A description is given of a heat-sensitive recording material, comprising phenol-free organic color developers, more particularly comprising a color developer mixture comprising phenol-free organic color developers, of a heat-sensitive recording layer and also of a coating composition for producing it, of the use of the heat-sensitive recording material, of the use of an organic color developer of a formula I for improving the resistance of the printed image of a heat-sensitive recording material, and of a method for producing heat-sensitive recording material.

A heat-sensitive recording material including at least an undercoat layer and a heat-sensitive recording layer in this order on a support, the undercoat layer containing hollow particles and a binder, the heat-sensitive recording layer containing a leuco dye and a developer, the heat-sensitive recording material containing a compound represented by the following formula (1) as a first developer of the heat-sensitive recording layer:

##STR00001##

Disclosed is a heat-sensitive recording material comprising an undercoat layer and a heat-sensitive recording layer in this order on a support, the undercoat layer containing hollow particles, a binder, and an inorganic pigment I, the heat-sensitive recording layer containing a leuco dye, a developer, and an inorganic pigment II, and the heat-sensitive recording layer containing an N,N-diarylurea-based compound represented by the following formula (1): ##STR00001## wherein R.sub.2s may be the same or different, and each represents C.sub.1-12 alkyl, C.sub.7-12 aralkyl, or C.sub.6-12 aryl, and the aralkyl and the aryl may be each substituted with C.sub.1-12 alkyl, C.sub.1-12 alkoxy, C.sub.6-12 aryl, or halogen; A.sub.1s may be the same or different, and each represents hydrogen or C.sub.1-4 alkyl, as the developer, and a pigment with an oil absorption of 130 ml/100 g or less as the inorganic pigment II.

Non-phenolic direct thermal recording media have a thermally responsive layer containing a leuco dye and a plurality of diarylurea acidic developers selected to improve the quality and readability of the image produced in such media, particularly after being contacted with oils such as vegetable oil. The diarylurea developers preferably include, or consist essentially of, or consist of, N,N-diphenylurea (DPU) and a derivative of DPU. An exemplary combination is DPU together with a developer known commercially as TGMD.

Provided is a thermosensitive recording medium including a support and a thermosensitive recording layer disposed on or above the support. The thermosensitive recording layer include a compound represented by General Formula (1) and a styrene-acryl resin, where, in General Formula (1), R.sub.2 is a C1-12 straight-chain, branched-chain, or alicyclic alkyl group, C7-12 aralkyl group that is substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group or a halogen atom, or a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, where two or more R.sub.2 may be identical to or different from each other; and A.sub.1 is a hydrogen atom or a C1-4 alkyl group, where two or more A.sub.1, may be identical to or different from each other. ##STR00001##