POWDER COATING COMPOSITIONS AND COATED SUBSTRATES WITH MULTILAYERED COATINGS

摘要

Curable powder clear coating composition and coated substrate with multilayered coatings have as the predominant film-forming polymer in the coating at least one epoxy acrylic copolymer in an amount from 60 to 99.99 percent by weight and 10 to 40 percent by weight of a polycarboxylic acid crosslinking agent. The percentages by weight are based on solids of the curable coating composition. A single predominant film-forming epoxy acrylic copolymer has a number average molecular weight in the range of about 1000 to 5500; a calculated Tg in the range of 50 to 85 DEG C; epoxy content in the range of 35 to 85, and a styrene content resulting from an amount of styrene monomer in the range of up to about 25 weight percent based on the weight percent of the monomers to form the copolymer. The blend of epoxy acrylic copolymer has one polymer which is the single epoxy acrylic copolymer or one having a number average molecular weight in the range of about 1000 to about 10,000, a calculated Tg in the range of about 40 DEG C to 85 DEG C, and an epoxy content from 40 to 60 weight percent of the total weight of the monomers to prepare the epoxy acrylic copolymer. The other polymer of the blend has a number average molecular weight in the range of about 500 to about 3000, a calculated Tg in the range of about 35 DEG C to about 125 DEG C, and an epoxy content from glycidyl functional ethylenically unsaturated monomer that is higher than that of the first epoxy functional acrylic copolymer of the blend and in the range of about 50 to about 100.