| 摘要 |
PURPOSE:To obtain the title recording medium with the white paper part which does not discolor, if preserved for a long time at high temperatures or high humidity, and make possible the maintenance of a stably recorded image of bluish black or blackish blue by adding at least one type of specific fluoran derivative and at least one type of phthalide derivative as basic dyes and also using a specific coloring agent. CONSTITUTION:A heat-sensitive recording medium consists of a heat-sensitive layer containing a colorless or pale-color basic dye and a coloring agent which forms a color through contact with said dye provided on a support. This medium contains at least one type of fluoran derivative expressed by formula I as a basic dye and at least one type of phthalide derivative expressed by formula II. The amount of the phthalide derivative is equivalent 1-20% by weight, compared to the amount of the fluoran derivative. In addition, 4-hydxroxy-4'- isopropoxydiphenylsulphone is used as a coloring agent. In the formula, R1-R2 are groups substituted by alkyl groups, unsaturated alkyl groups and alicyclic groups. R3-R4 are hydrogen atoms, alkyl groups atoms and X is a hydrogen atom, an alkyl group or a halogen atom. n1-4 are integers. R5-R10 are hydrogen atoms, alkyl groups, unsaturated alkyl groups and alicyclic groups. |
