EP2015788A2

EP2015788A2 - Production of highly-permeable, superabsorbent polymer structures

Info

Publication number: EP2015788A2
Application number: EP07724419A
Authority: EP
Inventors: Mirko Walden; Rainer Teni; Armin Reimann; Harald Schmidt
Original assignee: Stockhausen GmbH; Chemische Fabrik Stockhausen GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2006-04-21
Filing date: 2007-04-20
Publication date: 2009-01-21
Also published as: CN101113208B; US9133342B2; CN101113208A; DE102006019157A1; TW200804485A; WO2007121941A2; KR20090015068A; JP2009534483A; US20090105389A1; JP5638801B2; TWI468447B; KR101389190B1; WO2007121941A3

Abstract

The invention relates to a superabsorbent polymer composition containing: a water-absorbent polymer structure that is at least surface cross-linked and comprises a surface; a plurality of fine-grained particles that is at least partially immobilised on the surface of the structure. The invention also relates to a method for producing a superabsorbent polymer composition, to the superabsorbent polymer composition that can be obtained using said method, to a composite comprising the superabsorbent polymer composition according to the invention, to a method for producing a composite, to the composite that can be obtained using said method, to the use of the superabsorbent polymer composition according to the invention in chemical products and to chemical products comprising said superabsorbent polymer composition or composite.

Description

Production of high-permeability, superabsorbent polymer structures

The present invention relates to a superabsorbent composition, a process for producing a superabsorbent composition, the superabsorbent composition obtainable by this process, a composite comprising the superabsorbent composition according to the invention, a process for producing a composite, the composite obtainable by this process, the use of the superabsorbent composition according to the invention chemical products and chemical products comprising the superabsorbent composition or the composite according to the invention.

Superabsorbents are water-insoluble, crosslinked polymers which are capable of absorbing, and retaining under pressure, large quantities of water, aqueous liquids, in particular body fluids, preferably urine or blood, while swelling and forming hydrogels. Superabsorbents preferably absorb at least 100 times their own weight in water. Further details of superabsorbents are disclosed in "Modern Superabsorbent Polymer Technology", F.L. Buchholz, A.T. Graham, Wiley-VCH, 1998 ". By virtue of these characteristic properties, these water-absorbing polymers are mainly incorporated in sanitary articles such as, for example, baby diapers, incontinence products or sanitary napkins.

The currently commercially available superabsorbents are essentially crosslinked polyacrylic acids or crosslinked starch-acrylic acid graft polymers in which the carboxyl groups are partially neutralized with sodium hydroxide solution or potassium hydroxide solution. These are obtainable by free-radical polymerization of monomeric acrylic acid or salts thereof in the presence of suitable crosslinking agents. Different polymerization processes can be used, for example solution polymerization, emulsion polymerization or suspension polymerization. At long last For example, water absorbing polymers in particulate form having a particle diameter in a range of 150 to 850 microns are obtained by these different methods, which are then incorporated into the sanitary articles.

In particular, to improve the absorbency of the water-absorbing polymers under a compressive load, the carboxylate groups in the surface area are post-crosslinked to form a core-shell structure. For example, it is known from DE-A-4020 780 to react the water-absorbing polymers with alkylene carbonates which can react with the carboxyl groups of the polymers.

For aesthetic and environmental reasons, there is an increasing tendency to make sanitary articles such as baby diapers, incontinence products and sanitary napkins, in which the above-described water-absorbing polymers in the form of fibers or particles are usually used, ever smaller and thinner. In order to ensure a consistent total retention capacity of the sanitary articles, this requirement can only be met by reducing the proportion of large-volume fluff. As a result of this, the water-absorbing polymers have further tasks with regard to transport and distribution of liquid, which can be summarized as permeability properties.

In the case of superabsorber materials, permeability is understood to mean the ability to transport liquids added in the swollen state and distribute them in a three-dimensional manner. This process takes place in the swollen polymer gel via capillary transport through spaces between the gel particles. Liquid transport by swollen polymer 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 usage situation of the sanitary article. Although the above-described surface postcrosslinking effects an improvement in the absorption under a pressure load, because the postcrosslinking counteracts the known phenomenon of "gel blocking", in which swollen polymer particles stick together and thereby prevent further liquid absorption alone does not improve the interparticular transport of the liquid and thus the permeability.

To increase the permeability, it is known from the prior art, for example, to carry out the surface postcrosslinking in the presence of cations, in particular in the presence of aqueous aluminum salt solutions, as described, for example, in DE-A-199 09 838. DE-A-102 49 821 proposes adding an inorganic sol, for example silicic acid sol, during the surface postcrosslinking in order to improve the permeability of the water-absorbing polymers.

The disadvantage of the aftertreatment processes known from the prior art is that although they lead to an improvement in the permeability properties, they also at the same time often cause a marked deterioration of the absorption properties under pressure.

The object of the present invention was to mitigate or even overcome the disadvantages resulting from the prior art.

In particular, the present invention has the object to provide a method for producing water-absorbing polymers, which at the same time cause the lowest possible "gel-blocking" effect when incorporated into absorbent structures with a high polymer content and are also able, in the swollen state to disperse liquids that penetrate the absorbent structure as quickly and evenly as possible. The present invention was also based on the object of specifying a method by which water-absorbing polymers having the advantageous properties described above can be prepared in a simple manner.

The present invention was also based on the object of specifying a composite which as far as possible shows no "gel-blocking" effect and, moreover, is capable of distributing liquids which penetrate the composite rapidly and uniformly within the composite.

A contribution to the solution of the abovementioned objects is afforded by a superabsorbent composition comprising

an at least surface-crosslinked, water-absorbing polymer structure having a structure surface,

a plurality of ultrafine particles at least partially immobilized on the structure surface.

The surface-postcrosslinked water-absorbing polymer structure contained in the superabsorbent composition of the present invention may be a fiber, a foam or a particle, with fibers and particles being preferred, and particles being particularly preferred.

According to preferred polymer fibers are dimensioned so that they can be incorporated into or as yarn for textiles and also directly in textiles. It is preferred according to the invention that the polymer structures present as polymer fibers have a length in the range of 1 to 500 mm, preferably 2 to 500 mm and more preferably 5 to 100 mm and a diameter in a range of 1 to 200 denier, preferably 3 to 100 Denier and more preferably 5 to 60 Denier own. Polymer particles preferred according to the invention are dimensioned so that they have an average particle size according to ERT 420.2-02 in a range from 10 to 3000 μm, preferably 20 to 2000 μm and particularly preferably 150 to 850 μm or 150 to 600 μm. It is particularly preferred that the proportion of the polymer particles having a particle size in a range of 300 to 600 microns at least 30 wt .-%, more preferably at least 40 wt .-% and most preferably at least 50 wt .-%, based on the total weight of the post-crosslinked water-absorbing polymer particles is.

