Absorbent polymer structure provided with an improved retention capacity and permeability

Translation of description of equivalent WO 2004037903 A2

ABSORBENT POLYMER STRUCTURE WITH IMPROVED

RETENTIONSKÄPAZITÄT AND PERMEABILITY

The invention relates to a method of making an absorbent Polymergebildes, an by this method erhältliches absorbent Polymergebilde, an absorbent Polymergebilde, a composite, a process for producing a composite, a composite obtainable from this process, chemical products beinhaltend the absorbent Polymergebilde or the composite, the use of the absorbent polymer structure or the composite in chemical products, an aqueous solution, a process for preparing the aqueous solution, an aqueous solution obtainable by the process and the use of the aqueous solution for treating the outer portion of an absorbent polymer structure.

Superabsorbents are water-insoluble, crosslinked polymers which are capable, by swelling and formation of hydrogels, absorb large amounts of aqueous liquids, in particular body fluids, preferably urine or blood, and of retaining them under a certain pressure. Because of these characteristic properties, these polymers principally find applications through incorporation into sanitary articles, such as baby diapers, incontinence products or sanitary napkins.

The currently commercially available Superabsorbern is it essentially crosslinked polyacrylic acids or crosslinked starch-acrylic acid graft polymers, in which the carboxyl groups teilweise with sodium or potassium hydroxide are neutralized.

For aesthetic reasons and Umweltaspekten is an increasing trend that Sanitärartikel ever smaller and thinner to make. To ensure a constant total retention capacity of the sanitary products may meet this requirement only by reducing the proportion of voluminous fluff

BESTÄT6GUf \ äGSKOPIE be met. This fall the superabsorbent to other objects in terms of transport and distribution of liquid, which can be summarized as permeability.

Permeability is the term for superabsorbent materials, the ability in the swollen state to transport added fluids and distribute three-dimensional. This process occurs in the swollen superabsorbent gel via capillary transport through interstices between the gel particles. A fluid transport through swollen superabsorber particles themselves follows the laws of diffusion and is a very slow process which plays no role in the distribution of the liquid in the use situation of the sanitary article. When superabsorbent materials that can not accomplish a capillary transportation because of a lack of gel stability, a separation of the particles from one another has been ensured while avoiding the gel blocking phenomenon by embedding these materials in a fiber matrix. In diaper constructions of new generation is in the absorber layer is little or no fiber material to support the liquid transport. The superabsorbers used herein, must therefore have a sufficiently high stability in the swollen state, so the swollen gel has yet a sufficient amount of capillary spaces can be transported by the liquid.

To Superabsorbermaterialien high gel stability to obtain, can einerseits the degree of crosslinking of the polymer to be raised, which inevitably a reduction in the Quellfähigkeit and Retentionsvermögens result has. An optimized combination of different crosslinkers and comonomers, such as in DE 196 46 484 describes the permeability properties can indeed improve, but not on a level that the incorporation of a beispielsweise gegebenenfalls only Superabsorbern existing layer in a Windelkonstruktion allowed. Furthermore methods for treatment of the surface of Polymerpartikeln to improve Superabsorbereigenschaften are used. As the surface treatment linking of the absorbent polymer structure at the surface, comprising contacting the surface with inorganic compounds, or the post-crosslinking of the surface in the presence of inorganic compounds from the prior art are known, for example.

Thus, EP-A-0450923, EP-A-0450922, DE-A-35 23 617, US 5,140,076 and US 4,734,478, the treatment of the surface of absorbent polymers by contacting the surface with inorganic compounds, such as with finely divided silica, during or after postcrosslinking the surface. In addition to increased Absorptionsgeschwindigkeit under pressure is also an increased permeability of the absorbent polymers by this type of surface finishing by achieved.

The DE 35 03 458 describes a process for preparing an improved absorbent resin in which a water-absorbent resin comprising units of a monomer having a carboxyl group in the free acid form or a salt as a Aufbaukomponente desselben contains, in the presence of a powder of a feinteiligen metal oxide can absorb a crosslinking agent and water under stirring and the resulting mixture heated to effect the crosslinking of the resin and the removal of water. Here absorbent resins are obtained with a good Wasserabsoptionsvermögen, at the same time exhibit a good absorption rate.

US 4,535,098 describes a method for increasing the gel strength of not postcrosslinked superabsorbents by swelling of absorbent polymers in the presence of a colloidal inorganic compound such as a silica sol, or by production of an absorbent polymer in the presence of a colloidal inorganic compound. DE 198 05 447 discloses a process for the post-crosslinking of Polyacrylnitrilhydrolysaten with bifunctional compounds and simultaneous immobilization of silica in the surface structure of the superabsorbent polymer. The silicic acid was together with the Vernetzungsmittel in a water / alcohol mixture in contact with the surface brought. By immobilizing the silica to improve the absorbency under load and a reduction of the gel blocking can be achieved.

DE 198 54 575 describes before the addition of alkali salts of silicic acid, during or after the polymerization or partial neutralization of the superabsorbent. Through this surface finishing by an improved permeability achieved, however, mainly by non-swellable additional conditional decreased Rentention of polymers is due.

US 5,147,921 discloses the addition of a silica sol as inert filler that is dispersible in the monomer to be polymerized.

JP 1994-16822 describes the treatment of the surface of absorbent polymers with an inorganic sol. To provide improved processability of the tendency to formation of agglomerates mixture, additionally an organic solvent component is added. As the organic solvent component, for example, mono- and dimethyl ether of diols or diols called itself. After drying, the absorbent polymers will have a higher gel stability, a lower tendency to gel blocking and an improved permeability to water in simple tests without pressure load of superabsorbent.

The prior art describes methods in which inorganic particles are either dry to the Superabsorber be blended or with the help of large partly organic Lösungsmittelmengen in the process of Post-crosslinking are introduced in order to prevent agglomeration of the SAP particles. However, these methods have the drawback that either large amounts of solvent have to be handled, which is undesirable both for economic and for environmental reasons. In addition, superabsorbent polymers tend when mixed with large amounts of liquid to agglomerate, which can seriously affect the workability within a continuous manufacturing process. A simple admixture with inorganic particulate materials brings contrast disadvantages such as segregation or dusting with it. The addition of inorganic additives in aqueous solutions for post-crosslinking itself is difficult because the inorganic particles settle quickly. In addition, can be inorganic dispersions bad dose.

Due to the presence of the prior art offenbarten feinteiligen, inorganic substances it comes to an inhomogeneous distribution of the chemical Nachvemetzers on the surface of the absorbent polymers and accordingly also to an inhomogeneous postcrosslinking. This in turn means that superabsorbent polymers are obtained with an unsatisfactory overall performance, especially in terms of retention and permeability. A homogeneous distribution is containing the chemical cross-linker possible in the described in the prior art method for surface treatment if necessary by the use of large amounts of an aqueous or alcoholic solution.

Generally, the present invention seeks to overcome from the prior art disadvantages arising.

Furthermore, there is an inventive task superabsorbent

Polymers to make available, as Eigenschaftskombination not only high Aufnahmekapazität under pressure, but also the usually opposing properties of high Retentionsvermögens and good Unite permeability in itself to be the requirements of modem hygiene articles, especially diapers, sanitary napkins or Inkontinentsprodukten cater to absorbent polymers. In particular, these polymers possible small amounts of toxic monomers such as acrylamide or acrylonitrile, include that on contact of superabsorbent polymers with body fluids ausgewaschen and, beispielsweise in case of the use of superabsorbent polymers in diapers, in this way, in contact with skin can contact the diaper wearer.

Another, the present object underlying the invention was to provide hygiene products such as diapers, which are compared to the hygiene articles known from the prior art are better able to retain absorbed body fluids, absorbing liquids under pressure and at the Aufhahme liquids this spread as quickly and evenly in the hygiene article.

In addition, is another invention object to provide a method to create, with such absorbent polymers in a simple, continuous manner possible small amounts of organic solvents represented are. In this Herstellungsverfahren should zugesetzte inorganic auxiliaries maximum in small amounts from the superabsorbent polymer to replace that which Polymereigenschaften not nachteilig influence. The solution used in this method of treating the surface of the absorbent polymer should be like a single-phase system can be handled and can be metered uniformly. The coated Superabsorber should during the process in only a slight extent agglomerates form and should easily a continuously arbeitenden Temperungsschritt zugeführt be able.

The above objects are achieved by a process for preparing an absorbent polymer structure (Pa) by treating the outer portion an untreated absorbent polymer structure (Pul), which comprises

Steps of: contacting the outer portion of the untreated absorbent polymer structure (Pul) with an aqueous solution containing at least one chemical crosslinking agent and at least one inorganic compound in dispersed colloidal form;

Heating the absorbent Polymergebildes whose Aussenbereich with the aqueous solution was brought into contact, to a temperature in the range of 40 to 300 ° C, so that, preferably as a result, the Aussenbereich of the absorbent Polymergebildes compared to

Interior is more interconnected and the inorganic compound is at least partially imm outdoors the absorbent polymer structure is obilisiert.

The above objects are also achieved by a method for

Producing an absorbent polymer structure (Pa) by treating the

Outer portion of an untreated with an inorganic compound in dispersed colloidal form absorbent polymer structure (Pu2), comprising the steps of: - contacting the outer portion of the absorbent

Polymer Structure (Pu2) containing an aqueous solution of at least a chemical crosslinking agent and at least one inorganic compound in dispersed colloidal form;

Heating the absorbent Polymergebildes whose Aussenbereich with the aqueous solution was brought into contact, to a temperature in

Range from 40 to 300 ° C so that, preferably whereby the outer region of the absorbent polymer structure is more strongly crosslinked compared to the inner portion and the inorganic compound is immobilized in the outer portion of the absorbent polymer structure at least partially. Absorbent according to the invention Polymergebilde (Pa) are fibers, foams or particles, fibers and particles being preferred and particles are particularly preferred. Absorbent Polymergebilde (Pa) in these forms can be obtained in the as absorbent Polymergebilde (Pul) or (Pu2) correspondingly fibers, foams or particles can be used.

Erfindungsgemäss preferred absorbent polymer fibers are dimensioned so that they in or as a game for textiles and also directly into textiles eingearbeitet be able. It is preferable in the invention that the absorbent polymer fibers have a length in the range of 1 to 500, preferably 2 to 500 and particularly preferably 5 to 100 mm and a diameter in the range of 1 to 200, preferably 3 to 100 and more preferably 5 to 60 denier have.

Erfindungsgemäss particularly preferred absorbent polymer particles are sized so that they have an average particle size according to ERT 420.1-99 in the range from 10 to 3000, preferably 20 to 2000 and particularly preferably 150 to 850 .mu.m.

