JP5036494B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material. More specifically, the present invention relates to a heat-sensitive recording material provided with a protective layer having good barrier properties against chemicals such as solvents and ink adhesion.

  The heat-sensitive recording material generally comprises a support on which a heat-sensitive recording layer mainly comprising an electron-donating usually colorless or light-colored dye precursor and an electron-accepting developer is provided. By heating with a laser beam, etc., the dye precursor and the electron-accepting developer react instantaneously to obtain a color image, the recording device is simple and easy to maintain, no noise is generated, etc. Because of its advantages, it is used in a wide range of fields such as measurement recorders, facsimiles, printers, computer terminals, POS label machines, and ticket vending machines.

  Conventional heat-sensitive recording materials sometimes have problems such as fading or disappearance of the printing portion when chemicals such as water, oil, or plasticizer come into contact with the recording portion. Since the applications have been diversified and have been used for tickets such as tickets and tickets, the problem of loss of records has become unacceptable, and the quality required from the market has become stricter. The role of a protective layer having a barrier property against chemicals has become important in order not to cause problems such as disappearance and fading of chemicals.

  As the applications of such heat-sensitive recording materials are diversified, many applications are being printed. In recent years, there has been a strong demand from the market for a heat-sensitive recording material having a protective layer that has excellent solvent-resistant barrier properties that do not cause background fogging even with printing, and has good adhesion to printing ink.

Many heat-sensitive recording materials having a protective layer have been proposed. For example, there is a method for improving the barrier property against chemicals such as a solvent or a plasticizer in a protective layer in a heat-sensitive recording material (see, for example, Patent Document 1). There is a problem that a good coating film cannot be formed. Moreover, although there exists a method (for example, refer patent document 2) which improves barrier property, the barrier property with respect to an organic solvent is inadequate. In addition, there is a method for improving the barrier property (see, for example, Patent Document 3), but due to the inorganic particles having a larger particle size than colloidal silica, a partially dense protective layer is not formed, and an organic solvent is used. Spot coloration occurs, the barrier property against the organic solvent is insufficient, and the adhesion with the ink is also insufficient.
JP 2004-299380 A JP 56-146794 A JP 2007-112043 A

  An object of the present invention is to provide a heat-sensitive recording material provided with a protective layer having good barrier properties against chemicals such as solvents and good ink adhesion.

  The present invention provides a thermosensitive recording material comprising a thermosensitive coloring layer and a protective layer in this order, wherein the protective layer contains polyvinyl alcohol, colloidal silica, and polydiallyldimethylammonium chloride. More preferably, in the protective layer, the polydiallyldimethylammonium chloride has a molecular weight of 10,000 to 250,000, and the heat-sensitive heat-sensitive polydialyldimethylammonium chloride is 0.0003 to 15.0 parts by mass with respect to 100 parts by mass of colloidal silica. The above problem has been solved by the recording material.

  According to the above invention, it is possible to provide a heat-sensitive recording material having a protective layer having good barrier properties against chemicals such as solvents and good ink adhesion.

  The contents of the present invention will be specifically described below. The thermosensitive recording material of the present invention is a thermosensitive recording material in which a thermosensitive coloring layer and a protective layer are provided in this order on a support, and the protective layer contains polyvinyl alcohol, colloidal silica, and polydiallyldimethylammonium chloride. More preferably, in the protective layer, the polydiallyldimethylammonium chloride has a molecular weight of 10,000 to 250,000, and the polydiallyldimethylammonium chloride is 0.0003 per 100 parts by mass of colloidal silica. It is a thermosensitive recording material which is -15.0 mass parts. The thermosensitive coloring layer according to the present invention preferably contains at least an electron-donating usually colorless or light-colored dye precursor, and an electron-accepting compound that reacts when heated to color the dye precursor. If necessary, an adhesive, various pigments, an image preservative, and the like that have been conventionally known in the heat-sensitive recording material field may be contained within a range that does not impair the effects of the present invention.

  The present invention provides a thermosensitive recording material comprising a thermosensitive coloring layer and a protective layer in this order, wherein the protective layer contains polyvinyl alcohol, colloidal silica, and polydiallyldimethylammonium chloride. More preferably, the protective layer has a molecular weight of 10,000 to 250,000, and a heat-sensitive recording material containing 0.0003 to 15.0 parts by mass of polydiallyldimethylammonium chloride with respect to 100 parts by mass of colloidal silica. A heat-sensitive recording material having a protective layer having a good barrier property against chemicals can be obtained.

The colloidal silica used for the protective layer according to the present invention is represented by SiO ₂ .xH ₂ O, and the production method thereof is obtained by diluting an alkali metal silicate with pure water and then contacting a strong acid cation exchange resin to remove alkali. After adding acid to make it strongly acidic, ammonia or amine is added to a part of the oligosilicic acid solution obtained by removing impurities using an ultrafiltration membrane, and heated to prepare a heel sol. The remaining oligosilicic acid solution is gradually added dropwise to obtain a silica sol, and an alkali metal silicate aqueous solution treated in the same manner as above is brought into contact with an H-type strongly acidic cation exchange resin or an OH-type strongly basic anion exchange resin. Then, an aqueous alkali metal hydroxide solution is added thereto and heated to 60 to 150 ° C. to form a stable aqueous sol, water is further removed through an ultrafiltration membrane, and then an H-type strongly acidic cation is obtained. A method for producing a stable aqueous silica sol substantially free from polyvalent metal oxides other than silica by contacting ammonia with an exchange resin and an OH type strongly basic anion exchange resin, and finally adding high purity silicate A method for producing colloidal silica excellent in stability obtained by hydrolysis in the presence of quaternary ammonium hydroxide and a dispersant is known.

  Not only general colloidal silica in which spherical or nearly spherical primary particles are connected independently but also chain particles in which small silica particles are elongated and connected, and they have a three-dimensional network structure. In addition, non-spherical colloidal silica having a shape such as a pearl necklace-like particle in which a plurality of spherical primary particles are connected and has a shape similar to a pearl necklace can also be used. A coating film composed of these chain silica particles and pearl necklace-like silica particles is excellent in mechanical strength.

  The elongated chain particles are those that do not have extension in the three-dimensional direction but extend in the same plane. The elongated chain particles include those that are substantially straight, bent, those having branches, those having a ring, and the like. On the other hand, the particles having a three-dimensional network structure are those having a network structure in which these elongated chain particles are literally three-dimensionally entangled.

  Each of the pearl necklace-like particles and the chain-like particles has a branched and elongated shape in which the primary particles of silica are connected, but the difference between the two is in the proportion occupied by the spherical primary particles. Here, the pearl necklace-like particle is a two-dimensional image obtained by an electron microscope. A circular figure caused by spherical primary particles has a roundness of 70% or more, and the total area of inscribed circles of each circular figure is pearl. Necklace-shaped particles occupy 70% or more of the total projected area, and the inscribed circles of the circular figures do not overlap each other. Here, the roundness is represented by the ratio of the radius of the inscribed circle to the radius of the circumscribed circle of the target figure outline, and is 100% for a perfect circle.

