I. Description of the Prior Art
Thermoplastic and thermoset polymers can be improved as to abrasion resistance by siloxane- and silicone-based abrasion resistant coatings such as those disclosed in U.S. Pat. No. 3,986,997 to Clark, U.S. Pat. No. 3,894,881 to Suzuki et al, or U.S. Pat. No. 4,159,206.
However, such coating compositions, when applied directly to polycarbonate substrates, do not adhere adequately.
Japanese Patent Application No. 81928/73 published Nov. 1, 1973 and assigned to Toray Industries, Inc. teaches the advantage of a primer coating whose binder is a polymer of methyl methacrylate prior to applying a siloxane abrasion resistant coating, but in all cases when polymers of methyl methacrylate are used in the tie coating, the tie coating was baked on prior to applying the abrasion resistant coating.
The object of my invention is to provide a primer coating system which improves the adhesion of silicone- and siloxane-type abrasion resistant coatings to thermoplastic and thermoset substrates.
Another object is to provide a method of improving the adhesion of such coatings to such substrates.
A further object is to provide substrates having a first primer coating and a second abrasion resistant coating.
USPTO Backgrounds
USPTO Backgrounds