The method used in the inventive absorbent Polymergebilde (Pul) or (Pu2) is preferably a Polymergebilde, which on (αl) 20 to 99.999 parts by weight -%, preferably from 55 to 98.99 parts by weight -% and more preferably 70 to 98, 79 weight -% of polymerized, ethylenically unsaturated, säuregruppenhaltigen monomers or salts thereof or polymerized, ethylenically unsaturated, a protonated or quaternized nitrogen beinhaltenden monomers, or mixtures thereof, wherein at least ethylenically unsaturated säuregruppenhaltige monomers, preferably acrylic acid, beinhaltende mixtures are particularly preferred, (α2) 0-80 wt .-%, preferably 0 to 44.99 wt .-% and particularly preferably 0.1 wt .-% 44.89 polymerized, monoethylenically unsaturated monomers copolymerizable with (αl) monomers, (Α3) 0.001-5 parts by weight -%, preferably 0.01-3 parts by weight -% and more preferably

0.01-2.5 wt .-% of one or more crosslinking agents, (α4) 0-30 wt .-%, preferably 0-5 wt .-%, and particularly preferably 0.1-5

Weight -% of a wasserlöslichen polymers, and (α5) 0-20 parts by weight -%, preferably 0 to 10 weight -% and more preferably 0.1 -

8 wt .-% of one or more auxiliaries is based, wherein the sum of the

Weight amounts to (α5) wt .-% is (αl) 100th

The monoethylenically unsaturated, acid group-containing monomers (αl) can be partially or fully, preferably partially neutralized. The monoethylenically unsaturated, säuregruppenhaltigen monomers to at least 25 mol%, more preferably at least 50 mol% and more preferably 50-80 mol% neutralized. In this context, reference is made to DE 195 29 348, the disclosure of which is hereby incorporated by reference. The neutralization can be carried out partially or completely after the polymerization. Furthermore, the neutralization with alkali metal,

Alkaline earth metal hydroxides, ammonia and carbonates and bicarbonates. In addition, any further base is conceivable which forms a water soluble salt with the acid. A mixed neutralization with different bases is also conceivable. Preference is given to neutralization with ammonia and

Alkali metal hydroxides, more preferably with sodium hydroxide and with

Ammonia.

Furthermore may predominate in a polymer the free acid groups, so that this polymer has a lying in the acid range pH. This acidic water-absorbing polymer can be prepared by a polymer with free basic groups, preferably amine groups, which is basic compared to the acidic polymer are at least partially neutralized. These polymers are described in the literature as, Jtfixed-Bed Ion-Exchange Absorbent Polymers "(MBIEA polymers) and are among others in the WO 99/34843 offenbart. The disclosure of WO 99/34843 is hereby introduced as a reference and is considered thus part of the disclosure. Usually MBIEA polymers represent a composition that contain one hand basic polymers that are able to exchange anions, and on the other hand, an acidic compared to the basic polymer polymer that is capable of exchanging cations. The basic polymer has basic groups and is typically obtained by the polymerization of monomers which carry basic groups or groups that can be converted into basic groups. These monomers are, above all, to those which contain primary, secondary or tertiary amines or the corresponding phosphines or at least two of the above functional groups. This group of monomers includes in particular ethyleneamine, allylamine, diallylamine, 4- aminobutene, Alkyloxycycline, vinylformamide, 5-aminopentene, carbodiimide, formaldacine, melamine and the like, and secondary or tertiary amine derivatives.

The monoethylenically unsaturated, acid group-containing monomers (αl) can be partially or fully, preferably partially neutralized. The monoethylenically unsaturated, acid group-containing monomers at least 25 mole%, more preferably at least 50 mol% and moreover preferably 50-90 mol%. The neutralization of the monomers (αl) can also be effected after the polymerization. Furthermore can be carried out the neutralization with alkali metal, alkaline earth metal hydroxides, ammonia and carbonates and bicarbonates. In addition, any further base is conceivable which forms a water soluble salt with the acid. A mixed neutralization with different bases is also conceivable. Preferably, the neutralization with ammonia or with alkali metal, more preferably with sodium hydroxide or with ammonia.

Preferred monoethylenically unsaturated, acid-functional monomers (αl) are acrylic acid, methacrylic acid, ethacrylic acid, α-chloro acrylic acid, α-

Cyanoacrylic, ß-methyl acrylic acid (crotonic), α-phenylcyanoacrylic, ß Acryloxy, sorbic acid, α-chloro sorbic acid, 2 '

Methylisocrotonsäure, cinnamic acid, p-chloro cinnamic acid, beta-stearyl acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, tricarboxyethylene and maleic anhydride, acrylic acid and M thacryl acid hf.ςrmde.r <. nnH acrylic acid. moreover are bevorπigf

Besides these carboxylatgruppehhaltigen monomers are monoethylenically unsaturated monomers säuregruppenhal strength (αl) further ethylenically unsaturated sulfonic acid or ethylenically unsaturated phosphonic acid monomers.

Ethylenically unsaturated sulfonic acid monomers are allylsulfonic or aliphatic or aromatic vinyl or acrylic or methacrylic sulfonic acids. As aliphatic or aromatic vinylsulfonic acids vinylsulfonic, 4-vinylbenzyl, vinyl toluene and styrene are preferred. When acrylic or Methacrylsulfonsäuren are sulfonic foethyl (meth) acrylate, sulfopropyl (meth) acrylate, 2-hydroxy-3 -methacryloxypro- pylsulfonsäure and 2-acrylamido-2-methylpropanesulfonic acid are preferred.

Furthermore are ethylenically unsaturated phosphonic acid, such as vinylphosphonic acid, allylphosphonic, vinylbenzylphosphonic,

acrylamidoalkylphosphonsäuren (meth) Acrylamidoalkyldiphosphonsäuren, phosphonomethylated vinyl amines and (meth) acrylphosphonsäurederivate preferred.

Ethylenically unsaturated, a protonated nitrogen-containing monomers (αl) are dialkylaminoalkyl (meth) acrylates in protonated form, beispielsweise dimethylaminoethyl (meth) acrylate Hydrochlorid or Dimefhyla-minoethyl (meth) acrylate Hydrosulfat, and dialkylaminoalkyl (meth) acrylamides in the protonated form, beispielsweise dimethylaminoethyl (meth) acrylamide-hydro-chloride or dimethylaminoethyl (meth) acrylamide Hydrosulfat preferred. Ethylenically unsaturated, containing a quaternized nitrogen monomers (αl) are dialkylammoniumalkyl (meth) acrylates in quaternized form, for example, trimethyl ammonium ethyl (meth) acrylate methosulfate or di- methylethylammoniumethyl (meth) acrylate-ethosulfate as well as (meth) acrylamidoalkyldialkylamines in quaternized form , for example

(Meth) acrylamidopropyltrimethylammonium and (meth) acrylamidopro- pyltrimethylammoniumsulfat preferred.

It is preferable in the invention that component (αl) to at least 50 wt .-%, preferably at least 70 wt .-% and more preferably comprises at least 90 wt .-% of monomers containing carboxylate groups. It is erfindungsgemäß particularly preferred that the component (αl) of at least 50 parts by weight -%, preferably at least 70 wt -% of acrylic acid is, preferably at least 20 mole%, particularly preferably at least 50 mol% neutralized is.

Preferred monoethylenically unsaturated monomers copolymerizable with (αl) monomers (α2) acrylamides and methacrylamides are preferred.

Possible (meth) acrylamides are, in addition to acrylamide and methacrylamide, alkyl substituted (meth) acrylamides or aminoalkyl-substituted derivatives of (meth) acrylamide such as N-methylol (meth) acrylamide, N, N-dimethylaniline mino (meth) acrylamide, dimethyl (meth ) acrylamide or diethyl (meth) acrylamide. Possible vinylamides are for example N-vinylamides, N-vinylformamides, N- vinylacetamides, N-vinyl-N-Methylacetamide, N-vinyl-N-methylformamide, vinylpyrrolidone. Among these monomers acrylamide is particularly preferred.

Furthermore, as monoethylenically unsaturated with (αl) copolymerizable monomers (α2) are preferably water-dispersible monomers. As water-dispersible monomers are acrylic esters and methacrylic esters, such as methyl methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate or-Bu tyl (meth) acrylate, and Methylpolyethylenglykol (meth) acrylate,

Methylpolyethylene, vinyl acetate, styrene and isobutylene are preferred.

Erfindungsgemäß preferred crosslinker (α3) are compounds containing at least two ethylenically unsaturated groups within one molecule include (cross-linker I), compounds containing at least two functional groups which with funktioneilen groups of the monomers (αl) or (α2) in a Kondensationsreaktion ( = Kondensafionsvernetzer), in a Additionsreaktion or in a Ringöffnungsreaktion respond to (cross-linker class II), compounds containing at least one ethylenically unsaturated group and at least one functional group which can react with functional groups of the monomers (αl) or (α2) in a Kondensationsreaktion, in a Additionsreaktion or in a Ringöffnungsreaktion can react (cross-linker class III), or polyvalent Metallkationen (cross-linker class IV). Here, by the compounds of the cross-linker I crosslinking of the polymers by the free radical polymerization of the ethylenically unsaturated groups of the cross with the monoethylenically unsaturated monomer (αl) or (α2) is achieved, while the compounds of cross-linker II and the polyvalent Metallkationen the cross-linker IV crosslinking of the polymers by Kondensationsreaktion of the functional groups (cross-linker II) or by interaction of the polyvalent elektrostatische Metallkations (cross-linker IV) with the functional groups of the monomers (αl) or (α2) is achieved. In the compounds of cross-linker class III accordingly, crosslinking of the polymer by radical polymerization of the ethylenically unsaturated group and by condensation reaction between the functional group of the crosslinking agent and the functional groups of the monomers (αl) or (α2). Preferred compounds of the cross-linker I are poly (meth) acrylate or poly (meth) acrylamides, the beispielsweise by the reaction of a polyol such as beispielsweise Ethylenglykol, Propylenglykol, trimethylolpropane, 1,6-hexanediol, glycerol, pentaerythritol, or Polypropylenglykol Polyethylenglykol, an amino alcohol , a polyalkylenepolyamine, such as diethylenetriamine or triethylenetetramine beispielsweise, or an alkoxylated polyol with acrylic acid or methacrylic acid be obtained. As compounds of the cross-linker class I are are polyvinyl, poly (mefh) allyl compounds, (meth) acrylate of a Monovinylverbindung or (meth) acrylate of a mono (meth) allyl compound, preferably of the mono (meth) allyl compounds of a polyol or an aminoalcohol. In this context, reference is made to DE 195 43 366 and DE 195 43 368th The disclosures of which are hereby incorporated by reference and are thus part of the disclosure. As compounds of the cross-linker class I had an example called Alke-nyldi (mefh) acrylates, beispielsweise ethylene glycol di (meth) acrylate, 1,3-propylene-glycol di (meth) acrylate, 1 0.4-butylene glycol (meth) acrylate, 1, 3 - Butylengly-KOLDI (mefh) acrylate, 1 0.6-hexanediol di (meth) acrylate, 1, 10-decanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, 1, 18-Octadecandioldi (meth) acrylate, Cyclops- tandioldi (meth) acrylate, neopentyl glycol di (meth) acrylate, methylenebis (meth) acrylate or pentaerythritol di (meth) acrylate, Alkenyldi (meth) acrylamides, such as N-methyl di (meth) acrylamide, N, N'-3-Methylbutylidenbis (meth) acrylamide, N, N'-(1 .2-di-hydroxyethylene) bis (meth) acrylamide, N, N'-hexamethylene bis (meth) acrylamide or N, N^*Methylenebis (meth) acrylamide, polyalcohols xydi (meth) acrylates, such as diethylene glycol di (meth) acrylate, triethylene glycol di (mefh) acrylate, tetraethylene glycol di (meth) acrylate, dipropylene KOLDI (meth) acrylate, tripropylene glycol di (meth) acrylate or Tetrapropylengly- KOLDI (meth) acrylate, bisphenol A di (meth) acrylate, ethoxylated bisphenol-A- di (meth) acrylate, Benzylidindi (meth) acrylate, 1, 3-di (meth) acryloyloxy-2-propanol, hydroquinone (meth) acrylate, di (meth) acrylate esters of oxyalkylated preferably having 1 to 30 moles of alkylene oxide per hydroxyl group, preferably ethoxylated Trimefhylolpropans, Thioethylenglykoldi (meth) acrylate,

