EP2328626A2

EP2328626A2 - Wound dressing having a polyurethane foam layer and a cover layer made of thermoplastic polymer

Info

Publication number: EP2328626A2
Application number: EP09778394A
Authority: EP
Inventors: Jan SCHÖNBERGER
Original assignee: Bayer MaterialScience AG
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2008-09-19
Filing date: 2009-09-08
Publication date: 2011-06-08
Also published as: AU2009294937A1; JP2012502708A; EP2165718A1; BRPI0919337A2; KR20110060902A; RU2011115101A; WO2010031509A2; WO2010031509A3; CN102159165A; CA2737468A1; TW201023917A; US20110171277A1

Abstract

The present invention relates to a layer composite, suited as a wound dressing, comprising a foam layer (10) and a cover layer (20), wherein the cover layer (20) comprises thermoplastic polymer, preferably polyurethane, and is at least partially directly connected to the foam layer (10), and wherein the foam layer (10) comprises a polyurethane foam which is obtained by foaming and drying a composition comprising an aqueous, anionically hydrophilized polyurethane dispersion (I). The foam can be stabilized using ethylene oxide/propylene oxide block copolymers. The invention further relates to a method for producing a layer composite of said kind and to the use thereof, for example as a wound dressing.

Description

Wound dressing with a polyurethane foam layer and a cover layer of thermoplastic polymer

The present invention relates to a layer composite, suitable as a wound dressing, comprising a foam layer and a cover layer, wherein the cover layer comprises a thermoplastic polymer and is at least partially directly connected to the foam layer. It further relates to a method for producing such a layer composite and its use, for example as a wound dressing.

In the treatment of wounds, wound dressings with a foam layer lying on the wound can be used. This has proven to be advantageous, since on the absorption capacity of the foam for emerging from the wound moisture, a healing beneficial climate in the wound can be achieved. Such foams, however, often have the disadvantage that they can be polluted, colonized by bacteria or destroyed by mechanical stress during wear.

As a solution, wound dressings can be provided on the outside with a protective cover foil. This cover sheet can provide germ proof, seal against exudate exiting the wound while permitting water vapor permeability of the wound dressing. So far, the cover sheet must be connected by means of an adhesive with the foam layer.

The use of an adhesive, however, has disadvantages. The application of an adhesive layer means additional labor and material costs and thus additional costs in the production of a wound dressing. Furthermore, the adhesive may adversely affect the permeability to water vapor. Finally, the adhesive can also influence the thermal deformability of the wound dressing.

WO 2007/115696, to which reference is made in its entirety, discloses a process for the preparation of polyurethane foams for wound treatment in which a composition containing a polyurethane dispersion and specific coagulants is foamed and dried. The polyurethane dispersions can be obtained, for example, by reacting isocyanate-functional prepolymers of organic polyisocyanates and polymeric polyols having number average molecular weights of from 400 g / mol to 8000 g / mol and OH functionalities of from 1.5 to 6 and optionally with hydroxy-functional compounds having molecular weights of 62 g / mol to 399 g / mol and, if appropriate, isocyanate-reactive, anionic or potentially anionic and optionally nonionic hydrophilicizing agents. The free NCO groups of the prepolymer are then wholly or partially optionally with amino-functional compounds having molecular weights of 32 g / mol to 400 g / mol and reacted with arninofunktionellen, anionic or potentially anionic hydrophilicizing agents with chain extension. The prepolymers are dispersed in water before, during or after this step. Optionally contained potentially ionic groups are converted by partial or complete reaction with a neutralizing agent in the ionic form.

EP 0 485 657 discloses a dressing for wounds or skin ulcers. The overlay includes a semi-permeable polyurethane film and a plurality of concentric polyethylene foam rings. The application of the foam rings to a semipermeable thin film allows the influence on the moisture / vapor permeability properties of the wound dressing. These can be tailored to the wound environment. The semipermeable thin film is bonded to the upper surface of a ring. It is further disclosed that this connection is achieved by means of an adhesive.

DE 103 01 835 discloses a plaster with a printed wound dressing and a transparent fixing film. The wound dressing can be individually printed and molded in particular taking into account the contours of imprinted motifs. The one-sided adhesive on the wound-facing side fixing film overlaps the wound dressing at least on two sides and is made of transparent material, whereby the cosmetic impairment is reduced by the plaster substantially to the size of the wound dressing. The protruding adhesive transparent fixation foil provides a good hold, with additional segmentation even in problematic skin regions. Also disclosed are a method of making this patch, its application, and methods of use. The transparent fixing foil may consist of polyurethane. According to the teaching of this publication, the transparent fixing film material is provided on the wound-facing side with a transparent adhesive, which on the one hand ensures the fixation of the plaster on the skin and on the other hand for the fixation of the wound dressing on the fixing film.

There is thus a need for alternative wound dressings. In particular, there is a need for wound dressings in which a foam layer and a cover layer without adhesive are bonded together in a non-limiting strength and which can be thermally deformed.

The invention therefore proposes a layer composite, suitable as a wound dressing, comprising a foam layer and a cover layer, wherein the cover layer comprises a thermoplastic polymer and is at least partially directly connected to the foam layer and wherein the foam layer comprises a polyurethane foam obtained by comprising a composition an aqueous, anionically hydrophilicized polyurethane dispersion (I) is foamed and dried. It is envisaged that the foam layer comprises a foam which is obtainable from a foamed polyurethane dispersion. This foam layer is applied to the wound to be covered. Advantageously, this foam has a microporous, at least partially open-pore structure with cells communicating with each other.

The cover layer of the layer composite according to the invention comprises a thermoplastic polymer. By this is meant first a polymer which, when repeatedly heated and cooled in the temperature range typical of the material for processing and application, remains thermoplastic. By thermoplastic is meant the property of a plastic to soften in a typical temperature range for him repeatedly in the heat and harden on cooling and be repeatedly formed in the softened state by flow, for example as a molded part, extrudate or forming part to semifinished or articles. Advantageously, the cover layer is embodied as a semipermeable membrane, that is to say as a membrane which retains liquid exiting from the wound through the foam layer and water from the outside, but allows water vapor to pass through.

It has also proven to be particularly advantageous if their thicknesses are adjusted in the membranes or films so that these in a range of> 5 microns to <80 microns, in particular from> 5 microns to <60 microns and most preferably from> 10 microns to ≤30 microns and they have an elongation at break of over 450%.

In the context of the present invention, the cover layer and the foam layer are at least partially directly connected to one another. This means that there are areas in the layer composite in which the two layers lie directly on top of each other. In these areas, the layer composite is characterized precisely by the fact that no adhesive between the foam layer and the cover layer is present.

The polyurethane dispersion (I) comprises polyurethanes, free isocyanate groups being at least partially reacted with anionic or potentially anionic hydrophilicizing agents. Such hydrophilizing agents are compounds which have isocyanate-reactive functional groups such as amino, hydroxy or thiol groups and furthermore acid or acid anion groups such as carboxylate, sulfonate or phosphonate groups.

