EP2209503A2

EP2209503A2 - Superabsorber comprising a virus-inhibiting additive

Info

Publication number: EP2209503A2
Application number: EP08804628A
Authority: EP
Inventors: Samantha Champ; Mirjam Herrlich-Loos
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-09-25
Filing date: 2008-09-24
Publication date: 2010-07-28
Also published as: WO2009040358A2; WO2009040358A3

Abstract

Disclosed is a composition containing superabsorber and at least one alkali C8 to C24 alkyl sulfate as a virus-inhibiting additive as well as the use thereof in hygiene articles.

Description

Superabsorber with antiviral additive

description

The present invention relates to superabsorbents having an antiviral additive, processes for their preparation and their use.

Superabsorbents are known. Also, for such materials, terms such as "high swellable polymer" "hydrogel" (often used for the dry form), "hydrogel-forming polymer", "water-absorbent polymer", "absorbent gelling material", "swellable resin", "water-absorbent resin These are crosslinked hydrophilic polymers, in particular polymers of (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable graft base, crosslinked cellulose or starch ethers, crosslinked carboxymethylcellulose partially cross-linked polyalkylene oxide or natural products swellable in aqueous liquids, such as guar derivatives, wherein water-absorbing polymers based on partially neutralized acrylic acid are the most widespread.The essential properties of superabsorbents are their ability to multiply their own weight of aqueous Liquids absorb and the liquid also under some

Not to give up pressure again. The superabsorber, which is used in the form of a dry powder, transforms into a gel when it absorbs liquid, with the usual absorption of water corresponding to a hydrogel. Crosslinking is essential for synthetic superabsorbers and an important difference to conventional pure thickeners, since it leads to the insolubility of the polymers in water. Soluble substances would not be useful as superabsorbent. By far the most important application of superabsorbents is the absorption of body fluids. Superabsorbents are used, for example, in infant diapers, adult incontinence products or feminine hygiene products. Other fields of application are, for example, those used as water-retaining agents in agricultural horticulture, as water storage for protection against fire, for liquid absorption in food packaging or, more generally, for the absorption of moisture.

If superabsorbents are used in the hygiene sector, they will use body fluids such as As urine or menstrual blood exposed. The body fluids remain there for a period of time until the hygiene product is disposed of. A commonly undesirable effect is that components of the superabsorbent may come into contact with users' skin or mucous membranes, since these fluids can dissolve such components and are then mobile to some extent in the hygiene product. After correspondingly frequent changing of the hygiene product leads to considerable effort, even cost, for the user or his carers, this skin contact is usually undesirable as well as inevitable. When selecting components of superabsorbers, this is respect, think highly of. However, superabsorbents often contain various additives to achieve certain properties. For example, it is known to provide superabsorbents with skin care additives such as chamomile extract.

The frequent odor nuisance due to bacterial degradation of nitrogen-containing compounds to ammonia or amines can be masked by perfuming, resulting ammonia or amines can be removed by absorption or reaction, and the microbial degradation can be inhibited, for example, by biocides or urease inhibitors. Some surfactants are usable. For example, EP 1 358 894 A1 teaches hygiene articles which may contain a number of odor-inhibiting additives, in particular anhydride groups, acid groups, cyclodextrins, biocides, surfactants having an HLB value less than 11, absorbents such as zeolite, clay, activated carbon, silicon dioxide or activated alumina, microorganisms which act as antagonists to undesirable odoriferous microorganisms, pH buffers or chelating agents.

According to the teaching of WO 97/37695 A1, certain surfactants, namely quaternary ammonium salts, are used as anti-caking agents against the caking tendency of superabsorbents. WO 01/25 290 A1 discloses mechanically stable superabsorbers, which after surface postcrosslinking and drying are mixed with water in order to adjust a certain water content. Optionally, a surfactant having an HLB value of at least 3 may be added to the water, among others Cs to C24 alkyl sulfonates or C8 to C24 alkyl sulfates, which are preferably used in the form of their alkali metal or trialkanol ammonium salts. As an example, triethanolammonium lauryl sulfate is called.

Surfactants are also used to improve the wettability of superabsorbents. An example of this is WO 01/70 287 A2, according to the teaching of which surfactants with a reactive and a non-reactive functional group are used.

No. 6,106,811 discloses a toothpaste which, in addition to uncrosslinked polysodium acrylate, also contains sodium lauryl sulfate as surfactant as dispersing agent.

No. 7,132,379 discloses paper tissues provided with a virucidal mixture of a carboxylic acid and a surfactant such as sodium lauryl sulfate.

