DE4308445A1 - Wound dressing based on hydrophilic polyurethane gel foams and process for their production - Google Patents

Abstract

Wound dressing with a polyurethane film as backing and with a polyurethane gel foam composed of a polyurethane gel defined in the description, of a water-absorbing material and a non-aqueous foaming agent can be used in medicine.

Description

The present invention relates to support materials applied aqueous liquids absorbing and binding polyurethane gel foams for medical applications gene, z. B. wound dressings such as wound plaster and adhesive plaster and methods for their production.

Hydrogels are macromolecular, natural or synthetic certain substances which due to a high content of hydro philen groups are able to absorb water absorptively the. The water absorption capacity of many hydrogels is the multiple of the dead weight of the anhydrous sub substance.

Hydrogels are used in a variety of forms in medicine set. They are particularly suitable for the Wundversor supply. You can protect wounds from dehydration, Absorb wound secretions, as a matrix for all kinds of active ingredients serve and also as a base for colonization with autolo gene or heterologous skin cells.  

Hydrogels can inter alia in the form of foams ver be used. Foams for the treatment of skin wounds or surgical wounds are known per se. Mainly find polyurethane foams or collagen foams Use.

However, the hydrogels of the prior art have ver various disadvantages:

Due to their hydrophilicity, most are suitable substances are soluble in water. This is usually undesirable because such products are not dimensionally stable. also Dissolve such products in an undesirable manner on Place of use and then stand for the intended purpose no longer available.

Other products are characterized by strong polymer crosslinks out. This will indeed some of the disadvantages of avoided substance class; the swellability of this However, substances are largely restricted or lost.

Even self-adhesive gel foams are known per se. These In general, they can be quite well on the skin fix, but usually have the disadvantage that their What Water absorption capacity and water retention strong are restricted.

Furthermore, hydrophilic foams are made of polyurethane gel be known. PCT application WO-88/01878 describes self-adhesive Bende polyurethane foams or polyurethane foam gels, wel contain inter alia polymerized methacrylates can. However, the production of these foam gels is done by adding water.  

Polyurethane gels based on a polyurethane matrix and higher molecular weight polyols are also disclosed in EP-B-0 057 839 described. Self-adhesive fabrics made of poly urethangeles are known from EP-B-0 147 588. The in the The two last-mentioned documents disclosed poly urethangels are not foamed. The self-adhesive gels have isocyanate numbers of 15 to 70 (EP 147 588).

It follows that the OH functionality is always in there is a clear excess.

In EP-B-57839, which does not have a self-adhesive medical Sticking plaster, but medicated gel mass or Ab was the object of molding or pouring masses, was the Foaming of such masses with air already mentioned.

The patent application EP 0 453 286 describes superabsorber foaming foam compositions. The foaming is going through here the presence of water, if necessary by adding low boiling organic solvents are reached.

EP 0 196 364 describes hydrophilic polyurethane foams which with water-absorbing polymers based on a copoly Mers of acrylic acid and potassium acetate may be filled and are intended for medical use. The polyurethane is manufactured on the basis of MDI. The used Polyether has a minimum functionality of 2 hydroxyl groups, but preferably 2 to 3 hydroxyl groups. The Ratio NCO / OH is stoichiometric. This is one Variation of the properties only very limited possible. In addition, it is not a gel-like poly urethane. Foamed with compressed air or with others, non-isocyanate reactive gases or with the aid of of low-boiling solvents. The mixture Absorber with polyether polyol takes place approximately in the  Ratio 3: 1. The foam has adhesive properties, which are completely suppressed by aluminized fleece need to be used for wound treatment.

It was an object of the invention, wound dressings such as wounds plaster and adhesive plaster with hydrogel foams for To develop wound care, which compared to the state of Technique less absorber included, an additional Ent Bonding layer basically do not need as well as a Higher property flexibility with respect to the adhesive and Have Saugverhaltens. Depending on the application area should the foamed material different self-adhesive possess properties, z. B. to the requirements below different types of sensitive skin better can. Adhesion to the moist wound surface should not take place. Another goal is different to be able to adjust its suction behavior in order to special requirements of specific types of wounds to be able to go. The absorbed liquid should also be held under slight pressure in the wound dressing. The liquid should also be as vertical as possible Wound wound surface and not distributed in the area be used to B. Macerations on sensitive wound edges to avoid. Furthermore, especially with thin foam layers the high flexibility of the self-adhesive Schäu I also used the seat in problem areas too guarantee.

