JP2020131452A - Heat-sensitive recording material - Google Patents

Abstract

To provide a heat-sensitive recording material that is excellent in elasticity, color development, waterproof coating strength, and coating strength during expansion and contraction.SOLUTION: A heat-sensitive recording material has a thermosensitive recording layer on an elastic support, the thermosensitive recording layer containing a developer having three or more aromatic rings in the molecule, and a urethane resin with a glass transition temperature of less than 10°C.SELECTED DRAWING: None

Description

The present invention relates to a heat-sensitive recording material having excellent elasticity, color development, water-resistant coating layer strength, and coating layer strength during expansion and contraction.

The heat-sensitive recording material generally contains an electron-donating dye precursor (hereinafter referred to as a dye precursor) and an electron-accepting color developer (hereinafter referred to as a color developer) on a support as main components. A heat-sensitive recording layer is provided, and by heating with a heat head, a heat pen, a laser beam, or the like, the dye precursor and the color developer instantly react with each other to obtain a recorded image.

For example, Japanese Patent Application Laid-Open No. 2013-212672 (Patent Document 1) describes a thermal recording material using synthetic paper as a support. Thermal recording materials using synthetic paper or synthetic resin film as a support are excellent in water resistance, and are therefore suitable as output media for various applications such as food label applications and medical applications. Is increasing.

In hospitals, etc., patient identification data such as the patient's name, blood type, and bar code indicating the patient ID can be displayed on a wristband and attached to the patient's wrist or ankle to manage and identify the patient. It is done. When using a thermal recording material for recording patient (individual) identification data, there is an advantage that it can be recorded in a short time and at low cost even if the lot is small, and a heat melt transfer method, a heat sublimation transfer method, etc. are used. Since the transfer ribbon is not used unlike the recording material, the patient (individual) identification data is not leaked from the waste, which is suitable.

It is desirable to impart elasticity to the heat-sensitive recording material used for such applications from the viewpoint of reducing the burden (discomfort) of the patient. Further, in the above-mentioned use of food labels, they may also be used for foods having a curved surface (for example, fruits and vegetables such as fruits), and the heat-sensitive recording material is required to have high elasticity. Therefore, there has been a demand for a heat-sensitive recording material having good elasticity and excellent coating layer strength during expansion and contraction (the coating layer does not peel off or crack).

A heat-sensitive recording material using an olefin-acrylic acid-based copolymer salt or a styrene-butadiene copolymer as a binder component of the heat-sensitive recording layer for the purpose of increasing the strength of the water-resistant coating layer is described in Patent Document 1 and JP-A-2014. It is described in Japanese Patent Application Laid-Open No. 148120 (Patent Document 2). However, the water-resistant coating layer strength of the heat-sensitive recording material containing an olefin-acrylic acid-based copolymer salt or a styrene-butadiene copolymer in the heat-sensitive recording layer is not sufficiently satisfactory, and the elasticity and the coating layer at the time of expansion and contraction are not sufficiently satisfactory. It was not sufficiently satisfactory in terms of strength.

A heat-sensitive recording material using urethane resin as a binder component of the heat-sensitive recording layer for the purpose of improving the water-resistant coating layer strength and the coating layer strength of the heat-sensitive recording material is described in, for example, Japanese Patent Application Laid-Open No. 2009-45760 (Patent Document 3). In Japanese Patent Application Laid-Open No. 2004-314405 (Patent Document 4), it is described that the image preservation property can be improved by setting the glass transition temperature of a specific polyurethane resin contained in the heat-sensitive recording layer to 10 ° C. or higher. Has been done. However, these heat-sensitive recording materials are not sufficiently satisfactory in terms of elasticity and coating layer strength during expansion and contraction, and are also not satisfactory in terms of color development.

Japanese Unexamined Patent Publication No. 2013-212672 Japanese Unexamined Patent Publication No. 2014-148120 JP-A-2009-45760 Japanese Unexamined Patent Publication No. 2004-314405

An object of the present invention is to provide a heat-sensitive recording material having excellent elasticity, color development, water resistance coating layer strength, and coating layer strength during expansion and contraction.

The above-mentioned problems are solved by the following inventions.
It is characterized by having a heat-sensitive recording layer on an elastic support, and the heat-sensitive recording layer contains at least a color developer having three or more aromatic rings in the molecule and a urethane resin having a glass transition temperature of less than 10 ° C. Thermal recording material.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a heat-sensitive recording material having excellent elasticity, color development property, water-resistant coating layer strength, and coating layer strength during expansion and contraction.

As described above, it has been conventionally known that synthetic paper or synthetic resin film is used as a support for the thermal recording material, or that the thermal recording layer contains urethane resin, but such thermal recording material expands and contracts. It was not sufficiently satisfactory in terms of properties, color development, water-resistant coating layer strength, and coating layer strength during expansion and contraction. As a result of diligent studies on this subject, the present inventor uses an elastic support, a color developer whose heat-sensitive recording layer has three or more aromatic rings in the molecule, and a glass transition temperature (hereinafter referred to as Tg). The present invention has been found that a heat-sensitive recording material having excellent elasticity, color development, water-resistant coating layer strength, and coating layer strength at the time of expansion and contraction can be obtained by containing at least a urethane resin having a temperature of less than 10 ° C. It came to.

Hereinafter, the contents of the present invention will be specifically described.

The heat-sensitive recording material of the present invention has an elastic support. The stretchable support in the present invention means a support having a tensile elongation of 200% or more and a recovery rate at 200% elongation of 90% or more measured by the methods shown below.

[Tensile elongation (%)]
The tensile elongation is measured in an environment of 23 ° C. and 65% RH using a single column type material tester STA-1150 manufactured by Orientec Co., Ltd. Specifically, a sample is cut into strips having a length of 150 mm and a width of 10 mm in the measurement direction, and the initial tension chuck distance is 50 mm and the tension speed is 200 mm / min, according to the method specified in JIS K-7127 (1999). The measurement is performed 10 times, and the average value is taken as the tensile elongation. The sample is changed for each measurement.

