Photostabilization of organic thermochromic pigments. Part 2: Effect of hydroxyarylbenzotriazoles containing 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; improvement of light fastness is therefore being sought. Various kinds of stabilizer were synthesized in an attempt 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 hydroxyarylbenzotriazoles bearing groups that are capable of acting as amphoteric counter-ions play an important role in improving the light fastness of colorants for imaging and data-recording systems. Both zinc and nickel 3-(2-benzotriazolyl)-2-hydroxy-1-naphthoates and derivatives are proposed as effective stabilizers against the fading of color formers.