JP2010058307A - Heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material having excellent water resistant strength in the heat-sensitive recording material provided with a heat-sensitive recording layer colored by heat on a support. <P>SOLUTION: Provided is the heat-sensitive recording material provided with the heat-sensitive recording layer colored by heat on the support, wherein water resistant strength is excellent by incorporating a resin having a reactive carbonyl on a side chain and a polyfunctional semi-carbazide compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat-sensitive recording material provided with a heat-sensitive recording layer that develops color by heat on a support, and has excellent water resistance.

  In general, a heat-sensitive recording material is provided with a heat-sensitive recording layer that develops color by heat on a support. By heating with a thermal head, a thermal pen, a laser, or the like, the electron-donating compound that is a dye precursor and a developer are developed. A recorded image can be obtained by an instantaneous reaction with an electron accepting compound as an agent. Such a heat-sensitive recording material has advantages such as that recording can be obtained with a relatively simple device, easy maintenance, no noise generation, etc., measurement recorder, facsimile, printer, computer terminal, It is used in a wide range of fields such as label printing machines, boarding tickets, and ticket issuing machines.

  In addition, as the applications of such heat-sensitive recording materials are diversified, many applications have been printed. In recent years, there has been a strong demand for heat-sensitive recording materials with surface strength suitable for printing in the market, and heat-sensitive recording materials with a protective layer that has excellent barrier properties that do not cause background coloring such as background fogging with printing solvents. Yes.

  Furthermore, recently, with the development of recording systems, the usage environment of thermal recording materials has shifted to harsher, especially when used in an environment exposed to moisture adhesion, which is excellent in water resistance. Is strongly desired.

Water resistance strength can be imparted to the thermosensitive recording material mainly by making the outermost layer water resistant. In other words, in the thermosensitive recording material having a protective layer on the thermosensitive recording layer, the protective layer that is the outermost layer is water-resistant, and in the thermosensitive recording material that does not have the protective layer, the thermosensitive recording layer that is the outermost layer is water-resistant. Need to do. In Patent Document 1, it is proposed to make the protective layer water resistant using a diacetone-modified polyvinyl alcohol as an adhesive and a hydrazine-based compound, particularly a carboxylic acid dihydrazide compound, as a water-resistant agent. In Patent Document 2, it is proposed that the protective layer contains polyvinyl alcohol having a reactive carbonyl group, a hydrazide compound as a crosslinking agent, and a basic filler for improving the stability of the coating liquid for the protective layer. Yes. On the other hand, Patent Document 3 proposes water resistance of the thermosensitive recording layer by a combination of diacetone-modified polyvinyl alcohol, a polyamidoamine / epichlorohydrin resin, and a carboxylic acid dihydrazide compound. In addition to these, as a method for making the heat-sensitive recording material water-resistant, a combination of various resins and a water-proofing agent / crosslinking agent is known, but it is still insufficient and further improvement is desired.
JP 11-314457 A JP 2002-283717 A JP 2002-127601 A

  An object of the present invention is to provide a heat-sensitive recording material having excellent water resistance.

  As a result of intensive studies, the present inventors have invented a heat-sensitive recording material that can solve the problem. That is, the heat-sensitive recording material of the present invention contains a resin having a reactive carbonyl group in the side chain and a polyfunctional semicarbazide compound in a heat-sensitive recording material provided with a heat-sensitive recording layer that develops color by heat on a support. It is a heat-sensitive recording material characterized.

  Further, a polyfunctional semicarbazide compound is contained in the heat-sensitive recording layer. Furthermore, a protective layer is provided on the thermosensitive recording layer, and a polyfunctional semicarbazide compound is contained in the protective layer.

  Further, the heat-sensitive recording material is characterized in that the resin having a reactive carbonyl group in the side chain is diacetone-modified polyvinyl alcohol. The heat-sensitive recording material is characterized in that the polyfunctional semicarbazide compound is burette litri (hexamethylene semicarbazide).

  According to the present invention, a heat-sensitive recording material having excellent water resistance can be provided.

