EP1415025A1

EP1415025A1 - Method for producing cellulose shaped bodies with super-absorbent properties

Info

Publication number: EP1415025A1
Application number: EP02767288A
Authority: EP
Inventors: Waldemar Dohrn; Reiner BÜTTNER; Carmen Knobelsdorf; Ingo Notz; Georg Werner; Edgar Herrmann; Michael SCHÜMANN
Original assignee: Stockhausen GmbH and Co KG; Chemische Fabrik Stockhausen GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2001-07-31
Filing date: 2002-07-31
Publication date: 2004-05-06
Also published as: DE10137171A1; WO2003012182A1; EA005872B1; KR20040028969A; CA2454420A1; JP2005507466A; US20040265612A1; KR100588280B1; AR034961A1; CA2454420C; CN1285775C; BR0211600A; PL365477A1; ZA200400764B; EA200400212A1; US7052775B2; CN1561411A

Abstract

The invention relates to a method for producing cellulose shaped bodies with a high water-retention capacity, according to the dry/wet extrusion method. According to said method, a solution of between 5 and 20 mass % cellulose in a tertiary amine oxide is formed, the solution is extruded, the extrudate is drawn in a non-precipitating medium and the shaped bodies are precipitated in an aqueous or alcoholic precipitation bath. The method is characterised in that a solution containing between 0.01 and 250 mass %, (in relation to the cellulose), of at least one super-absorber with a particle size of ≤ 100 νm is extruded. The fibres, films and composite materials thus formed are characterised by a high water-retention capacity and are suitable for producing sanitary products, nappies or disposable nappies, sanitary towels, tampons, incontinence products, absorbent plasters, coverings for wounds, dressings, bandages, cleaning cloths, moisture-absorbent clothing, bed undersheets, filter materials or filters, packaging materials or cable sheathing.

Description

Process for the production of cellulosic moldings with superabsorbent properties

The invention relates to a process for the production of cellulosic moldings, in particular fibers, filaments and films with superabsorbent properties by the dry-wet extrusion process by forming a solution of 5 to 20% by mass of cellulose in a water-containing tertiary amine oxide, extruding the solution, distorting the extrudate in a non-precipitating medium and the moldings precipitate in an aqueous or alcoholic precipitation bath. The invention also relates to a composite and products containing cellulosic molded articles produced by the process according to the invention, in particular hygiene products, preferably baby or disposable diapers, sanitary napkins, tampons, incontinence articles, absorbent plasters, wound coverings, bandages, bandages, wipes, moisture-absorbent clothing, in particular sportswear and sweat-absorbing protective clothing, bed pads, filter material or filters, packaging materials, in particular food packaging and cable sheathing, and the use of the composite for the production of the aforementioned products.

It is known to produce cellulosic moldings, in particular fibers and films, by deforming a solution of cellulose in amine oxide hydrate, preferably in N-methylmorpholine-N-oxide monohydrate, and with a non-solvent for the cellulose, preferably water or alcohol, e.g. Ethyl alcohol is coagulated. Different shapes and simultaneous orientation of the cellulose molecules result in products with a wide range of uses in textile and technical applications.

The patent application US 573 1083 describes the production of fibers with a high retention capacity of aqueous liquids. The patent describes the production of a carboxylmethylated cellulose fiber by the solution spinning process. The spun cellulose fiber is partially converted into carboxylmethyl cellulose fiber by post-treatment with alkali hydroxides and chloroacetic acid derivatives. The degree of substitution is at least 0.1 carboxylmethyl cellulose groups per glucose unit. Increasing degrees of substitution lead to higher swelling values and decreasing fiber strengths.

The invention has for its object to provide a process for the production of cellulosic moldings with high retention for aqueous liquids. Furthermore, a process for the production of cellulosic shaped articles, in particular fibers and films, is to be created which, owing to its high retention capacity for aqueous liquids, for the production of hygiene products, in particular baby or disposable diapers, sanitary napkins, tampons, incontinence articles, absorbent plasters, wound coverings, bandages , Bandages, wipes, moisture-absorbing clothing, preferably sportswear and sweat-absorbing protective clothing, bed pads, filter material or filters, packaging materials, in particular food packaging or cable sheathing are suitable. Further advantages result from the following description and the claims.