In a preferred embodiment of the superabsorbent composition according to the invention, this contains water-absorbing polymer structures, which

(αl) 20-99.999 wt .-%, preferably 55-98.99 wt .-% and particularly preferably 70-98.79 wt .-% of polymerized, ethylenically unsaturated, acid group-carrying monomers or their salts or polymerized, ethylenically unsaturated , a protonated or quaternized nitrogen-containing monomers, or mixtures thereof, wherein at least ethylenically unsaturated, acid group-containing monomers, preferably acrylic acid-containing mixtures are particularly preferred, (α2) 0-80 wt .-%, preferably 0-44.99 parts by weight % and more preferably 0.1-44.89% by weight of polymerized, monoethylenically unsaturated monomers copolymerizable with (α1), (α3) 0.001-5% by weight, preferably 0.01-3% by weight, and especially prefers

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

0.1-5 wt .-% of a water-soluble polymer, (α5) 0 to 20 wt .-%, preferably 2.5 to 15 wt .-% and particularly preferably

3 to 10 wt .-% water, as well

(α6) 0 to 20 wt .-%, preferably 0 to 10 wt .-% and particularly preferably 0.1 to 8 wt .-% of one or more auxiliaries, wherein the sum of the amounts by weight (αl) to (α6) is 100 wt .-%.

The monoethylenically unsaturated, acid group-carrying monomers (αl) may be partially or completely, preferably partially neutralized. The monoethylenically unsaturated monomers containing acid groups are preferably neutralized to at least 25 mol%, particularly preferably to at least 50 mol% and moreover preferably to 50-80 mol%. Reference is made in this connection to DE 195 29 348 A1, the disclosure of which is hereby incorporated by reference. The neutralization can be done partially or completely even after the polymerization. Furthermore, the neutralization can be carried out with alkali metal hydroxides, alkaline earth metal hydroxides, ammonia and also carbonates and bicarbonates. In addition, every other base is conceivable, which forms a water-soluble salt with the acid. Also a mixed neutralization with different bases is conceivable. Preference is given to neutralization with ammonia and alkali metal hydroxides, particularly preferably with sodium hydroxide and with ammonia.

Furthermore, with a polymer, the free acid groups may predominate, so that this polymer has a pH lying in the acidic range. This acidic water-absorbing polymer may be at least partially neutralized by a polymer having free basic groups, preferably amine groups, which is basic as compared to the acidic polymer. These polymers are referred to in the literature as mixed-bed ion-exchange absorbent polymers (MBIEA polymers) and are disclosed, inter alia, in WO 99/34843 A1 The disclosure of WO 99/34843 A1 is hereby incorporated by reference, and Thus, MBIEA polymers are typically a composition that is capable of exchanging anions for basic polymers that are capable of reacting with anions and, on the other hand, a polymer that is acidic in comparison to the basic polymer The basic polymer has basic groups and is typically obtained by the polymerization of monomers bearing basic groups or groups which can be converted into basic groups. These are, above all, those which have primary, secondary or tertiary amines or the corresponding phosphines or at least two of the above functional groups. In particular, ethyleneamine, allylamine, diallylamine, 4-aminobutene, alkoxycycline, vinylformamide, 5-aminopentene, carbodiimide, formaldacin, melamine and the like, as well as their secondary or tertiary amine derivatives, belong to this group of monomers.

Preferred ethylenically unsaturated, acid group-carrying monomers (αl) are preferably those compounds which are described in WO 2004/037903 A2, which is hereby incorporated by reference and therefore as part of the disclosure, as ethylenically unsaturated, acid group-carrying monomers (αl) to be named. Particularly preferred ethylenically unsaturated, acid group-carrying monomers (αl) are acrylic acid and methacrylic acid, with acrylic acid being most preferred.

According to one embodiment of the present invention, water-absorbing polymer structures are used in which the monoethylenically unsaturated monomers (α2) copolymerizable with (α1) are acrylamides, methacrylamides or vinylamides.

Preferred (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-dimethylamino (meth) acrylamide, dimethyl (meth) acrylamide or diethyl (meth) acrylamide. Possible vinylamides are, for example, N-vinylamides, N-vinylformamides, N-vinylacetamides, N-vinyl-N-methylacetamides, N-vinyl-N-methylformamides, vinylpyrrolidone. Particularly preferred among these monomers is acrylamide.

According to another embodiment of the present invention, water-absorbing polymer structures are used in which the monoethylenically unsaturated monomers (α2) which are copolymerizable with (α1) are water-soluble monomers. are mere. In this connection, alkoxypolyalkylene oxide (meth) acrylates such as methoxypolyethylene glycol (meth) acrylates are particularly preferred.

Furthermore, water-dispersible monomers are preferred as monoethylenically unsaturated monomers (α2) which are copolymerizable with (α1). As the water-dispersible monomers, preferred are acrylic acid esters and methacrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate or butyl (meth) acrylate.

The monoethylenically unsaturated monomers (α2) copolymerizable with (α1) further include methyl polyethylene glycol allyl ether, vinyl acetate, styrene and isobutylene.

Crosslinkers (α3) used are preferably those compounds which are mentioned in WO 2004/037903 A2 as crosslinking agents (α3). Among these crosslinkers, water-soluble crosslinkers are particularly preferred. Most preferred are N, N'-methylenebisacrylamide, polyethylene glycol di (meth) acrylates, triallylmethylammonium chloride, tetraallylammonium chloride and allylnonaethylene glycol acrylate prepared with 9 moles of ethylene oxide per mole of acrylic acid.

As water-soluble polymers (α4), water-soluble polymers such as partially or completely saponified polyvinyl alcohol, polyvinylpyrrolidone, starch or starch derivatives, polyglycols or polyacrylic acid can be present in the polymer structures, preferably in copolymerized form. The molecular weight of these polymers is not critical as long as they are water-soluble. Preferred water-soluble polymers are starch or starch derivatives or polyvinyl alcohol. The water-soluble polymers, preferably synthetic, such as polyvinyl alcohol, can also serve as a grafting base for the monomers to be polymerized. As auxiliaries (α6), preference is given to adjusting agents, odor binders, surface-active agents or antioxidants and also those additives which were used to prepare the polymer structures (initiators, etc.) in the polymer structures.

In a particular embodiment of the superabsorbent composition according to the invention, this contains water-absorbing polymer structures which are based on at least 50% by weight, preferably at least 70% by weight and moreover preferably at least 90% by weight, on carboxylate-carrying monomers. It is further preferred according to the invention that component (α1) consists of at least 50% by weight, preferably at least 70% by weight, of acrylic acid, which is preferably at least 20 mol%, particularly preferably at least 50 mol%. % and more preferably is neutralized in a range of 60 to 85 mol%.

Furthermore, the water-absorbing polymer structures contained in the superabsorbent composition according to the invention are surface-modified, at least surface-postcrosslinked. Due to the surface postcrosslinking, the outer region of the polymer structures has a higher degree of crosslinking than the inner region, so that a core-shell structure is formed.

