JP4512571B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material, and relates to a heat-sensitive recording material having excellent image storability.

  The heat-sensitive recording material generally comprises a heat-sensitive recording layer mainly comprising an electron-donating usually colorless or light-colored dye precursor and an electron-accepting color developer on a support, a thermal head, By heating with a thermal pen, laser light or the like, the dye precursor and the developer react instantaneously to obtain a recorded image (see, for example, Patent Documents 1 and 2). 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 recent years, in particular, thermal recordings such as receipts for gas, water, electricity bills, ATM usage statements for financial institutions, various receipts, etc., financial recording sheets, thermal recording labels or thermal recording tags for POS systems, etc. Materials are being used.

  As the uses and demands of thermosensitive recording materials expand in this way, in addition to high thermal responsiveness and color density, which are basic characteristics, recording image storability has been demanded.

  As means for obtaining high recorded image storability in response to such demands, those using a specific phenol resin compound as an electron accepting compound have been disclosed (for example, see Patent Document 3).

  However, those using these specific phenol resin compounds as electron-accepting compounds are excellent in water resistance (for example, residual ratio of image density after a certain period of time when the colored portion is immersed in tap water), but plasticizers The property (for example, the residual ratio of the image density after a predetermined time when a wrap film containing a plasticizer is brought into contact with the color developing portion) is hardly sufficient.

Similarly, a method of using a specific electron-accepting compound and a phenol resin compound in combination is disclosed (for example, see Patent Document 4), but the heat resistance is insufficient.
Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039 Japanese Patent No. 3733081 Japanese Patent Laid-Open No. 7-81221

  An object of the present invention is to solve these problems and to provide a heat-sensitive recording material excellent in image storability, particularly heat storability, plasticizer and water storability.

  As a result of intensive studies, the present inventors have invented the heat-sensitive recording material of the present invention that can solve the problems. That is, in a thermosensitive recording material provided with a thermosensitive recording layer containing an electron-accepting compound that reacts with an electron-donating usually colorless or light-colored dye precursor on heating on the support to develop a color of the dye precursor, A thermosensitive recording comprising a phenol resin (condensate of phenol and formalin) to which glycidyl acrylate or glycidyl methacrylate represented by the following general formula (1) is added as an electron-accepting compound in the thermosensitive recording layer. Material.

In the formula, R ₁ represents the general formula (2). R ₁ may be the same as or different from each other. m represents an integer of 0 or 1, and at least one of m represents 1. n represents an integer of 2 to 5.

In the formula, R ₂ represents a methyl group or a hydrogen atom.

  A heat-sensitive recording material comprising a support and a heat-sensitive recording material comprising an electron-accepting compound that reacts with an electron-donating usually colorless or light-colored dye precursor upon heating to develop a color of the dye precursor. By using the phenol resin represented by the general formula (1) as the electron-accepting compound in the recording layer, image storability, particularly heat storability, plasticizer resistance and water storability can be greatly improved. it can.

  Hereinafter, the content of the present invention will be described more specifically. The heat-sensitive recording material of the present invention has a heat-sensitive recording layer containing, on a support, an electron-donating compound that is an electron-donating usually colorless to light-colored dye precursor and an electron-accepting compound that reacts when heated to develop a color of the dye precursor. It is.

  As the support used in the present invention, paper is mainly used, but in addition to paper, various woven fabrics, non-woven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal stays, vapor deposition sheets, or bonding them together The composite sheet combined in (1) can be arbitrarily used depending on the purpose.

As the phenol resin according to the heat-sensitive recording material of the present invention, a compound represented by the general formula (1) obtained by adding glycidyl methacrylate or glycidyl acrylate to phenol is used. In the formula, m may be 0 or 1, but at least one of m is 1. n is an integer of 2 to 5. In the formula, R ² is a methyl group or hydrogen.

  The phenol resin represented by the general formula (1) is not particularly limited as long as it is within the above range, but preferably n is 2 to 4, and specific examples include the following. .

  Further, by using two or more phenol resins represented by the general formula (1) in combination, a heat-sensitive recording material having further excellent image storage stability can be obtained. Preferably, three or more types of phenol resins are used in combination, and each n is different from each other.

  The dye precursors used in the heat-sensitive recording material of the present invention are typically represented by pressure-sensitive recording materials or those used in heat-sensitive recording materials, but are not limited thereto.