[Recovery rate at 200% elongation (%)]
Using a single column type material tester STA-1150 manufactured by Orientec Co., Ltd., the recovery rate at 200% elongation is measured in an environment of 23 ° C. and 65% RH. Specifically, a sample is cut into strips having a length of 150 mm and a width of 10 mm in the measurement direction, and both ends of the central portion of the measurement direction having a length of 50 mm are marked with a water-based pen, an oil-based pen, or the like. The initial tension chuck distance is 50 mm, stretched 200% (100 mm) at a speed of 200 mm / min, held for 10 seconds, then the stretch strain is released at a speed of 450 mm / min, and the distance between marks before stretching (L0, 50 mm). ), The distance between the marks after elongation (L1, 150 mm) and the distance between the marks after the extension strain is released (L2) are measured with a caliper, and the recovery rate at the time of 200% extension is calculated by the following formula. This measurement is performed 10 times, and the average value is taken as the recovery rate at 200% elongation. The sample is changed for each measurement.
Recovery rate at 200% elongation (%) = {(L1-L2) / (L1-L0)} x 100

Examples of the stretchable support having a tensile elongation of 200% or more and a recovery rate at 200% of 90% or more include thermoplastics such as polyurethane elastomers, polyester elastomers, polystyrene elastomers, polyolefin elastomers, and polyamide elastomers. Examples include films containing elastomers. The thickness is 10 μm to 400 μm, preferably 30 μm to 300 μm. Commercially available products such as these can be used. For example, commercially available products under product names such as Higres (registered trademark) DUS202 and Higres DUS501 can be obtained and used from Seadam Co., Ltd. It is possible.

The heat-sensitive recording layer of the heat-sensitive recording material of the present invention contains a urethane resin having a Tg of less than 10 ° C. In the present invention, since the heat-sensitive recording layer contains a urethane resin having a Tg of less than 10 ° C., a heat-sensitive recording material having good elasticity, water-resistant coating layer strength, and coating layer strength during expansion and contraction can be obtained. On the other hand, when the heat-sensitive recording layer contains a urethane resin having a Tg of 10 ° C. or higher, the heat-sensitive recording layer becomes brittle, so that the coating layer may peel off or crack during expansion and contraction.

The urethane resin described above can be obtained by reacting a dihydric alcohol, which is usually a bifunctional isocyanate, with a diisocyanate and a chain extender. The dihydric alcohol (or polyol), diisocyanate (or polyisocyanate), chain extender, cross-linking agent and the like used as the raw material of the urethane resin in the present invention are not particularly limited. The typical ones used industrially are described below.

As the dihydric alcohol (or polyol), a polyether compound or a polyester compound is generally used. Examples of the polyether compound include polyoxyethylene glycol, polyoxypropylene glycol and polyoxytetramethylene glycol, and examples of the polyester compound include polyoxyethylene adipate and polyoxypropylene adipate. In addition, acrylic polyol, castor oil and the like are used.

Aromatic diisocyanates, aliphatic diisocyanates and the like are generally used as diisocyanates (or polyisocyanates). Aromatic diisocyanates include tolylene diisocyanate, phenylenediisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, etc., and aliphatic diisocyanates include hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, etc. Can be mentioned. The chain extenders and cross-linking agents include polyol-based ethylene glycol, propylene glycol, butanediol, hexanediol, diethylene glycol, glycerin, trimethylolpropane and other polyamine-based hydrazines, ethylenediamine, propylenediamine, diethylenetriamine, 4,4'-. Examples thereof include diaminodiphenylmethane and 4,4'-diaminodicyclohexylmethane, but the present invention is not limited thereto.

The urethane resin is produced by a known method, for example, in a solvent at a reaction temperature of 20 to 150 ° C. in the presence of a catalyst or in the absence of a catalyst. Examples of the solvent used in this case include ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate. Further, as a catalyst for accelerating the reaction, amines, organotin compounds and the like are used.

Further, in the present invention, a commercially available urethane resin can also be used. For example, commercially available products under product names such as Hydran (registered trademark) AP-201 and Hydran AP-70 are obtained and used from DIC Corporation. It is also possible to do. In the effect of the present invention, there is no lower limit of Tg, but if Tg is lower than -15 ° C, sticking resistance and head residue may deteriorate. Therefore, it is desirable that the lower limit of Tg is -15 ° C or higher. ..

These urethane resins may be used alone or in combination of two or more.

The thermal recording layer of the thermal recording material of the present invention contains a color developer having three or more aromatic rings in the molecule. By containing the color developer, a heat-sensitive recording material having excellent color-developing property can be obtained. The reason is presumed as follows. When the heat-sensitive layer contains a urethane resin, it has a high affinity with a color developer, a dye precursor, and a color former, so that the color developability is likely to decrease. Further, the lower the Tg of the urethane resin, the more the interaction between the dye and the color developer disappears due to the influence of the thermal motion of the resin component in the heat-sensitive recording layer, and the color development property tends to be lowered. However, it is considered that the color developer having three or more aromatic rings in the molecule is less likely to be adversely affected by the deterioration of the color development property of the urethane resin. In the present invention, in the case of an aromatic ring in which a plurality of aromatic rings are condensed, such as a naphthalene ring and an anthracene ring, the number of aromatic rings is treated as one.

Specific examples of the color developer having three or more aromatic rings in the molecule used in the present invention include 4,4'-(1-phenylethylidene) diphenol, 3,5-di-α-methylbenzyl salicylic acid, and the like. 3,3'-(4,4'-methylenediphenyl) bis (ureido-p-trissulfone), 2,4-bis (phenylsulfonyl) phenol, 4,4'-{oxybis (ethyleneoxy-p-phenylenesulfonyl) )} Diphenol, 4-{[4- (2-methylbenzyloxy) phenyl] sulfonyl} phenol, 4- [4- (2-methylbenzyloxy) phenylsulfonyl] phenol, 4- (3-methylbenzyloxy) Phenyl-4'-hydroxyphenylsulfone, 4- (4-methylbenzyloxy) phenyl-4'-hydroxyphenylsulfone, 2,4-bis (p-tolylsulfonyl) phenol, 2,4-bis (phenylsulfonyl)- 5-Methylphenol, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 2,6-bis [(2-hydroxy-4-methylphenyl) ) Methyl] -4-methylphenol, 2,6-bis [(2-hydroxy-4-tert-butylphenyl) methyl] -4-tert-butylphenol, 1,3-bis [2- (p-hydroxyphenyl) -2-propyl] benzene, 1,3-bis [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-bis [2- (p-hydroxyphenyl) -2-propyl] benzene , 4-Hydroxy-4'-benzyloxydiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 4- [4- (4- {4- [4- (isopropoxy) phenylsulfonyl] phenoxy} butoxy ) Phenylsulfonyl] phenol, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,1,3-tris (5-cyclohexyl-4-hydroxy-ο-tril) ) Butane, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 4,4', 4 "- (butane-1,1,3-triyl) Tris (2-tert-butyl-5-methyl-4,1-phenylene) Tris [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanoate], 2,2'-methire Sulfone [2- (2H-benzotriazole-2-yl) -4-tert-dodecanylphenol], 2,2'-methylenebis [6- (2H-1,2,3-benzotriazole-2-yl)- 4- (2-Hydroxyethyl) phenol], 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone, 3- (3-tosyl ureido) phenyl-p-toluenesulfonate, N- [2- (3-phenylureido) phenyl] benzenesulfonamide, 1,5- (3-oxopentylene) bis {3'-[3'-(p-toluenesulfonyl) ureido] benzoate}, N- (2-{[(4-Methylphenyl) carbamoyl] amino} phenyl) benzenesulfonamide, 4-methyl-N- {2-[(phenylcarbamoyl) amino] phenyl} benzenesulfonamide, 4-methyl-N-( 2-{[(4-Methylphenyl) carbamoyl] amino} phenyl) benzenesulfonamide, 3,3'-(4,4'-methylenediphenyl) bis (ureido p-trissulfone), bis {3- [3' Derivatives of-(p-toluenesulfonyl) ureido] benzoate} and the like can be mentioned, but the present invention is not limited to these, and these color-developing agents may be contained alone or in combination of two or more. it can.

