JP5272573B2 - Transparent thermosensitive recording material and method for producing the same - Google Patents

Description

  The present invention relates to a transparent thermosensitive recording material utilizing a color development reaction between a leuco dye and a colorant, and a method for producing the same.

  A heat-sensitive recording material using a color reaction between a leuco dye and a colorant is relatively inexpensive, a recording device is compact, and its maintenance is easy, so a recording medium such as a facsimile, various computers, a CAD plotter, etc. In addition, it is also used as a recording medium for medical devices such as for ultrasonic image diagnosis, X-ray image diagnosis, and NMR tomographic image diagnosis.

  In particular, a thermal recording material for Saucusten, which is used for medical diagnosis, is required to have transparency, gradation of a transmission recording image, and high density.

  For this reason, a thermal recording medium for medical diagnosis is required to have a high maximum recording density, and in a region where the applied energy of the thermal head is high, recording failures such as sticking and noise are likely to occur during recording. From the viewpoint of solving such a recording failure, a protective layer is generally provided on the thermosensitive recording layer, but there is a problem that the recording sensitivity is lowered and it is difficult to obtain a high density.

  One way to improve the recording density of the thermal recording medium is to reduce the amount of adhesive in the thermal recording layer. However, the decrease in adhesive reduces the adhesion between the substrate and the thermal recording layer. However, the heat-sensitive recording layer may be easily peeled off from the base material, which is a particular problem for medical diagnosis applications in clean environments such as finishing processes and medical sites.

  A method for improving the adhesion to the substrate and the suitability of the Saucusten by providing an anchor coat layer between the substrate and the thermosensitive recording layer, and incorporating the water-dispersible adhesive and the blue pigment in the anchor coat layer (patent) Reference 1), having an anchor coat layer containing a hydrophobic resin, and containing the dialkyl sulfosuccinate in the anchor coat layer, it has excellent adhesion to the substrate and has no unevenness in the recorded image. Although a method for obtaining a recording material (see Patent Document 2) has been proposed, a method that completely satisfies the required characteristics has not been obtained.

JP-A-10-305660 JP 2005-74701 A

  An object of the present invention is to provide a transparent thermosensitive recording material that is excellent in adhesiveness with a transparent support and can obtain a high concentration, and a method for producing the same.

  As a result of intensive studies in view of the above-described conventional techniques, the inventor has found that the heat-sensitive recording layer adjacent to the anchor coat layer has a total solid content of the heat-sensitive recording layer adjacent to the anchor coat layer. The present inventors have found that the above-mentioned problems can be solved by containing 5 to 20% by mass based on the amount, and have intensively studied to complete the present invention. That is, the present invention relates to the following transparent thermosensitive recording material and a method for producing the same.

  Item 1: A transparent support in which an anchor coat layer containing a water-dispersible adhesive as a main component, at least one heat-sensitive recording layer containing a leuco dye and a colorant, and a protective layer are provided in this order on a transparent support. In the heat-sensitive recording material, the heat-sensitive recording layer adjacent to the anchor coat layer contains 5 to 20% by mass of a water-dispersible adhesive with respect to the total solid content of the heat-sensitive recording layer adjacent to the anchor coat layer. A transparent thermosensitive recording material.

  Item 2: The transparent thermosensitive recording material according to Item 1, wherein the anchor coat layer contains a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure containing a urethane resin component in at least one phase.

  Item 3: The transparent thermosensitive recording material according to Item 1 or 2, wherein the anchor coat layer contains a water-dispersible adhesive in an amount of 75 to 95% by mass with respect to the total solid content of the anchor coat layer.

  Item 4: The thermal recording layer adjacent to the anchor coat layer contains a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure containing a urethane resin component in at least one phase. The transparent thermosensitive recording material according to item 1.

  Item 5: A water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure in which a heat-sensitive recording layer provided on a heat-sensitive recording layer adjacent to the anchor coat layer contains a urethane resin component in at least one phase, Item 5. The transparent heat-sensitive recording material according to any one of Items 1 to 4, which is contained in an amount of 15 to 35% by mass relative to the total solid content of the heat-sensitive recording layer provided on the heat-sensitive recording layer adjacent to the coating layer.

  Item 6: A water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure in which an intermediate layer is provided between the thermosensitive recording layer and the protective layer, and the intermediate layer contains a urethane resin component in at least one phase, Item 6. The transparent thermosensitive recording material according to any one of Items 1 to 5, which is contained in an amount of 60 to 90% by mass relative to the total solid content of the intermediate layer.

  Item 7: The method for producing a transparent thermosensitive recording material according to any one of Items 1 to 6, wherein at least one heat-sensitive recording layer and a coating solution for an adjacent layer are applied simultaneously by a multi-layer coating method by a slide bead coating method. A method for producing a transparent thermal recording material, comprising drying and providing at least one thermal recording layer and an adjacent layer.

  The present invention provides a transparent thermosensitive recording material excellent in adhesion with a transparent support and capable of obtaining a high concentration and a method for producing the same, and a transparent thermosensitive recording material for medical diagnosis, particularly a transparent thermosensitive recording material for mammography diagnosis, etc. It can also be used.

