Blood- and/or body fluid-absorbing hydrogel

Translation of description of equivalent WO 2005042039 A2

Blood and / or body fluids absorbent hydrogel

description

The present invention relates to blood and / or body fluids absorbent hydrogels, a process for the preparation of the blood and / or body fluid absorbent hydrogels and their use.

Further embodiments of the present invention are the claims to refer to the description and the examples. It is understood that the features mentioned above and not only in the particular combination indicated but also in other combinations are still to be explained features of the subject invention can be used without departing from the scope of Erindung.

Swellable hydrogel-forming polymers, known as superabsorbent (super Absorbing polymer, SAP), are known from the prior art.

Swellable hydrogel-forming polymers are in particular polymers of (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable grafting base, crosslinked cellulose loose-or starch ethers, crosslinked carboxymethylcellulose, partially crosslinked polyalkylene oxide or in aqueous fluids swellable natural products, for example guar derivatives. Such hydrogels are used as aqueous solutions absorbing products to produce diapers, tampons, sanitary napkins and other hygiene articles, but also as water-retaining agents in market gardening or to thicken all types of waste, in particular, uses of medical waste.

Swellable hydrogel-forming polymers are preferably capable strength with an absorption of 0.9 wt .-% saline solution of at least 10 times their own weight based on the polymer, and preferably 20 times their own weight. This absorption is preferably achieved even under a pressure of 0.7 psi for example.

To improve their performance characteristics swellable hydrogel-forming polymers are typically surface or gelnachvemetzt.

This postcrosslinking is known to those skilled in the art and is preferably in the aqueous gel phase or as surface of the ground and off seventh polymer particles.

Waste, particularly medical waste and any type of waste, which are loaded with toxic, infectious or dangerous for humans and the environment substances, must be handled and transported safely. A superabsorbent can immobilize by taking the liquid waste most dangerous substances.

Medical waste, especially hospital waste from operating rooms, consist mainly of blood, body fluids and saline that is used as a rinse.

Conventional superabsorbents are then optimized in hygiene articles, especially baby diapers to absorb urine. They always show a much lower absorption of blood compared with synthetic urine or physiological saline. the absorption of blood and saline differs significantly, so different amounts superabsorbent must be added depending on the composition of the waste. This would mean in practice that superabsorbents needs to be either generally added far overdosed, or that optionally superabsorbent has to be fed. It actually closed containers would however be opened again several times, if appropriate, which requires additional time and represents a risk for people who have to deal with the waste.

It is therefore highly advantageous to provide a superabsorbent which is capable of absorbing larger amounts of blood than commercially available superabsorbents. For hospital waste and medical waste can be solidified so solutions with varying amounts of blood equally well.

Another aspect in the treatment of medical wastes with superabsorbents is the absorption rate. In commercial superabsorbents, especially for baby diapers and incontinence products, a very high absorption rate is not advantageous because the liquid to be absorbed is distributed first through the absorbent article. A superabsorbent having very high swelling rate does not allow the uniform distribution of the liquid in the hygiene article but absorb the entire liquid immediately. In contrast to conventional diapers is critical in medical waste and feminine hygiene products such as tampons, napkins and deposits, the rapid absorption of blood and / or body fluids. The high absorption rate is important to look at the medical waste to absorb as quickly as possible and immobilize it.

The rapid solidification allows faster and safer handling of such waste, for example during transport and storage.

A further advantageous behavior for the absorption of medical wastes is, when a portion of the added superabsorbent after the addition to the solution floats on the liquid surface, drops and a further part. This is the produces a rapid thickening, since the superabsorbent can swell from two interfaces of, on the other hand, the surface of the liquid is immediately covered with superabsorbent and leakage of substances, such as viruses or bacteria more difficult, in particular splashing of liquid is avoided.

For feminine hygiene products, a rapid absorption is desirable to quickly transport the fluid away from the body and store in the hygiene article. Besides its rapid absorption and high swelling rate and a high retention is necessary.

For hygiene products the higher blood absorption is a major advantage because the development of very effective and thin hygiene articles is possible, which are preferred by the customer because of the wearing comfort.

The patent application WO-A-99/55767 describes the use of aluminates for surface post of uncrosslinked or covalently crosslinked hydrogels. The application teaches that under pressure is improved by the subsequent crosslinking of the gel strength, absorption of liquids and blood, in particular the absorption. The swell and the swimming behavior of the post-crosslinked hydrogel is however unsatisfactory.

The patent application DE-A-199 09 653 teaches the application of an aqueous solution of a cation before or after a postcrosslinking. Regardless of whether this treatment is carried out before or after the post-crosslinking reaction, the required characteristics can not be achieved by this treatment.

The patent application WO-A-00/10496 describes an optimized material for absorbing blood by application of kaolinite to moistened superabsorbent and subsequent drying. The application does not teach the combination of different coatings and is not sufficient to obtain superabsorbents having the desired properties.