This problem is solved by wound dressings, which have a Polyurethane film as a carrier and applied thereon hydrophilic polyurethane gel foams available are made

• 1. a polyurethane gel, which
  • (A) 25-62 wt .-%, preferably 30-60 wt .-%, particularly preferably 40-57 wt .-%, based on the sum of (A) and (B), a covalently crosslinked polyurethane as a high molecular weight matrix and
  • (B) 75-38 wt .-%, preferably 70-40 wt .-%, particularly preferably 60-43 wt .-%, based on the sum of (A) and (B) one or more in the matrix by secondary valence forces tightly bound Polyhydroxylverbin applications having an average molecular weight between 1000 and 12 000, preferably between 1500 and 8000, more preferably between 2000 and 6000, and an average OH number between 20 and 112, preferably between 25 and 84, particularly preferably between 28 and 56 , as a liquid dispersion medium, wherein the dispersion medium is substantially free of Hy hydroxyl compounds having a molecular weight below 800, preferably below 1000, more preferably below 1500, and optionally
  • (C) 0-100 wt .-%, based on the sum of (A) and (B), of fillers and / or additives, and which is obtainable by reacting a mixture of
    • a) one or more polyisocyanates,
    • b) one or more polyhydroxyl compounds having an average molecular weight between 1000 and 12000, and an average OH number between 20 and 112,
    • c) if appropriate, catalysts or accelerators for the reaction between isocyanate and hydroxyl groups and optionally,
    • d) from polyurethane chemistry known fillers and additives,
• wherein this mixture is substantially free of hydroxyl compounds having a molecular weight below 800, the average functionality of the polyisocyanates (F _I ) is between 2 and 4, the average functionality of the polyhydroxyl compound (F _P ) is between 3 and 6 and the isocyanate index (K) the formula in which X 120, preferably X 100, more preferably X 90 and the index K is between 15 and 70, wherein the mean values of molecular weight and OH number given are to be understood as number average,
• 2. a water absorbing material and
• 3. a substantially non-aqueous foaming agent.

The polyurethane gel foam serves as a wound dressing. Wundver Volumes according to the invention are also wound plasters and Adhesive plaster.

The polyurethane gels according to the invention can be prepared from itself from the polyurethane chemistry known Ausgangsverbin made by methods known per se who made the, how they z. B. in DE-OS 31 03 499, DE-OS 31 03 500 and EP 147 588. It is essential, however, that when selecting the gel-forming components the above de conditions are met, otherwise  instead of self-adhesive gels tack-free, elastic Gels are obtained.

Polyhydroxyl compounds preferred according to the invention are Polyether polyols, as described in the above-mentioned German Laid-open publications are mentioned in detail.

As the polyisocyanate component both (cyclo) aliphati as well as aromatic isocyanates suitable. preferred (cyclo) aliphatic polyisocyanates are 1,6-hexamethylene diisocyanate and its biurets and trimers or hydrogenated diphenylmethane diisocyanate ("MDI") types. before ferred aromatic polyisocyanates are those by Distillation can be obtained, such as MDI mixtures of 4,4'- and 2,4'-isomers or 4,4'-MDI, and tolylene diisocyanate ( "TDI") - types. The (cyclo) aliphatic and aromati isocyanates can due to modifications, for. B. Biuretization, trimerization or prepolymerization, also include higher functional shares.

The diisocyanates may in particular z. B. from the group the unmodified aromatic or aliphatic di isocyanates or from by prepolymerization with Amines, polyols or polyether polyols formed modifi selected products. Preference is given to 4,4'-di isocyanatodiphenylmethane, or else by prepolymeri tion formed with polyols or polyether polyols modified products. As very favorable has For example, by prepolymerization with tripropylene glycol liquefied 4,4'-diisocyanatodiphenylmethane proved.

Preferably, one or more polyether polyols verwen det, by addition of propylene oxide and given if ethylene oxide is available on conventional starter molecules are and how they z. B. in EP 147 588 are described.  

Preferred polyether polyols are in the following Table compiled. They were by attachment of Propylene oxide and optionally ethylene oxide to the angege Enter starter molecules Herge in a conventional manner provides.

The starter molecules for the polyether polyols are z. B. Pentaerythritol, sorbitol, trimethylolpropane or ethylene diamine.

Particularly advantageous are the catalysts or Accelerator selected from the group consisting of

• - Organic acids, in particular p-toluenesulfonic acid, n-butylphosphoric acid,  
• - Organotin compounds, including their salts organic and inorganic acids, in particular Tin naphthenate, tin benzoate, dibutyltin dioctoate, Dibutyltin diacetate, stannous II-ethylhexoate and Dibutylzinndiethylhexoat,
• - Iron salts of higher fatty acids, in particular stearate,
• Amines, for example isophoronediamine, Methylene dianiline, imidazoles,
• tertiary amines, in particular trialkylamines, where the alkyl radicals are each advantageously 2-6 Have carbon atoms.

According to the invention, the starting components are selected that in the gel-forming reaction mixture the mean NCO Functionality between 2 and 4, the average polyol Functionality between 3 and 6 and the isocyanate index between 15 and 70, preferably between 18 and 55, be more preferably between 20 and 45, lie.

The polyurethane gel foams can be optionally from the Polyurethane chemistry per se known additives enthal th, such. B. fillers and short fibers on inorganic or organic base, metal pigments, surface-active Substances or liquid diluents such as substances with a boiling point of over 150 ° C.

As inorganic fillers are, for example, heavy late, chalk, gypsum, kieserite, soda, titanium dioxide, cerium oxide, Called quartz sand, kaolin, soot and hollow microspheres.

