Patent ID: 7431789

Claim:
A process for forming a molded plastic substrate comprising: providing a mold; providing an epoxy matrix resin base comprising an amine component; providing a gelcoat composition comprising: a base resin comprising an ethylenically unsaturated matrix; and a reactive diluent consisting of one or more functional monomers selected from Formula I, ethoxylated trimethylpropane triacrylate, or trimethylpropane trimethacrylate; wherein: R is a 5 to 10 carbon atom containing mono- or dicyclic alkyl or alkenyl ester radical having one or more optional alkyl substituents of 1 to 3 carbon atoms, and R′ is H or CH 3 ; applying a layer of the gel coat composition to the mold; allowing the gel coat composition to partially cure until it is tacky; and applying the epoxy matrix resin base over the partially-cured gel coat composition, wherein a Michael addition of the acrylate or methacrylate ester component of Formula I and the amine component of the epoxy matrix results in a plurality of amine-acrylate adducts that in turn react with the epoxy matrix resin base to achieve a covalent bond between the epoxy matrix resin base and the gel coat composition, wherein the gel coat provides mechanical and physical performance comparable to conventional gel coats, thereby forming a molded plastic substrate.