Modified aminoplast crosslinkers and powder coating compositions containing such crosslinkers

摘要

A crosslinking agent is provided which is an ungelled reaction product of (a) an aminoplast resin and (b) a compound having active hydrogen groups reactive with the aminoplast resin (a) such that the crosslinking agent is essentially free of functional groups reactive with aminoplast resin and has a glass transition temperature of at least 10° C. Also provided is a method for preparing the crosslinking agent. Further provided is a curable powder coating composition including (A) a polymer having a glass transition temperature of at least 30° C. containing reactive functional groups and (B) the previously described crosslinking agent. Additionally provided is a multilayer composite coating composition including a base coat deposited from a film-forming composition and a top coat over the base coat deposited from the previously described powder coating composition. Coated substrates are also provided.