  The heat-sensitive recording material of the present invention is a heat-sensitive recording material provided with a heat-sensitive recording layer that develops color by heat on a support, and has a protective layer on the heat-sensitive recording layer, and an intermediate layer between the support and the heat-sensitive recording layer. And those having a back coat layer on the opposite surface of the support on which the thermosensitive recording layer is provided. In the present invention, the location of the resin having a reactive carbonyl group in the side chain and the polyfunctional semicarbazide compound is within the range of the effect of increasing the water resistance of the thermosensitive recording material, the support, the thermosensitive recording layer, the protective layer, the intermediate Although it may be either a layer or a backcoat layer, the resin having a reactive carbonyl group in the side chain and the polyfunctional semicarbazide compound must be present in the same layer or in adjacent layers. In the present invention, the following state is preferable. The heat-sensitive recording layer contains a resin having a reactive carbonyl group and a polyfunctional semicarbazide compound. A resin having a reactive carbonyl group and a polyfunctional semicarbazide compound are contained in the protective layer. A resin having a reactive carbonyl group and a polyfunctional semicarbazide compound are contained in the backcoat layer. A resin having a reactive carbonyl group in the protective layer and a polyfunctional semicarbazide compound are contained in the thermosensitive recording layer. A resin having a reactive carbonyl group in the heat-sensitive recording layer and a polyfunctional semicarbazide compound are contained in the intermediate layer. In order to obtain a heat-sensitive recording material having excellent water resistance, it is particularly preferable to cause a crosslinking reaction at least in the outermost layer. In the case of a heat-sensitive recording material having a protective layer, the protective layer has a protective layer. In the case of a non-thermosensitive recording material, a state in which a resin having a reactive carbonyl group in the side chain and a polyfunctional semicarbazide compound undergo a crosslinking reaction in the thermosensitive recording layer is particularly preferable.

  The polyfunctional semicarbazide compound used in the present invention is a compound having two or more reactive semicarbazide groups in the molecule, and is represented by the following general formula 1.

  In the formula, n represents 2 or more, and R represents a linking group containing at least one carbon. The semicarbazide group represented by the general formula 1 generates a semicarbazone bond by a crosslinking reaction with a resin having a reactive carbonyl group in the side chain because the terminal amino group has high reactivity with the reactive carbonyl group. High water resistance can be obtained. This semicarbazone bond is superior to the hydrazone bond produced by the reaction of the hydrazide group of carboxylic acid dihydrazide, etc. with the carbonyl group, because it is delocalized in a wide range, and it is difficult to cause a decomposition reaction and is highly stable. Water resistance is obtained. In the present invention, a trifunctional semicarbazide compound is preferably used from the viewpoint of reactivity with a carbonyl group and water resistance obtained by the reaction. Furthermore, since the polyfunctional semicarbazide compound is a burette litri (hexamethylene semicarbazide) represented by the following chemical formula, more excellent water resistance strength can be stably realized. A specific example of burette litri (hexamethylene semicarbazide) is Hardener SC manufactured by Asahi Kasei Chemicals.

  In the present invention, the content of the polyfunctional semicarbazide compound is not particularly limited in the range of its effects, but when it is contained in the same layer as the resin having a reactive carbonyl group in the side chain, the reactive carbonyl group is included in the side chain. Is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, based on the resin contained in

  The resin having a reactive carbonyl group in the side chain used in the present invention is a resin in which a reactive carbonyl group such as diacetone group or acetoacetyl group is introduced into the side chain of the resin by any method. The following systems are listed. Starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polyacrylic acid soda, polyethylene terephthalate, Polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide, polymethylpentene, polyphenylene oxide , Polyphenylene sulfide, polyphenylene sulfone, polysulfone, poly Relate, polyallylsulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenolic resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin, bismaleimide triazine resin , Alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylamide / Acrylate ester copolymer, acrylate amide / acrylate ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, ethylene / anhydrous Alkali salts or ammonium salts of ynoic acid copolymer, there are other various polyolefin resins, among others, polyvinyl alcohol is preferably used to provide a high surface strength by excellent bonding strength. By using diacetone-modified polyvinyl alcohol in which a diacetone group is introduced as a reactive carbonyl group in the side chain of polyvinyl alcohol, particularly excellent water resistance strength can be realized.