Thiopropylenglykoldi (meth) acrylate, Thiopolyethylenglykoldi (meth) acrylate,

Thiopolypropylenglykoldi (meth) acrylate, divinyl ether, for example, 1, 4-butanediol, divinyl, for example divinyl, alkadienes, such as butadiene or 1,6-hexadiene, divinylbenzene,

Di (meth) allyl compounds, such as di (meth) allyl phthalate or di (meth) allylsuccinat, homo- and copolymers of

Di (meth) allyldimethylammonium chloride and homo- and copolymers of diethyl (meth) allylaminomethyl (meth) acrylatammoniumchlorid, vinyl (meth) acrylic compounds, beispielsweise vinyl (meth) acrylate, (meth) allyl (meth) acrylic compounds, beispielsweise (meth) allyl (meth) acrylate, with 1 to 30 moles of ethylene oxide per hydroxyl ethoxylated (meth) allyl (meth) acrylate, di (meth) allyl ester of polycarboxylic, allyl maleate, for example, di (meth), di (meth) allylfumarat, di ( meth) allylsuccinat or di (meth) allylterephthalat, Ver-compounds having 3 or more ethylenically unsaturated, radically polymerisi newable groups such beispielsweise glycerol (meth) acrylate, (meth) acrylate ester of having preferably 1 to 30 mol ethylene oxide per hydroxyl oxyethylated glycerol, trimethylolpropane (mefh) acrylate, tri (meth) acrylate ester preferably oxyalkylated of 1 to 30 moles of alkylene oxide per hydroxyl group, preferably ethoxylated trimethylolpropane, Trimethacrylamid,

(Meth) allylidendi (meth) acrylate, 3-allyloxy-1 .2-propanediol di (meth) acrylate,

Tri (meth) allylcyanurat, tri (meth) allyl isocyanurate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, (meth) acrylic acid ester of having preferably 1 to 30 moles of ethylene oxide per hydroxyl group oxyethylated pentaerythritol, tris (2-hydroxyethyl) isocyanurate tri (meth ) acrylate, trivinyl trimellitate, tri (meth) allylamine, di (meth) allylalkylamine, allylmethylamine example, di (meth)

Tri (meth) allyl phosphate tetra (meth) allylethylendiamin, poly (meth) allyl ester, tetra (meth) allyloxiethan or tetra (meth) allylammoniumhalide.

As the compound of cross-linker, preferred are compounds II containing at least two functional groups which in a Kondensationsreaktion (= Condensation) may in an addition reaction or in a ring opening reaction with the functional groups of the monomers (αl) or (α2), preferably with acid groups of the monomers (αl), respond. These functional groups of the compounds of cross-linker class II are preferably alcohol, amine, aldehyde, glycidyl, isocyanate, carbonate or epichloro.

As the compound of cross-linker class II are mentioned as examples polyols beispielsweise Ethylenglykol, Polyethylenglykole such as diethylene glycol, glycol-Triefhy and Tetraethylenglykol, Propylenglykol, Polypropylenglykole as dipropylene glycol, tripropylene or Tetrapropylenglykol, 1,3-butanediol, 1 0.4-butanediol, 1,5 - pentanediol, 2,4-pentanediol, 1 0.6-hexanediol, 2,5-hexanediol, glycerol, polyglycerol, trimethylol propane, polyoxypropylene, oxyethylene-oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid ester, pentaerythritol, polyvinyl alcohol and sorbitol, amino alcohols, beispielsweise Ethanolamin , diethanolamine, triethanolamine or propanolamine, polyamine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or pentaethylenehexamine, polyglycol diglycidyl ether compounds such as ethylene glycol, polyethylene glycol diglycidyl ether, glycerol diglycidyl, glycerol polyglycidyl, Pentareritrit- polyglycidyl, propylene glycol, Polypropylenglykoldiglycidyl- ether, neopentyl glycol, hexanediol, panpolyglycidylether trimethylolpropane, sorbitol polyglycidyl ether, phthalic acid diglycidyl ester, adipic pinsäurediglycidylether, l, 4-phenylene-bis (2-oxazoline), glycidol, Poiyisocyanate, preferably diisocyanates, such as 2,4-toluene diisocyanate and

Hexamethylene diisocyanate, polyaziridine compounds such as 2,2-bishydroxy-methyl butanol-tris [3 - (l-aziridinyl) propionate], 1,6-Hexamefhylendiefhylen-urea, and diphenyl methane-bis-4, 4'-N, N'-diethylenhamstoff, haloepoxides beispielsweise epichloro-and epibromohydrin, and α-methylepichlorohydrin, alkylene carbonates such as l .3-dioxolan-2-one (ethylene carbonate), 4-methyl-l .3-dioxo-lan-2-one (propylene carbonate), 4,5-dimethyl -l, 3-dioxolan-2-one, 4,4-dimethyl-l, 3- dioxolan-2-one, 4-Efhyl-l, 3-dioxolan-2-one, 4-hydroxymethyl-l, 3-dioxolan-2-one, l, 3-dioxan-2-one, 4-methyl-l, 3-dioxan-2-one, 4,6-dimethyl-l, 3-dioxan-2-one, 1,3-dioxolan-2-one, poly-l, 3-dioxolan-2-one, amines such as condensation products polyquaternary of dimethylamines and epichlorohydrin. When compounds of Ver-netzerklasse II are further Polyoxazolines as 1 0.2-ethylenebisoxazoline, crosslinking agents with silane groups such as γ-glycidoxypropyltrimethoxysilane and γ-AminoPro-pyltrimethoxysilan, oxazolidinones such as 2-oxazolidinone, bis- and poly-2-oxazolidinones and diglycol silicates preferably ,

Preferred compounds of class III are hydroxyl or amino group-containing esters of (meth) acrylic acid, such as 2-hydroxyethyl (meth) acrylate, and hydroxyl or amino-containing (meth) acrylamides, or

Mono (meth) allyl compounds of diols.

The polyvalent metal cations of cross-linker class IV are preferably derived from mono- or polyvalent cations from the singly charged in particular from alkali metals such as potassium, sodium, lithium, with lithium being preferred. Preferred divalent cations are derived from zinc, beryllium, alkaline earth metals such as magnesium, calcium, strontium, magnesium being preferred. Further applicable higher valent cations are cations of aluminum, iron, chromium, manganese, titanium, zirconium and other transition metals as well as double salts of such cations or mixtures of said salts. Preference is given to aluminum salts and alums and their various hydrates such. B. A1C1₃ x 6H₂O, NaA (SO₄)₂ 12 H₂O, KAI (SO₄)₂ x 12 H₂O or Al₂(SO₄)₃^χl4-18 H₂O used.

Particular preference Al₂(SO₄)₃ and its hydrates used as crosslinkers of crosslinking class IV.

Preferred absorbent Polymergebilde (Pul) or (Pu2) are Polymergebilde that by crosslinkers of the following cross-linker classes or by crosslinkers of the following combinations of cross-linker classes linked are: I, II, III, IV, I II, I III, I IN, I II III, I, II, IV, III IV I, II III IV, II or III IV IN. The above combinations of cross-linker classes each represent a preferred embodiment of crosslinkers of a polymer dar.

Further preferred Ausführungsformen the absorbent Polymergebilde (Pul) or (Pu2) are Polymergebilde represented by any of the above mentioned cross-linkers of cross-linker classes I linked are. Among these water-soluble crosslinkers are preferred. In this context, Ν, Ν'-Mefhylenbisacrylamid, polyethylene glycol di (meth) acrylates, Triallylmethylammonium chloride, tetraallylammonium chloride and with 9 moles of ethylene oxide per mole of acrylic acid produced Allylnonaethylenglykolacrylat particularly preferred.

As wasserlösliche polymers (α4) can in the inventive absorbent Polymergebilden (Pul) or (Pu2) wasserlösliche polymers, such as partially or fully saponified polyvinyl alcohol, polyvinylpyrrolidone, starch or Stärkederivate, polyglycols or polyacrylic acid, preferably polymerized be. The molecular weight of these polymers is not critical as long as they are water soluble. Water-soluble polymers are starch or starch derivatives or polyvinyl alcohol. The water soluble polymers, such as polyvinylalcohol, may also serve as graft basis for the monomers to be polymerized.

Auxiliaries (α5) (Pul) or (Pu2) may be contained preferably adjusting agents, surface active agents, odor binders, fillers or antioxidants in the used in the inventive absorbent polymer structures.