The patent application WO-A-95/17455 describes a porous superabsorbent which can also swim in the swollen state in water. This is generated by dispersed th nitrogen in the superabsorbent and can not be realized by an aftertreatment. It is also an application point of no benefit if the superabsorbent completely floating on the liquid.

The patent application EP-A-0 759460 describes a material which was postcrosslinked again by addition of large amounts of Oberflächennachvemetzungsreagenzes. The higher crosslinking does not lead to products with very high blood absorption. The patent application WO-A-95/19191 describes the production of superabsorbent materials with improved blood absorption. Commercially available superabsorbents are additionally sprayed with polyols, such as polyethylene glycol or glycerol. The additional crosslinking of the polymer strands is carried out mainly by hydrogen bonds. The superabsorbent available according to the teachings of this application are due to lack of buoyancy not to cover liquid surfaces.

The patent applications WO-A-98/42193, CA-A-2, 188.838, WO 95/15771 and JP-A 03/044367 describes the use of superabsorbents with biocides, such as polyvinylpyrrolidone / iodine complexes and glutaraldehyde , Commercially available superabsorbents are mixed with a biocide. This does not lead to an improvement of the blood absorption, nor to an increase in Absorptionsgeschwin- speed, but only to a disinfection of the thickened solution.

The patent application JP-A-06/345980 describes the mixture of superabsorbents with anionic surfactants. This improves neither the blood absorption, nor does it increase the rate of absorption.

It was therefore the object to develop a special superabsorbent which is ideally suited for solidifying medical waste. This superabsorbent must by rapid absorption and thickening or hardening allow safe handling of medical waste.

Another problem to be solved is to provide a superabsorbent available, the same time shows a significantly increased blood absorption and a rapid swell. Such superabsorbent would be not only for thickening waste of all kinds, particularly medical waste suitable, but could also be very good for the absorption of fluids in feminine hygiene products such as tampons, pads and liners are used.

Another problem to be solved is to provide a superabsorbent available, the at least partially on the Flüssigkeitsoberflä- before floats after addition to the solution while another part falls. This results in rapid thickening of liquid waste is firstly effected, since the superabsorbent can swell from two interfaces of, on the other hand, the surface of the liquid is immediately covered with superabsorbent and leakage of substances, such beispielseise viruses, bacilli or bacteria difficult.

Surprisingly, it has now been found that the inventive treatment of known superabsorbent materials with hydrophobic and optionally hydrophilic compounds a higher swelling rate and improved blood absorption is achieved. Preferably, particulate hydrophobic and, optionally, hydrophilic compounds may be used. For after treatment with hydrophobic compounds, in particular, fumed silicas or hydrophobic mixtures of pyrogenic silicas and pyrogenic aluminas suitable. For after treatment with hydrophilic compounds, in particular pyrogenic silicas or mixtures of pyrogenic silicas and pyrogenic aluminas suitable.

When used within the process of the invention super absorbierenen materials are hydrogels or Hydrogelgemische. The water content of the hydrogels is preferably less than 20 wt .-%, particularly preferably less than 10 wt .-%, most preferably less than 1 wt .-%.

The terms "hydrophobic" and "hydrophilic" describe the wetting behavior of a surface with water. On hydrophobic surfaces of the edge or contact angle of a water drop is <90 ° and on hydrophilic surfaces is the boundary or contact angle of a water drop> 90 °. The edge or contact angle is, for example, in Colloid Polym. Sci., Vol 259 (1981), pages 391-394, described.

For example, located on the particle surface fumed silicas free hydroxyl groups. About this hydroxyl hydrogen bonds are possible. Characterized fumed silicas are hydrophilic.

By reacting fumed silicas with, for example, trimethylchlorosilane, the free hydroxyl groups may be converted into silyl. can form lethergruppen The silylating no hydrogen bonds more. The fumed silica was hydrophobized.

The amounts of hydrophilic and hydrophobic particles are advantageously selected so that both an increased rate of swell, as well as a partial floating of the superabsorbent particles is achieved on the liquid surface at the beginning of the swelling process. The additional coating with hydrophobic particle tikein part of the superabsorbent remains after addition of all the necessary superabsorbent amount to be thickened liquid at the surface of the material to be thickened. Another part of the treated superabsorbent sinks slowly in the thickening solution to as superabsorbents based on poly-acrylates usually have a higher density than that to be thickened solutions. Without treatment, a commercially available superabsorbent would simply fall only directly by adding to the solution. The amount of hydrophobic particles can be individually set, wherein the proportion of post-treated superabsorbent floating on the liquid to be thickened, with increasing content rises hydrophobic particles. If the superabsorbent for example treated with hydrophilic substances, so is the amount of hydrophobic particles to increase where appropriate.

By initially partially remaining on the surface amount of superabsorbent superabsorbent starts now both from the bottom of the vessel upwards, as well as from the surface down to the swell to be thickened solution. This results in the same time several technical advantages:

Firstly, to be thickened solution is solidified faster as a superabsorbent which swells from both sides, has to cover only half the source route.