The selection of the foam layer and the cover layer according to the invention makes it possible to obtain wound dressings provided with a protective, cover and / or membrane film which can be produced in fewer passes by eliminating the requirement for an adhesive layer. Nevertheless, the adhesion of the layers to each other is sufficient. The layered composites can also be further processed after their production by means of thermal deformation, so that a wide variety of forms for the wound dressings can be achieved. In one embodiment of the layer composite according to the invention, the composition from which the polyurethane foam of the foam layer is obtained further comprises additives selected from the group comprising fatty acid amides, sulfosuccinamides, hydrocarbon sulfonates, hydrocarbon hydrosulfates, fatty acid salts, alkylpolyglycosides and / or ethylene oxide / propylene oxide block copolymers.

Such additives may act as foaming agents and / or foam stabilizers. In the fatty acid amides, sulfosuccinamides, hydrocarbon sulfonates, hydrocarbon sulfates or fatty acid salts, the lipophilic group preferably contains> 12 to <24 carbon atoms. Suitable alkyl polyglycosides are obtainable, for example, by reacting relatively long-chain monoalcohols (> 4 to <22 C atoms in the alkyl radical) with mono-, di- or polysaccharides. Also suitable are alkyl benzene sulfonates or alkyl benzene sulfates having> 14 to <24 carbon atoms in the hydrocarbon radical.

The fatty acid amides are preferably those based on mono- or di (C ₂ / C ₃ alkanol) amines. The fatty acid salts may be, for example, alkali metal salts, amine salts or unsubstituted ammonium salts.

Such fatty acid derivatives are typically based on fatty acids such as lauric, myristic, palmitic, oleic, stearic, ricinoleic, behenic or arachidic, coconut, tallow, soybean and their hydrogenation products.

Exemplary foam stabilizers are mixtures of sulfosuccinamides and ammonium stearates, these preferably being> 20% by weight to <60% by weight, more preferably> 30% by weight to <50% by weight of ammonium stearates and preferably> 40% by weight, to < 80% by weight, more preferably> 50% by weight to <70% by weight of sulfosuccinamides.

Further foam stabilizers which can be used by way of example are mixtures of fatty alcohol polyglycosides and ammonium stearates, these preferably being> 20% by weight to <60% by weight, particularly preferably> 30% by weight to <50% by weight of ammonium stearates and preferably> 40% by weight % to <80% by weight, more preferably> 50% by weight to <70% by weight of fatty alcohol polyglycosides.

The ethylene oxide / propylene oxide block copolymers are addition products of ethylene oxide and propylene oxide with OH- or NH-functional starter molecules.

Suitable starter molecules in principle include water, polyethylene glycols, polypropylene glycols, glycerol, trimethylolpropane, pentaerythritol, ethylenediamine, tolylenediamine, sorbitol, sucrose and mixtures thereof. Preference is given to using di- or trifunctional compounds of the abovementioned type as initiators. Particularly preferred are polyethylene glycol or polypropylene glycol.

By the respective amount of alkylene oxide and the number of ethylene oxide (EO) - and propylene oxide (PO) blocks block copolymers of different types can be obtained.

In principle, it is also possible that the copolymers which are strictly block-wise composed of ethylene oxide or propylene oxide also have individual mixed blocks of EO and PO.

Such mixed blocks are obtained when mixtures of EO and PO are used in the polyaddition reaction, so that with respect to this block results in a statistical distribution of EO and PO in this block.

The EO / PO block copolymers used according to the invention preferably have contents of ethylene oxide units of> 5% by weight, particularly preferably> 20% by weight and very particularly preferably> 40% by weight, based on the sum of the ethylene oxide and propylene oxide units present in the copolymer.

The EO / PO block copolymers used according to the invention preferably have ethylene oxide unit contents of <95% by weight, more preferably <90% by weight and most preferably <85% by weight, based on the sum of the ethylene oxide and propylene oxide units present in the copolymer on.

Preferably, the EO / PO block copolymers used according to the invention have number-average molecular weights of ≥ 1000 g / mol, more preferably> 2000 g / mol, very particularly preferably> 5000 g / mol.

The EO / PO block copolymers used according to the invention preferably have number-average molecular weights of <10000 g / mol, more preferably <9500 g / mol, very particularly preferably <9000 g / mol.

An advantage of the use of the EO / PO block copolymers is that the foam obtained has a lower hydrophobicity than when using other stabilizers. As a result, the absorption behavior for liquids can be favorably influenced. In addition, unlike other stabilizers, non-cytotoxic foams are obtained using the EO / PO block copolymers.

It is preferable that the ethylene oxide / propylene oxide block copolymers have a structure according to the general formula (1): HO (CH ₂ CH ₂ O) _n - (CH ₂₂ CCHHOO) ₀₁ - (CH ₂ CH ₂ O) _n H CH ₃

(1)

wherein the value of n is in a range of ≥ 2 to <200, and the value of m is in a range of> 10 to <60.

The value of n is preferably in a range from> 60 to <180, more preferably from> 130 to <160. The value of m is preferably in a range from> 25 to <45, more preferably from> 25 to <35.

Particularly preferred are EO / PO block copolymers of the aforementioned type, these having a hydrophilic-lipophilic-balance (HLB) value of> 4, more preferably of> 8 and most preferably of> 14. The HLB value is calculated according to the formula HLB = 20 ^• Mh / M where Mh is the number average molecular weight of the hydrophilic formed from ethylene oxide portion of the molecule and M is the number average molecular weight of the total molecule (Griffin, WC: Classification of Surface Active Agents by HLB, J. Soc., Cosmet., Chem., 1, 1949). However, the HLB value is ≦ 19, preferably <18.

In one embodiment of the layer composite of the invention, the aqueous, anionically hydrophilic polyurethane dispersion (I) can be obtained by

A) isocyanate-functional prepolymers obtainable from a reaction mixture comprising

Al) organic polyisocyanates and

A2) polymeric polyols having number average molecular weights of> 400 g / mol to <

8000 g / mol and OH functionalities of> 1.5 to <6

and subsequently

B) the free NCO groups of the prepolymers wholly or partly with

Bl) amino-functional, anionic or potentially anionic hydrophilicizing agents

are reacted under chain extension and the prepolymers are dispersed in water before, during or after step B), wherein further present in the reaction mixture potentially ionic groups by partial or complete reaction with a neutralizing agent in the ionic form is converted.

Preferred aqueous anionic polyurethane dispersions (I) have a low level of hydrophilic anionic groups, preferably from ≥ 0.1 to <15 milliequivalents per 100 g of solid resin.

In order to achieve a good sedimentation stability, the number-average particle size of the specific polyurethane dispersions is preferably <750 nm, particularly preferably <500 nm, determined by means of laser correlation spectroscopy.

The ratio of NCO groups of the compounds of component Al) to NCO-reactive groups such as amino, hydroxy or thiol groups of the compounds of components A2) to A4) is in the preparation of the NCO-functional prepolymer> l, 05 to <3 , 5, preferably> 1, 2 to <3.0, more preferably> 1.3 to <2.5.

The amino-functional compounds in step B) are used in such an amount that the equivalent ratio of isocyanate-reactive amino groups of these compounds to the free isocyanate groups of the prepolymer> 40% to <150%, preferably between> 50% and <125%, more preferably between ≥ 60% and <120%.

Suitable polyisocyanates of component Al) are aromatic, araliphatic, aliphatic or cycloaliphatic polyisocyanates having an NCO functionality of> 2.