It is inventively particularly preferred that the absorbent polymer structure (Pul) or (Pu2) is a cross-linked polyacrylate in particulate form, which by polymerization ion of an acrylic acid and optionally a above-mentioned crosslinking agents in aqueous solution, beinhaltend the acrylic acid in an amount in a range of 5 to 80 parts by weight -%, preferably 10 to 70 parts by weight -% and more preferably 20 to 50 weight -%, based on the weight of the aqueous solution, and subsequent comminution of the resultant polymer gel, drying the comminuted gel and optionally further grinding of the dried polymer was obtained. The thus obtained absorbent Polymergebilde are preferably formed by a Wassergehalt from 0.5 to 25 parts by weight -%, preferably from 1 to 10 weight -% in.

In a preferred embodiment of the method the absorbent polymer structure based (Pul) or (Pu2) at least 50 wt .-%, preferably at least 75 wt .-% and more preferably wt .-% based on at least 90 to acrylic acid, the preferably at least 20 mole%, particularly preferably at least 50 mol% neutralized is.

It is also preferred that the absorbent polymer structure (Pul) or (Pu2) is not based on polyacrylonitrile emulsions. It is preferred that the absorbent Polymergebilde (Pul) or (Pu2) less than 37 mol%, particularly preferably less than 20 mole%, more preferably less than 10 mol% and further even more preferably about less than 5 mole% based on acrylamide and / or acrylonitrile monomers. It is in this context also preferred that the absorbent polymer structure (Pul) or (Pu2) a proportion of soluble, to acrylonitrile and / or acrylamide-based monomers monomer or polymer of less than 1,000 ppm, more preferably less than 500 ppm, moreover preferably less than 100 ppm, and furthermore, exhibit even more preferably of less than 10 ppm.

From the above-mentioned monomers and crosslinkers, the absorbent polymer structure (Pul) or (Pu2) leaves by various polymerization manufacture. For example, in this connection bulk polymerization, which is preferably carried out in kneading reactors such as extruders, solution polymerization, spray polymerization, inverse emulsion polymerization and inverse suspension. Solution polymerization is preferably carried out in water as solvent. The solution polymerization can be continuous or discontinuous. a broad spectrum of possible variations with respect to reaction conditions such as temperatures, type and amount of initiators and the reaction solution is apparent from the prior art. Typical processes are described in the following patents: US 4,286,082, DE 27 06 135, US 4,076,663, DE 35 03 458, DE 40 20 780, DE 42 44 548 DE 43 23 001, DE 43 33 056. DE 44 18 818th the disclosures of which are hereby incorporated by reference and are thus part of the disclosure.

Another possibility for producing the absorbent Polymergebilde (Pul) or (Pu2) is initially uncrosslinked, particularly linear polymers, preferably by radical route of the aforementioned monoethylenically unsaturated monomers (αl) and (α2) to produce and then with crosslinking reagents (α3), preferably those of classes II and IV to implement. This variant is preferably used when the polymer structures will first be processed in shaping processes, for example into fibers, films or other flat structures such as fabrics, knitted fabrics, webs or fleeces, and cross-linked in this form.

The polymerization is generally customary manner, by an initiator. As initiators for initiating polymerization can all radicals under the polymerization initiators are used, which are customarily used in the production of superabsorbers. Initiation of the polymerization by the action of electron beams on the polymerizable aqueous mixture is also possible. However, the polymerization can also be in the absence of initiators of the abovementioned kind, by Action energiereicher radiation in the presence of Photoinitiatoren be triggered. Polymerization initiators may be dissolved or dispersed in a solution of inventive monomers or. Possible initiators are all known to those skilled decompose into free radicals compounds. These include in particular peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and redox catalysts. the use of water-soluble catalysts is preferred. In some cases it is advantageous to use mixtures of various polymerization initiators. Among these mixtures, those from Wasserstofφeroxid and sodium or potassium, which can be used in any conceivable quantity ratio. Suitable organic peroxides are acetylacetone,

Methyl ethyl ketone peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-amyl perpivalate, t-butyl perpivalate, t-Butylpemeohexonat, t-butyl isobutyrate, t-butyl per-2-ethylhexenoat, t-butyl perisononanoate, t-Butylpermaleat, t-butyl perbenzoate, t-butyl-3, 5,5-tri-methylhexanoate and Amylperneodekanoat. Other suitable polymerization initiators are preferred: azo compounds such as 2,2'-azobis (2-amidinopropane) dihydrochloride, azo-bis-amidinopropane dihydrochloride, 2,2 '- azobis (N, N-dimethylene) isobutyramidine dihydrochloride , 2- (carbamoylazo) isobutyronitrile and 4,4'-azobis- (4-cyanovaleric acid). The compounds mentioned are used in customary amounts, preferably in a range of 0.01 to 5, preferably from 0.1 to 2 mol%, based in each case on the amount of monomers to be polymerized.

The redox catalysts contain as oxidic component at least one of the above-mentioned compounds and the reducing component preferably ascorbic acid, glucose, sorbose, mannose, ammonium or Alkalimetall bisulfite, sulfate, thiosulfate,-hyposulfite or sulfide, Metallsalze, such as iron-II ions or Silberionen or sodium hydroxymethylsulfoxylate. Preferably, the reducing component of the redox catalyst ascorbic acid or sodium used. Based on the amount of monomers in the polymerization is l lO^"5 to 1 mol% of the reducing component of the redox catalyst and lxlO^"5 used to 5 mol% of the oxidizing component of the redox catalyst. Instead of the oxidizing component of the redox catalyst, or in addition to this, one or more, preferably water-soluble azo compounds are used.

When the polymerization is initiated using high energy radiation, are usually used photoinitiators as initiator. Here, it is beispielsweise so-called α-splitters, H-abstracting systems or else azides act. Examples of such initiators are benzophenone derivatives such as Michlers's ketone, phenanthrene derivatives, fluorene derivatives, Anthracite-quinone derivatives, thioxanthone derivatives, coumarin derivatives, benzoin ethers and derivatives thereof, azo compounds such as the aforementioned radical generator, substitution-ated hexaarylbisimidazoles or acylphosphine oxides. Examples of azides are: 2- (N, N-dimethylamino) ethyl-4-azidocinnamat, 2- (N, N-dimethylamino) azidonaphthylketon -efhyl-4-, 2- (N, N-dimethylamino) ethyl-4 -azidobenzoate, 5-azido-l - naphthyl-2'-(N, N-dimethylamino) ethyl sulfone, N-(4-Sulfonylazidophe-nyl) maleimide, N-acetyl-4-sulfonylazidoanilin, 4-Sulfonylazidoanilin, 4-azido- aniline, 4-Azidophenacylbromid, p-azidobenzoic acid, 2,6-bis (p-azidobenzyli-den) cyclohexanone and 2,6-bis (p-azidobenzylidene)-4-methylcyclohexanone. The photoinitiators, if used, typically in amounts of from 0.01 to 5 wt .-%, based on the monomers to be polymerized.

Preferably erfindungsgemäß a redox system consisting of Wasserstofφeroxid, sodium and ascorbic acid used. According to the invention generally azo compounds are preferred as initiators, azo-bis-amidinopropane dihydrochloride is particularly preferred. In general, the polymerization is initiated with the initiators in a temperature range of 30 to 90 ° C. The drying of the polymer gel to a Wassergehalt from 0.5 to 25 parts by weight -%, preferably from 1 to 10 weight -% at temperatures typically in the range of 100 to 200 ° C.

In a preferred embodiment the invention in

Method used, absorbing Polymergebilde (Pul) or (Pu2) at least one of the following properties (ERT = EDANA Recommended

Test): (A) the maximum absorption of 0.9 wt .-% he NaCl solution according to ERT

440.1-99 is in a range of at least 10 to 1000, preferably from

15 to 500 and particularly preferably from 20 to 300 g / g,

(B) with 0.9 part by weight -% he aqueous NaCl extractable fraction in accordance with ERT 470.1-99 is less than 30, preferably less than 20 and more preferably less than 10 weight -%, based on the absorbent Polymergebilde ( Pul) or (Pu2)

(C) the bulk density in accordance with ERT 460.1-99 is in the range of 300 to 1000, preferably 310-800 and more preferably 320-700 g / 1,

(D) the pH value according to ERT 400.1-99 of 1 g of the absorbent polymer structure (Pul) or (Pu2) in 1 1 water ranges from 4 to

10, preferably from 5 to 9 and particularly preferably from 5.5 to 7.5,

(E) the CRC value according to ERT 441.1-99 is in the range of 10 to 100, preferably 15 to 80 and particularly preferably 20 to 60 g / g.

Resulting from the above properties resulting Eigenschaftskombinationen of two or more of these properties each preferred Ausführungsformen the inventive method dar. Furthermore as inventive embodiments are particularly preferred method, in which the absorbent Polymergebilde (Pul) or (Pu2) is referred to as letters or Buchstabenkombinationen illustrated features or Eigenschaftskombinationen shows: A, B, C, D, e, AB, AC, AD, AE, ABC, ABD, ABE, ACD, ACE, ADE, ABCD, ABCE, ABDE, ACDE, ABCDE.

The contacting of absorbiererenden Polymergebildes (Pul) or (Pu2) with the aqueous solution is in the process of the invention preferably by thorough mixing of the aqueous solution with the absorbent Polymergebilde (Pul) or (Pu2). The aqueous solution is preferably substantially free of organic solvents, in particular free of polyhydric alcohols and polyalkylene glycol ethers, more preferably free of Diethylenglycolmonomethylefher and 1,3-butanediol. It is particularly preferred in this context that under an aqueous solution, a solution is understood the weight .-%, more preferably at least 60 wt .-%, more preferably at least 70 wt .-% and in addition to at least 50 even more preferably at least 90 wt .-%, based in each case based on the total amount of all existing in the aqueous solution, room temperature liquid components to water.

It may be containing a priori present in the aqueous solution, the inorganic compound in dispersed colloidal form of chemical crosslinkers. However, it is also possible that the chemical crosslinking agent, and the colloidal inorganic compound separately, but preferably zeitgleich with the absorbent Polymergebilde (Pul) or (Pu2) are brought into contact. In this case, preferably, two separate solutions, one of which is the chemical crosslinking agent and the other inorganic compound in dispersed colloidal form containing, preferably simultaneously with the absorbent Polymergebilde (Pul) or (Pu2) are mixed, but a homogeneous distribution of the chemical crosslinker and the inorganic compound must be ensured in colloidal form.

Suitable Mischaggregate for applying the components For example, the Patterson-Kelley mixer, DRAIS Turbulenzmischer, Lodige, Ruberg Mixers, screw mixers, pan mixers and fluidized bed mixers as well as continuously operating vertical mixers, in which the polymer structure is mixed at a rapid frequency using rotating knives (Schugi mixer). The absorbent Polymergebilde (Pul) or (Pu2) is in the process of the invention preferably with a maximum of 20 weight -%, particularly preferably at most 15 weight -%, moreover preferably with at most 10 weight -%, moreover even more preferably with not more than 5 wt .-% water brought and even most preferably less than 3 wt .-%, in each case based on the weight of the absorbent polymer structure (Pul) or (Pu2) in contact.