- Secondly, the surface of the solution to be thickened is almost immediately covered with superabsorbent. The superabsorbent then acts like a cork on the vessel and allow safe transport and safe disposal of waste, since the leakage of liquid, contaminated ingredients more during transport of the container.

The combination of hydrophilic and hydrophobic particles superabsorbents can be produced with high swelling rate, which at least partially float at the beginning of the swelling process in water and aqueous surfaces and can strengthen the content of a vessel with medical waste quickly.

The invention is a process for the aftertreatment of absorbent hydrogels comprising the steps of:

Treatment with at least one hydrophobic compound, preferably hydrophobic and / or hydrophobicized clay minerals, hydrophobized aluminum oxides and / or hydrophobicized silicas, aluminas particularly preferably hydrophobic and / or hydrophobicized silicas as for example Aerosil R 812, Aerosil R 974 or Aerosil® R 8200 ( Degussa Aktiengesellschaft, Germany). optionally treatment with at least one hydrophilic compound, preferably hydrophilic clays, aluminas and / or silicas, more preferably aluminas and / or silicas, such as Aerosil® 200 (Degussa Aktiengesellschaft, Germany).

Preferably, the hydrophobic and hydrophilic compounds are used as particles. The average particle size is usually from 0.001 to 10 .mu.m, preference , 0.002 to 5 .mu.m, more preferably 0.005 to 1 micron, and most preferably 0.01 to 0.1 .mu.m. The measurement method for the particle size distribution based on the analysis of diffraction spectra by Fraunhofer. Analyses are standard with a Mastersizer S, a laser instrument from Malvern, performed. Particularly preferred are fumed aluminas, fumed silicas or mixtures thereof. Very particular preference is given to mixtures of fumed silicas with greater than 0 to 20 wt .-% fumed alumina, and fumed silicas. The average primary particle size is preferably 5 to 50 nm, particularly preferably 10 to 20 nm, and the specific surface area is preferably 10 to 1000 m²/ G, particularly preferably 80 to 380 m²/G. are typically used 0.005 to 20 wt .-%, preferably 0.05 to 10 wt .-%, particularly preferably 0.1 to 5 wt .-%, most preferably below 1 wt .-%, hydrophobic, hydrophobic or hydrophilic compound based on the absorbent hydrogel.

Hydrophobic aluminas and / or silicas can be obtained for example by reacting hydrophilic aluminas and / or silicas with hexamethyldisilazane or dimethyldichlorosilane.

The hydrophobic and hydrophilic compounds are preferably mixed with the dried water-absorbing hydrogel. Dry preferably means a water content of less than 20 wt .-%, particularly preferably of less than 10 wt .-%. The manner of mixing is not limited, preferably using reaction mixers or mixing and drying systems such as Lodige.RTM mixer BEPEX® mixer NAUTA® mixer SCHUGGI® mixer, NA RA® dryers and PROCESSALL® , Moreover, fluidized bed dryers can be used. The mixture is advantageously carried out using a residence time of 1 to 180 minutes, preferably from 2 to 20 minutes, particularly preferably from 5 to 20 minutes, and a rotational speed of 10 to 1000 U / min, preferably from 50 to 300 U / min, particularly preferably from 50 to 250 U / min is performed.

Another object of the invention is a process for the aftertreatment of absorbing hydrogels comprising the steps of:

Treatment with at least one polyvalent metal ions, solutions of polyvalent metal ions, water-soluble cationic polymers and / or solutions of water-soluble polymers, preferably multivalent metal ions, such as Al³⁺, Fe²⁺, Fe³\ Ti³⁺, Ti⁴⁺, Co²⁺, Ni²⁺, Cr³⁺, Mn²⁺, Zn²⁺, Mg²⁺, Ca²⁺, ZP Zr⁴⁺, Particularly preferably Al³⁺,

- Treatment with at least one hydrophobic compound, preferably hydrophobic and / or hydrophobicized clay minerals, hydrophobized aluminum oxides and / or hydrophobicized silicas, particularly preferably hydrophobic Bierte aluminas and / or hydrophobicized silicas, such as Aerosil® R812, Aerosil® R974 or Aerosil® R 8200 (Degussa Aktiengesellschaft, Germany).

- Where appropriate, treatment with at least one hydrophilic compound, preferably hydrophilic clays, aluminas and / or silicas, more preferably aluminas and / or silicas, such as Aerosil® 200 (Degussa Aktiengesellschaft, Germany).

- Optionally post-treatment with at least one anionic, cationic and / or nonionic surfactant, preferably a non-ionic tenside, such as, for example, sorbitan esters having an HLB value of from 2 to 18, Span® is more preferably 80 (Uniqema, NL).

