| 摘要 |
PROBLEM TO BE SOLVED: To ensure sufficient preservability of an image by incorporating composite fine particles made of specific dye precursor and specific developer in a thermal recording layer on a support, thereby forming a color developing image on a white surface and incorporating high contrast. SOLUTION: A thermal recording layer containing dye precursor and developer for reversely color developing and erasing on a sheet-like support is formed in the recording medium. The precursor is contained in a form of composite fine particles manufactured by emulsifying and dispersing solution containing the precursor as solute and polyhydric isocyanate as solvent in hydrophilic protective colloidal solution and then expediting polymerization reaction. And, as the developer, at least one type of aromatic compound represented by a formula I is contained, where R1 indicates one member selected from naphthyl group or hydrogen atom, halogen atom, lower alkyl group and phenyl group substituted by lower alkoxy group, Y1 indicates one member selected from bivalent groups represented by a formula II, and n indicates an integer of 11 to 30. |
