Patent ID: 7071144

Claim:
A thermal recording material having a thermal recording layer comprising a generally colorless or light-colored electron-donating dye precursor and an electron-accepting developer that reacts under heat to cause said dye precursor to form a color, said thermal recording layer comprising: 4,4′-dihydroxydiphenylsulfone (1), an amide derivative of the general formula (2), wherein A is an alkyl group, an alkenyl group or an alkylamino group, each of R 3 and R 4 may be the same as, or different from, other and is a hydrogen atom, an alkyl group, an alkenyl group, an aralkyl group or an aryl group, and a fluorane derivative of the general formula (3), wherein each R 5 and R 6 may be the same as, or different from, other and is an alkyl group having 1 to 5 carbon atoms, a cyclohexyl group or an aryl group, R 7 is a hydrogen atom, methyl, trifluoromethyl or a halogen atom and R 8 is a hydrogen atom, methyl or a halogen atom, wherein the weight ratio of the 4,4′-dihydroxydiphenylsulfone (1) and the amide derivative of the general formula (2) (compound (1)/compound (2)) is 2/1 to 1/2, and wherein said thermal recording layer comprises at least one compound selected from the group consisting of a compound of the general formula (4), a compound of the general formula (5), and a compound of the general formula (7), wherein the compound of the general formula (4) is wherein each of R 9 , R 10 and R 11 may be the same as, or different from, each other and is a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkali metal, an alkaline earth metal, a transition metal or an amine, and any two substituents of R 9 , R 10 and R 11 may bond to each other and form a ring, wherein the compound of the general formula (5) is wherein R 12 is a group of the general formula (6), in which R 15 is cyclohexyl, phenyl or tert-butyl and R 16 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, cyclohexyl, phenyl or tert-butyl, R 13 is a covalent bond or an alkylene group having 1 to 3 carbon atoms and R 14 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or any group represented by R 12 , and wherein the compound of the general formula (7) is wherein R 17 is a covalent bond, an alkylene group having 1 to 8 carbon atoms or a group of the general formula (8). in which R 20 is 2,2,6,6-tetramethyl-4-piperidyl or 1,2,2,6,6-pentamethyl-4-piperidyl, and each of R 18 and R 19 may be the same as, or different from, each other and is 2,2,6,6-tetramethyl-4-piperidyl or 1,2,2,6,6-pentamethyl-4-piperidyl.