DYE FOR LIGHT-DECOLORIZABLE MATERIAL, LIGHT-DECOLORIZABLE RESIN COMPOSITION, LIGHT-DECOLORIZABLE INK, LABEL FOR INDICATING ULTRAVIOLET EXPOSURE, AND OPTICALLY RECORDING MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain a light-decolorizable resin composition improved in decolorizability and storability by including a dye for a light-decolorizable material with a binder resin. SOLUTION: A light-decolorizable resin composition is obtained by dissolving in a binder resin 0.1-20 wt.%, particularly, 1-10 wt.% at least one colorant for a light-decolorizable material, selected from colorants represented by formulae I to IV, obtained by reacting a coupler with an aldehyde-substituted aromatic derivative and having a molecular weight of 340-1,200, particularly, 560-900, and optionally dissolved in a solvent. This composition is applied to a 1-100 m thick support and dried to obtain an ultraviolet exposure indication material having a percentage density change of 3-15%/8 hr upon being illuminated with light from a white-light fluorescent lamp at 60 Lux at 10 deg.C. In the formulae, Z and Z' are each an atomic group necessary to form a five-membered aromatic-heterocyclic ring; R and R' are each a group capable of being introduced into the aromatic-heterocyclic ring as a substituent; m and n are each 0-3; Cp is a group which is bonded to the aromatic-heterocyclic ring through methylene to form a chromophore together; R1 and R2 are each H, a halogen, or a substituent; and X is O or S.