Among the color developers having three or more aromatic rings, 3- (3-tosylureido) phenyl-p-toluenesulfonate, N- [2- (3-phenylureido) phenyl] benzenesulfonamide, and 2,4 -A color developer having three aromatic rings, such as bis (phenylsulfonyl) phenol, is preferable because it is particularly excellent in color development.

In the present invention, in order to obtain sufficient color development, the total amount of the color developer having three or more aromatic rings in the molecule is preferably 15% by mass or more in the total solid content of the thermal recording layer. ..

In the present invention, the thermal recording layer contains a dye precursor together with the above-mentioned color developer. The dye precursor contained in the heat-sensitive recording layer is generally represented by a pressure-sensitive recording material or a dye precursor used for a heat-sensitive recording material, but one or more of them are used in an appropriate combination. Specific examples include those listed below, but the present invention is not limited thereto.

As black dye precursors, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di-n-pentylamino-6-methyl-7-anilinofluorane, 3 -Diethylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6 -Methyl-7-xylidinofluorane, 3-diethylamino-7- (2-carbomethoxyphenylamino) fluorane, 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluorane, 3- (N-cyclopentyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-4-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-4-toluidino) -6-methyl-7- (4-toluidino) fluorane, 3- (N) -Methyl-N-tetrahydrofurfuryl) Amino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7- (4-) n-butylphenylamino) fluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isopentyl) amino-6-methyl-7-anilinofluorane,

As red dye precursors, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide and 3,3-bis (1-n-butyl-2-methylindol-3) -Il) 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-methylindole-3-yl) phthalide, 3,3-bis Bis (1-methyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-propyl-2-yl) Methylindole-3-yl) phthalide, 3,3-bis (2-methylindole-3-yl) phthalide, Rhodamine B-anilinolactam, Rhodamine B- (o-chloroanilino) lactam, Rhodamine B- (p-nitroanilino) ) Lactam, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-6-methyl Fluolan, 3-diethylamino-6-methyl-7-chloro-8-benzylfluolane, 3-diethylamino-6,7-dimethylfluorane, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-7 -Chlorofluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7- (N-acetyl-N-methyl) aminofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7- n-propoxyfluorane, 3-diethylamino-7-p-methylphenylfluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylaminobenzo [a] fluorane, 3-diethylaminobenzo [c] fluorane, 3 -Dimethylamino-7-Methylfluorane, 3-dimethylamino-6-methyl-7-chlorofluorine, 3-dimethylamino-7-methylfluorane, 3-dimethylamino-7-chlorofluorine, 3-( N-ethyl-p-toluidino) -7-methylfluorane, 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-Nn-octyl) amino-6-methyl-7- Chlorofluorane, 3- (N-ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-Nn-octyl) amino-7-methylfluorane, 3- (N-Ethyl-Nn-Octyl) Amino-7-Chlorofluorane, 3- (N-Ethyl-N-4-Methylphenyl) Amino-7,8-Benzofluorane, 3- (N-ethoxyethyl) -N-Ethyl) Amino-7,8-Benzofluorane, 3- (N-Ethyl-N-Ethyl) Amino-7-Chlorofluorane, 3-n-dibutylamino-6-Methyl-7-Chloroflu Olan, 3-n-dibutylamino-7,8-benzofluorine, 3-n-dibutylamino-7-chlorofluorane, 3-n-dibutylamino-7-methylfluorane, 3-diallylamino-7, 8-Benzofluorane, 3-diallylamino-7-chlorofluorine, 3-di-n-butylamino-6-methyl-7-bromofluorine, 3-cyclohexylamino-6-chlorofluorine, 3-pyrroli Dylamino-7-methylfluorane, 3-ethylamino-7-methylfluorane, 3- (N-ethyl-N-isoamyl) amino-benzo [a] fluorane, 3-n-dibutylamino-6-methyl- 7-Bromofluorane, 3,6-bis (diethylaminofluorane) -γ- (4'-nitro) anilinolactam,