This object is achieved according to the invention by a process for the production of cellulosic moldings with a high water retention capacity by the dry-wet extrusion process, by producing a solution of 5 to 20% by mass of cellulose in a water-containing, tertiary amine oxide, extruding the solution, drawing the extrudate in one non-precipitating medium and precipitation of the shaped bodies in an aqueous or alcoholic precipitation bath, at least one superabsorbent polymer having a particle size of <100 μm being added to a solution or mash with 0.01 to 250% by mass, based on cellulose, and extruding and pre-extruding it - preferably in water or alcohol, e.g. B. ethyl alcohol coagulated.

In a preferred embodiment, the solution or mash with at least one superabsorbent polymer has a tertiary amine oxide in a concentration of at least 75%.

For the purposes of the present invention, superabsorbent polymers are understood as meaning water-insoluble, crosslinked polymers which represent three-dimensional polymer networks and are capable of swelling and forming hydrogels in large amounts of water, aqueous liquids and body fluids, such as For example, to take up urine or blood and to be able to hold back the amount of liquid absorbed even under the influence of external pressure.

Because of the aforementioned characteristic absorption properties of such crosslinked superabsorbent polymers, they are used wherever aqueous liquids have to be absorbed. Your area of application is therefore very diverse. For example, they are used in the personal care industry in the manufacture of hygiene articles, such as absorbent sanitary articles for child and adult hygiene in the form of baby diapers, sanitary napkins, tampons, incontinence articles and products for wound covering in which they are incorporated.

These absorption properties are also used in the packaging industry, in which nonwoven products, into which these water-swellable or superabsorbent polymers are incorporated, are used as packaging components, particularly in the form of absorbent pads for fish and meat trays.

Other areas of application are agricultural technology and agriculture and horticulture. There superabsorbent polymers are used as soil additives for water and nutrient storage, artificial soil for plant breeding and as root protection gels. In the cable industry and communications technology, such water-swellable polymers are used as liquid-absorbing components in current- or light-conducting cables.

Such superabsorbent polymers are commercially available. These are essentially crosslinked polyacrylic acids or crosslinked starch / acrylic acid graft copolymers in which the carboxyl groups can be partially neutralized with sodium or potassium ions.

These superabsorbent polymers are prepared by known processes, for example bulk polymerization, solution polymerization, spray polymerization, inverse emulsion and inverse suspension polymerization. The solution polymerization is preferably carried out in water as a solvent by polymerization or copolymerization of aqueous solutions of mixtures of monomers, in particular partially neutralized monoethylenically unsaturated acid groups, optionally further monomers copolymerizable therewith and optionally with water-soluble polymers suitable as a graft base and at least one crosslinking agent to give a polymer gel which is dried after mechanical comminution, optionally postcrosslinked and ground or sieved to a certain particle size. Such solution polymerization can be carried out continuously or discontinuously. Here the patent literature shows a wide range of possible variations with regard to the concentration ratios, temperatures, type and amount of initiators as well as a multitude of post-crosslinking options. Typical methods are described by way of example in the following patents and are hereby incorporated by reference into the description: US 4,076,663, US 4,286,082, DE 2706 135, DE 35 03458, DE 4020780, DE 4244 548, DE 4323001, DE 43 33 056, DE 44 18 818.

Alternatively, superabsorbent polymers can also be obtained via inverse suspension and emulsion polymerization processes, in which an aqueous monomer phase in an oil phase, e.g. can consist of cyclohexane, suspended with auxiliaries and then polymerized. The water in the polymer droplets is removed by azeotropic distillation and the polymer particles are then isolated by filtering off the oil phase. Surface crosslinking of the polymer particles can be carried out both in the suspension and subsequently on the isolated polymer powder. The principle of the method is described, for example, in the patents US 43 40706, DE 37 13601 and DE 28 40 010, which are hereby incorporated by reference into the description.

