EP1504920B1 - Thermal recording material - Google Patents

Thermal recording material Download PDF

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Publication number
EP1504920B1
EP1504920B1 EP02753221A EP02753221A EP1504920B1 EP 1504920 B1 EP1504920 B1 EP 1504920B1 EP 02753221 A EP02753221 A EP 02753221A EP 02753221 A EP02753221 A EP 02753221A EP 1504920 B1 EP1504920 B1 EP 1504920B1
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EP
European Patent Office
Prior art keywords
heat
dispersion
sensitive recording
color
parts
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EP02753221A
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German (de)
English (en)
French (fr)
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EP1504920A4 (en
EP1504920A1 (en
Inventor
Shigetoshi Seki
Toshiro Hata
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New Oji Paper Co Ltd
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Oji Paper Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/333—Colour developing components therefor, e.g. acidic compounds
    • B41M5/3333—Non-macromolecular compounds
    • B41M5/3335—Compounds containing phenolic or carboxylic acid groups or metal salts thereof
    • B41M5/3336—Sulfur compounds, e.g. sulfones, sulfides, sulfonamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/323—Organic colour formers, e.g. leuco dyes
    • B41M5/327—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring
    • B41M5/3275—Fluoran compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/42—Intermediate, backcoat, or covering layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/42—Intermediate, backcoat, or covering layers
    • B41M5/44—Intermediate, backcoat, or covering layers characterised by the macromolecular compounds

Definitions

  • the present invention relates to a heat-sensitive recording material employing a color forming, reaction between a leuco dye and a developer.
  • Recording devices in which a heat-sensitive recording material haying a heat-sensitive recording layer containing a leuco dye, a developer and a binder and formed on one side of a support composed of paper, synthetic paper, plastic film or the like is used as a recording media, are compact and inexpensive and are also easy to maintain. Therefore, in addition to being used as recording media in facsimile systems, automatic ticket vending-machines, scientific measuring instruments and so on, they are also extensively used as output media in printers or plotters for POS labels, CAD, CRT medical images and the like.
  • heat-sensitive recording materials employing synthetic papers having multi-layer structures and heat-sensitive recording material employing a biaxially oriented thermoplastic resin film optionally containing inorganic pigments are used.
  • Heat-sensitive recording materials in which at least two kinds of hydroxy-diphenylsulfone compounds such as 4-hydroxy-4'-isopropoxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone and the like are used as a developer to increase the stability of a recorded portion, are disclosed in Japanese Unexamined Patent Publications Nos. 1990-020385, 1990-249690, 1993-286255, 1995-172068, 2000-263944 and 2001-001647. However, there are further demands for less change in the density of a recorded portion over time caused by humidity and temperature, and for improved gradation of the recorded portion.
  • heat-sensitive recording materials are required to give a recorded portion with an achromatic black color (or pale charcoal color, gray).
  • Japanese Unexamined Patent Publications Nos. 1993-254254 and 1996-324130 disclose heat-sensitive recording materials in which a combination of a black-color-forming leuco dye and a red-color-forming leuco dye is used to give such an achromatic black color to a recorded portion thereof.
  • JP-A-2001-088450 describes a heat-sensitive recording material containing at least a black coloring leuco dye and a red coloring leuco dye, wherein at least a 3-N-methyl-N-cyclohexylamino-6-methyl-7anilinofluoran is contained therein as the black coloring leuco dye.
  • JP-A-05-278328 describes a heat-sensitive recording material comprising a support and a heat-sensitive coloring layer formed on at least one surface of the support.
  • a heat-sensitive recording material comprising a support and a heat-sensitive coloring layer formed on at least one surface of the support.
  • further improvements are demanded in the recording sensitivity and the hue or gradation of a recorded portion thereof.