  Colloidal silica is produced with a particle size of about several nm to 1 μm. The particle size of the colloidal silica added to the protective layer is not particularly limited, but a fine one is desirable. Colloidal silica used in the present invention is, for example, from Nissan Chemical Industries, Ltd. Snowtex ST-20, ST-30, ST-40, ST-C, ST-N, ST-20L, ST-O, ST-OL, ST-S, ST-XS, ST-XL, ST-YL, ST-ZL, ST-OZL, ST-AK, ST-AKL, ST-AKYL, etc. are commercially available, and ADEKA Corporation as Adelite Ludox-CL, Ludox-CL-P, Ludox-HS40, Ludox-TMA, etc. are commercially available from GRACE-Davison.

  The polydiallyldimethylammonium chloride according to the present invention preferably has a molecular weight of 10,000 to 250,000, particularly preferably in the range of 20,000 to 90,000. About the addition amount, the range of 0.0003-15.0 mass parts is preferable with respect to 100 mass parts of colloidal silica, and the range of 0.02-1.0 mass part is more preferable. Outside the above molecular weight range and addition range, good barrier properties may not be obtained, and the quality is insufficient. The reason for the addition of polydiallyldimethylammonium chloride is not clear, but it is considered that polydiallyldimethylammonium chloride is adsorbed on the surface of the colloidal silica, thereby further stabilizing the colloidal silica in the liquid. This makes it less susceptible to mechanical shearing forces and temperature changes, and improves the dispersion stability of colloidal silica in the liquid. Also, with respect to other chemicals that tend to agglomerate colloidal silica, the choice of use is expanded because the dispersion stability in the liquid is improved.

  Examples of the polyvinyl alcohol used in the protective layer according to the present invention include completely saponified or partially saponified polyvinyl alcohol (hereinafter, non-modified polyvinyl alcohol), polyvinyl alcohol modified with various functional groups (hereinafter, modified polyvinyl alcohol), specifically Specifically, acetoacetyl group modified polyvinyl alcohol, carboxyl group modified polyvinyl alcohol, sulfonic acid group modified polyvinyl alcohol, amino group modified polyvinyl alcohol, ammonium base modified polyvinyl alcohol, olefin modified polyvinyl alcohol, nitrile group modified polyvinyl alcohol, amide group modified polyvinyl. Examples include alcohol, pyrrolidone-modified polyvinyl alcohol, and modified polyvinyl alcohol containing a silicon atom. By using polyvinyl alcohol, particularly modified polyvinyl alcohol, it is possible to improve the friction resistance and lubricity with the thermal recording head, to eliminate adhesion and debris adhesion in the thermal recording head, etc., and to improve head matching.

  The polymerization degree of unmodified polyvinyl alcohol is 500 or more, and the saponification degree is preferably 88% or more. When the degree of polymerization is less than 500, the barrier property against a chemical such as an organic solvent as a protective layer is lowered. Moreover, it is preferable that the polymerization degree of modified polyvinyl alcohol is 1000 or more, and 1000-2500 are more preferable. If the degree of polymerization is less than 1000, adhesion of adhesive residue on a thermal recording head or the like will occur. Further, the saponification degree of the modified polyvinyl alcohol is required to be 88% or more, and when the saponification degree is less than 88%, the water resistance is deteriorated.

  Among the modified polyvinyl alcohols, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, amino group or ammonium base-modified polyvinyl alcohol, ethylene-modified polyvinyl alcohol, silicon-containing modified polyvinyl alcohol and the like are preferable.

  The acetoacetyl group-modified polyvinyl alcohol comprises a polyvinyl alcohol resin having an acetoacetate group in the molecule. This acetoacetyl group-modified polyvinyl alcohol is (1) a method of adding diketene to a polyvinyl alcohol resin, (2) It can be obtained by a method of transesterifying an acetoacetic ester with a polyvinyl alcohol resin. 0.1-20 mol% is preferable and, as for content of the acetoacetate ester group in acetoacetyl group modification polyvinyl alcohol, 0.5-10 mol% is more preferable.

  When using acetoacetyl group-modified polyvinyl alcohol, a water-soluble crosslinking agent that can be crosslinked by reacting with acetoacetate groups is used. Examples of such cross-linking agents include dialdehydes such as glyoxal and polyaldehyde, polyamines such as polyethyleneimine, epoxy-based polyamide resins, diglycidyls such as glycerin diglycidyl ether, dimethylol urea, ammonium persulfate, and second chloride. Known compounds such as metal salts such as iron and magnesium chloride, ammonium chloride, and boric acid can be used.

  When the acetoacetyl group-modified polyvinyl alcohol is used in combination with the above-described crosslinking agent, a protective layer having water resistance at a low temperature such as dryness is formed due to the reactivity of the acetoacetyl group-modified polyvinyl alcohol. However, when the acetoacetyl group-modified polyvinyl alcohol and the crosslinking agent are mixed, the viscosity rapidly increases and gelation occurs. Therefore, it is desirable to use acetoacetyl group-modified polyvinyl alcohol, the crosslinking agent, and polyvinyl alcohol in combination.

  As the carboxyl group-modified polyvinyl alcohol, a reaction product of polyvinyl alcohol and carboxylic acid such as fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride, itaconic anhydride, or the like Examples include those obtained by esterifying the reaction product, or those obtained by saponifying a polymer of vinyl acetate and a small amount of an ethylenically unsaturated carboxylic acid such as maleic acid, fumaric acid or itaconic acid. When polyamide epichlorohydrin is used in combination with this carboxyl group-modified polyvinyl alcohol, it is excellent in durability, water resistance and the like.

  Examples of the amino group or ammonium base-modified polyvinyl alcohol include modified polyvinyl alcohol having a primary amino group or primary ammonium base, modified starch, a cellulose derivative, or a graft polymer or block polymer thereof. Among these amino group- or ammonium base-modified polyvinyl alcohols, modified polyvinyl alcohols having a primary amino group or a primary ammonium base are preferred from the viewpoints of adhesion and water resistance.

  The ethylene-modified polyvinyl alcohol is preferably a saponified random copolymer having a vinyl ester unit. Of these, ethylene-modified polyvinyl alcohol, which is a random polymer of 80:20 to 99: 1 in the ratio of the vinyl alcohol monomer component of polyvinyl alcohol to the ethylene monomer, is particularly preferable. In the case of ethylene-modified polyvinyl alcohol, in order to have water solubility and sufficient water resistance, the ethylene modification rate is 20 mol% (that is, the ratio of vinyl alcohol monomer component to ethylene monomer is 80:20) to 1 mol% (99: 1 as a ratio of vinyl alcohol monomer component to ethylene monomer) is preferable, and more preferably, the ethylene modification rate is 5 to 10 mol%. In the case of ethylene unmodified polyvinyl alcohol, sufficient water resistance cannot be obtained, and if the ethylene modification rate exceeds 20 mol%, the solubility in water is undesirably lowered.

  These ethylene-modified polyvinyl alcohols may be further modified with other functional groups as long as the performance and coating solution stability are not adversely affected. Specific examples include a carboxyl group, a terminal alkyl group, an amino group, a sulfonic acid group, a terminal thiol group, a silanol group, and an amide group. In order to impart solubility of highly syndiophilic polyvinyl alcohol, carboxyl group-modified, amino group-modified sulfonic acid groups and the like are effective.

