Method for coating a polycarbonate article with silica filled organopolysiloxane

Claim 1

A method for producing a polycarbonate article having improved mar, abrasion, scratch and chemical solvent resistance comprising: (i) applying onto a polycarbonate substrate a primer emulsion composition containing, in percent by weight, (a) from about 1 to about 10 percent of a thermosettable acrylic polymer, (b) from about 20 to about 45% of a hydroxy ether, and (c) from about 45 to about 79 percent of water; (ii) evaporating off a substantial portion of said water and hydroxy ether from said primer emulsion composition to form a thin layer comprised of thermosettable acrylic; (iii) thermally curing said thermosettable acrylic to form a thermoset acrylic primer layer; (iv) applying onto said cured primer layer a silica filled further curable organopolysiloxane top coat composition comprising a dispersion of colloidal silica in a lower alkanol-water solution of the partial condensate of a silanol of the formula RSi(OH) 3 wherein R is a radical selected from the group consisting of an alkyl radical containing 1 to 3 carbon atoms, the vinyl radical, the 3,3,3-trifluoropropyl radical, the gammaglycid oxypropyl radical and the gamma-methacryloxpropyl radical, at least 70 weight percent of said silanol being CH 3 Si(OH) 3 , said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0; (v) evaporating off a substantial portion of the volatile solvents from said top coat composition thereby forming a layer comprised of a silica filled partial condensate of said silanol; and, (iv) thermally curing said silica filled partial condensate of said silanol.

Claim 2

A method for producing a polycarbonate article having improved mar, abrasion, scratch and chemical solvent resistance comprising: (i) applying onto a polycarbonate substrate a primer emulsion composition containing, in percent by weight, (a) from about 1 to about 10 percent of a thermosettable acrylic polymer, (b) from about 20 to about 45% of a hydroxy ether, and (c) from about 45 to about 79 percent of water; (ii) evaporating off a substantial portion of said water and hydroxy ether from said primer emulsion composition to form a thin layer comprised of thermosettable acrylic; (iii) thermally curing said thermosettable acrylic to form a thermoset acrylic primer layer; (iv) applying onto said cured primer layer a silica filled further curable organopolysiloxane top coat composition comprising a dispersion of colloidal silica in a lower alkanol-water solution of the partial condensate of a silanol of the formula RSi(OH) 3 wherein R is a radical selected from the group consisting of an alkyl radical containing 1 to 3 carbon atoms, the vinyl radical, the 3,3,3-trifluoropropyl radical, the gammaglycid oxypropyl radical and the gamma-methacryloxpropyl radical, at least 70 weight percent of said silanol being CH 3 Si(OH) 3 , said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0; (v) evaporating off a substantial portion of the volatile solvents from said top coat composition thereby forming a layer comprised of a silica filled partial condensate of said silanol; and, (iv) thermally curing said silica filled partial condensate of said silanol.