The counter ions of polyvalent metal ions is no restriction in using a solvent counter ions are preferred to ensure sufficient solubility, is preferably sulfate. Preferably, the metal ions are dosed as a solution. A particularly preferred solvent is water. The concentration of the polyvalent metal ion in the aqueous solution is typically from 1 to 20 wt .-%, preferably 2 to 10 wt .-%.

are used typically from 0.05 to 4 wt .-%, preferably 0.1 to 2 wt .-%, particularly preferably 0.2 to 1 wt .-%, of the polyvalent metal ion based on the absorbierede hydrogel.

Preferably, the surfactants are metered as a solution. A particularly preferred solvent is diethylene. The concentration of surfactant in the solution is typically from 5 to 70 wt .-%, preferably 10 to 50 wt .-%, particularly preferably 20 to 30 wt .-%.

are used typically from 0.01 to 4 wt .-%, preferably 0.05 to 2% by weight, particularly preferably 0.1 to 1 wt .-%, of the surfactant based on the absorbent hydrogel.

The order in which the post-treatment agent to be dosed is not limited, preferably the order of polyvalent metal ions, solutions of polyvalent metal ions, water-soluble cationic polymers and / or solutions of water soluble polymers, hydrophilic and hydrophobic compounds is jointly or separately, in any order surface-active compounds, such as surfactants, as well as their solutions,

preferably only polyvalent metal ions and hydrophobic compounds are used for treatment.

The dissolved after-treatment agents are preferably sprayed onto the dried water-absorbing hydrogel and mixed. The manner of mixing is subject to any restrictions, preferably using reaction mixers or mixing and drying systems such as Lodige.RTM mixer BEPEX® mixer NAUTA® mixer SCHUGGI® mixer NARA® dryer and PROCESSALL® , Moreover, fluidized bed dryers can be used. The mixture is, suitably with a residence time of 1 to 180 minutes, preferably from 2 to 15 minutes, and a rotational speed of 10 to 1000 U / min, preferably from 50 to 300 U / min, particularly preferably from 50 to 250 U / min performed.

After the last step can be dried. Drying may take place in the mixer itself, by heating the jacket or blowing in warm air. Also suitable are a downstream dryer such as a tray dryer, a rotary tube oven or a heatable screw. But it can also, for example, an azeotropic distillation as a drying process.

Preferred drying temperatures in the inventive process are in the range 50 to 250 ° C, preferably at 50 to 200 ° C, particularly preferably at 50 to 150 ° C. The residence time at this temperature in the reaction mixer or dryer is preferably below 30 minutes and preferably less than 10 minutes.

The drying is preferably conducted at reduced pressure, preferably at less than 500 mbar, particularly preferably less than 200 mbar is carried out and, where appropriate, by a dry gas stream, preferably nitrogen, in an amount of 20 to 1000 l / kgh, preferably 100 to 250 l / kgh, supported.

Preferably, the absorbent hydrogels in the process of the invention will drive additionally treated with a hydrophilic organic compound. The hydrophilic organic compounds improve the fixing of the particulate aftertreatment agent on the superabsorbent. Suitable hydrophilic organic compounds include for example, lower water-soluble polyols having an average molecular weight of 100 to 6000 g / mol, preferably 200 to 3000 g / mol, particularly preferably from 250 to 1000 g / mol. Preferred hydrophilic organic compounds are dendritic polymers, highly branched polymers such as polyglycerols, polyethylene glycols, polypropylene glycols, Statistical or block copolymers of ethylene oxide and propylene oxide. Other suitable compounds for this purpose are the polyethoxylates or polyethylene lypropoxylate of polyhydroxy compounds such as glycerol, sorbitol, trimethylolpropane, trimethylolethane, pentaerythritol. Examples are n-fold ethxoxyliert.es trimethylolpropane or glycerin wherein n represents an integer from 1 to 100. Further examples are block copolymers such as a total of n times m times and then ethoxyliert.es propoxyliert.es trimethylolpropane or glycerol where n represents an integer between 1 and 40 and m represents an integer between 1 and 40th The order of the blocks can also be reversed.

The hydrophilic organic compound may be added before, during or added by each of the treatment steps, preferably before the treatment with the hydrophobic organic compound, particularly preferably together with the polyvalent metal ion.

The hydrophilic organic compound is liquid at 23 ° C and has at 23 ° C a viscosity of less than 3000 mPas, preferably less than 1500 mPas, preferably less than 1000 mPas, particularly preferably less than 500 mPas and most preferably less than 300 mPas , on.

The hydrophilic organic compound is typically present in an amount of 0.01 to 2 wt .-%, vorugsweise from 0.1 to 1 wt .-%, particularly preferably 0.35 to 0.75 wt .-%, based on dried hydrogel used.

