| 摘要 |
A thermal recording material having both of excellent coloring property and storage stability with a low cost is provided. The thermal recording material contains a leuco dye and a developer in a coloring layer, and the developer contains 2,4'-dihydroxydiphenylsulfone and 4,4'-dihydroxydiphenylsulfone with a specific ratio, and the above-mentioned two kinds of the dihydroxydiphenylsulfones are made a material obtained by sequentially undergoing a separating step for heightening the weight ratio of a 2,4' material from a dichlorodiphenylsulfone mixture containing the 2,4' material and a 4,4' material, a reaction step of hydrolyzing the mixture to obtain a dihydroxydiphenylsulfone mixture, and a post-treatment step of subjecting to decolorization and purification. |
