| 摘要 |
PURPOSE:To enable read-out through a reader employing a light source of a semiconductor laser or an LED and to improve the sensibility, by employing a specific coloring matter having light absorption in near infrared long wavelength region. CONSTITUTION:In a thermal recording material utilizing coloring reaction between leuco dye and developer for coloring said leuco dye upon contact, a compound shown by formula (I) is employed as the leuco dye while a compound shown by formula (II) is employed as the developer. Since special leuco dye shown by formula (I) is employed, a coloring image thus produced has absorption in near infrared region, whereby it can be read out by means of an image reader employing such light source as a general use semiconductor laser or an LED. Since a compound shown by formula (II), preferably shown by formula (III) is employed as a developer in combination with leuco dye, thermal energy necessary for coloring reaction can be reduced while the thermal sensibility is improved and the stability of image can be improved. In the formula, R1-R4 represent hydrogen or alkyl group, R5, R6 represent hydrogen or phenyl group and R7 represents alkyl group or phenyl group. X1-X4 represent hydrogen, halogen or alkyl group, Y represents halogen, hydroxyl group, phenoxy group or benzyloxy group and Z1-Z4 represent hydrogen or alkyl group. |