A specific example is as follows.
(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, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 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- 6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- Anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino- 6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluor 3- (N-ethyl-N-tolyl) amino-6-methyl-7-phenethylaminofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluorane, 3-diethylamino- 7-phenoxyfluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilino Fluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, etc.

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

  (5) Spiro compounds: 3-methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthyl- (3-methoxybenzo ) Spiropyran, 3-propyl spirobenzopyran and the like can be mentioned, but are not limited thereto, and can be used alone or in admixture of two or more as required.

  The mass ratio of the phenol resin represented by the general formula (1) of the present invention and the electron-donating dye precursor is preferably in the range of 0.05: 1 to 10: 1. More preferably, it is the range of 0.1: 1-5: 1.

  In addition to the phenol resin represented by the general formula (1), the heat-sensitive recording material of the present invention can be used in combination with one or more other electron-accepting compounds. The electron-accepting compound that can be used in combination is typically represented by an electron-accepting compound used for a pressure-sensitive recording material or a heat-sensitive recording material, but is not limited thereto. Examples thereof include phenol derivatives, aromatic carboxylic acid derivatives, N, N′-diarylthiourea derivatives, arylsulfonylurea derivatives, polyvalent metal salts such as zinc salts of organic compounds, and benzenesulfonamide derivatives.

  Specific examples include clay clay such as acid clay, activated clay, zeolite, bentonite and kaolin, p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4. '-N-propoxydiphenylsulfone, 3-phenylsulfonyl-4-hydroxydiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclododecane, 2, 2-bis (4-hydroxyphenyl) Propane, 2,2-bis (4-hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) octane, 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 [2- (4-hydroxyphenyl) -2-propyl] benzene, 1,3-bis [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-bis [2- (4-hydroxyphenyl) -2-propyl] benzene, 4,4′-dihydroxy Diphenyl ether, N- (2-hydroxyphenyl) benzenesulfonamide, N- (2-hydroxyphenyl) -p-toluenesulfonamide, N- ( -Hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -p-toluenesulfonamide, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4, 4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-allyloxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, Np- Toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea, 3,3′-dichloro-4,4′-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, 2, 2-bis (4-hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-tert-butyl-5-methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, N -(4-hydroxyphenylsulfonyl) aniline, bis [4- (4-toluenesulfonyl) aminocarbonylaminophenyl] methane, salicylanilide, 5-chlorosalicylanilide, novolak phenol resin, modified terpene phenol resin, 3,5-di -Tert-butylsalicylic acid, 3,5-di-tert-nonylsalicylic acid, 3,5-didodecylsalicylic acid, 3-methyl-5-tert-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-bis (α, α -Dimethylbenzyl) salicylic acid , 3-methyl-5- (α-methylbenzyl) salicylic acid, 4-n-octyloxycarbonylaminosalicylic acid, and the like, and metal salts such as zinc, nickel, aluminum, calcium, and the like. It is not limited and it can also be used in combination of 2 or more types as needed.

  The heat-sensitive recording material of the present invention can provide practically sufficient image storage stability, but if necessary, a hindered phenol compound, a hindered amine compound, a phosphate ester derivative, or a benzotriazole derivative may be added. Can do.

  Specific examples of hindered phenol compounds used in the heat-sensitive recording layer in the present invention as needed include 1,1,2,2-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) ethane. 1,1,2,2-tetrakis (3-phenyl-4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-tert-butyl-4-hydroxyphenyl) ethane, 1,1,3 -Tris (3-cyclohexyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-cyclohexyl-4-hydroxy-2-methylphenyl) butane, 1,1,3-tris (3-cyclohexyl-4 -Hydroxy-5-methylphenyl) butane, 1,1,3-tris (3-phenyl-4-hydroxyphenyl) butane, 1,1,3-to (5-phenyl-4-hydroxy-2-methylphenyl) butane, 1,1,3-tris (3-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-tert- Butyl-4-hydroxy-2-methylphenyl) butane, 1,1,3,3-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3- Cyclohexyl-4-hydroxyphenyl) propane, 1,1,5,5-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) pentane, 1,1,3,3-tetrakis (3-cyclohexyl-4-) Hydroxyphenyl) pentane, 1,1,3,3-tetrakis (3-phenyl-4-hydroxyphenyl) propane, 1,1,3,3 Tetrakis (5-phenyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3-tert-butyl-4-hydroxyphenyl) propane, 1,1,3,3-tetrakis ( 5-tert-butyl-4-hydroxy-2-methylphenyl) propane, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-) tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4, 4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2,6-di-) Methylphenol), 4,4'-thiobis (2,6-di-tert-butylphenol), 2,2'-thiobis (4-tert-octylphenol), 2,2'-thiobis (3 -Tert-octylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] 4- [ α ′, α′-bis (4-hydroxyphenyl) ethyl] benzene, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5- Examples thereof include, but are not limited to, dimethylphenyl) propane, and these compounds can be used alone or in combination of two or more as required.

