To prevent the discoloration of ground color by adding a UV ray absorption agent in an undercoating layer and/or thermal recording layer, a UV ray interruption agent in the thermal recording layer and/or protection layer, a fluorescent dye in the protection layer, and a specific compound as a developer in a thermal coloring layer.
As a developer in a thermal coloring layer, at least one kind of a compound expressed by formula I or II is contained. Herein, in the formulas, A shows a 1-4C alkyl group, a 1-4C alkoxy group, a hydroxy group, and a nitro group. Also, in the formulas, R1, R2, R3 show each a hydrogen atom, a 1-4C alkoxy group, a hydroxy group, and a nitro group. Furthermore, in the formulas, R1, R2, R3 each indicate a hydrogen atom, a 1-4C alkoxy group of, a hydroxy group, and nitro group. R1 and R2 can combine with each other to form an aromatic ring. Y is a sulfur atom or oxygen atom. In addition, in the formulas, B denotes hydrogen, a 1-4C alkyl group, a 1-4C alkoxy group, a hydroxy group, and a nitro group.
NAGAI TOMOAKI
HAMADA KAORU
WAKITA YUTAKA