J. Piret, A. Desormeaux and MG Bergeron report in Current Drug Targets 3 (2002), pp 17-30 on virucidal properties of sodium lauryl sulfate in intravaginal application in animal experiments and suggest sodium lauryl sulfate as a possible topical agent against viruses such as HI viruses. In addition to superabsorbers which contain bactericides or non-bactericidal urease inhibitors for odor prevention or superabsorbents which contain skin-care additives, there continues to be an interest in superabsorbents which serve as carriers of biocidal, in particular virucidal, active substances. Preferably, these active ingredients should not damage the skin or mucous membrane and should not be problematic when disposed of in the environment, in particular bactericidal action is undesirable. It is therefore still the object to find new, improved or other such superabsorber or superabsorbent containing compositions. These should also be stable on storage, neither discolor nor lose their odor-inhibiting properties, in particular even after prolonged storage. Undesirable side effects when in contact with the skin or in the environment should not occur. In addition, the superabsorbents or compositions should have good liquid absorption and retention properties, in particular desirable being fast swelling capacity, good liquid transport properties in the gel bed with simultaneously high absorption capacity, high gel strength and good electrolyte tolerance.

Accordingly, compositions containing superabsorbent and at least one alkali Cs to C24 alkyl sulfate have been found. In addition, a process for the preparation of such compositions has been found, hygiene articles containing such compositions and the use of alkali Cs to C24 alkyl sulfate as virus-inhibiting (virucidal) addition to superabsorbents.

Alkali Cs to C24 alkyl sulfates are known and common commodities. Particularly suitable are the linear alkyl sulfates of the general formula:

where M is an alkali metal and n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 , 21, 22 or 23. Preferably, n is 7, 8, 9, 10, 11, 12 or 13 and most preferably 9 or 1 1. In a most preferred form, n is 1 l, ie the alkali Alkyl sulfate is alkali dodecyl sulfate or more commonly called alkali lauryl sulfate. The alkali metal is lithium, sodium, potassium, rubidium or cesium, preferably sodium or potassium and most preferably sodium. The alkali Cs to C24 alkyl sulfates can be used as pure compound or as a mixture of various compounds.

In preferred form, sodium lauryl sulfate is used as the alkali metal Cs-bis-C24-alkyl sulfate, in a particularly preferred form only sodium lauryl sulfate as the only alkali metal Cs-C24 alkyl sulfate. Sodium lauryl sulfate is a common surfactant which has good foaming power, wetting power and detergency and, because of its low toxicity, is often used in cosmetics, especially for oral care. The composition according to the invention generally contains alkali Cs-C24-alkylsulfate in an amount of at least 10 ppm by weight, preferably at least 100 ppm by weight and more preferably at least 500 ppm by weight and generally not more than 5% by weight .-%, preferably at most 4 wt .-% and in a particularly preferred form at most 3 wt .-%. Examples of suitable amount range are about 0.1 to 2 wt .-% or 0.1 to 0.5 wt .-%.

When used in a hygiene article, the composition according to the invention can lead to a virus-inhibiting effect.

Apart from alkyl sulfate and superabsorber, the composition may contain other ingredients, additives, auxiliaries or other components. Preferably, it consists essentially (i.e., with insubstantial additives and / or adjuvants) of superabsorbent and alkyl sulfate, or consists of superabsorbent and alkyl sulfate. The superabsorbent optionally contains further superabsorbers, usually added additives or auxiliaries, for example dedusting agents, agents for improving the conveying properties or flowability of the superabsorbent.

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

Processes for the production of superabsorbents, also surface-postcrosslinked superabsorbers, are known. Synthetic superabsorbents are obtained, for example, by polymerization of a monomer solution containing

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

receive. Suitable monomers a) are, for example, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, or derivatives thereof, such as acrylamide, methacrylamide, acrylic esters and methacrylic acid esters. Particularly preferred monomers are acrylic acid and methacrylic acid. Very particular preference is acrylic acid.

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

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

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

Suitable crosslinkers b) are in particular N, N'-methylenebisacrylamide and N, N'-methylenebismethacrylamide, esters of unsaturated monocarboxylic or polycarboxylic acids of polyols, such as diacrylate or triacrylate, for example butanediol or ethylene glycol diacrylate or methacrylate, and trimethylolpropane triacrylate and allyl compounds, such as allyl (meth) acrylate, triallyl cyanurate, maleic acid diallyl esters, polyallyl esters, tetraallyloxyethane, triallylamine, tetraallylethylenediamine, allyl esters of phosphoric acid and vinylphosphonic acid derivatives, as described, for example, in EP 343 427 A2. Further suitable crosslinkers b) are pentaerythritol di-, pentaerythritol tri- and pentaerythritol tetraallyl ethers, polyethylene glycol diallyl ether, ethylene glycol diallyl ether, glycerol di- and glycerol triallyl ethers, polyallyl ethers based on sorbitol, and ethoxylated variants thereof. Useful in the process according to the invention are di (meth) acrylates of polyethylene glycols, wherein the polyethylene glycol used has a molecular weight between 300 and 1000. However, particularly advantageous crosslinkers b) are di- and triacrylates of 3 to 15 times ethoxylated glycerol, of 3 to 15 times ethoxylated trimethylolpropane, of 3 to 15 times ethoxylated trimethylolethane, especially di- and triacrylates of 2 to 6-fold ethoxylated glycerol or trimethylolpropane, 3-fold propoxylated glycerol or trimethylolpropane, and 3-times mixed ethoxylated or propoxylated glycerol or trimethylolpropane, 15-ethoxylated glycerol or trimethylolpropane, as well as 40-times ethoxylated glycerol, trimethylolethane or trimethylolpropane ,

