Thermosensitive recording material

A thermosensitive recording material comprising:

• a sheet substrate and
• a thermosensitive colored image-forming layer formed on a surface of the sheet substrate and comprising a substantially colorless dye precursor, a color developing agent reactive with the dye precursor upon heating to thereby develop a color, and a binder,
• said color developing agent comprising at least one compound of the formula (I):
• ##STR29## wherein X represents a member selected from the group consisting of oxygen and sulfur atoms, R represents a member selected from the group consisting of unsubstituted aromatic hydrocarbon groups and substituted aromatic hydrocarbon groups having at least one susbstituent selected from the group consisting of lower alkyl groups and halogen atoms;
• A represents a multivalent group, and n represents an integer of 2 or more, and
• said thermosensitive colored image-forming layer further comprising an additive comprising at least one member selected from the group consisting of:
• (1) aromatic epoxy compounds having at least one epoxy group per molecule thereof,
• (2) aromatic aziridine compounds having at least one aziridinyl group per molecule thereof,
• (3) aromatic compounds of the formulae (II), (III) and (IV):
• ##STR30## wherein Y represents a member selected from the group consisting of oxygen and sulfur atoms, R.sup.1 represents a member selected from the group consisting of unsubstituted aromatic ring groups, and substituted benzene ring groups having at least one substituent selected from the group consisting of lower alkyl groups and halogen atoms, and R.sup.2 represents a member selected from the group consisting of alkyl groups, aralkyl groups, unsubstituted aromatic ring groups, and substituted aromatic ring groups having at least one substituent selected from the groups consisting of alkyl;
• groups, aryl groups, aralkyl groups and halogen atoms, ##STR31## wherein Z and Q respectively and independently from each other represent a member selected from the group consisting of oxygen and sulfur atoms;
• R.sup.3 represents a member selected from the group consisting of unsubstituted benzene ring groups, unsubstituted aromatic ring groups and substituted benzene ring groups having at least one substituent selected from the group consisting of lower alkyl groups, aryl groups and halogen atoms, and R.sup.4 represents a member selected from the group consisting of (i) aralky groups, (ii) alkyl groups substituted with an aryloxy group, (iii) substituted benzene ring groups, (iv) substituted polynuclear aromatic ring groups, (v) unsubstituted benzene ring groups and (vi) unsubstituted polynuclear aromatic ring groups, wherein each of the substituted benzene ring groups (iii) and the substituted polynuclear aromatic ring groups (iv) has at least one substituent selected from the group consisting of alkyl, alkenyl, aryl, aralkyl, alkyloxy, aryloxy, aralkyloxy, alkylmercapto, arylmercapto, aralkylmercapto, alkyloxycarbonyl, aryloxycarbonyl, aralkyloxycarbonyl groups and halogen atoms, and ##STR32## wherein E represents a member selected from the group consisting of oxygen and sulfur atoms;
• R.sup.5 represents a member selected from the group consisting of unsubstituted aromatic ring groups, and substituted benzene ring groups having at least one substituent selected from the group consisting of lower alkyl groups and halogen atoms, and R.sup.6 and R.sup.7 respectively and independently from each other represents a member selected from the group consisting of a hydrogen atom, unsubstituted alkyl groups, aralkyl groups, alkyl groups substituted with an aryloxy group, unsubstituted aromatic ring groups, and substituted aromatic ring groups having at least one substituent selected from the group consisting of alkyl, aryl, aralkyl, alkyloxy, alkyloxycarbonyl, aryloxycarbonyl, aralkyloxycarbonyl, arylsulfonyl and halogen,
• (4) aromatic sulfonyl compounds different from the compounds of the formulae (I), (II), (III) and (IV), provided with at least one sulfonyl group per molecule thereof and having a melting point of from 60.degree. C. to 160.degree. C., and
• (5) basic white pigments.