As water-absorbing polymer structures, the superabsorbent composition according to the invention preferably contains those polymers which have been obtained by a process comprising the process steps:

a) free-radical polymerization of acid group-bearing, ethylenically unsaturated, optionally partially neutralized monomers in the presence of a crosslinking agent to form a gel-like polymer structure;

b) optionally comminuting the gelatinous polymer structure; c) drying the optionally comminuted gel-form polymer structure to obtain water-absorbing polymer structures;

d) optionally grinding the absorbent polymer sheet thus obtained and screening to a desired particle size fraction;

e) post-crosslinking of the surface of the structure of the resulting water-absorbing polymer structures, wherein the process step e) before or after the process step c), preferably after the process step d) is carried out.

The radical polymerization taking place in process step a) is preferably carried out in aqueous solution, this aqueous solution preferably being used in addition to water as solvent

(αl) the ethylenically unsaturated, acid group-carrying monomers or their salts, acrylic acid being particularly preferred as the acid group-carrying monomer,

(α2) optionally monoethylenically unsaturated monomers copolymerizable with (α1),

(α3) the crosslinker,

(α4) optionally a water-soluble polymer, and (α6) optionally one or more auxiliaries

includes.

As ethylenically unsaturated, acid group-carrying monomers (αl), as monoethylenically unsaturated, with (αl) copolymerizable monomers (α2), as crosslinker (α3), as water-soluble polymers (α4) and as auxiliaries (α6) are in turn those compounds preferably already mentioned in the context of the novel polymer structures as ethylenically unsaturated, Acid group-carrying monomers (αl), as monoethylenically unsaturated, with (αl) copolymerizable monomers (α2), as crosslinking agents (α3), as water-soluble polymers (α4) and as auxiliaries (α6) were called.

From the abovementioned monomers, comonomers, crosslinkers, water-soluble polymers and auxiliaries, the water-absorbing polymer structures can be prepared by various polymerization methods. For example, in this context, bulk polymerization, which is preferably carried out in kneading reactors such as extruders, solution polymerization, spray polymerization, inverse emulsion polymerization and inverse suspension polymerization may be mentioned.

Preferably, the solution polymerization is carried out in water as a solvent. The solution polymerization can be carried out continuously by polymerization on a belt conveying the reaction mixture, as disclosed in DE 35 44 770 A1, or discontinuously. From the prior art, a wide range of possible variations in terms of reaction conditions such as temperatures, type and amount of initiators and the reaction solution can be found. Typical methods are described in the following patents: US 4,286,082, DE 27 06 135, US 4,076,663, DE 35 03 458, DE 35 44 770, DE 40 20 780, DE 42 44 548, DE 43 23 001, DE 43 33 056, DE 44 18 818. The disclosures are hereby incorporated by reference and thus are considered part of the disclosure.

The polymerization is initiated as usual by an initiator. As initiators for the initiation of the polymerization, it is possible to use all initiators which form free radicals under the polymerization conditions and which are customarily used in the production of superabsorbers. It is also possible to initiate the polymerization by the action of electron beams on the polymerizable, aqueous mixture. However, in the absence of initiators of the abovementioned type, the polymerization can also be initiated by the action of high-energy radiation in the presence of photoinitiators. the. Polymerization initiators can be dissolved or dispersed in a solution of monomers according to the invention. Suitable initiators are all compounds which decompose into free radicals which are known to the person skilled in the art. These include in particular those initiators which are already mentioned in WO 2004/037903 A2 as possible initiators.

With particular preference, a redox system consisting of hydrogen peroxide, sodium peroxodisulfate and ascorbic acid is used to prepare the water-absorbing polymer structures.

The inverse suspension and emulsion polymerization can also be used to prepare the polymer structures. According to these processes, an aqueous, partially neutralized solution of the monomers (αl), and (α2), optionally including water-soluble polymers (α4) and auxiliaries (α6), dispersed by means of protective colloids and / or emulsifiers in a hydrophobic organic solvent and by Radical initiators started the polymerization. The crosslinkers are either dissolved in the monomer solution and are metered together with this or added separately and optionally during the polymerization. If appropriate, the addition of a water-soluble polymer (α4) as a grafting base is carried out via the monomer solution or by direct introduction into the oil phase. Subsequently, the water is removed azeotropically from the mixture and the polymer is filtered off.

Furthermore, both in the solution polymerization and in the inverse suspension and emulsion polymerization, the crosslinking can be effected by copolymerization of the polyfunctional crosslinker dissolved in the monomer solution and / or by reaction of suitable crosslinkers with functional groups of the polymer during the polymerization steps. The methods are described, for example, in publications US 4,340,706, DE 37 13 601, DE 28 40 010 and WO 96/05234 A1, the corresponding disclosure of which is hereby incorporated by reference. The gelatinous polymer structures obtained in the solution polymerization or the inverse suspension and emulsion polymerization in process step a) are dried in process step c).

In particular, in the case of solution polymerization, it is preferred that the gelatinous polymer structures are first comminuted before drying in an additional process step b). This comminution is carried out by comminution devices known to those skilled in the art, such as a chopper (see DE 195 18 645 C1) or a mincer, for example, which can be connected downstream of the chopper.

The drying of the gel-shaped polymer structure is preferably carried out in suitable dryers or ovens. By way of example rotary kilns, fluidized bed dryers, plate dryers, paddle dryers or infrared dryers may be mentioned. Furthermore, it is preferred according to the invention that the drying of the hydrogel in process step c) takes place to a water content of 0.5 to 25 wt .-%, preferably from 1 to 10 wt .-%, wherein the drying temperatures usually in a range of 100 to 200 ° C lie.

The dried water-absorbing polymer structures obtained in process step c), in particular if they were obtained by solution polymerization, can still be ground in a further process step d) and sieved to the desired grain size mentioned at the outset. The grinding of the dried, water-absorbing polymer structures is preferably carried out in suitable mechanical comminution devices, such as a ball mill.

The gelatinous polymer structure obtained in process step a), the comminuted gelatinous polymer structure obtained in process step b), the dried polymer structure obtained in process step c) or the Step d) obtained, ground, dried polymer structures, preferably the milled, dried polymer structure obtained in process step d) is modified in a further process step e) in the region of the structure surface, preferably at least postcrosslinked. In this case, the structure surface of the gel-like or dried polymer structure, but of the ground, dried polymer structure, is brought into contact with a preferably organic, chemical surface postcrosslinker. The postcrosslinker, in particular when it is not liquid under the postcrosslinking conditions, is brought into contact with the structure surface of the polymer structures via a solvent. The solvents used are preferably water, water-miscible organic solvents, such as methanol, ethanol, 1-propanol, 2-propanol or 1-butanol, or mixtures of at least two of these solvents, with water being the most preferred solvent. It is further preferred that the postcrosslinker be present in the solvent or mixture in an amount in a range of from 5 to 75% by weight, more preferably from 10 to 50% by weight and most preferably from 15 to 40% by weight, based on the total weight of the solvent or solvent mixture.

The contacting of the structure surface of the polymer structure with the solvent or the solvent mixture comprising the postcrosslinker preferably takes place in the process according to the invention by good mixing of the solvent or solvent mixture with the polymer structure.

