JPH05318937A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance various characteristics, raw preservability and the preservability of a recording image by using at least one of a salicylic acid derivative represented by a specific chemical formula and a phenol derivative represented by a specific chemical formula as the developer in the thermal recording layer provided on the upper surface of a support. CONSTITUTION:A thermal recording material is constituted by successively providing a thermal recording layer containing a colorless or light-colored basic dye and a developer developing a color upon the contact with the basic dye, an intermediate layer containing a water-soluble or water-dispersible resin and an overcoat layer containing an ionizing radiation curable resin on the upper surface of a support. In this case, a plurality of specific components are added to the thermal recording layer as the developer. That is, as one component, at least one kind of a salicylic acid derivative represented by chemical formula I or a polyvalent metal salt thereof is used and, as the other component, at least one kind of a phenol derivative represented by chemical formula II is used. By this constitution, the preservability of a recording image, especially, the preservability of medium contrast is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording material having a high density, high sensitivity, excellent gradation recording property, and excellent raw storage property and recorded image storage property. ..

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to bring both color-forming substances into contact with each other by heat to obtain a recorded image is often used. Are known. Since such a thermosensitive recording medium is relatively inexpensive, the recording device is compact, and its maintenance is relatively easy, it can be used not only as a recording medium for facsimiles and various computers, but also for a wide range of POS (Point of Sales) labels and the like. Used in the field.

However, thermosensitive recording media utilizing the above-mentioned color reaction generally have poor chemical resistance. For example, when human sebum, a plasticizer, or an organic solvent comes into contact with the recording layer, the recording density is lowered, or background fog is caused. There is a drawback that it causes unnecessary color development called as. In order to improve such a defect, an intermediate layer containing a water-based resin as a main component is provided on the thermosensitive recording layer, and an overcoat layer containing a resin curable by an electron beam is further provided on the intermediate layer to form a recording layer. JP-A-62-279980 discloses that a heat-sensitive recording material having improved image storability, wide surface characteristics and excellent recording characteristics can be obtained.

On the other hand, in recent years, heat-sensitive video printers which provide high-quality images of photographic tone have been used, and a heat-sensitive recording material excellent in recording density and gradation recording property is required. Therefore, a plastic film is used as a support. Development of thermal recording materials using synthetic paper and paper is underway. Even in such a thermal recording material for a video printer, the storability of the recorded image and the background portion is required, and therefore, the thermal recording layer, on the support made of plastic film or synthetic paper,
Japanese Patent Application Laid-Open No. 63-99984 proposes a method of sequentially providing an intermediate layer containing a water-based resin as a main component and an overcoat layer containing a resin curable by an electron beam.

However, even in the above-described thermal recording material, the halftone recorded image (the density of the recorded image is in the range of 0.2 to 1.0 measured by a Macbeth densitometer) is discolored at high temperature or high humidity. But. Therefore, in order to improve these drawbacks, we propose to use a specific salicylic acid derivative or its polyvalent metal salt as a color developing agent.
Proposed in Japanese Patent No. 2656. However, with the recent increase in recording speed, it has been found that the recording sensitivity and recording density are still insufficient, and there is a demand for improvement thereof.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems, is excellent in recording density, recording sensitivity, and gradation recording property, has less background fog, and has excellent storage stability of recorded images, especially in halftone. It is an object of the present invention to provide a thermosensitive recording medium having excellent storage stability.

[0007]

The present inventors have found that a heat-sensitive recording layer containing a colorless or light-colored basic dye and a coloring agent capable of coloring on contact with the support on a support, a water-soluble layer. In a thermosensitive recording medium in which an intermediate layer containing a resin or a water-dispersible resin and an overcoat layer containing an ionizing radiation effect type resin are sequentially provided, salicylic acid represented by [Chemical Formula 1] is used as a coloring agent in the thermosensitive recording layer. It has been found that the above object can be achieved by incorporating at least one derivative or a polyvalent metal salt thereof and at least one phenol derivative represented by [Chemical Formula 2], and completed the present invention.