  The anchor coat layer in the present invention contains a water dispersible adhesive as a main component and is provided on a transparent support. Examples of the water-dispersible adhesive include polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate ester, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer, and styrene-butadiene copolymer. Examples thereof include water-insoluble polymers such as polymers and styrene-butadiene-acrylic copolymers. The water-insoluble polymer may be used in a latex state. These water-dispersible adhesives can be used in combination.

In the present invention, from the viewpoint of improving adhesion to a transparent support and water resistance, the anchor coat layer contains a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure having a urethane resin component in at least one phase. The

  The heterogeneous particle structure of the polymer latex is not particularly limited. Structural examples and preparation methods of heterostructure particles are described in “Application of Synthetic Latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara Publishing Co., Ltd., published by Kobunshi Publishing Co., Ltd. (1993)). There are a shell structure, a composite structure, a localized structure, a daruma-like structure, a raspberry-like structure, a multiparticulate composite structure, a mizuzuki structure, an IPN (interpenetrating network structure), etc., but the present invention provides a core-shell structure, a composite structure, A raspberry-like structure and a multiparticulate composite structure are preferred, and in the preferred heterophasic particle structure of the polymer latex, it is more preferred to blend a urethane resin component at the center of the polymer latex.

  The polymer latex having a heterophasic particle structure used in the present invention includes, for example, natural rubber, polybutadiene, styrene-butadiene polymer, acrylonitrile-butadiene polymer, methyl methacrylate-butadiene polymer as components other than urethane resin, A latex containing polyacrylonitrile, polyvinyl acetate, polyethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polyvinyl chloride and the like. Examples of components other than urethane resins include styrene-butadiene polymers, acrylonitrile-butadiene polymers, and methyl methacrylate-butadiene polymers. 10-90 mass% is preferable and, as for the content rate of the urethane resin in the polymer latex of heterophase particle structure, 20-80 mass% is more preferable. Examples of the polymer latex having such a heterophasic particle structure include a resin obtained by polymerizing a styrene monomer and a butadiene monomer in an aqueous medium containing a polyurethane ionomer, and Patelacol H2090, H2020A, etc. (manufactured by DIC) It is commercially available in the state and can be easily obtained and used.

In the present invention, an anchor coat layer is water-dispersible adhesive, you containing 75 to 95 wt% based on the total solids content of the anchor coat layer. By setting it to 75% by mass or more, it is possible to obtain even better adhesion. On the other hand, application suitability can be imparted by adjusting the content to 95% by mass or less.

  The anchor coat layer can also contain a water-soluble adhesive as long as the effects of the present invention are not impaired. Examples of the water-soluble adhesive include polyvinyl alcohol and derivatives thereof, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, and acrylamide-acrylic acid. Examples thereof include ester copolymers, acrylamide-acrylic acid esters-methacrylic acid ester copolymers, styrene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, casein, gelatin, and derivatives thereof.

  In addition, surfactants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, fatty acid metal salts, and fluorine-based interfaces such as perfluoroalkylethylene oxide adducts as auxiliary agents for the anchor coat layer Activators, waxes such as polyethylene wax, carnauba wax, paraffin wax, ester wax, pigments such as kaolin, clay, talc, calcium carbonate, calcined kaolin, titanium oxide, amorphous silica, aluminum hydroxide, glyoxal, formalin, glycine, Glycidyl ester, glycidyl ether, dimethylol urea, ketene dimer, dialdehyde starch, melamine resin, polyamide resin, polyamide-epichlorohydrin resin, ketone-aldehyde tree , Borax, boric acid, ammonium zirconium carbonate, the crosslinking agent such as an epoxy compound, a defoaming agent, may be used a fluorescent dye, optionally a coloring dye.

The anchor coat layer uses water as a medium, and, for example, the coating amount for the anchor coat layer prepared by mixing the polymer latex having a different phase particle structure, polyvinyl alcohol, an auxiliary agent, and the like is 0. It is applied and dried on the transparent support so as to be about 5 to 5 g / m ² .

  The heat-sensitive recording layer in the present invention contains a leuco dye and a colorant and is provided on the anchor coat layer. Specific examples of leuco dyes include the following leuco dyes.

  3-diethylamino-7-chlorofluorane, 3- (N-ethyl-Np-tolylamino) -7-methylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (N-ethyl) -N-isoamylamino) -7-phenoxyfluorane, 3-diethylamino-6,8-dimethylfluorane, 3-di (n-butyl) amino-6-methyl-7-bromofluorane, 3,3-bis Red color-forming leuco dyes such as (1-n-amyl-2-methylindol-3-yl) phthalide and 3-di (n-butyl) amino-7-chlorofluorane.

  3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methyl) Phenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl)- 4-Azaphthalide, 3-diphenylamino-6-diphenylaminofluorane, 3- (2-methyl-1-n-octylindol-3-yl) -3- (4-diethylamino-2-ethoxyphenyl) -4- Blue coloring leuco dyes such as azaphthalide.

  3- (N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3- (N-ethyl-Nn-hexylamino) -7-anilinofluorane, Green coloring leuco dyes such as 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3,6-dimethoxyfluorane, 1- (4-n-dodecyloxy- Yellow color-forming leuco dyes such as 3-methoxyphenyl) -2- (2-quinolyl) ethylene and 1,3,3-trimethylindoline-2,2′-spiro-6′-nitro-8′-methoxybenzopyran.