  • grade employed herein means that the recording energy applied and the density (optical density) of the recorded portion (recorded image) are substantially directly proportional (linearly proportional). More specifically, a recorded image is formed with a density proportional to the intensity of recording energy applied; and the density of the recorded portion (recorded image) and the recording energy applied are in a nearly linear relationship. As a result, when multiple recorded portions (recorded images) are formed by changing (increasing or decreasing) the intensity of the recording energy applied in a stepwise manner, the resulting recorded portions (recorded images) exhibit clear gradation throughout their density range (from the lowest density to the highest density). Excellent gradation leads to excellent image quality.
  • An object of the invention is to provide a heat-sensitive recording material in which the hue of the recorded portion (recorded image) is a nearly achromatic black color, the recorded portion (recorded image) is excellent in gradation, and the density of the recorded portion exhibits substantially no change over time under the influence of humidity or temperature.
  • the present invention uses at least two kinds of hydroxy-diphenylsulfone compounds as the developer and also uses as the leuco dye a black-color-forming leuco dye and 0.5 to 3.5 wt.%, relative to the black-color-forming leuco dye, of a red-color-forming leuco dye.
  • the present invention provides the following heat-sensitive recording materials.
  • a heat-sensitive recording material comprising (a) a support and (b) a heat-sensitive recording layer formed on the support and containing a leuco dye, a developer and a binder, the heat-sensitive recording layer containing at least two hydroxy-diphenylsulfone compounds as the developer and a black-color-forming leuco dye and a red-color-forming leuco dye as the leuco dye, the red-color-forming leuco dye being present in an amount of 0.5 to 3.5 wt.% relative to the black-color-forming leuco dye wherein the hydroxy-diphenylsulfone compounds are a mixture of 4-hydroxy-4'-isopropoxydiphenylsulfone and at least one member selected from the group consisting of 2,4'-dihydroxy-diphenylsulfone and 4,4'-dihydroxy-diphenylsulfone, wherein the black-color-forming leuco dye is at least one member selected from the group consisting of 3-d
  • Item 2 The heat-sensitive recording material according to Item 1 wherein said at least one member selected from the group consisting of 2,4'-dihydroxy-diphenylsulfone and 4,4'-dihydroxy-diphenylsulfone is used in an amount of about 0.5 to about 2.0 parts by weight per part by weight of 4-hydroxy-4'-isopropoxy-diphenylsulfone.
  • Item 3 The heat-sensitive recording material according to Item 1, wherein the black-color-forming leuco dye is a mixture of 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran and at least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran and 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran.
  • the black-color-forming leuco dye is a mixture of 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran and at least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran and 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran.
  • Item 4 The heat-sensitive recording material according to Item 3 wherein 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran is used in an amount of 30 to 300 wt.% relative to said at least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran and 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran.
  • Item 5 The heat-sensitive recording material according to Item 1 which contains the red-color-forming leuco dye in an amount of about 0.8 to about 3.0 wt.% relative to the black-color-forming leuco dye.
  • Item 6 The heat-sensitive recording material according to Item 1 wherein the heat-sensitive recording layer further comprises a blue-color-forming leuco dye in an amount of about 0.5 to 5 wt.% relative to the black-color-forming leuco dye.
  • Item 7 The heat-sensitive recording material according to Item 1 wherein a water dispersible resin is contained as the binder in the heat-sensitive recording layer.
  • Item 8 The heat-sensitive recording material according to Item 1 wherein the heat-sensitive recording layer further comprises a sensitizer, a print stability-improving agent or a mixture thereof.
  • Item 9 The heat-sensitive recording material according to Item 1 which further comprises a protective layer formed on the heat-sensitive recording layer.
  • Item 10 The heat-sensitive recording material according to Item 1 which contains the red-color-forming leuco dye in an amount of 0.5 to 3.0 wt.% relative to the black-color-forming leuco dye.
  • Figure 1 is a graph illustrating the relationship between the intensity of the recording energy applied and the density of the recorded portion with respect to the heat-sensitive recording materials of Example 1 and Comparative Example 3.