Examples of such suitable polyisocyanates are 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone isocyanate (IPDI), 2,2,4- and / or 2,4,4-trimethylhexamethylene diisocyanate, the isomeric bis ( 4,4'-isocyanatocyclohexyl) methanes or mixtures thereof of any isomer content, 1,4-cyclohexylene diisocyanate, 1,4-phenylene diisocyanate, 2,4- and / or 2,6-toluene diisocyanate (TDI), 1,5-naphthylene diisocyanate, 2, 2'- and / or 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,3- and / or 1,4-bis- (2-isocyanato-prop-2-yl) benzene (TMXDI), 1,3-bis (isocyanatomethyl) benzene (XDI), and alkyl 2,6-diisocyanatohexanoate (lysine isocyanates) with C 1 to Cg alkyl groups.

In addition to the abovementioned polyisocyanates, it is also possible proportionally to use modified diisocyanates having a uretdione, isocyanurate, urethane, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure and unmodified polyisocyanate having more than 2 NCO groups per molecule such as 4 Isocyanatomethyl-l, 8-octane diisocyanate (nonane triisocyanate) or triphenylmethane 4,4 ', 4 "triisocyanate with.

Preference is given to polyisocyanates or polyisocyanate mixtures of the abovementioned type with exclusively aliphatic and / or cycloaliphatic bound Isocyanate groups and an average NCO functionality of the mixture of ≥2 to <4, preferably ≥2 to <2.6 and particularly preferably ≥2 to <2.4.

Particular preference is given in Al) to using 1,6-hexamethylene diisocyanate, isophorone diisocyanate, the isomeric bis (4,4'-isocyanatocyclohexyl) methanes and mixtures thereof.

In A2) are polymeric polyols having a number average molecular weight Mn of> 400 g / mol to <8000 g / mol, preferably from> 400 g / mol to <6000 g / mol and particularly preferably from> 600 g / mol to <3000 g / mol used. These preferably have an OH functionality of> 1.5 to <6, particularly preferably from> 1.8 to <3, very particularly preferably from> 1.9 to <2.1.

Such polymeric polyols are, for example, polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester polyacrylate polyols, polyurethane polyacrylate polyols, polyurethane polyester polyols, polyurethane polyether polyols, polyurethane polycarbonate polyols and polyester polycarbonate polyols. These can be used in A2) individually or in any mixtures with each other.

Such polyester polyols are polycondensates of di- and optionally tri- and tetraols and di- and optionally tri- and tetracarboxylic acids or hydroxycarboxylic acids or lactones. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols for the preparation of the polyesters.

Examples of suitable diols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, furthermore 1,2-propanediol, 1,3-

Propandiol, butanediol (l, 3), butanediol (l, 4), hexanediol (l, 6) and isomers, neopentyl glycol or

Hydroxypivalic acid neopentyl glycol esters, with hexanediol (1,6) and isomers, neopentyl glycol and neopentyl glycol hydroxypivalate being preferred. In addition, polyols can also be used

Trimethylolpropane, glycerol, erythritol, pentaerythritol, Triemthylolbenzol or trishydroxyethyl isocyanurate be used.

Suitable dicarboxylic acids are phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid and / or 2 , 2-Dimethylsuccinic be used. The acid source used may also be the corresponding anhydrides.

If the average functionality of the polyol to be esterified is> 2, monocarboxylic acids such as benzoic acid and hexanecarboxylic acid may additionally be used. _

Preferred acids are aliphatic or aromatic acids of the abovementioned type. Particular preference is given to adipic acid, isophthalic acid and, if appropriate, trimellitic acid.

Hydroxycarboxylic acids which can be used as reaction additives in the preparation of a hydroxyl-terminated polyester polyol include hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid, hydroxystearic acid and the like. Suitable lactones are caprolactone, butyrolactone and homologs. Preference is given to caprolactone.

It is likewise possible in A2) to use hydroxyl-containing polycarbonates, preferably polycarbonatediols, having number-average molecular weights Mn of> 400 g / mol to <8000 g / mol, preferably ≥600 g / mol to <3000 g / mol. These are obtainable by reaction of carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate or phosgene with polyols, preferably diols.

Examples of such diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bis-hydroxymethylcyclohexane, 2- Methyl-l, 3-propanediol, 2,2,4-Trimethylpentandiol-l, 3, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A and lactone-modified diols of the aforementioned kind.

The polycarbonate diol preferably contains> 40% by weight to <100% by weight of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives. Such hexanediol derivatives are based on hexanediol and have terminal OH groups as well as ester or ether groups. Such derivatives are obtainable by reaction of hexanediol with excess caprolactone or by etherification of hexanediol with itself to di- or trihexylenglykol.

Instead of or in addition to pure polycarbonate diols, it is also possible to use polyether-polycarbonate diols in A2).

The hydroxyl-containing polycarbonates are preferably built linear.

Likewise, in A2) polyether polyols can be used.

Suitable examples are polytetramethylene glycol polyethers, as obtainable by polymerization of tetrahydrofuran by means of cationic ring opening.

Also suitable polyether polyols are the addition products of styrene oxide, ethylene oxide,

Propylene oxide, butylene oxide and / or epichlorohydrin to di- or polyfunctional starter molecules. Polyether polyols, based on the at least proportional addition of ethylene oxide to di- or polyfunctional starter molecules, can also be used as component A4) (nonionic hydrophilicizing agents).

Examples of suitable starter molecules which can be used are water, butyldiglycol, glycerol, diethylene glycol, trimethylolpropane, propylene glycol, sorbitol, ethylenediamine, triethanolamine or 1,4-butanediol. Preferred starter molecules are water, ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol and butyl diglycol.

Particularly preferred embodiments of the polyurethane dispersions (I) comprise, as component A2), a mixture of polycarbonate polyols and polytetramethylene glycol polyols, in which mixture the proportion of polycarbonate polyols in the mixture is from> 20% by weight to <80% by weight and the proportion of polytetramethylene glycol polyols> 20% by weight to <80% by weight. Preference is given to a proportion of> 30% by weight to <75% by weight of polytetra-methylene glycol polyols and a proportion of> 25% by weight to <70% by weight of polycarbonate polyols. Particularly preferred is a proportion of> 35% by weight to <70% by weight of polytetramethylene glycol polyols and a fraction of> 30% by weight to <65% by weight of polycarbonate polyols, in each case with the proviso that the sum of the weight percent of Polycarbonatepolyols and polytetramethylene glycol polyols <100% by weight and the proportion of the sum of the polycarbonate polyols and polytetramethylene glycol polyetherpolyols in the component A2) is> 50% by weight, preferably> 60% by weight and particularly preferably> 70% by weight.

Isocyanate-reactive anionic or potentially anionic hydrophilicizing agents of component B1) are understood as meaning all compounds which have at least one isocyanate-reactive group, such as an amino, hydroxy or thiol group, and at least one

For example, functionality such as -COOTVI ⁺ , -SO ₃ TvI ⁺ , -PO (OTvT) ₂ with M ⁺ is the same

Metal cation, H ⁺ , NH ₄ ⁺ , NHR ₃ ⁺ , wherein each R may be a C _r C, ₂ alkyl, C ₅ -C ₆ cycloalkyl and / or a C ₂ -C ₄ hydroxyalkyl which, when interacting with aqueous media enters a pH-dependent dissociation equilibrium and can be charged in this way negative or neutral.