  As for the usage-amount of the crosslinking agent with respect to ethylene modified polyvinyl alcohol, it is desirable to mix | blend 3-50 mass parts of crosslinking agents with respect to 100 mass parts of ethylene modified polyvinyl alcohol. When the blending amount of the crosslinking agent is less than 3 parts by mass, the degree of crosslinking modification is low and water resistance is insufficient. On the other hand, when it exceeds 50 parts by mass, the coating solution stability decreases, which is not preferable.

  Further, as the modified polyvinyl alcohol, silicon-containing modified polyvinyl alcohol can also be used. The silicon-containing modified polyvinyl alcohol is not particularly limited as long as it contains a silicon atom in the molecule, but a silicon atom usually contained in the molecule is an alkoxyl group, an acyloxyl group, a hydroxyl group obtained by hydrolysis or the like, or Those having a reactive substituent such as an alkali metal base are desirable. Details of the method for producing a modified polyvinyl alcohol containing a silicon atom in the molecule are described in JP-A-58-193189, and other production methods include (a) polyvinyl alcohol or carboxyl group. Or a method of introducing a silicon atom by post-exchange using a silylating agent in a modified polyvinyl acetate containing a hydroxyl group, and (b) a copolymer of a vinyl ester and an olefinically unsaturated monomer containing a silicon atom in the molecule. There is a method of saponifying a polymer.

  As the silicon-containing modified polyvinyl alcohol used in the present invention, among the silicon-containing modified polyvinyl alcohols prepared by the above method, the olefinic unsaturation containing silicon atoms in the molecule prepared by the method (b). A saponified product of a copolymer of a monomer and vinyl acetate is preferable, and a saponified product of a copolymer of vinyltrimethoxysilane and / or vinyltributoxysilane and vinyl acetate is particularly preferable. The silicon content of the silicon-containing modified polyvinyl alcohol can be appropriately selected and used according to the state of use, but is usually 0.01 to 5 in terms of an olefinically unsaturated monomer unit containing a silicon atom. It is 10 mol%, preferably 0.1 to 2.5 mol%.

  In the protective layer according to the present invention, in addition to polyvinyl alcohol, other binder components may be used in combination as long as the effects of the present invention are not impaired. Methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolysate, isobutylene-maleic anhydride copolymer Examples include hydrolysates, polypolymer hydrolysates, isobutylene-maleic anhydride copolymer hydrolysates, and polyacrylamides. However, the combined use of these water-soluble polymer compounds may cause a decrease in barrier properties and water resistance, and attention must be paid to the amount and type of the combined use.

  Synthetic rubber latex or synthetic resin emulsion is generally used as a water-insoluble polymer as a binder component that can be used in combination. Styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, acetic acid A vinyl emulsion, an acrylic emulsion, etc. are mentioned.

  In the protective layer, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium dioctylsulfosuccinate are used for the purpose of improving the matching with a recording head such as a thermal head. Various auxiliary agents such as water-soluble polyvalent salts such as surfactants (dispersing agents, wetting agents), antifoaming agents, potash alum, aluminum acetate, and the like can be appropriately added.

The coating solution for the protective layer according to the present invention can be obtained by mixing colloidal silica, polydiallyldimethylammonium chloride, polyvinyl alcohol, and the like, and a crosslinking agent and a catalyst if necessary. Furthermore, you may add a mold release agent, surfactant, wax, water repellent, etc. as needed. In the case of the obtained protective layer coating solution, the protective layer can be obtained by applying and drying on the thermosensitive coloring layer using an apparatus such as a bar coater, an air knife coater, a blade coater, or a curtain coater. The protective layer may be applied at the same time as the heat-sensitive coloring layer, or after the heat-sensitive coloring layer is applied, the heat-sensitive coloring layer may be once dried and applied thereon. Coating amount after drying of the protective layer according to the present invention is 0.2 to 10 g / m ^2, more preferably about 0.5 to 5 g / m ^2. When the coating amount is large, the thermal sensitivity is remarkably lowered, and when the coating amount is too low, the barrier property cannot be maintained. After applying the protective layer, a calendar process may be applied as necessary. The protective layer according to the present invention may have a single layer structure or a laminated structure.

  For the thermosensitive coloring layer according to the present invention, a colorless or light-colored electron-donating dye precursor, an electron-accepting compound that reacts when heated to color the dye precursor, and an adhesive are used.

  In the present invention, various known dye precursors can be used for the thermosensitive coloring layer. Specific examples of such dye precursors include the following, but the present invention is not limited to these. It is not something.

  Specific examples of such dye precursors are red, yellow, blue, green, and black, but are not limited to these in the present invention.

  Examples of red coloring dyes include 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide and 3,3-bis (1-n-butyl-2-methylindol-3-yl). ) Tetrachlorophthalide, 3,3-bis (1-n-butylindol-3-yl) phthalide, 3,3-bis (1-n-pentyl-2-methylindol-3-yl) phthalide, 3, 3-bis (1-n-hexyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 3,3-bis ( 1,2-dimethylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-propyl-2-methylindole) -3-yl) phthalide, 3 3-bis (2-methylindol-3-yl) phthalide, rhodamine B-anilinolactam, rhodamine B- (o-chloroanilino) lactam, rhodamine B- (p-nitroanilino) lactam, 3-dimethylamino-6-methyl -7-chlorofluorane, 3-dimethylamino-7-methylfluorane, 3-dimethylamino-7-methoxyfluorane, 3-dimethylamino-7-chlorofluorane, 3-ethylamino-7-methylfluorane ,

  3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methylfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methyl-7-chloro-8-benzylfluorane, 3-diethylamino-6,7-dimethylfluorane, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-7-methylfluorane Oran, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-ethoxyfluorane, 3-diethylamino-7- (N-acetyl-N-methyl) aminofluorane 3-diethylamino-7-p-methylphenylfluorane, 3 Diethylamino-7,8-benzofluorane, 3-diethylaminobenzo [a] fluorane, 3-diethylaminobenzo [c] fluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-chlorofluorane 3- (N-ethyl-N-isoamyl) amino-7,8-benzofluorane, 3- (N-ethyl-N-isoamyl) amino-7-methylfluorane, 3- (N-ethyl-N- Isoamyl) amino-benzo [a] fluorane,

  3- (N-ethyl-Nn-octyl) amino-6-methyl-7-chlorofluorane, 3- (N-ethyl-Nn-octyl) amino-7-methylfluorane, 3- (N -Ethyl-Nn-octyl) amino-7-chlorofluorane, 3- (N-ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-N-4) -Methylphenyl) amino-7-methylfluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7,8-benzofluorane, 3- (N-ethyl-N-ethoxyethyl) amino- 7-chlorofluorane, 3- (N-ethyl-N-ethoxyethyl) amino-7,8-benzofluorane, 3-di-n-butylamino-6-methyl-7-chlorofluorane, 3-di -N-butylamino-6-methyl- -Bromofluorane, 3-di-n-butylamino-7-methylfluorane, 3-di-n-butylamino-7-chlorofluorane, 3-di-n-butylamino-7,8-benzofluor Olane, 3-diallylamino-7,8-benzofluorane, 3-diallylamino-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-pyrrolidylamino-7-methylfluorane, 3 -N-ethyl-N-isoamylamino-6-phenoxyfluorane, 3-N-ethyl-N-isoamylamino-6-phenylfluorane, 3-N, N-dipentylamino-6-phenylfluorane, 3- N, N-diethyl-6-phenoxyfluorane, 3-N, N-dibutyl-6-phenoxyfluorane, 3-N, N-dipentyl-6-phenoxyv Red coloring dye such as Oran.