  3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (m-trifluoromethylanilino ) Fluorane, 3- (N-isoamyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-di (n-butyl) amino -6-methyl-7-anilinofluorane, 3-di (n-amyl) amino-6-methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethylamino) -6-methyl -7-anilinofluorane, 3- (Nn-hexyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-di (n-butyl) amino- (2-chloroanilino) fluorane 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (3-toluidino) fluorane, 3-diethylamino-6-methyl-7- (2,6-dimethylani Black color-forming leuco dyes such as lino) fluorane, 3-diethylamino-6-methyl-7- (2,4-dimethylanilino) fluorane;

  Although the usage-amount of a leuco dye is not specifically limited, About 5-30 mass% is preferable with respect to the total solid of a heat-sensitive recording layer.

  The leuco dye in the present invention can be contained in the heat-sensitive recording layer in the form of solid fine particles wet-micronized by a sand mill together with protective colloidal substances such as polyvinyl alcohol and methyl cellulose, but contains a leuco dye and a hydrophobic resin. The composite particles are preferably used in the form in which they are formed. Here, the leuco dye is “a form in which composite particles containing a leuco dye and a hydrophobic resin are formed”. For example, (1) one or more leuco dyes are described in JP-A-60-244594. (2) One or more leuco dyes contained in a hydrophobic resin matrix made of polyisocyanate by the method described in JP-A-9-263057, (3 ) A form in which a compound having an unsaturated carbon bond is polymerized on the surface of fine particles of one or more leuco dyes by the method described in JP-A No. 2000-158822. The leuco dyes in these composite particles are highly separable from the outside, less subject to background fogging due to heat and humidity and decoloration of color images. Furthermore, in the forms (1) and (2), the leuco dye is an isocyanate or an organic solvent. Therefore, the transparency of the heat-sensitive recording layer is also superior to the case where the leuco dye is used in a solid fine particle state.

  The content of the leuco dye in the composite particles is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and further preferably about 25 to 50% by mass with respect to the total solid content of the composite particles.

  Although it does not specifically limit as hydrophobic resin which forms a composite particle, For example, urea type resin, urethane type resin, urea-urethane type resin, styrene type resin, acrylic resin etc. are mentioned. Among these, urea resins and urea-urethane resins are preferable because they are excellent in heat-resistant background fogging.

  When preparing composite particles in which a leuco dye is dispersed in a urea resin or a urea-urethane resin, for example, an oily solution in which a polyvalent isocyanate compound and a leuco dye are dissolved is used as a hydrophilic protective colloid such as polyvinyl alcohol. The solution is emulsified and dispersed so that the volume average particle diameter is preferably about 0.5 to 3 μm, more preferably about 0.5 to 1.5 μm, and a reactive substance such as polyethyleneimine or polyamine is further added if necessary. After mixing, the emulsion dispersion is heated to accelerate the polymerization reaction of the polyvalent isocyanate compound.

  The polyisocyanate compound is a compound that forms polyurea or polyurea-polyurethane by reacting with water, and may be a polyisocyanate compound alone, or a polyisocyanate compound and a polyol or polyamine that reacts with the polyisocyanate compound. Or a multimer such as an adduct of a polyvalent isocyanate compound and a polyol, a biuret of a polyvalent isocyanate compound, or an isocyanurate.

  Specific examples of the polyvalent isocyanate compound include, for example, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate. 1,3-bis (isocyanatomethyl) cyclohexane, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate, tetramethylxylylene diisocyanate, 4,4′-diphenylpropane diisocyanate , Hexamethylene diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4 ′, 4 ″ -triphenylmeta Examples include triisocyanate, toluene-2,4,6-triisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of 2,4-tolylene diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, and the like. It is done.

  Specific examples of the polyol compound include, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, and 1,3-dihydroxybutane. 2,2-dimethyl-1,3-propanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, phenylethylene glycol, penta Erythritol, 1,4-di (2-hydroxyethoxy) benzene, 1,3-di (2-hydroxyethoxy) benzene, p-xylylene glycol, m-xylylene glycol, 4,4′-isopropylidene diphenol, 4,4'-dihydroxydi Enirusuruhon, and the like.

  Specific examples of the polyamine compound include, for example, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, 2,5-dimethylpiperazine, triethylenetriamine, triethylene Examples include ethylenetetramine and diethylaminopropylamine.

  Of course, the polyvalent isocyanate compound, the adduct of polyvalent isocyanate and polyol, the polyol compound, and the like are not limited to the above compounds, and two or more kinds may be used in combination as necessary.

  Further, the composite particles have an ultraviolet absorption such as an aromatic organic compound (sensitizer) having a melting point of about 40 to 150 ° C. for increasing the recording sensitivity and 2-hydroxy-4-octyloxybenzophenone for increasing the light resistance. A hindered phenol, a hindered amine, etc. can also be contained as an agent and a stabilizer.