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

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

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

The polymerization is optionally carried out in the presence of conventional polymerization. Suitable polymerization regulators are, for example, thio compounds, such as thioglycolic acid, mercaptoalcohols, for. B. 2-mercaptoethanol, mercaptopropanol and mercaptobutanol, dodecyl mercaptan, formic acid, ammonia and amines, eg. As ethanolamine, diethanolamine, triethanolamine, triethylamine, morpholine and piperidine.

The monomers (a), (b) and optionally (c) are, optionally in the presence of the water-soluble polymers d), in 20 to 80, preferably 20 to 50, in particular 30 to 45 wt .-% aqueous solution in the presence of polymerization initiators with each other (co) polymerized. As polymerization initiators it is possible to use all compounds which decompose into free radicals under the polymerization conditions, eg. As peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and the so-called redox initiators. Preference is given to the use of water-soluble initiators. In some cases, it is advantageous to use mixtures of different polymerization initiators, for. B. mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate. Mixtures of hydrogen peroxide and sodium peroxodisulfate can be used in any proportion. Suitable organic peroxides are, for example, acetylacetone peroxide, methyl ethyl ketone peroxide, tert.

Butyl hydroperoxide, cumene hydroperoxide, tert-amyl perpivalate, tert-butyl perpivalate, tert-butyl perohexanoate, tert-butyl perisobutyrate, tert-butyl per-2-ethylhexanoate, tert-butyl perisononanoate, tert-butyl permaleate, tert-butyl perbenzoate, tert. Butyl-3,5,5-trimethylhexanoate and tert-amylperneodecanoate. Further suitable polymerization initiators are azo initiators, eg. 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N-dimethylene) isobutyramidine dihydrochloride, 2- (carbamoylazo) isobutyronitrile and 4,4'-azobis (4 -cyanovaleriansäure). The polymerization initiators mentioned are used in conventional amounts, for. B. in amounts of 0.01 to 5, preferably 0.1 to 2 mol%, based on the monomers to be polymerized.

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

Preference is given to using a redox initiator consisting of hydrogen peroxide, sodium peroxodisulfate and ascorbic acid. For example, these components are used in the concentrations 1 ^■ 10 ^"2 mol% hydrogen peroxide, 0.084 mol% Natriumperoxo- disulfate and 2,5 ^■ ^10" used ³ mol% based on the monomers ascorbic acid.

The aqueous monomer solution may contain the initiator dissolved or dispersed. However, the initiators can also be fed to the polymerization reactor separately from the monomer solution.

The preferred polymerization inhibitors require dissolved oxygen for optimum performance. Therefore, the polymerization inhibitors before the polymerization By inerting, that is, flowing through with an inert gas, preferably nitrogen, are freed of dissolved oxygen. This is done by means of inert gas, which can be introduced in cocurrent, countercurrent or intermediate inlet angles. Good mixing can be achieved, for example, with nozzles, static or dynamic mixers or bubble columns. Preferably, the oxygen content of the monomer solution before polymerization is reduced to less than 1 ppm by weight, more preferably less than 0.5 ppm by weight. The monomer solution is optionally passed through the reactor with an inert gas stream.

The preparation of a suitable polymer and further suitable hydrophilic ethylenically unsaturated monomers a) are described, for example, in DE 199 41 423 A1, EP 686 650 A1, WO 01/45 758 A1 and WO 03/104 300 A1.

Superabsorbents are usually obtained by polymerization of an aqueous monomer solution and optionally subsequent comminution of the hydrogel. Suitable preparation methods are described in the literature. Superabsorbers are obtained, for example, by:

Gel polymerization in a batch process or tube reactor and subsequent comminution in a meat grinder, extruder or kneader, such as, for example, in

EP 445 619 A2 and DE 19 846 413 A1;

• Polymerization in the kneader, which is continuously comminuted by, for example, counter-rotating stirrer shafts, as described, for example, in WO 01/38 402 A1; Polymerization on the belt and subsequent comminution in the meat grinder,

Extruder or kneader as described, for example, in EP 955 086 A2, DE 38 25 366 A1 or US Pat. No. 6,241,928;

Emulsion polymerization, in which bead polymers of relatively narrow gel size distribution are already obtained, as described, for example, in EP 457 660 A1; In-situ polymerization of a fabric layer which has been previously sprayed with aqueous monomer solution in continuous operation and subsequently subjected to photopolymerization, as described, for example, in WO 02/94 328 A2, WO 02/94 329 A1).

With regard to details of the procedure, reference is hereby expressly made to the cited documents. The reaction is preferably carried out in a kneader or on a belt reactor.