Green dye precursors include 3- (N-ethyl-Nn-hexyl) amino-7-anilinofluorane and 3- (N-ethyl-N-p-tolyl) amino-7- (N). -Phenyl-N-methyl) aminofluorane, 3- (N-ethyl-N-n-propyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-N-n-propyl) amino-6 -Chloro-7-dibenzylaminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7- (N-methyl-N-phenyl) aminofluorane, 3- (N-ethyl-4) -Methylphenyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-4-methylphenyl) amino-6-methyl-7-dibenzylaminofluorane, 3- (N-ethyl-4-methyl) Phenyl) amino-6-methyl-7- (N-methyl-N-benzyl) aminofluorane, 3- (N-methyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-) Propyl-Nn-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-di-n-butylamino-6-chloro- 7- (2-chloroanilino) fluorane, 3-di-n-butylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-di-n-butylamino-6-methyl-7- (2-fluoro) Anilino) fluorane, 3-n-dibutylamino-7- (2-chloroanilino) fluorane, 3-di-n-butylamino-7- (2-chlorobenzylanilino) fluorane, 3,3-bis (4-) Diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-(6'-dimethylamino) phthalide, 3-diethylamino-6-methyl-7-benzyl Aminofluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7- (N-) Cyclohexyl-N-benzyl) aminofluorane, 3-diethylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl- 7- (2-Trifluoromethylanilino) 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- (2-chloroanilino) fluorane, 3-diethylamino-6-chloro-7-di Benzylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-ethylethoxy-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-benzyl) aminofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 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-dimethylamino-6-chloro-7-dibenzylaminofluorane, 3-dimethylamino-6-methyl -7-n-octylaminofluorane, 3-dimethylamino-7-dibenzylaminofluorane, 3-dimethylamino-7-n-octylaminofluorane, 3-di-n-butylamino-7- (2) -Fluoroanilino) Fluoran, 3-anilino-7-dibenzylaminofluorane, 3-anilino-6-methyl-7-dibenzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane, 3-pyrrolidino -7- (4-Cyclohexylanilino) fluorane, 3-dibenzylamino-6-methyl-7-dibenzylaminofluorane, 3,7-bis (dibenzylamino) fluorane, 3-dibenzylamino-7- (2-Chloroanilino) Fluoran,

Blue dye precursors include 3- (1-ethyl-2-methylindole-3-yl) -3- (4-diethylaminophenyl) phthalide and 3- (1-ethyl-2-methylindole-3-). Il) -3- (2-Methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-aminophenyl)- 4-azaphthalide, 3- (1-ethyl-2-methylindole-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-methylindole-3-yl) -3- (2-ethoxy-4-yl) Dimethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-) 2-Methylindole-3-yl) -3- (2-ethoxy-4-di-n-propylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3 -(2-ethoxy-4-di-n-butylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n) -Pentylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n-hexylaminophenyl) -4-azaphthalide, 3 -(1-Ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dichloroaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dibromoaminophenyl)- 4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dialylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole) -3-yl) -3- (2-ethoxy-4-dimethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n-propoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-) Methylindole-3-yl) -3- (2-ethoxy-4-di-n-butoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3-( 2-ethoxy-4-di-n-hexyloxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-methylcyclohexyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-methoxycyclohexylaminophenyl) -4-azaphthalide, 3- (1) -Ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3 -(3-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2,3-diethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindole-3-yl)
-3- (4-Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-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-methylindole-3-yl) -3- (3-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-propyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-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-Il) -3- (2-allyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-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-methyl) Indol-3-yl) -3- (2-cyclohexylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-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-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-chloroindole-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl -2-Bromoindole-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-propylindole-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-ethoxyindole-3-yl) -3- ( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-phenylindole-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-methylindole-3-yl) -3 -(2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-ethyl-4,5,6,7-tetrachloro-2-methylindole-3-yl) -3- (2) −ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-nitro-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide , 3- (1-ethyl-4-methoxy-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methylamino) -2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methyl-2-methylindole-3-yl) -3 -(2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1) −Chloro-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-bromo-2-methylindole-3-yl) -3-( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1) -Methyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindole-3-yl) -3- ( 2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-propyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-butyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-butyl-2-indole-3) -Il) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-pentyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylamino) Phenyl) -4-azaphthalide, 3- (1-n-hexyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-) Hexyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide , 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-n-nonyl-2-) Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methoxy-2-methylindole-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethoxy-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-phenyl- 2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-pentyl-2-methylindole-3-yl) -3- (2) −ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-heptyl) -2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-nonyl-2-methylindole-3-yl) -3-( 2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-dimethylamino-2-methylphenyl) -3- (4-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (4-diethylamino-2-n-hexyloxyphenyl) -4- Examples include azaphthalide. These can be contained alone or in combination of two or more.

In addition, some functional dye precursors have absorption in the near infrared region. When this dye precursor is contained as a dye precursor for high-temperature color development alone or in combination with other dye precursors, the high-temperature color-developed image is automatically read in near-infrared light with absorption in the near-infrared region. Can be an image that can be used. When the heat-sensitive recording layer in the present invention contains this dye precursor, it is possible to use an image having absorption only in the visible region, an image having absorption in the near infrared region, and the like, and it is possible to obtain a recording material with high security. it can.

Examples of such dye precursors having absorption in the near infrared region include 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 -Tetrachlorophthalide, 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) anilino] -6-methylfluorane, 3- [p- (p-dimethylaminoanilino) anilino] -6-methyl-7-chlorofluorine, 3-( pn-butylaminoanilino) -6-methyl-7-chlorofluorine, 3-[p-(p-anilinoanilino) anilino] -6-methyl-7-chlorofluorine, 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) pyridofluorane, 3-di (n-butyl) amino-6,8,8-trimethyl-8,9-dihydro- (3,2, e) pyridofluorane, 3'-phenyl-7-N- Examples thereof include diethylamino-2,2'-spirology (2H-1-benzopyran), bis (p-dimethylaminostyryl) -p-trisulfonylmethane, 3,7-bis (dimethylamino) -10-benzoylphenothiazine. These dye precursors may be contained alone or in combination of two or more, if necessary.

In order to obtain sufficient thermal responsiveness, the total amount of dye precursors in the total solid content of the thermal recording layer is preferably 1 to 20% by mass.

As the color developer contained in the heat-sensitive recording layer in the present invention, in addition to the color-developing agent having three or more aromatic rings in the molecule, a known pressure-sensitive recording material is used as long as the effect of the present invention is not impaired. , Or a color developer used in a heat-sensitive recording material can be contained, but is not particularly limited.