  • the present invention is characterized in that the heat-sensitive recording layer contains at least two hydroxy-diphenylsulfone compounds as a developer, and contains at least a black-color-forming leuco dye and 0.5 to 3.5 wt.%, based on the black-color-forming leuco dye, of a red-color-forming leuco dye.
  • hydroxy-diphenylsulfone compounds include 4-hydroxy-4'-methoxy-diphenylsulfone, 4-hydroxy-4'-isopropoxy-diphenylsulfone, 4-hydroxy-4'-n-propoxy-diphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 2,4'-dihydroxy-diphenylsulfone, 4,4'-dihydroxy-diphenylsulfone, 3,3'-diallyl-4,4'-dihydroxy-diphenylsulfone, 3,4-dihydroxy-4'-methyl-diphenylsulfone, 2,2'-[4-(4-hydroxyphenylsulfonyl)phenoxy]diethylether and the like.
  • a mixture of 4-hydroxy-4'-isopropoxy-diphenylsulfone and at least one member selected from the group consisting of 2,4'-dihydroxy-diphenylsulfone and 4,4'-dihydroxy-diphenylsulfone is used.
  • the use of about 0.2 to about 5.0 parts by weight, especially about 0.5 to about 2.0 parts by weight, of at least one member selected from the group consisting of 2,4'-dihydroxy-diphenylsulfone and 4,4'-dihydroxy-diphenylsulfone per part by weight of 4-hydroxy-4'-isopropoxy-diphenylsulfone gives a nearly achromatic black color even in low density recorded portions having an optical density of 0.4 to 0.8.
  • 2,4'-dihydroxy-diphenylsulfone and 4,4'-dihydroxy-diphenylsulfone 2,4'-dihydroxy-diphenylsulfone is preferred because it imparts better resistance to background fogging.
  • the total amount of the hydroxy-diphenylsulfone compounds used is about 15 to about 60 wt.%, preferably about 20 to about 50 wt.%, relative to the total solids of the heat-sensitive recording layer.
  • the heat-sensitive recording layer contains the above-mentioned hydroxy-diphenylsulfone compounds as a developer, and if necessary, various other known developers can additionally be used insofar as the desired effects of the invention are not impaired.
  • Examples of other developers include phenolic compounds such as 1,3,3-trimethyl-1-(p-hydroxyphenyl)-6-hydroxyindan, 4,4'-isopropylidenediphenol, 4,4'-cyclohexylidenediphenol, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, benzyl 4-hydroxybenzoate, 1,1-bis(4-hydroxyphenyl)-1-phenylethane and the like; those having one or more -SO 2 NH- bonds within the molecule, such as p-cumylphenyl N-(p-tolylsulfonyl)carbamate, N-(o-tolyl)-p-tolylsulfoamide, 4,4'-bis(N-p-tolylsulfonylaminocarbonylamino)diphenylmethane and the like; zinc salts of aromatic carboxylic acids such as zinc 4-[2-(p-methoxyphenoxy)ethyloxy]salicylate,
  • the amount of said other developers is suitably selected, but usually ranges from about 3 to about 15 wt.%, particularly from about 5 to about 10 wt.%, relative to the total amount of the above hydroxy-diphenylsulfone compounds used.
  • the heat-sensitive recording layer of the heat-sensitive recording material of the invention contains at least a black-color-forming leuco dye and a specified amount of a red-color-forming leuco dye.
  • recorded portions excellent in hue, gradation and background-fogging resistance, and also excellent in heat resistance and moisture resistance are obtained by the combined use of a black-color-forming leuco dye and a specified amount of a red-color-forming leuco dye, in addition to the use of at least two hydroxy-diphenylsulfone compounds described above.