On organic fillers z. B. Powder based of polystyrene, polyvinyl chloride, urea-formaldehyde and polyhydrazodicarbonamide. As a short fibers come z. B. glass fibers of 0.1-1 mm in length or  Fibers of organic origin, such as. B. polyester or Polyamide fibers, in question. Metal powder, such as. Eg iron or copper powder, can also be used in gelation be used. To the gels according to the invention the To impart desired coloration, those at the Ein Coloring of polyurethanes known dyes or colored pigments on an organic or inorganic basis be used, such as. B. iron oxide or Chromoxidpig pigments, phthalocyanine- or monoazo-based pigments. When Surface-active substances are z. Cellulose powder, Activated carbon and silicic acid preparations called.

As liquid diluents, for example, ethyl stearate, lauric acid, isopropyl myristate, Isopropyl palmitate or Dodecylsulfonsäureester used become.

Furthermore, as liquid extenders also higher mol kular polyols are used whose hydroxyl groups etherified, esterified or urethanized, as well Paraffin oils and silicone oils.

The content of fillers and extenders in the gel may preferably be up to 50% by weight, based on the Total weight of the gel, amount.

To modify the adhesive properties of gels optionally additives of polymeric vinyl compounds, Polyacrylates and other in the adhesive technology übli chen copolymers or adhesives based on natural substances up to a content of 10% by weight, based on the weight the gel mass, are added.

The fillers and additives can also be made from the usual Substance classes are chosen. In particular are  advantageous dyes, pigments light stabilizers, Preservatives, fragrances, antimicrobial Substances, other active ingredients such as cooling acting substances (eg, menthol) or those that the Promote blood circulation or create a feeling of warmth.

Preferred water-absorbing materials are as Su perabsorbent known water-absorbing salts of poly acrylates and their copolymers, especially the sodium or potassium salts. They can be uncrosslinked or networked and are also available as commercial products. In particular Such products are suitable as described in DE-A-37 13 601 and also superabsorber of the new Generation with only small amounts of dry out Barem water and high swelling power under pressure.

Preferred products are weakly crosslinked polymers based on acrylic acid / sodium acrylate. Such sodium Polyacrylates are available as Favor 922-SK (Chemical Factory Stockhausen GmbH, Germany).

Other absorbers, z. Carboxymethylcellulose and karaya are also suitable.

The amount by weight of the water-absorbing material can z. B. up to 1.5 times the amount by weight of the polyhydroxy connect. The amount by weight is preferably of the water-absorbent material is 24 to 67% by weight partly also 28 to 62 wt .-%, in particular 31 to 58 Wt .-%, based on the weight of Polyhydroxylverbin dung.

The water-absorbing material is preferably in finely ground form, especially when thin foam layers are desired. The particle size of the water  absorbent materials, d. H. the diameter of the overwhelming proportion of the particles of this material preferably below 300 .mu.m, preferably below 200 .mu.m, in particular but preferably less than 100 microns, especially less than 1 micron. The particle size is preferably 0.01 to 100 μm.

As non-aqueous foaming agent can be anhydrous or largely anhydrous, preferably inert gases or low-boiling solvents are used which are then in the polyurethane gel foams in finely divided form are located. It can also be mixtures of these foaming agents be used. Particularly preferred are air, stick substance or carbon dioxide or mixtures of these gases, esp but especially nitrogen. An additional foaming through a water additive is not required. Suitable Lö low-boiling solvents such as esters, Ketones, alkanes and chlorinated hydrocarbons, e.g. B. Alkyl acetates such as ethyl acetate or trichlorofluoromethane, Dichlorodifluoromethane, methylene chloride and the propellant Substitutes.

The degree of foaming can be varied by the incorporated amounts of foaming agent. Thus, the density of the foam can be adjusted to values of about 0.15-1.1 g / cm ³ . This density range is suitable for Wundbehand treatment. Depending on requirements, different densities can be set. For example, a foam can be produced which absorbs aqueous liquids very quickly. Particularly suitable foams for this purpose are from 0.30 to 0.65 g / cm ³ , but in particular from 0.45 to 0.6 g / cm ³ (a).

Foam densities of from 0.6 to 0.9 g / cm ³ , but in particular from 0.65 to 0.8 g / cm ^{3, are} advantageous for a foam product with a high absorption capacity but only a moderately rapid intake behavior (b).

For products with slow suction characteristics densities of 0.8 to 1.0 g / cm ³ , in particular from 0.85 to 0.95 g / cm ^{3 are} well suited at high capacity (c).

Preferably, all starting materials used are water free or largely anhydrous or as industrial scale Products low in water. But are also suitable hydrous Substances in which the water is bound so that it does not responding.

Advantageously, the foams of the invention are available out

20-95% by weight of polyhydroxyl compound,
1-30% by weight of polyisocyanate,
1-60% by weight of superabsorbent,
0.0001-10% by weight accelerator

and the non-aqueous foaming agent in an amount giving densities of 0.15 to 1.1 g / cm ³ , in particular the densities given above, depending on which suction behavior is desired.