4,4'-Dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-propoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-allyloxy Diphenylsulfone, 4-hydroxy-4'-octyloxydiphenylsulfone, 4-hydroxy-4'-dodecyloxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 3,4-dihydroxy-4'-methyl Diphenylsulfone, p-phenylphenol, p-hydroxyacetophenone, 1,1-bis (p-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) Hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxy) Phydroxy) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 4,4'-dihydroxydiphenyl ether, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfide, 2, , 2-bis (4-hydroxyphenyl) methyl acetate, 2,2-bis (4-hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-tert-butyl-5-methylphenol), 4-hydroxyphthal Dimethyl acid, benzyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, benzyl benzoate, stearyl benzoate, salicylanilide, 5-chlorosalitylanilide, salicylic acid, 3,5-di-tert-butylsalicylic acid, 4-[ 2'-(4-methoxyphenoxy) ethyloxy] salicylic acid, 3- (octyloxycarbonylamino) salicylic acid or a metal salt of these salicylic acid derivatives, N- (4-hydroxyphenyl) -p-toluenesulfonamide, N- (4-) Hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -1-naphthalenesulfonamide, N- (4-hydroxyphenyl) -2-naphthalenesulfonamide, N- (4-hydroxynaphthyl) -p-toluenesulfon Amid, N- (4-Hydroxynaphthyl) benzenesulfonamide, N- (4-hydroxynaphthyl) -1-naphthalenesulfonamide, N- (4-Hydroxynaphthyl) -2-naphthalene sulfonamide, N- (3-hydroxyphenyl) -p-toluenesulfonamide, N- (3-hydroxyphenyl) benzenesulfonamide, N- (3-hydroxyphenyl) Examples thereof include, but are not limited to, -1-naphthalenesulfonamide and derivatives of N- (3-hydroxyphenyl) -2-naphthalenesulfonamide, and these color-developing agents may be used as required. It can also be contained in combination of two or more. The proportion of the developer having three or more aromatic rings in the entire developer is preferably 50 to 100% by mass.

In order to obtain sufficient thermal responsiveness, the total amount of the color developer in the total solid content of the thermal recording layer is preferably in the range of 10 to 500% by mass with respect to the dye precursor.

The heat-sensitive recording layer in the present invention can contain a heat-soluble component having a low melting point (hereinafter, referred to as a sensitizer) that promotes a color development reaction in order to further improve its heat responsiveness. In this case, the sensitizer is preferably a compound having a melting point of 60 to 180 ° C.

Specific examples of the sensitizer include fatty acid monoamides such as palmitate monoamide and stearate monoamide, diphenylsulfone, N-hydroxymethylstearic acid amide, N-stearyl stearate amide, ethylene bisstearic acid amide, and methylene bisstearic acid. Amide, methylol stearate amide, N-stearyl urea, benzyl-2-naphthyl ether, p-toluenesulfonamide, m-terphenyl, 4-benzylbiphenyl, 2,2'-bis (4-methoxyphenoxy) diethyl ether, α, α'-diphenoxy-o-xylene, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, bis (4-methylbenzyl) oxalate ester, bis (4-chlorobenzyl) ester, dimethyl terephthalate , Dibenzyl terephthalate, benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 1,2-bis (3-methylphenoxy) ethane, 1,2-diphenoxyetane, 4-acetylacetophenone, acetoacetate anilide , And known sensitizers such as fatty acid anilides, but the present invention is not limited thereto.

Two or more of these compounds may be contained as a sensitizer. Further, in order to obtain sufficient thermal responsiveness, the total amount of the sensitizer is preferably 3 to 50% by mass in the total solid content of the heat-sensitive recording layer.

If necessary, a known preservative improving agent, surfactant, or the like may be added to the heat-sensitive recording material of the present invention.

In the present invention, the heat-sensitive recording layer can contain various pigments for the purpose of improving sticking resistance, improving whiteness, and the like. For example, siliceous soil, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, amorphous calcium silicate, colloidal silica, colloidal. Known pigments such as white inorganic pigments such as alumina, calcium sulfate, barium sulfate, zinc sulfide, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, alumina, lithopon, zeolite, and hydrohaloicite can be mentioned.

Examples of the binder of the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention include the above-mentioned urethane resin, but other than that, a known water-soluble polymer compound or water is used as long as the effects of the present invention are not impaired. It can be appropriately selected and used from the dispersible polymer compounds. Specifically, cellulose derivatives such as starches, hydroxymethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, proteins such as gelatin and casein, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, and alginic acid. Soda, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid ternary copolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, styrene / maleic anhydride Water-soluble polymer compounds such as an alkali salt of a polymer, an alkali salt of an ethylene / maleic anhydride copolymer, an alkali salt of an isobutylene / maleic anhydride copolymer, and an alkali salt of a styrene / isobutylene / maleic anhydride copolymer. , And styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene ternary copolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, Examples include, but are limited to, ethylene / vinyl acetate copolymers, polyacrylic acid esters, styrene / acrylic acid ester copolymers, and water-dispersible polymer compounds such as urethane resins having a Tg of 10 ° C. or higher. However, one type or two or more types can be used as required. The proportion of the urethane resin having a Tg of less than 10 ° C. in the entire binder is preferably 50 to 100% by mass. Further, the binder is preferably contained in the range of 30 to 60% by mass in the total solid content of the thermal recording layer.

In addition, waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, and caster wax, and lubricants such as fatty acid metal salts are applied to the heat-sensitive recording layer to improve sticking resistance, and various hard films are used to provide water resistance. The agent and the cross-linking agent can contain a dispersant such as sodium dioctyl sulfosuccinate, a surfactant, a fluorescent dye, a coloring dye, a brewing agent and the like.

Various color-developing components contained in the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention are applied and dried on a support or a coating layer as a dispersion liquid dispersed in a dispersion medium. The dispersion can be obtained by a method of dry pulverizing a compound constituting a color-developing component and dispersing it in a dispersion medium, or a method of mixing a compound constituting a color-developing component with a dispersion medium and wet pulverizing. In the present invention, the color developer and the sensitizer are used alone or together with water as a dispersion medium, and the volume average particle diameter is adjusted together with the dispersant by various wet grinders such as a sand grinder, a ball mill, an attritor, and a bead mill. It is preferable that the particles are pulverized to 0.1 to 5.0 μm and then used for preparing a heat-sensitive recording layer coating liquid. As the dye precursor, water is used as a dispersion medium separately from the color developer, and the volume average particle size is preferably 0.1 to 1 together with the dispersant by various wet pulverizers such as a sand grinder, a ball mill, an attritor, and a bead mill. It is preferable that it is used for preparing a heat-sensitive recording layer coating liquid after being pulverized to 5.0 μm into fine particles.