  • black-color-forming leuco dyes include a wide variety of known black-color-forming leuco dyes used in the art, such as 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluoran, 3-(N-methyl-N-cyclohexyl)amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di(n-butyl)amino-6-methyl-7-anilinofluoran, 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran, 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran, 3-di(n-butyl)amino-7-(o-fluoroanilino)fluoran, 3-(N-ethyl-p-toluidino)-6-methyl-7-methyl-7
  • At least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran, 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran and 3-di(n-butyl)arnino-7-(o-chloroanilino)fluoran is used for imparting excellent gradation of the recorded portions and excellent background-fogging resistance.
  • 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran in combination with at least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran and 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran.
  • 3-di (n-butyl)amino-7-(o-chloroanilino)fluoran in an amount of about 30 to about 300 wt.%, more preferably about 50 to about 150 wt.%, relative to at least one member selected from the group consisting of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran and 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran.
  • red-color-forming leuco dyes such as 3,3'-bis(p-dimethylaminophenyl)phthalide, 3-(N-ethyl-N-isoamyl)amino-7-phenoxyfluoran, 3-cyclohexylamino-6-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-7-chlorofluoran, rhodamine(o-chloroanilino)lactam, 3-diethylamino-6,8-dimethylfluoran, 3,3'-bis(1-n-butyl-2-methylindol-3-yl)phthalide and the like.
  • 3-diethylamino-7-chlorofluoran is used.
  • Leuco dyes are not limited to those specified above, and two or more black-color-forming leuco dyes and two or more red-color-forming leuco dyes may also be used in combination.
  • the red-color-forming leuco dye is employed in an amount of 0.5 to 3.5 wt.% relative to the black-color-forming leuco dye.
  • Low-density recorded portions having an optical density of 0.2 to 0.6 is likely to have a black color with a greenish hue when the red-color-forming leuco dye is used in an amount of less than 0.5 wt.%, and is likely to have a black color with a reddish hue when it is used in an amount of more than 3.5 wt.%. Therefore, the amount of the red-color-forming leuco dye is preferably about 0.8 to about 3.0 wt.%, more preferably about 1.0 to about 2.0 wt.%, relative to the black-color-forming leuco dye.
  • the heat-sensitive recording layer may contain other leuco dyes insofar as the desired effects of the invention are not impaired.
  • leuco dyes include blue-color-forming leuco dyes such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylamino-2-methylphenyl)-3-(4-dimethylaminophenyl)-6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo[a]fluoran and the like; green-color-forming leuco dyes such as 3-(N-ethyl-N-p-tolyl)amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran and the like; and leuco dyes having absorption wavelengths in the near inf
  • leuco dyes are preferably used in an amount of about 0.3 to about 15 wt.%, especially about 0.5 to about 10 wt.%, relative to the black-color-forming leuco dye.
  • the blue-color-forming leuco dye is preferably used in an amount of about 0.5 to about 5 wt.%, especially about 1.0 to about 3.0 wt.%, relative to the black-color-forming leuco dye.
  • the total amount of black-color-forming leuco dye and red-color-forming leuco dye used preferably is about 5 to about 35 wt.%, especially about 10 to about 25 wt.%, relative to the total solids content of the heat-sensitive recording layer.
  • the heat-sensitive recording layer is formed, for example, as follows.
  • a black-color-forming leuco dye, a red-color-forming leuco dye, a developer comprising at least two hydroxy-diphenylsulfone compounds, and if desired, a sensitizer, a print stability-improving agent and the like are pulverized usually in water serving as a dispersion medium, either jointly or separately, by means of a ball mill, an attritor, a sand mill or like mixing and pulverizing apparatus to an average particle diameter of about 2 ⁇ m or less.
  • a binder is added to the resulting dispersion, giving a heat-sensitive recording layer coating composition.
  • the coating composition is applied to a support, and the coating is dried.
  • binders examples include water-soluble resins such as graft copolymers of starch and polyvinyl acetate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, oxidized starch, casein, styrene-maleic anhydride copolymer, methylvinylether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer and the like; and water-dispersible resins such as styrene-butadiene-based latex, acrylic latex, urethane-based latex and the like. Among them, water-dispersible resins are preferred.
