Production of polyurethane foams for wound management

1. A process for producing a wound dressing foam, comprising providing a composition comprising:

(a) silane-terminated polyurethane prepolymers (I) obtained by reacting:

(i) polyurethane prepolymers (A) having free isocyanate groups to an average NCO functionality of at least 1.5 with;

(ii) di- and/or trialkoxysilanes (B) having amino, hydroxyl and/or thiol groups bonded to the silicon atom via an alkylene radical; or

(iii) polyhydroxy compounds (C) having an average OH functionality of at least 1.5 with;

(iv) di- and/or trialkoxysilanes (D) having isocyanate and/or isothiocyanate groups bonded to the silicon atom via an alkylene radical comprising more than one alkoxysilane group;

(b) (foam) additives (II);

(c) optionally catalysts (III);

(d) optionally blowing agents (IV), and also

(e) optionally further, auxiliary and adjunct materials (V);

wherein the composition is foamed, applied to skin before, during or after foaming, and cured in the presence of water, and

wherein said wound dressing foam has a density of less than 0.4 g/cm 3 and

wherein water is added for curing, in an amount such that the molar ratio of alkoxysilane groups in the silane-terminated prepolymer to added water is less than or equal to 1.

2. A wound dressing foam on an animal or human skin obtained by the process as claimed in claim 1 and comprising a silane-terminated polyurethane prepolymer, wherein said wound dressing foam has a density of less than 0.4 g/cm 3 , and wherein said wound dressing foam is present on the animal or human skin.

3. The process according to claim 1 , wherein the silane-terminated prepolymers (I) are based on polyisocyanates or polyisocyanate mixtures having exclusively aliphatically and/or cycloaliphatically bound isocyanate groups and an average NCO functionality of 2 to 4.

4. The process according to claim 1 , wherein the additives (II) comprise nonionic surfactants based on polyether siloxanes.

5. The process according to claim 1 , wherein the compositions to be foamed comprise, based on dry substance, 85 to 99.9 parts by weight of silane-terminated polyurethane prepolymer (I) and 0.1 to 15 parts by weight of the (foam) additive (II) and also 0 to 50 parts by weight of auxiliary and adjunct materials (V).

6. A wound dressing foam obtained by the process of claim 1 .

7. A wound dressing foam obtained by the process of claim 1 and comprising a silane-terminated polyurethane prepolymer, wherein said wound dressing foam is adhered to or laminated with or coated with a permeable or semi-permeable film.

8. A wound dressing foam obtained by the process of claim 1 and comprising a silane-terminated polyurethane prepolymer, wherein said wound dressing foam comprises an antimicrobially or biologically active component.

9. The wound dressing foam of claim 2 , wherein said wound dressing foam has a density of less than 0.35 g/cm 3 .

10. The wound dressing foam of claim 2 , wherein said wound dressing foam has a density in the range of from 0.01 to 0.2 g/cm 3 .

11. The process of claim 1 , wherein said wound dressing foam has a density of less than 0.35 g/cm 3 .

12. The process of claim 1 , wherein said wound dressing foam has a density in the range of from 0.01 to 0.2 g/cm 3 .

13. The process according to claim 4 , wherein the compositions to be foamed comprise, based on dry substance, 85 to 99.9 parts by weight of silane-terminated polyurethane prepolymer (I) and 0.1 to 15 parts by weight of the (foam) additive (II) and also 0 to 50 parts by weight of auxiliary and adjunct materials (V).

14. The process according to claim 13 , wherein the silane-terminated prepolymers (I) are based on polyisocyanates or polyisocyanate mixtures having exclusively aliphatically and/or cycloaliphatically bound isocyanate groups and an average NCO functionality of 2 to 2.4.

15. The process according to claim 1 , wherein component C includes the addition of styrene oxide, ethylene oxide, propylene oxide, butylene oxide or epichlorohydrin or a mixture thereof.

16. The process according to claim 1 , wherein component C includes the addition of ethylene oxide and propylene oxide in an amount from 10 to 65% by weight.

17. The process according to claim 1 , wherein component C includes the addition of ethylene oxide and propylene oxide in an amount from 10 to 30% by weight.

18. The process according to claim 14 , wherein component C includes the addition of ethylene oxide and propylene oxide in an amount from 10 to 30% by weight.

19. The process according to claim 1 , wherein the molar ratio of alkoxysilane groups in the silane-terminated prepolymer to added water is less than 1.

20. The process according to claim 18 , wherein the molar ratio of alkoxysilane groups in the silane-terminated prepolymer to added water is less than 1.