In the present invention, the dispersant used when dispersing the compound constituting the color-developing component contained in the heat-sensitive recording layer includes fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and carboxyl. Polyvinyl alcohols such as modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, phosphate-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, starch or derivatives thereof, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, Cellulous derivatives such as ethyl cellulose and carboxymethyl cellulose, proteins such as gelatin and casein, acid neutralized products of chitosan, sodium alginate, polyvinylpyrrolidone, diisobutylene / maleic anhydride copolymer salt, styrene / isobutylene / maleic anhydride copolymer Water-soluble polymer compounds such as salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyacrylic acid salt, polyacrylic sulfonate, dodecylbenzene Examples thereof include anionic low molecular weight surfactants such as sulfonate, dialkyl sulfosuccinate, alkylnaphthalene sulfonate, alkyldiphenyl ether disulfonate, fatty acid metal salt, and nonionic surfactants typified by acetylene glycol. , However, it is not limited to these, and one kind or two or more kinds can be contained as needed. The dispersant is preferably 0.5 to 30% by mass with respect to various color-developing components.

Further, when the color-developing component contained in the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention is pulverized, magnesium silicate, calcium silicate, magnesium carbonate, calcium carbonate, calcium sulfate, magnesium phosphate, magnesium oxide, aluminum oxide, oxidation It may be ground together with inorganic pigments such as titanium, magnesium hydroxide, aluminum hydroxide, kaolin, talcite and hydrotalcite. Further, the dispersion liquid after pulverizing various color-developing components may be heated in the range of 40 to 80 ° C.

An undercoat layer can be provided between the stretchable support and the heat-sensitive recording layer of the heat-sensitive recording material of the present invention for the purpose of improving the heat insulating property of the stretchable support. The undercoat layer can contain a binder, various inorganic and organic pigments, hollow particles and the like. In addition, examples of other components contained in the undercoat layer include known surfactants, coloring dyes, fluorescent dyes, lubricants, ultraviolet absorbers, and the like.

Pigments contained in the undercoat layer of the present invention include, for example, talc, kaolin, calcined kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide. , Inorganic pigments such as barium sulfate, zinc sulfate, amorphous silica, calcium silicate, colloidal silica, organic pigments such as melamine resin, urea-formaldehyde resin, polyethylene, polystyrene, ethylene-vinyl acetate, etc. It can be contained in combination of two or more. In order to obtain sufficient color development, the content of the pigment in the undercoat layer is preferably 20% by mass or more with respect to the total solid amount of the undercoat layer.

Further, the undercoat layer can contain various water-soluble polymer compounds or water-dispersible polymer compounds used in ordinary coating as a binder. Specific examples thereof include starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, and the like. Acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid ternary copolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene / Water-soluble polymer compounds such as alkali salts of maleic anhydride copolymers, alkali salts of isobutylene / maleic anhydride copolymers, alkali salts of styrene / isobutylene / maleic anhydride copolymers, urethane resins, styrene / butadiene Copolymer, Acrylonitrile / butadiene copolymer, Methyl acrylate / butadiene copolymer, Acrylonitrile / butadiene / styrene ternary copolymer, Polyvinyl acetate, Vinyl acetate / Acrylic acid ester copolymer, Ethylene / Vinyl acetate Examples thereof include, but are not limited to, water-dispersible polymer compounds such as polymers, polyacrylic acid esters, and styrene / acrylic acid ester copolymers. In the present invention, the binder is preferably a urethane resin having a Tg of less than 10 ° C. from the viewpoint of preventing the undercoat layer from peeling off when the support is expanded and contracted. The binder may contain one kind or two or more kinds. The ratio of the urethane resin having a Tg of less than 10 ° C. to the entire binder contained in the undercoat layer is preferably 50 to 100% by mass. The binder is preferably contained in the range of 30 to 60% by mass in the total solid content of the undercoat layer.

In the present invention, the undercoat layer is coated on a support with a coating liquid for the undercoat layer prepared by mixing and stirring a pigment and, if necessary, a binder and an auxiliary agent using water or the like as a medium, and drying the undercoat layer. It is formed.

In the present invention, when various components contained in the undercoat layer are mixed and stirred using water or the like as a medium, a dispersant can be used to improve the dispersibility. Dispersants used include polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and modified polyvinyl alcohol, starch or derivatives thereof, and cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose, and carboxymethyl cellulose. , Gelatin, proteins such as casein, acid neutralized products of chitosan, sodium alginate, polyvinylpyrrolidone, diisobutylene / maleic anhydride copolymer salt, styrene / isobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride Water-soluble polymer compounds such as polymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyacrylic acid salt, polyacrylic sulfonate, dodecylbenzene sulfonate, dialkyl sulfosuccinate , Alkylnaphthalene sulfonate, alkyldiphenyl ether disulfonate, anionic low molecular weight surfactants such as fatty acid metal salts, nonionic surfactants typified by acetylene glycol, sodium hexametaphosphate and the like, but are limited thereto. However, one type or two or more types can be used as required. The dispersant is preferably 0.1 to 30% by mass with respect to various components.

In the present invention, the heat-sensitive recording layer is provided with a protective layer for the purpose of improving sticking resistance, preventing scratches, improving water resistance, improving plasticizer resistance and chemical resistance of heat-sensitive color-developed images, and the like. Can be done. The protective layer may contain various adhesives, inorganic pigments, lubricants, various curing agents, various cross-linking agents, ultraviolet absorbers and the like, and a single layer or two or more layers may be laminated.

Examples of the pigment contained in the protective layer of the present invention include siliceous soil, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium dioxide, zinc oxide, silicon oxide, and amorphous. White inorganic substances such as silica, amorphous calcium silicate, colloidal silica, colloidal alumina, calcium sulfate, barium sulfate, zinc sulfide, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, alumina, lithopon, zeolite, and hydrohaloidite. Known pigments such as pigments can be mentioned, but the present invention is not limited thereto. The pigment may contain one kind or two or more kinds.

In addition, the protective layer can contain various water-soluble polymer compounds or water-dispersible polymer compounds used in ordinary coating as a binder. Specific examples thereof include starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, and acrylamide. / Acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid ternary copolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene / anhydrous Water-soluble polymer compounds such as alkali salts of maleic acid copolymers, alkali salts of isobutylene / maleic anhydride copolymers, alkali salts of styrene / isobutylene / maleic anhydride copolymers, urethane resins, and styrene / butadiene Polymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene ternary copolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer Examples thereof include, but are not limited to, water-dispersible polymer compounds such as coalescing, polyacrylic acid ester, and styrene / acrylic acid ester copolymer. In the present invention, the binder is preferably a urethane resin having a Tg of less than 10 ° C. from the viewpoint of preventing the protective layer from peeling off when the support is expanded and contracted. The binder may contain one kind or two or more kinds. The ratio of the urethane resin having a Tg of less than 10 ° C. to the entire binder contained in the protective layer is preferably 50 to 100% by mass. The binder is preferably contained in the range of 20 to 90% by mass in the total solid content of the protective layer.

