Transparent abrasion-resistant coating for a styrene acrylonitrile copolymer and method

A method of forming a clear, abrasion-resistant coating film on a styrene-acrylonitrile copolymer resin base layer comprising:

• a. treating a surface of said base layer with a strong oxidizing solution consisting essentially of a strong alkali metal dichromate, a strong mineral acid and water,
• b. applying a coating solution to said activated surface of said base layer, said coating solution comprising by weight,
• 1. 1 to 10 parts partially hydrolyzed poly(vinyl acetate), and
• 2. 20 to 40 parts water, and
• 3. 20 to 40 parts of a solvent selected from the group consisting of alkyl alcohols having up to 7 carbon atoms, and alkyl carboxylic acids having up to 7 carbon atoms, and
• 4.

10 to 50 parts of tetraethyl orthosilicate, said silicate being previously equilibrated in the presence of water, and

• 5. from 1/2 part to 15 parts of silane compound selected from the group consisting of those compounds described by the general formula:
• ##EQU7## where x is from 1 to 10 and those compounds described by the general formula:
• ##EQU8## where x is from 1 to 10 and y is from 1 to 10, with said trimethoxy functionality of said silane being initially hydrolyzed in said solution, and
• c. baking said treated and coated base layer to form a dried coating consisting essentially of the crosslinked condensation product of said equilibrated tetraethyl orthosilicate, said partially hydrolyzed
• poly(vinyl acetate), and said hydrolyzed silane compound. 4. A method of forming a clear, abrasion-resistant coating film on a styrene-acrylonitrile copolymer resin base layer comprising:
• a. treating a surface of said base layer with an oxidizing agent to chemically activate said surface,
• b. applying a coating solution to said chemically activated surface of said base layer, said coating solution comprising, by weight,
• 1. 1 to 10 parts of partially hydrolyzed poly(vinyl acetate), and
• 2. 20 to 40 parts water, and
• 3. 20 to 40 parts of a solvent selected from the group consisting of alkyl alcohols having up to 7 carbon atoms, and alkyl carboxylic acids having up to 7 carbon atoms, and
• 4. 10 to 50 parts of tetraethyl orthosilicate, said silicate being previously equilibrated in the presence of water, and
• 5. 1/2 part to 15 parts of an adhesion promoting agent selected from the group consisting of a compound described by the general formula:
• ##EQU9## where x is from 1 to 10 and compounds with the general formula:
• ##EQU10## where x is from 1 to 10 and y is from 1 to 10, c. baking said treated and coated base layer to dry said coating and to form the crosslinked condensation product of said equilibrated tetraethyl orthosilicate, said hydrolyzed poly(vinyl acetate), and said hydrolyzed silane compound and to form an integral bond by means of said adhesion promoting agent with said chemically activated surface.

A method of forming a clear, abrasion-resistant coating film bonded onto a styrene-acrylonitrile copolymer resin base layer comprising:

• a. treating a surface of said base layer with an oxidizing agent to chemically activate said surface,
• b. applying to and wetting said activated base layer with a primer solution comprising an adhesion promoting primer selected from a group consisting of compounds with the general formula:
• ##EQU11## where x is from 1 to 10 and compounds with the general formula:
• ##EQU12## where x is from 1 to 10 and y is from 1 to 10;
• c. baking said base layer to dry said primer,
• d. applying a coating solution to said base layer comprising, by weight, from
• 1. 1 to 10 parts of partially hydrolyzed poly(vinyl acetate), and
• 2. 20 to 40 parts water, and
• 3. 20 to 40 parts of a solvent selected from the group consisting of alkyl alcohols having up to 7 carbon atoms, and alkyl carboxylic acids having up to 7 carbon atoms, and
• 4. 10 to 50 parts of tetraethyl orthosilicate, said silicate being previously equilibrated in the presence of water, and
• e. baking said treated and coated base layer to form a dry crosslinked condensation coating product of said equilibrated tetraethyl orthosilicate, said hydrolyzed poly(vinyl acetate), and said hydrolyzed silane of said primer.