  • the amount of the binder to be employed is not particularly limited but is preferably about 5 to about 40 wt.%, especially about 20 to about 35 wt.%, relative to the heat-sensitive recording layer.
  • the heat-sensitive recording layer may contain a sensitizer to optimize the recording sensitivity and a print stability-improving agent to enhance the long-term stability of recorded portions.
  • sensitizers include stearic acid amide, methylenebisstearamide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, 2-naphthyl benzyl ether, m-terphenyl, p-benzylbiphenyl, p-tolyl biphenyl ether, di (4-methoxyphenoxyethyl)ether, 1,2-di(3-methylphenoxy)ethane, 1,2-di(4-methylphenoxy)ethane, 1,2-di(4-methoxyphenoxy)ethane, 1,2-di(4-chlorophenoxy)ethane, 1,2-diphenoxyethane, 1-(4-methoxyphenoxy)-2-(3-methylphenoxy)ethane, p-methylthiophenylbenzyl ether, di( ⁇ -biphenylethoxy)benzene, di(p-chlorobenzyl) oxalate,
  • print stability-improving agents include hindered phenol compounds such as 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-thiobis(2-methyl-6-tertbutylphenol), 4,4'-butylidenebis(6-tert-butyl-m-cresol), 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane and the like; and epoxy compounds such as 4,4'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4'-
  • the amounts of the sensitizer and the print stability-improving agent employed are not particularly limited; but each of the amounts thereof is usually about 0.1 to about 4 parts by weight, preferably about 0.5 to about 3 parts by weight, per part by weight of the total amount of the leuco dyes contained in the heat-sensitive recording layer.
  • the heat-sensitive recording layer coating composition may contain various auxiliaries if so desired.
  • auxiliaries include pigments such as kaolin, precipitated calcium carbonate, ground calcium carbonate, calcined kaolin, titanium oxide, magnesium carbonate, aluminium hydroxide, amorphous silica, urea-formalin resin filler and the like; surfactants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, fatty acid metal salts and the like; waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax and the like; insolubilizers such as glyoxal, urea formalin resin, polyamide epoxy resin, polyamideamine-epichlorohydrin resin, adipic dihydrazide, boric acid, borax, ammonium zirconium carbonate and the like; and ultraviolet
  • the heat-sensitive recording layer coating composition is applied in an amount of about 2 to about 12 g/m 2 , preferably about 3 to about 7 g/m 2 , on a dry weight basis.
  • the heat-sensitive recording layer coating composition is applied to a support according to a coating method conventionally used in the art such as air knife coating, pure blade coating, rod blade coating, bar coating, curtain coating, die coating, gravure coating or the like, and then the resulting coating layer is dried.
  • any known supports used in the art can be used. Especially, examples include deinked pulp-containing recycled paper, neutralized or acidic wood-free paper, coated paper, synthetic paper, transparent plastic film, colored transparent plastic film, white plastic film and the like.
  • the thickness of these supports is suitably selected from a wide range. Preferable thickness is generally about 40 to about 250 ⁇ m.
  • a protective layer may be provided on the heat-sensitive recording layer to enhance chemical resistance or water resistance of the recorded portion, or to improve runnability during recording.
  • a protective layer is formed, for example, by applying to the heat-sensitive recording layer a protective layer coating composition which contains a binder with film-forming ability, and drying the resulting layer.
  • binder which may be contained in the protective layer coating composition
  • those binders which can be incorporated in the above heat-sensitive recording layer coating composition may be used.
  • Such binder is preferably used in an amount of about 20 to about 100 wt.%, especially about 30 to about 95 wt.%, based on the total solids content of the protective layer.
  • the protective layer coating composition may contain, if necessary, the aforementioned various auxiliaries which may be incorporated into the heat-sensitive recording layer coating composition.