Another object of the invention are cross-linked water-absorbing polymers which are obtainable for example by the novel process, in particular absorbing hydrogels having a blood absorbence of at least 10 g / g, preferably of at least 15 g / g, more preferably of at least 19 g / g , very particularly preferably of at least 22 g / g and particularly preferably of at least 25 g / g, a solidification time of less than 120 seconds, preferably less than 100 seconds, more preferably less than 90 seconds, most preferably less than 80 seconds and especially preferably of less than 70 seconds and / or a floating behavior in which from 10 to 95%, preferably from 40 to 90%, particularly preferably from 65 to 80%, the solution containing to be thickened blood and / or body fluids, starting from the liquid surface is thickened, as well as their use for absorbing blood and / or body fluids, especially in hygiene articles, or for bridges thickening of aqueous solutions and / or suspensions, in particular for thickening medical waste. Another object of the invention are hygiene products which contain the inventive superabsorbents.

Usable in the process according to the invention swellable hydrogel-forming polymers are in particular polymers of crosslinked (co) polymerized hydrophilic monomers, polyaspartic acid, graft (co) polymers of one or more hydrophilic monomers on a suitable grafting base, crosslinked starch ethers or swellable in aqueous fluids natural products, for example guar derivatives. It is preferable that in the polymer to be crosslinked is a polymer containing structural units derived from acrylic acid or esters thereof or obtained by graft copolymerization of acrylic acid or acrylic esters onto a water-soluble polymer matrix. These hydrogels are known to the skilled person and for example, in US-4,286,082, DE-C-27 06 135, US-A- 4,340,706, DE-C-37 13 601, DE-C-2840010, DE-A-344 548, DE-A - ^ 020 780, DE-A ^ 0 15 085, DE-A-39 17 846, DE-A-38 07289, DE-A-35 33 337, DE-A 35 03 458, DE-A-244 548, DE -A- 2 19607, DE-A-021 847, DE-A-38 31 261, DE-A-35 11 086. DE-A-31 18 172, DE-A-3028043, DE-A ^ 4 18881 , EP-A-0801483, EP-A-0455985, EP-A-0 467 073, EP-A-0312952, EP-A-0205874, EP-A-0 499 774, DE-A 26 12 846, DE-A-4020780, EP-A-0 205 674, US-A-5,145,906, EP-A-0 530 438, EP-A-0670073, US-A ^ 1,057,521, US-A-4,062,817, US -A-, 525.527, US-A-, 295.987, US-A-5,011,892, US-A-A076.663 or US-A-4,931, 497 described.

To prepare these swellable hydrogel-forming polymers suitable hydrophilic monomers include polymerizable acids such as acrylic acid, methacrylic acid, vinylsulfonic acid, vinylphosphonic acid, maleic acid including its anhydride, fumaric acid, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanephosphonic acid and their amides, hydroxyalkyl esters and amino- or ammonio-containing esters and amides and also the alkali metal and / or ammonium salts of the monomers containing acid groups. Also suitable are water-soluble N-vinylamides such as N-vinylformamide or else diallyldimethylammonium chloride. Preferred hydrophilic monomers are compounds of the general formula I

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wherein

R¹ Hydrogen, methyl, ethyl or carboxyl, R² -COOR⁴, Hydroxysulfonyl or phosphonyl, one with a C -, - C₄-alkanol Ve- resterte phosphonyl group or a group of formula II

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R³ Hydrogen, methyl or ethyl,

R⁴ Are hydrogen, C₄Aminoalkyl, C₁-C₄Hydroxyalkyl, alkali metal or ammonium ion and

R⁵ a sulfonyl group, a phosphonyl group or a carboxyl group or a respective alkali metal or ammonium salt of.

Examples of dC₄-alkanols Are methanol, ethanol, n-propanol, isopropanol or n-butanol.

Particularly preferred hydrophilic monomers are acrylic and methacrylic acid, and alkali metal or ammonium salts, for example sodium acrylate, potassium or ammonium macrylat.

Suitable grafting bases for hydrophilic hydrogels, the unsaturated acids or their alkali metal or ammonium salts are obtainable by olefinically Pfropfcopolymerisati- on may be natural or synthetic origin. Examples are starch, cellulose or cellulose derivatives and also other polysaccharides and oligosaccharides, polyalkylene oxides, especially polyethylene oxides and polypropylene oxides, and also hydrophilic polyesters.

Suitable polyalkylene oxides have for example the formula III

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R⁶, R⁷ are independently hydrogen, alkyl, alkenyl or aryl,

R^8th Hydrogen or methyl and

n is a whole number from 1 to 10,000. R⁶ and R⁷ preferably hydrogen, 0, -Or-alkyl, C₂-C₆Alkenyl or phenyl.