  Diacetone-modified polyvinyl alcohol is a partially or completely saponified product of a copolymer of a monomer having a diacetone group and vinyl acetate, and a resin obtained by copolymerizing a monomer having a diacetone group and vinyl acetate. It is produced by saponifying. The content of the monomer having a diacetone group in diacetone-modified polyvinyl alcohol is not particularly limited, but is preferably in the range of 0.5 to 15 mol% with respect to all monomers in diacetone-modified polyvinyl alcohol. 1-10 mol% is especially preferable. The polymerization degree of diacetone-modified polyvinyl alcohol is preferably in the range of 300 to 4000, particularly preferably 1000 to 2000. The degree of saponification is preferably 90% or more, particularly preferably 95 to 98%.

  In the present invention, when the resin having a reactive carbonyl group in the side chain and the polyfunctional semicarbazide compound are contained in one of the protective layer and the heat-sensitive recording layer, the layer containing both the reactive carbonyl group By coating and drying on a support in the state of an aqueous coating solution containing a resin having a side chain, a polyfunctional semicarbazide compound and ammonia, a coating having excellent production stability and high water resistance It becomes possible to obtain a layer. The reaction of the reactive carbonyl group and the semicarbazide group is promoted in an acidic state, but the reaction is suppressed in the state of the coating liquid by containing ammonia in the coating liquid and kept on the alkali side. As the ammonia volatilizes and the pH shifts in the acid direction, the reaction proceeds and water resistance is achieved.

  In the present invention, in addition to the resin having a reactive carbonyl group in the side chain and the polyfunctional semicarbazide compound, a known resin and / or a crosslinking agent can be used in combination as long as the effects of the present invention are not impaired.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can be obtained by mixing each aqueous dispersion obtained by finely pulverizing each color forming component and a resin, and coating and drying on a support.

  The electron donating compound, which is a normally colorless or light dye precursor contained in the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention, is generally used for pressure-sensitive recording materials and heat-sensitive recording materials. Although it is represented, it is not particularly limited.

As an example of a specific dye precursor,
(1) Triarylmethane compounds: 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (P-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (P-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3 -Bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl)- -Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl)- 6-dimethylaminophthalide, etc.

  (2) Diphenylmethane compounds: 4,4′-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenylleucooramine, N-2,4,5-trichlorophenylleucooramine, etc.

  (3) Xanthene compounds: Rhodamine B anilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino- 7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-6-methyl-7- (3-methylphenylamino) fluorane, 3 -Diethylamino-7- (3,4-dichloroanilino) fluorane, 3-dibutylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl -7-anilinofluorane, 3-dibutyla No-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilino Fluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4- Nitroanilino) fluorane, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluor Oran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7- Nirinofuruoran, 3-diethylamino-6-methyl-7- (3-trifluoromethyl) -6-fluoran and the like,

  (4) Thiazine compounds: benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc.

  (5) Spiro compounds: 3-methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3'-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphtholopyrans (3-methoxy) Benzo) spiropyran, 3-propyl spirobenzopyran and the like. These dye precursors can be used alone or in admixture of two or more as required.

  The electron-accepting compound that is a developer contained in the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention is generally represented by a pressure-sensitive recording material or an acidic substance used in the heat-sensitive recording material. It is not particularly limited. For example, phenol derivatives, aromatic carboxylic acid derivatives, N, N′-diarylthiourea derivatives, arylsulfonylurea derivatives, polyvalent metal salts such as zinc salts of organic compounds, benzenesulfonamide derivatives, urea urethane compounds, etc. Can do.

  Specific examples of the electron-accepting compound contained in the heat-sensitive recording layer are listed below, but are not necessarily limited to these compounds.