  Examples of yellow coloring dyes include 3,6-dimethoxyfluorane, 3-cyclohexylamino-6-chlorofluorane, 2,6-diphenyl-4- (4-dimethylaminophenyl) -pyridine, 2,2-bis ( 4- (2- (4-diethylaminophenyl) quinazolyl) oxyphenyl) propane, 4-chloro-N- (4- (N- (4-methylbenzyl) -N-methyl) aminobenzylidene) aniline, 1- (2 Yellow chromogenic properties such as -quinolyl) -2- (3-methoxy-4-n-dodecyloxyphenyl) ethene and 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene dye.

  Blue coloring dyes include 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-aminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-methylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3) -Yl) -3- (2-ethoxy-4-ethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dimethyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2) -Methylindol-3-yl) -3- (2-ethoxy-4-di-n-propylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-di-n-butylaminophenyl) -4-azaphthalide,

  3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-di-n-pentylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole) -3-yl) -3- (2-ethoxy-4-dihexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-) Diallylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl) -2-methylindol-3-yl) -3- (2-ethoxy-4-di-p-methoxycyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methyl) Indol-3-yl) -3- (2-ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-ethoxy- 4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2,3-diethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1 -Ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide,

  3- (1-Ethyl-2-methylindol-3-yl) -3- (2-chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-Chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-bromo-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3- Yl) -3- (2-ethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-propyl-) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl- 2-Methylindol-3-yl) -3- (2-nitro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-allyl) -4-diethylaminophenyl) -4-azaphthalide,

  3- (1-ethyl-2-methylindol-3-yl) -3- (2-hydroxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Cyano-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-cyclohexylethoxy-4-diethylaminophenyl) -4 -Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (2-cyclohexylethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (2-ethylindole-3-i ) -3- (2-Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-chloroindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4 -Azaphthalide, 3- (1-ethyl-2-bromoindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethylindole-3) -Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,

  3- (1-ethyl-2-n-propylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methoxyindole-3- Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethoxyindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl)- 4-Azaphthalide, 3- (1-ethyl-2-phenylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3 (2-Ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-ethyl-4,5,6,7-tetrachloro-2-methylindol-3-yl) -3- (2- Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-nitro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,

  3- (1-Ethyl-4-methoxy-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methylamino- 2-Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1- Chloro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-bromo-2-methylindo) Ru-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4-) Diethylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-propyl) -2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,

  3- (1-n-Butyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-butyl-2-indole-3) -Yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-pentyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylamino) Phenyl) -4-azaphthalide, 3- (1-n-hexyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n- Hexyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-octyl-2-methylindole- -Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylamino) Phenyl) -7-azaphthalide, 3- (1-n-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1- n-nonyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,

  3- (1-methoxy-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethoxy-2-methylindol-3-yl) -3- (2-Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-phenyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-n-pentyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-heptyl-2-methyl) Indol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-nonyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (4-dimethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3 -(1-Ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (p-dimethylaminophenyl) -6 -Blue coloring dyes such as dimethylaminophthalide.

  Examples of green coloring dyes include 3-dimethylamino-6-chloro-7-dibenzylaminofluorane, 3-dimethylamino-6-methyl-7-n-octylaminofluorane, 3-dimethylamino-7-di Benzylaminofluorane, 3-dimethylamino-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7-benzylaminofluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7- (N-cyclohexyl-N-benzylamino) fluorane, 3-diethylamino-6-methyl-7- ( 2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- (2-trifluorome Ruanilino) fluorane, 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (2-ethoxyanilino) fluorane, 3-diethylamino-6- Methyl-7- (4-ethoxyanilino) fluorane, 3-diethylamino-6-chloro-7-anilinofluorane,

  3-diethylamino-6-chloro-7- (2-chloroanilino) fluorane, 3-diethylamino-6-chloro-7-dibenzylaminofluorane, 3-diethylamino-6-ethoxy-7-anilinofluorane, 3- Diethylamino-7-anilinofluorane, 3-diethylamino-7-methylanilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-n-octylaminofluorane, 3-diethylamino- 7-p-chloroanilinofluorane, 3-diethylamino-7-p-methylphenylanilinofluorane, 3-diethylamino-7- (N-cyclohexyl-N-benzylamino) fluorane, 3-diethylamino-7- ( 2-chloroanilino) fluoran, 3-diethylamino-7 (3-trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-ethoxyanilino) fluorane, 3-diethylamino-7- ( 4-ethoxyanilino) fluorane, 3-diethylamino-7- (2-chlorobenzylanilino) fluorane,

  3- (N-ethyl-Nn-propyl) amino-6-chloro-7-dibenzylaminofluorane, 3- (N-ethyl-Nn-propyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-6-methyl-7-dibenzylaminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-6-methyl-7- (N-methyl-N-benzyl) aminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino -7- (N-methyl-N-phenyl) aminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7-dibenzylaminofluorane, 3-di-n-butylamino-6 -Chloro-7- (2 Chloroanilino) fluorane, 3-di-n-butylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-dibutylamino-6-methyl-7- (2-fluoroanilino) fluorane, 3-di- n-butylamino-7- (2-fluoroanilino) fluorane, 3-di-n-butylamino-7- (2-chloroanilino) fluorane,

  3-di-n-butylamino-7- (2-chlorobenzylanilino) fluorane, 3- (N-methyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-propyl- N-n-hexyl) amino-7-anilinofluorane, 3- (N-ethoxy-Nn-hexyl) amino-7-anilinofluorane, 3- (Nn-pentyl-N-allyl) Amino-6-methyl-7-anilinofluorane, 3- (Nn-pentyl-N-allyl) amino-7-anilinofluorane, 3- [p- (p-anilinoanilino) anilino] -6 Methyl-7-chlorofluorane, 3-anilino-7-dibenzylaminofluorane, 3-anilino-6-methyl-7-dibenzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane, 3- Piro Dino-7-cyclohexylanilinofluorane, 3-dibenzylamino-6-methyl-7-dibenzylaminofluorane, 3-dibenzylamino-7-dibenzylaminofluorane, 3-dibenzylamino-7- (2-chloroanilino) fluorane, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethyl A green coloring dye such as amino) phthalide.

