PURPOSE: To provide a thermal recording medium high in whiteness, excellent in high-speed recording ability and free from reduction in recording ability or density even when fingerprints are adhered, wherein a plurality of respectively specified fluoran base dyes are used as basic dyes in combination with an organic color reaction agent.
CONSTITUTION: In a thermal recording medium utilizing a color reaction between a colorless or light-colored basic dye and an organic color reaction agent capable of forming a color by contacting the dye, a dye of formula I (wherein R1 is methyl, ethyl; R2 is 5W8C alkyl) [preferably, 3-(N-ethyl-N-isoamyl)amino- 6-methyl-7-anilinofluoran] and a dye of formula II and/or III (wherein each of R3, R4 is methyl, ethyl, tolyl or the like; each of R5, R6 is 1W4C alkyl; X is H, 1W4C alkyl or the like; m is 1W2; Y is colorine, trifluoromethyl) having a glass transtition temperature of 80°C or above, preferably 100°C or above (preferably, 3-pyrrolidino-6-methyl-7-anilinofluoran) are jointly used as the dye.
SUZUKI TOSHITAKE
ARAI NAOTO
OEDA YOSHITAKA