[0008]

[Chemical 1]

[Wherein, X is a C ₁ -C ₄ alkyl group, C
_{1 to} C ₄ alkoxyl group or a halogen atom,
A represents a C _{2 to} C ₆ alkylene group, and l is 0 or 1
Indicates an integer of ˜5. ]

[0010]

[Chemical 2]

[Wherein, Y and Z each represent a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group or a halogen atom, and m, n, o and p are 0 or 1 to 5 respectively.
Indicates an integer. However, m and n are not 0 at the same time, and m +
o ≦ 5 and n + p ≦ 5. ]

[0012]

The heat-sensitive recording material of the present invention comprises at least one of the specific salicylic acid derivative represented by the general formula [Chemical formula 1] or a polyvalent metal salt thereof as a colorant, and [Chemical formula 2].
By using at least one of the phenol derivatives represented by, the color development and gradation recording properties are excellent, and the recorded image, especially the halftone recorded image, is extremely stable, and is also suitable for raw storage under high temperature environment. An excellent thermal recording material can be obtained.

Specific examples of the salicylic acid derivative represented by the general formula [Formula 1] include the following. 4-
(2-p-Tolylsulfonylethoxy) salicylic acid, 4
-(3-p-Tolylsulfonylpropyloxy) salicylic acid, 4- (3-o-tolylsulfonylpropyloxy) salicylic acid, 4- (3-m-tolylsulfonylpropyloxy) salicylic acid, 4- (4-p-tolylsulfonyl) Butyloxy) salicylic acid, 4- (6-p-tolylsulfonylhexyloxy) salicylic acid, 4- (3-p
-Ethylphenylsulfonylpropyloxy) salicylic acid, 4- (3-phenylsulfonylpropyloxy) salicylic acid, 4- (4-phenylsulfonylbutyloxy) salicylic acid, 4- (3-p-chlorophenylsulfonylpropyloxy) salicylic acid, 4- ( 4-p-chlorophenylsulfonylbutyloxy) salicylic acid, 4-
(3-o-chlorophenylsulfonylpropyloxy)
Salicylic acid, 4- (3-p-bromophenylsulfonylpropyloxy) salicylic acid, 4- (3-p-methoxyphenylsulfonylpropyloxy) salicylic acid, 4-
(4-p-methoxyphenylsulfonylbutyloxy)
Salicylic acid, 4- (3-p-isopropyloxyphenylsulfonylpropyloxy) salicylic acid, 4- (4-
p-isopropyloxyphenylsulfonylbutyloxy) salicylic acid, 5- (3-p-tolylsulfonylpropyloxy) salicylic acid, 5- (3-phenylsulfonylpropyloxy) salicylic acid, 5- (3-p-methoxyphenylsulfonylpropyloxy) Salicylic acid, 5
-(3-p-Chlorophenylsulfonylpropyloxy) salicylic acid, 4- [3- (3,5-dimethylphenylsulfonyl) propyloxy] salicylic acid, 4- [3
-(3,4,5-trimethylphenylsulfonyl) propyloxy] salicylic acid, 4- [3- (3,5-dichlorophenylsulfonyl) propyloxy] salicylic acid,
4- [3- (3,4,5-trichlorophenylsulfonyl) propyloxy] salicylic acid, 4- [2- (3-chloro-4-methylphenylsulfonyl) ethoxy) salicylic acid and the like.

The polyvalent metal forming a salt with the salicylic acid derivative is preferably a divalent, trivalent or tetravalent metal, particularly zinc, calcium, aluminum, magnesium, tin or iron, particularly zinc. .. The salicylic acid derivative and / or its polyvalent metal salt as described above are not limited to these, and two or more kinds can be used in combination. The amount used is not particularly limited, but is generally 50 to 700 parts by weight, preferably 100 to 5 parts by weight with respect to 100 parts by weight of a colorless or light-colored basic dye.
It is adjusted in the range of about 00 parts by weight.