  Examples of black coloring dyes include 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-7- (2-chloroanilino) fluorane, and 3-diethylamino-6. -Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7- (2-carbomethoxyphenyl) Amino) fluorane, 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluorane, 3- (N-cyclopentyl-N-ethyl) amino-6-methyl-7-phenylaminofur Oran, 3- (N-isoamyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-p-tolue) Dino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- (N-methyl-N-tetrahydrofluorine) Furyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7 -Phenylaminofluorane, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-dipentylamino-6-methyl-7- Anilinofluorane, 3-dipentylamino-6-methyl-7 anilinofluorane, 3- (n-ethyl-n-isoamyl) amino-6-methyl Ru-7-anilinofluorane, 3-diethylamino-6-methyl-7- (3-methylphenylamino) fluorane, 3- (n-ethyl-n-tolyl) amino-6-methyl-7-anilinofur There are black coloring dyes such as Oran. These dye precursors can be used alone or in combination of two or more as required.

  Some functional dye precursors have absorption in the near infrared region. When this dye precursor is used alone or in combination with other dye precursors for high-temperature color development, automatic reading with a near-infrared lamp that absorbs high-temperature color images in the near-infrared region is possible. Possible images can be obtained. When this dye precursor is used in the present invention, an image having an absorption only in the visible region, an image having an absorption in the near infrared region, and the like can be used in combination, and a recording material with high security can be obtained.

  As such a dye having absorption in the near infrared region, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5 , 6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetra Chlorophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3- [1,1-bis (P-diethylaminophenyl) ethylene-2-yl] -6-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3- [ p- (p-dimethylaminoanilino) Nilino] -6-methylfluorane, 3- [p- (p-dimethylaminoanilino) anilino] -6-methyl-7-chlorofluorane, 3- (pn-butylaminoanilino) -6 Methyl-7-chlorofluorane, 3- [p- (p-anilinoanilino) anilino] -6-methyl-7-chlorofluorane, 3- [p- (p-chloroanilino) anilino] -6-methyl-7- Chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6,8,8-trimethyl-9-ethyl-8,9-dihydro- (3,2, e) pyridfluorane, 3-di- n-Butylamino-6,8,8-trimethyl-8,9-dihydro- (3,2, e) pyridfluorane, 3'-phenyl-7-N-diethylamino-2,2'-spirobis- (2H-1 -Benzopyran) Bis (p- dimethylaminostyryl)-p-tri sulfonyl methane, 3,7-bis (dimethylamino) -10-benzoyl-phenothiazine, and the like. These electron donating dye precursors may be used alone or in combination of two or more as required.

  The electron-accepting compound used in the heat-sensitive color forming layer of the present invention is generally represented by a pressure-sensitive recording material or an acidic substance used in a heat-sensitive recording material, but is not limited thereto. For example, clay materials, phenol derivatives, aromatic carboxylic acid derivatives, N, N′-diallylthiourea derivatives, urea derivatives such as N-sulfonylurea, or metal salts thereof are used.

  Specific examples of such compounds include activated clay, zeolite, bentonite and other clay materials, 4-phenylphenol, 4-t-butylphenol, 4-hydroxyacetophenone, 2,2'-dihydroxydiphenyl, 2,2 ' -Methylenebis (4-methyl-6-tert-butylphenol), 4,4'-ethylenebis (2-methylphenol), 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxy) Phenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4 -Hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) -3-ethylhexane, 2 2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylpropane, 4 , 4'-dihydroxydiphenyl ether, 4,4'-cyclohexylidenebis (2-isopropylphenol), 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone,

  4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 4- Allyloxy-4′-hydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (3-chloro-4-hydroxyphenyl) sulfone, 2,4-bis (phenylsulfonyl) phenol, bis (3- Chloro-4-hydroxyphenyl) sulfide, 4,4′-thiobis (2-tert-butyl-5-methylphenol), 2,2′-bis (4-hydroxyphenylthio) diethyl ether, 1,7-bis ( 4-hydroxyphenylthio) -3,5-dioxaheptane, - (4-methyl-phenylsulfonyl) -N '- [3- (4-methylphenyl-sulfonyloxy) phenyl] urea,

  Phenolic properties such as dimethyl 4-hydroxyphthalate, 2,2-bis (4-hydroxyphenyl) acetic acid esters, alkyl esters of gallic acid, salicylanilide, 5-chlorosalicylanilide, novolac-type phenolic resins, modified terpenephenolic resins, etc. Compound, hydroxybenzoic acid ester such as ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, chlorobenzyl 4-hydroxybenzoate, benzoic acid, salicylic acid, 1 -Hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-di-t-butylsalicylic acid, 3,5-di-t -Nonyl Salici Acid, 3,5-didodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3,5-bis (α, α-dimethylbenzyl) salicylic acid, 3-methyl-5- (α-methylbenzyl) salicylic acid, 4-n-octyloxycarbonylaminosalicylic acid, 4- [2- (4-methoxyphenoxy) ethoxy] salicylic acid, tartaric acid, oxalic acid, boric acid, citric acid, atearic acid and other organic acids, or zinc, nickel, Well-known compounds such as metal salts such as aluminum and calcium, urea derivatives such as bis [4- (4-methylphenyl) sulfonylaminocarbonylaminophenyl] methane, and thiourea derivatives are not limited thereto. If necessary, they can be used alone or in combination of two or more.

  Coloring components such as a dye precursor and an electron accepting compound contained in the heat-sensitive color forming layer constituting the heat-sensitive recording material of the present invention are coated on a support and dried as a dispersion liquid dispersed in a dispersion medium. The dispersion is obtained by a method of dry pulverizing the compound constituting the color forming component and dispersing it in the dispersion medium, or a method of mixing the compound constituting the color forming component in the dispersion medium and wet pulverizing. Usually, the electron-accepting compound is contained at 10 to 200% by mass of the dye precursor.

  When these dye precursors are used in the form of dispersed particles, the average particle diameter of the dispersed particles is generally 0.5 μm or more and 5.0 μm or less, preferably in a sand mill, ball mill or the like using water as a dispersion medium. Is wet pulverized to 0.8 μm or more and 2.0 μm or less, and is applied in a single layer or multiple layers together with an electron-accepting compound and other additives. If the average particle size is too small, background fogging and background coloration (yellowing change) during long-term storage tend to occur. Conversely, if the average particle size is too large, the color development sensitivity is deteriorated. The average particle size of the electron-accepting compound is usually 7 μm or less, preferably 0.05 to 5 μm, particularly preferably 0.1 to 2 μm. By setting it within this range, it is possible to obtain a heat-sensitive recording material excellent in the whiteness of the heat-sensitive color developing layer and the color developability.

  The heat-sensitive color forming layer constituting the heat-sensitive recording material of the present invention can contain a heat-fusible compound 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 particularly preferred.