Preferably, the isocyanate-reactive anionic or potentially anionic hydrophilicizing agents are isocyanate-reactive amino-functional anionic or potentially anionic hydrophilicizing agents.

Suitable anionic or potentially anionic hydrophilizing compounds are mono- and diaminocarboxylic acids, mono- and diaminosulfonic acids and mono- and diaminophosphonic acids and their salts. Examples of such anionic or potentially anionic hydrophilicizing agents are N- (2-aminoethyl) -β-alanine, 2- (2-aminoethylamino) -ethanesulfonic acid, ethylenediamine-propyl- or -butylsulfonic acid, 1,2- or 1,3-propylenediamine -j3-ethylsulfonic acid, glycine, alanine, Taurine, lysine, 3,5-diaminobenzoic acid and the addition product of IPDA and acrylic acid (EP-A 0 916 647, Example 1). Furthermore, cyclohexylaminopropanesulfonic acid (CAPS) from WO-A 01/88006 can be used as anionic or potentially anionic hydrophilicizing agent.

Preferred anionic or potentially anionic hydrophilicizing agents of component B1) are those of the abovementioned type which have carboxylate or caroboic acid groups and / or sulfonate groups, such as the salts of N- (2-aminoethyl) -β-alanine, the (2-aminoethylamino) ethanesulfonic acid or the addition product of IPDA and acrylic acid (EP-A 0 916 647, Example 1).

For hydrophilization it is also possible to use mixtures of anionic or potentially anionic hydrophilicizing agents and nonionic hydrophilicizing agents.

In a further embodiment of the layer composite according to the invention, the reaction mixture in step A) furthermore comprises:

A3) hydroxy-functional compounds with molecular weights of> 62 g / mol to <399 g / mol

The compounds of component A3) have molecular weights of> 62 g / mol to <399 g / mol.

In A3) it is possible to use polyols of the stated molecular weight range having up to 20 carbon atoms, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butylene glycol, cyclohexanediol, 1,4 Cyclohexanedimethanol, 1,6-hexanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, bisphenol A (2,2-bis (4-hydroxyphenyl) propane), hydrogenated bisphenol A, (2,2-bis (4-hydroxycyclohexyl) propane), trimethylolpropane, Glycerol, pentaerythritol and any mixtures thereof are used with each other.

Also suitable are ester diols of the stated molecular weight range, such as α-hydroxybutyl-e-hydroxycaproic acid ester, ω-hydroxyhexyl-γ-hydroxybutyric acid ester, adipic acid (ω-hydroxyethyl) ester or terephthalic acid bis (ω-hydroxyethyl) ester.

Furthermore, it is also possible to use monofunctional, isocyanate-reactive, hydroxyl group-containing compounds in A3). Examples of such monofunctional compounds are ethanol, n-butanol, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether. ether, 2-ethylhexanol, 1-octanol, 1-dodecanol, 1-hexadecanol.

Preferred compounds of component A3) are 1,6-hexanediol, 1,4-butanediol, neopentyl glycol and trimethylolpropane.

A4) isocyanate-reactive, anionic or potentially anionic and optionally nonionic hydrophilicizing agents

Under anionic or potentially anionic hydrophilizing compounds of component A4) are understood to mean all compounds which have at least one isocyanate-reactive group such as an amino, hydroxyl or thiol group and at least one functionality such as -COOTvI ⁺ , -SO ₃ TVI ⁺ , -PO (O ^"M ⁺⁾ ₂ where M ^{+ is} for example a metal cation, H ^+, NH ₄ ^+, NHR ₃ ^+, wherein each R is a Ci-Ci ₂ -alkyl, C ₅ -C ₆ - cycloalkyl radical and / or a C ₂ - C ₄ -Hydroxyalkyl may be, which undergoes a pH-dependent dissociation equilibrium when interacting with aqueous media and may be charged in this way negative or neutral .. Suitable anionic or potentially anionic hydrophilic compounds are, for example mono- and dihydroxycarboxylic, mono- and Dihydroxysulfonic acids and mono- and dihydroxyphosphonic acids and their salts Examples of such anionic or potentially anionic hydrophilicizing agents l are dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, malic acid, citric acid, glycolic acid, lactic acid and the propoxylated adduct of 2-butenediol and NaHSO ₃ , as described in DE-A 2 446 440, page 5-9, formula I-III. Preferred anionic or potentially anionic hydrophilicizing agents of component A4) are those of the abovementioned type which have carboxylate or carboxylic acid groups and / or sulfonate groups.

Particularly preferred anionic or potentially anionic hydrophilicizing agents are those which contain carboxylate or carboxylic acid groups as ionic or potentially ionic groups, such as dimethylolpropionic acid, dimethylolbutyric acid and hydroxypivalic acid and / or salts thereof.

Suitable nonionically hydrophilicizing compounds of component A4) are, for example, polyoxyalkylene ethers containing at least one hydroxy or amino group, preferably at least one hydroxy group. Examples of these are the monohydroxy-functional, on average> 5 to <70, preferably> 7 to <55 ethylene oxide units per molecule having Polyalkylenoxidpolyetheralkohole as are accessible by alkoxylation of suitable starter molecules. These are either pure polyethylene oxide ethers or mixed polyalkylene oxide ethers, , ,

wherein they contain> 30 mol%, preferably> 40 mol% based on all contained alkylene oxide units of ethylene oxide units.

Preferred polyethylene oxide ethers of the abovementioned type are monofunctional mixed polyalkylene oxide polyethers which have> 40 mol% to <100 mol% of ethylene oxide and> 0 mol% to <60 mol% of propylene oxide units.

Preferred nonionically hydrophilicizing compounds of component A4) are those of the abovementioned type, which are block (co) polymers which are prepared by blockwise addition of alkylene oxides to suitable initiators.

Suitable starter molecules for such nonionic hydrophilicizing agents are saturated monoalcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, n-decanol, n-dodecanol, n-butanol. Tetradecanol, n-hexadecanol, n-octadecanol, cyclohexanol, the isomeric methylcyclohexanols or hydroxymethylcyclohexane, 3-ethyl-3-hydroxymethyloxetane or tetrahydrofurfuryl alcohol, diethylene glycol monoalkyl ethers such as diethylene glycol monobutyl ether, unsaturated alcohols such as allyl alcohol, 1,1-dimethylallyl alcohol or oleic alcohol, aromatic alcohols such as Phenol, the isomeric cresols or methoxyphenols, araliphatic alcohols such as benzyl alcohol, anisalcohol or cinnamyl alcohol, secondary monoamines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, bis (2-ethylhexyl) amine, N-methyl- and N-ethylcyclohexylamine or dicyclohexylamine and heterocyclic secondary amines such as Morp holin, pyrrolidine, piperidine or 1H-pyrazole. Preferred starter molecules are saturated monoalcohols of the abovementioned type. Particular preference is given to using diethylene glycol monobutyl ether or n-butanol as starter molecules.

Alkylene oxides which are suitable for the alkoxylation reaction are, in particular, ethylene oxide and propylene oxide, which can be used in any desired order or even as a mixture in the alkoxylation reaction.