The foams according to the invention are therefore preferably obtained out

55-85% by weight of polyhydroxyl compound,
2-15% by weight of polyisocyanate,
5-40% by weight of superabsorbent,
0.001-1 wt% accelerator

and the non-aqueous foaming agent in such Lot, that

• (a) densities of 0.30 to 0.65 g / cm ³ , but especially 0.45 to 0.6 g / cm or
• (b) densities of 0.6 to 0.9 g / cm ³ , but especially 0.65 to 0.8 g / cm ³ or
• (C) densities of 0.8 to 1.0 g / cm ³ , but in particular 0.85 to 0.95 g / cm ³ are obtained.

These density ranges correspond to the above under (a) - (c) given properties.

Numerical values for the foaming agent quantities are themselves in wide limits do not make sense, as these always depending on the example per minute ejected amount of material to be foamed, In addition, density fluctuations of the material to be foamed and solubility or outgassing phenomena in Dependence on the quality of raw materials due to production possible are.

Therefore, in principle, by trial and error, the density what to do with suitable technical equipment within minutes and no one skilled in the art Difficulties.

It is advantageous to weight ratios of poly hydroxyl compound: polyisocyanate of (5-35): 1 to especially about (10-25): 1. The pot life as Measure of the processability of these materials lies between 0.5 and 30 minutes.  

The polyether polyols used can, for example Commercial products such as Levagel VP SN 100 and Diiso cyanate have become commercial products like Desmodur PF, Desmodur N 100, IPDI and Desmodur W proved to be suitable (Commercial products of Bayer AG).

For the accelerator, so the dibutyltin dilaurate is Desmorapid Z / SN, for tin II-ethylhexoate Desmorapid SO advantageous commercial product (Bayer AG).

The invention also provides the process for Preparation of the polyurethane foams of the invention, the characterized in that one

• 1. the ones mentioned above under 1. and defined Components (A), (B) and (C) and a), b), c), and d) of Polyurethangeles,
• 2. a water absorbing material and
• 3. a nonaqueous foaming agent

combined and mixed with each other and foams, using gases introduced during mixing, in particular stirred or beaten and introduced solutions by foaming in the mass the foaming bewir ken, to which the mass is optionally heated.

The heating is preferably carried out in the given if subsequent curing process, especially at Temperatures from 200 to 140 ° C and times of 24 hours up to a few seconds.

The preparation of the gels can in particular according to EP 147 588 done in different ways.  

You can z. B. after the one-shot or the prepolymer Ver drive work. In the one-shot process, all Kom components, d. H. Polyols, di- and / or polyisocyanates, the Isocyanate polyaddition reaction accelerating catalyst gates and optionally fillers and additives and the other components at once and inten mixed together.

In the prepolymer process, two modes of operation are possible. Either one first produces an isocyanate prepolymer, by adding a corresponding proportion of the amount of polyol the total, intended for gelation isocyanate reacted and then adds the obtained prepolymer, the residual amount of polyol and optionally fill and Additives and the other components and mixes intensive. Or you put the whole, for the gelation provided amount of polyol with a portion of the isocyanate amount to a hydroxyl prepolymer and then mix ßend the remaining amount of isocyanate.

An inventively particularly advantageous mode of operation is a variant of the one-shot process and the Hydroxyl Prepoylmer method. Here, the polyol or polyol mixture, optionally the filler and additive substances and the other components of the catalyst and zusammenge together two different diisocyanates in one shot give and mixed thoroughly, with a diisocyanate ali of a phatic nature. One can assume that through the strongly different reactivity of the two diiso cyanate initially a Hydroxylprepolymer arises, the then within minutes with the other diisocyanate reacted under gelation.

In these procedures, the promotion, dosage and mixing and foaming of the individual components and the  remaining components or component mixtures with the for the person skilled in polyurethane chemistry known per se Devices take place.

Foaming with a nonaqueous foaming agent preferably by stirring or blowing in air known in itself, but offers here in particular special Advantages:

The advantageous polyurethane gels according to the invention can easily become weakly adhesive and good on themselves sticking to very well adhesive by variations of the Ratio of polyhydroxyl compound to isocyanate being controlled. By lowering the added Isocyanate amount, based on the polyhydroxyl compound increases the bond strength and by increasing the zugege If the amount of isocyanate is reduced, the bond strength is reduced. These exact control is only possible in a simple way when working essentially anhydrous. The reason this is due to the extremely high water absorption capacity Superabsorber, since added water, the for the Foaming process must be available, in a unkon trolled way can be deprived of the process and becomes, so that it is much more difficult, the productsi targeted employment.

The wound dressings according to the invention with the erfindungsge proper foam material meet all requirements gene.

Surprisingly, the Gelschäu invention Me the feature that they stick in the moist wound environment de completely lose properties. Besides, it is easily possible, a fast, medium or slow To obtain suction at high absorption capacity. The  Foam is weak or strongly self-adhesive, so that It can be adapted to different skin types. Very important is that the absorbed material is practical is not distributed in the area of the wound dressing.

