Photostabilization of organic thermochromic pigments: Action of benzotriazole type UV absorbers bearing an amphoteric counter-ion moiety on the light fastness of color formers

Color formers are extensively used in information recording systems or thermochromic systems for textiles, but their light fastness properties are poor. The improvement of light fastness is therefore being sought at the present time. Various kinds of stabilizers have been synthesized to prolong the life of colored species derived from color formers. The retarding effect of these compounds towards photofading was investigated on cellulose. It was found that the UV absorbers bearing the groups capable of acting as an amphoteric counter-ion play a very important role in improving the light fastness of colorants for imaging and data recording systems. Zinc and nickel 5-(2-benzotriazolyl)-2,4-dihydroxybenzoates and the derivatives have been proposed as effective stabilizers against the fading of color formers.