Pigment-free coatings with improved resistance to weathering

摘要

A pigment-free coating composition comprising an acidic dispersion of colloidal titania, colloidal silica and hydroxylated silsesquioxane in an alcohol-water medium. A coating of the composition cured on a plastic substrate such as polycarbonate results in a hard, abrasion-resistant protective coating. Such coatings transmit visible light, but absorb wavelengths of ultraviolet light which cause degradation of the substrate surface and resultant adhesion-loss of the protective coating upon weathering. A cured coating of these compositions deposited on metal substrates such as aluminum results in a hard, abrasion resistant coating which offers slightly more corrosion protection than such a composition without colloidal titania.