The preferred production process for superabsorbents, which is currently preferred for economic reasons, is continuous gel polymerization. In this case, a monomer mixture is first prepared by adding the neutralizing agent, optional comonomers and / or further auxiliaries to the acrylic acid solution in temporally and / or spatially separate addition sequence, and then adding the mixture to the Reactor is transferred, or is already presented in the reactor. The last addition is the metering of the initiator system to start the polymerization. In the subsequent continuous polymerization process, the reaction takes place to the polymer gel (ie, in the solvent of the polymerization - usually water - swollen to the gel polymer), which is already comminuted in the case of a stirred polymerization in advance. The polymer gel is then dried, if necessary, also crushed and sieved and transferred for further surface treatment.

The acid groups of the hydrogels obtained are usually partially neutralized, generally at least 25 mol%, preferably at least 27 mol% and more preferably at least 40 mol%, and generally at most 85 mol%, preferably at most 80 mol%. % and in a particularly preferred form at most 75 mol%, to which the customary neutralizing agents can be used, preferably alkali metal hydroxides, alkali metal oxides, alkali metal carbonates or alkali metal bicarbonates and mixtures thereof. Instead of alkali metal salts and ammonium salts can be used. Sodium and potassium are particularly preferred as alkali metals, but most preferably sodium hydroxide, sodium carbonate or sodium bicarbonate and mixtures thereof. Usually, the neutralization is achieved by mixing the neutralizing agent as an aqueous solution or preferably as a solid. For example, sodium hydroxide with a water content well below 50 wt .-% may be present as a waxy mass with a melting point above 23 ° C. In this case, a dosage as general cargo or melt at elevated temperature is possible.

The neutralization can be carried out after the polymerization at the hydrogel stage. However, it is also possible to carry out the neutralization to the desired degree of neutralization completely or partially before the polymerization. In the case of partial neutralization before the polymerization, at least 10 mol%, preferably at least 15 mol%, and generally at most 40 mol%, preferably at most 30 mol%, and more preferably at most 25 mol% of the acid groups are generally included in the neutralized prior to polymerization by adding a part of the neutralizing agent is already added to the monomer solution. The desired final degree of neutralization is in this case set only towards the end or after the polymerization, preferably at the stage of the hydrogel before it is dried. The monomer solution is neutralized by mixing in the neutralizing agent. The hydrogel can be mechanically comminuted in the neutralization, for example by means of a meat grinder or similar apparatus for comminuting gel-like masses, wherein the neutralizing agent is sprayed on, sprinkled or poured over and then thoroughly mixed. For this purpose, the gel mass obtained can be further gewolfft for homogenization. In a preferred embodiment, the monomer solution is adjusted to the desired final degree of neutralization prior to polymerization by addition of the neutralizing agent.

The gels obtained from the polymerization are optionally included for some time, for example at least 30 minutes, preferably at least 60 minutes and more preferably at least 90 minutes and generally at most 12 hours, preferably at most 8 hours and most preferably at most 6 hours a temperature of generally at least 50 ⁰ C and preferably at least 70 ⁰ C and generally held at most 130 ⁰ C and preferably at most 100 ⁰ C, which can often improve their properties even more.

The neutralized hydrogel is then dried with a belt or roller dryer until the water content ("residual moisture content", measuring method see below) is preferably below 15% by weight, in particular below 10% by weight up to 15% by weight of moisture, preferably at most 10% by weight, which is sufficient for the classification as "dry", in particular for handling as a powder (for example for pneumatic conveying, filling, screening or other process steps from solid process technology). ness. Alternatively, a fluidized bed dryer or a heated ploughshare mixer can be used for drying. To obtain particularly colorless products, it is advantageous in the drying of this gel to ensure rapid removal of the evaporating water. For this purpose, the dryer temperature must be optimized, the air supply and removal must be controlled, and it is in any case to ensure adequate ventilation. Naturally, the easier it is to dry, and the more colorless the product, the higher the solids content of the gel. The proportion of solvent in the polymerization is therefore adjusted so that the solids content of the gel prior to drying therefore generally at least 20 wt .-%, preferably at least 25 wt .-% and more preferably at least 30 wt .-% and generally at most 90% by weight, preferably at most 85% by weight and in a particularly preferred form at most 80% by weight. Particularly advantageous is the ventilation of the dryer with nitrogen or other non-oxidizing inert gas. Optionally, however, it is also possible simply to lower only the partial pressure of the oxygen during drying in order to prevent oxidative yellowing processes. As a rule, however, sufficient ventilation and removal of the water vapor also leads to an acceptable product. Advantageous in terms of color and product quality is usually the shortest possible drying time.

