Fast-curing alkoxysilane spray foams

1. An isocyanate-free multicomponent system for producing foams for medical products, having at least two separate components, the first component comprising at least one alkoxysilane-terminated prepolymer, and the second component comprising an aqueous component, with the aqueous component having a pH of 4.0 to 9.5 at 20° C., wherein the aqueous component comprises at least one acid, one base, or one buffer system, wherein the aqueous component comprises a polyurethane dispersion comprising 5 to 65 wt % of polyurethane based on the total weight of the polyurethane dispersion, wherein the alkoxysilane-terminated prepolymer comprises an alkoxysilane-terminated polyurethane prepolymer prepared from [(cyclohexylamino)methyl]triethoxysilane and an isocyanate-terminated prepolymer prepared from a polyol component and an aliphatic isocyanate component.

2. The multicomponent system as claimed in claim 1 , wherein the aqueous component has a pH of 4.5 to 8.0 at 20° C.

3. The multicomponent system as claimed in claim 1 , wherein the aqueous component comprises at least one buffer system.

4. The multicomponent system as claimed in claim 3 , wherein the concentration of the buffer system is 0.001 to 2.0 mol/l.

5. The multicomponent system as claimed in claim 3 , wherein the buffer system possesses a buffering capacity of at least 0.01 mol/l.

6. The multicomponent system as claimed in claim 1 , wherein the aqueous component comprises a thickener selected from the group consisting of starch, starch derivatives, dextrin derivatives, polysaccharide derivatives, cellulose, cellulose derivatives, cellulose ethers, cellulose esters, organic wholly synthetic thickeners based on polyacrylic acids, polyvinylpyrrolidones, poly(meth)acrylics, or polyurethanes, inorganic thickeners, and mixtures thereof.

7. The multicomponent system as claimed in claim 1 , wherein the alkoxysilane-terminated polyurethane prepolymer comprises a polyesterpolyol and/or polyetherpolyol, the fraction of ethylene oxide units in the polyetherpolyol being more not more than 50 wt %.

8. The multicomponent system as claimed in claim 1 , wherein the weight average of the alkoxysilane-terminated prepolymer is 500 to 20 000 g/mol.

9. The multicomponent system as claimed in claim 1 , wherein the polyurethane dispersion comprises 20 to 65 wt % of polyurethane.

10. The multicomponent system as claimed in claim 1 , wherein the weight-average of the polyurethane in the polyurethane dispersion is 10 000 to 1 000 000 g/mol.

11. The multicomponent system as claimed in claim 1 , wherein the first and/or the second component comprises an active medical ingredient selected form the group consisting of substances that release nitrogen monoxide under in vivo conditions, vitamins, provitamins, carotenoids, analgesics, antiseptics, hemostyptics, antihistamines, antimicrobial metals or salts thereof, plant-based wound healing promoter substances or substance mixtures, plant extracts, enzymes, growth factors, enzyme inhibitors, and combinations thereof.

12. The multicomponent system as claimed in claim 1 , wherein the first and the second component of the composition are present in a volume ratio of 10:1 to 1:10 to one another.

13. The multicomponent system as claimed in claim 1 , wherein the first and/or the second component comprises in each case a propellant gas, wherein the propellant gas is selected from the group of dimethyl ether, alkanes, and mixtures thereof.

14. The multicomponent system as claimed in claim 1 , the dynamic viscosity of the aqueous component at 23° C. is from 300 to 1000 mPas.