  Specific examples of the hindered amine compound used in the heat-sensitive recording layer in the present invention as needed include bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate and succinic acid-bis (2 , 2,6,6, -tetramethyl-4-piperidyl) ester, butane-1,2,3,4-tetracarboxylic acid-tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) ester , Butane-1,2,3,4-tetracarboxylic acid-tetrakis (2,2,6,6-tetramethyl-4-piperidyl) ester and the like, but is not limited thereto, These compounds can be used alone or in combination of two or more as required.

  Specific examples of the phosphate ester derivative used as necessary for the heat-sensitive recording layer in the present invention include triphenyl phosphate, diphenyl phosphate, bis (4-tert-butylphenyl) phosphate, bis (4,6-di-). -Tert-butylphenyl) phosphate, bis (4-chlorophenyl) phosphate, bis (benzyloxyphenyl) phosphate, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, dimethyloxyphosphate, diethyloxy Phosphate, bis (3,5-di-tert-butyl-4-hydroxyphenyl) phosphate, 3,5-di-tert-butyldiphenyl phosphate, diethyl (3,5-di-tert-butyl-4-hydroxyphenyl) Phosphate And 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate sodium salt, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate calcium salt, 2,2 Mention of zinc salt of '-methylenebis (4,6-di-tert-butylphenyl) phosphate, ammonium salt of 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, potassium salt, etc. However, it is not limited to this, and these compounds can be used alone or in combination of two or more as required.

  Specific examples of the benzotriazole derivatives used as necessary for the heat-sensitive recording layer in the present invention include 2- (2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3-tert-butyl) -5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di -Tert-aminophenyl) benzotriazole, 2- (2-hydroxy-3,5-di-ter -Butylphenyl) -5-tert-butylbenzotriazole, 2- (2-hydroxy-3-dodecyl-5-methylphenyl) benzotriazole, 2- [2-hydroxy-4- (2-ethylhexyl) oxyphenyl] benzo Triazole, condensate with methyl-3- (3-tert-butyl-5-benzotriazolyl-4-hydroxyphenyl) propionate-polyethylene glycol (molecular weight about 300), 5-tert-butyl-3- (5- Chloro-benzotriazolyl) -4-hydroxybenzene-octylpropionate, 2- (2-hydroxy-3-sec-butyl-5-tert-butylphenyl) -5-tert-butylbenzotriazole, 2- (2 -Hydroxy-4-methoxy-5-sulfophenyl) benzotriazol Sodium salt, 2- (2-hydroxy-4-butoxy-5-sulfophenyl) benzotriazole sodium salt, 2,2'-methylenebis (4-methyl-6-benzotriazolylphenol), 2,2'-methylenebis [4-Methyl-6- (5-methylbenzotriazolyl) phenol], 2,2'-methylenebis [4-methyl-6- (5-chlorobenzotriazolyl) phenol], 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-benzotriazolylphenol], 2,2'-methylenebis (4-tert-butyl-6-benzotriazolylphenol), 2, 2'-propylidenebis (4-methyl-6-benzotriazolylphenol), 2,2'-isopropylidenebis (4-methyl-6-benzoto) Azolylphenol), 2,2'-isopropylidenebis [4- (1,1,3,3-tetramethylbutyl) -6-benzotriazolylphenol], 2,2'-octylidenebis [4-methyl- 6- (5-methylbenzotriazolyl) phenol] and the like, but is not limited thereto, and these compounds are used alone or in combination of two or more as required. can do.

