Blocked polyisocyanates with improved thermal stability

摘要

A blocked polyisocyanate of formula (I) contains >= 2 isocyanate gps. reversibly blocked with a monofunctional blocking agent and >= 2 isocyanate gps. in the form of thermally stable hydantoin gps. X = organic gp. having valency p which is inert towards isocyanate gps. at = 100 [deg]C. obtd. by removing aspartate gps. from a polyaspartate or an aspartate functional prepolymer; R = residue obtd. by removing the isocyanate gps. from a polyisocyanate having functionality m+1; R2 = opt. substd. hydrocarbon radical; R3 and R4 = H or organic gps., inert towards isocyanate gps. at = 100 [deg]C; B1 = residue of a reversible, monofunctional blocking agent for isocyanate gps.; m = 1-5; and p = 2-4. Also claimed is a coating compsn.contg. the blocked polyisocyanate of formula (I) and a cpd.contg. >= 2 isocyanate-reactive gps.