High-solids thermosetting enamel coating composition

Claim 1

A thermosetting enamel coating composition of a mixture of a polymer blend and a solvent for the polymer blend wherein the blend is 65-90% by weight of the mixture and consists essentially of (a) 5-25% by weight, based on the weight of the blend, of a copolymer of (1) a hydroxyalkyl ester of acrylic or methacrylic acid wherein the alkyl group has 2-10 carbon atoms and wherein the hydroxyalkyl ester is 25-35% by weight of the copolymer, and (2) at least one other ethylenically unsaturated monomer selected from the group consisting of vinyl chloride, vinylidene chloride, ethylene, propylene, vinyl acetate, conjugated dienes, styrene, alkyl-substituted styrene, dibutyl maleate, C 1 -C 12 alkyl esters of acrylic acid, C 1 -C 12 alkyl esters of methacrylic acid, and mixtures of these wherein the copolymer has a hydroxyl content of 2-6% by weight; (b) 40-60% by weight, based on the weight of the blend, of a saturated polyester polyol that is the reaction product of (1) pentaerythritol and at least one other branched-chain glycol wherein the molar ratio of glycol to pentaerythritol is from 2:1 to 6:1, (2) and aromatic or saturated aliphatic monocarboxylic acid having no more than 18 carbon atoms, and (3) a mixture of an aromatic and a saturated aliphatic acid wherein the molar ratio of aromatic acid to aliphatic acid is from 2:1 to 6:1 wherein the polyol has a hydroxyl content of 5-9% by weight; and (c) 25-45% by weight, based on the weight of the blend, of an aminoplast resin.