  The content of the composite particles is preferably about 10 to 60% by mass, more preferably about 20 to 50% by mass with respect to the total solid content of the thermosensitive recording layer. The ratio of the composite particles to the colorant is preferably about 50 to 300 parts by mass, more preferably about 100 to 250 parts by mass with respect to 100 parts by mass of the composite particles.

  Specific examples of the colorant include, for example, 4,4′-isopropylidenediphenol, 4,4′-cyclohexylidenediphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,4 '-Dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'- Allyloxydiphenyl sulfone, 4-hydroxy-4′-methyldiphenyl sulfone, butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, 1,1-bis (4-hydroxyphenyl) -1- Phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxy Phenyl) ethyl] benzene, 2-[(4-hydroxyphenyl) methyl] -6-[(2-hydroxyphenyl) methyl] -4- (sec-butyl) phenol, 2,6-bis [(4-hydroxyphenyl) ) Methyl] -4- (sec-butyl) phenol and other phenolic compounds, Np-tolylsulfonyl-N′-phenylurea, 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) Ureido] sulfonyl and ureido groups in the molecule such as diphenylsulfone, 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane, Np-tolylsulfonyl-N′-p-butoxyphenylurea 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid zinc, 4- [3 (P- tolylsulfonyl) propyloxy] salicylate, zinc 5- [p- (2-p- methoxyphenoxy ethoxy) cumyl] zinc salt compound of aromatic carboxylic acids such as salicylic acid, and the like. In addition, about 1-8 mass parts is preferable with respect to 1 mass part of leuco dyes, and, as for the usage-amount of a coloring agent, about 2-7 mass parts is more preferable.

  In the present invention, the heat-sensitive recording layer adjacent to the anchor coat layer contains a water-dispersible adhesive in an amount of 5 to 20% by weight, preferably 10 to 15% by weight, based on the total solid content of the heat-sensitive recording layer. By setting the content to 5% by mass or more, good adhesion can be exhibited, and further, an effect of reducing the background fogging and suppressing the surface roughness of the recording portion generated in a high energy region can be obtained. On the other hand, by setting it to 20% by mass or less, a high recording density of 3.6 or higher required for medical diagnosis such as mammography can be achieved, and a high density of saturation density 4.0 can be obtained. Further, by improving the maximum recording density by increasing the energy applied to the thermal head, it is possible to obtain an effect excellent in gradation reproducibility on the high density side.

  The heat-sensitive recording layer preferably contains a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure having a urethane resin component in at least one phase. Thereby, the usage-amount of a water-dispersible adhesive agent can be suppressed and adhesiveness and a recording density can be improved. Such a water-dispersible adhesive obtained from latex can be appropriately selected from those used for the anchor coat layer described above.

  In the present invention, a thermal recording layer may be further provided on the thermal recording layer adjacent to the anchor coat layer. In this case, the heat-sensitive recording layer provided on the heat-sensitive recording layer adjacent to the anchor coat layer is provided with a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure having a urethane resin component in at least one phase. It is preferable to contain 15 to 35 mass% with respect to the total solid content of the adjacent heat-sensitive recording layer. Thereby, the recording density can be improved while maintaining the adhesion.

  As long as the effects of the present invention are not impaired, any one of a water-soluble adhesive and a water-dispersible adhesive contained in the anchor coat layer can be used for the heat-sensitive recording layer. .

  If necessary, the thermosensitive recording layer may contain a storability improving agent for enhancing the storability of the recording part. Specific examples of the preservability improver include, for example, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane and 1,1,3-tris (2-methyl-4-hydroxy-). 5-tert-butylphenyl) butane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2′-ethylidenebis (4,6-di-tert-butylphenol), 1,4-bis [Α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 4,4′-thiobis (2- Hindered fe such as methyl-6-tert-butylphenol), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, 4- (2-ethyl-1,2-epoxyethyl) diphenylsulfone, 4-benzyloxy-4 ′-(2,3 -Diphenylsulfone-based epoxy compounds such as glycidyloxy) diphenylsulfone; UV absorbers such as 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2-hydroxy-4-benzyloxybenzophenone .

  If necessary, the heat-sensitive recording layer may contain a sensitizer for increasing the recording sensitivity. Specific examples of the sensitizer include stearamide, 1,2-di (3-methylphenoxy) ethane, 1,2-phenoxyethane, parabenzylbiphenyl, naphthylbenzyl ether, benzyl-4-methylthiophenyl ether, Examples include 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid-di-p-chlorobenzyl ester, terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, and isophthalic acid dibutyl ester.

  Furthermore, auxiliary agents such as perfluoroalkylethylene oxide adducts used in the anchor coat layer can be used in the heat-sensitive recording layer as necessary.

The heat-sensitive recording layer contains water as a medium, for example, a leuco dye formed into composite particles, or a leuco dye and a colorant having an average particle diameter of about 0.2 to 1.0 μm, and if necessary, a storage stability improver. The coating amount for the heat-sensitive recording layer prepared by mixing a dispersion liquid such as a sensitizer, a water-dispersible adhesive, and an auxiliary agent is about 3 to 30 g / m ² after drying. Thus, it is provided by applying and drying on the anchor coat layer.