  The amount of hindered phenol compound, hindered amine compound, phosphate ester derivative, or benzotriazole derivative used as necessary for the heat-sensitive recording layer in the present invention is a total amount of 5 to 5% of the dye precursor. 100 mass% is a preferable range, and a more preferable range is 10 to 80 mass%. In this range, the thermal responsiveness, the saturated density of the colored image is good, the whiteness of the background portion is good, and the high-temperature heat-resistant storage stability improving effect of the colored image portion and the non-colored background portion is high. The heat-resistant storage stability of the part is also improved.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can contain a heat-fusible substance in order to improve its thermal response. In this case, those having a melting point of 60 to 180 ° C. are preferred, 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, N-stearyl urea, 1,2-bisphenoxyethane, 1,2-bis (3 -Methylphenoxy) ethane, benzyl-2-naphthyl ether, m-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl 2,2'-bis (4-methoxyphenoxy) diethyl ether, α, α'-diphenoxyxylene 1,2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, Acid bis (4-chlorobenzyl) ester, dimethyl terephthalate And known thermofusible substances such as dibenzyl terephthalate, benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 4-acetylacetophenone, acetoacetic anilides and fatty acid anilides. These compounds can be used alone or in combination of two or more. Further, in order to obtain sufficient thermal responsiveness, it is preferable that the heat fusible substance occupies 5 to 50% by mass in the total solid content of the thermosensitive recording layer.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can be obtained by mixing each dispersion obtained by finely pulverizing each color forming component and a binder, and coating and drying on a support. The heat-sensitive recording layer may have a single layer structure or multiple layers.

  As the binder used in the heat-sensitive recording layer, various binders used in ordinary coating can be used.

  Specifically, starches, hydroxymethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic Acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, isobutylene / Water-soluble binder such as alkali salt of maleic anhydride copolymer, and styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene Copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylate copolymer, ethylene / vinyl acetate copolymer, polyacrylate, styrene / acrylate copolymer Examples thereof include water-dispersible binders such as coalescence and polyurethane, but are not limited thereto.

  For the heat-sensitive recording layer, diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate are used as pigments. Inorganic pigments such as zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, and nylon powder can be used.

  In addition, the heat-sensitive recording layer has a higher fatty acid metal salt such as zinc stearate and calcium stearate, a higher fatty acid amide such as stearic acid amide, paraffin, polyethylene wax, polyethylene oxide for the purpose of preventing thermal print head wear and sticking. Further, surfactants including anionic and nonionic high molecular weight materials, as well as fluorescent dyes, antifoaming agents, and the like are added as necessary as lubricants such as castor wax and dispersing / wetting agents.

  The method for forming the heat-sensitive recording layer is not particularly limited, and can be formed according to a conventionally known technique. Specific examples include various printing methods such as letterpress, lithographic, flexo, and gravure, air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, and E-bar coating. The heat-sensitive recording layer can be formed by coating the coating liquid on the support by a method such as coating and drying.

The solid coating amount of the heat-sensitive recording layer is usually 0.1 to 2.0 g / m ^{2 as} the solid coating amount of the dye precursor. By setting it within this range, the recorded image and thermal response are excellent, and the cost is advantageous.

In the heat-sensitive recording material of the present invention, if necessary, one or more undercoat layers containing a single layer or a plurality of layers of pigments or resins can be provided between the support and the heat-sensitive recording layer. When the heat-sensitive recording material of the present invention is provided with a subbing layer, the solid coating amount of the undercoat layer is preferably ^{1~30g / m 2, 3~20g / m} 2 is more preferable.

  In general, calcined kaolin is used as a pigment for the undercoat layer. In addition, diatomaceous earth, talc, kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, Inorganic pigments such as magnesium hydroxide, titanium dioxide, barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, melamine resin filler, urea-formalin resin filler, polyethylene powder, nylon powder, acrylic resin Organic solid and hollow pigments such as fillers and styrene acrylic resin fillers can be used.

  As the resin for the undercoat layer, various water-soluble resins or water-dispersible resins used in ordinary coating can be used. For example, starches, hydroxymethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylate ester copolymer, acrylamide / acrylate ester / Methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, isobutylene / maleic anhydride Water-soluble resin such as alkali salt of copolymer, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer , Acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, polyurethane, etc. And water dispersible resin.