Suitable mixing units for mixing are z. As the Patterson-Kelley mixer, DRAIS turbulence mixers, Lödigemischer, Ruberg mixers, screw mixers, plate mixers and fluidized bed mixers and continuously operating vertical mixers in which the polymer structure is mixed by means of rotating blades in rapid frequency (Schugi mixer).

In the process according to the invention, the polymer structure is preferably used in the postcrosslinking with at most 20% by weight, particularly preferably with very high at least 15% by weight, moreover preferably with at most 10% by weight, moreover still more preferably with at most 5% by weight of solvent, preferably water, brought into contact.

In the case of polymer structures in the form of preferably approximately spherical particles, it is further preferred according to the invention for the contacting to be such that only the structure surface, but not the inner region of the particulate polymer structures, comes into contact with the solvent or the solvent mixture and thus with the postcrosslinker is brought.

As postcrosslinkers with which the polymer structures can be postcrosslinked, compounds which have at least two functional groups which can react with functional groups of a polymer structure in a condensation reaction (= condensation crosslinker), in an addition reaction or in a ring opening reaction are preferably used. Preferred postcrosslinkers in the process according to the invention are those which have been mentioned in WO 2004/037903 A2 as crosslinkers of crosslinking classes II.

Among these compounds, particularly preferred crosslinking agents are condensation crosslinkers such as, for example, diethylene glycol, triethylene glycol, polyethylene glycol, glycerol, polyglycerol, propylene glycol, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, trimethylolpropane, pentae - Rythritol, polyvinyl alcohol, sorbitol, l, 3-dioxolan-2-one (ethylene carbonate), 4-methyl-1, 3-dioxolan-2-one (propylene carbonate), 4,5-dimethyl-1, 3 -dioxolan-2 -on, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3 Dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, and more preferably 1,3-dioxolan-2-one. After the polymer structures comprising the postcrosslinker were brought into contact with the post-crosslinking agent or with the fluid, they are heated to a temperature in a range of 50 to 300 ⁰ C, preferably 75 to 275 ° C and more preferably 150 to 250 ° C heated so that preferably the structure surface is more strongly crosslinked compared to the inner region of the polymer structures (= post-crosslinking). The duration of the heat treatment is limited by the risk that the desired property profile of the polymer structures is destroyed as a result of the action of heat.

The ultrafine particles at least partially immobilized on the structure surface may be an organic or inorganic fines, with an inorganic fines being particularly preferred.

Furthermore, according to a particular embodiment of the superabsorbent composition according to the invention, the very fine particles are water-soluble fines, whereby water-soluble fines are preferably fines, of which at 25 ° C. at least 1 g, preferably at least 5 g and most preferably at least 10 g 100 ml of water can be dissolved.

According to another particular embodiment of the superabsorbent composition according to the invention, the ultrafine particles are water-insoluble fines, with water-insoluble fines preferably being fines, of which less than 1 g, preferably less than 0.1 g and most, at 25 ° C. preferably less than 0.01 g can be dissolved in 100 ml of water.

Furthermore, it is preferred according to the invention for the preferably inorganic fines to have an at least bivalent, preferably at least trivalent, metal. Preferred, at least divalent metals are selected from the group comprising beryllium, magnesium, calcium, barium, strontium, aluminum, boron, zirconium, silicon, scnadium, vanadium, cerium, yttrium, lanthanum, niobium, chromium, molybdenum, manganese, palladium, platinum, cadmium, mercury, iron, Copper, zinc, titanium, cobalt or nickel, with aluminum being the most preferred.

Furthermore, it is preferred according to the invention for the preferably inorganic fines to be present as a salt comprising the at least divalent metal in the form of an at least divalent cation K ^{n +} (with n> 2) and at least one anion A ^{m "} (with m> 1).

Very fine particles which are particularly preferred according to the invention are selected from the group consisting of aluminum salts, such as aluminum chloride, polyaluminum chloride, aluminum sulfate, aluminum nitrate, bis-aluminum-potassium sulfate, bis-aluminum-sodium sulfate, aluminum lactate, aluminum oxalate, aluminum citrate, aluminum glyoxylate, Aluminum succinate, aluminum itaconate, aluminum crotonate, aluminum butyrate, aluminum sorbate, aluminum malonate, aluminum benzoate, aluminum tartrate, aluminum pyruvate, aluminum valerate, aluminum formate, aluminum glutarate, aluminum propanate or aluminum acetate, phosphates of the formula M ₄ P ₂ O ₇ , M ₂ HPO ₄ or M ₃ PO ₄ wherein M is one equivalent of a metal selected from calcium, magnesium, strontium, barium, zinc, iron, aluminum, titanium, zirconium, hafnium, tin, cerium, scandium, yttrium or lanthanum or mixtures thereof, such as calcium hydrogen phosphate , tertiary calcium phosphate, apatite, Thomas flour of the formula Ca ₅ (PO ₄ ) [SiO ₄ ], Berini t of the formula AlPO ₄ or Rhenaniaphosphat of formula 3 CaNaPO ₄ Ca ₂ SiO ₄ , calcium chloride, calcium nitrate, magnesium chloride, magnesium sulfate, magnesium nitrate, zinc chloride, zinc sulfate, zinc nitrate, copper sulfate, cobalt chloride, zirconium chloride, zirconium sulfate, zirconium nitrate; Silicas, especially fumed silica, such as is for example available under the tradename Aerosil ^® or precipitated silicas, as they are commercially available under the name Sipernat ^®, titanium dioxides, zinc oxide, aluminum hydroxide, Aluminum acetylacetonate, zirconium acetylacetonate, tin oxide, mixed oxides between zinc, aluminum, titanium, zirconium, tin and / or silicon, such as aluminium titanate, aluminum titanium oxide, zinc titanium oxide

Most preferred fine particles are aluminum salts selected from the group consisting of AlCl ₃ .6H ₂ O, NaAl (S0 ₄₎ ₂ x 12 _H2O, KAl (S0 ₄₎ ₂ x 12 H ₂ O, A1 ₂ (SO ₄₎ ₃ x 14-18 H ₂ O, aluminum lactate or aluminum citrate, with A1 ₂ (SO ₄ ) ₃ × 14-18 H ₂ O moreover being particularly preferred. As a further preferred compound, which is regarded as an aluminum salt, Al (O) OH is mentioned.

According to a particular embodiment of the composition according to the invention, this composition comprises at least two different fines, for example an aluminum salt and a salt other than an aluminum salt, or else two different aluminum salts.

Furthermore, it is preferred according to the invention that at least 50% by weight, particularly preferably at least 75% by weight, more preferably at least 95% by weight and most preferably at least 99% by weight, of the ultrafine particles have an average particle diameter ( Weight average) in a range of 10 to 1,000 .mu.m, preferably from 50 .mu.m to 800 .mu.m, particularly preferably from 100 to 600 .mu.m and most preferably from 200 to 400 .mu.m, in each case determined by methods known in the art for particle size determination, preferably by sieve analysis or by means of a coulter counter.