In the present invention, the phenol derivative represented by [Chemical Formula 2] used in combination with the above specific salicylic acid derivative or a polyvalent metal salt thereof is exemplified by the following. 3-hydroxybenzophenone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4,4'-dihydroxybenzophenone, 3,3 '
-Dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 2,2 ', 4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2', 4,4'-tetrohydroxybenzophenone, 2- Methyl-4'-hydroxybenzophenone, 3-methyl-4'-hydroxybenzophenone, 4
-Methyl-4'-hydroxybenzophenone, 4-isopropyl-4'-hydroxybenzophenone, 4-methoxy-4'-hydroxybenzophenone, 4-ethoxy-4'-hydroxybenzophenone, 4-isopropoxy-4'-hydroxybenzophenone, 4-tert-butoxy-4'-hydroxybenzophenone, 2-chloro-
4'-hydroxybenzophenone, 3-chloro-4'-
Hydroxybenzophenone, 4-chloro-4'-hydroxybenzophenone, 2,4-dimethyl-4'-hydroxybenzophenone, 2,4-dichloro-4'-hydroxybenzophenone, 2,3,4-trichloro-4'-
Hydroxybenzophenone, 2-methyl-4-chloro-
4'-hydroxybenzophenone, 2-methyl-4,
4'-dihydroxybenzophenone and the like. Of course, it is not limited to these phenol derivatives, and two or more kinds can be used in combination. Of these, 4,4'-dihydroxybenzophenone is particularly preferably used because it causes less background fog. The amount used is not particularly limited, but is generally 20 to 300 parts by weight, preferably 50 to 200 parts by weight with respect to 100 parts by weight of the salicylic acid derivative represented by [Chemical formula 1] or its polyvalent metal salt. It is preferable to adjust within the range of parts.

When a metal compound is contained in the heat-sensitive recording layer together with these color formers, the storage characteristics of the heat-sensitive recording material can be further improved. The metal compound referred to here is an oxide of a divalent, trivalent or tetravalent metal, for example, a metal selected from zinc, magnesium, barium, calcium, aluminum, tin, titanium, nickel, cobalt, manganese, iron and the like. Examples thereof include hydroxides, sulfides, halides, carbonates, phosphates, silicates, sulfates, nitrates, and halogen complex salts, and of these, zinc compounds are particularly preferable. Specific examples of the metal compound include zinc oxide, zinc hydroxide, zinc aluminate, zinc sulfide, zinc carbonate, zinc phosphate, zinc silicate, aluminum oxide, magnesium oxide, titanium oxide, aluminum hydroxide, aluminum silicate. , Aluminum phosphate,
Examples include magnesium aluminate, magnesium hydroxide, magnesium carbonate, magnesium phosphate and the like. Of course, it is not limited to these metal compounds, and it is also possible to use two or more kinds in combination. The amount of these metal compounds used is in the range of 1 to 500 parts by weight, preferably 5 to 300 parts by weight, per 100 parts by weight of the compound of the general formula [Chemical Formula 1] or its polyvalent metal salt and [Chemical Formula 2]. Adjusted.