  4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxydiphenylsulfone, 4 -Hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy-4'-n-butoxydiphenylsulfone, 4-hydroxy-4 '-Benzyloxydiphenylsulfone, bis (4-hydroxyphenyl) sulfone monoallyl ether, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (3,5-dibromo-4-hydroxyphenyl) sulfone, bis (3 , -Dichloro-4-hydroxyphenyl) sulfone, 3,4-dihydroxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, 3,4,4'-trihydroxydiphenylsulfone, 4,4 '-[oxybis (Ethyleneoxy-p-phenylenesulfonyl)] diphenol, 3,4,3 ′, 4′-tetrahydroxydiphenylsulfone, 2,3,4-trihydroxydiphenylsulfone, 3-phenylsulfonyl-4-hydroxydiphenylsulfone, 2,4-bis (phenylsulfonyl) phenol,

  4-phenylphenol, 4-hydroxyacetophenone, 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, , 1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl)- 2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,3-bis [1- (4- Hydroxyphenyl) -1-methylethyl] benzene, 1,3-bis [1- (3,4-dihydroxyphenyl) -1-methyl ester L] benzene, 1,4-bis [1- (4-hydroxyphenyl) -1-methylethyl] benzene, 4,4'-dihydroxydiphenyl ether, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, Bis (2-hydroxynaphthyl) methane,

  2,2-bis (4-hydroxyphenyl) methyl acetate, 2,2-bis (4-hydroxyphenyl) butyl acetate, 4,4-thiobis (2-tert-butyl-5-methylphenol), 4-hydroxyphthal Dimethyl acid, benzyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, benzyl gallate, stearyl gallate, pentaerythritol tetra (4-hydroxybenzoic acid) ester, pentaerythritol tri (4-hydroxybenzoic acid) ester, N Dehydration condensate of 4-butyl-4- [3- (p-toluenesulfonyl) ureido] benzoate, 2,2-bis (hydroxymethyl) -1,3-propanediol polycondensate and 4-hydroxybenzoic acid,

  N, N'-diphenylthiourea, 4,4'-bis [3- (4-methylphenylsulfonyl) ureido] diphenylmethane, N- (4-methylphenylsulfonyl) -N'-phenylurea, N- (benzenesulfonyl) ) -N '-[3- (4-toluenesulfonyloxy) phenyl] urea, N- (4-toluenesulfonyl) -N'-[3- (4-toluenesulfonyloxy) phenyl] urea, urea urethane compound,

  Salicylanilide, 5-chlorosalicylanilide, salicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-bis (α-methylbenzyl) salicylic acid, 4- [2 ′-(4-methoxyphenoxy) ethyloxy] salicylic acid , 3- (octyloxycarbonylamino) salicylic acid or metal salts (for example, zinc salts) of these salicylic acid derivatives,

  N- (4-hydroxyphenyl) -4-toluenesulfonamide, N- (2-hydroxyphenyl) -4-toluenesulfonamide, N-phenyl-4-hydroxybenzenesulfonamide and the like.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can contain a heat-fusible substance as a sensitizer in order to improve its thermal response. In this case, those having a melting point of 60 to 180 ° C are preferable, and those having a melting point of 80 to 140 ° C are more preferably used.

  Specifically, stearic acid amide, N-hydroxymethyl stearic acid amide, N-stearyl stearic acid amide, ethylene bis stearic acid amide, methylene bis stearic acid amide, methylol stearic acid amide, N-stearyl urea, benzyl-2- Naphthyl ether, m-terphenyl, 4-benzylbiphenyl, 2,2′-bis (4-methoxyphenoxy) diethyl ether, α, α′-diphenoxy-o-xylene, bis (4-methoxyphenyl) ether, adipic acid Diphenyl, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4-chlorobenzyl) oxalate, dimethyl terephthalate, dibenzyl terephthalate, phenyl benzenesulfonate, bis (4-allyloxypheny And known heat-fusible substances such as sulfone, 1,2-bis (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 4-acetylacetophenone, acetoacetanilide, fatty acid anilide, and the like. However, when a higher fatty acid amide is used, it is more preferable because it functions as a lubricant.

  These compounds can be used alone or in combination of two or more. In order to obtain sufficient thermal responsiveness, it is preferable that the sensitizer occupies 5 to 50% by mass in the total solid content of the thermosensitive recording layer.