According to a particular embodiment of the superabsorbent composition according to the invention, the proportion of very fine particles having a mean particle size> 150 μm is more than 20% by weight, particularly preferably more than 30% by weight and moreover more preferably more than 40% by weight, in each case on the total weight of Feinstteilchen. According to a particular embodiment of the superabsorbent composition according to the invention, the fines are immobilized on the structure surface via a binder.

In this context it is particularly preferred that the binder as a binder main component is water and / or an organic compound includes, wherein the organic compound at 2O ⁰ C is preferably a solid.

It is particularly preferred that the organic compound is a preferably linear polymer, preferably a linear polymer selected from the group comprising polyurethanes, polyesters, polyamides, polyesteramides, polyolefins, polyvinyl esters, polyethers, polystyrenes, polyimides, in particular polyetherimides, polyimines, sulfur polymers, in particular Polysulfone, polyacetals, in particular polyoxymethylenes, fluoroplastics, in particular polyvinylidene fluoride, styrene olefin copolymers, polyacrylates, ethylene-vinyl acetate copolymers or mixtures of two or more of said polymers, among these polymers polycondensates and among these polyethers being particularly preferred and linear polyethers are most preferred.

Particularly suitable linear polyethers include polyalkylene glycols, in particular polyethylene glycols, polypropylene glycols, poly (ethylene / propylene) glycols with random or blocky arrangement of the ethylene or propylene monomers or mixtures of at least two of these polyalkylene glycols.

Further suitable, preferably linear polymers are those polymers which are referred to as "thermoplastic adhesives" in DE-A-103 34 286. The disclosure content of DE-A-103 34 286 with regard to thermoplastic adhesives is hereby introduced as a reference and forms part of it the disclosure of the present invention. Further, it is preferable in the invention that the organic compound as the binder main component has a weight average molecular weight M _w in a range of 100 to 1,000,000 g / mol, more preferably in a range of 1,000 to 100,000 g / mol, and most preferably in a range from 5,000 to 20,000 g / mol.

According to a particular embodiment of the superabsorbent composition according to the invention, at least two, more preferably at least 50% by weight, more preferably at least 75% by weight, more preferably at least 95% by weight and most preferably at least 99% by weight. %, each based on the total weight of the Feinstteilchen, the plurality of fine particles together to form a Feinstteilchenagglomerat, wherein a Feinstteilchenagglomerat consists of at least two finely agglomerated with each other Feinstteilchen. In this case, on the one hand, the very fine particles are at least partially connected to one another via the binder with the obtainment of very fine particle agglomerates and, on the other hand, the very fine particles or very fine particle agglomerates are connected to the structure surface via the binder.

Furthermore, it is preferred according to the invention that at least 25% by weight, preferably at least 50% by weight and most preferably at least 75% by weight, of the surface of the water-absorbing polymer structures in the superabsorbent composition of the invention are free of binders.

It is also preferred according to the invention that the amount of fines in a range of 0.001 to 10 wt .-%, more preferably in a range of 0.01 to 5 wt .-%, and most preferably in a range of 0.1 to 2 wt .-%, each based on the weight of the water-absorbing polymer structures, while the weight of the binder is preferably in a range of 0.0001 to 5 wt .-% and particularly preferably in a range of 0.001 to 2 wt .-% , in each case based on the weight of the water-absorbing polymer structures. The weight ratio between fines and binder is preferably in a range of fines: binder of from 20: 1 to 1:20, more preferably from 10: 1 to 1:10, and most preferably from 10: 1 to 2: 1.

The superabsorbent composition according to the invention is furthermore preferably characterized by at least one of the following properties: (β1) an AAP value of at least 15 g / g, preferably at least 20 g / g, determined according to ERT 442.2-02 at a pressure of 0.3 psi most preferably at least 25 g / g;

(β2) an AAP value determined according to ERT 442.2-02 at a pressure of 0.7 psi of at least 12 g / g, preferably at least 15 g / g and most preferably at least 20 g / g; a according to the test method described herein (SS3) specific SFC value of at least HO x 10 ^"7 cm ³ sec / g, more preferably of at least 130 x ^{10" 7} cm certain ³ sec / g at a CRC according to ERT 441.2-02 Value from> 20 g / g to <22 g / g;

a according to the test method described herein (SS4) specific SFC value of at least 90 x 10 ^"7 cm ³ sec / g, more preferably at least

110 x 10 ^"7 cm ³ sec / g at a in accordance with ERT 441.2-02 CRC value determined of> 22 g / g to <24 g / g;

(β5) an SFC value determined according to the test method described herein of at least 7O x 10 ^" cm s / g, more preferably of at least 90 x 10 ^{" 7} cm ³ s / g with a CRC value determined according to ERT 441.2-02 of > 24 g / g to <26 g / g;

a according to the test method described herein (SS6) specific SFC value of at least 50 x 10 ^"7 cm ³ sec / g, more preferably of at least 70 x ^{10" 7} cm certain ³ sec / g at a CRC according to ERT 441.2-02 Value from> 26 g / g to <28 g / g; (SS7) a particular according to the test method described herein SFC value of at least 30 * 10 ^"7 cm ³ sec / g, more preferably of at least 50 s x ^{10 -7} cm ³ / g determined in accordance with ERT 441.2-02, a CRC value of> 28 g / g to <30 g / g; (SS8) a according to the test method described herein certain SFC value of at least 1O x IO ^"7 cm ³ sec / g, more preferably of at least 30 x ^{10" 7} cm ³ s / g with a CRC value of> 30 g / g determined according to ERT 441.2-02.

Further preferred embodiments of the superabsorbent composition according to the invention have every conceivable combination of the above features (β1) to (β8), the embodiments of the following combinations of features being preferred: (β1), (β2), (β3), (β4), (β5) , (ß6), (ß7),

(β1 Xβ2) (β3) (β4) (β5) (β6) (β7) (β8) is the most preferred combination of properties.

A contribution to the solution of the abovementioned objects is also made by a process for the production of a superabsorber composition, including as process steps

i) providing an at least surface-crosslinked, water-absorbing polymer structure having a structure surface;

ii) providing a fines particle component comprising a plurality of fines;

iii) mixing the fines component comprising a plurality of fines with the water-absorbent polymer structure; iv) immobilizing at least a portion of the fines on the formation surface.

The water-absorbing, surface-postcrosslinked polymer structure provided in process step i) is preferably those polymer structures which have already been described above in connection with the superabsorber composition according to the invention. According to a particular embodiment of the process according to the invention, a polymer structure obtained in step d) of the above-described process for producing water-absorbing polymer structures is provided as water-absorbing, surface-postcrosslinked polymer structure in process step i), this polymer structure being brought into contact with a postcrosslinker solution, but has not yet been heated to the post-crosslinking temperature required for post-crosslinking. In this case, the process step comprises the provision of a (not yet) surface-postcrosslinked water-absorbing polymer structure.