Preferred hydrogels are in particular polyacrylates, polymethacrylates and also the graft polymers described in US 4,931, 497, US 5,011, 892 and US 5,041, 496th

The swellable hydrogel-forming polymers are preferably crosslinked, that is, they comprise compounds having at least two double bonds which are in copolymerized into the polymer network. Particularly suitable crosslinkers are N, N'-methylenebisacrylamide and N, N'-methylene bis-methacrylamide, esters of unsaturated mono- or polycarboxylic acids of polyols, such as diacrylate or triacrylate, for example butanediol or ethylene glycol diacrylate or trimethylolpropane triacrylate and Allylverbin- compounds such as allyl (meth) acrylate, triallyl maleate, polyallyl esters, tetraallyloxyethane, triallylamine, tetraallylethylenediamine, allyl esters of phosphoric acid and also vinylphosphonic acid derivatives as described for example in EP-A-0 343,427th Also usable in the present process are hydrogels which are prepared using Polyallylethem as crosslinkers and by acidic homopolymerization of acrylic acid. Suitable crosslinkers are pentaerythritol tetraallyl, polyethylene glycol diallyl ether, Ethylenglykoldial- lylether.'Glyceroldi- and triallyl ether, polyallyl ethers based on sorbitol, and ethoxilier- te variants thereof.

The preferred methods of making the base polymer used in the process according to the invention are described in "Modern Superabsorbent Polymer Technology", FL Buchholz and AT Graham, Wiley-VCH, 1998, pages 77 to 84th Particularly preferred Bassispolymere that described in the compounder, such as in WO-A-01/38402, or described on a belt reactor as described for example in EP-A-0 955 086 are produced.

The water-absorbing polymer is preferably a polymeric acrylic acid or a polyacrylate. The preparation of this water-absorbing polymers can be prepared by a method known from the literature. Preferred are polymers, crosslinking comonomers in amounts of from 0.001 to 10 mol%, preferably 0.01 to 1 mol%, but most preference is given to polymers which were obtained by free-radical polymerization using a polyfunctional ethylenically unsaturated radical crosslinker which additionally bears at least one free hydroxyl group (such as pentaerythritol triallyl or trimethylolpropane).

The swellable hydrogel-forming polymers can be prepared by per se known polymerization process. Preference is given to polymerization in aqueous solution by the process known as gel polymerization. Here are two for example 15 to 50 wt .-% aqueous solutions of one or more hydrophilic monomers and optionally of a suitable grafting base in the presence of a radical initiator, preferably without mechanical mixing, utilizing the Trommsdorff Norrish effect (Makromol. Chem. 1, 169 (1947)) is polymerized. The polymerization reaction can in the temperature range between 0 and 150 ° C, preferably between 10 and 100 ° C, are carried out not only at atmospheric pressure but also at elevated or reduced pressure. As usual, the polymerization can also in a protective gas atmosphere, preferably under nitrogen, are executed to initiate the polymerization energy electromagnetic rays or the customary chemical polymerization initiators, for example organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketone peroxide, cumene hydroperoxide , azo compounds such as azodiisobutyronitrile and also inorganic peroxo compounds such as (NH)₂S₂O_8th or K₂S₂O_8th or H₂O₂, You can, optionally in combination with reducing agents such as sodium bisulfite and iron (II) sulfate or redox systems containing as reducing component an a-aliphatic and aromatic sulfinic acid, such as benzene and toluene sulfinic acid or derivatives thereof, such as Mannich adducts of sulfinic acids, aldehydes and amino compounds, such as are described in DE-A-1301 566, is used. By subsequently heating the polymer gels in the temperature range 50 to 130 ° C, preferably 70 to 100 ° C, the quality properties of the polymers can be further improved.

The gels obtained are, for example, 0 to 100 mol%, preferably 25 to 100 mol% and more preferably 50 to 85 mol%, based neutralized to monomer used, for which the customary neutralizing agents can be used, preferably alkali metal hydroxides or oxides , but more preferably sodium hydroxide, sodium carbonate and sodium bicarbonate.

Typically, the neutralization by mixing in the neutralizing agent as an aqueous solution or else preferably as a solid. The gel is mechanically comminuted, for example by means of a meat grinder, and the neutralizing agent is sprayed, sprinkled or poured on and then carefully mixed in. The gel mass obtained can be repeatedly minced for homogenization. The neutralized gel mass is then located with a belt or can dryer dried until the residual moisture content is preferably below 10 wt .-%, especially below 5 wt .-%. The dried hydrogel is then ground and sieved, typically including roll mills, pin mills or swing mills for the grinding. The particle size of the sieved hydrogel is preferably in the range from 45 to 1000 .mu.m, more preferably from 45-850 microns, most preferably 100 to 800 microns and more preferably at 100 to 700 microns. Postcrosslinking of hydrogels and superabsorbents is usually performed so that a solution of the surface postcrosslinker is sprayed onto the dry base polymer powder. Following spraying, the polymer powder is thermally dried, and the crosslinking reaction can take place either before or during the drying.

Preference is given to spraying a solution of the crosslinker in reaction mixers or mixing and drying systems such as Lodige.RTM mixer BEPEX®- mixer NAUTA® mixer SCHUGGI® mixer NARA® dryer and PROCESSING SALL®. Moreover, fluidized bed dryers can be used.

Drying may take place in the mixer itself, by heating the jacket or blowing in warm air. Equally suitable is a downstream dryer, for example a tray dryer, a rotary tube oven or a heatable screw. But it can also, for example, an azeotropic distillation as a drying process.

