| 摘要 |
PURPOSE:To improve heat resistance and to thermally laminate by incorporating specific thiourea compound in developer contained in a recording layer provided in a thermal recording medium. CONSTITUTION:A recording layer of a thermal recording medium contains as color developer at least one type of thiourea compour represented by formula (wherein X 1-6C lower alkyl group or electron attractive group, and m is an integer of 0-3). In the case of thermal recording, the compound represented by a formula contained in the recording layer in contact with a thermal head is caused by a tautomerism to become a thiol type, and a color developing function is exhibited. Then, the lactone ring of a dye precursor is cleaved, and color developed. On the other hand, the compound of the formula does not exhibit the developer function until it is changed to the chiol type structure, and not reacted with the precursor, and hence, the color developing of the ground color does not occur, and heat resistance is improved. Since the chioling temperature is higher than the thermally laminating temperature, the laminating is performed without color developing the ground color. |