  Specific examples of such compounds include stearic acid amide, N-hydroxymethyl stearic acid amide, N-stearyl stearic acid amide, ethylene bis stearic acid amide, oleic acid amide, palmitic acid amide, methylene bis hydrogenated tallow fatty acid amide. , Fatty acid amides such as ricinoleic acid amide, paraffin wax, microcrystalline wax, polyethylene wax, carnauba wax and the like, and natural waxes, aliphatic urea compounds such as N-stearyl urea, 2-benzyloxynaphthalene, bis ( 4-methoxyphenyl) ether, 2,2'-bis (4-methoxyphenoxy) diethyl ether, 1,2-bis (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1,2-bis (phenoxy) Methyl) benze , Naphthyl ether derivatives, anthryl ether derivatives, ether compounds such as aliphatic ethers, diphenyl adipate, di (4-methylbenzyl) oxalate, dibenzyl oxalate, di (4-chlorobenzyl) oxalate, diphenyl carbonate, terephthalic acid Ester compounds such as dimethyl, dibenzyl terephthalate, benzenesulfonic acid phenyl ester, 4-acetylacetophenone, biphenyl derivatives such as m-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl, 4-allyloxybiphenyl, bis (4- Known thermofusible compounds such as allyloxyphenyl) sulfone, acetoacetanilide, 4-methylacetanilide, fatty acid anilides, etc. are mentioned, but are not limited to these, and if necessary, alone or 2 It can be used as a mixture or more.

  Moreover, when adding a thermofusible compound, the addition amount is 0.3-2 times by mass ratio with respect to the said electron-accepting compound, and a more preferable range is 0.5-1.5 times. It is. With this range, a heat-sensitive recording material having good basic characteristics such as thermal responsiveness, saturated density of color image, and whiteness of the background can be obtained.

  Moreover, in order to improve the preservability of a recording part, a preservability improving agent can also be contained. Specific examples of such preservability improvers include, for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-ethylenebis (4-methyl-6-tert-butylphenol), 2 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4,6-di-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert) -Butylphenol), 2,2'-ethylidenebis (4-ethyl-6-tert-butylphenol), 2,2'-isopropylidenebis (4,6-di-tert-butylphenol), 2,2'-methylenebis ( 4-methoxy-6-tert-butylphenol), 2,2'-methylenebis (6-tert-butylphenol), 4, '-Thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (5-methyl-6-tert-butylphenol) 4,4'-thiobis (2-chloro-6-tert-butylphenol), 4,4'-thiobis (2-methoxy-6-tert-butylphenol), 4,4'-thiobis (2-ethyl-6- tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α' -Bis (4 ″ -hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ' , 5,5'-tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) Hindered phenol compounds such as propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, N, N'- Examples include di-2-naphthyl-4-phenylenediamine, 2,2′-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate.

  Pigments used in the thermosensitive coloring layer according to the present invention are porous synthetic amorphous silica, colloidal silica, colloidal alumina, porous magnesium carbonate, porous aluminum hydrate, light calcium carbonate, calcined kaolin, aluminum hydroxide, Talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide White inorganic pigments such as styrene plastic pigments, acrylic plastic pigments, hydrocarbon plastic pigments, organic pigments such as urea resins and melamine resins. These pigments are also usually dispersed in an aqueous dispersion medium and blended in the recording layer coating liquid.

  In addition, for the purpose of improving thermal head matching properties such as sticking prevention and head wear prevention, higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearamide, caster wax, etc. Waxes, dispersants such as sodium dioctyl sulfosuccinate, ultraviolet absorbers such as benzophenone and benzotriazole, surfactants, fluorescent dyes and the like are added as necessary.

  In the present invention, it can also be applied to a multicolor thermosensitive recording material. When coating at least one of two or more electron-donating dye precursors with a color control layer obtained by addition polymerization of a vinyl monomer in order to improve color separation, it is for low temperature color development. Is used in the form of dispersed particles, and color separation is performed by coating high-temperature color development with a color adjustment layer, and low-temperature color development and high-temperature color development are both coated with color adjustment layers having different color sensitivity. There is a case. These low-temperature coloring dye precursors and high-temperature coloring dye precursors may be contained in a single layer, or if they are coated in multiple layers so that the low-temperature coloring dye precursor is an upper layer, further color separation can be achieved. Get better. In the case where both the low temperature coloring dye precursor and the high temperature coloring dye precursor are dispersed particles, they may be in the same layer, but from the viewpoint of color separation, the high temperature coloring dye precursor is placed in the lower layer. It is preferable to provide a multicolor thermosensitive coloring layer by arranging a low temperature coloring dye precursor in the upper layer. When laminated, bubbling tends to occur, but the occurrence is suppressed by the present invention. Further, at least one of two or more kinds of electron donating dye precursors can be isolated by encapsulating and solid composite fine particles. Covering at least one of the two or more dye precursors with a color adjusting layer obtained by addition polymerization of a vinyl monomer has an effect of improving color separation in multicolor thermal recording.

  The dye precursor for low-temperature color development used in the multicolor thermosensitive coloring layer according to the present invention is used in combination of one or more of those having a color tone of red to yellow or green to blue. However, since the color-added multicolor heat-sensitive recording material has a tendency that the color tone at a high temperature becomes a dark color due to the color mixture, a light red color to a yellow color are preferably used on the low temperature side. The high-temperature color forming dye precursor is used by appropriately combining at least one dye precursor that develops a dark color such as black, green, and blue.

  By coating the dye precursor in the present invention with the color adjusting layer, the color separation property in multi-color development is improved. The method of coating is to adjust the color around the dispersed particles by adding a vinyl monomer and a polymerization initiator to the dye precursor dispersion previously dispersed in a sand mill, ball mill, etc., and heating as necessary. A layer is formed and manufactured.

  The vinyl monomer includes a compound having one vinyl bond and a compound having two or more vinyl bonds. By changing the content of the compound having two or more vinyl bonds, it is possible to freely change the thermal sensitivity characteristics of the color forming control layer. Compared to those polymerized with only a compound having one vinyl bond, the color-adjusting layer using a compound having two or more vinyl bonds has a stronger cross-linking structure, and has a color development start temperature when it is used as a heat-sensitive recording material. Can be on the high temperature side. The combined ratio of the compound having two or more vinyl bonds is 1 to 70% by mass, preferably 10 to 50% by mass, based on the total mass of the vinyl monomer. Within this range, the color development characteristics such as the color development start temperature can be arbitrarily adjusted.

  The amount of the vinyl monomer with respect to the dispersed particles of the dye precursor is preferably 0.5% by mass or more and 1000% by mass or less, and within this range, the polymerization proceeds without agglomeration during polymerization, and the color development is controlled. A coating with sufficient function as a layer is obtained. In this manner, the heat sensitive property of the color adjusting layer can be adjusted by increasing or decreasing the amount of the vinyl monomer.

  Specific examples of the compound having only one vinyl bond in the present invention include styrene, α-methylstyrene, α-methoxystyrene, m-bromostyrene, m-chlorostyrene, o-bromostyrene, o-chlorostyrene, p -Bromostyrene, vinylidene cyanide, ethylene, propylene, vinyl chloride, vinyl acetate, acrolein, methyl acrolein, acrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, diacetone acrylamide, N-octadecylacrylamide, α-acetoxyacrylic Ethyl acetate, ethyl α-chloroacrylate, methyl α-chloroacrylate, methyl α-cyanoacrylate, methyl α-phenylacrylate, benzyl acrylate, butyl acrylate, ethyl acrylate, acrylic acid-2- Hexyl, vinyl ethyl sulfoxide, vinyl formate, vinyl isobutyl ether, vinyl laurate, and vinyl phenyl ether.