In the present invention, Ru an intermediate layer between the thermosensitive recording layer and the protective layer. Thereby, transparency and water resistance can be further improved. Further intermediate layer, a water-dispersible adhesive obtained from a polymer latex of heterogeneous phase particle structure having a urethane resin component in at least one phase, you containing 60 to 90 wt% based on the total solids content of the intermediate layer. Thereby, the recording density can be improved while maintaining the adhesion.

  As long as the effects of the present invention are not impaired, any of a water-soluble adhesive and a water-dispersible adhesive contained in the anchor coat layer can be used for the intermediate layer, as long as the adhesive is not impaired. Furthermore, an auxiliary agent such as a perfluoroalkylethylene oxide adduct used for the anchor coat layer can be used in the intermediate layer as necessary.

The intermediate layer uses water as a medium, for example, a coating liquid for intermediate layer prepared by mixing a water-dispersible adhesive and, if necessary, an auxiliary agent, the coating amount after drying is 0.5 to 10 g / such that m ² approximately, is provided by coating and drying a heat-sensitive recording layer.

  The protective layer in the present invention is provided on the heat-sensitive recording layer or an intermediate layer provided as necessary. Kaolin, aluminum hydroxide, calcined kaolin, colloidal silica, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, barium sulfate, talc, styrene resin filler, nylon resin filler, urea / formalin resin A pigment such as a filler can be contained. Among these, it is preferable to contain calcined kaolin together with at least one selected from kaolin and aluminum hydroxide from the viewpoint of suppressing residue adhesion to the thermal head. The content of the calcined kaolin is preferably about 0.3 to 5% by mass, more preferably about 0.5 to 3% by mass with respect to the total solid content of the protective layer. Moreover, the total amount of the pigment with respect to the total solid amount of the protective layer is preferably about 5 to 35% by mass.

  For the protective layer, any one of a water-soluble adhesive and a water-dispersible adhesive contained in the anchor coat layer can be used. Among these adhesives, a specific polyvinyl alcohol consisting of at least one selected from acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol and silicon-modified polyvinyl alcohol is preferable, and acetoacetyl-modified polyvinyl alcohol is more preferable. . In addition, it is particularly preferable to use a resin obtained from such specific polyvinyl alcohol and urethane latex in combination because a protective layer having excellent film forming properties can be obtained. In addition, 40-90 mass% is preferable with respect to the total solid amount of a protective layer, and, as for the usage-amount of an adhesive agent, 55-85 mass% is more preferable.

  Examples of the resin obtained from such urethane latex include a polyester polyurethane resin having a softening point of 80 ° C. or higher, a polyether polyurethane resin, and an aliphatic polyurethane resin. In addition, although it does not specifically limit about the usage rate of resin obtained from specific polyvinyl alcohol and urethane type latex, Preferably it is 10-100 mass parts with respect to 100 mass parts of specific polyvinyl alcohol, More preferably Can use a resin obtained from 20 to 70 parts by mass of urethane latex.

  Furthermore, as protective agents for the protective layer, lubricants such as alkyl phosphates, stearamide, zinc stearate, calcium stearate, crosslinks such as boric acid, borax, dialdehyde starch, polyamide epichlorohydrin resin, adipic acid dihydrazide Surfactants such as agents, dialkyl sulfosuccinates, alkyl sulfonates, alkyl carboxylates, alkyl ethylene oxides, and fluorosurfactants such as perfluoroalkyl ethylene oxide adducts can also be used.

The protective layer is generally prepared by mixing water as a medium, for example, a water-soluble adhesive such as polyvinyl alcohol, a resin obtained from urethane latex, a pigment, and if necessary, a crosslinking agent, a lubricant, and a surfactant. the protective layer coating composition, the order of coating amount of 0.5 to 10 g / ^{m 2} after drying, preferably such that 1 to 5 g / ^{m 2} approximately, the heat-sensitive recording layer or as needed provided intermediate layer Applied and dried.

  Each of the above coating liquids is applied by, for example, die coating, air knife coating, rod blade coating, bar coating, varibar blade coating, pure blade coating, short dwell coating, slot coating, extrusion coating, curtain coating, slide coating, etc. Is applied. Each coating solution may be applied and dried one layer at a time, or the same coating solution may be applied in two or more layers. Furthermore, two or more layers can be applied simultaneously. As the simultaneous multilayer coating method, a slide bead coating method, a bead coating method using a multilayer slot die, a slide curtain coating method, a curtain coating method using a multilayer slot die and the like are preferably used. Here, the simultaneous multilayer coating is a method in which two or more layers are coated at the same time, and includes a method in which the upper layer is coated without drying after the lower layer is coated.

  In the present invention, it is preferable to provide at least one heat-sensitive recording layer and an adjacent layer by simultaneously applying and drying at least one heat-sensitive recording layer and an adjacent layer coating solution by a slide bead coating method. Thereby, it can suppress that a bubble etc. mix between a thermosensitive recording layer and the adjacent layer, and can improve transparency and recording density further. Further, a low coating amount of an anchor coat layer, a protective layer, or the like can be applied as a wet coating amount in total with the heat-sensitive recording layer, thereby facilitating leveling of the coating liquid, reducing coating defects, and improving productivity. Furthermore, the shearing force applied at the time of application of the coating liquid can be reduced, and the effects of the present invention can be sufficiently exhibited without impairing the stability of the water-dispersible adhesive.

