| 摘要 |
PURPOSE:To provide a thermal recording material which has good coloring property, good green keeping property, and the stability of a coloring image, efficient in the chemical resistance of a recording material, and of which the absorption wavelength of the coloring image is at near infrared part, by provid ing fluorene compound having substituent amino as electron donor achromatic dye and a compound having a acid group of which the solubility to ethanol at 25 deg.C is not more than 2. CONSTITUTION:Fluoran derivative expressed by Formula 1 is preferable among fluorene derivatives. R1, R2, R3, R4, R5, and R6 in the formula represent alkyl groups which may have respectively substituents of 1-10 in number of carbon atoms. Though there are many electron acceptor compounds having acid group, the solubility to ethanol at 25 deg.C above all when zinc salt is derived therefrom, is preferably not more than 0.5 and especially preferably not more than 0.1. Salicilate derivative expressed by Formula 2 is preferable among electron accepting compounds. In the formula above-mentioned, R represents alkyl group, alkoxy group, acyl group, acylamino group, or aryl group and X represents hydrogen atom, alkyl group, alkoxy group, or halogen atom. |
