| 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. |
| 主权项 |
1. A thermal recording material comprising:
a support and a coloring layer containing a colorless or pale colored dye precursor and a developer provided thereon, wherein the developer contains 2,4′-dihydroxydiphenylsulfone and 4,4′-dihydroxydiphenylsulfone, and a weight ratio of the 2,4′-dihydroxydiphenylsulfone and the 4,4′-dihydroxydiphenylsulfone is within a range of exceeding 50/50 and 95/5 or less, wherein the 2,4′-dihydroxydiphenylsulfone and the 4,4′-dihydroxydiphenylsulfone comprises 2,4′-dihydroxydiphenylsulfone and 4,4′-dihydroxydiphenylsulfone obtained by sequentially undergoing:
a separating step of obtaining a second mixture where a weight ratio of 2,4′-dichlorodiphenylsulfone is heightened from a first mixture containing the 2,4′-dichlorodiphenylsulfone and 4,4′-dichlorodiphenylsulfone,a reaction step of reacting the second mixture to obtain a third mixture containing the 2,4′-dihydroxydiphenylsulfone and the 4,4′-dihydroxydiphenylsulfone, anda post-treatment step of decolorizing and purifying the third mixture. |