In one use of absorbent Polymergebilden (Pul) or (Pu2) in the form of preferably spherical particles is erfindungsgemäß further preferred that the contacting takes place such that only the Aussenbereich, but not the inner region of the particulate absorbent Polymergebilde with the inorganic compound in dispersed colloidal form is brought into contact are. In this context, the most Aussenbereich the Polymergebilde preferably that region understood the characterized is that the distance of each lying in this portion Raumpunktes from the center of the particle is at least 50%, more preferably at least 75%, more preferably at least 90% and above even more preferred at least 95% of the radius of the particulate absorbent polymer structure. The thus generated inhomogeneous immobilization of colloidal inorganic compound on the Polymergebilden is erfindungsgemäß achieved by dry Polymergebilde with the aqueous solution is brought into contact to be and also just as a small amount of water used to be that it is only in Aussenbereich the absorbent Polymergebilde to an absorption of aqueous liquid comes. It is in the inventive method further preferred that at least 30 wt -%, particularly preferably at least 60 wt -% and more preferably at least 90 wt -% of colloidal inorganic compound a Partikelgröße in the range of 1 to 100, preferably from 5 to 80 and even more preferably from 6 to 50 nm.

The inorganic compound is according to the inventive method preferably in an amount of 0.001 to 10 weight -%, particularly preferably from 0.01 to 5 parts by weight -% and more preferably from 0.05 to 1.5 parts by weight -%, based on the absorbent polymer structure (Pul) or (Pu2), with the absorbent polymer structure (Pul) or (Pu2) contacted.

As the inorganic compound, all water-insoluble inorganic compounds used are from which stable, colloidal, preferably single phase, aqueous solutions obtained can, which at 20 ° C and Normaldruck over a period of at least 6 hours, preferably at least 24 and particularly preferably at least 72 hours to through to 6 months, no phase separation, such as settling of a solid inorganic precipitate FIG.

Under a colloidal solution is preferably a solution understood that particles with a Partikeldurchmesser in a range of 100-1000 A (10^" until 10^" cm) contains. These solutions have the property of a solution by the skillful Lichtstrahl in all directions to spread, so that the transition of Lichtstrahls by the colloidal solution can be traced can (Tyndall effect, see Hollemann-Wiberg, Lehrbuch inorganic chemistry, 91.-100 ed., de Gruyter- Verlag, page 765).

Particularly preferred colloidal inorganic compound are in the process of this invention polysilicic beinhaltende particles used.

A colloidal solution containing such particles (silica sol) can for example be obtained by careful acidification of alkaline hydrolysis as a result of reacting sodium silicate solutions or by dissolving molecular silicic acid in water and potentially subsequent stabilization of the resulting colloidal dispersion. The exact production of such silica sols is known in the art and is for example in Jander- Blasius, J ehrbuch analytical and preparative inorganic chemistry ,, S. Hirzel Verlag, Stuttgart, described.

In addition to the colloidal silica according to the invention are further iron (III) oxide hydrate sols, tin (IV) oxide hydrate sols or

Silver halides, particularly Silberchlorid based sols as colloidal inorganic compound particularly preferred.

Among chemical crosslinkers, which are included in the process of the invention in the aqueous solution, preferably compounds which, having at least two functional groups which can react with functional

Groups of a polymer in a condensation reaction

(= Condensation), one in an addition reaction or in

Ringöffnungsreaktion react can or polyvalent Metallkationen which means elektrostatischer interaction between the polyvalent

Metallkation and the functional groups of a polymer, crosslinking of the

Polymers allow. As chemical crosslinkers for postcrosslinking the

Outer portion of the absorbent polymer structure (Pul) or (Pu2) - also

called "postcrosslinker" - are in the process of the invention, those which are related to the crosslinkers (α3) as crosslinkers the

Cross-linker classes were called II and IV.

Among these compounds are particularly preferred as crosslinker

Condensation cross such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerol, polyglycerol, propylene glycol, diethanolamine,

Triethanolamine, polyoxypropylene, Oxyefhylen-oxypropylene block copolymers, Sorbitan fatty acid esters, polyoxyethylene Trimefhylolpropan, pentaerythritol, polyvinyl alcohol, sorbitol, l, 3-dioxolan-2-one (ethylene carbonate), 4-methyl-1, 3-dioxolan-2-one (propylene carbonate), 4,5-dimethyl-l, 3-dioxolan-2-one, 4,4-dimethyl-l .3-dioxolane-2-one, 4-ethyl-l .3-dioxolane-2-on, 4-hydroxymethyl-l .3-dioxolan-2- one, l .3-dioxane-2-one, 4-methyl-l .3-dioxane-2-one, 4,6-dimethyl-l .3-dioxane-2-one, l .3-dioxolane-2- on poly-l .3-dioxolan-2-one.

Particularly preferred ethylene carbonate is used as a post-crosslinking agent.

The post-crosslinking agent in the inventive process preferably in an amount ranging from 0.01 to 30, more preferably 0.1 to 20 and even more preferably from 0.3 to 5 wt -%, based on the absorbent Polymergebilde (Pul) or (Pu2) is used.

After the chemical crosslinking agent and the aqueous solution containing brought the inorganic compound with the absorbent polymer structure (Pul) or (Pu2) contacting the Nachvemetzungsreaktion occur in the process according to the invention by heating the absorbent polymer structure at temperatures ranging from 40 to 300 ° C, preferably from 80 to 250 ° C and particularly preferably from 150 to 220 ° C. The optimum time period for additional heating can be readily determined for individual crosslinker and dispersed colloidal inorganic compounds. She is limited if the desired property profile of the superabsorbent is destroyed as a result heat damage. The thermal treatment can be carried out in conventional dryers or ovens, for example may be mentioned rotary kilns, fluidized bed dryers, plate dryers, paddle dryers or infrared dryers.

It is erfindungsgemäß preferred that due to the thermal treatment of the absorbent Aussenbereich Polymergebildes more highly crosslinked than the

Interior and that the thermal treatment the inorganic Compound is immobilized at least partially outdoors. Furthermore, it is preferred in this context, that the radius of Aussenbereiches is smaller than the value of the radius of the dreifache Innenbereiches.

In another embodiment of the inventive method, the Aussenbereich the absorbent Polymergebilde before or after, preferably after, the contacting with the aqueous solution beinhaltend the chemical crosslinking agent and the inorganic compound in colloidal form with a compound containing Al³⁺brought ions into contact. In this case, it is preferred that the compound containing Al ions in an amount in a range of 0.01 to 30 parts by weight -%, particularly preferably in an amount in a range of 0.1 to 20 parts by weight -% and moreover preferably in an amount in a range of 0.3 to 5 wt .-%, each based on the weight of absorbent polymer structure is brought into contact with the polymer structures.

The contacting of Aussenbereiches the absorbent Polymergebilde with the AI-ion-containing compound is preferably carried out by the fact that the absorbent Polymergebilde (Pa) with the compound under dry conditions mixed is, or the fact that the absorbent Polymergebilde (Pa) with a fluid comprising a Solvents, preferably water, water-miscible organic Solvents such as methanol or ethanol or mixtures of at least two of them, as well as the Al³⁺Ions containing compound are brought into contact, wherein the contacting is preferably by spraying the polymer with the fluid and mixing takes place. In this context, it is further preferred that the bringing of the absorbent polymer structure (Pa) with the fluid comprising contacting the Al³⁺occurs ions containing compound in a two step process. The two-step method comprising a first mixing operation, in which a plurality of absorbent polymer structures is mixed with the fluid, and a second mixing operation, wherein the fluid within the polymer particles homogenised, wherein the polymer in the first Mischvorgang at a rate be mixed that the Bewegungsenergie of the individual polymer particles in the medium is greater than the Haftungsenergie between the individual polymer particles and the polymer particles in the second Mischvorgang be at a slower speed as mixed in the first mixing process.

The treatment of the absorbent polymer structure (Pa) with the fluid comprising the Al³⁺Ion-containing compound by the above-described two-stage process can absorbing Polymergebilde with improved Absorptionseigenschaften be obtained.

Preferably, the Al³⁺-containing Compound without consideration of crystal water in an amount in a range of 0.1 to 50 wt .-%, particularly preferably in an amount in a range of 1 to 30 wt .-%, each based on the total weight of the fluid contained in the fluid. It is further preferred that the fluid in an amount in a range of 0.01 to 15 wt .-%, particularly preferably in an amount in a range of 0.05 to 6 wt .-%, each based on the weight of absorbent Polymergebilde (Pa), with the absorbent Polymergebilden (Pa) is brought into contact.

Containing compounds preferably AI ions are A1C1₃ 6H₂O, NaA (SO₄)₂ 12 H₂O, KAI (SO₄)₂ x 12 H₂O or Al₂(SO₄)₃xl4-18 H₂O.

The present invention further relates to absorbent polymer structure (Pa), which are obtainable by the above-described inventive method.

In addition, the invention relates to an absorbent polymer structure (Pa) comprising an inner region and a surrounding the inner region outside area, wherein the Aussenbereich more highly crosslinked than the Innenbereich, in Aussenbereich, preferably only in the Aussenbereich and not in the inner region, at least one inorganic compound teilweise immobilized, and wherein the absorbent Polymergebilde (Pa) at least one of the following properties:

(SSL) at a CRC according to ERT 441.1-99 <26 g / g, an SFC of at least

7 7

80T0^" , Preferably at least 100T0^" and particularly preferably

7 1 of at least 120-10^" cm -sg^" (P2) at a CRC according to ERT 441.1-99 in the range> 26 to <27 g / g a

7 7 SFC of at least 70-10^" , Preferably of at least 90 10^" and particularly preferably at least 110-10^"7 cm³sg^_1(.beta.3) At a CRC according to ERT 441.1-99 in the range> 27 to <28 g / g, an SFC of at least 60-10^"7, Preferably at least 80- 10^"7 and particularly preferably at least 100-10^"7 cm³sg^"1(ß4) at a CRC according to ERT 441.1-99 in the range> 28 to <29 g / g a

7 7

SFC of at least 45-10^" , Preferably at least 65-10^" and

7 1 more preferably at least 85-10^" cm -sg^" (ß5) at a CRC according to ERT 441.1-99 in the range> 29 to <30 a SFC of at least 30-10^"7, Preferably at least 50T0^"7 and most preferably at least 70-10^"7 cm³ sg^"1.

