Abrasion-resistant lenses and process of making

Claim 1

In combination, an ophthalmic lens selected from the group consisting of polycarbonate and poly diethyleneglycol bis allyl carbonate lenses; a tie-coating having the formula AR 1 Si(OR 2 ) a (R 3 ) b (OH) c wherein A is NH 2 , NHR 2 or NHR 1 NH 2 when the lens is a polycarbonate and is ##STR2## when the lens is a polydiethyleneglycol bis allyl carbonate, R 1 is an alkylene having 2 to 10 carbons, R 2 and R 3 are alkyl having 1 to 4 carbons, a is 0, 1 or 2, b is 0, 1 or 2, c is 1, 2 or 3 and a+b+c=3; the tie-coating being reacted through A with the lens; and an abrasion-resistant coating from immersion of the lens with the tie-coating in a pigment free aqueous coating composition comprising a dispersion of colloidal silica in lower aliphatic alcohol-water solution of the partial condensate of a silanol of the formula RSi(OH) 3 in which R is selected from the group consisting of alkyl radicals of 1 to 3 inclusive carbon atoms, the vinyl radical, the 3,3,3-trifluoropropyl radical, the gamma-glycidoxypropyl radical and the gamma-methacryloxypropyl radical, at least 70 weight percent of the silanol being CH 3 Si(OH) 3 , said composition containing 10 to 50 weight percent solids consisting essentially of 10 to 70 weight percent colloidal silica and 30 to 90 weight percent of the partial condensate, the abrasion-resistant coating being reacted with the OH of the tie-coating.