  Specific examples of the combination of layers in the case of simultaneous multilayer coating are not particularly limited. For example, a combination of an undercoat layer and a thermal recording layer, a combination of a thermal recording layer and a protective layer, a combination of an undercoat layer, a thermal recording layer and a protective layer. And a combination of two or more different heat-sensitive recording layers, a combination of a heat-sensitive recording layer, an intermediate layer and a protective layer, a combination of an undercoat layer, a heat-sensitive recording layer, an intermediate layer and a protective layer.

  Examples of the transparent support include a polyethylene terephthalate film (PET film), a polypropylene film, a polystyrene film, and a vinyl chloride film. Among these, a heat-resistant polyethylene terephthalate film is preferable for a transparent thermosensitive recording material for medical diagnosis that requires recording in a high energy region. The transparent support has a thickness of about 30 to 300 μm, may be colored blue, and preferably has a haze value of 10% or less. The surface of the transparent support may be subjected to corona discharge treatment prior to application of the anchor coat layer coating solution, or may be subjected to conductive treatment with a conductive agent. Further, a reverse layer containing a pigment such as resin particles and an adhesive may be provided on the opposite surface of the heat-sensitive recording layer in order to improve the runnability of the transparent heat-sensitive recording material.

  In the present invention, the heat-sensitive recording layer is a multicolor heat-sensitive recording layer, a glossy layer cured by irradiating ultraviolet rays or an electron beam on the protective layer, or a smoothing process using a super calendar. Various known techniques in the body manufacturing field can be added as necessary.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”, respectively. The average particle size of the composite particles and pigment used in the examples and comparative examples was measured using a laser diffraction particle size distribution analyzer SALD2000 (manufactured by Shimadzu Corporation). Measured using a mechanical light scattering particle size distribution analyzer LB-500 (manufactured by Horiba, Ltd.).

Example 1
-Preparation of composite particle dispersion (liquid A) 15 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane as leuco dye and 3,3-bis (4-diethylamino-2-) (Ethoxyphenyl) -4-azaphthalide (3 parts) and 2-hydroxy-4-octyloxybenzophenone (5 parts), dicyclohexylmethane-4,4′-diisocyanate (manufactured by Sumitomo Bayer Urethane, Desmodur W), m- Heat-dissolve (150 ° C.) in a mixed solvent consisting of 10 parts of tetramethylxylylene diisocyanate (manufactured by Mitsui Takeda Chemical Co., Ltd., TMXDI), and this solution is combined with 9 parts of polyvinyl alcohol (Kuraray Co., Ltd., Poval PVA-217EE) and surface activity. As an agent, an ethylene oxide adduct of acetylene glycol (manufactured by Nissin Chemical Industry Co., Ltd. ) Was added slowly to the aqueous solution 100 parts containing 2 parts, using a homogenizer, was emulsified and dispersed by agitation speed 10000 rpm. To this emulsified dispersion, an aqueous solution in which 30 parts of water and 1.5 parts of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP006) were dissolved in 22.5 parts of water was added and homogenized. The emulsified dispersion was heated to 75 ° C. and subjected to a polymerization reaction for 6 hours to prepare a composite particle dispersion having an average particle size of 0.8 μm. In addition, it diluted with water so that a composite particle dispersion liquid might be 25%.

Preparation of composite particle dispersion (liquid B) 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane and 3,3-bis (4-diethylamino-2-) as leuco dye Ethoxyphenyl) -4-azaphthalide (2.5 parts) and 2-hydroxy-4-octyloxybenzophenone (3 parts), hexamethylene diisocyanate isocyanurate (D170HN, manufactured by Mitsui Takeda Chemical Co., Ltd.), m-tetramethyl Heat-dissolve (150 ° C.) in a mixed solvent consisting of 5 parts of xylylene diisocyanate (manufactured by Mitsui Takeda Chemical Co., Ltd., TMXDI), and use 9 parts of polyvinyl alcohol (Kuraray Co., Poval PVA-217EE) as a surfactant. 2 parts of ethylene oxide adduct of acetylene glycol (manufactured by Nissin Chemical Co., Ltd., Olphine E1010) The mixture was gradually added to 100 parts of the aqueous solution, and emulsified and dispersed by stirring at a rotational speed of 10,000 rpm using a homogenizer. To this emulsified dispersion, an aqueous solution in which 30 parts of water and 1.5 parts of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP006) were dissolved in 22.5 parts of water was added and homogenized. The emulsified dispersion was heated to 75 ° C. and subjected to a polymerization reaction for 6 hours to prepare a composite particle dispersion having an average particle size of 0.8 μm. The composite particle dispersion was adjusted to 25%.

-Preparation of colorant dispersion (liquid C) 42 parts of 4,4'-cyclohexylidene diphenol, 60 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol (trade name: Gocelan L3266, manufactured by Nippon Synthetic Chemical Industry), and A composition consisting of 18 parts of water was pulverized with an ultra visco mill until the average particle size became 0.3 μm to obtain a colorant dispersion.