In a further embodiment of the layer composite according to the invention, the free NCO groups of the prepolymers are further reacted completely or partially in step B)

B2) amino-functional compounds with molecular weights of> 32 g / mol to <400 g / mol

As component B2) can di- or polyamines such as 1, 2-ethylenediamine, 1,2- and 1,3-diamino propane, 1, 4-diaminobutane, 1,6-diaminohexane, isophoronediamine, isomer mixtures of 2,2,4 - and 2,4,4-trimethylhexamethylenediamine, 2-methyl pentamethylene diamine, diethylene triamine, triaminononane, 1,3- and 1,4-xylylenediamine, α, α _(α ', ^{α-tetramethyl-l} l, 3- and -1.4 -xylylenediamine and 4,4-diaminodicyclohexylmethane and / or dimethylethylenediamine. Also possible, but less preferred, is the use of hydrazine as well as hydrazides such as adipic dihydrazide.

In addition, as component B2), compounds which, in addition to a primary amino group, also have secondary amino groups or in addition to an amino group (primary or secondary) also OH groups, can be used. Examples of these are primary / secondary amines, such as diethanolamine, 3-amino-1-methylaminopropane, 3-amino-1-ethylaminopropane, 3-amino-1-cyclohexylaminopropane, 3-amino-1-methylaminobutane, alkanolamines such as N-aminoethylethanolamine , Ethanolamine, 3-aminopropanol, neopentanolamine.

Further, as component B2) also monofunctional isocyanate-reactive amine compounds are used, such as methylamine, ethylamine, propylamine, butylamine, octylamine, laurylamine, stearylamine, isononyloxypropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, N-methylaminopropylamine, diethyl (methyl) aminopropylamine, morpholine , Piperidine or suitable substituted derivatives thereof, amide amines of diprimary amines and monocarboxylic acids, monoketime of diprimary amines, primary / tertiary amines, such as N, N-dimethylaminopropylamine. Preferred compounds of component B2) are 1,2-ethylenediamine, 1, 4-diaminobutane and isophoronediamine.

In a further embodiment of the layer composite of the invention, in the preparation of the aqueous, anionically hydrophilicized polyurethane dispersions (I), the component Al) is selected from the group comprising 1,6-hexamethylene diisocyanate, isophorone diisocyanate and / or the isomeric bis (4, 4'-isocyanatocyclohexyl) methane. Furthermore, component A2) comprises a mixture of polycarbonate polyols and polytetramethylene glycol polyols, the proportion of the sum of the polycarbonate polyols and the polytetramethylene glycol polyether polyols on component A2) being> 70% by weight to <100% by weight.

In addition to the polyurethane dispersions (I) and the additives, other auxiliaries can also be used.

Examples of such auxiliaries are thickeners or thixotropic agents, antioxidants, light stabilizers, emulsifiers, plasticizers, pigments, fillers and / or leveling agents.

Commercially available thickeners can be used as thickeners, such as dextrin, starch or cellulose derivatives such as cellulose ethers or hydroxyethylcellulose, polysaccharide derivatives such as gum arabic or guar, organic fully synthetic thickeners based on polyacrylic acids, polyvinylpyrrolidones, poly (meth) acrylic compounds or polyurethanes (associative thickeners) and inorganic thickeners such as bentonites or silicic acids. In principle, the compositions according to the invention may also contain crosslinkers such as unblocked polyisocyanates, amide and amine-formaldehyde resins, phenolic resins, aldehyde and ketone resins such as, for example, phenol-formaldehyde resins, resols, furan resins, urea quartz, carbamic acid ester resins, triazine resins, melamine resins, benzoguanamine resins, cyanamide resins or aniline resins ,

In a further embodiment of the novel layer composite, the thermoplastic polymer of the cover layer comprises materials selected from the group consisting of polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethers, polyesters, polyamide, polycarbonate, polyether-polyamide copolymers, polyacrylate, polymeth- acrylate and / or polymaleate. This is preferably thermoplastic polyurethane (TPU). Advantageously, these materials are elastomeric. Also advantageous are films of such materials, which have a thickness of> 5 microns to <80 microns, in particular from> 5 microns to <60 microns and most preferably from> 10 microns to <30 microns.

In a further embodiment of the inventive layer composite, the thermoplastic polymer of the cover layer comprises polyurethanes which are selected from the group comprising aliphatic polyester polyurethanes, aromatic polyester polyurethanes, aliphatic polyether polyurethanes and / or aromatic polyether polyurethanes. Thus, breathable elastic membrane films can be obtained. The cover shells thus obtained are characterized by high flexibility / elasticity over a wide temperature range, good wind and water resistance with high water vapor permeability, low noise, good textile feel, washing and cleaning resistance, very good chemical and mechanical resistance and freedom from plasticizers.

In a further embodiment of the layer composite according to the invention, the direct connection between the foam layer and the cover layer has a peel strength of> 0.01 N / mm to <0.50 N / mm. The peel strength may also range from> 0.03 N / mm to <0.30 N / mm or from> 0.05 N / mm to <0.20 N / mm. The peel strength can be determined by performing 360 ° peel tests on a Zwick universal testing machine at a crosshead speed of 100 mm / min.

In a further embodiment of the layer composite according to the invention, the permeability of the layer composite to water vapor is> 1000 g / 24 h × m ² to ≦ 4000 g / 24 h × m ² . This permeability to water vapor can also be in a range from> 1500 g / 24 hxm ² to <3000 g / 24 hxm ² or from> 1800 g / 24 hxm ² to <2500 g / 24 hxm ² .

It is possible that in the erf Schichtenndungsgemäßen layer composite, the cover layer a Tightness to water, expressed as a load on the layer of water column, of> 2000 mm. This value can also be in a range of> 4000 mm or> 6000 mm.

Furthermore, the cover layer can have a permeability to water vapor of> 1000 gl 2A h. ^χ m ² to <8000 g / 24 h * m ² have. This permeability to water vapor may also be in a range from> 2000 g / 24 hxm ² to <6000 g / 24 hxm ² or from> 3000 g / 24 hxm ² to <5000 g / 24 hxm ² .

In an exemplary formulation for the preparation of the polyurethane dispersions, the components A1) to A4) and B1) to B2) are used in the following amounts, the individual amounts always adding up to <100% by weight:

> 5% by weight to <40% by weight of component Al);

> 55% by weight to <90% by weight of component A2);

> 0.5% by weight to <20% by weight of sum of components A3) and B2);

> 0.1% by weight to <25% by weight of the sum of the components A4) and B1), wherein, based on the total amounts of the components A1) to A4) and B1) to B2)> 0.1% by weight to <5 % By weight of anionic or potentially anionic hydrophilicizing agents from A4) and / or Bl).

In a further exemplary formulation for the preparation of the polyurethane dispersions, the components Al) to A4) and Bl) to B2) are used in the following amounts, the individual amounts always adding up to <100% by weight:

> 5% by weight to <35% by weight of component Al);

> 60% by weight to ^ O% by weight of component A2);

> 0.5% by weight to <15% by weight of the sum of components A3) and B2);

> 0.1% by weight to <15% by weight of the sum of the components A4) and B1), wherein based on the total amounts of the components A1) to A4) and B1) to B2)> 0.2% by weight to <4 % By weight of anionic or potentially anionic hydrophilicizing agents from A4) and / or Bl).