The dried hydrogel (which is no longer a gel (even if so often called), but a dry polymer with superabsorbent properties, which falls under the term "superabsorbent") is preferably ground and sieved, wherein for grinding usually roller mills, pin mills, hammer mills , Cutting mills or Swinging mills can be used. The particle size of the screened, dry hydrogel is preferably below 1000 .mu.m, more preferably below 900 .mu.m, most preferably below 850 .mu.m, and preferably above 80 .mu.m, more preferably above 90 .mu.m, most preferably above 100 .mu.m.

Very particular preference is given to a particle size (sieve cut) of 106 to 850 μm (measuring method see below).

The superabsorbent polymers prepared in this way are usually referred to as "base polymers" and are preferably subsequently surface-post-crosslinked The surface postcrosslinking can be carried out in a manner known per se with dried, ground and screened polymer particles For this purpose, compounds which react with the functional groups of the base polymer with crosslinking are usually applied in the form of a solution to the surface of the base polymer particles Suitable postcrosslinking agents are, for example:

Di- or polyepoxides, for example di- or polyglycidyl compounds such as phosphonic acid diglycidyl ether, ethylene glycol diglycidyl ether or bischlorohydrin ethers of polyalkylene glycols, alkoxysilyl compounds,

Polyaziridines, compounds containing aziridine units and based on polyethers or substituted hydrocarbons, for example bis-N-aziridinomethane,

Polyamines or polyamidoamines and their reaction products with epichlorohydrin,

Polyols such as ethylene glycol, 1,2-propanediol, 1,4-butanediol, glycerol, methyltriglycol, polyethylene glycols having an average molecular weight Mw of 200-10,000, di- and polyglycerol, pentaerythritol, sorbitol, the oxethylates of these polyols and their esters with carboxylic acids or carbonic acid, such as ethylene carbonate or propylene carbonate,

Carbonic acid derivatives such as urea, thiourea, guanidine, dicyandiamide, 2-oxazolidinone and its derivatives, bisoxazoline, polyoxazolines, di- and polyisocyanates,

Di- and poly-N-methylol compounds such as, for example, methylenebis (N-methylolmethacrylamide) or melamine-formaldehyde resins,

• Compounds with two or more blocked isocyanate groups such as trimethylhexamethylene diisocyanate blocked with 2,2,3,6-tetramethylpiperidinone-4.

If necessary, acid catalysts such as p-toluenesulfonic acid, phosphoric acid, boric acid or ammonium dihydrogen phosphate may be added. Particularly suitable postcrosslinkers are di- or polyglycidyl compounds such as ethylene glycol diglycidyl ether, the reaction products of polyamidoamines with epichlorohydrin, 2-oxazolidinone and N-hydroxyethyl-2-oxazolidinone.

The surface postcrosslinking (often only "postcrosslinking") is usually carried out in such a way that a solution of the surface postcrosslinker (often only "postcrosslinker") is sprayed onto the hydrogel or the dry base polymer powder.

The solvent used for the surface postcrosslinker is a customary suitable solvent, for example water, alcohols, DMF, DMSO and mixtures thereof. Particularly preferred are water and water / alcohol mixtures such as water / methanol, water / 1, 2-propanediol and water / 1, 3-propanediol.

The spraying of a solution of the postcrosslinker is preferably carried out in mixers with agitated mixing tools, such as screw mixers, paddle mixers, disk mixers, ploughshare mixers and paddle mixers. Vertical mixers are particularly preferred, plowshare mixers and paddle mixers are very particularly preferred. Suitable and known mixers include for example Lödige ^® - sawn pex ^® - Nauta ^® - Processall® ^® - and Schugi ^® mixer. Very particular preference high speed mixer lizer for example of the Schugi Flexomix ^® or Turbo ^®, are used.

After spraying the crosslinker solution may optionally follow a temperature treatment step, essentially to perform the surface postcrosslinking reaction (yet usually only referred to as "drying"), preferably in a downstream heated mixer ("dryer"), at a temperature of generally at least 50 ⁰ C, preferably at least 80 ⁰ C and in a particularly preferred form at least 100 ⁰ C and generally at most 250 ⁰ C, preferably at most 200 ⁰ C and in a particularly preferred form at most 150 ⁰ C. The average residence time (ie the average residence time of individual superabsorbent particles) of the superabsorbent to be treated in the dryer is generally at least 1 minute, preferably at least 3 minutes and more preferably at least 5 minutes and generally at most 6 hours, preferably 2 hours and most preferably at most 1 hour. In this case, not only the actual drying but also any existing cleavage products and solvent components are removed. The thermal drying is carried out in conventional dryers, such as tray dryers, rotary kilns or heatable screws, preferably in contact dryers. Preferably, the use of dryers in which the product is moved, ie heated mixers, particularly preferably paddle dryers, most preferably disc dryers. Suitable dryers include for example Bepex ^® -T dryers and Nara ^® -T Rockner. Moreover, fluidized bed dryers can also be used. The drying can also be done in the mixer itself done by heating the jacket or blowing a preheated gas such as air. However, it is also possible, for example, to use an azeotropic distillation as the drying process. The crosslinking reaction can take place both before and during drying.