Preparation of coating solution I for heat sensitive recording layer 100 parts of liquid A, 140 parts of liquid C, polymer latex of different phase particle structure containing urethane resin component in at least one phase (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration 41%) 25 parts, a composition comprising 0.8 part of a 10% aqueous solution of perfluoroalkylethylene oxide adduct [Surflon (registered trademark) S-145, manufactured by Seimi Chemical Co., Ltd.] and 100 parts of water was mixed. A coating solution was obtained.

Preparation of coating liquid II for heat-sensitive recording layer 100 parts of liquid B, 140 parts of liquid C, polymer latex having a different phase particle structure containing urethane resin component in at least one phase (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration 41%) 65 parts, a composition comprising 0.8 part of a 10% aqueous solution of perfluoroalkylethylene oxide adduct [Surflon (registered trademark) S-145, manufactured by Seimi Chemical Co., Ltd.] and 100 parts of water was mixed. A coating solution was obtained.

-Preparation of anchor coat layer coating solution 200 parts of polymer latex (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration 41%) having a different phase particle structure containing a urethane resin component in at least one phase, completely saponified polyvinyl alcohol A composition comprising 200 parts of a 10% aqueous solution, 0.5 part of a 10% aqueous solution of a perfluoroalkylethylene oxide adduct [Surflon (registered trademark) S-145, manufactured by Seimi Chemical Co., Ltd.] and 110 parts of water was mixed and stirred to anchor coat. A layer coating solution was obtained.

-Preparation of coating solution for intermediate layer 200 parts of a polymer latex having a different phase particle structure containing a urethane resin component in at least one phase (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration 41%), fully saponified polyvinyl alcohol 10 A composition comprising 200 parts of a 100% aqueous solution, 2.6 parts of a perfluoroalkylethylene oxide adduct [Surflon (registered trademark) S-145, manufactured by Seimi Chemical Co., Ltd.] and 110 parts of water was mixed and mixed. A liquid was obtained.

-Preparation of coating solution for protective layer Ionomer type urethane resin latex [manufactured by DIC, Hydran (registered trademark) AP-30F, solid concentration 20%] 100 parts, acetoacetyl-modified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry Co., Ltd., GO Cephimer (registered trademark) Z-410, polymerization degree: about 2300, saponification degree: about 98 mol%] 8% aqueous solution 500 parts, kaolin (manufactured by Engelhard, UW-90) with an average particle size of 1.6 μm 50 parts of 60% slurry atomized so as to become 2 parts of 40% slurry of calcined kaolin (Engelhard, Ansilex 93) having an average particle size of 2.5 μm, stearamide (manufactured by Chukyo Yushi Co., Ltd., Himicron) L-271, solid concentration 25%) 26 parts, stearyl phosphate potassium salt (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., Wopol 1800, solid Concentration 35%) 4 parts, a composition comprising 15 parts of a 10% aqueous solution of perfluoroalkylethylene oxide adduct [Surflon (registered trademark) S-145, manufactured by Seimi Chemical Co., Ltd.] and 300 parts of water is used for the protective layer. A coating solution was obtained.

・ Preparation of transparent thermosensitive recording material On one side of a blue transparent polyethylene terephthalate film (trade name: Melinex 912, thickness 175 μm, manufactured by Teijin DuPont), the coating solution for the anchor coat layer and the coating solution for the thermosensitive recording layer are formed from the support side. I, the heat-sensitive recording layer coating solution II, the intermediate layer coating liquid, in the order of protective layer coating liquid, each coating amount after drying ^{1.0g / m 2, 15g / m} 2, 7g / m 2, 3. Five layers were simultaneously applied and dried by a slide bead coating method using a slide bead coater so as to be 0 g / m ² and 1.5 g / m ² to obtain a transparent thermosensitive recording material.

Example 2
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, 25 parts of a polymer latex having a different phase particle structure containing at least one urethane resin component (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration: 41%) A transparent thermosensitive recording material was obtained in the same manner as in Example 1 except that the amount was changed to 15 parts.

Example 3
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, 25 parts of a polymer latex having a different phase particle structure containing at least one urethane resin component (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration: 41%) A transparent thermosensitive recording material was obtained in the same manner as in Example 1 except that the amount was changed to 45 parts.

Example 4 (Reference Example)
In the production of the transparent thermosensitive recording material of Example 1, the thermosensitive recording coating solution II and the intermediate layer coating solution were not used, and the anchor coat layer, the thermosensitive recording layer coating solution I, and the protective layer coating solution were used from the support side. In the same manner as in Example 1 except that three layers were simultaneously applied and dried so that the coating amounts after drying were 1.0 g / m ² , 15 g / m ² , and 3.5 g / m ² , respectively. A transparent thermosensitive recording material was obtained.

Comparative Example 1
In the production of the transparent thermosensitive recording material of Example 1, the anchor coating layer coating solution is not used, and the thermal recording layer coating solution I, the thermal recording layer coating solution II, the intermediate layer coating solution, and the protective layer are used from the support side. A transparent thermosensitive recording material was obtained in the same manner as in Example 1 except that the four coating layers were coated simultaneously and dried in the order of the coating solution.

