A well known problem with compression molded articles is that the surfaces thereof are aesthetically undesirable because of defects such as pits, porosity, sink marks and micro cracks. Various in-mold coating compositions have been developed to coat and cover surface defects of compression molded articles to provide a smooth high quality surface having an aesthetically appealing appearance. One part thermosetting in-mold coating compositions, which cure upon exposure to elevated temperatures, are preferred. Examples of such compositions generally include blocked polyisocyanates which react with a polyol upon unblocking of the isocyanate groups, unsaturated polyesters and vinyl ester resins which react with an ethylenically unsaturated monomer, such as styrene, via free radically initiated addition polymerization, polyurethane precursors having terminal ethylenically unsaturated sites which react with an ethylenically unsaturated addition monomer, and the like.
USPTO Backgrounds
USPTO Backgrounds