Patent ID: 8829122

Claim:
Impact strength modifier comprising an isocyanate group-containing polyurethane polymer (PU1), which is synthesized from at least one polyisocyanate and at least one amphiphilic block copolymer having at least one hydroxyl group, and optionally at least one compound with at least two NCO— reactive groups, wherein the impact strength modifier has formula (I) wherein Y 1 stands for a linear or branched polyurethane polymer PU1 terminated by m+m′ isocyanate groups, after removal of all terminal isocyanate groups; Y 2 each independently stands for a blocking group which is cleaved at a temperature above 100° C.; Y 3 each independently stands for a group of formula (I′) wherein R 4 stands for an aliphatic, cycloaliphatic, aromatic, or araliphatic epoxide containing a primary or secondary hydroxyl group, after removal of the hydroxy and epoxy groups; p=1, 2, or 3 and m and m′ each stand for numbers from 0 and 8, provided that m+m′ stands for a number from 1 to 8, and wherein the amphiphilic block copolymer having at least one hydroxyl group is a block copolymer derived from ethylene oxide and/or propylene oxide as well as at least one other alkylene oxide with at least 4 C atoms.