In a very particularly preferred formulation for the preparation of the polyurethane dispersions, the components A1) to A4) and B1) to B2) are used in the following amounts, the individual amounts always adding up to <100% by weight: > 10% by weight to <30% by weight of component Al);

Ξ≥65% to <85% by weight of component A2);

> 0.5% by weight to <14% by weight of the sum of components A3) and B2);

> 0.1% by weight to <13.5% by weight of the sum of the components A4) and B1), wherein based on the total amounts of the components A1) to A4) and B1) to B2)> 0.5% by weight to <3.0% by weight of anionic or potentially anionic hydrophilicizing agents from A4) and / or Bl) are used.

The preparation of the anionically hydrophilicized polyurethane dispersions (T) can be carried out in one or more stages in homogeneous or multistage reaction, in some cases in disperse phase. After complete or partial polyaddition from Al) to A4), a dispersing, emulsifying or dissolving step takes place. This is followed, if appropriate, by a further polyaddition or modification in disperse phase.

In this case, methods such as prepolymer mixing method, acetone method or melt dispersion method can be used. Preferably, the acetone method is used.

For the preparation by the acetone process, the constituents A2) to A4) and the polyisocyanate component Al) are initially introduced in whole or in part to prepare an isocyanate-functional polyurethane prepolymer and optionally diluted with a water-miscible but isocyanate-inert solvent and cooled to temperatures in the Range of> 50 ⁰ C to <120 ⁰ C heated. To accelerate the isocyanate addition reaction, the catalysts known in polyurethane chemistry can be used.

Suitable solvents are the customary aliphatic, ketofunctional solvents, such as acetone or 2-butanone, which can be added later not only at the beginning of the preparation but also, if appropriate, in some cases. Preference is given to acetone and 2-butanone.

Other solvents such as xylene, toluene, cyclohexane, butyl acetate, methoxypropyl acetate, N-methylpyrrolidone, N-ethylpyrrolidone, solvents with ether or ester units can additionally be used and distilled off in whole or in part or completely in the case of N-methylpyrrolidone, N -Ethylpyrrolidone remain in the dispersion. However, apart from the usual aliphatic, ketofunctional solvents, no other solvents are preferably used.

Subsequently, the constituents of Al) to A4), which are optionally not added at the beginning of the reaction, are metered in.

In the preparation of the polyurethane prepolymer from Al) to A4), the molar mass Ratio of isocyanate groups to isocyanate-reactive groups, for example> 1, 05 to <3, 5, preferably> 1, 2 to <3.0 and particularly preferably> 1, 3 to <2.5.

The reaction of the components Al) to A4) to the prepolymer takes place partially or completely, but preferably completely. Thus, polyurethane prepolymers containing free isocyanate groups are obtained in bulk or in solution.

In the neutralization step for the partial or complete conversion of potentially anionic groups into anionic groups, bases such as tertiary amines, for example trialkylamines having> 1 to <12, preferably> 1 to <6 C atoms, more preferably ≥2 to <3 C atoms in any alkyl radical or alkali metal bases such as the corresponding hydroxides used.

Examples of these are trimethylamine, triethylamine, methyldiethylamine, tripropylamine, N-methylmorpholine, methyldiisopropylamine, ethyldiisopropylamine and diisopropylethylamine. The alkyl radicals may, for example, also carry hydroxyl groups, as in the case of the dialkylmonoalkanol, alkyldialkanol and trialkanolamines. If appropriate, inorganic bases such as aqueous ammonia solution or sodium or potassium hydroxide can also be used as neutralizing agents.

Preference is given to ammonia, triethylamine, triethanolamine, dimethylethanolamine or diisopropylethylamine and also sodium hydroxide and potassium hydroxide, particular preference to sodium hydroxide and potassium hydroxide.

The molar amount of the bases is between> 50 mol% and <125 mol%, preferably between> 70 mol% and <100 mol% of the molar amount of the acid groups to be neutralized. The neutralization can also take place simultaneously with the dispersion in that the dispersing water already contains the neutralizing agent.

Subsequently, in a further process step, if not yet done or only partially done, the resulting prepolymer with the aid of aliphatic ketones such as acetone or 2-butanone.

In the chain extension in step B) NH ₂ - and / or NH-functional components are partially or completely reacted with the remaining isocyanate groups of the prepolymer. The chain extension is preferably carried out in water before dispersion.

For chain termination usually amines B2) with an isocyanate-reactive group such as methylamine, ethylamine, propylamine, butylamine, octylamine, laurylamine,

Stearylamine, isononyloxypropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine,

N-methylaminopropylamine, diethyl (methyl) aminopropylamine, morpholine, piperidine, or suitable nete substituted derivatives thereof, amide amines from diprimary amines and monocarboxylic acids, monoketime of diprimary amines, primary / tertiary amines, such as N, N-dimethylaminopropylamine used.

When partial or complete chain extension is anionic or potentially anionic hydrophilizing agents according to the definition Bl) with NH ₂ - or NH groups, the chain extension of the prepolymers is preferably carried out before the dispersion.

The aminic components B1) and B2) can optionally be used individually or in mixtures in water or solvent-diluted form in the process according to the invention, wherein in principle any order of addition is possible.

When water or organic solvents are used as diluents, the diluent content in the chain-extending component used in B) is preferably> 70% by weight to <95% by weight.

The dispersion preferably takes place after the chain extension. To this end, the dissolved and chain-extended polyurethane polymer is optionally either added to the dispersing water with high shear, such as vigorous stirring, or, conversely, the dispersing water is stirred into the chain-extended polyurethane polymer solutions. Preferably, the water is added to the dissolved chain-extended polyurethane polymer.

The solvent still present in the dispersions after the dispersion step is then usually removed by distillation. A removal already during the dispersion is also possible.

The residual content of organic solvents in the polyurethane dispersions (I) is typically <1, 0 wt .-%, preferably <0.5 wt .-%, based on the total dispersion.

The pH of the polyurethane dispersions (I) according to the invention is typically ≦ 9.0, preferably <8.5, more preferably less than <8.0, and very particularly preferably> 6.0 to <7.5.

The solids content of the polyurethane dispersions (I) is preferably> 40% by weight to <70% by weight, particularly preferably> 50% by weight to <65% by weight, very particularly preferably> 55% by weight to <65% by weight. % and in particular> 60% by weight to <65% by weight.

Examples of erfϊndungsgemäße compositions are listed below, wherein the sum of the data in weight% assumes a value of <100% by weight. These Compositions comprise, based on the dry substance, typically> 80 parts by weight to <99.5 parts by weight of dispersion (I),> 0 parts by weight to <10 parts by weight of foaming aid,> 0 parts by weight to <10 parts by weight of crosslinker and> 0 parts by weight to <10 parts by weight of thickener ,

Preferably, these compositions according to the invention comprise, based on the dry substance,> 85 parts by weight to <97 parts by weight of dispersion (I),> 0.5 parts by weight to <7 parts by weight of foaming aid,> 0 parts by weight to <5 parts by weight of crosslinking agent and> 0 parts by weight to <5 Parts by weight thickener.

With particular preference these compositions according to the invention, based on the dry substance, comprise> 89 parts by weight to <97 parts by weight of dispersion (I),> 0.5 part by weight to <6 parts by weight of foaming aid,> 0 parts by weight to ≦ A parts by cross-linker and> 0 parts by weight to ≦ A parts by weight thickener.

