Polycarbonate article coated with an adherent, durable, silica filled organopolysiloxane coating and process for producing same

A process for producing a mar, abrasion, scratch and chemical solvent resistant polycarbonate article comprising the steps of:

• (i) applying onto the polycarbonate an ultraviolet radiation curable primer composition containing (a) at least one polyfunctional acrylic acid ester monomer, (b) at least one organic silicon compound containing at least one organic group having olefinic unsaturation, (c) resorcinol monobenzoate, alkyl substituted resorcinol monobenzoate, or mixtures thereof, and (d) a photo-initiator;
• (ii) curing said primer composition by exposure to ultraviolet radiation to form a cured primer layer;
• (iii) applying onto said cured primer layer a silica filled further curable organopolysiloxane top coat composition comprising a dispersion of colloidal silica in a lower aliphatic-water solution of the partial condensate of a silanol of the formula R.sup.6 Si(OH).sub.3 wherein R.sup.6 is 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 gamma-glycidoxypropyl radical and the gamma-methacryloxypropyl radical, at least 70 weight percent of said silanol being CH.sub.3 Si(OH).sub.3, said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0;
• (iv) evaporating the volatile solvents from said composition;
• and,
• (v) applying heat to said composition to cure said composition, whereby said silanol is condensed further to a silsesquioxane.

A polycarbonate article having improved scratch, mar, abrasion and chemical solvent resistance comprising a polycarbonate substrate having thereon (i) an ultraviolet radiation cured primer layer, said cured primer layer being the photoreaction product of a primer composition containing at least one polyfunctional acrylic acid ester monomer;

• at least one organic silicone compound containing at least one organic group having olefinic unsaturation and represented by the general formula R.sup.4.sub.c SiX.sub.4-c wherein X represents an alkoxy, acyloxy or aryloxy radical, R.sup.4 represent a compound represented by the formula
• CH.sub.2 .dbd.CYCOO--R.sup.5 --,
• and ##STR49## wherein Y is hydrogen or methyl and R.sup.5 is a divalent saturated aliphatic hydrocarbon radical, and c is an integer from 1 to 3, a photoinitiator, and a compound selected from resorcinol monobenzoate, lower alkyl substituted resorcinol monobenzoate, or mixtures thereof;
• and, (ii) a cured colloidal silica filled thermoset organopolysiloxane top coat on said cured primer layer, said top coat being the thermally cured product of a top coat composition comprising a dispersion of colloidal silica in a lower aliphatic alcohol-water solution of the partial condensate of a silanol of the formula R.sup.6 Si(OH).sub.3 wherein R.sup.6 is selected from the group consisting of alkyl radicals containing 1 to 3 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.sub.3 Si(OH).sub.3, said composition containing sufficient acid to provide a pH in the range of 3.0 to 6.0.