Abstract: A heat-sensitive recording material comprises a support, a heat-sensitive recording layer including a leuco dye and a developer, and a protective layer comprising a pigment and a binder. The heat-sensitive recording layer is located between the support and the protective layer. The pigment in the protective layer comprises secondary particles with an average particle diameter of about 30 to 900 nm formed preferably by aggregation of amorphous silica primary particles with a particle diameter of about 3 to 70 nm. The secondary particles are present in a proportion of about 5 to 35 mass % relative to total solids of the protective layer. The colloidal silica is present in a proportion of about 1 to 25 mass % relative to total solids of the protective layer.

Abstract: A heat-sensitive recording material comprises a support, a heat-sensitive recording layer including a leuco dye and a developer, and a protective layer comprising a pigment and a binder. The heat-sensitive recording layer is located between the support and the protective layer. The pigment in the protective layer comprises secondary particles with an average particle diameter of about 30 to 900 nm formed preferably by aggregation of amorphous silica primary particles with a particle diameter of about 3 to 70 nm. The secondary particles are present in a proportion of about 5 to 35 mass % relative to total solids of the protective layer. The colloidal silica is present in a proportion of about 1 to 25 mass % relative to total solids of the protective layer.

Abstract: Disclosed is a heat-sensitive recording material comprising a support and a heat-sensitive recording layer formed on the support and containing a leuco dye, a developer and a binder, wherein the heat-sensitive recording material uses as the developer at least two hydroxy-diphenylsulfone compounds such as 4-hydroxy-4?-isopropoxy-diphenylsulfone, 2,4?-dihydroxy-diphenylsulfone and the like, and uses as the leuco dye a black-color-forming leuco dye such as 3-di(n-butyl)amino-6-methyl-7-anilinofluoran or the like and 0.5 to 3.5 wt. %, relative to the black-color-forming leuco dye, of a red-color-forming leuco dye such as 3-diethylamino-7-chlorofluoran or the like.

Abstract: Disclosed is a heat-sensitive recording material comprising a support and a heat-sensitive recording layer formed on the support and containing a leuco dye, a developer and a binder, wherein the heat-sensitive recording material uses as the developer at least two hydroxy-diphenylsulfone compounds such as 4-hydroxy-4′-isopropoxy-diphenylsulfone, 2,4′-dihydroxy-diphenylsulfone and the like, and uses as the leuco dye a black-color-forming leuco dye such as 3-di(n-butyl)amino-6-methyl-7-anilinofluoran or the like and 0.5 to 3.5 wt. %, relative to the black-color-forming leuco dye, of a red-color-forming leuco dye such as 3-diethylamino-7-chlorofluoran or the like.