In the heat-sensitive recording material of the present invention, a protective layer can be formed on the heat-sensitive recording layer in order to further improve the chemical resistance of the image or to improve the recording running property as necessary. Such a protective layer is mainly composed of a water-soluble resin having a film-forming property or a water-dispersible resin, and is added to the ultraviolet absorber and the heat-sensitive recording layer as necessary while the adhesive is dissolved or dispersed. auxiliaries protective layer coating solution prepared by adding such to obtain the heat-sensitive recording layer, the coating amount after drying 0.2 to 10 g / m ^2, more preferably 0.5 to 5 g / m ² approximately It is formed by coating and drying so that

  The water-soluble resin or water-dispersible resin for the protective layer is appropriately selected from conventionally known water-soluble polymers or water-dispersible resins. That is, examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, starch or derivatives thereof, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer. , Acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer An alkali salt of an isobutylene / maleic anhydride copolymer, sodium alginate, gelatin, casein, an acid neutralized product of chitosan, and the like can be used.

  Examples of water-dispersible resins include styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, methyl acrylate / butadiene copolymers, acrylonitrile / butadiene / styrene terpolymers, polyvinyl acetate, vinyl acetate / Acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, acrylonitrile / acrylic acid ester copolymer, acrylonitrile / acrylic acid ester / acrylic acid copolymer, Polyurethane or the like can be used.

  Among these, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol are preferably used as the protective layer resin because a strong film can be formed.

  The protective layer can contain a pigment for the purpose of improving the recording running property, writing property, and the like. Specific examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, sulfuric acid Inorganic pigments such as zinc, amorphous silica, amorphous calcium silicate, and colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, and nylon powder can be used.

  In addition, the protective layer has higher fatty acid metal salts such as zinc stearate and calcium stearate, higher fatty acid amides such as stearic acid amide, paraffin, polyethylene wax for the purpose of improving recording running properties such as heat print head wear prevention and sticking prevention. Further, lubricants such as polyethylene oxide and castor wax are added as necessary.

  The formation method of the undercoat layer and the protective layer is not particularly limited, and can be formed according to a conventionally known technique. Specific examples include various printing methods, air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, E-bar coating, and other methods. And can be formed by drying.

  In the thermosensitive recording material of the present invention, an optional information recording layer such as a protective layer (barrier), an adhesive layer, a magnetic recording layer, an ink jet recording layer, etc. Or a smoothing process such as super calendering can be applied after each layer is applied.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited to this. In addition, all the number of parts shown in an Example is a mass reference | standard.

  In the following manner, a heat-sensitive recording material used in Example 1 was produced and evaluated for characteristics.

<Preparation of dispersion A>
Disperse 15 parts by mass of the phenol resin represented by the following formula (1) and 15 parts by mass of the phenol resin represented by the following formula (2) in a mixture of 15 parts by mass of a 10% by mass sulfone-modified polyvinyl alcohol aqueous solution and 55 parts by mass of water. Dispersion A was obtained by pulverization with a bead mill until the average particle size became 0.8 μm.

<Preparation of dispersion B>
30 parts by mass of 3-dibutylamino-6-methyl-7-anilinofluorane is dispersed in a mixture of 15 parts by mass of a 10% by mass sulfone group-modified polyvinyl alcohol aqueous solution and 55 parts by mass of water, and the average particle size is 1 μm by a bead mill. Dispersion B was obtained by grinding until

<Preparation of dispersion C>
30 parts by mass of benzyl-2-naphthyl ether is dispersed in a mixture of 15 parts by mass of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 55 parts by mass of water, and is pulverized with a bead mill until the average particle size becomes 0.8 μm. C was obtained.

<Preparation of dispersion D>
30 parts by weight of light calcium carbonate was dispersed in 70 parts by weight of a 0.5% by weight aqueous solution of ammonium polycarboxylate, and stirred for 10 minutes with a homomixer to obtain dispersion D.

<Preparation of thermal recording layer coating solution>
100 parts by weight of the above dispersion A, 50 parts by weight of dispersion B, 100 parts by weight of dispersion C, 75 parts by weight of dispersion D, 15 parts by weight of 30% by weight zinc stearate dispersion, 180 parts by weight of a completely saponified aqueous polyvinyl alcohol solution Then, water was added so that the concentration of the thermal coating solution was 20% by mass, and the mixture was sufficiently stirred to prepare a thermal recording layer coating solution.

<Preparation of heat-sensitive coated paper>
A coating solution for forming an undercoat layer comprising 100 parts by weight of calcined kaolin, 24 parts by weight of 50% by weight styrene butadiene latex, and 200 parts by weight of water is 10 g / m as a solid coating amount on a fine paper having a basis weight of 50 g / m ^2. Coated and dried to ² to produce a heat-sensitive coated paper.

