Kanzaki Paper Manufacturing Co., Ltd.

Kanzaki Paper Mfg. Co., Ltd.

Sanko Kaihatsu Kagaku Kenkyusho

Shuki Okauchi

Toshitake Suzuki

Toranosuke Saito

Hironari Fujioka

Takashi Ishibashi

Tsunefumi Yamori

Masakatu Kitani

Fumio Seyama

Kazuo Kojima

Masato Kawamura

Takuji Tuji

Yoshiyuki Nukushina

A heat-sensitive recording material is obtained by coating an aqueous dispersion which is prepared by mixing an aqueous dispersion of an electron donating colorless dye with an aqueous dispersion of an electron accepting compound on a base sheet. The aqueous dispersion of an electron donating dye is prepared by a method which comprises the steps of uniformly dispersing at least one electron donating colorless dye and at least one heat-fusible substance selected from the group consisting of 2-benzyloxynaphthalene, parabenzyl biphenyl, 1,4-bis(2-vinyloxyethoxy)benzene, bis [2-(4-methoxyphenoxy)ethyl] ether, 1,2-bis (3-methylphenoxy)ethane, 1,2-diphenoxyethane, benzyl 4-methylthiophenyl ether, 1-(2-methylphenoxy)-2-(4-methoxyphenoxy)ethane and oxalic acid dibenzyl ester with a dispersing binder and/or a surface active agent in water; and pulverizing thus obtained dispersion with use of a horizontal sand mill.

Method for producing a heat-sensitive recording material

A heat sensitive recording material comprising a substrate and a recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor reactive with the dye to form a color when contacted therewith, the recording material being characterized in that, as the color acceptor is used at least one compound selected from the group consisting of 4-hydroxy-4'-isopropyloxydiphenylsulfone, 4,4'-(1,3-dimethylbutylidene) bisphenol, 4,4'-(1-phenylethylidene)bisphenol, 4,4'-(p-phenylenediisopropylidene)bisphenol and 4,4'-(m-phenylenediisopropylidene) bisphenol, and to the recording layer is added at least one of a heat-fusible substance represented by the formula [I] ##STR1## wherein X is hydrogen atom, halogen atom, C.sub.1.about.4 alkyl or C.sub.1.about.4 alkoxy.

Heat sensitive recording material

In a heat sensitive recording material comprising a substrate and a heat sensitive recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor which is reactive with the dye to form a color when contacted therewith, the recording material characterized in that at least one of the compounds of the formula (I) is contained in the heat sensitive recording layer ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are same or different and are hydrogen atom, halogen atom, C.sub.1 .about.C.sub.5 alkyl or C.sub.1 .about.C.sub.5 alkoxyl.

In the method for the production of a dispersion of colorless chromogenic material useful for the production of a heat-sensitive record material, a colorless chromogenic material and a heat fusible material are admixed together and heated to form a co-melt, the co-melt is dispersed in hot water having a temperature higher than the solidifying point of the co-melt to form an emulsion without causing solidification of the co-melt, and then the emulsion thus obtained is further dispersed in a water having a temperature lower than the solidification point of the co-melt to form a dispersion in which solid particles of the co-melt are dispersed.

Method for the production of a dispersion of colorless chromogenic

A process for the production of heat-sensitive recording materials is described, comprising the steps of (1) applying to a support a coating composition comprising a color former, a color developer, and at least one of a water-soluble binder and a water-dispersible binder, to form a layer, and (2) irradiating the layer with electron beams. Images recorded on the heat-sensitive recording material exhibit superior stability. The color density of the recorded images remains stable even when the recording material is moistened with water or placed in a high humidity atmosphere. Further, even moistened recorded images do not disappear when rubbed with a finger.

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Osaka, Japan

Shuki Okauchi