Such superabsorbent polymers are preferably polymerized by components a.) 55 to 99.95% by weight of monoethylenically unsaturated carboxyl-bearing monomers, b.) 0.05 to 5.0% by weight of at least one crosslinking agent, c.) 0 to 40% by weight of further monomers copolymerizable with a.), D.) 0 to 30% by weight of a water-soluble graft base, and the components a.) To d.) Add up to 100% by weight, where the polymers obtained can optionally be post-crosslinked at least once. Monoethylenically unsaturated carboxyl group-bearing monomers of component a.) Include, in particular, monoethylenically unsaturated C3 to C10 monocarboxylic acids and their alkali and / or ammonium and / or amine salts. These monomers include, for example, acrylic acid, methacrylic acid, dimethacrylic acid, ethyl acrylic acid, crotonic acid, isocrotonic acid, vinyl acetic acid and allylacetic acid. From this group, acrylic acid, methacrylic acid or their alkali metal or ammonium salts or mixtures thereof are used as preferred monomers, acrylic acid and its sodium, potassium or ammonium salts being particularly preferred as monomers.

Further monoethylenically unsaturated carboxyl groups-bearing monomers are also the monoethylenically unsaturated C ₄ to C ₈ dicarboxylic acids, their anhydrides or their alkali and / or ammonium and / or amine salts. Suitable dicarboxylic acids are, for example, maleic acid, fumaric acid, itaconic acid and methylene malonic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride and the corresponding sodium, potassium or ammonium salts of maleic or itaconic acid being preferred.

Monoethylenically unsaturated carboxyl-bearing monomers are also the hydrolyzates of (meth) acrylonitrile copolymers and of starch (meth) acrylonitrile

Graft copolymers, hydrolysates of (meth) acrylamide copolymers and saponification products of (meth) acrylic acid copolymers with ethylenically unsaturated esters as a polymer containing carboxylate groups.

The acidic, copolymerized monomer components of the superabsorbent polymers are preferably neutralized to at least 25 mol%, preferably to at least 50 mol% and particularly preferably to at least 75 mol% and are, as described above, for example as sodium, potassium or Ammonium salt or mixtures thereof.

Compounds which have at least two ethylenically unsaturated double bonds or one ethylenically unsaturated double bond and one or more functional groups reactive towards acid groups are usually used as crosslinking agents of component b.). Preferred crosslinking agents are those that have at least two ethylenic contain unsaturated double bonds, such as. B. methylene bisacrylamide or - methacrylamide or ethylene bisacrylamide, further esters of unsaturated mono- or polycarboxylic acids of polyols, such as diacrylates or triacrylates, for. B. butanediol or ethylene glycol diacrylate or methacrylate, trimethylolpropane triacrylate, and their alkoxylates with preferably 1 to 30 moles of ethylene oxide, also allyl compounds and their alkoxylates such as allyl (meth) acrylate, allyl (EO) ι- ₃ o (meth) acrylate , Triallyl cyanurate, maleic acid diallyl ester, polyallyl ester, tetraallyloxiethan, di- and triallyl amine, tetraallyl ethylenediamine, allyl ester of phosphoric acid or phosphorous acid. Compounds which have at least one functional group which is reactive towards acid groups are, for example, the N-methylol compounds of amides, such as methacrylamide or acrylamide and the ethers derived therefrom, but also di- and polyglycidyl compounds are to be mentioned here.

The crosslinking agents can be used alone or in combination in amounts of 0.05 to 5.0% by weight, preferably 0.05 to 2.0% by weight and particularly preferably 0.1 to 1.0% by weight , based on the monomers, are used.

In addition to the monoethylenically unsaturated carboxyl group-bearing monomers and the crosslinking agent (components a.) And b.)), Other comonomers which are largely soluble in the aqueous monomer solution for modifying the properties as component c.) May optionally be present in the production of superabsorbent polymers. Such comonomers can be, for example, (meth) acrylamide, (meth) acrylonitrile, vinyl pyrrolidone, vinyl acetamide, 2-acrylamido-2-methylpropanesulfonic acid, vinyl sulfonic acid, (meth) allylsulfonic acid, hydroxyethyl acrylate, alkylpolyethylene glycol (meth) acrylates, alkylaminoalkyl (meth) acrylates, alkylamino - be propylacrylamide, acrylamidopropyltrimethylammonium chloride or mixtures thereof. Such comonomers should not exceed a proportion of 40% by weight, since they can possibly impair the swellability of the resulting superabsorbent polymer.

