Ricoh Company, Ltd.

Yasutomo Mori

Mitsuru Naruse

Mitsunobu Morita

Takeshi Kajikawa

Shuji Miyamoto

Kunihiko Hada

Kunio Hayakawa

Yoshikazu Kaneko

Norio Kurisu

Motoi Orihara

Keishi Taniguchi

Hiromi Furuya

Motoo Tasaka

Tomohisa Kakuda

Toshinobu Iwata

Kanjirou Kawasaki

Takeshi Yuyama

Hiroaki Inoue

Mikio Goto

Yuuichi Kawaguchi

Shuuji Miyamoto

There is provided a leuco dye dispersion liquid for a thermosensitive recording material wherein the leuco dye is being dispersed with an anionic surfactant and an nonionic surfactant, while average particle diameter of the leuco dye ranges from 0.10 &#x3bc;m to 0.30 &#x3bc;m and content of particles less than or equal to 0.07 &#x3bc;m in diameter of the dye is not greater than 1.0%. The leuco dye dispersion liquid shows no fogging, and can cause a high optical density of image on thermosensitive member with excellent brightness in background area, and a high durability for storage at elevated temperature.

Dye dispersion liquid and thermosensitive recording material using the same

A thermosensitive recording material having a support, a thermosensitive recording layer containing a leuco dye and a color developer, and an intermediate layer interposed therebetween. The intermediate layer contains hollow particles having a hollowness of 60 to 98%, a maximum particle diameter (D100) of 5.0 to 10.0 &mgr;m and a ratio D100/D50 of the maximum particle diameter (D100) to the median volume equivalent particle diameter (D50) in the range of 1.5 to 3.0. The hollow particles may be composed of a crosslinked polymer of a chlorine-free vinyl monomer.

Thermosensitive recording material

A thermosensitive recording material including a substrate, a thermosensitive coloring layer which is formed overlying the substrate and which induces color formation upon application of heat, and a protective layer which is formed overlying the thermosensitive coloring layer and which includes a resin, wherein the protective layer is formed by coating with a liquid including a core-shell type emulsion of the resin, and wherein the core-shell type emulsion of the resin is prepared by polymerizing monomers including (d) acrylamide and/or methacrylamide and (e) a vinyl monomer having a hydroxy group in the presence of a seed emulsion which is prepared by polymerizing monomers including (a) acrylamide and/or methacrylamide, (b) acrylonitrile and (c) a vinyl monomer having a hydroxy group.

A thermosensitive recording medium having a support, a thermosensitive layer provided on the support, and a protecting layer provided on the thermosensitive layer and containing montan wax particles having an average particle diameter AD of not greater than 1.5 .mu.m and such a particle size distribution that at least 99% of the montan wax particles have a particle diameter of not greater than (AD+0.5 .mu.m). The protecting layer is obtained by drying a layer of an aqueous dispersion containing an aqueous emulsion of the montan wax particles.

Thermosensitive recording medium

A thermosensitive recording medium having a support, a thermosensitive layer provided on the support and capable of forming a color image when heated imagewise, and a protecting layer provided on the thermosensitive layer and containing a pigment and a core-shell resin obtained by polymerizing a vinyl monomer in an emulsion containing acrylonitrile-containing polymer seeds such that a polymer of the vinyl monomer is copolymerized on each of the seeds to form a shell surrounding a core of the seed, wherein the core-shell resin meets with at least one of the following criteria (a) and (b):

A thermosensitive recording medium including a support, and at least one layer provided on the support, wherein one of the at least one layer is a thermosensitive layer capable of forming a color image when heated imagewise, and one of the at least one layer contains a zinc dithiocarbamate of the formula: ##STR1## wherein R.sup.1 and R.sup.2 stand independently from each other for an alkyl group having 1-4 carbon atoms or a phenyl group. The zinc dithiocarbamate is contained in the thermosensitive layer or an intermediate layer interposed between the thermosensitive layer and the support.

A thermosensitive recording medium is disclosed which includes a support, and a thermosensitive color-developing layer formed on the support and containing a leuco dye having a melting point of at least 200.degree. C. and a color developer having a melting point of at least 180.degree..

A thermosensitive recording material having a high degree of background whiteness, superior light resistance without coloring of the background when exposed to the light, and a method of producing a stable coating liquid or forming a thermosensitive coloring layer and a protective layer are provided.

Thermosensitive recording material and production process thereof

A thermosensitive recording material of this invention has a support, on which a thermosensitive color developing layer mainly composed of a leuco dye and a color developer which is contacted with the leuco dye while heating to develop a color and a protective layer mainly composed of polyvinyl alcohol together with either aziridine compound or dimethylolurea are successively provided, the color developer being at least one of phthalic acid derivatives represented by the following general formula (I): ##STR1## wherein R.sub.1, X, Y and 1 are as defined in above. The thermosensitive recording material of this invention is excellent in sensitivity and density of the color development and has the high storage stability of the recorded images. Accordingly, the thermosensitive recording material of this invention is very useful. The selected inorganic filler may be incorporated in the thermosensitive color developing layer and/or the protective layer.

Thermosensitive recording materials

A thermosensitive recording material composed of a support, a thermosensitive recording layer formed on the support, capable of producing colored images by heating, and a protective layer formed on the thermosensitive recording layer, which contains as a resin component a copolymer resin obtained by copolymerization of arylamide or methacrylamide, acrylonitrile, and a vinyl monomer having a carboxyl group, or a copolymer resin of a core-shell emulsion type obtained by copolymerization of acrylamide and/or methacrylamide in the presence of a seed emulsion of an acryl-based copolymer or methacryl-based copolymer, and as a crosslinking agent a compound having two or more alkyleneimino groups, a carbodiimide compound, a methyl ethyl ketoxime compound, or bis(.beta.-hydroxyethyl)sulfone.

A thermosensitive recording material comprising (a) a support, and (b) a thermosensitive recording layer formed on the support, comprising a leuco dye and a color developing agent comprising a metal salt or metal complex of a compound having formula (I), which is capable of inducing color formation in the leuco dye upon application of heat thereto: ##STR1## wherein X represents a halogen, an alkyl group having 1 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms; R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 independently represent hydrogen, a halogen, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, an aralkyloxyl group having 7 to 20 carbon atoms, an aryloxyl group having 6 to 20 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aralkylthio group having 6 to 20 carbon atoms or an arylthio group having 6 to 20 carbon atoms, R.sup.1 and R.sup.2, or R.sup.2 and R.sup.3 may form together with an adjacent benzene ring a naphthalene ring, a tetrahydronaphthalene ring or an indan ring; and m is an integer of 1 to 4.

A thermosensitive recording material is disclosed, which comprises a substrate, a thermosensitive coloring layer comprising a leuco dye and a color developer capable of inducing color formation in the leuco dye, formed on the substrate, and a protective layer comprising at least one inorganic pigment selected from the group consisting of silica and calcium carbonate, each having an average particle diameter of 0.1 .mu.m or less, and a water-soluble binder, formed on the thermosensitive coloring layer.

A thermosensitive recording material is disclosed, which comprises a support, an intermediate layer having a voidage ranging from 50% to 95% and a thickness of 3 .mu.m to 100 .mu.m, and a thermosensitive coloring layer, which layers are successively formed on the intermediate layer.

Growing community of inventors

Numazu, Japan

Yasutomo Mori