Polysiloxane graft copolymers, flexible coating compositions comprising same and branched polysiloxane macromers for preparing same

摘要

A thermosetting coating composition adapted to form a flexible cured coating over a variety of substrates, such as metal and plastic containing a hydroxy functional urethane modified polysiloxane graft copolymer and an alkylated melamine crosslinking agent. The copolymer has a number average molecular weight between about 1,000 and about 4,000, has a hydroxyl number between about 30 and about 300, contains about 1-10 urethane linkages per molecule and is the reaction product of carbon- carbon double bond-reactive monoethylenically unsaturated monomer with hydroxy functional carbon-carbon double bond-bearing branched polysiloxane macromer. The macromer is the reaction product of glycidyl methacrylate and hydroxy functional polysiloxane reactant containing 1-10 urethane linkages per molecule.