BINDER COMPOSITIONS FOR STOVING LACQUERS AND A PROCESS FOR THE PRODUCTION OF COATINGS THEREFROM

摘要

The present invention relates to a binder composition containing a) 20 to 70% by weight of oligomerization products of 1,6-diisocyanatohexane, the oligomerization products having isocyanate groups at least partially blocked with blocking agents for isocyanate groups and containing at least 50% by weight, based on the weight of the oligomerization products, of blocked uretdione diisocyanates corresponding to formula (I) (see formula I) wherein R represents the residue formed by removal of the active hydrogen atom from a monofunctional blocking agent, and b) 30 to 80% by weight of a polyol component containing a mixture of b1) 100 parts by weight of an alkoxylation product of bisphenol A corresponding to formula (II) whereinR' is hydrogen or a methyl group and n is a whole or fractional number from 1 to 2, b2) 20 to 200 parts by weight castor oil and b3) 0 to 40 parts by weight of other organic polyhydroxyl compounds. The present invention also relates to a process for the production of coatings by coating heat-resistant substrates with a heat-curing coating composition containing the binder compositions of the present invention and subsequently curing the coatings at 90 to 220.degree.C.