  In the present invention, diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide as a pigment in any layer Inorganic pigments such as barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, melamine resin, urea-formalin resin, polyethylene, nylon, styrene plastic pigment, acrylic plastic pigment, hydrocarbon Organic pigments such as plastic pigments can be used with the adhesive. Of these, kaolin is particularly preferable as the pigment for the protective layer, and exhibits excellent barrier properties and sticking properties. Also, as the intermediate layer pigment, calcined kaolin and / or organic hollow pigment is preferable, and a heat-sensitive recording material having excellent thermal response due to high heat insulation can be obtained. In particular, when an organic hollow pigment is used, excellent water resistance can be obtained.

  Moreover, arbitrary resin is used as an adhesive agent. Specific examples include starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polyacrylic acid. Soda, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide, poly Methyl pentene, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfone, poly Sulfone, polyarylate, polyallylsulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenol resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin, bis Maleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylic Acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, Alkali salts or ammonium salts of styrene / maleic anhydride copolymer, and other various polyolefin resins.

  Furthermore, in the protective layer and / or the heat-sensitive recording layer, for the purpose of improving the sticking property, for the purpose of improving the light resistance, the lubricant such as higher fatty acid metal salt, higher fatty acid amide, paraffin, polyolefin, polyethylene oxide, caster wax, etc., benzophenone Surfactants including anionic and nonionic high molecular weights, UV dyes such as benzotriazoles and benzotriazoles, and dispersing / wetting agents, as well as fluorescent dyes and antifoaming agents, are added as necessary. .

  As the support according to the present invention, neutral paper or acidic paper is mainly used, but in addition to paper, various woven fabrics, nonwoven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal foils, vapor deposition sheets, Or the composite sheet which combined these by bonding etc. can be arbitrarily used according to the objective.

The method for forming the heat-sensitive recording layer, the protective layer, the intermediate layer, and the backcoat layer is not particularly limited, and can be formed according to a conventionally known technique. Specific examples of coatings are film press coating, air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, and E-bar coating. Each layer can be formed by drying. In addition, each layer may be formed by various printing machines using a system such as a lithographic plate, a relief plate, a flexo, a gravure, a screen, and a hot melt. The coating amount of the thermosensitive recording layer is usually preferably 0.05 to 2.0 g / m ^{2 in} terms of the absolutely dry coating amount of the dye precursor in order to obtain sufficient thermal response. 0 g / m ² is more preferable. Ze'inuinurikoryou protective layer is preferably ^{0.2~10g / m 2, 1~5g / m} 2 is more preferable. Ze'inuinurikoryou of the intermediate layer is preferably ^{1~30g / m 2, 3~20g / m} 2 is more preferable.

  If necessary, the image quality can be improved by supercalendering after intermediate layer coating, heat-sensitive recording layer coating, protective layer coating, or after backcoat layer coating.

  Next, the present invention will be described in more detail with reference to examples. However, it is not limited to these. The parts and% shown below are based on mass, and the coating amount is the absolute dry coating amount.

Example 1
(1) Preparation of coating solution for intermediate layer 50 parts of calcined kaolin [manufactured by BASF: Ancilex], organic hollow particle dispersion liquid having a solid concentration of 27.5% [manufactured by Rohm & Haas: AF1055], 50% styrene A composition comprising 40 parts of a butadiene latex and 50 parts of a 10% aqueous oxidized starch solution and 100 parts of water was mixed and stirred to prepare an intermediate layer coating solution.

(2) Preparation of thermal recording layer coating liquid The following (A), (B), and (C) mixed liquids were each pulverized with a dynomill (WEB sand mill) so that the volume average particle diameter was 2 μm or less. Each dispersion was obtained.
(A) Dye precursor dispersion 3-dibutylamino-6-methyl-7-anilinofluorane 30 parts Sulfone-modified polyvinyl alcohol 2.5% aqueous solution 70 parts (B) Electron-accepting compound dispersion 4-hydroxy-4 '-Isopropoxydiphenylsulfone 30 parts Sulfone-modified polyvinyl alcohol 2.5% aqueous solution 70 parts (C) Pigment / sensitizer dispersion Aluminum hydroxide [manufactured by Showa Denko: Heidilite H42] 50 parts Benzyl-2-naphthyl ether 30 200 parts of a 2.5% aqueous solution of sulfone-modified polyvinyl alcohol