Various known compounds can be used as the colorless or light-colored basic dye which constitutes the thermosensitive recording medium of the present invention, and the following are exemplified. 3,3-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3-
(4-Diethylamino-2-methylphenyl) -6-
(Dimethylamino) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-3)
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
6-Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6
-Dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3-
(4-Diethylamino-2-methylphenyl) -3-
(1-octyl-2-methylidol-3-yl) -4
-Azaphthalide, 3,3-bis (4-diethylamino-
2-ethoxyphenyl) -4-azaphthalide, 3,3-
Bis (4-diethylamino-2-methoxyphenyl)
-4-Azaphthalide and other triarylmethane dyes,
4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leuco auramine, N
-Diphenylmethane dye such as 2,4,5-trichlorophenylleuco auramine, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-Tetrabromophthalide, 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 and other divinylphthalide dyes, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and other thiazine dyes, 3-methyl-spiro-dinaphthopyran , 3-ethyl-spiro-dinaphthopyran,
3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6 '
-Methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran and other spiro dyes, rhodamine-B
-Lactam dyes such as anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino -7-Methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3
-Diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-7-N -Acetyl-
N-methylaminofluorane, 3-diethylamino-7
-N-methylaminofluorane, 3-diethylamino-
7-dibenzylaminofluorane, 3-diethylamino-7-N-methyl-N-benzylaminofluorane, 3
-Diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 4-benzylamino-8-diethylamino-benzo [a] fluorane, 3- [4- (4
-Dimethylaminoanilino) anilino] -7-chloro-
6-methylfluorane, 8- [4- (4-dimethylaminoanilino) anilino] -benzo [a] fluorane, 3
-(N-ethyl-p-toluidino) -6-methyl-7-
Phenylaminofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-dimethylamino- 6-methyl-7-phenylaminofluorane, 3-di-n-butylamino-6-methyl-7-phenylaminofluorane,
3-di-n-pentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-
Carbomethoxyphenylamino) fluorane, 3- (N
-Ethyl-N-isoamylamino) -6-methyl-7-
Phenylaminofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6- Methyl-
7-phenylaminofluorane, 3-diethylamino-
6-methyl-7-xylidinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di-n-butylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl) -N-n-
Hexylamino) -7- (o-chlorophenylamino)
Fluorane, 3- (N-ethyl-N-isoamylamino) -7- (o-chlorophenylamino) fluorane,
3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-phenylaminofluorane, 3
-(N-methyl-N-n-propylamino) -6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-isobutylamino) -6-methyl-7-phenylaminofluorane, 3 -(N-methyl-Nn-hexylamino) -6-methyl-7-phenylaminofluorane, 3- [N- (3-ethoxypropyl) -N-methylamino] -6-methyl-7-phenyl Aminofluorane, 3- [N-ethyl-N- (3-ethoxypropyl)
Amino] -6-methyl-7-phenylaminofluorane, 3-diethylamino-7- [m- (trifluoromethyl) phenylamino] fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane,
3-di-n-butylamino-7- (o-fluorophenylamino) fluorane, 3-diethylamino-6-chloro-7-phenylaminofluorane, 3- (N-ethyl-Nn-hexylamino)- 6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-cyclopentylamino) -6-methyl-7-phenylaminofluorane, 2,2-bis {4- [6 '-(N- Fluorane dyes such as cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2'-ylamino] phenyl} propane, 3,6-bis (dimethylamino) fluorene-9- Spiro-3'-
(6'-Dimethylamino) phthalide, 3-diethylamino-6- (N-allyl-N-methylaminofluorene-
9-spiro-3 '-(6'-dimethylamino) phthalide, 3,6-bis (dimethylamino) -spiro [fluorene-9,6'-6'H-chromeno (4,3-b) indole], 3,6-Bis (dimethylamino) -3'-methyl-spiro [fluorene-9,6'-6'H-chromeno (4,3-b) indole], 3,6-bis (diethylamino) -3 ' -Methyl-spiro [fluorene-9,
6'-6'H-chromeno (4,3-b) indole] and other fluorene dyes. Of course, the dyes are not limited to these dyes, and two or more dyes may be used in combination.

Among the basic dyes as described above, the fluoran dye represented by the following [Chemical formula 3] is used in combination with the specific color-forming agent of the present invention to obtain a recorded image having a deep black color tone. Is more preferable because

[0019]

[Chemical 3]

[Wherein R ₁ and R ₂ are each C _{1 to} C ₆
Is an alkyl group, a C ₃ -C ₆ alkoxyalkyl group, a cyclopentyl group, a cyclohexyl group, a tetrahydrofurfuryl group, or a p-tolyl group. Note that R ₁ and R
₂ may form a pyrrolidine ring or a piperidine ring with the adjacent nitrogen atom. X ₁ represents a chlorine atom, a fluorine atom, or a trifluoromethyl group, and p represents 1 or 2. ]

Further, various known heat-fusible substances can be used in combination depending on the purpose. Specific examples of the heat-fusible substance include caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, and N-methylstearic acid amide. , Stearic acid anilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyllauric acid amide, N-octadecylacetamide, N-oleinacetamide, N-oleylbenzamide, N-stearyl. Cyclohexylamide,
Polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis (3-
Methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1-phenoxy-2- (4-
Methoxyphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, p
-Benzyloxybenzoic acid benzyl ester, p-benzylbiphenyl, 1,5-bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p -Tolyl ether, benzyl-p-methylthiophenyl ether, 2,2'-methylenebis (4-methyl-6-tert.
-Butylphenol), 2,2'-methylenebis (4-
Ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) ) Butane, 1,1,3-
Examples are compounds such as tris (5-cyclohexyl-4-hydroxy-2-methylphenyl) butane. The amount of the heat-fusible substance used is not particularly limited, but generally 50 to 70 per 100 parts by weight of the basic dye.
It is desirable to adjust the amount in the range of 0 parts by weight, preferably 100 to 500 parts by weight.

