| 摘要 |
PURPOSE:To provide a color forming sensitivity sufficient for application to practical and wide use and make it possible to cope with a high degree of quality requirements with high brightness, by using a specified dihydroxydiphenyl ether as a color developer. CONSTITUTION:A thermal color forming layer comprises a dihydroxydiphenyl ether of the formula together with at least one colorless or light-colored basic dye. The ether may be, for example, 2,2'-dihydroxydiphenyl ether (m.p. 121 deg.C), 3,3'-dihydroxydiphenyl ether (m.p. 98 deg.C) or 4,4'-dihydroxydiphenyl ether (m.p. 166 deg.C). The amount of the ether is generally 0.5-3 pts.wt., preferably, 1-2 pts.wt. per 1 pts.wt. of the basic dye. The colorless or light-colored basic dye to be used with the dihydroxydiphenyl ether color developer may be any of those which are ordinarily used for this purpose. |