Next, in addition to the dispersions (A), (B), and (C), the following were mixed and stirred to prepare a thermal recording layer coating solution.
(A) Dye precursor dispersion 100 parts (B) Electron acceptor compound dispersion 100 parts (C) Pigment / sensitizer dispersion 280 parts Zinc stearate 40% aqueous dispersion [manufactured by Chukyo Yushi Co., Ltd .: SZ40] 25 parts Methylol stearamide 40% aqueous dispersion 25 parts Paraffin wax 20% aqueous dispersion 25 parts Completely saponified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry: NM-11] 10% aqueous solution
200 parts Water 100 parts

(3) Preparation of protective layer coating liquid The following composition was mixed and stirred for 2 hours to prepare a protective layer coating liquid.
Diacetone-modified polyvinyl alcohol [Nippon Vinegar-Poval: DM-17] 10% aqueous solution 50 parts Kaolin [Huber: HG90] 20% aqueous dispersion 10 parts Zinc stearate 30% aqueous dispersion 6 parts Multifunctional semicarbazide [Asahi Kasei Chemicals: Hardener SC] 5% aqueous solution
10 parts Water 50 parts

(4) Preparation of heat-sensitive recording material A neutral high-quality paper having a basis weight of 64 g / m ² , the solid coating amount of the coating solution for the undercoat layer is 5 g / m ² , and the coating amount of the coating solution for the heat-sensitive recording layer is Each layer is coated and dried so that the coating amount of the dye precursor is 0.5 g / m ² and the coating amount of the coating solution for the protective layer is 3 g / m ^2. Produced.

Example 2
In the preparation of the coating liquid for protective layer (3) of Example 1, instead of 50 parts of 10% aqueous solution of diacetone-modified polyvinyl alcohol [manufactured by Nippon Acetate / Poval: DM-17] [Nippon Synthetic Chemical Co., Ltd. Industrial-made: Z-200] A thermosensitive recording material was prepared in the same manner as in Example 1 except that 50 parts of a 10% aqueous solution was used.

Example 3
In the preparation of the coating solution for the thermosensitive recording layer of Example 1 (2), instead of 200 parts of a 10% aqueous solution of completely saponified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry: NM-11], diacetone-modified polyvinyl alcohol [ A thermosensitive recording material was prepared in the same manner as in Example 1 except that 180 parts of 10% aqueous solution manufactured by Poval: DM-17] and 20 parts of 10% aqueous solution of polyfunctional semicarbazide [manufactured by Asahi Kasei Chemicals: Hardener SC] were used.

Example 4
In the preparation of the coating solution for the thermosensitive recording layer of Example 1 (2), instead of 200 parts of a 10% aqueous solution of completely saponified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry: NM-11], diacetone-modified polyvinyl alcohol [ PVA: DM-17] 10% aqueous solution 180 parts and polyfunctional semicarbazide [Asahi Kasei Chemicals: Hardener SC] 20% aqueous solution 20 parts. (4) In the production of thermosensitive recording materials, the protective layer coating solution was heat sensitive. A thermosensitive recording material (without a protective layer) was produced in the same manner as in Example 1 except that the coating was not performed on the recording layer.

Comparative Example 1
In the preparation of the coating liquid for the protective layer in Example 1 (3), 10 parts of adipic acid dihydrazide 5% aqueous solution was used instead of 10 parts of 5% aqueous solution of polyfunctional semicarbazide (manufactured by Asahi Kasei Chemicals: Hardener SC), A thermosensitive recording material was produced in the same manner as in Example 1.

Comparative Example 2
In preparation of the coating solution for protective layer (3) of Example 1, 10 parts of 1,1,4-trimethylsemicarbazide 5% aqueous solution was used instead of 10 parts of 5% aqueous solution of polyfunctional semicarbazide (manufactured by Asahi Kasei Chemicals: Hardener SC). A thermosensitive recording material was produced in the same manner as in Example 1 except that it was used.

