Methods of forming UV-absorbent transparent coatings and transparent
substrates coated with the same allow for a relatively lower temperature
cross-linkage reaction between a UV-absorbent compound and an
epoxy-alkoxysilane. More specifically, UV-absorbent coatings on
transparent substrates are formed by prepolymerizing a mixture consisting
essentially of a benzophenone, an epoxy alkoxysilane and an organic
catalyst at a temperature of between about 40.degree. C. to about
130.degree. C. and for a time sufficient such that between about 30% to
about 70% of the epoxy alkoxysilane has been converted to a ring-opened
oligomer or polymer. Such prepolymerized mixture may then be hydrolyzed
and coated onto the surface of a transparent substrate, and thereafter
cured at a temperature of less than about 200.degree. C. for a time
sufficient to cross-link the hydrolyzed alkoxysilane with itself and the
glass surface. Most preferably, the prepolymerized mixture is hydrolyzed
prior to being coated onto the substrate in an acidic alcoholic solution.
Preferred for use in the present invention as a UV-absorbent compound is
tetrahydroxybenzophenone. The preferred epoxy alkoxysilane is
3-glycidoxypropyl trimethoxysilane. It is especially preferred that
prepolymerization be effected in the presence of an organic catalyst,
such as triethylamine (TEA).