions.

16. Use of water-absorbing materials according to claim 14 or 15, characterized in that they are used in hygiene applications.

17. Use of water-absorbing materials according to claim 14 or 15, characterized in that they are used in industrial applications.

18. Use of water-absorbing materials according to one of claims 5 to 13, characterized in that they are used as absorbents for water and aqueous liquids in wipes, paper towels, upholstery, pillows, in absorbent products in the medical sector and in absorbent

Household and industrial products.