In addition, the superabsorbent polymers can contain water-soluble polymers as component d.) As a graft base, which are optionally present in amounts of up to 30% by weight. These include partially or fully hydrolyzed polyvinyl alcohols, polyacrylic acids, polyglycols or their mixtures, polysaccharides such as starch or starch derivatives, cellulose or cellulose derivatives, but also polycarboxy polysaccharide. The latter are either derived from polysaccharides which do not naturally contain carboxyl groups and are provided with carboxyl groups by subsequent modification, or they already contain carboxyl groups by nature and are optionally subsequently provided with further carboxyl groups by modification.

The first group of polysaccharides includes, for example, starch, amylose, amylopectin, cellulose and polygalactomannans such as guar and carob flour, the second group includes e.g. Xanthans, alginates, gum arabic etc.

As already mentioned, the carboxyl groups are either present by their inherent molecular structure, for example by uronic acid units in the polysaccharide molecule, or are incorporated by subsequent modification with reagents containing carboxyl groups or are generated by oxidation reactions. Among the polycarboxypolysaccharides in which the carboxyl groups are incorporated by subsequent modification, carboxylalkyl derivatives are preferred, in particular the carboxymethyl derivatives. Among the polycarboxypolysaccharides in which the carboxyl groups are generated by oxidation of the polysaccharide molecule, oxidized starches and their derivatives are particularly preferred.

In addition to the carboxyl groups, polycarboxypolysaccharides can be modified with further groups, in particular those which improve water solubility, for example hydroxyalkyl, in particular hydroxyethyl, and phosphate groups.

Particularly preferred polycarboxypolysaccharides are carboxymethyl guar, carboxylated hydroxyethyl or hydroxypropyl cellulose, carboxymethyl cellulose and carboxymethyl starch, oxidized starch, carboxylated phosphate starch, xanthan and mixtures of the individual polycarboxypolysaccharides. In particular, carboxymethyl cellulose is preferably used.

Polycarboxypolysaccharide derivatives with low and high degrees of carboxyl substitution can be used. However, they usually have an average degree of carboxyl substitution in the range from 0.3 to 1.5, with polycar- boxypolysaccharide derivatives with a degree of substitution in the range from 0.4 to 1.2 are preferably used.

With regard to component d.) It should also be noted that the molecular weights of the polymers added as the graft base must be adapted to the conditions of the polymerization conditions. For example, in the case of aqueous solution polymerization it may be necessary to use only low or medium molecular weight polymers, while this factor only plays a minor role in suspension polymerization.

It is also known that the property profile of superabsorbent polymers can be improved by the process of subsequent surface crosslinking. During such post-crosslinking, the carboxyl groups of the polymer molecules on the surface of the superabsorbent polymer particles are crosslinked with crosslinking agents at an elevated temperature. Compounds which have at least two functional groups and which can crosslink the functional groups of the polymer on the surface of the polymer particles are used as postcrosslinking agents. Alcohol, amine, aldehyde, glycidyl, epichlor and isocyanate functions are preferred, crosslinking molecules also being used several different functions, but also polyvalent metal salt compounds can be used. Typical examples of postcrosslinking agents are: ethylene glycol, diethylene glycol, triethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanoiamine, sorbitan fatty acid ester, trimethylolpropane, pentaerythritol, polyvinyl alcohol, sorbitol, ethylene carbonate, propylene carbonate, polyepoxide Ethylene glycol diglycidyl ether, aziridines and polyisocyanates. Ethylene carbonate is preferably used as the post-crosslinking agent. The postcrosslinking agents are used in an amount of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.1 to 1.5% by weight, based on the polymer to be crosslinked, where appropriate the subsequent surface crosslinking can be repeated several times.

In the preparation of the polymers containing carboxylate groups to be used according to the invention, monomers bearing carboxyl groups can be, for example, acrylic acid, methacrylic acid, vinyl acetic acid, maleic acid or mixtures thereof. The use of acrylic acid alone or mixtures thereof is preferred. In addition to polymers which are obtained by crosslinking polymerization of partially neutralized acrylic acid, those which contain additional proportions of graft-polymerized starch and / or polyvinyl alcohol are preferably used.

