BENZOTRIAZOLE STABILIZERS - STRUCTURE ELUCIDATION OF PHOTOLYTIC DISCOLORATION PRODUCTS BY MASS-SPECTROMETRY

Identification of the causes of discoloration of commercial and polymers caused by low levels of intensely chromophoric impurities or degradation products is a recurrent analytical problem in industrial laboratories. The authors report here that the discoloring components were identified as two different 2-(2'-hydroxy-5-alkylphenyl)benzoatriazoles. These substituted benzotriazoles are additives used as ultraviolet light absorbers to stabilize plastics against discoloration and deterioration. It has been published that the benzotriazole stabilizers are attacked by peroxy radicals to form stable adducts. The discoloration reported here is dependent on exposure to light and to contaminants in the air.