Low-shrink in-mold coating

Claim 1

A thermosetting composition comprising essentially: (a) an unsaturated aliphatic polyester fumarate diol having an average molecular weight of from about 1,500 to 4,500 and from about 8 to 30 internal aliphatic carbon-to-carbon double bonds, (b) a saturated aliphatic polyester diol flexibilizer having an average molecular weight of from about 1,500 to 3,000, (b) being present in a minor molar amount as compared to (a), (c) an aliphatic crosslinking polyol having from 3 to 6 hydroxyl groups and an average molecular weight of from about 92 to 1,000, (d) a diisocyanate selected from the group consisting of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenyl methane diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, polymeric forms of TDI, MDI and hydrogenated MDI, xylene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate and mixtures thereof, said diisocyanate being present in an amount by weight sufficient to provide from about 50 to 120% of the stoichiometric amount of --NCO groups required to react with all of the active hydrogen atoms in said composition, and (e) an ethylenically unsaturated monomer selected from the group consisting of styrene, alpha methyl styrene, vinyl toluene, methyl methacrylate, acrylamide, acrylonitrile, methyl acrylate and mixtures thereof, said monomer being present in an amount sufficient to copolymerize with and crosslink said unsaturated polyester, in admixture with (f) from about 2 to 20 parts by weight of polyvinyl acetate per 100 parts by weight of said total composition.