  • the protective layer coating composition is applied in an amount of about 0.5 to about 10 g/m 2 , preferably about 1 to about 5 g/m 2 , on a dry weight basis.
  • the protective layer coating composition can be applied to the heat-sensitive recording layer according to a coating method known in the art such as air knife coating, pure blade coating, rod blade coating, bar coating, curtain coating, die coating, gravure coating or the like, and then the resulting coating layer is dried.
  • an undercoat layer containing oil-absorbing pigments or hollow particles as main components may be provided between the support and the heat-sensitive recording layer; a glossy layer may be provided by applying to the protective layer a coating composition containing an electron beam- or UV-curable compound as a main component and curing the coating by an electron beam or a UV ray; or a smoothing treatment may be provided by a supercalender after the formation of each layer.
  • the heat-sensitive recording material of the present invention may be modified, if necessary, by utilizing a variety of other known techniques used in the production of heat-sensitive recording materials.
  • a composition composed of 10 parts of 4-hydroxy-4'-isopropoxy-diphenylsulfone, 4 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 8 parts of a 5% aqueous solution of hydroxypropyl methylcellulose was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.5 ⁇ m, giving Dispersion A.
  • a composition composed of 10 parts of 2,4'-dihydroxy-diphenylsulfone, 4 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 8 parts of a 5% aqueous solution of hydroxypropyl methylcellulose was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.5 ⁇ m, giving Dispersion B.
  • a composition composed of 10 parts of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran, 10 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 10 parts of water was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.0 ⁇ m, giving Dispersion C.
  • a composition composed of 10 parts of 3-di(n-butyl)amino-7-(o-chloroanilino)fluoran, 10 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 10 parts of water was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.0 ⁇ m, giving Dispersion D.
  • a composition composed of 10 parts of 3-diethylamino-7-chlorofluoran, 10 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 10 parts of water was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.0 ⁇ m, giving Dispersion E.
  • a composition composed of 10 parts of 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 10 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 10 parts of water was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.0 ⁇ m, giving Dispersion F.
  • a composition composed of 10 parts of 1,2-di(3-methylphenoxy)ethane, 10 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 10 parts of water was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.5 ⁇ m, giving Dispersion G.
  • a heat-sensitive recording layer coating composition was prepared by stirring a composition composed of 30 parts of Dispersion A, 30 parts of Dispersion B, 30 parts of Dispersion C, 30 parts of Dispersion D, 0.6 part of Dispersion E, 1.0 part of Dispersion F, 18 parts of Dispersion G, 45 parts of styrene-butadiene latex (glass transition temperature: -5°C, solids content: 48 %), 95 parts of a 13 % aqueous solution of polyvinyl alcohol (trade name: PVA105® , manufactured by Kuraray Co., Ltd.), 12 parts of amorphous silica (trade name: Mizukasil® P-527, manufactured by Mizusawa Industrial Chemicals,Ltd.) and 60 parts of water.
  • PVA105® polyvinyl alcohol
  • amorphous silica trade name: Mizukasil® P-527, manufactured by Mizusawa Industrial Chemicals,Ltd.
  • a protective layer coating composition was prepared by stirring a composition composed of 70 parts of a 60 % aqueous slurry of kaolin (average particle diameter: 0.8 ⁇ m), 15 parts of an aqueous dispersion of zinc stearate. (trade name: Hidorin® Z-7-30, solids content: 31.5 %), 2.00 parts of a 10.% aqueous solution of acetoacetyl-modified polyvinyl alcohol (trade name: Gohsefimer® Z-200, manufactured by The Nippon Synthetic Chemical Industry Co., Ltd.), 3 parts of a 10 % aqueous solution of glyoxal and 120 parts of water.
