Enhancing weathering resistance of UV-curable coatings by using TiO2 particles as filler

Abstract

Aiming to enhance the weathering resistance of UV curable coatings, this study prepared a series of UV-curable composite coatings using TiO2 particles as filler and systematically evaluated the influences of TiO2 on the UV-curing process and weathering performance. The effect of TiO2 on the curing process of the UV-cured coating was assessed by double bond conversion rate, gel content test and curing depth. The weathering resistance of the UV-cured coating was evaluated by color and gloss change, FTIR spectroscopy, SEM images as well as anticorrosion property through artificial accelerated UV aging test. The results showed that the presence of TiO2 has a negative effect on the curing efficiency, but by properly tuning the TiO2 content and coating thickness, a fully UV-cured coating with high double bond conversion and gel content could still be prepared. During accelerated UV aging test, the UV-cured TiO2 composite coating exhibited a much smaller change in color, gloss, morphology, and surface chemistry than pristine coatings, demonstrating the presence of TiO2 could remarkably enhance the weathering resistance of UV curable coatings. Salt spray test shows better anti-corrosion behavior of the aged composite coating compared to aged pure resin coating.