In a particularly preferred embodiment of the invention, the hydrophilicity of the particle surface of the base polymers is additionally modified by the formation of complexes. The formation of the complexes on the outer shell of the particles is carried out by spraying solutions of divalent or polyvalent cations, wherein the cations can react with the acid groups of the polymer to form complexes. Examples of divalent or polyvalent cations are polymers which are formally wholly or partially composed of vinylamine monomers, such as partially or completely hydrolyzed polyvinylamide (so-called "polyvinylamine"), whose amine groups are always partially protonated to ammonium groups, even at very high pH values Metal cations such as Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Sc ³⁺ , Ti ⁴⁺ , Mn ²⁺ , Fe ²⁺ ^/ ³⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Y. ³⁺ , Zr ⁴⁺ , La ³⁺ , Ce ⁴⁺ , Hf ⁴⁺ , and Au ³⁺ Preferred metal cations are Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Ti ⁴⁺ , Zr ^4+, and La ³⁺ , and particularly preferred metal cations are Al ³⁺ , Ti ⁴⁺ and Zr ⁴⁺ The metal cations can be used both alone and in admixture with each other, of which all metal salts are suitable have sufficient solubility in the solvent to be used. Particularly suitable are metal salts with weakly complexing anions such as chloride, nitrate and Sulfate, hydrogen sulfate, carbonate, bicarbonate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate and carboxylate, such as acetate and lactate. In a particularly preferred form, aluminum sulfate is used. As solvents for the metal salts, water, alcohols, DMF, DMSO and mixtures of these components can be used. Particularly preferred are water and water / alcohol mixtures such as water / methanol, water / 1, 2-propanediol and water / 1, 3-propanediol.

The treatment of the base polymer with solution of a mono- or polyvalent cation is carried out in the same way as with surface postcrosslinkers, including the optional drying step. Surface postcrosslinker and polyvalent cation can be sprayed in a common solution or as separate solutions. The spraying of the metal salt solution onto the superabsorbent particles can take place both before and after the surface postcrosslinking. In a particularly preferred method, the spraying of the metal salt solution is carried out in the same step by spraying the crosslinker solution, wherein both solutions are sprayed separately successively or simultaneously via two nozzles, or crosslinker and metal salt solution can be sprayed together via a nozzle.

If a drying step is carried out after the surface postcrosslinking and / or treatment with complexing agent, it is advantageous, but not absolutely necessary, to cool the product after drying. The cooling can be carried out continuously or discontinuously, conveniently the product is continuously conveyed to a downstream of the dryer cooler. Any apparatus known for removing heat from powdered solids may be used for this purpose, in particular any apparatus mentioned above as a drying apparatus, unless it is supplied with a heating medium but with a cooling medium, such as cooling water, so that over the walls and depending on the construction no heat is also introduced into the superabsorber via the stirring elements or other heat exchange surfaces, but is removed therefrom. Or Bepex ^® coolers - the use of coolers in which the product is moved, that is, cooled mixers, examples of playing paddle coolers, disk coolers or paddle coolers, for example Nara ^® is preferred. The superabsorber can also be cooled in the fluidized bed by blowing in a cooled gas such as cold air. The conditions of the cooling are adjusted so that a superabsorbent is obtained with the temperature desired for further processing. Typically, an average residence time in the condenser of generally at least 1 minute, preferably at least 3 minutes and more preferably at least 5 minutes, and generally at most 6 hours, preferably 2 hours and most preferably at most 1 hour is set and the cooling capacity such that the product obtained has a temperature of generally at least 0 ⁰ C, preferably at least 10 ⁰ C and more preferably at least 20 ⁰ C and generally at most 100 ⁰ C, preferably at most 80 ⁰ C and more preferably Form has at most 60 ⁰ C.

Optionally, a further modification of the superabsorbents by admixing finely divided inorganic solids, such as silica, alumina, titanium dioxide and iron (II) oxide take place, whereby the effects of the surface treatment are further enhanced. Particularly preferred is the admixture of hydrophilic silica or alumina with an average size of the primary particles of 4 to 50 nm and a specific surface area of 50-450 m ² / g. The admixture of finely divided inorganic solids is preferably carried out after the surface modification by crosslinking / complex formation, but can also be carried out before or during these surface modifications.

Optionally, superabsorbents are provided with other customary additives and auxiliaries which influence the storage or handling properties. Examples include stains, opaque additives to improve the visibility of swollen gel, which is desirable in some applications, additives to improve the flow behavior of the powder, surfactants or the like. Often the dedusting or dust binder is added to the superabsorbent. Dust-removing or dust-binding agents are known, for example polyether glycols such as polyethylene glycol having a molecular weight of from 400 to 20,000 g / mol, polyols such as glycerol, sorbitol, neopentyl glycol or trimethylolpropane, which are optionally ethoxylated 7 to 20 times, used. Even a finite water content of the superabsorbent can be adjusted by adding water, if desired.