  • a heat-sensitive recording material was prepared by applying to one side of a synthetic paper (trade name: Yupo® FPG-80, manufactured by Yupo Corporation) the heat-sensitive recording layer coating composition and the protective layer coating composition in such amounts that the respective amounts after drying would be 5g/m 2 and 3g/m 2 , and drying the resulting coating layers. After formation of the protective layer, the heat-sensitive recording material was subjected to a smoothing treatment by a supercalender.
  • a synthetic paper trade name: Yupo® FPG-80, manufactured by Yupo Corporation
  • a composition composed of 10 parts of 4,4'-dihydroxy-diphenylsulfone, 4 parts of a 10 % aqueous solution of sulfone-modified polyvinyl alcohol and 8 parts of a 5% aqueous solution of hydroxypropyl methylcellulose was pulverized by an Ultra Visco Mill (manufactured by Aymex Co.,Ltd.) to an average particle diameter of 1.5 ⁇ m, giving Dispersion H.
  • Dispersion I A commercially available stearic acid amide dispersion (trade name: Himicron® G-270, solids content: 21 %, manufactured by Chukyo Yushi Co., Ltd.) was used as Dispersion I.
  • Heat-sensitive recording materials were prepared in the same manner as in Example 1, except that the components and the proportions thereof were selected as shown in Table 1 instead of using 30 parts of Dispersion A, 30 parts of Dispersion B, 30 parts of Dispersion C, 30 parts of Dispersion D, 0.6 part of Dispersion E, 1.0 part of Dispersion F and 18 parts of Dispersion G.
  • Example 2 Dispersion A (30 parts) + Dispersion H (30 parts) Dispersion C (30 parts) + Dispersion D (30 parts) + Dispersion E (0.6 part) + Dispersion F (1 part) Dispersion G (18 parts)
  • Example 3 Dispersion A (20 parts) + Dispersion B (40 parts) Dispersion C (30 parts) + Dispersion D (30 parts) + Dispersion E (0.6 part) + Dispersion F (1 part) Dispersion G (18 parts)
  • Example 4 Dispersion A (40 parts) + Dispersion B (20 parts) Dispersion C (30 parts) + Dispersion D (30 parts) + Dispersion E (0.6 part) + Dispersion F (1 part) Dispersion G (18 parts)
  • Example 5 Dispersion A (30 parts) + Dispersion B (30 parts) Dispersion C (60 parts) + Dispersion E (0.6 parts) + Dispersion F (1 part) Dispersion G (18 parts)
  • Example 6 Dispersion A (30 parts) + Dispersion B (30 parts)
  • a heat-sensitive recording material was prepared in the same manner as in Example 1 except that 3-di (n-pentyl) amino-6-methyl-7-anilinofluoran was used in place of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran in the preparation of Dispersion C.
  • a heat-sensitive recording material was prepared in the same manner as in Example 1 except that 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluoran was used in place of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran in the preparation of Dispersion C.
  • a heat-sensitive recording material was prepared in the same manner as in Example 1 except that 3,3'-diallyl-4,4'-dihydroxy-diphenylsulfone was used in place of 2,4'-dihydroxy-diphenylsulfone in the preparation of Dispersion B.
  • a heat-sensitive recording material was prepared in the same manner as in Example 1 except that 1.0 part of Dispersion F was not used in the preparation of the heat-sensitive recording layer coating composition.
  • the heat-sensitive recording materials were subjected to a 17-step gradation recording by a Video Printer (trade name: UP-880, ® manufactured by Sony Corporation), and the density of each recorded portion was measured by a Macbeth densitometer (trade name: RD914, manufactured by Macbeth) in visual mode.
  • gradation index the difference in density between the recorded portion at Step 6 and the unrecorded portion is referred to as "gradation index”. According to the research done by the inventors, if the gradation index (difference in density between the recorded portion at Step 6 and the unrecorded portion) is about 0.3 ⁇ 0.1, excellent gradation is achieved.
