CURABLE POWDER FILM-FORMING COMPOSITION HAVING CHEMICAL RESISTANCE

摘要

A curable powder film-forming composition is provided. The composition comprises a solid, particulate mixture of the following ingredients: (a) 60 to 70 percent by weight based on the total weight of resin solids in the film-forming composition, of an epoxy functional copolymer having a Tg of 77 DEG F to 158 DEG F (25 DEG C to 70 DEG C) formed by polymerizing under free radical initiated polymerization conditions: (i) 25 to 75 percent by weight based on the total weight of (i) and (ii) of a glycidyl functional ethylenically unsaturated monomer, and (ii) 25 to 75 percent by weight based on the total weight of (i) and (ii) of a copolymerizable ethylenically unsaturated monomer or mixture of monomers free of glycidyl functionality; (b) 15 to 30 percent by weight based on the total weight of resin solids in the film-forming composition, of a polycarboxylic acid crosslinking agent having a Tg of 77 DEG F to 158 DEG F (25 DEG C to 70 DEG C); and (c) 1.0 to 5.0 percent by weight based on the total weight of resin solids in the film-forming composition, of a polyisocyanate at least partially capped with a capping agent and having a Tg of 77 DEG F to 158 DEG F (25 DEG C to 70 DEG C). Also provided is a multi-component composite coating composition comprising a base coat deposited from a pigmented film-forming composition and a transparent top coat applied over the base coat wherein the transparent top coat is deposited from a clear film-forming composition and is the curable powder film-forming composition described above.