Abstract: The invention provides a heat-sensitive recording medium comprising (a) a support and (b) a heat-sensitive recording layer formed on the support and comprising a colorless or pale-colored basic dye and a color developing material capable of causing color development upon contact with the dye by heating, which medium is characterized in that the heat-sensitive recording layer contains at least one phosphate compound selected from the group consisting of 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate of the general formula (1) shown below and alkali metal, ammonium and polyvalent metal salts thereof: ##STR1## wherein R represents a tert-butyl group.

Abstract: The present invention provides a heat sensitive recording material having a recoridng layer formed on a substrate and containing a colorless or light-colored basic dye and a color developer, the heat sensitive recording material being characterized in that the color developer includes a zinc salt of terephthalaldehydic acid or a composite zinc salt of terephthalaldehydic acid and other aromatic carboxylic acid.

Abstract: In a multi-color heat sensitive recording material comprising a substrate and two or more heat sensitive color-forming layers thereon capable of forming different colors from each other, at least one of the heat sensitive color-forming layers containing a leuco dye and an acidic substance, the recording material characterized in that at least one piperidine derivative represented by the formula [I] ##STR1## wherein R.sub.1 is C.sub.1.about.30 aliphatic group residue which may have C.sub.2.about.20 alkoxycarbonyl group, or C.sub.1.about.30 aliphatic group residue which has ether linkage and oxycarbonyl group; R.sub.2, R.sub.3, R.sub.4, R.sub.5 and X are each methyl group or hydrogen atom; and l is an integer of 1 to 6, is incorporated at the position where a decolorizing function can be effected against the color-forming system comprising a leuco dye and an acidic substance.

Abstract: Disclosed is a two-color heat-sensitive recording material which comprises a base sheet and a recording layer of single-layer or multi-layer structure formed on the base sheet, the recording layer comrising:(a) a diazonium salt,(b) a basic leuco dye,(c) a 2-hydroxy-3-naphthoic acid derivative which acts as a coupler compound for causing the diazonium salt to develop color when heated and which also acts as a color developing material for causing the basic leuco dye to develop color when heated, and(d) a basic substance, wherein the diazonium salt and the basic leuco dye each form a color upon application of heat, thereby giving the first image of a mixed color, and, then, after irradiation of an active ray to decompose the diazonium salt, the basic leuco dye alone forms its own color upon application of heat, thereby giving the second image whose color is different from the mixed color of the first image.

Abstract: In a heat-sensitive recording material which comprises a substrate and a heat-sensitive recording layer thereon containing a diazonium salt and coupler compound, the heat-sensitive recording material characterized in that the coupler compound comprises at least one compound represented by the formula [I] below ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are each hydrogen atom, halogen atom, alkyl or alkoxyl; R.sub.9 is hydrogen atom or alkyl; X and Y are each hydrogen atom, --OR.sub.10 or --N(R.sub.11)(R.sub.12), R.sub.10, R.sub.11 and R.sub.12 being each hydrogen atom, alkyl, alicyclic group, aryl or aralkyl, these R.sub.10, R.sub.11 and R.sub.12 may have a substituent selected from among halogen atom, alkyl and alkoxy, R.sub.11 and R.sub.12 may link together to form a heteroring, or, one or both of R.sub.11 and R.sub.12 may form a heteroring together with an adjacent benzene ring; n is 0 or 1.

Abstract: A heat-sensitive recording material comprising a substrate and a heat-sensitive recording layer thereon, the heat-sensitive recording layer containing a diazonium salt, coupler compound, heat-fusible basic compound and at least one of the compounds represented by the formula [I] below ##STR1## wherein X is --O-- or --CONH--, R.sub.1 and R.sub.2 are each hydrogen, halogen, alkyl having 1 to 8 carbon atoms, cycloalkyl, aryl, aralkyl or alkoxyl and n is an integer of 1 to 10.

Abstract: This invention provides a heat-sensitive recording material comprising a substrate and a heat-sensitive recording layer which is formed over the substrate and which contains a diazonium salt, a coupler and at least one of specific heat-fusible basic amidine and diamidine compounds in which the nitrogen atom(s) of ##STR1## moiety(moieties) has(have) a substituent and the nitrogen atom(s) or ##STR2## moiety(moieties) has(have) at least one substituent, the substituent being independently selected from the group consisting of phenyl, naphthyl, phenyl-C.sub.1 -C.sub.4 alkyl and naphthyl-C.sub.1 -C.sub.4 alkyl, each optionally substituted with C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, phenyloxy, nitro or halogen, and in which amidine compounds are other than formamidines. The heat-sensitive recording material is especially excellent in storage stability.

Abstract: This invention provides a multicolor record material comprising a plurality of color forming systems each containing a color forming material and a color developing material and adapted to produce different colors individually, the multicolor record material being characterized in that each of the systems contains a substance which absorbs an infrared beam of specified wavelength for causing the system to produce its color but which substantially does not absorb an infrared beam of different wavelength for causing another system to produce the color thereof.

Abstract: A heat-sensitive record material for use with an infrared laser containing(a) a color forming material,(b) a color developing material, and(c) a light absorbing material selected from the group consisting of (1) natural or synthetic silicate compounds, and (2) baked products obtained by baking a zinc compound and a clay mineral at a temperature of at least 500.degree. C.

Abstract: A color developer is obtained by the process which comprises heating a mixture of at least one aromatic carboxylic acid, at least one water-insoluble organic polymer and at least one oxide or carbonate of polyvalent metal to melt at least one of aromatic carboxylic acid and said polymer to form a homogeneous mass. The color developer may be pulverized to form finely divided particles.