Coating lacquers for plastics articles.

摘要

Lacquers for coating plastics articles (such as lenses and visors) to improve their abrasion and chemical resistance, are made by a method which comprises: a) forming a mixture comprising: i) one or more silicon-containing compounds selected from tetra (C1-C3)alkylorthosilicates, (C1-C3)alkyltri (C1-C3)alkoxysilanes and aryltri (C1-C3) alkoxysilanes; ii) a strong acid condensing agent for (i); and iii) a solvent comprising one or more alkanols; b) allowing the mixture to age; c) adding to the aged mixture: i) a weak organic acid; and ii) an abrasion resistance enhancer if the same was not added in step (a); d) allowing the mixture from step (c) to age until its viscosity reaches the desired value; and e) immediately adding to the aged mixture from step (d) a further quantity of a weak organic acid to stabilise the viscosity at the desired level; and wherein one or more complex ether wetting agents are optionally also included in the reaction mixture.