Examples of inventive compositions comprising ethylene oxide / propylene oxide block copolymers as foam stabilizers are listed below. These compositions comprise, based on dry substance,> 80 parts by weight to <99.9 parts by weight of dispersion (I) and> 0.1 part by weight to <20 parts by weight of the ethylene oxide / propylene oxide block copolymers. Preferably, the compositions comprise, based on dry matter, from> 85 parts by weight to <99.5 parts by weight of dispersion (I) and from 0.5 to 15 parts by weight of the ethylene oxide / propylene oxide block copolymers. Particularly preferred are> 90 parts by weight to <99 parts by weight of dispersion (I) and> 1 part by weight to <10 parts by weight of ethylene oxide / propylene oxide block copolymers and very particularly preferably> 94 parts by weight to <99 parts by weight of dispersion (I) and> 1 to <6 parts by weight of the ethylene oxide / propylene oxide block copolymers.

For the purposes of the present invention, the term "parts by weight" means a relative proportion, but not in the sense of indicating% by weight. Consequently, the numerical sum of the weight fractions can also assume values over 100.

In addition to the components mentioned, it is also possible to use further aqueous binders in the compositions according to the invention. Such aqueous binders may for example be composed of polyester, polyacrylate, polyepoxide or other polyurethane polymers. The combination with radiation-curable binders, as described for example in EP-AO 753 531, is possible. It is also possible to use other anionic or nonionic dispersions, such as polyvinyl acetate, polyethylene, polystyrene, polybutadiene, polyvinyl chloride, polyacrylate and copolymer dispersions. The foaming in the inventive method is done by mechanical stirring of the composition at high speeds, by shaking or by relaxation of a propellant gas.

The mechanical foaming can be carried out with any mechanical stirring, mixing and dispersing techniques. As a rule, this air is entered, but also nitrogen and other gases can be used for this purpose.

The invention furthermore relates to a method for producing a layer composite according to the present invention, comprising the steps:

Providing a foam layer comprising a polyurethane foam obtained by foaming a composition comprising an aqueous, anionically hydrophilicized polyurethane dispersion (I);

Applying a cover layer to the foam layer.

The resulting foam can be applied to a substrate during foaming or immediately thereafter or placed in a mold and dried. Particularly suitable as substrates are papers or films which allow a simple detachment of the wound dressing before it is used to cover an injured area.

The order can be made, for example, by casting or knife coating, but other techniques known per se are possible. A multi-layer application with intermediate drying steps is basically also possible. This can then be followed by the application of the cover layer, followed by drying of the layer composite.

It is alternatively possible that the foam layer is straightened directly onto the cover layer and the still moist layer composite is dried.

Furthermore, it is alternatively possible that the previously dried foam layer is placed on the previously dried foam layer, the cover layer or on top layer and the resulting layer composite is still tempered.

Advantageously, however, the application of the cover layer to the foam layer is carried out in such a way that the cover layer is laminated onto the previously dried foam layer. For example, calendering machines can be used for lamination. The application of the cover layer takes place here vorteilhafiterweise under slight pressure to improve the adhesion of the cover layer to the foam.

In general it can be stated that a satisfactory drying speed of the Foams already at 20 ⁰ C is observed, so that drying on injured human or animal tissue is easily possible. For a faster drying and fixing of the foams, however, temperatures above 30 ^° C. should be used. Conveniently, temperatures of> 80 ^C C to <160 ⁰ C, preferably from> 100 ⁰ C to <150 ⁰ C, more preferably from> 120 ⁰ C to <140 ⁰ C. In the drying, however, temperatures of 200 ⁰ C should not exceeded, otherwise it may cause undesirable yellowing of the foams. Also possible is a two- or multi-stage drying.

The drying is usually carried out using known heating and drying equipment, such as (convection) drying cabinets, hot air or IR lamps. Drying by passing the coated substrate over heated surfaces, for example rolls, is also possible.

The application and the drying can each be carried out batchwise or continuously, but a completely continuous process is preferred.

Before being dried, the polyurethane foams can typically have foam densities of> 50 g / liter to <800 g / liter, preferably> 100 g / liter to <500 g / liter, more preferably> 100 g / liter to <350 g / liter ( Mass of all starting materials [in g] based on the foam volume of one liter).

After drying, the polyurethane foams may have a microporous, at least partially open-pore structure with cells which communicate with one another. The density of the dried foams is typically below 0.4 g / cm ³ , preferably less than 0.35 g / cm ³ , more preferably> 0.01 g / cm ³ to <0.3 g / cm ³ and most preferably is> 0, lg / cm ³ to <0.3 g / cm ³ .

The polyurethane foam layers, ie the foam layer and / or the cover layer, after drying typically have a thickness of> 0.1 mm to <50 mm, preferably> 0.5 mm to <20 mm, particularly preferably> 1 to <10 mm, most preferably> 1.5 mm to <5 mm.

The layer composite obtained can finally be deformed under pressure and heating in order to be adapted for its later intended use.

The invention further provides the use of a layer composite according to the present invention as a sports article, textile article, cosmetic article or wound dressing. Preferred is the use as a wound dressing. Advantageously, the wound dressing can be shaped so that it can be placed on body parts. An example of a body part is the heel, the forehead, the chin, the neck, the iliac crest or the buttocks. Furthermore, the body part may for example be a joint. Regarding its size, the wound dressing is the adapted to the male body part such as the heel or a joint, so for example a finger joint, an elbow joint, a knee joint or an ankle.

The present invention will be further explained with reference to the following drawings. Show it:

FIG. 1 a cross-sectional view of a layer composite according to the invention

FIG. 1 shows a cross-sectional view of a layer composite according to the invention. The foam layer 10 is designed as a polyurethane foam layer, wherein the polyurethane foam can be obtained as described. The cover layer 20, which is embodied as a thermoplastic polyurethane membrane, is in direct contact with the foam layer 10. When using the layer composite, the lower surface of the foam layer 10 is applied to the wound. The porous foam of the foam layer 10 can absorb excess exudate from the wound. Water vapor can diffuse through the cover layer 20, so that a wound healing-promoting climate in the wound can be built up. At the same time, the cover layer 20 protects the underlying foam layer 10 from contamination and germ colonization. The layer composite can then be further deformed to obtain a wound dressing adapted to a body contour.

The present invention will be further illustrated by the following examples.

Unless otherwise indicated, all percentages are by weight.

The solids contents were determined according to DIN-EN ISO 3251. NCO contents were determined volumetrically in accordance with DIN-EN ISO 11909, unless expressly stated otherwise. The "free suction" was determined by absorption of physiological saline solution according to DIN EN 13726-1, Part 3.2.

