Silicone(polysiloxane) hard coatings are finishes of superior abrasion resistance to environmental conditions. The unique character of newly developed silane-silica coating polymer provides an optically clear hard coating for use on clear plastic and numerous other substrates. They consist of several monomers and other ingredient. Among the highly varied components are monomeric silanes, hydrolyzed silanes, silica sols and catalysts of various types. Silicone coatings are solvent borne coatings. Some of the possible solvents are alcohols and glycol ether.
One of the most promising and widely used transparent plastics for glazing is polycarbonate(PC). Attempts have been made to improve the abrasion resistance of polycarbonate. Abrasion resistant coatings(ARC) are formed from mixtures of silica, such as colloidal silica, and hydrolyzable silanes in a hydrolysis medium, such as alcohol. The coating compositions used in this paper were prepared by hydrolyzing the methyltrimethoxysilane in aqueous dispersion of colloidal silica, diluting the solids contents of the resultant hydrolysis mixture with solvents comprising alcohols. Methyltrimethoxysilane and tetraethoxysilane were also used to prepare ARC. Various amounts of colloidal silica were added to the ARC solution and different pHs of ARC were prepared.
The coatings were cured thermally in the baking conditions that vary according to the heat stability of the substrates. The cure time of ARC for PC varies from 5 minutes to 7 hours. Since this is solvent-borne coating.
In this study, abrasion resistances of the different coatings were checked. Light transmittance and adhesion were also examined.
Abrasion resistant coatings have become important in many industries. Their tremendous hardness and excellent properties make them candidates for expansion into other areas of use.