Preferred drying temperatures are in the range 50 to 250 ^CC, preferably at 50 to 200 ° C, and particularly preferably at 50 to 150 ° C. The preferred residence time at this temperature in the reaction mixer or dryer is below 30 minutes and more preferably below 10 minutes.

The crosslinking agent is preferably dissolved in not self-reactive solvents, preferably in lower alcohols such as methanol, ethanol, propane, ethylene glycol, most preferably in aqueous solutions of such suitable alcohols, where the alcohol content of the solution is 10 to 90 wt .-%, is particularly preferably from 40 to 60% by weight.

The crosslinking agent is used here in an amount of 0.01 to 1 wt .-%, based on the one set polymer and the crosslinker solution itself in an amount of 1 to 20 wt .-%, preferably 5 to 15 wt. -%, based on the polymer used.

The AUL 0.7 psi value [g / g] of the postcrosslinked water-absorbing polymers of the invention can by the method described in DE-A-199 09 653 to be measured and is preferably greater than 10, particularly greater than 15, more preferably greater than 20, in particular greater than 25, more preferably above 30th

The inventive post-treated aqueous fluid absorbent hydrogels are particularly suitable for thickening aqueous solutions and / or suspensions, preferably for thickening aqueous waste solutions and / or waste suspensions, such as medical and / or radioactive waste, most preferably for thickening medical waste solutions and / or more preferably for thickening medical Abfassungen and / or waste suspensions.

However, the inventive post-treated aqueous fluid absorbent hydrogels are also suitable for absorbing blood and / or body fluids in hygiene articles, such as incontinence products, sanitary napkins, tampons, liners. For this purpose, according to the invention post-treated aqueous liquids absorbing hydrogels with fibers, such as cellulose, as well as non-woven fabric can be made into absorbent composites.

A treatment with hydrophobic and hydrophilic materials in the treatment at least partially liquid waste, inbesonderere at least partially liquid medical waste, a uniform distribution of the superabsorbent reached in the container, wherein at least floating part of the superabsorbent at the beginning on the surface of the solution.

According to the invention are also mixtures of products made by the inventive process having biocidal, antimicrobial and / or antibacterial substances and / or perfume or fragrances, stabilizers, dyes, pH indicators and / or other auxiliaries.

To determine the quality of the after-treatment according to the invention, the dried hydrogel is tested using the test methods described below:

Methods:

Blood absorption (BA):

This method is used to determine the blood absorption of superabsorbents within 30 minutes.

Experimental setup:

Plastic container, round, internal diameter 50 ± 0.2 mm, internal height 20 + 0.2 mm (container I) plastic cylinder with a power supply (400 mesh = 36 microns sized holes), inside diameter 25 ± 0.2 mm, height of 40 ± 0.2 mm (container II) petri dish with lid, diameter 140 mm, height 75 mm stopwatch - analytical balance with an accuracy of + 0.0001. Defibriniert.es sheep blood of Oxoid GmbH, D-46467 Wesel Experimental procedure:

0.2 g superabsorbent are then weighed into the vessel II, its curb weight was preordained. Container I is charged with 15 g of defibrinated sheep blood. Container ter II is then placed in container I put this structure in the petri dish, the Petri dish sealed by the lid and start the timer. After a period of 30 minutes tank II is taken out of the container I, purified the outer side of the tank II with a cloth and the weight of the container II then determined. The difference this weight and the empty weight of container II and the superabsorbent composition employed (0.2 g) is calculated, the absorbed amount of blood and from the blood absorption.

Calculation: absorption of blood [g]. , , - = Blood absorption [g / g] initial mass superabsorbent [g]

Setting time (Solidification Time ST):

This method serves as a laboratory method for determining the time about need a superabsorbent to solidify 2 liters of a 0.9 wt .-% strength NaCl solution and thus represents the spec laboratory test the thickening of hospital or medical waste.

Experimental setup:

Cylindrical glass container with an inner diameter of 12 cm, a height of 28 cm and an internal volume of 3 liters 2 liters 0.9 wt .-% NaCl solution, prepared by dissolving 90 g NaCl in 9910 ml of deionized water - Stopwatch

Experimental procedure:

The glass container is charged with 2 liters of the 0.9 wt .-% NaCl solution. Subsequently, 67 g superabsorbents are added all at once to the solution and the time taken to complete solidification of the solution. Swimming behavior (SV):

The swimming behavior of the to be tested superabsorbent is determined together with the solidification time. During the measurement, while a visual working atmosphere is performed.

Superabsorbent polymer particles floating on the liquid surface, sources from the liquid surface in the direction of the container bottom. Superabsorbent particles that sink to the bottom, sources starting from the container bottom toward liquid surface.

A swimming behavior of 0% is defined as all superabsorbent particles immediately sink to the bottom and which is thickened to be thickened liquid exclusively starting from the container bottom. The swelling front migrates from the container bottom to the liquid surface.