(ß6) at a CRC according to ERT 441.1-99 in the range> 30 to <31 a SFC of at least 20 10^"7, Preferably at least 40- 10^"7 and most preferably at least 60-10^"7 cm³sg^_1.

(SS7) at a CRC according to ERT 441.1-99 in the range> 31 a SFC of at least 10-10^"7, Preferably at least 20- 10^"7 and most preferably at least 30- 10^"7 cm³sg^_1,

Resulting from the above properties resulting Eigenschaftskombinationen of two or more of these properties each preferred Ausführungsformen of the inventive absorbent Polymergebildes (Pa) dar. Furthermore as erfmdungsgemässe Ausführungsformen particularly preferred is an absorbent Polymergebilde (Pa), comprising the following as letters or Buchstabenkombinationen shown properties or Eigenschaftskombinationen shows schillings, ß2, .beta.3, ß4, ß5, ß6, SS7 wherein ß2, .beta.3, ß4, ß5 and ß6 particularly preferred.

It is erfindungsgemäß further preferred that the absorbent Polymergebilde (Pa) an Absorbency Against Pressure (AAP) by ERT 442.1-99 at a pressure of 50 g / cm of at least 18 g / g, more preferably at least 20 g / g, or particularly preferably of at least 22 g / g.

It is by the inventive absorbent Polymergebilde further preferred that the radius of the Aussenbereiches smaller than twice the value of the radius of Innenbereiches.

In a particularly preferred embodiment of the absorbent polymer structure (Pa) is preferably the portion seen as exterior of the polymer structure, which is characterized in that the distance of each spatial point lying in this area from the center of the particle is at least 50%, more preferably at least 75% , or at least about 90% and further even more preferably at least 95% of the radius of the particulate absorbent polymer structure.

The inorganic compound in the inventive absorbent Aussenbereich Polymergebildes (Pa) at least teilweise immobilized is, any water-insoluble inorganic compound may be, from the stable colloidal aqueous solutions can be obtained can. A particularly preferred inorganic compound is in the outer region of the absorbent polymer structure (Pa) at least partially immobilized, is a condensate of polysilicic acids.

It is also preferred that the abovementioned features of the absorbent polymer structure (Pa) also apply to the obtainable by the aforementioned method according to the invention the absorbent polymer structure (Pa).

According to one embodiment of the invention the inventive method and the inventive absorbent Polymergebilde (Pa), it is preferred that the only with a Untergrenze specified values ​​of the present invention features an upper limit own, which is about 20 times, preferably 10 times and particularly preferably about 5 own times the most preferred value of the lower limit.

The invention further relates to a composite comprising an above-defined absorbent polymer structure (Pa) and a substrate. Preferably, the polymeric structure of the invention (Pa) and the substrate are firmly connected. Substrates films of polymers such as polyethylene, polypropylene or polyamide, metals, nonwovens, fluff, tissues, wovens, natural or synthetic fibers, or other foams are preferred.

According to the invention are preferably used as composite sealing materials, cables, absorbent cores as well as diapers and hygiene articles.

The sealing materials are preferably water-absorbent films, wherein the absorbent polymer structure (Pa) is incorporated in a polymer matrix or fiber matrix as substrate. This is preferably carried out in that the absorbent polymer structure (Pa) is mixed with a polymer or the fiber matrix-forming polymer (Pm) and then connected by optionally thermal treatment. In case that be the absorbent structure is used as a fiber, it Game can be won, which spun as the substrate with another made of a different material fibers and are then joined together, for example by weaving or knitting or directly, ie without being spun with additional fibers , Typical methods for these are at H. Savano et al., International Wire & Cable Symposium Proceedings 40.333 to 338 (1991); M. Fukuma et al., International Wire & Cable Symposium Proceedings, described 36.350 to 355 (1987) and in US 4,703,132. These disclosures are incorporated herein by reference and are thus part of the disclosure.

In the embodiment in which the composite is a cable, the absorbent polymer structure (Pa) can be preferably used as particles directly under the insulation of the cable. In another embodiment of the cable the absorbent Polymergebilde (Pa) in the form of swellable tension-resistant yarns used are. According to another embodiment of the cable the absorbent polymer structure (Pa) are used as swellable film. Again, in another embodiment of the cable the absorbing

Polymergebilde (Pa) as a moisture-absorbing core in the center of the cable can be used. The substrate forms in the case of the cable all the components of the cable which no absorbent Polymergebilde (Pa) included. Hierunter fall in the cable conductors installed as electrical conductors or Lichtleiter, optical or electrical insulation materials and components of the cable, the mechanical strength of the cable ensure as braids, woven or knitted fabric made of high tensile materials such as plastics and insulation made of rubber or other materials that prevent the destruction of the exterior of the cable.

If the composite is an absorbent core, the absorbent polymer structure (Pa) is incorporated into a substrate. This substrate is preferably fiber materials. Fiber materials, which are present in the Invention may be used may include naturally occurring fibers (modified or unmodified) and synthetic fibers. Examples of suitable unmodified and modified natural fibers include cotton, Esparto grass, bagasse, kemp, flax, silk, wool, wood pulp, chemically modified wood pulp, jute, rayon, ethyl cellulose and cellulose acetate. Suitable synthetic fibers can be made of polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylate as Orion^®, Polyvinyl acetate, polyethyl, not soluble or soluble polyvinyl alcohol, polyolefins such as polyethylene (eg PULPEX^®) And polypropylenes, polyamides, such as nylon, polyesters such as DACRON^® or Kodel, polyurethanes, polystyrenes and the like. The fibers used can comprise only naturally occurring fibers, solely synthetic fibers, or any compatible combination of naturally occurring and synthetic fibers.

The fibers used in the present invention may be hydrophilic or hydrophobic, or they may consist of a combination of hydrophilic and hydrophobic fibers are made. The term "hydrophil" as used here is, describes fibers or surfaces of fibers, which by aqueous liquids (beispielsweise aqueous body fluids), which on these fibers are deposited, wettable. Hydrophilicity and wettability are typically defined in terms of contact angle and the surface tension of the liquids and solids involved. This is described in detail in a publication of the American Chemical Society entitled "Contact Angle, Wettability and Adhesion," edited by Robert F. Gould (Copyright 1964) discussed. A fiber or surface of a fiber is wetted by a liquid (i.e., it is hydrophilic) when either the contact angle between the liquid and the fiber or its surface is less than 90 ° or when the liquid tends to spread spontaneously across the distributing surface, both conditions are usually the same. Conversely, a fiber or surface of a fiber is considered to be hydrophobic if the Kontaktwinkel greater than 90 ° and the liquid does not spontaneously on the surface of the fiber spreading.

According to preferred fibers are hydrophilic fibers. Suitable hydrophilic fibers include cellulose fibers, modified cellulose fibers, rayon, polyester fibers such as Polyefhylenterephfhalat (e.g., DACRON^®), Hydrophilic nylon (HYDROFIL^®) and the same. Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as with a surfactant-treated or silica-treated thermoplastic fibers, for example based on polyolefins such as polyethylene or polypropylene or on polyacrylates, polyamides, polystyrene, polyurethanes and the like. For reasons of availability and cost, cellulose fibers, in particular pulp fibers, for use in the present invention preferably. Further preferred hydrophilic fibers for use in the present invention are chemically stiffened cellulosic fibers. The term "chemically stiffened cellulosic fibers" designates cellulose fibers that are stiffened by chemical means to increase the stiffness of the fibers under both dry and aqueous conditions. Such agents may be chemical stiffening agents which, for example covering and / or impregnate the fibers . However, it may also be those chemical stiffening agents comprising by changing the chemical structure of the fibers, for example caused by cross-linking of polymer chains, causing a stiffening polymer stiffening agents which can cover or impregnate the cellulosic fibers.,: cationic starches, the nitrogen containing Grappen (eg, amino groups) such as those available from National Starch and Chemical Corp., Bridgewater, NJ, USA, latexes, wet strength resins, such as polyamide epichlorohydrin resin (eg, Kymene^® 557H, Hercules, Inc., Wilmington, Delaware, USA), polyacrylamide resins as beispielsweise in US 3,556,932 described are commercially available polyacrylamides such as Parez ® 631 NZ American Cyanamid Co., Stanfort, CT, USA, Hamstofformaldehyde and melamine formaldehyde resins. Fibers that by Vernetzungsbindungen in individual forms stiffened were (ie the individual stiffened Fase and the methods for their preparation) are beispielsweise described in US 3,224,926, US 3,440,135, US 3,932,209 and in US 4,035,147. Preferred crosslinking agents are glutaraldehyde, glyoxal, formaldehyde, glyoxylic acid, oxydisuccinic acid and citric acid. The data obtained by crosslinking or coating, impregnation or crosslinking stiffened cellulose fibers can be twisted or crimped, preferably the fibers are twisted and additionally curled.

Apart from the abovementioned Fasermaterialien, the core also thermoplastische materials obtained. When melting travels at least a portion of this thermoplastic material, typically caused by the capillary gradient between the fibers to the intersections of the fibers. These intersections become Verbindungsstellen for thermoplastische material. If the element is cooled, then the thermoplastic material solidifies at these intersections to form joints that hold the matrix or web of fibers in each of the respective layers together. The thermoplastischen materials may be in various forms such as particles, fibers, or combinations of particulates and fibers, are present. These materials can be comprised of a plurality thermoplastischer polymers selected from polyolefins, such as polyethylene (beispielsweise PULPEX ®) and polypropylene, polyesters, copolyesters, polyvinyl acetates, Polyethylvinylacetaten, polyvinyl chlorides, polyvinylidene chlorides, polyacrylates, polyamides, copolyamides, polystyrene, polyurethanes and copolymers of vorangehenden substances, such as vinyl chloride / Ninylacetat and the like, exist. For cores as noun rat predominantly made ​​from cellulose, preferably faserförmige materials into consideration. In a further embodiment of the core it comprises, besides the substrate and the absorbent polymer structure (Pa) more powdery substances, such as odor-binding substances, such as cyclodextrins, zeolites, inorganic or organic salts and similar materials.

In one embodiment of the absorbent core the absorbent polymer structure (Pa) is in a quantity ranging from 10 to 90, preferably from 20 to 80 and particularly preferably from 40 to 70 wt.%, Based on the core incorporated. In one embodiment of the core the absorbent Polymergebilde (Pa) as particles into the core eingearbeitet. Thereby, the absorbent polymer structure (Pa) to be homogeneously distributed in the fiber materials, they can be positioned in layered fashion between the fibrous material or the concentration of the absorbent polymer structure (Pa) can have a gradient within the fibrous material. In another embodiment of the core the absorbent polymer structure (Pa) is incorporated as a fiber in the core.

