DUAL ROLE OF A HYDROXYPHENYLBENZOTRIAZOLE UV ABSORBER IN THE PHOTO-OXIDATION OF WOOL

In the reported experimental study, the protective effect of the UV absorber, sodium 2-(2 prime -hydroxy-5 prime -methylphenyl)benzotriazole sulfonate, on the light stability of wool has been examined. The degree of protection, as measured by the reduction in the rate of photoyellowing of the fiber, is highly dependent on both the spectral composition of the light source and pH at which the absorber is applied to the fiber. This is due mainly to traces of the deprotonated, phosphorescent form of the absorber which can sensitize the photooxidation of wool in visibile light, hence counteracting the photostabilizing influence of the UV absorber.