Comparative Example 2
In the preparation of coating solution I for heat-sensitive recording layer of Example 1, 25 parts of a polymer latex having a different phase particle structure containing at least one urethane resin component (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration: 41%) In the production of a transparent thermosensitive recording material, the undercoat layer coating solution is not used, and the thermal recording layer coating solution I, the thermal recording layer coating solution II, and the intermediate layer coating solution are used from the support side. A transparent thermosensitive recording material was obtained in the same manner as in Example 1 except that the four coating layers were simultaneously applied and dried in the order of the coating solution for the protective layer.

Comparative Example 3
In the preparation of coating solution I for heat-sensitive recording layer of Example 1, 25 parts of a polymer latex having a different phase particle structure containing at least one urethane resin component (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration: 41%) A transparent thermosensitive recording material was obtained in the same manner as in Example 1 except that was changed to 75 parts.

Comparative Example 4
In the production of the transparent thermosensitive recording material of Example 1, the anchor coating layer coating solution, the thermal recording coating solution II, and the intermediate layer coating solution were not used, and the thermal recording layer coating solution I and protective layer were used from the support side. in the order of the coating liquid, 15 g / m ^2, so that 3.5 g / m ^2, except that simultaneous multilayer coating and drying the two layers, to obtain a transparent heat-sensitive recording layer in example 1.

Comparative Example 5
In the preparation of coating solution I for heat-sensitive recording layer of Example 1, 25 parts of a polymer latex having a different phase particle structure containing at least one urethane resin component (trade name: Pateracol H2020A, manufactured by DIC, solid content concentration: 41%) In the production of a transparent thermosensitive recording material, the coating solution for anchor recording layer, the thermosensitive recording coating solution II, and the coating solution for intermediate layer are not used, and the thermosensitive recording layer coating solution I is applied from the support side. , so that the order of protective layer coating liquid 15 g / m ^2, and 3.5 g / m ^2, except that simultaneous multilayer coating and drying the two layers, to obtain a transparent heat-sensitive recording layer in example 1 .

  The transparent thermosensitive recording material thus obtained was evaluated as follows. The results are shown in Table 1.

(Recording density)
Using a thermal recording printer UP-DF500 (manufactured by Sony Corporation), a transparent thermal recording medium is printed in a gradation mode in a gradation mode under a temperature of 23 ° C. and a humidity of 40% RH. The density of the recording part of the eye and the 16th gradation was measured. The density of the recording part was measured in a visual mode of a Macbeth densitometer (trade name: TR-927J type, manufactured by Macbeth). The highest recording density of the 16th gradation is excellent at 3.6 or higher.

(Saturated concentration)
Using a thermal gradient tester (TYPE HG-100, manufactured by Toyo Seiki Co., Ltd.), the transparent thermosensitive recording medium was colored by changing the temperature under the conditions of a load of 1 kgf / cm ² and an application time of 5 seconds. The saturation concentration was evaluated by measuring in a visual mode of a densitometer (trade name: TR-927J type, manufactured by Macbeth Co.).

(Adhesion)
By peeling the transparent thermosensitive recording material, peeling of the coating layer from the transparent support was visually evaluated. What peels off the coating layer is a practical problem.
○: No peeling of the coating layer.
(Triangle | delta): Although peeling of an application layer does not arise, the bent part turns white.
X: Peeling of the coating layer occurs.

  A transparent thermosensitive recording medium comprising an anchor coat layer containing a water-dispersible adhesive as a main component, at least one thermosensitive recording layer containing a leuco dye and a colorant, and a protective layer in this order on a transparent support. The heat-sensitive recording layer adjacent to the anchor coat layer contains a water-dispersible adhesive in an amount of 5 to 20% by mass based on the total solid content of the heat-sensitive recording layer adjacent to the anchor coat layer. And a method for producing the same can be provided, and can also be used for a transparent thermosensitive recording material for medical diagnosis, particularly a transparent thermosensitive recording material for mammography diagnosis.

Claims (2)

A transparent thermosensitive recording medium comprising an anchor coat layer containing a water-dispersible adhesive as a main component, at least one thermosensitive recording layer containing a leuco dye and a colorant, and a protective layer in this order on a transparent support. In the heat-sensitive recording layer adjacent to the anchor coat layer, a water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure containing a urethane resin component in at least one phase is used as the heat-sensitive recording layer adjacent to the anchor coat layer. A water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure containing 5 to 20% by mass with respect to the total solid content , wherein the anchor coat layer contains a urethane resin component in at least one phase. 75 to 95% by mass with respect to the total solid content, an intermediate layer is provided between the thermosensitive recording layer and the protective layer, and the intermediate layer is small. Both transparent heat-sensitive, characterized in that the water-dispersible adhesive obtained from a polymer latex of heterogeneous phase particle structure containing a urethane resin component in one phase, containing 60 to 90 wt% based on the total solid amount of the intermediate layer Recorded body. A water-dispersible adhesive obtained from a polymer latex having a heterophasic particle structure in which a heat-sensitive recording layer provided on a heat-sensitive recording layer adjacent to the anchor coat layer contains a urethane resin component in at least one phase is applied to the anchor coat layer. The transparent thermosensitive recording material according to claim 1, wherein the transparent thermosensitive recording material is contained in an amount of 15 to 35% by mass based on the total solid content of the thermosensitive recording layer provided on the adjacent thermosensitive recording layer.