Polycarbonate has been used extensively in the automotive industry as a replacement to glass components. Sun roofs, windows, and lens covers are the primary components presently being made of polycarbonate. However, polycarbonate is susceptible to scratching and degradation from UV light. Hence, there is a need for developing a highly transparent protective coating for both scratch resistance and UV light absorption.
A lacquer based coating can be sprayed on polycarbonate and then thermally cured to provide a hard coating that also blocks UV light. Such a coating is typically in the range of 2-10 μm thick. The cost associated with this lacquer based technology is so high that it limits applications.
Another coating method is to first form a soft UV blocking layer benzyl phenon on a polycarbonate substrate. Next, a hard organo-silicon coating can be formed on the coated polycarbonate substrate by using plasma enhanced chemical vapor deposition (PECVD). The two-layer coating is normally 2-10 μm thick. Such an organo-silicon coating provides a much harder coating than the lacquer based system. However, the UV blocking layer beneath the organo-silicon coating is degraded from UV light attack over time. As a result of consumption of UV absorbers, the organo-silicon coating will typically shrink or crack after about 3000 to 5000 hours, which will shorten the lifetime of the scratch resistance coating. Therefore, there is a remaining need in the art to provide methods and systems for developing an endurable and transparent protective coating for UV blocking and scratch resistance.