The solids, additives and auxiliaries can each be added in separate process steps, but usually the most convenient method is to add them to the superabsorber in the cooler, for example by spraying a solution or adding it in finely divided solid or in liquid form.

The surface-postcrosslinked superabsorber is optionally ground and / or screened in the customary manner. Milling is typically not required here, but most often, the setting of the desired particle size distribution of the product, the screening of formed agglomerates or fine grain is appropriate. Agglomerates and fines are either discarded or preferably recycled to the process in a known manner and at the appropriate place; Agglomerates after comminution. The particle size of the superabsorbent particles is preferably at most 1000 .mu.m, more preferably at most 900 .mu.m, most preferably at most 850 .mu.m, and preferably at least 80 .mu.m, more preferably at least 90 .mu.m, most preferably at least 100 .mu.m. Typical sieve cuts are, for example, 106 to 850 μm or 150 to 850 μm.

The composition of the invention is prepared by adding at least one alkali C8-C24 alkyl sulfate to a superabsorbent. For this purpose, before or after the production of the superabsorber, at least one of the following steps is carried out:

i) mixing at least one alkali C8-C24 alkyl sulfate with a superabsorbent; ii) co-grinding at least one alkali C8-C24 alkyl sulfate with a superabsorbent; iii) spraying at least one alkali C 8 -C 24 -alkyl sulfate, optionally in a solvent, preferably water, dissolved on a superabsorbent and / or iv) superabsorbents prepared by polymerizing at least one monomer, adding at least one alkali C 8 C24 alkyl sulfate to the monomer solution or to the reaction mixture during the polymerization.

When mixing at least one alkali C8-C24 alkyl sulfate with a superabsorbent, the alkali C8-C24 alkyl sulfate or mixture of alkali C8-C24 alkyl sulfates with the superabsorbent (which may also be a base polymer before post-crosslinking) is any any kind mixed. Methods and apparatus for mixing are known. For example, the superabsorbent can be mixed with alkaline C8-C24 alkyl sulfate in the mixers and dryers mentioned above in the postcrosslinking, conveniently during postcrosslinking. Subsequent incorporation of the alkali C8-C24 alkyl sulfate is, however, also possible if it is present in sufficiently solid form. with softer, about waxy substances mixing can also be done under cooling.

When co-grinding at least one alkali C8-C24 alkyl sulfate and a superabsorbent, the type of milling is not limited. Suitable apparatus are known and have already been described above in the comminution of the base polymer. Conveniently, alkali C8-C24 alkyl sulfate is added during a grinding step in the production of the superabsorbent. For softer, waxy substances, the common milling can also be done under cooling

When spraying alkali C8-C24 alkyl sulfate, the type of spraying is also not limited. Alkali C 8 -C 24 -alkyl sulphate can be sprayed on as a melt (preferably as a fine spray mist) or preferably in the form of a solution, for example and preferably during the postcrosslinking of the base polymer in the mixers mentioned there, in which the surface postcrosslinker and / or the Metal salt solution is sprayed on. The solvent used is a suitable solvent, for example water, water / acetone mixtures, water / propylene glycol or water / 1,3-propanediol mixtures and the solvents and solvent mixtures mentioned in the postcrosslinking and metal salt treatment. The concentration of alkali C8-C24 alkyl sulfate in the solution is generally at least 0.5% by weight, preferably at least 1% by weight, and more preferably at least 2% by weight, and generally at most 30% by weight. -%, preferably at most 20 wt .-% and in a particularly preferred form at most 10 wt .-%. Conveniently, alkali C8-C24 alkyl sulfate is co-applied with surface postcrosslinker and optionally metal salt in the surface postcrosslinking step. Most of the solutions are sprayed on separate nozzles, provided that postcrosslinker, metal salt and alkali C8-C24-alkyl sulphate no unwanted reactions with each other, but they can also be sprayed in the form of a common solution.

In a further embodiment, a composition according to the invention is prepared by the processes described above, which has a higher proportion of alkali metal Cs-C24-alkyl sulfate, generally at least 1 wt .-%, preferably at least 5 wt .-% and in a particularly preferred form at least 10 wt .-% and generally at most 50 wt .-%, preferably at most 40 wt .-% and in a particularly preferred form at most 30 wt .-%. The composition thus obtained can then be diluted to the desired final content of alkali C8-C24-alkyl sulfate by mixing in conventional apparatuses with additional superabsorbent.

The composition according to the invention, if required to adjust the desired particle size distribution, is screened again after subsequent application of or mixing with C8-C24 alkyl alkali sulfate. In addition, hygiene articles containing the superabsorbent composition according to the invention were found. Hygiene articles according to the invention are, for example, those intended for use in cases of mild or severe incontinence, such as inserts for severe or mild incontinence, incontinence pants, in addition to winters, so-called "training pants" for babies and toddlers or even ladies' hygiene articles such as insoles Such sanitary articles are known.The hygiene articles according to the invention differ from the known ones in that they contain the composition according to the invention A process for the production of hygiene articles has additionally been found, which is characterized by the fact that in the production of the hygiene article Moreover, processes for the production of hygiene articles using superabsorbents, including those with additives, are known.