The coating liquid containing these components is generally prepared by using water as a dispersion medium and stirring, for example, with a ball mill, attritor, vertical or horizontal sand mill, colloid mill or the like.
It is prepared by dispersing a basic dye, a coloring agent, a heat-fusible substance and the like together or separately by a pulverizer. In the coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt as a binder, A styrene / butadiene copolymer emulsion or the like is added in an amount of 10 to 40% by weight, preferably 15 to 30% by weight, based on the total solid content.

Various auxiliaries can be added to the coating solution. For example, disodium dioctylsulfosuccinate sodium salt, dodecylbenzenesulfonic acid sodium salt, lauryl alcohol sulfate / sodium salt, fatty acid metal salt, and the like. Examples include benzophenone-based, triazole-based, cyanoacrylate-based, hydroxybenzoate-based ultraviolet absorbers, other defoaming agents, fluorescent dyes, and coloring dyes.

Further, dispersions and emulsions of stearic acid ester wax, polyethylene wax, carnauba wax, microcrystalline wax, carboxy-modified paraffin wax, zinc stearate, calcium stearate, kaolin, clay, talc, calcium carbonate, magnesium carbonate, Calcined clay, titanium oxide, diatomaceous earth, finely particulate anhydrous silica, inorganic pigments such as activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler,
Organic pigments such as raw starch granules can also be added.

In the heat-sensitive recording material of the present invention, the support is
Examples thereof include paper, plastic film, synthetic paper, and non-woven fabric sheet. Among them, in the case of plastic film or synthetic paper, a thermosensitive recording medium excellent in gradation recording property can be obtained. It should be noted that a plastic film or a synthetic paper, which is attached to a coated paper or a high-quality paper with an adhesive, and a sheet obtained by laminating a plastic on the paper are also included in the plastic film or the synthetic paper.

Examples of the plastic film include films of polyethylene, polypropylene, polystyrene, nylon, polyester, polyvinyl chloride and the like, and examples of the synthetic paper include synthetic paper manufactured by a film method or a fiber method. It The film method includes an internal paper-forming method in which a synthetic resin, a filler, and an additive are melt-kneaded and then extruded to form a film, a surface coating method in which a pigment coating layer is provided, a surface treatment method, and the like. Examples of synthetic paper include synthetic pulp paper and spunbond paper.
Among these supports, the plastic film and the film method synthetic paper are most preferably used because they give more excellent recording characteristics. It is also possible to provide an undercoat layer between the support and the recording layer.

The coating method of the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally well-known technique. For example, bar coating, air knife coating, rod blade coating, pure blade coating, short dwell coating, etc. Is formed by a method of applying and drying the coating liquid. When a plastic film is used as the support, the coating efficiency can be increased by subjecting the surface to a treatment such as corona discharge or electron beam irradiation. The coating amount of the coating liquid is also not particularly limited, but is usually ² to 12 g / m ² in dry weight, preferably 3 to
The range is about 10 g / m ² .

In the heat-sensitive recording material of the present invention, an intermediate layer is first provided on the heat-sensitive recording layer thus obtained.
Examples of the water-soluble resin or water-dispersible resin used in the intermediate layer include the following substances. Completely or partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol having acetoacetyl group introduced by reacting polyvinyl alcohol with diketene, polyvinyl alcohol and fumaric acid, phthalic anhydride, trimellitic anhydride, itaconic anhydride Or a reaction product of a polyvalent carboxylic acid such as these with an esterified product of these reaction products, and further vinyl acetate and an ethylenically unsaturated carboxylic acid such as maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid or methacrylic acid. Carboxyl group-modified polyvinyl alcohol obtained as a saponified product of a copolymer of sulfonic acid-modified polyvinyl alcohol obtained as a saponified product of a copolymer of vinyl acetate and an olefin sulfonic acid such as ethylene sulfonic acid and allyl sulfonic acid, or a salt thereof. , Olefin-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acid with an olefin such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadodecene, vinyl acetate and acrylonitrile, methacrylonitrile, etc. Nitrile-modified polyvinyl alcohol obtained as a saponification product of a copolymer with nitriles, amide-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate with amides such as acrylamide and methacrylamide, vinyl acetate and N
-Pyrrolidone-modified polyvinyl alcohol obtained by saponifying a copolymer with vinylpyrrolidone, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose,
Cellulose derivatives such as carboxymethyl cellulose, casein, gum arabic, oxidized starch, etherified starch, starches such as dialdehyde starch, esterified starch, styrene-butadiene copolymer emulsion, vinyl acetate-vinyl chloride-ethylene copolymer emulsion , Methacrylate-butadiene copolymer emulsion and the like. Among these water-soluble resins or water-dispersible resins, various modified polyvinyl alcohols, cellulose derivatives and casein are preferable, and acetoacetyl group-modified polyvinyl alcohols and carboxy-modified polyvinyl alcohols are particularly preferable.