<Preparation of thermal recording material>
On the heat-sensitive coated paper, the thermal recording layer coating liquid is coated and dried so that the solid content coating amount is about 2.5 g / m ^2, and then the surface is smoothed by calendaring. Was adjusted to 300 seconds to 700 seconds to prepare a heat sensitive recording material.

<Preparation of dispersion E>
Disperse 30 parts by mass of 4-hydroxy-4'-isopropoxydiphenylsulfone in a mixture of 15 parts by mass of a 10% by mass sulfone-modified polyvinyl alcohol aqueous solution and 55 parts by mass of water until the average particle size becomes 0.8 μm using a bead mill. The dispersion E was obtained by grinding.

  A thermosensitive recording material was produced in the same manner as in Example 1 except that 100 parts by mass of dispersion A in Example 1 was 20 parts by mass, and 100 parts by mass of dispersion E was further added.

(Comparative Example 1)
A thermosensitive recording material was produced in the same manner as in Example 1 except that 100 parts by mass of dispersion A was replaced by 100 parts by mass of dispersion E in Example 1.

(Comparative Example 2)
200 parts by mass of 2,6-bis [(2-hydroxy-5-methylphenyl) methyl] -4-methylphenol was dispersed in a mixture of 200 parts by mass of a 10% by mass sulfone-modified polyvinyl alcohol aqueous solution and 400 parts by mass of water, Dispersion F was obtained by pulverization with a bead mill until the average particle size became 0.8 μm. A thermosensitive recording material was produced in the same manner as in Example 1 except that 100 parts by mass of dispersion A in Example 1 was replaced by 100 parts by mass of dispersion F.

[Characteristic evaluation]
The following printing test, heat resistance test, plasticizer resistance test, and water resistance test were carried out on the resulting thermal recording material. The evaluation results are shown in Table 1.

[Print test]
A HG-100 type thermal gradient tester manufactured by Toyo Seiki Co., Ltd., caused a color to develop by contacting a thermal stamp at 150 ° C. for 5 seconds, and the optical density of the printed part was measured with a Gretag Macbeth RD-19 reflection densitometer (black mode). It was measured. The optical density values are shown in Table 1.

[Heat resistance test]
The heat-sensitive recording material used in the evaluation of the printability test was placed in an environment of 60 ° C. for 24 hours, and then the optical density of the print portion was measured with a Gretag Macbeth RD-19 reflection densitometer (black mode). The value obtained by dividing the optical density by the optical density in the printing test is shown in Table 1 as the image remaining rate in the heat resistance test. The larger the value of the residual rate, the better the heat-resistant image storage stability.

[Plasticizer resistance test]
A high wrap DX-300 manufactured by Mitsui Chemicals, Inc. Fabro Co., Ltd. was closely attached to the heat sensitive recording material used in the evaluation of the printability test, and was placed at room temperature for 10 hours. Measured with a meter (black mode). A value obtained by dividing the optical density by the optical density in the printing test is shown in Table 1 as an image remaining rate in the plasticizer resistance test. The greater the residual ratio, the better the plasticizer image storage stability.

[Water resistance test]
The heat-sensitive recording material used in the evaluation of the printability test was immersed in pure water at 20 ° C. for 24 hours and sufficiently dried at room temperature, and then the optical density of the printed portion was measured by Gretag Macbeth RD-19 reflection densitometer (black mode). ). The value obtained by dividing the optical density by the optical density in the printing test is shown in Table 1 as the image remaining rate in the water resistance test. The larger the residual ratio, the better the water-resistant image storage stability.

Claims (1)

A heat-sensitive recording material comprising a support and a heat-sensitive recording layer comprising an electron-donating compound that is an electron-donating usually colorless or light-colored dye precursor and reacts when heated to develop a color of the dye precursor. A thermosensitive recording material comprising a phenol resin (condensate of phenol and formalin) to which glycidyl acrylate or glycidyl methacrylate represented by the following general formula (1) is added as an electron-accepting compound in the recording layer.

(In the formula, R ₁ represents the general formula (2). R ₁ may be the same as or different from each other. M represents 0 or an integer of 1, and at least one of m represents 1. n. Represents an integer of 2 to 5.)

(In the formula, R ₂ represents a methyl group or a hydrogen atom.)