As ultrafine particles which are contained in the very fine particle component provided in process step ii), preference is likewise given to those very fine particles which have already been mentioned at the outset in connection with the superabsorbent composition according to the invention. The amount of fines used is preferably in a range of 0.001 to 10 wt%, more preferably in a range of 0.01 to 5 wt%, and most preferably in a range of 0.1 to 2 wt%, in each case based on the weight of the water-absorbing polymer structures.

According to a particularly preferred embodiment of the process according to the invention, the ultrafine particle component additionally comprises a binder, preference being given to those binders which have already been mentioned in connection with the superabsorbent composition according to the invention as binders. Particularly preferred among these binders are particulate re binder, in particular particulate polyalkylene glycols, such as particulate polyethylene glycols or polypropylene glycols, it being particularly preferred that the particulate binder to at least 50 wt .-%, particularly preferably at least 75 wt .-%, moreover to more preferably at least 95% by weight and most preferably at least 99% by weight of particles having a mean particle diameter (weight average) of less than 500 μm, preferably less than 400 μm, more preferably less than 300 μm and most preferably less than 150 .mu.m, in each case determined by methods known in the art for particle size determination, preferably by sieve analysis or by means of a Coulter counter.

Accordingly, in addition to the provision of the water-absorbing polymer structures in process step i), the process according to the invention also comprises the provision of a very fine particle component in process step ii) by mixing a particulate binder with the ultrafine particle, preferably by mixing a particulate polyalkylene glycol with a particulate aluminum salt. The weight ratio between the fines and the particulate binder is preferably in the range of fines: binder of from 20: 1 to 1:20, more preferably from 10: 1 to 1:10, and most preferably from 10: 1 to 2: 1.

The mixing of the ultrafine particles with the particulate binder to obtain the Feinstteilchenkomponente can be carried out by all known in the art mixing devices, with suitable mixing units z. B. a Patterson-Kelley mixer, a DRAIS turbulence mixer, a Lödigemischer, a Ruberg mixer, a screw mixer, a plate mixer, a fluidized bed mixer and continuously operating vertical mixer, in which the polymer structure is mixed by means of rotating blades in fast frequency (Schugi mixer). In process step iii), the ultrafine particle component provided in process step ii) is mixed with the surface-postcrosslinked, water-absorbing polymer structures provided in process step i), in which case the above-mentioned mixing devices can once again be used.

After or during mixing in process step iii), in process step iv) at least a portion of the ultrafine particles is immobilized on the structure surface, the immobilization preferably taking place by heating. It is particularly preferred that the immobilization is carried out by heating to a temperature which is at most 10%, more preferably at most 7.5% and most preferably at most 5% above the softening temperature of a constituent of the Feinstteilchenkomponente, preferably above the softening temperature of the binder, he follows. More preferably, the heating is to a temperature in a range of 30 to 200 ° C, more preferably of 50 to 160 ° C, further more preferably from 50 to 16O ⁰ C and most preferably from 100 to 140 ⁰ C. If, in process step i), a water-absorbing polymer structure has been provided which has already been brought into contact with a postcrosslinker solution but has not yet been heated to the postcrosslinking temperature required for postcrosslinking, it may be advantageous if a higher Temperature, for example, a temperature in a range of 100 to 25O ⁰ C, particularly preferably from 120 to 200 ⁰ C, is maintained.

Basically, at least four approaches are conceivable:

According to variant VA, the mixture of ultrafine particle component and water-absorbing polymer structure is first prepared in process step iii) and then heated to the above-mentioned temperature for the purpose of immobilizing the ultrafine particles, the water-absorbing polymer structure already being surface-postcrosslinked can or wherein the water-absorbing polymer structure has been brought into contact with the postcrosslinked, but has not yet been heated to a temperature required for a surface postcrosslinking.

According to variant V _B , the water-absorbing polymer structures are first heated to the above-described temperature before process step iii), and then, in process step iii), these preheated water-absorbing polymer structures are mixed with the non-preheated ultrafine particle component.

According to variant Vc, the water-absorbing polymer structure and the Feinstteilchenkomponente are heated separately to the temperature described above before step iii) and then mixed in step iii) the preheated water-absorbing polymer structures with the also preheated Feinstteilchenkomponente. According to a particular embodiment of this variant Vc, it is preferable first to cool the ultrafine particle component after heating and before mixing with the preheated water-absorbent polymer structures, preferably to a temperature in a range from 10 to 100 ° C., particularly preferably from 15 to 75 ° C and most preferably 20 to 60 ⁰ C, then optionally comminuted, for example by means of a mortar, and then to mix the cooled and optionally comminuted Feinstteilchenkomponente with the preheated water-absorbing polymer structures.

According to variant V _D , the fines particle component is first heated to the above-described temperature before process step iii), and then, in process step iii), the preheated fines particle component is mixed with the non-preheated water-absorbing polymer structures. According to a particular embodiment, variant V ₀ , it is preferred to first cool the Feinstteilchenkomponente after heating and before mixing with the non-preheated water-absorbing polymer structures, preferably to a temperature in a range of 10 to 100 ° C, more preferably 15 to 75 ° C and on Most preferably 20 to 60 ⁰ C, then optionally comminute, for example by means of a mortar, and then to mix the cooled and optionally comminuted Feinstteilchenkomponente with the non-preheated water-absorbing polymer structures.

The term "non-preheated" means preferably that the temperature of the respective component is less than 100 ° C, more preferably less than 80 ° C, and most preferably less than 40 ° C.

The duration of heating, depending on the mixing speed and the mixing device used, is preferably in a range of 10 seconds to 60 minutes, more preferably in a range of 30 seconds to 30 minutes.

Furthermore, it may be advantageous if the method step iv) is followed by a further method step v), in which the superabsorbent composition is mixed for a period of time in the range from 10 minutes to 5 hours, more preferably from 30 minutes to 3 hours, in order to allow the most homogeneous possible distribution of the ultrafine particles or of the ultrafine particle agglomerates and the absorbent polymer structures, for which purpose mixing devices known to the person skilled in the art can be used. In this further process step, the superabsorbent composition can be introduced into the mixer with the temperature which it has after immobilization in process step iv), the superabsorbent composition then preferably being cooled steadily to a lower temperature, preferably to room temperature, in the course of the mixing , A contribution to achieving the abovementioned objects is also made by a superabsorbent composition obtainable by the process described above. These superabsorbent composition is preferably characterized by the omposition described in connection with the initially described inventive superabsorbent _Z absorptive properties, in particular by the given there AAP-values, SFC values and CRC values.

According to an inventive embodiment of the superabsorbent composition according to the invention and of the method according to the invention, it is preferred that the values of features according to the invention indicated only with a lower limit have an upper limit which is 20-fold, preferably 10-fold and particularly preferably 5-fold of the most preferred value of the lower limit.

