Patent ID: 6930161

Claim:
A self-crosslinking, branched polyurethane comprising a reaction product of an isocyanato-terminated polyurethane prepolymer and at least one compound containing on average per molecule at least two isocyanate-reactive functional groups, wherein the isocyanato-terminated polyurethane comprises a reaction product of (A) at least one hydroxyl-terminated polyester with a number-average molecular weight of from 500 to 4000 daltons, containing, based on the polyester (A), (a1) from 60 to 95% by weight of structural units derived from aliphatic starting products and (a2) from 5 to 40% by weight of structural units derived from aromatic starting products, and (B) at least one partially blocked polyisocyanate containing on average per molecule more than 1.5 and less than 3 free isocyanate groups, wherein an equivalents ratio of free isocyanate groups in the polyisocyanate (B) to hydroxyl groups in the polyester (A) is >1.