Surprisingly, it was found that admixing superabsorbent polymers, as described above, to lyocell spinning solutions is possible without the polymers swelling and thereby impairing the spinnability of the solution or the spinning process as such. In particular, it was found that swelling of the superabsorbent polymers in aqueous amine oxide solutions virtually does not occur if the concentration of the amine oxide used, preferably N-methylmorpholine-N-oxide, approaches that of the corresponding monohydrate. According to the invention, the superabsorbent polymers are suspended in tertiary amine oxide or spinning solutions prepared therewith, the concentration of which is 75 to 90%. The concentration of the tertiary amine oxide is preferably between 80 and 88% and particularly preferably between 84 and 87%.

It was also surprising that the cellulosic moldings produced by the dry-wet extrusion process, in particular fibers and films, in which the above-described superabsorbent polymers are embedded, are very easily accessible to aqueous liquids, although it would have been expected that the incorporation of the Polymers in the cellulosic moldings lead to a significant reduction in their superabsorbent properties. However, this has not been observed.

According to the preferred embodiment of the method according to the invention, the solution used for extrusion contains 1 to 200% by mass, based on cellulose, of at least one superabsorbent polymer, preferably 1 to 150% by mass. Solutions which contain 1 to 100% by mass, based on cellulose, of at least one superabsorbent polymer are particularly preferred.

The grain size of the superabsorbent polymers used is preferably in the range <20 μm. Basically there is no restriction regarding the lower limit of the grain size of suitable polymers. Only suitable sieve lines with grain sizes of> 0.05 μm, 0.1 μm, 0.5 μm and 1 μm may be mentioned as examples.

Commercially available superabsorbent-absorbing polymers can be used, but their grain size is generally well above the range according to the invention. The grain size required for incorporation into the solution is achieved by grinding these commercially available polymers. The grain size of the superabsorbent polymers is expediently adjusted by grinding and sifting in a fluidized bed counter-jet mill with turboplex fine sifting.

Preferably, at least one superabsorbent polymer is used in the process according to the invention, by polymerization of the components

a.) 55 to 99.95% by weight of monoethylenically unsaturated carboxyl group-bearing monomers, which are optionally partially neutralized b.) 0.05 to 5.0% by weight of at least one crosslinking agent, c.) 0 to 40% by weight further monomers copolymerizable with a.), d.) 0 to 30% by weight of a water-soluble graft base, and the components a.) to d.) add up to 100% by weight.

Weakly pre-crosslinked, partially neutralized superabsorbent polymers which are post-crosslinked at least once are particularly preferred.

The extrudable solution loaded with the superabsorbent polymer can be formed in various embodiments. In a preferred embodiment of the process according to the invention, the solution or mash with at least one superabsorbent polymer has a tertiary amine oxide in a concentration of at least 75%. In one embodiment, at least one superabsorbent polymer is dispersed in the cellulose solution already formed.

In a further embodiment, at least one superabsorbent polymer is dispersed in preferably 85% N-methylmorpholine-N-oxide and this dispersion is added to the spinning solution already formed. This procedure has the advantage that it is easier to form the suspension of the fine-titer superabsorbent polymer in 85% N-methylmorpholine-N-oxide than to disperse it in the cellulose solution formed.

In both cases, the superabsorbent polymer is a uniform product or a mixture of several differently structured polymers. The polymer or the polymer mixture used is insoluble in the cellulose solution and is incorporated into the cellulose when it precipitates, resulting in a structure such that the superabsorbent polymer remains readily accessible to the aqueous liquid to be bound.

In general, fibers, filaments or foils are produced by the process according to the invention. You can work with round or profiled nozzle holes, hollow nozzles or slot nozzles. Solvents in the process according to the invention are tertiary amine oxides, with N-methylmorpholine-N-oxide monohydrate being a particularly preferred solvent.

The precipitated shaped body is then washed with water or aqueous alcoholic solutions to remove the amine oxide and dried.

By grinding and dispersing the superabsorbent polymers in the extrusion solution, cellulosic moldings, in particular fibers, filaments and foils can be created which, depending on the incorporated parts, show a different absorption capacity for aqueous liquids, as can be seen in diagram I (FIG. 1) , Fibers and filaments largely retain their textile character due to the homogeneous distribution of the super absorber over the entire fiber cross section. In particular, fibers and filaments with low proportions of incorporated superabsorbent polymers, preferably between 1 and 25%, can be processed further into nonwovens, yarns and fabrics by the known textile techniques. A blend with other fibers such as. B. polyester fibers is possible.