A further contribution to the solution of the objects described at the outset is provided by a composite comprising the superabsorbent composition according to the invention or the superabsorbent composition obtainable by the process according to the invention and a substrate. It is preferred that the superabsorbent composition and the substrate are firmly bonded together. As a substrate, films of polymers such as polyethylene, polypropylene or polyamide, metals, nonwovens, fluff, tissues, fabrics, natural or synthetic fibers or other foams are preferred. Furthermore, it is preferred according to the invention that the composite comprises at least one region which contains the superabsorbent composition according to the invention in an amount in the range of about 15 to 100% by weight, preferably about 30 to 100% by weight, particularly preferably about 50 to 99 , 99 wt .-%, further preferably from about 60 to 99.99 wt .-% and more preferably from about 70 to 99 wt .-%, each based on the total weight of the relevant region of the composite includes, said range preferably has a size of at least 0.01 cm ³ , preferably at least 0.1 cm ³ and most preferably at least 0.5 cm ³ . A particularly preferred embodiment of the composite according to the invention is a sheet-like composite, as described in WO-A-02/056 812 as "absorbent material." The disclosure of WO-A-02/056812, in particular with regard to the exact Structure of the composite, the basis weight of its components and its thickness is hereby incorporated by reference and forms part of the disclosure of the present invention.

A further contribution to achieving the abovementioned objects is provided by a process for producing a composite, in which the superabsorbent composition according to the invention or the superabsorbent composition obtainable by the process according to the invention and a substrate and optionally an additive are brought into contact with one another. The substrates used are preferably those substrates which have already been mentioned above in connection with the composite according to the invention.

According to a particular embodiment of the method according to the invention for producing a composite, this method comprises the following method steps:

I) providing a substrate;

II) providing an at least surface-crosslinked, water-absorbing polymer structure having a structure surface;

III) providing a fines particle component comprising a plurality of fines;

rV) bringing into contact the substrate with the at least surface-crosslinked, water-absorbing polymer structure; V) contacting the at least surface-crosslinked, water-absorbing polymer structure with the Feinstteilchenkomponente;

VI) Immobilizing at least a portion of the Feinstteilchen on the structure surface.

As the ultrafine particle component, the fines particle component which has already been described above in connection with the process according to the invention for producing a superabsorbent composition as the preferred fines particle component is preferred.

According to a variant of this particular embodiment of the method according to the invention for producing a composite, the substrate and the surface-postcrosslinked polymer structure are first brought into contact with one another, preferably by initially introducing the substrate and then applying the surface-postcrosslinked polymer structure either uniformly or to specific areas of the substrate surface. is preferably scattered. Subsequently, the water-absorbing polymer structures located on the substrate surface are then brought into contact with the very fine particle component, for example by scattering the very fine particle component onto the surface-postcrosslinked polymer structures located on the substrate surfaces. Finally, the immobilization of the Feinstteilchenkomponente takes place on the structure surface, wherein this immobilization is preferably carried out by the above described in connection with the inventive method for producing the superabsorbent composition heating. In this variant of the particular embodiment of the method according to the invention for producing a composite, the method step V) is therefore carried out after the method step FV).

According to another variant of this particular embodiment of the method according to the invention for producing a composite, the substrate is first of all submitted. Subsequently, the surface-postcrosslinked polymer structure is brought into contact with the substrate, preferably by initially introducing the substrate and then applying the surface-postcrosslinked polymer structure either uniformly or else to specific areas of the substrate surface, preferably by scattering. Even before the polymer structure is brought into contact with the substrate surface, the water-absorbing polymer structures are brought into contact with the very fine particle component, for example by mixing the very fine particle component with the surface post-crosslinked polymer structure before it is scattered onto the substrate surface. After the polymer structures have been brought into contact with the substrate, then the immobilization of the Feinstteilchenkomponente on the structure surface then succeed. In this variant of the particular embodiment of the method according to the invention for producing a composite, therefore, the method step V) takes place before the method step IV).

A contribution to achieving the abovementioned objects is also provided by a composite obtainable by the process described above, this composite preferably having the same properties as the composite according to the invention described above.

A further contribution to the solution of the abovementioned objects is provided by chemical products comprising the superabsorbent composition according to the invention or a composite according to the invention. Preferred chemical products are, in particular, foams, moldings, fibers, films, cables, sealing materials, hygiene-containing hygiene articles, in particular diapers and sanitary napkins, carriers for plant- or fungi-growth-regulating agents or crop protection active ingredients, additives for building materials, packaging materials or floor additives.

Also, the use of the superabsorbent composition or the inventive composite in chemical products, preferably in the abovementioned chemical products, in particular in hygiene articles such as diapers or sanitary napkins, and the use of the superabsorbent particles as carriers for plant or fungi growth-regulating agents or crop protection active ingredients contribute to the solution of the abovementioned objects. When used as a carrier for plant or fungi growth regulating agents or crop protection actives, it is preferred that the plant or fungi growth regulating agents or crop protection actives can be delivered for a period of time controlled by the carrier.

The invention will now be explained in more detail by means of test methods and non-limiting examples.

test methods

Determination of the SFC value

The determination of the permeability in the swollen state (Saline Flow Conductivity = SFC) is carried out according to a method described in WO-A-95/22356. In a cylinder with a sieve bottom approx. 0.9 g of superabsorbent material (the entire particle fraction) is weighed in and carefully distributed on the sieve surface. The superabsorbent material is allowed to swell in JAYCO synthetic urine for 1 hour against a pressure of 20 g / cm ² . After detecting the swelling height of the superabsorber, at a constant hydrostatic pressure, 0.118 M NaCl solution is run from a leveled storage vessel through the swollen gel layer. 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 (measurement temperature 20-25 ⁰ C) during the measurement with respect to the gel bed nature. The pressure acting on the swollen superabsorber is still 20 g / cm ² . With the help of a computer and a balance, the amount of liquid layer as a function of time, recorded at intervals of 20 seconds within a time period of 10 minutes. The flow rate g / s through the swollen gel layer is determined by regression analysis with extrapolation of the slope and determination of the center point to the time t = 0 of the flow rate within minutes 2-10. The SFC value (K) was given in cm.sup.- ¹ and calculated as follows:

F _s (t = 0) - L _ϋ _ F _s (t = 0) - L _o

K = r - A AP, 139506

where F _s (t = O) is the flow rate in g / s,

L ₀ the thickness of the gel layer in cm, r the density of the NaCl solution (1, 003 g / cm ³ ),

A is the area of the top of the gel layer in the measuring cylinder

(28.27 cm ² ), ΔP is the hydrostatic pressure that rests on the gel layer

(4,920 dyne / cm ² ), and K is the SFC value.

Examples

1. Preparation of a surface-postcrosslinked polymer structure

A monomer solution consisting of 300.0 g of acrylic acid, 233.11 g of NaOH (50%), 442.75 g of deionized water, 1.18 g of monoallylpolyethylene glycol 750 monoacrylic acid ester and 0.577 g of polyethylene glycol 300 diacrylate is removed by purging with nitrogen freed of dissolved oxygen and cooled to the starting temperature of 4 ° C. After reaching the starting temperature, the initiator solution (0.3 g of sodium peroxydisulfate in 10.0 g of H ₂ O, 0.07 g of 35% hydrogen peroxide solution in 10.0 g of H ₂ O and 0.015 g Ascorbic acid in 2.0 g H ₂ O). After the final temperature of about 86 ⁰ C was reached, the resulting gel was crushed and dried at 150 ⁰ C for 120 minutes. The dried polymer was coarsely crushed, ground to a particle size of less than 2,000 μm in a SM 100 granulator and sieved to a powder having a particle size of 150 to 850 μm.