A pigment may be added to the intermediate layer in order to enhance suitability for coating. Specific examples of the pigment include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate,
Examples thereof include inorganic pigments such as zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea formalin resin filler, and organic pigments such as raw starch. The amount used is generally 10
5 to 500 parts by weight, preferably 80 to 0 parts by weight
It is mixed in the range of about 350 parts by weight.

Further, when the intermediate layer is formed, if necessary, glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, ammonium chloride, etc. are hardened in the coating solution. Lubricants, lubricants such as zinc stearate, calcium stearate, stearic acid amide, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate, alginate, fatty acid salt It is also possible to appropriately add various kinds of auxiliary agents such as a surface active agent such as benzophenone, an ultraviolet absorber such as benzophenone and a triazole, an antifoaming agent, a fluorescent dye and a coloring dye.

The coating liquid for forming the intermediate layer is generally prepared as an aqueous coating liquid, and if necessary, sufficiently mixed and dispersed by a mixing / stirring machine such as a mixer, attritor, ball mill, roll mill, etc. It is also possible to apply the composition on the heat-sensitive recording layer with the application apparatus described above, and after the application, cure and dry by irradiating with ultraviolet rays or electron beams. When a curing agent is used in combination, the curing agent can be applied not only in the coating liquid that forms the intermediate layer, but also separately from the coating liquid that forms the intermediate layer. There is an advantage that a strong curing agent can be selected without having to worry about life.

The coating amount of the coating liquid for forming the intermediate layer is not particularly limited, but if it is less than 0.1 g / m ² , the desired effect of the present invention cannot be sufficiently obtained, and 20
If it exceeds g / m ² , the recording sensitivity of the thermosensitive recording medium may be remarkably reduced, so that the dry weight is generally 0.1 to 20.
g / m ^2, it is preferably adjusted in the range of about 0.5 to 10 g / m ^2.

If desired, a similar coat layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Further, various known techniques in the field of heat-sensitive recording material production can be added as necessary, such as providing an undercoat layer on the support or subjecting the back surface of the recording material to an adhesive treatment to form an adhesive label.

An overcoat layer containing an ionizing radiation-curable resin is provided on the intermediate layer thus formed. By further increasing the smoothness of the surface of the intermediate layer, a recording material having a high recording density and gloss can be obtained. Therefore, for example, a smoothing process is performed with a super calender or the like. Generally, when the support is a film or synthetic paper, the smoothness is adjusted to be higher than that when the support is a paper. The Beck smoothness of the surface of the intermediate layer is adjusted to 50 seconds or longer, preferably 300 seconds or longer, and more preferably 3000 seconds or longer.

Examples of the ionizing radiation-curable resin forming the overcoat layer include the prepolymers and monomers listed below. a) Aliphatic, alicyclic, araliphatic polyhydric alcohols having 2 to 6 valences and poly (meth) acrylates of polyalkylene glycols; b) Aliphatic, alicyclic, araliphatic, aromatics having 2 to 6 valences Poly (meth) acrylate of polyhydric alcohol in the form of addition of alkylene oxide to the polyhydric alcohol of c; poly (meth) acryloyloxyalkyl phosphate ester; d) polyester poly (meth) acrylate; e) epoxy poly ( (Meth) acrylate; f) polyurethane poly (meth) acrylate; g) polyamide poly (meth) acrylate; h) polysiloxane poly (meth) acrylate; i) vinyl having a (meth) acryloyloxy group at the side chain and / or terminal. Or a diene-based low polymer; j) a modified oligoester (meth) acrylate according to the above a) to i); Are listed.