The object is further achieved by a composite material, in particular as a non-woven fabric, felt or yarn, which at least partially consists of the cellulosic shaped bodies, in particular fibers, which according to one of the claims of the invention. Process according to the invention have been produced. This composite can consist entirely of lyocell fibers produced according to the invention and loaded with superabsorbers. The composite can also be based on a mixture of different superabsorbent polymers modified cellulosic fibers, whereby a composite is obtained with similar effects as if a fiber material is loaded with two or more different superabsorbent polymers. Crosslinked copolymers of acrylic acid / sodium acrylate and crosslinked copolymers of isobutylene / maleic anhydride may be mentioned here as examples.

Finally, it is also possible to make a textile fabric from fibers loaded with superabsorbent polymers according to the invention and from normal Lyocell fibers or other fibers, such as. B. polyethylene, polypropylene, polyester, polyacrylic or cellulose.

The composite material according to the invention is suitable for use in the manufacture of hygiene articles, in particular baby or disposable diapers, sanitary napkins, tampons or incontinence articles, wound coverings, in particular absorbent plasters, bandages or bandages, wipes, moisture-absorbing articles of clothing, bed pads, filter materials or filters, packaging materials , especially food packaging and cable sheathing.

The textile fabrics according to the invention can, for. B. in moisture absorbing garments, e.g. be used in sportswear and in sweat-absorbing protective clothing.

The invention furthermore relates to hygiene articles, in particular baby or disposable diapers, sanitary napkins, tampons or incontinence articles, wound coverings, in particular absorbent plasters, bandages or bandages, wipes, moisture-absorbing clothing, bed sheets, filter materials or filters, packaging materials, in particular food packaging, cable sheathing, which contain cellulosic moldings which have been produced according to one of the claims of the process according to the invention. The following examples serve to further clarify the process according to the invention and the properties relevant to the use of the process products:

Example 1 :

A 12 mass% cellulose solution in N-methylmorpholine-N-oxide monohydrate is a powdery superabsorbent polymer based on a weakly pre-crosslinked copolymer of acrylic acid and sodium acrylate, which has been subjected to surface post-crosslinking, with a grain size <15 μm in a weight fraction of 5% by mass, based on the cellulose proportion, added. This spinning solution is homogenized in a kneader and spun at a temperature of approx. 90 ° C through a spinneret with 330 holes and a nozzle hole diameter of 140 μm. The take-off speed is 25 m / min. The multi-thread is passed through several wash baths to remove the N-methylmorpholine-N-oxide. The thread is cut into stacks of 40 mm, dried at approx. 80 ° C.

The fibers have a titer of 0.17 tex, an elongation of 10.8% and a tensile strength of 42.3 cN / tex. The water pressure retention capacity according to DIN 53814 is 97%.

Example 2:

A suspension of a superabsorbent polymer based on a crosslinked copolymer of acrylic acid and sodium acrylate in 85% N-methylmorpholine-N-oxide is added in such a concentration to a 10% by mass cellulose solution in N-methylmorpholine-N-oxide monohydrate, that the spinning solution contains 10% by mass of cellulose and 50% by mass of the polymer based on the proportion of cellulose. The grain size of the suspended superabsorbent polymer was <15 μm. After homogenization, the spinning solution according to Example 1 is spun. The thread is cut into stacks of 40 mm and dried at approx. 80 to 90 ° C. The fibers have a titer of 0.50 tex, an elongation of 12.6% and a tear strength of 23.1 cN / tex. The water pressure retention capacity according to DIN 53814 is 515%.

Example 3:

A 9% by mass cellulose solution in N-methylmorpholine-N-oxide monohydrate is a suspension of a superabsorbent polymer based on a crosslinked

Copolymers of acrylic acid and sodium acrylate in 85% N-methylmorpholine-N-

Added oxide in such a concentration that the spinning solution contains 9% by mass of cellulose and, based on the proportion of cellulose, 90% by mass of the polymer. The grain size of the suspended superabsorbent polymer was <15 μm. After homogenization, the spinning solution according to Example 1 is spun. After the N-methylmorpholine-N-oxide has been washed out, part of the washing water is removed from the fiber cable by squeeze rollers. In a subsequent bath, the preparation, repeated squeezing, cutting of the cable to a stack length of 40 mm and drying at 80 to 90 ° C takes place.