100 g of the polymer particles obtained in this way were mixed with a total of 4 g of an aqueous solution consisting of 1 g of ethylene carbonate and 3 g of water in a laboratory mixer and then heated in an oven for a period of 30 minutes at 180 ° C.

The AAP value at a pressure of 0.7 psi, the CRC value and the SFC value of this water-absorbing polymer structure were determined (see the results in Table 1).

2. Immobilization of Feinstteilchen

100 g of the polymer obtained in Production Example 1 was preheated to 130 ° C. in a drying cabinet.

A mixture of 10 g Al ₂ (Sθ ₄₎ ₃ ^χ l4 H ₂ O, which was milled in a centrifugal mill to a particle large and in a range of 300 to 400 microns sieved, and 1.5 g of polyethylene glycol 10,000 (polyethylene glycol with a molecular weight of 10,000 g / mol), which was also ground in a centrifugal mill and screened to a particle size of less than 300 microns) was prepared. 1.15 g of the mixture of Al ₂ (SO ₄ ) 3 × 1 ₄ H ₂ O and polyethylene glycol 10,000 were mixed in a Krup's mixer with stirring with the preheated water-absorbing polymer structure. The AAP value at a pressure of 0.7 psi, the CRC value and the SFC value of this superabsorbent composition according to the invention were also determined (see the results in Table 1).

Table 1

Claims

claims

1. A superabsorbent composition including

an at least surface-crosslinked water-absorbing polymer structure having a structure surface,

2. The composition of claim 1, wherein the fines are immobilized via a binder.

3. A composition according to claim 1 or 2, wherein at least two of the plurality of the fine particles are combined together to form a Feinstteilchenagglomerat.

A composition according to any one of claims 2 to 4, wherein the binder includes as an essential binder component an organic compound.

5. The composition of claim 4, wherein the organic compound at 2O ⁰ C is a solid,

A composition according to claim 4 or 5, wherein the organic compound is a polymer.

7. The composition according to any one of claims 4 to 6, wherein the organic

Compound is a linear polymer.

A composition according to any one of claims 4 to 7, wherein the organic compound is a linear polyether.

The composition according to any one of claims 4 to 8, wherein the organic compound has a weight average molecular weight M _w in a range of 100 to 1,000,000 g / mol.

A composition according to any one of claims 4 to 9, wherein the organic compound is a polyalkylene glycol.

A composition according to any one of claims 4 to 10, wherein the organic compound is a polyethylene or polypropylene glycol.

12. A composition according to any one of the preceding claims, wherein at least 50% by weight of the fines have an average particle diameter in a range of from 10 to 1000 μm.

13. The composition according to any one of the preceding claims, wherein the Feinstteilchen are inorganic.

14. The composition according to any one of the preceding claims, wherein the Feinstteilchen have an at least divalent metal cation.

15. A composition according to any one of the preceding claims wherein the fines comprise aluminum.

16. The composition according to any one of the preceding claims, wherein the Feinstteilchen present as a salt.

17. A composition according to any one of the preceding claims wherein the fines include at least two different fines.

18. A process for producing a superabsorbent composition comprising as process steps

ii) providing a fines particle component comprising a plurality of fines;

iii) mixing the fines component comprising a plurality of fines with the water-absorbent polymer structure;

iv) immobilizing at least a portion of the fines on the formation surface.

The method of claim 18, wherein the fines component additionally includes a binder.

20. The method of claim 19, wherein the fines particulate component is premixed with the binder prior to mixing with the water-absorbent polymer structure.

21. The method according to any one of claims 18 to 20, wherein the immobilization is carried out by heating.

22. The method according to any one of claims 18 to 21, wherein the immobilization is carried out by heating to a maximum of 10% above the softening temperature of a component of Feinstteilchenkomponente.

23. A composition obtainable by a process according to any one of claims 18 to 22.

24. A composition according to any one of claims 1 to 17 or 23, wherein the composition is characterized by at least one of the following properties:

(ßl) one determined according to ERT 442.2-02 at a pressure of 0.3 psi

AAP value of at least 15 g / g;

(β1) an AAP value of at least 12 g / g determined according to ERT 442.2-02 at a pressure of 0.7 psi;

(β3) an SFC- determined according to the test method described herein

Value of at least HOx 10 ^"7 cm ³ s / g at a temperature in accordance with ERT 441.2

02 determined CRC value of> 20 g / g to <22 g / g;

(SS4) a according to the test method described herein certain SFC value of at least 9Ox ^{10 -7} cm ³ sec / g at a in accordance with ERT 441.2-02 CRC value determined by> 22 g / g to <24 g / g;

a according to the test method described herein (SS5) specific SFC value of at least 70 ^χ 10 ^"7 cm ³ sec / g at a in accordance with ERT 441.2-02 CRC value determined of> 24 g / g to <26 g / g ( ß6) an SFC-type determined according to the test method described herein.

Value of at least 50x 10 ^"7 cm ³ sec / g at a in accordance with ERT 441.2-02 CRC value determined of> 26 g / g to <28 g / g;

(SS7) a according to the test method described herein certain SFC value of at least 30 ^χ ^{10 -7} cm ³ sec / g at a in accordance with ERT 441.2-02 CRC value determined by> 28 g / g to <30 g / g; (SS8) a according to the test method described herein certain SFC value of at least 10x 10 ^"7 cm ³ sec / g at a ERT 441.2-02 determined in accordance with CRC-value of> 30 g / g.

25. A composite comprising a superabsorbent composition according to any one of claims 1 to 17 or 23 and a substrate.

26. A process for producing a composite comprising a superabsorbent composition according to any one of claims 1 to 17 or 23 and a substrate, wherein the polymer structures and the substrate are brought into contact with each other.

27. The method according to claim 26, comprising the following method steps:

I) providing the substrate;

III) providing one containing a plurality of fines

fine particulate;

IV) contacting the substrate with the at least surface-crosslinked, water-absorbing polymer structure;

V) contacting the at least surface-crosslinked, water-absorbing polymer structure with the ultrafine particle component;

VI) immobilizing at least a portion of the fines on the structure surface.

28. The method of claim 27, wherein the method step V) after the Process step IV) takes place.

29. The method according to claim 27, wherein the method step V) takes place before the method step IV).

30. composite, obtainable by a method according to one of claims 26 to 29.

31. Chemical products, comprising a superabsorbent composition according to one of claims 1 to 17 or 23 or a composite according to claim 25 or 30.

32. Use of a superabsorbent composition according to any one of claims 1 to 17 or 23 or a composite according to claim 25 or 30 in chemical products.