Substances used and abbreviations:

Diaminosulphonate: NH ₂ -CH ₂ CH ₂ -NH-CH ₂ CH ₂ -SO ₃ Na (45% in water)

Desmophen ^® C2200: polycarbonate polyol, OH number 56 mg KOH / g, number average molecular weight 2000 g / mol (Bayer MaterialScience AG, Leverkusen,

DE)

PolyTHF ^® 2000: Polytetramethylenglykolpolyol, OH number 56 mg KOH / g, number average

Molecular weight 2000 g / mol (BASF AG, Ludwigshafen, DE)

PolyTHF ^® 1000: Polytetramethylenglykolpolyol, OH number 112 mg KOH / g, number average molecular weight 1000 g / mol (BASF AG, Ludwigshafen, DE) Polyether LB 25: monofunctional polyether based on ethylene oxide / propylene oxide, number average molecular weight 2250 g / mol, OH number 25 mg KOH / g (Bayer MaterialScience AG, Leverkusen, DE)

Pluronic ^® PE 6800: EO / PO block copolymer, weight average molecular weight 8000 g / mol (BASF AG, Ludwigshafen, DE)

Film 1: Polyether-polyurethane membrane film, water vapor permeability (DIN

53122; 38 ° C / 90% rel. Humidity): 4500 g / (m ² xd)

Film 2: Polyether-polyurethane membrane film, water vapor permeability (DIN

53122; 38 ° C / 90% rel. Humidity): 3000 g / (m ² xd)

Film 3: Polyether-polyurethane membrane film, water vapor permeability (DIN

53122; 38 ° C / 90% rel. Humidity): 2000 g / (m ² xd)

The determination of the average particle sizes (indicated by the number average) of the polyurethane dispersion 1 was carried out by means of laser correlation spectroscopy (LKS, apparatus: Malvern Zetasizer 1000, Malver Inst. Limited).

The contents given for the foam additives relate to aqueous solutions.

Example 1 Preparation of the Polyurethane Dispersion 1

1077.2 g PolyTHF ^® 2000, 409.7 g of PolyTHF ^® 1000, 830.9 g Desmophen ^® C2200 and 48.3 g of polyether LB 25 were heated in a standard stirred apparatus at 70 ⁰ C. Subsequently, a mixture of 258.7 g of hexamethylene diisocyanate and 341.9 g of isophorone diisocyanate was added at 70 ⁰ C within 5 min and stirred at 120 ⁰ C until the theoretical NCO value was reached or slightly below. The finished prepolymer was dissolved with 4840 g of acetone while cooled to 50 ⁰ C and then a solution of 27.4 g of ethylenediamine, 127.1 g of isophoronediamine, 67.3 g of diaminosulfonate and 1200 g of water was added within 10 min. The stirring time was 10 min. It was then dispersed by adding 654 g of water. This was followed by removal of the solvent by distillation in vacuo.

The resulting polyurethane dispersion had the following properties:

Solids content: 61.6%

Particle size (LKS): 528 nm

pH (23 ° C): 7.5 Examples 2-6: Production of Foamed Foam Laminates from Polyurethane Dispersion 1

120 g of polyurethane dispersion 1, prepared according to Example 1 were mixed with 12.6 g of a 30% solution of Pluronic ^® PE 6800 in water and using a commercially available hand stirrer (stirrer made of bent wire) to 0.4 liters of foam volume pitched. Using a film applicator (doctor blade) with gap height 6 mm, the foam was mounted on non-stick paper and dried for 20 minutes at 120 ⁰ C in a convection oven. Subsequently, a film of thermoplastic polyurethane (TPU film, see table) was placed on the dried foam and fixed by gently arching the 2-layer material on the convex foam side without wrinkles and bubbles on the foam. The composite material was then tempered for 30 minutes at the temperature indicated in the table in the drying oven. Pure white film-foam laminates with good mechanical properties and fine pore structure were obtained.

n.d. : Value was not determined.

MVTR: Moisture transport rate MVTR of wound dressings according to DIN EN 13726-2, part 3.2.

TFHC: Moisture absorption and retention TFHC of a wound dressing on contact with liquid according to DIN EN 13726-1, part 3.3.

Peel strength: For the determination, 360 ° peel tests were carried out on a Zwick universal testing machine with a crosshead speed of 100 mm / min.

The examples show that laminates, which are suitable as wound dressings due to their moisture transport rate and their moisture absorption, can be laminated with membrane films.

Claims

claims

1. Layer composite, suitable as a wound dressing, comprising a foam layer (10) and a cover layer (20), wherein the cover layer (20) comprises a thermoplastic polymer and is at least partially directly connected to the foam layer (10) and wherein the foam layer (10) a polyurethane foam obtained by foaming and drying a composition comprising an aqueous, anionically hydrophilic polyurethane dispersion (I).

2. A layered composite according to claim 1, wherein the composition from which the polyurethane foam of the foam layer (10) is obtained further comprises additives selected from the group comprising fatty acid amides, sulfosuccinamides, hydrocarbon sulfonates, hydrocarbon sulfates, fatty acid salts, alkylpolyglycosides and / or ethylene oxide / propylene oxide block copolymers.

3. Layer composite according to claim 2, wherein the ethylene oxide / propylene oxide block copolymers have a structure according to the general formula (1):

HO (CH ₂ CH ₂ O) _n - (CH ₂ CHO) - (CH ₂ CH ₂ O) _n H

^CH 3

(1)

4. Layer composite according to claim 1, wherein the aqueous, anionic hydrophilic polyurethane dispersion (I) is obtainable by

Al) organic polyisocyanates and

A2) polymeric polyols having number average molecular weights of> 400 g / mol to <8000 g / mol and OH functionalities of> 1.5 to <6

and subsequently

B) the free NCO groups of the prepolymers wholly or partly with

Bl) aminofunctional, anionic or potentially anionic hydrophilicizing mittein

are reacted with chain extension and the prepolymers are dispersed in water before, during or after step B), wherein further in the reaction mixture present potential ionic groups are converted by partial or complete reaction with a neutralizing agent in the ionic form.

The layered composite according to claim 4, wherein the reaction mixture in step A) further comprises:

7. Layer composite according to claim 4, wherein in step B), the free NCO groups of the prepolymers continue to be reacted in whole or in part with

8. Layer composite according to claim 4, wherein in the preparation of the aqueous, anionically hydrophilic polyurethane dispersions (I), the component Al) is selected from the group comprising 1,6-hexamethylene diisocyanate, isophorone diisocyanate and / or the isomeric bis (4,4 '- Isocyanatocyclohexyl) methanes and wherein further component A2) comprises a mixture of polycarbonate polyols and polytetramethylene glycol polyols, wherein the proportion of the sum of the polycarbonate polyols and the Polytetramethylenglykolpolyetherpolyole to the component A2) is> 70% by weight to <100% by weight.

9. The layered composite of claim 1, wherein the thermoplastic polymer of the cover layer (20) comprises materials selected from the group consisting of polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyether, polyester, polyamide, polycarbonate, polyether-polyamide Copolymers, polyacrylate, polymethacrylate and / or polymaleate.

10. The layered composite according to claim 1, wherein the thermoplastic polymer of the cover layer (20) comprises polyurethanes which are selected from the group comprising aliphatic polyester polyurethanes, aromatic polyester polyurethanes, aliphatic polyether polyurethanes and / or aromatic polyether polyurethanes.

The layered composite according to claim 1, wherein the direct bond between the foam layer (10) and the cover layer (20) has a peel strength of 0.01 N / mm to <0.50 N / mm.

12. Layer composite according to claim 1 with a permeability to water vapor of> 1000 g / 24 hxm ² to <4000 g / 24 hxm ^second

13. A method for producing a layer composite according to claim 1, comprising the steps:

- Applying a cover layer (20) on the foam layer.

14. The method according to claim 13, wherein the application of the cover layer (20) to the foam layer is carried out such that the cover layer (20) is laminated to the previously dried foam layer.

15. Use of a layered composite according to claim 1 as a sports article, textile article, cosmetic article or wound dressing.