Optionally, several different absorbent polymer particles, which differ, for example, in the wicking rate, the permeability of the storage capacity, the absorption against pressure, the grain distribution or even the chemical composition may be used simultaneously. These various polymer particles may mixed together in the absorbent pad eingebracht or else locally differentiated in core placed be. Such differentiated positioning can occur towards DER thickness of the core or of the length or width of the cores.

The core can be prepared by conventional, the Fachmann known methods as the Fachmann general, the term "drum-forming" beispielsweise using Formrädern, - bags and Produktformen and correspondingly adapted metering devices for the raw materials are known, can be prepared. In addition, are modern, established methods such as the so-called airlaid process (z. B. EP 850 615, US 4,640,810) with all forms of dosing, depositing the fibers and consolidation such as hydrogen (Z. B-DE 197 50 890), thermal bonding, Latexbonding (For example, EP 850 615) and Hybridbonding, the so-called wetlaid method (for example, WO 99/49905), Carding, meltblown, spunblown processes and similar processes for producing superabsorbent nonwovens (within the meaning of the definition of EDANA, Brussels) also in combinations of these methods with and untereinander conventional methods for producing the cores. Further processes are the production of laminates in the broadest sense, and of extruded and coextruded, wet- and dry- as well as additionally reinforced structures.

In another Ausführungsfoim the absorbent cores of this includes not only the substrate and incorporated into the substrate absorbent polymer structure (Pa), which together serve as a storage layer for the body fluids, a Aufiiahmeschicht which is preferably used for the rapid absorption and distribution of the liquid in the core. Here, the Aufhahmeschicht immediately above the Speicherschicht be arranged, however, it is also possible that the Aufhahmeschicht by a preferably flüssigkeitsstabile Zwischenschicht of the Speicherschicht is separated. This intermediate layer then serves primarily as a support substrate for the Aufhahmeschicht and the storage layer. Preferred materials for this interface are polyester spun fleeces or fleeces made of polypropylene, polyethylene or nylon.

In one embodiment of the invention is the core Aufhahmeschicht free of absorbent polymer. The Aufhahmeschicht can have any suitable size and need not extend the entire length or width of Speicherschicht extend. The Aufhahmeschicht can be configured for example in the form of a strip or patch. The entire Aufhahmeschicht is preferably hydrophil, but it may also have hydrophobic components. The Aufhahmeschicht, a woven material, a nonwoven material or a other suitable type of material include. Preferably, the Aufhahmeschicht based on hydrophobic Polye Hylen-Terephfhalat fibers (PET fibers), chemically stiffened cellulose fibers or of mixtures of these fibers. Other suitable materials are polypropylene, polyethylene, nylon or biological fibers. If the Aufhahmeschicht a Vliesmaterial covers, so they can through a variety of different methods can be produced. These include Nassiegen, air laying, application in the melt, forming a spunbond, carding (this includes thermal bonding, bonding with solvents or bonding to the melt spinning process). The latter processes (training as Spinnvlies and carding) are preferred when it is desired, the fibers in the Aufhahmeschicht align, as it in such processes is easier, the fibers in a single direction to align. A particularly preferred material for the Aufhahmeschicht is a PET-spunbond.

In the embodiment in which the composite is a diaper, the components of the diaper by the absorbent polymer structure (Pa) are different, the substrate of the composite. In a preferred embodiment, the diaper includes an above-described core. In this case, different from the core components of the diaper provide the substrate of the composite. In general, a composite used as a diaper comprises a water-impermeable backsheet, a water-permeable, preferably hydrophobic upper and the absorbent polymer structure (Pa) layer comprising between the backsheet and the topsheet is disposed. This the absorbent polymer structure (Pa) layer comprising preferably an above-described core. The backsheet may comprise any material known in the art, wherein polyethylene or polypropylene are preferred. The upper layer can likewise all the Fachmann suitable materials known to contain, with polyesters, polyolefins, viscose and the like are preferred that such a porous layer revealed that a sufficient fluid passage of the topsheet is ensured. In this connection to the disclosure in US 5,061,295, US Re. 26,151, US 3,592,194, US 3,489,148 and US 3,860,003 referenced. These disclosures are incorporated herein by reference and are thus part of the disclosure.

The invention further relates to a method for producing a composite, wherein a erfmdungsgemässes absorbent polymer structure and a substrate and optionally a suitable additive are brought into contact. The bringing into contact occurs preferably by wetlaid and airlaid processes, compacting, Extra Dieren or mixing.

In addition, the invention relates to a composite obtainable by the above method.

Furthermore the invention relates to chemical products, in particular foams, Formkörper, fibers, sheets, films, cables, Dichtungsmaterialien, liquid-absorbing Hygieneartikel, carriers for plant or pilzwachstumsregulierende agent or Pflanzenschutzwirkstoffen, additives for building materials, Verpackungsmaterialien or Bodenzusätze that the inventive absorbent Polymergebilde (Pa ) or the above-described substrate include.

In addition, the invention relates to the use of the inventive absorbent Polymersgebildes (Pa) or the above-described substrate in chemical products, especially in foams, shaped articles, fibers, sheets, films, cables, Dichtungsmaterialien, flüssigkeitsaufnehmenden

Hygiene articles, carriers for plant or fungus growth regulating agents or plant protection agents, additives for building materials, packaging materials or soil additives. When used as carriers for plant or fungus growth regulating agents or plant protection agents, it is preferred that the plant or fungus growth regulating agents or plant protection active substances will be issued over a period controlled by the carrier.

The invention further relates to an aqueous solution containing at least one chemical crosslinking agent and at least one inorganic compound in dispersed colloidal form, wherein the chemical crosslinking agent and the inorganic compound correspond to those chemical crosslinkers or inorganic compounds for in connection with the inventive method described above manufacture of absorbent polymer structures have been called (Pa).

The chemical crosslinking agent is in the aqueous solution according to the invention preferably in an amount of 5 to 70 parts by weight -%, particularly preferably from 20 to 60 parts by weight -% and more preferably from 30 to 50 weight -%, based on the amount of water in the aqueous solution.

The inorganic compound in the aqueous solution according to the invention preferably in an amount of 1 to 40 wt .-%, more preferably from 1, 5 to 35 wt .-% and more preferably from 2.5 to 32 wt .-%, based on the amount of water in the aqueous solution.

IE present invention also relates to a process for the preparation of this aqueous solution, wherein an aqueous solution containing at least an inorganic compound is mixed in dispersed colloidal form with at least one chemical crosslinking agent. In this novel process, the chemical crosslinking agents as such or in the form of an aqueous solution with the aqueous solution containing the inorganic compound in dispersed colloidal form are mixed. The invention also relates to an aqueous solution which is obtainable by the above method.

The invention further relates to the use of an aqueous solution containing at least one chemical crosslinking agent and at least one inorganic compound in colloidal form or the use of an aqueous solution by the above method for preparing an aqueous solution is obtainable in the treatment of Aussenbereiches an absorbent Polymergebildes (Pul) or (Pu2). The treatment is carried out in the already mentioned in connection with the inventive method of treating the Aussenbereiches an absorbent Polymergebildes (Pul) or (Pu2) manner spelled out. The absorbent Polymergebilde (Pul) or (Pu2) corresponds to that of absorbent Polymergebilde (Pul) or (Pu2), which is also in connection with the inventive method for treating the Aussenbereiches an absorbent Polymergebildes (Pul) or (Pu2) has been described.

Finally, the invention relates to the use of an aqueous solution containing at least one chemical crosslinking agent and at least one inorganic compound in colloidal form, or the use of an aqueous solution which is obtainable by the above process for producing an aqueous solution for adjusting at least one of the following properties in an absorbent polymer structure (Pul) or (Pu2): (γl) Saline flow Conductivity (SFC), (γ2) Centrifugation retention Capacity (CRC) or

(Γ3) Absorbency against Pressure (AAP).

The resulting from the above properties

Property combinations of two or more of these properties each represent preferred forms of the novel use of the novel aqueous solution. Furthermore, as according to the invention Embodiments particularly preferred is a use of the aqueous solution to adjust the following properties or

Eigenschaftskombinationen: γl, γ2, γ3, γlγ2, γlγ3, γ2γ3, γlγ2γ3.

The invention will now be explained in more detail with reference to non-limiting examples.

EXAMPLES

MAKING UNBEHANDELTEN, ABSORBENT POLYMERGEBILDE (Pul)

A powder

A monomer solution comprising 280 g acrylic acid, to 70 mol% with sodium hydroxide solution was 466.8 grams of water, 1.4 g Polyethylenglykol 300 diacrylate and 1.68 g allyloxypolyethylene by purging with nitrogen to remove dissolved oxygen and to the Starttemperatur of 4 ° C cooled. After reaching the start temperature, the initiator solution (0.1 g of 2,2'-azobis-2-amidinopropane dihydrochloride in 10 g of H₂O, 0.3 g sodium peroxydisulfate in 10 g H₂O, 0.07 g 30% ge Wasserstofφeroxidlösung in 1 g H₂O and 0.015 g ascorbic acid was added in 2 g HO). After the final temperature had reached about 100 ° C, the resulting gel was comminuted and dried at 150 ° C for 90 minutes. The dried polymer was coarsely crushed, ground and sieved to a powder having a particle size of 150 to 850 .mu.m.

The powder A has a retention capacity of 28.8 g / g.

powder B

A monomer solution comprising 280 g of acrylic acid, which was neutralized to 70 mol% with sodium hydroxide solution, 467.6 g of water, 0.98 g of polyethylene glycol 300 diacrylate, and 1, 26 g allyloxypolyethylene was flushed with nitrogen to remove dissolved oxygen and to the start temperature of 4 ° C cooled. After reaching the start temperature, the initiator solution (0.1 g of 2,2'-azobis-2-amidinopropane dihydrochloride in 10 g of H₂O, 0.3 g Natriumperoxydi- sulfate in 10 g H₂O, 0.07 g 30% ge Wasserstofφeroxidlösung in 1 g H₂O and 0.015 g ascorbic acid in 2 g H₂O) was added. After the final temperature had reached about 100 ° C, the resulting gel was comminuted and dried at 150 ° C for 90 minutes. The dried polymer was coarsely crushed, ground and sieved to a powder having a particle size of 150 to 850 .mu.m.