The present invention further relates to the use of the composition according to the invention in training pants for children (so-called "training pants"), shoe inserts and other hygiene articles for absorbing bodily fluids The composition according to the invention can also be used in other fields of technology. in which liquids, in particular water or aqueous solutions, are absorbed, for example storage, packaging, transport (as constituents of packaging material for water- or moisture-sensitive articles, for example for flower transport, also as protection against mechanical effects); Cat food); food packaging (transport of fish, fresh meat; absorption of water, blood in fresh fish or meat packages); medicine (wound plasters, water-absorbing material for burn dressings or for other weeping wounds), cosmetics k (carrier material for pharmaceutical chemicals and drugs, rheumatism, ultrasound gel, cooling gel, cosmetic thickener, sunscreen); Thickener for oil / water or water / oil emulsions; Textiles (moisture regulation in textiles, shoe inserts, for evaporative cooling, for example in protective clothing, gloves, headbands); chemical-technical applications (as a catalyst for organic reactions, for the immobilization of large functional molecules such as enzymes, as adhesives in agglomerations, heat storage, filtration aids, hydrophilic component in polymer laminates, dispersants, condenser); as an aid in powder injection molding, in construction and construction (installation, in clay-based plasters, as a vibration-inhibiting medium, aid in tunnel excavations in water-rich subsoil, cable sheathing); Water treatment, waste treatment, water separation (de-icer, reusable sandbags); Cleaning; Agribusiness (irrigation, retention of meltwater and dew precipitation, addition of compost, protection of forests against fungal / insect attack, delayed release of active substances into plants); for fire fighting or fire protection; Coextrusion agents in thermoplastic polymers (eg for the hydrophilization of multilayer films); Production of films and thermoplastic moldings that can absorb water (eg rain and condensation water-retaining films for agriculture; superabsorbent-containing films for preserving fruit and vegetables kept in moist films; superabsorbent-polystyrene coextrudates, for example for food packaging such as meat, fish, poultry, fruits and vegetables); or as a carrier substance in active ingredient formulations (pharmaceuticals, crop protection).

test methods

Centrifuge Retention Capacity ("CRC", "Centrifuge Retention Capacity"):

The Centrifuge Retention Capacity (CRC) is determined according to the test method No. 441.2-02 "Centrifuge Retention Capacity" recommended and available from EDANA (European Disposables and Nonwovens Association, Avenue Eugene Plasky 157, 1030 Brussels, Belgium).

water content

The water content is determined according to the test method No. 430.2-02 "Moisture Content" recommended and available from EDANA.

particle size

The particle size is determined according to the test method No. 420.2-02 "Particle size distribution" recommended and available from EDANA.

Claims

claims

1. A composition containing superabsorbent and at least one alkali Cs to C24 alkyl sulfate.

2. Composition according to claim 1, characterized in that it contains at least one alkali lauryl sulfate.

3. A composition according to claim 1, characterized in that it contains at least one sodium Cs to C24 alkyl sulfate.

4. A composition according to claim 2, characterized in that it contains sodium lauryl sulfate.

5. A composition according to any one of claims 1 to 4, characterized in that it contains alkali Cs to C24 alkyl sulfate in an amount of 10 ppm by weight to 10 wt .-%.

6. The composition according to any one of claims 1 to 4, marked thereby, that the superabsorbent a crosslinked polymer based teilneutralisierter

Acrylic acid is.

7. The composition according to claim 6, characterized in that the superabsorber is surface postcrosslinked.

8. A process for preparing a composition as defined in claims 1 to 7, characterized in that one carries out at least one of the following steps in the preparation of a superabsorbent:

i) admixing at least one alkali Cs to C24 alkyl sulphate; ii) co-grinding the superabsorbent with at least one alkali Cs to C24 alkylsulfate; iii) spraying at least one alkali Cs to C24 alkyl sulfate, dissolved in a solvent, onto the superabsorber and / or iv) in the case of superabsorbers prepared by polymerization of at least one monomer, adding at least one alkali Cs to C24 alkyl sulfate Monomer solution or to the reaction mixture during the polymerization.

9. Hygiene article, comprising a defined in claims 1 to 7 composition.

10. Sanitary article according to claim 9, characterized in that the hygiene article is intended for use in severe and / or mild incontinence.

1 1. Hygiene article according to claim 9, characterized in that the hygiene article is a feminine hygiene article.

12. A process for the preparation of hygiene articles, characterized in that at least one composition defined in claims 1 to 7 is used in the preparation.

13. Use of alkali Cβ to C24 alkyl sulfate as a virus-inhibiting additive to superabsorbents.

14. Use according to claim 12, characterized in that sodium lauryl sulfate is used as virus-inhibiting additive.