Coated plastic substrates for coating compositions

Abstract

There is provided a coating process, and compositions for practicing the process, wherein organic polymeric substrates, and especially polycarbonates and acrylics, are coated with a coating composition which is curable in a short period of time to provide the substrate with a hard, abrasion-resistant, mar-resistant, chemical resistant and acetone-resistant, strongly adhered coating. The coating composition employs the use of effective cure promoting amounts of a methanol and lower alkyl alcohol-melamine-formaldehyde partial condensate reaction products which are added to organopolysiloxanes made from methyltrialkoxysilane, wherein the organopolysiloxanes are made by a prescribed technique; the alkoxy groups contain one to six carbon atoms and the alkyl alcohol is a C.sub.2 to C.sub.4 alkyl alcohol or mixtures thereof. Most desirably, the organopolysiloxane is made from methyltriethoxysilane and the alkyl alcohol-melamine-formaldehyde partial condensate reaction product is an isobutylated and methylated melamine-formaldehyde. Clear, solid polycarbonate substrates are especially advantageously coated as provided herein to provide a coating with the above features and one which has good optical clarity.