Comparative Example 3
In the preparation of the coating solution for protective layer (3) of Example 1, instead of 50 parts of 10% aqueous solution of diacetone-modified polyvinyl alcohol (Nippon Acetate / Poval: DM-17), completely saponified polyvinyl alcohol [Nippon Synthetic Chemical Industry Manufactured: NM-11] A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 50 parts of a 10% aqueous solution was used.

Comparative Example 4
In the preparation of the coating solution for the thermosensitive recording layer of Example 1 (2), instead of 200 parts of a 10% aqueous solution of completely saponified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry: NM-11], diacetone-modified polyvinyl alcohol [ Made by Poval: DM-17] 180 parts of a 10% aqueous solution and 20 parts of a 10% aqueous solution of adipic acid dihydrazide. (4) In the production of a thermosensitive recording material, the protective layer coating solution was not coated on the thermosensitive recording layer. A thermosensitive recording material (without a protective layer) was prepared in the same manner as in Example 1 except that.

  The thermosensitive recording materials produced in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to the following evaluation. The results are shown in Table 1.

[Water resistance 1]
For each of the produced heat-sensitive recording materials, two sheets were cut into a size of 5 cm × 5 cm, and the surface of the heat-sensitive recording material (Examples 1 to 3 and Comparative Examples 1 to 3 were protective layer surfaces, Example 4 and Comparative Example 4 were heat sensitive). A drop of water is dropped on the recording layer surface), the same heat-sensitive recording material is placed on top of each other so that the surfaces are in contact with each other, and a load of 2 kg is applied under an environment of 40 ° C./90% RH. Let stand for hours. Thereafter, the heat-sensitive recording materials were peeled from each other, and the water resistance strength was evaluated from the degree of adhesion between the surfaces. The evaluation criteria followed the following indicators.
(Double-circle): The adhesion between surfaces is not seen at all, but it can peel easily.
○: The surfaces are partly adhered but can be peeled off.
(Triangle | delta): The surfaces mutually adhere, it is hard to peel and a part coating layer peels off.
X: The surfaces are adhered to each other and cannot be peeled off or most of the coating layer is peeled off at the time of peeling.

[Water resistance 2]
For each of the produced thermal recording materials, one drop of water was dropped on the surface of the thermal recording material (Examples 1 to 3 and Comparative Examples 1 to 3 were protective layer surfaces, and Example 4 and Comparative Example 4 were thermal recording layer surfaces). Then, it was immediately rubbed with a finger 10 times, and the water resistance strength was evaluated by touch and visual observation of the finger on the surface. The evaluation criteria followed the following indicators.
A: There is no sliminess, and there is no peeling of the surface.
○: Although there is sliminess, there is no peeling of the surface.
Δ: There is sliminess, and the surface is peeled off a little.
X: The surface peels completely, and the finger reaches the paper as a support.

  As can be seen from Table 1, Examples 1-3 are superior in water resistance strength compared to Comparative Examples 1-3. Moreover, Example 4 which does not provide the protective layer is also excellent in water-proof water strength compared with Comparative Example 4 which similarly does not provide the protective layer. Comparative Examples 1, 2, and 4 contain a resin having a reactive carbonyl group in the side chain, but do not contain a polyfunctional semicarbazide compound. Comparative Example 3 contains a polyfunctional semicarbazide compound, but does not contain a resin having a reactive carbonyl group in the side chain.

Claims (5)

  A heat-sensitive recording material comprising a heat-sensitive recording layer that develops color by heat on a support, comprising a resin having a reactive carbonyl group in the side chain and a polyfunctional semicarbazide compound.   The heat-sensitive recording material according to claim 1, wherein the polyfunctional semicarbazide compound is contained in the heat-sensitive recording layer.   The heat-sensitive recording material according to claim 1 or 2, wherein the heat-sensitive recording material has a protective layer, and the polyfunctional semicarbazide compound is contained in the protective layer.   The heat-sensitive recording material according to claim 1, wherein the resin having a reactive carbonyl group in the side chain is diacetone-modified polyvinyl alcohol.   The heat-sensitive recording material according to any one of claims 1 to 4, wherein the polyfunctional semicarbazide compound is burette litri (hexamethylene semicarbazide).