| abstract |
Water vapour-permeable coatings based on polyurethane can be formed from heat-curable compositions containing n n A) a ketoxime-blocked prepolymer containing NCO groups and based on polyisocyanates and polyhydroxyl components, n B) a crosslinking agent of the formula n<IMAGE>n in which R or R<1> is H or alkyl, n where the equivalent ratio between blocked NCO groups in A) and NH2 groups in B) is between 1.35:1 and 0.95:1, and where at least one of the polyhydroxyl compounds contains, in stable dispersion, a polyurethane and/or a polyurethane-urea and/or a polyurea which contain virtually no free NCO, OH or amino groups and are built up from diisocyanates and from diamines, hydrazine and/or diols. At least one of these components must contain a hydrophilising radical. |