The powder B has a Retentionskapazität of 31.2 g / g.

powder C

A monomer solution comprising 280 g of acrylic acid, which was neutralized to 70 mol% with sodium hydroxide solution, 468.6 g of water, 0.42 g of polyethylene glycol 300 diacrylate and 0.84 g allyloxypolyethylene was flushed with nitrogen to remove dissolved oxygen and to the Starttemperatur of 4 ° C cooled. After reaching the Starttemperaτur the initiator solution (0.1 g of 2,2'-azobis-2-amidinopropane dihydrochloride in 10 g of H₂O, 0.3 g Natriumperoxydi sulfate in 10 g H₂O, 0.07 g 30% ge Wasserstofφeroxidlösung in 1 g H₂O and 0.015 g ascorbic acid in 2 g H₂O) was added. After the final temperature had reached about 100 ° C, the resulting gel was comminuted and dried at 150 ° C for 90 minutes. The dried polymer was coarsely crushed, ground and sieved to a powder having a particle size of 150 to 850 .mu.m.

The powder C has a Retentionskapazität of 37.1 g / g.

The in the examples below stated amounts, in which the individual components, as beispielsweise the postcrosslinker, the water or the silica sol, in the treatment of the Aussenbereiches unbehandelten absorbent Polymergebildes (Pul) be used, as are amounts understood in relation to the weight of the untreated absorbent polymer structure (Pul).

ElNFLUSS THE TREATMENT OF FOREIGN AREA OF UNTREATED Absorbent Polymer Structure (Pul) ON THE RETENTION, THE PERMEABILITY AND ABSORPTION UNDER PRESSURE

Example 1 :

50 g powder A is by means of a Krups Küchenmixers with a solution of 0.5 g ethylene carbonate, 0.42 g silica sol (product Levasil®^® 200 of Bayer AG, Feststoffanteil about 30 wt -%) and 1.08 g of water with vigorous stirring and then heated for 30 min. in an oven, which was heated at 180 ° C, heated.

Example 2:

50 g powder A is by means of a Krups cake mixer with a solution of 0.5 g ethylene carbonate, 0.84 g silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 0.66 g of water with vigorous stirring and then for 30 min. in an oven, which was heated at 180 ° C, heated. Example 3:

50 g powder B is means of a Krups cake mixer with a solution of 0.5 g

Ethylene carbonate, 0.42 g silica sol (product Levasil®^® 200 of Bayer AG, solids content about 30 wt .-%) and 1.08 g of water with vigorous stirring mixed and then min for 30 seconds. in an oven, which was heated at 180 ° C, heated.

Example 4:

50 g powder B is means of a Krups cake mixer with a solution of 0.5 g ethylene carbonate, 0.84 g silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 0.66 g of water with vigorous stirring and then for 30 min. in an oven at 180 ° C temperature was heated.

Example 5:

50 g powder C by means of a Krups cake mixer with a solution of 0.5 g ethylene carbonate, 0.42 g silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 1.08 g of water with vigorous stirring and then for 30 min. in an oven at 180 ° C temperature was heated.

Comparative Example 1:

50 g powder A is mixed by means of a Krups cake mixer with a solution of 0.5 g ethylene carbonate and 1.5 g of water with vigorous stirring and then for 30 min. in an oven at 180 ° C temperature was heated.

Comparative Example 2:

50 g powder B is using a Kraps-Küchenmixers with a solution of 0.5 g ethylene carbonate and 1.5 g of water with vigorous stirring and then heated for 30 min. in an oven, which was heated at 180 ° C, heated.

Comparative Example 3:

The nachvemetzte polymer structure obtained in Comparative Example 2 with 0.84 g of silica sol (product Levasil®^® 200 from Bayer AG, Feststoffanteil about 30 wt -%) and 0.16 g of water while stirring vigorously mixed. The product is then subjected to any heat treatment step.

Comparative Example 4:

The nachvemetzte polymer structure obtained in Comparative Example 2 with 0.84 g of silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 0.16 g of water with vigorous stirring and then for 60 min. in an oven at 100 ° C temperature was heated. Comparative Example 5:

50 g powder B is means of a Krups cake mixer with a solution of 0.5 g ethylene carbonate, 0.125 g Aerosil^® (Pyrogenic silica sol of Degussa AG) and 2 g of water with vigorous stirring and then heated for 30 min. in an oven, which was heated at 180 ° C, heated. To produce the suspension of Aerosil^® in water increased quantities of water were required. Yet let no easily controllable suspension obtained, since the registered Aerosil very quickly settles and a homogeneous dose to the powder B is not possible. The coated polymer tends to Klumpenbildung and is inhomogeneous.

Comparative Example 6:

50 g powder C is mixed by a Kraps cake mixer with a solution of 0.5 g ethylene carbonate and 1.5 g of water with vigorous stirring and then for 30 min. in an oven, which was heated at 180 ° C, heated.

Comparative Example 7:

50 g powder B is using a Kraps cake mixer with a solution of 0.25 g diethylene 0.25 g silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 1.25 g of water with vigorous stirring and then for 3 min. in an oven set at 120 ° C, heated. This treatment corresponds to the treatment in Example 1 of JP 1994/16822. Comparative Example 8:

50 g powder B is using a Kraps-Küchenmixers with a solution of 0.25 g 1,3-butanediol, 0.25 g silica sol (product Levasil®^® 200 of Bayer AG, solids mixing about 30 wt .-%) and 1.25 g of water with vigorous stirring and then for 3 min. in an oven set at 120 ° C, heated. This treatment corresponds to the treatment according to Example 2 in JP 1994/16822.

The properties in Examples 1 to 4 and in the Vergleichsbeispielen 1-8 obtained absorbent Polymergebilde are in the following Table 1 together.

The produced absorbent erfindungsgemäß Polymergebilde show a significant increase in the permeability (SFC) at gleichbleibender or even increased retention gegenüber products whose Aussenbereich in the absence of a silica sol was cross-linked (Example 1 to 4, Vergleichsbeispiele 1 and 2). An after-treatment of the already post-crosslinked polymer structure with Kieslsäuresol leads regardless of the subsequent thermal treatment does not produce the desired result (Comparative Example 3, 4 and 6).

The addition of Aerosil 200^® in the post-crosslinking does not result in comparable good superabsorbents characteristics (Comparative Example 5). Furthermore, increased amounts of Aerosil are no longer disperse in an acceptable amount of water 200 and are therefore no longer dispersible.

Vergleichsbeispiele 7 and 8 show that in the invention examples of Unexamined JP 1994/16822 no good performance of the polymers in terms of their permeability and retention is to achieve. Table 1 <img id="imgf000053_0001" he="190" wi="141" file="imgf000053_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="yes" /> INFLUENCE OF TREATMENT OF OUTSIDE AREA OF UNTREATED Absorbent Polymer Structure (Pul) ON THE BANK OF AGGLOMERATION Polymer Structure.

Example 6:

50 g powder B is using a Kraps-Küchenmixers with a solution of 0.5 g ethylene carbonate, 0,125 g of silica sol (product Levasil®^® 200 from Bayer AG, Feststoffanteil about 30 wt -%) and 1.38 g of water while stirring vigorously mixed. Then, a pressure is produced from the absorbent polymer structure accommodated with the aqueous solution, and it can be determined the density and the pressure exerted to Zerstörang the compact Drack.

Example 7:

50 g powder B is using a Kraps-Küchenmixers with a solution of 0.5 g ethylene carbonate, 0,125 g of silica sol (product Levasil®^® 200 of Bayer AG, solids content about 30 wt .-%) and 1.25 g of water with vigorous stirring. Then, a pressure is produced from the absorbent polymer structure accommodated with the aqueous solution, and the density thereof and the pressure exerted to destroy the pressed part determined. Comparative Example 9:

50 g powder B is mixed by a Kraps cake mixer with a solution of 0.5 g ethylene carbonate and 1.5 g of water with vigorous stirring. Then, a pressure is produced from the absorbent polymer structure accommodated with the aqueous solution, and the density thereof and the pressure exerted to Zerstörang the pressed part determined.

The properties in Examples 5 and 6 and in Vergleichsbeispiel 9 with the aqueous solution in contact accommodated absorbent Polymergebilde are in the following Table 2 together:

Table 2

<img id="imgf000055_0001" he="40" wi="121" file="imgf000055_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="no" />

The results show that the formation of stable agglomerates is significantly suppressed by the addition of silica sol. This addition ensures that the unbehandelte absorbent Polymergebilde (Pul) with increased Flüssigkeitsmengen applied can be, without that, by lumping the processability is impaired. TEST METHODS

Permeability in the swollen state (SFC Test)

The permeability in the swollen state (Saline Flow Conductivity = SFC) takes place after a in WO 95/22356 described method. In a cylinder with a sieve to be approximately 0.9 g Superabsorbermaterial eingewogen and carefully distributed on the sieve surface. The superabsorbent material is allowed for 1 hour in synthetic urine JAYCO against a Drack of 20 g / cm² sources. After detecting the swelling height of the superabsorber is allowed to pass through the swollen gel layer at constant hydrostatic pressure 0.118 M NaCl solution from a graduated reservoir. The swollen gel layer is covered during the measurement with a special screen cylinder which ensures a uniform distribution of the 0.118 M NaCl solution above the gel and constant conditions (measuring temperature 20-25 ° C) during measurement with respect to the gel bed constitution. The pressure acting on the swollen superabsorber is still 20 g / cm. Using a computer and a balance, the amount of liquid passing through the gel layer as a function of time is determined at intervals of 20 seconds within a time period of 10 minutes. The Fliessrate g / s through the swollen gel is by Regressionsanalyse with extrapolation of the gradient and determination of Mittelpunktes to time t = 0 the Fließmenge within minutes 2-10 determined. The SFC value (K) is in cm³sg^"'is calculated and specified as follows:

_ F_s(T = 0) -L_{o ^} F_s(T = 0) - L_O

K rA - AP 139506

where F_s(T = 0) is the flow rate in g / s, L₀ the thickness of the gel layer in cm, r is the density of the NaCl solution (1, 003 g / cm³)

A is the area of ​​the upper surface of the gel layer in the measuring cylinder

(28.27 cm²), .DELTA.P Is the hydrostatic Drack, which acts upon the gel

(4,920 dyne / cm²), And K is the SFC value.

DETERMINATION OF AGGLOMERATION BANK

The inclination of flüssigkeitsbeschichteten superabsorbers to form agglomerates is a Indiciser of JR Johanson Inc. determined. For this, the superabsorbent is coated with the postcrosslinker under investigation and then fed to 50 g of the powder of the investigation. The unit produces a defined pressure of 160,000 Pascal by means of a press ram in a hollow metal cylinder having an inner diameter of 5.23 cm, a compact having a height of about 2 cm. This compact is subsequently destroyed by the passage of a second cylinder having a diameter of 4.2 cm, again, to the applied force is measured.