The fibers have a titer of 0.50 tex, an elongation of 16.2% and a tensile strength of 12.6 cN / tex. The water pressure retention capacity according to DIN 53814 is 945%.

Example 4:

A spinning solution prepared according to Example 3 is spun at a temperature of approximately 90 ° C. through a spinneret with 128 holes and a nozzle hole diameter of 90 μm in 50% ethyl alcohol. The multifilament thread is passed through several wash baths with 50% ethyl alcohol to remove the N-methylmorpholine-N-oxide. The thread is cut into stacks of 40 mm, dried at approx. 80 ° C.

The fibers have a titer of 0.40 tex, an elongation of 15.8% and a tensile strength of 12.4 cN / tex. The fibers spun according to Example 4 show advantages in the carding process, in particular in the case of fibers highly filled with superabsorbent polymers, because the filaments adhere very little to one another. The water pressure retention capacity according to DIN 53814 is 930%. Example 5:

A 10% by mass cellulose mash in 80% N-methylmorpholine-N-oxide is a suspension of a mixture of two superabsorbent polymers, one based on a crosslinked copolymer of acrylic acid / sodium acrylate and a crosslinked copolymer of isobutylene / maleic anhydride in 85% N-methylmorpholine-N-oxide added. The suspension contains the two copolymers in equal parts. The grain size of both copolymers is <15 μm. The proportion by weight of both superabsorbent polymers is 30% by mass, based on the proportion of cellulose. After the water has been distilled off to the N-methylmorpholine-N-oxide monohydrate and the cellulose has dissolved, the spinning solution according to Example 1 is spun.

The fibers have a titer of 0.50 tex, an elongation of 13.3% and a tensile strength of 23.0 cN / tex. The water pressure retention capacity according to DIN 53814 is 320%.

Example 6:

A spinning solution prepared according to Example 3 is formed at a temperature of approx. 90 ° C. through a slot nozzle into a film with a thickness of approx. 40 μm in the dried state. The nozzle slot had a length of 62.8 mm and the distance between the nozzle and the aqueous precipitation bath was 10 mm. After the air gap, the film emerging from the nozzle was passed through 2 washing baths of 6 m length to remove the N-methylmorpholine-N-oxide and wound up. The film was dried at 60 ° C. The water retention capacity of this film according to DIN 53814 was 1050%. Example 7:

Fibers that were produced according to Example 2 are processed through the processing steps of opening, carding, paneling and needling on a needle-punching machine to needle-punching with a basis weight of 150 g / m ² . The water pressure retention capacity corresponds to that of example 2.

Example 8:

Fibers with a titer of 0.17 tex, which were produced in accordance with Example 1, are processed into yarns according to the cotton technology on ring spinning machines. The ring yarns with a fineness of 15 tex at 854 Dr / m have a tensile strength of 22 cN / tex with an elongation of 7.5%. The water pressure retention capacity according to DIN 53814 corresponds to that of Example 1.

Example 9:

Fibers with a titer of 0.17 tex, which were produced in accordance with Example 1, are mixed in equal parts with polyester fibers of the same titer and processed into yarns according to the cotton technology on the ring spinning machine. The ring yarns have a fineness of 17.3 tex, 876 dr / m and a tensile strength of 25 cN / tex. The elongation at break is 9.6%. The water pressure retention capacity according to DIN 53814 is 62%.

Claims

claims

1. Process for the production of cellulosic moldings with high water retention capacity by the dry-wet extrusion process by producing a solution of 5 to 20% by mass of cellulose in a water-containing, tertiary amine oxide, extruding the solution, drawing the extrudate in a non-precipitating medium and Precipitation of the shaped bodies in an aqueous or alcoholic precipitation bath, characterized in that a solution or the mash with 0.01 to 250% by mass, based on cellulose, of at least one superabsorbent polymer having a particle size of <100 μm is added and extruded.