  • Figure 1 is a graph showing the relationship between the intensity of the recording energy applied (energy applied by a Video Printer in the above 17-step gradation recording) and the density of the recorded portion with respect to the heat-sensitive recording materials of Example 1 and Comparative Example 3.
  • the heat-sensitive recording material of Comparative Example 3 which, unlike the present invention, contains only one kind of developer has a recording density of only about 0.19 at Step 6, and the gradation index (difference in density between the recorded portion at Step 6 and the unrecorded portion) is only 0.12. Further, compared to the low densities of the recorded portions up to Step 9, the densities of the recorded portions substantially increase after Step 9. As a result, when all 17 steps are considered, the graph showing the relationship between the intensity of the recording energy applied and the density of the recorded portions is not a straight line but a curved line, indicating an inferior gradation property.
  • the heat-sensitive recording material of Example 1 of the invention has a recording density of about 0.37 at Step 6, and the gradation index (difference in density between the recorded portion at Step 6 and the unrecorded portion is 0.29, which is within the difference in density range of 0.3 ⁇ 0.1.
  • the graph showing the relationship between the intensity of the recording energy applied and the density of the recorded portions is a substantially straight line, indicating an excellent gradation property.
  • the heat-sensitive recording materials of Examples 1 to 15 have saturation densities (maximum densities of the recorded portions) greater than those of the heat-sensitive recording materials of Comparative Examples.
  • the heat-sensitive recording material of the invention gives recorded portions having nearly achromatic black color, is excellent in density of recorded portions (recording sensitivity), gradation and background-fogging resistance, has high saturation density of the recorded portion (maximum density of recorded portion), and further has excellent heat resistance and moisture resistance, resulting in less change over time in density.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
EP02753221A 2002-05-14 2002-08-02 Thermal recording material Expired - Lifetime EP1504920B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2002137905 2002-05-14
JP2002137905 2002-05-14
PCT/JP2002/007912 WO2003095219A1 (fr) 2002-05-14 2002-08-02 Materiau d'enregistrement thermique

Publications (3)

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EP1504920A4 EP1504920A4 (en) 2005-02-09
EP1504920A1 EP1504920A1 (en) 2005-02-09
EP1504920B1 true EP1504920B1 (en) 2006-04-19

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EP (1) EP1504920B1 (ko)
KR (1) KR100609819B1 (ko)
CN (1) CN1292919C (ko)
DE (1) DE60210824T2 (ko)
WO (1) WO2003095219A1 (ko)

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US7582408B2 (en) * 2007-04-27 2009-09-01 Hewlett-Packard Development Company, L.P. Color forming compositions with a fluoran leuco dye having a latent developer
CN102433798A (zh) * 2011-09-29 2012-05-02 河南省江河纸业有限责任公司 能够防止含机浆/化机浆热敏纸褪色的热敏纸的制造方法
CN102807853B (zh) * 2012-08-10 2014-07-23 北京亚美方舟科贸有限公司 一种可逆热致变色性微胶囊及其制备方法
CN105200850A (zh) * 2015-09-18 2015-12-30 金华盛纸业（苏州工业园区）有限公司 一种无底涂的高防护性能热敏纸及其制造方法
DE102015119428B3 (de) * 2015-11-11 2016-03-24 Papierfabrik August Koehler Se Wärmeempfindliches Aufzeichnungsmaterial und Verfahren zu dessen Herstellung
CN108284677B (zh) * 2018-01-22 2020-08-14 河南卓立膜材料股份有限公司 一种热敏记录复合材料及其生产工艺

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KR20040044438A (ko) 2004-05-28
EP1504920A4 (en) 2005-02-09
EP1504920A1 (en) 2005-02-09
DE60210824D1 (de) 2006-05-24
WO2003095219A1 (fr) 2003-11-20
KR100609819B1 (ko) 2006-08-08
CN1538912A (zh) 2004-10-20
CN1292919C (zh) 2007-01-03
DE60210824T2 (de) 2006-11-30

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