Patent ID: 6166164
Filing Date: 2000-12-26
Classification: C08G

Abstract:
A polyurethane powder coating comprising a partially or totally 1,2,4-triazole-blocked polyisocyanate and a hydroxyl-containing polyester, wherein the blocked polyisocyanate is a physical mixture of (1) an aliphatic urethane- or isocyanurate-functional polyisocyanate and (2) a (cyclo)aliphatic or cycloaliphatic urethane-or isocyanurate-functional polyisocyanate, wherein the physical mixture of the polyisocyanates contains no mixture of two or more isocyanurate-functional polyisocyanates, wherein the isocyanate groups are blocked in such a way that there is from 0.5 to 1 mol of 1,2,4-triazol per isocyanate equivalent, and the ratio by weight of aliphatic to (cyclo)aliphatic and cycloaliphatic polyisocyanates is from 90 to 10 to 10 to 90, and the hydroxyl-containing polyester has a functionality of .gtoreq.2, an OH number of from 30 to 150 mg KOH/g, a viscosity <40,000 mPa.s at 160.degree. C. and a melting point of from 75 to 100.degree. C., and wherein either(A) component (1) is an aliphatic isocyanurate-functional polyisocyanate, or(B) component (2) is a cycloaliphatic urethane-functional polyisocyanate, or(C) component (2) is a cycloaliphatic isocyanurate-functional polyisocyanate.