| 摘要 |
PROBLEM TO BE SOLVED: To uniformly erase at a lower temperature of a wider temperature range with respect to an erasing temperature with lower image density and small erasing residue at the time of color erasing by using a certain specific indolylphthalide compound. SOLUTION: An indolylphthalide compound represented by a formula (wherein R<1> is a dual substitution amino group or the dual substituents may be coupled to each other to form a ring, R<2> is a hydrogen atom, alkoxy group alkyl group, acryloxy group, aryl oxy group, hydroxyl group or halogen atom, R<3> is an alkyl group, R<4> is an alkyl group or aryl group, R<5> is a hydrogen atom, alkyl group, alkoxy group or halogen atom.) is a dye precursor having an excellent whiteness degree after erasing. In this case, it is preferable to use it by mixing it with an indolylazaphthalide compound by considering a print image density, heat resistant preservability and light resistant stability of the print image. |