The foams can be ausgegos sen after a preferably about 0.5-30 minutes measuring pot life to flat structures or streaked. In this way, foam thicknesses of 0.015 mm to 15 cm are easily accessible. The strength of the material is in turn dependent on the intended purpose: if a large amount of liquid is to be absorbed per unit area, a correspondingly thick foam material is painted. If only a small volume of liquid per unit area is to be supplied, even very thin layers are sufficient. The degree of freedom "thickness" it is necessary because the liquid absorbed in wesentli chen is absorbed perpendicular to the wound surface and is not distributed in the area. Through the use of finely ground absorber thin mass orders of up to 10 g / m ² can be produced well when passing. However, it is also possible and advantageous to make objects from the hydrogel foams according to the invention, which are not flat but pronounced space-filling, for example by conventional casting.

The resulting foams are open-celled foams. It is so not necessary to cut them into such convert.

Advantageously, the hydrogel foams of the invention according to known methods on the sheet carrier be applied.

According to the invention can be used as a carrier polyurethane films use, since this is the high flexibility of  Polyurethane hydrogel foams by the flexible carrier material rial is not hindered and thus also in the joint area good adhesion. Such polyurethane films are known and in Trade available.

Very beneficial come through the open-pore foam structure also water vapor permeabilities and permeable to air the substrates used, the the per se given permeabilities for water vapor and air of the polyurethane hydrogels, so that as well the permeability of the pure carrier is achieved. Also Here is therefore by variation z. B. the film thickness and -art a targeted control of these properties possible.

The polyurethane gel foams of the invention have self Adhesive properties, especially on skin. Very strong Foaming gels stick pleasantly on the skin and leave remove painless from normal skin.

For extremely sensitive skin, however, are weak sticking de producing foams that have sufficient adhesion so that they can adhere and be easily fixed NEN. Skin damage even in extremely sensitive skin not observed.

The films according to the invention can have a high degree of flexibility, since the foam gel also has these properties. In addition, the good skin compatibility of Kle Bonds is used. Microporous polyurethane films are used particularly advantageously since these films have special properties. These films are preferably germ-proof. Their air and water vapor permeability is variable. So z. For example, a polyurethane film having a thickness of about 35 microns and a water vapor Luftdurchläs ty is 3500g / m ^2/24 hours. The Wasserdampfdurchläs sigkeit a 25 .mu.m thick film is 6500g / m ^2/24 hours. A 50 .mu.m thick film has a water vapor permeability of 2100g / m ^2/24 hours. These types of foils are all highly flexible, so that the high flexibility of the gel foam masses comes into its own.

A preferred wound dressing according to the invention comprises a polyurethane film provided with a polyurethane gel foam layer according to the invention. The thickness of the water foam gel layer can be 0.1-10 mm, but preferably 0.5-6 mm and more preferably 2-4 mm and can be tuned with the desired capacity. The foam density may be 0.25 to 0.7 g / cm ³ , preferably 0.3 to 0.65 g / cm ³ , but in particular 0.45 to 0.6 g / cm ³ . The fluid intake takes place very quickly. Within 90 minutes, preferably 10 to 60 g of water / g of foam gel, more preferably 15 to 50 g of water / g of foam gel, but especially 20 to 40 g of water / g of foam gel are added. The total absorption capacity is preferably at least 20 g water / g foam gel, in particular at least 30 g water / g foam gel and particularly preferably at least 40 g water / g foam gel. The poly urethane gel foam layer has only weak or very low self-adhesive properties. Thus, the bond strength can be up to 0.8 N / cm (measured on steel), preferably 0.06 to 0.6 N / cm (steel), particularly preferably 0.1 to 0.5 N / cm (steel).

Depending on the quality of the raw materials used here, based on the amount by weight of polyhydroxyl used compounds preferably 4.7-6.9 wt .-%, preferably 5.0-6.4 wt .-%, but especially 5.4-5.9 wt .-% of Isocyanate added as a crosslinker.  

The weight fraction of polyhydroxyl compounds, based on the total weight of raw materials used, can between 60 and 80% by weight, preferably between 63 and 77 Wt .-%, but especially between 65 and 75 wt .-% lie.

The proportion by weight of superabsorber, based on the Ge total weight of raw materials used, can be between 20 and 40 wt .-%, preferably between 23 and 37 wt .-%, ins special but between 25 and 35 wt .-% amount.

This wound dressing is suitable for very sensitive skin net, whereby the skin surface in partial areas destroyed can be and secretes a lot of secretion. A clear Distribution of secretions over the edge of the wound or moistness rich does not take place. A fixation can at For example, in addition with non-adhesive fixation aid take place.

Especially important for the application is that the Ma material can be removed in one piece. Because of his low bond strength, it also finds it in geschä gescha Dermal skin an ideal application.

Also on hairy body parts is the material Greatly usable, since it is essentially without Pulling the hair off and even almost can be removed painless, as hair when removing the Materials are only temporarily pulled weakly.