Further, the protective layer may contain waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide and caster wax, or fatty acid metal salts in order to improve sticking resistance.

In the present invention, the protective layer is formed by applying a coating liquid for a protective layer prepared by mixing and stirring a pigment, a binder, and an auxiliary agent together using water or the like as a medium on the heat-sensitive recording layer and drying it. ..

In the present invention, when various components contained in the protective layer are mixed and stirred using water or the like as a medium, a dispersant can be used to improve the dispersibility. Dispersants used include polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and modified polyvinyl alcohol, starch or derivatives thereof, and cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose, and carboxymethyl cellulose. , Gelatin, proteins such as casein, acid neutralized products of chitosan, sodium alginate, polyvinylpyrrolidone, diisobutylene / maleic anhydride copolymer salt, styrene / isobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride Water-soluble polymer compounds such as polymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyacrylic acid salt, polyacrylic sulfonate, dodecylbenzene sulfonate, dialkyl sulfosuccinate , Alkylnaphthalene sulfonate, alkyldiphenyl ether disulfonate, anionic low molecular weight surfactants such as fatty acid metal salts, nonionic surfactants typified by acetylene glycol, sodium hexametaphosphate and the like, but are limited thereto. However, one type or two or more types can be used as required. The dispersant is preferably 0.1 to 30% by mass with respect to various components.

In the present invention, the amount of solid content coated on the heat-sensitive recording layer is preferably ² to 15 g / m ² . If it is less than 2 g / m ² , the color development property may be deteriorated, and if it is more than 15 g / m ² , the improvement of various performances of the heat-sensitive recording layer reaches saturation, and the production efficiency at the time of coating the heat-sensitive recording layer is lowered. May be done. As the coating amount of the undercoat layer, the solid content coating amount after drying is preferably 4 to ²⁰ g / m ² . If it is less than 4 g / m ^2, various performances of the undercoat layer may not be exhibited, and if it is more than 20 g / m ² , the improvement of various performances of the undercoat layer reaches saturation, and when the undercoat layer is applied. Production efficiency may decrease. The amount of coating of the protective layer is preferably 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , various performances of the protective layer may not be exhibited, and if it is more than 5 g / m ² , the loss of heat energy reaching the heat sensitive recording layer from the thermal head increases and the color development property deteriorates. May be invited.

In the present invention, a backcoat layer may be provided on the surface opposite to the surface having the heat-sensitive recording layer for the purpose of curl prevention, antistatic, etc., and further adhesive processing or the like may be performed. Further, a layer containing a material capable of recording information electrically, magnetically, or optically may be provided on the surface provided with the heat-sensitive recording layer or the surface on the opposite side, an inkjet recording layer, or the like. Further, in order to perform printing by laser light, any layer and paper support in the heat-sensitive recording material can contain a photothermal conversion material.

The method for forming each layer in the present invention is not particularly limited and can be formed by using a well-known technique. For example, an air knife coater, various blade coaters, various bar coaters, various curtain coaters, and various roll coaters. And various printing methods such as planographic printing, letterpress, intaglio, flexography, gravure, and screen can be used. Further, in order to improve the surface smoothness, various known techniques in the production of thermal recording materials can be used, such as the use of devices such as a machine calendar, a super calendar, a gloss calendar, and brushing.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified,% and parts are all based on mass. The amount of coating is the amount of absolute dry coating.

Example 1

(1) Preparation of Dye Precursor Dispersion Solution The following formulations were mixed and wet-ground with a bead mill until the volume average particle size became 0.7 μm to obtain a dye precursor dispersion solution.
3-Di-n-Butylamino-6-Methyl-7-anilinofluorane 27 parts 10% sulfonic acid-modified polyvinyl alcohol aqueous solution 27 parts Water 46 parts

(2) Preparation of Color Developer Dispersion Solution The following formulations were mixed and wet-pulverized with a bead mill until the volume average particle size became 0.7 μm to obtain a color developer dispersion liquid.
4,4'-Bis [(4-Methyl-3-phenoxycarbonylaminophenyl) ureido] Diphenyl sulfone (UU, manufactured by Chemipro Kasei Co., Ltd.) 110 parts 10% sulfonic acid-modified polyvinyl alcohol aqueous solution 110 parts Water 180 parts

(3) Preparation of heat-sensitive recording layer coating liquid The following formulations were mixed and sufficiently stirred to obtain a heat-sensitive recording layer coating liquid.
Dye precursor dispersion 100 parts Color developer dispersion 400 parts 10% polyester urethane resin water dispersion 1010 parts (manufactured by DIC Corporation, Hydran AP-70 (Tg-4 ° C) diluted with water)
75% dioctyl sodium sulfosuccinate solution 3 parts (Nikko Chemicals Co., Ltd., Nikkor® OTP-75)
7 parts of 12% polycarboxylic acid sodium salt solution (manufactured by San Nopco Co., Ltd., SN thickener 929-S)

(4) Preparation of heat-sensitive recording material On one surface of a urethane film (manufactured by Seadam Co., Ltd., Higres DUS202, thickness 300 μm, tensile elongation 460% or more, recovery rate at 200% elongation 95%), the above (3) The heat-sensitive recording layer coating liquid prepared in the above was coated and dried so that the solid content coating amount was 6.0 g / m ^2, and the heat-sensitive recording material of Example 1 was prepared.

Example 2
In the preparation of (3) heat-sensitive recording layer coating liquid of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C) diluted with water) was used. Heat-sensitive recording of Example 2 in the same manner as in Example 1 except that it was changed to a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-201 (Tg 7 ° C.) diluted with water). The material was made.

Example 3
In the preparation of (2) color developer dispersion liquid of Example 2, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone (manufactured by Chemipro Kasei Co., Ltd., UU) was used. , 3- (3-tosylureido) phenyl-p-toluenesulfonate (PERGAFAST201, manufactured by BASF) was used to prepare the heat-sensitive recording material of Example 3 in the same manner as in Example 2.

Example 4
In the preparation of the (2) color developer dispersion liquid of Example 2, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone (manufactured by Chemipro Kasei Co., Ltd., UU) was used. , N- [2- (3-Phenylureido) phenyl] benzenesulfonamide was used in the same manner as in Example 2 to prepare the heat-sensitive recording material of Example 4.