  Specific examples of the compound having two or more vinyl bonds include polyethylene glycol diacrylates such as ethylene glycol diacrylate and diethylene glycol diacrylate, polyethylene glycol dimethacrylates such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate, 2, 2,2-bis (4-acryloxypolyethoxyphenyl) propanes such as 2-bis (4-acryloxyethoxyphenyl) propane and 2,2-bis (4-acryloxydiethoxyphenyl) propane; 2,2-bis (4-methacryloxypolyethoxyphenyl) propanes such as bis (4-methacryloxyethoxyphenyl) propane and 2,2-bis (4-methacryloxydiethoxyphenyl) propane, allyl Chlorate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, triallyl isocyanurate, triallyl trimellitate, tetramethylolmethane tetraacrylate, tetramethylolmethanetetra And methacrylate.

  The vinyl monomers according to the present invention can be used alone or in combination of two or more. When two or more types are used in combination, as described above, a combination of a compound having one vinyl bond and a compound having two or more vinyl bonds is preferable. It can also be used in combination of two or more compounds.

  When some or all of these vinyl monomers are methacrylic acid esters, the methacrylic acid ester and the polymer thereof have good adhesion to the dye precursor dispersed particles provided with the color adjusting layer, and the aqueous dispersion medium. Therefore, it is possible to efficiently coat the surface of the dye precursor dispersed particles by addition polymerization. Furthermore, it is excellent in the function of adjusting the color development characteristics such as the color development start temperature, and is particularly preferably used in the present invention.

  A known polymerization initiator can be used for addition polymerization of the vinyl monomer, and the mode of the polymerization reaction is not limited to radical polymerization, anionic polymerization, cationic polymerization, etc., but radical polymerization is particularly preferably used. It is done. Further, the system may be heated as necessary during the polymerization. Specific examples of the polymerization initiator for radical polymerization are shown below. Peroxides such as hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, persulfates such as potassium persulfate, ammonium persulfate, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2, Azo compounds such as 2'-azobis (2-methylpropionamidine) dihydrochloride, 4,4'-azobis (4-cyanovaleric acid), a combination of hydrogen peroxide and ferrous salt, persulfate and sodium acid sulfite Combination of cumene hydroxyperoxide and ferrous salt, benzoyl peroxide and diethylaniline Align, combinations of peroxide and metal alkyl, redox initiators such as a combination of oxygen and an organic metal alkyl. These are not limited to single use, but may be used in combination.

  The polymerization initiator for radical polymerization is not particularly limited as long as it can generate active radicals by heat or light energy other than those described above, but the dye precursor and developer particles are dispersed in an aqueous dispersion medium. In this case, it is particularly preferable to use a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, or 2,2′-azobis (2-methylpropionamidine) dihydrochloride.

  The addition amount of the polymerization initiator is not particularly limited as long as the vinyl monomer starts addition polymerization, but in order to efficiently start the addition polymerization, the amount of polymerization initiator is set to 0. 001 mass% or more and 10 mass% or less are preferable.

The coating amount as the solid content of the dye precursor in the thermosensitive coloring layer according to the present invention is 0.2 to ² g / m ² , preferably 0.3 to 1.5 g / m ^2. Good and advantageous in terms of cost.

  In the present invention, the support on which the thermosensitive coloring layer is provided may be transparent, translucent, or opaque, and may be paper, various nonwoven fabrics, woven fabric, synthetic resin film, synthetic resin laminated paper, synthetic paper, metal foil, Ceramic paper, a glass plate, etc., or a composite sheet combining them can be arbitrarily used depending on the purpose.

  In the present invention, an intermediate layer may be provided between the thermosensitive coloring layer and the support in order to improve smoothness, heat insulation and the like. The intermediate layer can contain various resins, organic pigments, inorganic pigments, various hollow particles, and the like. In addition, the surface between the thermochromic layer and the support and / or the surface on which the thermochromic layer is provided, or the opposite surface includes a material capable of recording information electrically, magnetically, or optically. A layer, an ink jet recording layer, a thermal transfer image receiving layer, or the like may be provided. Further, a back coat layer may be provided on the surface opposite to the surface on which the thermosensitive coloring layer is provided for the purpose of preventing curling, preventing charging, etc., and further, an adhesive processing or the like may be performed. In addition, printing with UV ink, gravure ink, or the like may be performed on the surface of the thermosensitive coloring layer or the protective layer.

  For each of the layers other than the protective layer of the present invention, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, magnesium hydroxide are used for the purpose of improving device matching and whiteness, as necessary. , Titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, porous synthetic amorphous silica, colloidal silica, colloidal alumina, calcium sulfate, barium sulfate, titanium dioxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, silicic acid Mainly white inorganic pigments such as calcium, magnesium silicate, alumina, lithopone, zeolite, hydrous halloysite, monomers such as vinyl chloride, vinylidene chloride, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylonitrile, styrene Resin as a component or this Organic hollow particles whose core is a copolymer resin mainly composed of the above monomers, organic pigments having through-holes as disclosed in JP-A-5-222108, and openings as disclosed in JP-A-10-217608 In addition to organic pigments, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, polyethylene oxide, and castor wax, dispersants such as sodium dioctyl sulfosuccinate, A surfactant, a fluorescent dye, and the like can also be contained. In addition, in order to perform printing with laser light, a photothermal conversion material can be contained in any layer and support in monochromatic and multicolor thermosensitive recording materials.

  The formation method of each layer in the present invention is not particularly limited, and can be formed using a known technique. For example, each layer is formed by air knife coating, blade coating, varibar blade coating, curtain coating, or the like. can do. Furthermore, in order to improve the surface smoothness, various known techniques in the production of heat-sensitive recording materials can be used, such as the use of machines such as a machine calendar, super calendar, gloss calendar, and brushing.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, the ratio of parts and% is based on mass.

Example 1
The thermosensitive recording material of Example 1 was produced as follows.

(1) Preparation of intermediate layer coating solution An intermediate layer coating solution comprising the following components was prepared.
Sodium hexametaphosphate 10% aqueous solution 10 parts Calcined kaolin (Engelhard, Ansilex) 100 parts Oxidized starch 12% aqueous solution 50 parts SBR latex 48% aqueous dispersion 25 parts water 79 parts

(2) Formation of intermediate layer The intermediate layer coating solution prepared in (1) was applied to a high-quality paper of 50 g / m ^{2 with} a blade coater and dried so that the solid content was 9 g / m ^2. Formed.