Another preferred wound dressing according to the invention comprises a polyurethane film which is provided with a erfindungsge MAESSEN polyurethane gel foam layer whose thickness can be 0.05 to 3 mm, preferably 0.1 to 2 mm, but in particular 0.2 to 1, 5 mm. The foam density may be 0.55 to 0.9 g / cm ³ , preferably 0.6 to 0.85 g / cm ³ , but in particular 0.65 to 0.8 g / cm ³ . The fluid intake is also fast. Within half of 90 min. Preferably 5 to 50 g of water / g foam gel, more preferably 7 to 40 g of water / g foam gel and in particular 10 to 30 g of water / g foam gel taken. The total absorption capacity is preferably at least 15 g of water / g of gel foam, in particular at least 25 g of water / g of foam gel and particularly preferably at least 40 g of water / g of foam gel. The polyurethane gel foam layer has good self-adhesive properties. Thus, the bond strength can be 0.3 to 2.5 N / cm (measured on steel), preferably 0.5 to 2 N / cm (steel) and particularly preferably 0.6 to 1.7 N / cm. Despite these low adhesion values measured on steel, the material adheres perfectly to intact skin. The excellent additional properties listed for the low-foaming foam also apply to this more adhesive foam variant.

Depending on the quality of the raw materials used here, based on the amount by weight of polyhydroxyl used compound preferably 4.4-6.4% by weight, preferably 4.6% 6.1 wt .-%, but especially 5.0-5.6 wt .-% of Isocyanate added.

The weight fraction of polyhydroxyl compounds, based on the total weight of raw materials used, can between 60 and 80% by weight, preferably between 63 and 77 Wt .-%, but especially between 65 and 75 wt .-% lie.

The proportion by weight of superabsorber, based on the Ge total weight of raw materials used, can be between 20  and 40 wt .-%, preferably between 23 and 37 wt -%, ins special but between 25 and 35 wt .-% amount.

The wound dressing adheres well to the joints, in particular especially the hand, because he is very flexible.

A third preferred wound dressing is the same as before standing described, stronger self-adhesive dressing, but preferably has a foam gel layer with a Thickness of 0.01 to 1 mm, in particular 0.05 to 0.7 mm and more preferably 0.1 to 0.5 mm. The remaining features and properties are as described above the stronger self-adhesive bandage. The very thin one and flexible wound dressing serves to smudging out To prevent passing residual amounts of Wundsekreten and he has so z. B. the function of a protective cover. Because the The cover is watertight, also makes a short-term Contact with water no problems.

For the three above wound dressings are polyurethane films with thicknesses of 10-100 microns preferred.

As the carrier according to the invention of the polyurethane foam gel waterproof, but water vapor permeable, flexible Polyurethane films are particularly preferred. This applies in particular dere for the above-described preferred Wundver associations.

Such films can z. B. be made of poly ester polyols and / or polyether polyols and / or others Polyol compounds with a minimum functionality of 2, those with aliphatic or aromatic polyisocyanates in pure or prepolymerized form and a minimum radio tionality of 2 are networked.  

Such films preferably have thicknesses of 5-200 .mu.m, preferably 10 to 100 .mu.m, more preferably 15 to 70 .mu.m. The values for the water vapor permeability preferably from 500 to 10,000 g / m ^2/24 hr, preferably 700 to 7000g / m ^2/24 hours, in particular 1000 to 5000 g / m ^2/24 hr.

The invention further provides a method for Production of self-adhesive fabrics based on of polyurethane gel foam coated backings. The Method is characterized in that the above defined foams or capable of Schaumgelbildung Reaction mixtures on the surface of a support material applies, z. B. direct method or reversal method by pouring or knife coating, the surface with the gel-forming reaction mixture, if appropriate only partially is covered. The layer thickness of the gel foam can, for. B. 0.01 mm to 150 mm, as the case may be described, which suction capacity per unit area is desired.

The preparation of the fabrics according to the invention can carried out continuously or discontinuously. The Working method depends on the given, with a detention Layer to be provided from layer. If you want has already tailored carrier materials is present is often a discontinuous operation advantageous. The continuous working method is recommended in the Coating of support materials in endless form, z. B. as a roll, present. The order of foam Adhesive layer on the substrate can be directly or take place after the reversal process. The reaction mixture can also be found in the mentioned method before it passes through the reaction freezes, sails.  

Although the cohesion of the foams of the invention is good, can be a post-treatment of the foams of the invention and Fabrics by the irradiation with gamma rays, whereby the cohesion in the gel layer is improved can, be beneficial.

Although it is possible, as mentioned, the adhesive properties to control the foams of the invention, so that he Keep foams or coated therewith well can be self-adhesive, they can be beneficial one of the two or both large areas with a conventional self-adhesive be coated.

The invention is also the use of polyurethane gel foams according to the invention or the so produced self-adhesive sheet with carriers made of polyurethane foils as wound dressings.

They can serve, for example, surface wounds or to care for surgical wounds. Besides, they are suitable as a blister patch. They protect by their pole effect the intact skin blister, z. For burns, and cover the wound area when the bladder opens Has.

In the context of the present application are, if not otherwise stated, all amounts and percentages on the Weight and total composition of the preparation based.

