Synthesis of benzotriazole UV absorbers with blocked hydroxy group and their application to UV curable paint

In order to realize ideal UV absorbers which do not disturb UV curing proce sses and yet can act as a absorber, the hydroxy group of 2-(2H-benzotriazol -2-yl) phenol was blocked with a diphenylphosphinyl group and the propertie s of the resulting blacked benzotriazole derivative were examined. The results indicated that the triazole showed almost no negative effect on the UV curing processes, but improved the weatherability of the cured pain ts. Spectroscopic studies were carried out in order to reveal the origin of the present observations, which suggested that strong emission from the benzot riazole played an important role.