2. The method according to claim 1, characterized in that the solution or mash with at least one superabsorbent polymer is a tertiary

Has amine oxide in a concentration of at least 75%.

3. The method according to claim 1 or 2, characterized in that the solution contains 1 to 200 mass%, preferably 5 to 100 mass%, based on cellulose, at least one superabsorbent polymer.

4. The method according to any one of claims 1 to 3, characterized in that the grain size of the superabsorbent polymer is in the range <25 microns.

5. The method according to any one of claims 1 to 4, characterized in that the superabsorbent polymer by polymerizing the components a.) 55 to 99.95 wt .-% monoethylenically unsaturated carboxyl-bearing monomers, which are optionally partially neutralized b.) 0.05 up to 5.0% by weight of at least one crosslinking agent, c.) 0 to 40% by weight of further monomers copolymerizable with a.), d.) 0 to 30% by weight of a water-soluble graft base, and the constituents a .) to d.) add up to 100% by weight, is available.

6. The method according to any one of claims 1 to 5, characterized in that the superabsorbent polymers are post-crosslinked at least once.

7. The method according to any one of claims 1 to 6, characterized in that at least one superabsorbent polymer is dispersed in the cellulose solution.

8. The method according to any one of claims 1 to 7, characterized in that a solution of cellulose, amine oxide and water is prepared, at least one superabsorbent polymer is suspended in N-methylmorpholine-N-oxide monohydrate, the suspension of the solution is added and homogenized.

9. The method according to any one of claims 1 to 8, characterized in that a solution is prepared from cellulose, amine oxide and water, at least one superabsorbent polymer is suspended in 85% N-methylmorpholine-N-oxide, the suspension of the solution is added, water distilled and homogenized until the N-methylmorpholine-N-oxide monohydrate was reached.

10. The method according to any one of claims 1 to 9, characterized in that fibers, filaments or foils are produced.

11. The method according to claim 10, characterized in that the fibers, filaments and foils precipitate in an alcoholic spinning bath.

12. The method according to any one of claims 1 to 11, characterized in that one forms a cellulose solution in N-methylmorpholine-N-oxide monohydrate.

13. The method according to any one of claims 1 to 12, characterized in that the precipitated shaped bodies are washed and aftertreated.

14. The method according to any one of claims 1 to 13, characterized in that the grain size of the superabsorbent polymers is adjusted by dry grinding and sifting in a fluidized bed counter-jet mill with turboplex fine sifting.

15. Composite, in particular as a textile fabric, tow, fleece, felt or yarn, which consists at least partially of the method according to one of claims 1 to 14 fibers produced.

16. The composite according to claim 15, which consists of superabsorbent-loaded fibers and lyocell fibers.

17. A composite according to claim 15, which consists of fibers loaded with superabsorbent polymers and at least one further textile fiber made of polyethylene, polypropylene, polyester, polyacrylic or cellulose.

18. Use of the composite according to claims 15 to 17 for the production of hygiene products, baby or disposable diapers, sanitary napkins, tampons, incontinence articles, absorbent plasters, wound coverings, bandages,

Bandages, wipes, moisture-absorbing clothing, bed sheets, filters, packaging materials or cable jackets.

19. Hygiene articles, in particular baby or disposable diapers, sanitary napkins, tampons or incontinence articles, which contain cellulosic molded articles which are produced by the process according to one of claims 1 to 14.

20. Wound covers, in particular absorbent plasters, bandages or bandages, which contain cellulosic molded articles which are produced by the method according to one of claims 1 to 14.

21. wipes containing cellulosic molded articles which are produced by the method according to any one of claims 1 to 14.

22. Moisture-absorbing clothing, in particular for sportswear and sweat-absorbing protective clothing, which contain cellulosic molded articles which are produced by the process according to one of claims 1 to 14.

23. Bed pads which contain cellulosic molded articles which are produced by the process according to one of claims 1 to 14.

24. Filter materials and / or filters containing cellulosic shaped bodies which are produced by the method according to one of claims 1 to 14.

25. Packaging materials, in particular food packaging, which contain cellulosic molded articles which are produced by the process according to one of claims 1 to 14.

26. Cable sheaths containing cellulosic molded articles which are produced by the method according to one of claims 1 to 14.