Example 5
In the preparation of the (2) color developer dispersion liquid of Example 2, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone (manufactured by Chemipro Kasei Co., Ltd., UU) was used. , 2,4-Bis (phenylsulfonyl) phenol was used in the same manner as in Example 2 except that the heat-sensitive recording material of Example 5 was prepared.

Comparative Example 1
In the preparation of (3) heat-sensitive recording layer coating liquid of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C) diluted with water) was used. Thermal recording of Comparative Example 1 in the same manner as in Example 1 except that it was changed to a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran APX-101H (Tg17 ° C.) diluted with water). The material was made.

Comparative Example 2
In the preparation of (3) heat-sensitive recording layer coating liquid of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C) diluted with water) was used. Thermal recording of Comparative Example 2 in the same manner as in Example 1 except that it was changed to a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-20 (Tg 27 ° C.) diluted with water). The material was made.

Comparative Example 3
In the preparation of (3) heat-sensitive recording layer coating liquid of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C) diluted with water) was used. Heat-sensitive recording of Comparative Example 3 in the same manner as in Example 1 except that it was changed to a 10% polyester resin aqueous dispersion (manufactured by Takamatsu Oil & Fat Co., Ltd., pesresin A-510 (Tg35 ° C.) diluted with water). The material was made.

Comparative Example 4
In the preparation of the (3) heat-sensitive recording layer coating solution of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C.) diluted with water) was used. Same as in Example 1 except that the solution was changed to a 10% aqueous solution of ethylene-sodium acrylate salt (manufactured by Sumitomo Seika Co., Ltd., diluted with water from Zyxen® NC (Tg-50 ° C)). , The heat-sensitive recording material of Comparative Example 4 was prepared.

Comparative Example 5
In the preparation of (3) heat-sensitive recording layer coating liquid of Example 1, a 10% polyester urethane resin aqueous dispersion (manufactured by DIC Co., Ltd., Hydran AP-70 (Tg-4 ° C) diluted with water) was used. In the same manner as in Example 1 except that the solution was changed to a 10% styrene / butadiene copolymer aqueous dispersion (manufactured by JSR Co., Ltd., PCL / SB latex 0696 (Tg-12 ° C.) diluted with water). The heat-sensitive recording material of Comparative Example 5 was prepared.

Comparative Example 6
In the preparation of (4) heat-sensitive recording material of Example 1, a urethane film (manufactured by Seadam Co., Ltd., Higres DUS202, thickness 300 μm, tensile elongation 460% or more, recovery rate at 200% elongation 95%) was used as a polyethylene terephthalate film. Comparative Example 6 in the same manner as in Example 1 except that the film was changed to (Mitsubishi Chemical Corporation, Diafoil (registered trademark) T600E50, thickness 50 μm, tensile elongation 220%, recovery rate at 200% elongation 40%). The heat-sensitive recording material of was prepared.

Comparative Example 7
In the preparation of the (2) developer dispersion of Example 1, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone (manufactured by Chemipro Kasei Co., Ltd., UU) was used. , 2,4-Dihydroxydiphenylsulfone was changed to, and the heat-sensitive recording material of Comparative Example 7 was prepared in the same manner as in Example 1.

Comparative Example 8
In the preparation of the (2) developer dispersion of Example 1, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone (manufactured by Chemipro Kasei Co., Ltd., UU) was used. , 4-Hydroxyphenyl-4-isopropoxyphenyl sulfone was used in the same manner as in Example 1 except that the heat-sensitive recording material of Comparative Example 8 was prepared.

The thermal recording materials of Examples 1 to 5 and Comparative Examples 1 to 8 obtained as described above were subjected to the following evaluation. The results of each are shown in Table 1.

[Elasticity]
For each of the prepared heat-sensitive recording materials, the tensile elongation (%) and the recovery rate at 200% elongation (%) were measured by the above method in an environment of 23 ° C. and 65% RH, and the following criteria were used. Evaluated according to.
◯: Tensile elongation 200% or more and 200% elongation recovery rate 90% or more ×: Tensile elongation less than 200% or 200% elongation recovery rate less than 90%

[Color development]
For each of the produced heat-sensitive recording materials, a sample was subjected to a thermal tilt tester (HG-100-2, manufactured by Toyo Seiki Seisakusho Co., Ltd.) under an environment of 23 ° C. and 65% RH, and the printing temperature was 150 ° C. and pressure was applied. Printing was performed under the conditions of 50 kPa and a printing time of 5 seconds, and the optical density of the printed portion was measured with a densitometer (RD19 manufactured by GretagMacbeth) (black mode) and evaluated according to the following criteria.
⊚: Color density of the printed part is 1.0 or more ○: Color density of the printed part is 0.5 or more and less than 1.0 ×: Color density of the printed part is less than 0.5

[Water resistant coating layer strength]
For each of the prepared thermal recording materials, the sample was immersed in water at 23 ° C. for 1 minute, the sample was taken out, and the sample while still wet with water was rubbed with a finger and evaluated according to the following criteria.
◯: The coating layer does not peel off even if the number of scrapes is 30 or more.
X: The coating layer is peeled off when the number of times of rubbing is less than 30 times.

[Coating layer strength during expansion and contraction]
Each of the produced heat-sensitive recording materials was cut into strips having a length of 150 mm and a width of 10 mm in the length direction, and under an environment of 23 ° C. and 65% RH, a single column type material testing machine STA- made by Orientec Co., Ltd. Using 1150, the initial tensile chuck distance was 50 mm, the elongation was 200% (100 mm) at a speed of 200 mm / min, and after 10 seconds, the elongation strain was released at a speed of 450 mm / min, and then the evaluation was performed according to the following criteria.
◯: The peeling of the coating layer cannot be confirmed even if the sample is rubbed. ×: The peeling of the coating layer can be confirmed by rubbing the sample.

As is clear from the description in Table 1, it can be seen that the present invention provides a heat-sensitive recording material having excellent elasticity, color development, water resistance coating layer strength, and coating layer strength during expansion and contraction.

Claims (1)

It is characterized by having a heat-sensitive recording layer on an elastic support, and the heat-sensitive recording layer contains at least a color developer having three or more aromatic rings in the molecule and a urethane resin having a glass transition temperature of less than 10 ° C. Thermal recording material.