The following examples are intended to explain the invention but without intending to embody the invention to restrict these examples.  

Examples

The following reaction components are in a commercial available foam mixing head with commercially available Baren dosing combined and in this intimately mixed. Then the mass is applied to a siliconizer tes paper and with a polyurethane film covered. Then allowed to mass at 80 ° C ausrea yaw. To investigate the properties of the separation paper removed.

example 1 Polyetherpolyol (Levagel VP SN 100) | 100 kg Superabsorber (Favor SAB 922-SK) 38 kg dibutyltindilaurate 0.02 kg Diisocyanate (Desmodur PF) 5.7 kg

Nitrogen, so that a density of 0.52 g / cm ^{3 is} obtained. For this purpose, about 180-230 l of nitrogen are suitable. Fluctuations occur because production-related partial quantities of nitrogen can outgas.

The result is a slightly adhesive, open-pore foam. The material can after 90 minutes about 35 g of water per Take up grams of its own weight. The adhesive force on Steel is about 0.3 N / cm. The layer thickness is approx. 3 mm. The liquid is essentially vertical sucks and practically not discharged to the side.

The foam can be additionally fixed. The water vapor transmission rate is about 1/3 of the original water vapor permeability of 6,500 g / m ^2/24 h, the polyurethane film. The film thickness is about 25 microns. The film is commercially available (Rexham PU 77).

Example 2 Polyetherpolyol (Levagel VP SN 100) | 100 kg Superabsorber (Favor SAB 922-SK) 38 kg dibutyltindilaurate 0.02 kg Diisocyanate (Desmodur PF) 5.3 kg

Nitrogen, so that a density of 0.71 g / cm ^{3 is} obtained. For this purpose, about 80-130 liters of nitrogen are suitable. Fluctuations occur because production-related subsets of nitrogen outgassing can.

The result is a skin with good adhesion, open-pored Foam. The material can after about 90 minutes about 17 g of water per gram of its own weight. The adhesive power on steel is around 1.1 N / cm. The layer thickness is about 0.75 mm.

The layer thickness of the polyurethane film (Rexham PU 77) is about 25 microns and has a water vapor permeability of about 6500 g / m ^2/24 hr. It reduces by applying the mass by about 60%.

Example 3 Polyetherpolyol (Levagel VP SN 100) | 100 kg Superabsorber (Favor SAB 922-SK) 38 kg dibutyltindilaurate 0.02 kg Diisocyanate (Desmodur PF) 5.3 kg

Nitrogen, so that a density of 0.66 g / cm ^{3 is} obtained. For this purpose, about 100 to 150 l of nitrogen are suitable. Fluctuations occur because production-related partial quantities of nitrogen can outgas.

This gives a very good adhesion to skin foam. The bond strength to steel is determined to be about 0.6 N / cm. The water absorption is about 13 g of water / g sample. There was a polyurethane film of 50 microns thickness having a water vapor permeability of 2100 g / m ² / 24h used (Rexham 91i) The layer thickness is 0.2 mm.

Are in the above examples according to the invention instead of nitrogen other gases such as air or gas mixtures or carbon dioxide used, we obtain appropriate Results.  

With the foams described above and the Foam-coated carriers are excellent absorbent wound plasters and wound dressings.

Claims (19)

1. Wound dressings, comprising a polyurethane film as Trä ger and applied thereon hydrophilic Polyurethanangel foams, which are available from

• 1. a polyurethane gel, which
  • (A) 25-62 wt .-%, preferably 30-60 wt .-%, particularly preferably 40-57 wt .-%, based on the sum of (A) and (B), a covalently crosslinked polyurethane as a high molecular weight matrix and
  • (B) 75-38 wt .-%, preferably 70-40 wt .-%, more preferably 60-43 wt .-%, based on the sum of (A) and (B) one or more in the matrix by Secondary valence forces tightly bound polyhydroxyl compounds having an average molecular weight between 1000 and 12 000, preferably between 1500 and 8000, particularly preferably between 2000 and 6000, and a mitt sized OH number between 20 and 112, preferably between 25 and 84, more preferably between 28 and 56, as a liquid dispersing agent, wherein the dispersing agent is substantially free of hydroxyl compounds having a molecular weight below 800, preferably below 1000, more preferably be below 1500, and given if
  • (C) 0-100 wt .-%, based on the sum of (A) and (B), of fillers and / or additives, and which is obtainable by reacting a mixture of
    • a) one or more polyisocyanates,
    • b) one or more polyhydroxyl compounds having an average molecular weight between 1000 and 12000, and a mean OH number between 20 and 112,
    • c) optionally catalysts or accelerators for the reaction between isocyanate and hydroxyl groups and optionally
    • d) from polyurethane chemistry known fillers and additives,
• wherein this mixture is substantially free of hydroxyl compounds having a molecular weight below 800, the average functionality of the polyisocyanates (F _I ) is between 2 and 4, the average functionality of the polyhydroxyl compound (F _P ) is between 3 and 6 and the isocyanate index (K) the formula in which X 120, preferably X 100, more preferably X 90 and the index K is between 15 and 70, wherein the mean values of molecular weight and OH number given are to be understood as number average,
• 2. a water absorbing material and
• 3. a substantially non-aqueous foaming agent.