A swimming behavior of 100% is defined as all superabsorbent particles float on the liquid surface and to be thickened liquid is only starting thickened from the liquid surface. The swelling front migrates from the liquid surface to the vessel bottom.

A swimming behavior of 50% is defined so that the superabsorbent polymer particles partially immediately sink to the bottom and partially floating on the liquid surface, so that the two meet keitsoberfläche source fronts in the middle between tank bottom and liquid.

Examples

Examples 1 to 31:

In a Lodige.RTM plowshare mixer type M5 / 20 laboratory batch mixer 1 kg of commercially available aqueous liquids were presented absorbent hydrogel (Hysorb F) and

if necessary, the indicated amount of aluminum sulfate as 26.8 wt .-% aqueous solution sprayed and mixed in for 10 minutes and

the specified amount of Aerosil® R 812, Aerosil® R974, Aerosil® R 8200 and / or Aerosil® optionally added 200 and mixed in for 15 minutes and

possibly sprayed the specified amount of Span® 80 as 25 wt .-% solution in diethylene glycol monobutyl ether and mixed in for 10 minutes. The speed of the mixer was 125 U / min.

In the examples, in which the aqueous aluminum sulfate solution was sprayed, was additionally dried. was dried at 70^CC, a pressure of 150 mbar and a residence time of 16 hours. Drying was aided by a gas flow of 200 l / h of nitrogen.

The results are summarized in the following table.

Table 1: Examples based HySorb® F

<img id="imgf000021_0001" he="224" wi="156" file="imgf000021_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="yes" /> Table 1 (continued): Examples based HySorb® F

<img id="imgf000022_0001" he="170" wi="161" file="imgf000022_0001.tif" img-format="tif" img-content="table" orientation="portrait" inline="yes" />

HySorb® Q. superabsorbent hydrogel (BASF Aktiengesellschaft, Germany)

Aerosil® R 812: fumed silica (Degussa, DE)

Aerosil® R 974: hydrophobic fumed silica after (Degussa, DE)

Aerosil® R 8200: fumed silica (Degussa, DE)

Aerosil® 200: hydrophilic fumed silica (Degussa, DE)

Span® 80: sorbitan (Uniqema, NL)

The spraying with aluminum sulfate solution (Examples 6 to 8) results in a slightly improved blood absorption and to a somewhat shorter solidification time. The amounts required for this to aluminum sulphate are high. The swimming behavior of the treated with aluminum sulfate hydrogels is inadequate.

Although the mixing with hydophobierter fumed silica (Examples 9 and 10) leading to the floatable hydrogels, the blood absorption, however, is drastically deteriorated.

The spraying with Span® 80 (Examples 11 to 14) does not lead to improved product properties. This also applies to the blending with pyrogenic silica (Examples 30 and 31).

This does not perform the finishing operations on its own products with the properties of the invention.

By the post-treatment of the dried hydrogel with small amounts of hydrophobicized silica hydrogels were obtained with excellent swimming behavior. In Example 3 of polyethylene glycol was additionally 0.35 with an average molecular weight of 300 g / mol is added to the bonding of the silica particles to improve the hydrogel wt .-%.

The blending with fumed silica and fumed silica hydophobierter (Examples 4 and 5) leads to hydrogels with excellent swimming behavior.

The use of fumed silica together with aluminum sulfate solution (Examples 15 to 18) leads to increased blood absorption and a shorter solidification time. But the aftertreated hydrogels are not floatable. The use of Span® 80 together with aluminum sulfate solution (Examples 20 and 21) also leads to an increased blood absorption and a shortened setting time. But the aftertreated hydrogels are not floatable.

The use of Span® 80 together with fumed silica (examples 22 and 23) provides buoyant hydrogels. The disadvantage is that no Hydrogelanteile fall and that the solidification time is unchanged long.

the use of aluminum sulphate solution and hydrophobicized pyrogenic silica (examples 24 and 25) likewise leading to the floatable hydrogels. Once again, however, it is disadvantageous that no Hydrogelanteile fall. The blood absorption is slightly increased and the solidification time is shortened slightly.

The three-stage treatment a) spraying with aluminum sulfate solution, b) mixing down view with pyrogenic silica and c) spraying with Span® 80 solution (Example 19) results in a hydrogel with good swimming behavior and shorter solidification time. The blood absorption is reduced but compared to the initial product.

A particularly advantageous property profile is) hydrophobic fumed silica and d) spraying with Span® 80 solution (examples obtained with the four-stage aftertreatment a) spraying with aluminum sulfate solution, mixing with b) pyrogenic silica and c 26 to 29). The so aftertreated hydrogels exhibit a significantly improved blood absorption and optimal swimming behavior. The hydrogel floats partially on the solution and the swelling hydrogel thus blocks the Flüssigkeitspoberfläche upwards, on the other hand fall from Hydrogelanteile and lead due to the improved blood absorption in a very short setting time.