(3) Preparation of coating solution for thermosensitive coloring layer A solution, B solution, C solution and D solution having the following composition were prepared.
(Liquid A)
A liquid having the following composition was pulverized to a volume average of 1.0 μm using Dynomill (manufactured by Shinmaru Enterprises).
Polyvinyl alcohol 10% aqueous solution 100 parts (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gocelan L3266)
3-dibutylamino-6-methyl-7-anilinofluorane 100 parts water 75 parts (liquid B)
Liquid B was prepared in the same manner as liquid A except that 3-di-n-butylamino-6-methyl-7-anilinofluorane in liquid A was changed to bis (3-allyl-4-hydroxyphenyl) sulfone. .
(C liquid)
Liquid C was prepared in the same manner as liquid A except that 3-di-n-butylamino-6-methyl-7-anilinofluorane in liquid A was changed to 2-benzyloxynaphthalene.
(Liquid D)
Sodium metametaphosphate 10% aqueous solution 69 parts Aluminum hydroxide 230 parts Zinc stearate 50% aqueous dispersion 150 parts

A coating liquid having the following composition using the liquid A, liquid B, liquid C and liquid D obtained above was stirred and mixed to prepare a coating liquid for a thermosensitive coloring layer.
A liquid 275 parts B liquid 550 parts C liquid 550 parts D liquid 250 parts Polyvinyl alcohol 10% aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol NM-11, saponification degree 99.0 mol% or more, polymerization degree 1100) 1200 200 parts water

(4) Preparation of Coating Liquid 1 for Protective Layer A coating liquid 1 having the following composition was stirred and mixed to prepare a protective layer coating liquid 1.
Polydiallyldimethylammonium chloride (molecular weight 20,000) 20% solution 0.15 parts colloidal silica (Nissan Chemical Industries, Snowtex AKL 20%)
300 parts polyvinyl alcohol 10% aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol NM-11, saponification degree 99.0 mol% or more, polymerization degree 1100) 200 parts zinc stearate 50% aqueous dispersion 8 parts glyoxal 40% 5 parts of solution

(5) Formation of thermosensitive coloring layer The above thermosensitive coloring layer coating solution was coated on the support so that the amount of the dye precursor applied was 0.70 g / m ² and dried to provide a thermosensitive coloring layer. .

(6) Formation of protective layer The protective layer coating liquid 1 is coated on the heat-sensitive coloring layer obtained above so that the coating amount is 3.0 g / m ² and dried to provide a protective layer. It was. This was calendered so as to have a Beck smoothness of 1000 to 3000 seconds to obtain a heat-sensitive recording material of Example 1.

Example 2
The heat-sensitive recording material of Example 2 was obtained in the same manner as in Example 1 except that the 20% polydiallyldimethylammonium chloride (molecular weight: 20,000) solution of Example 1 was changed to 0.15 parts with a molecular weight of 2000. It was.

Example 3
A thermosensitive recording material of Example 3 was obtained in the same manner as in Example 1 except that the 20% polydiallyldimethylammonium chloride (molecular weight: 20,000) solution of Example 1 was changed to 30 parts with a molecular weight of 140,000. .

Example 4
A heat-sensitive recording material of Example 4 was obtained in the same manner as in Example 1 except that the 20% polydiallyldimethylammonium chloride (molecular weight: 20,000) solution of Example 1 was changed to 30 parts with a molecular weight of 200,000. .

Example 5
Except for changing to a polyvinyl alcohol 10% aqueous solution of Example 1 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol NL-05, saponification degree of 98.5 mol% or more, polymerization degree of 500), the same as in Example 1 A heat-sensitive recording material of Example 5 was obtained.

Example 6
Example 1 except that the polyvinyl alcohol 10% aqueous solution of Example 1 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol KL-05, saponification degree 78.5-82.0 mol%, polymerization degree 500) was used. Similarly, the heat-sensitive recording material of Example 6 was obtained.

Example 7
The same as Example 1 except that the colloidal silica of Example 1 (Nissan Chemical Industry Co., Ltd., Snowtex AKL 20%) was changed to colloidal silica (Nissan Chemical Industry Co., Ltd., Snowtex C 20%). Thus, a heat-sensitive recording material of Example 7 was obtained.

Comparative Example 1
A thermosensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the 20% solution of polydiallyldimethylammonium chloride (molecular weight 20,000) was removed from Example 1.

Comparative Example 2
A heat-sensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that colloidal silica was removed from Example 1.

Comparative Example 3
A thermosensitive recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the 10% polyvinyl alcohol solution was removed from Example 1.

Comparative Example 4
Except that the 20% solution of polydiallyldimethylammonium chloride (molecular weight: 20,000) in Example 1 was changed to a dimethylaminoethyl methacrylate quaternized 20% solution (Sensa Co., Ltd. Unisense FPV1000L), the same as in Example 1, A heat-sensitive recording material of Comparative Example 4 was obtained.

  The thermosensitive recording materials produced in Examples 1 to 7 and Comparative Examples 1 to 4 were subjected to the following evaluation.

Evaluation 1 [Barrier property to organic solvent]
Rub the surface of the white paper sample with 4 parts of toluene and 6 parts of ethyl acetate mixed with 5 ml of solvent, and rub it 5 times with a weak force, and visually check the degree of fogging (coloring degree) with the treated solvent. And evaluated.
Evaluation criteria) ○: No color development.
Δ: Slight color development but usable level.
X: Coloring is severe and unusable level.

Evaluation 2 [Ink adhesion]
Pretreatment Using a general-purpose gravure ink (CCST series manufactured by Toyo Ink Manufacturing Co., Ltd.), a fine line grid pattern was printed with a gravure printing machine and cured in a dryer at 40 ° C. for 24 hours.
Evaluation Water at 20 ° C. is dropped on the printed surface after the treatment, and the printed surface on which the water is adhered is rubbed 30 times with a weak force so as to draw a circle having a diameter of 3 cm with an index finger. The remaining degree of printing at this time was visually evaluated.
Evaluation criteria) ○: No printing failure.
Δ: Almost no printing omission. (Printing begins to drop after 20 or more finger rubs) ×: Printing is missing. (Printing starts less than 20 times with finger rubs, and the printed part disappears completely.)

Evaluation 3 [Color density]
Printing was performed with an applied energy of 0.35 mJ / dot using a printing test machine (TH-PMD) manufactured by Okura Engineering Co., Ltd. The printing density at that time was measured using a reflection densitometer (RD-19I) manufactured by Gretag Macbeth. There is no problem if the print density is 1.25 or more. The evaluation results are shown in Table 1.

  As is clear from the results in Table 1, Examples 1 to 7 are all the contents of the present invention, ensuring a color density, good organic solvent barrier properties, good ink adhesion, and a balance of properties. It is taken. On the other hand, Comparative Example 1 containing no polydiallyldimethylammonium chloride had poor organic solvent barrier properties. Further, Comparative Example 2 excluding colloidal silica had poor ink adhesion. Comparative Example 3 excluding polyvinyl alcohol had poor organic solvent barrier properties. In Comparative Example 4 in which polydiallyldimethylammonium chloride was changed to dimethylaminoethyl methacrylate quaternized product, the barrier property against organic solvent was insufficient.

Claims (3)

  A thermosensitive recording material comprising a support and a thermosensitive coloring layer and a protective layer in this order, wherein the protective layer contains polyvinyl alcohol, colloidal silica, and polydiallyldimethylammonium chloride. .   The heat-sensitive recording material according to claim 1, wherein in the protective layer, the molecular weight of polydiallyldimethylammonium chloride is 10,000 to 250,000.   The heat-sensitive recording material according to claim 1, wherein in the protective layer, polydiallyldimethylammonium chloride is 0.0003 to 15.0 parts by mass with respect to 100 parts by mass of colloidal silica.