2. Wound dressing according to claim 1, characterized in that the polyurethane gel

• (A) 30-60% by weight, based on the sum of (A) and (B), of the covalently crosslinked polyurethane and
• (B) 70-40% by weight, based on the sum of (A) and (B), containing polyhydroxyl compounds as the liquid dispersant.

3. wound dressing according to claim 1, characterized in that the polyurethane gel

• (A) 40-57% by weight, based on the sum (A) and (B), of the covalently crosslinked polyurethane and
• (B) 30-43% by weight, based on the sum (A) and (B), containing polyhydroxyl compounds as the liquid dispersant.

4. Wound dressing according to claim 1, characterized the polyhydroxyl compounds are polyether polyols. 5. wound dressing according to claim 1, characterized that the diisocyanates are selected from the group of unmodified aromatic or aliphatic diiso cyanates, for example 4,4'-diisocyanatodiphenylmethane, and by prepolymerization with polyols or poly ether polyols formed, modified products,  for example, by prepolymerization with tri propylene glycol liquefied 4,4'-diisocyanatodiphenyl methane. 6. Wound dressing according to claim 1, characterized in that the accelerators are selected from the group consisting of

• Organic acids, in particular p-toluenesulfonic acid, n-butylphosphoric acid,
• Organotin compounds, including their salts of organic and inorganic acids, in particular tin naphthenate, tin benzoate, dibutyltin dioctoate, dibutyltin diacetate, tin (II) ethylhexoate and dibutyltin dimethylhexoate,
• Iron salts of higher fatty acids, in particular iron stearate,
• Amines, for example isophoronediamine, methylenedianiline, imidazoles,
• tertiary amines, in particular trialkylamines, the alkyl radicals in each case advantageously having 2-6 carbon atoms.

7. Wound dressing according to claim 1, characterized that the water-absorbing material is a superabsorber is. 8. Wound dressing according to claim 1, characterized that the non-aqueous foaming agents nitrogen, air or carbon dioxide or mixtures of these gases. 9. wound dressing according to claim 1, characterized in that the polyurethane gel foam is obtainable from 20-95 wt .-% polyhydroxyl compound,
1-30% by weight of polyisocyanate,
1-60% by weight of superabsorbent,
0.0001-10 wt% accelerator and the nonaqueous foaming agent in an amount giving densities of 0.15 to 1.1 g / cm ³ . 10. Wound dressing according to claim 1, characterized in that the polyurethane gel foam is obtainable from 55-85 wt .-% polyhydroxyl compound,
2-15% by weight of polyisocyanate,
5-40% by weight of superabsorbent,
0.001-1% by weight of accelerator and the nonaqueous foaming agent in an amount giving densities of 0.3 to 1.0 g / cm ³ , in particular densities of 0.30 to 0.65 g / cm ³ , 0.6 to 0.9 g / cm ³ or 0.8 to 1.0 g / cm ³ . 11. A process for the preparation of wound dressings according to claim 1, characterized in that

• 1. the components (A), (B) and (C) mentioned above under 1. and a), b), c), and d) of the polyurethane gel,
• 2. a water absorbing material and
• 3. a nonaqueous foaming agent

united and mixed with each other and foams and on one Apply polyurethane film.   12. Use of the wound dressings according to claim 1 in the Medicine, in particular as a plaster, wound plaster or Blister. 13. wound dressing according to claim 1, characterized that the amount by weight of the water-absorbing material 24-67% by weight, based on the weight of the poly hydroxyl compound. 14. Wound dressings according to claim 1, characterized in that the foam density is 0.3 to 0.65 g / cm ² , 0.6 to 0.9 g / cm ³ or 0.8 to 1.0 g / cm ³ . 15. Wound dressing according to claim 1, characterized in that

• the thickness of the foam gel layer is 0.1-10 mm,
• the foam density is 0.25 to 0.7 g / cm ³ ,
• the water absorption in 90 minutes is 10-60 g water / g foam gel,
• - the total capacity is at least 20 g / water / g foam gel and
• - the bond strength is up to 0.8 N / cm (measured on steel).

16. Wound dressing according to claim 1, characterized in that

• the thickness of the foam gel layer is 0.05-3 mm,
• the foam density is 0.55 to 0.9 g / cm ³ ,
• the water absorption in 90 minutes is 5-50 g water / g foam gel,
• - the total absorption capacity is at least 15 g / water / g foam gel and
• the bond strength to 0.3-2.5 N / cm (measured on steel),

is. 17. Wound dressing according to claim 1, characterized in that

• the thickness of the foam gel layer is 0.01-1 mm,
• the foam density is 0.55 to 0.9 g / cm ³ ,
• the water absorption in 90 minutes is 5-50 g water / g foam gel,
• - the total absorption capacity is at least 15 g / water / g foam gel and
• - the bond strength is 0.3-2.5 N / cm (measured on steel).