As the monomer, a) a carboxyl group-containing monomer represented by ethylenically unsaturated mono- or polycarboxylic acid or the like and a carboxylic acid group-containing monomer such as an alkali metal salt, ammonium salt or amine salt thereof. B) ethylenically unsaturated (meth) acrylamide or alkyl-substituted (meth) acrylamide, an amide group-containing monomer represented by vinyl lactams such as N-vinylpyrrolidone; c) aliphatic or aromatic vinyl Sulfonic acid group-containing monomers represented by sulfonic acids and alkali metal salts thereof,
Sulfonate group-containing monomers such as ammonium salts and amine salts; d) Hydroxyl group-containing monomers typified by ethylenically unsaturated ethers; e) Dimethylaminoethyl (meth) acrylate-2-
Amino group-containing monomers such as vinyl pyridine; f) Quaternary ammonium base-containing monomers; g) Alkyl esters of ethylenically unsaturated carboxylic acids; h) Nitrile group-containing monomers such as (meth) acrylonitrile; i ) Styrene; j) Esters of ethylenically unsaturated alcohols such as vinyl acetate and (meth) allyl acetate; k) Mono (meth) acrylates of alkylene oxide addition polymers of compounds containing active hydrogen; l) Polybasic acids. Ester group-containing bifunctional monomer typified by diester of ethylene glycol and unsaturated alcohol; m) Bifunctional monomer consisting of diester of alkylene oxide addition polymer of compound containing active hydrogen and (meth) acrylic acid N) bisacrylamide such as N, N-methylenebisacrylamide; o) divinylbenzene, divinylethylene glycol,
Bifunctional monomers such as divinyl sulfone, divinyl ether, and divinyl ketone; p) ester group-containing polyfunctional monomers typified by polyesters of polycarboxylic acids and unsaturated alcohols; q) compounds containing active hydrogen Polyfunctional monomer consisting of polyester of alkylene oxide addition polymer and (meth) acrylic acid; r) Polyfunctional unsaturated monomer such as trivinylbenzene. Etc.

The glass transition point (Tg) after curing is 1
An ionizing radiation curable resin having a temperature of 50 ° C. or higher is particularly preferable because it has an excellent effect of preventing sticking (sticking) to the head in high speed recording. Examples of such a resin include pentaerythritol triacrylate, trimethylolpropane triacrylate, and the like. Examples thereof include polyfunctional monomers such as dipentaerythritol hexaacrylate and tris (acryloxyethyl) isocyanurate, polysiloxane polyacrylates, and tetrafunctional or higher functional oligoester acrylates.

In the present invention, a pigment may be contained in the ionizing radiation curable resin layer, if necessary. Examples of the pigment include inorganic substances such as calcium carbonate, barium carbonate, zinc carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay and colloidal silica. Pigments and pigments obtained by surface-treating these inorganic pigments with organic acids, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin powder, cellulose acetate powder, polymethylmethacrylate powder, fluororesin powder, epoxy resin powder, benzoguanamine resin Organic pigments such as powder and raw starch granules are exemplified.

If the average particle size of the pigment particles is too large, the recording image quality will be deteriorated although the effect of improving the sticking resistance can be obtained. Therefore, the average particle size of 15 μm or less, more preferably 5 μm or less is obtained. It is desirable to use pigments. These pigments are generally dispersed and mixed in a resin component which is cured by ionizing radiation by an appropriate mixing stirrer such as a high speed mixer, and the pigment particles are dispersed by a device such as a kneader or a roll mill that gives a high shearing force.
The effect of the present invention is further exhibited when the particles are dispersed in the secondary particles. Incidentally, in the resin component, in addition to the prepolymers and monomers and pigments as described above, if necessary, for example, a non-ionizing radiation curable resin, a defoaming agent, a leveling agent, a lubricant, a surfactant, a plasticizer, an ultraviolet ray. Additives such as an absorber, a fluorescent dye, a coloring dye, a fluorescent pigment, and a coloring pigment can be appropriately added.

A thermosensitive recording material having a wide range of surface properties from a matte tone to a strong gloss can be formed by adjusting the type and blending ratio of various additives. Examples of non-ionizing radiation curable resins include acrylic resins. , Silicone resin, alkyd resin, fluororesin, butyral resin and the like. The resin component as described above is sufficiently mixed by an appropriate mixing stirrer such as a mixer and then coated on the intermediate layer by various known methods. If necessary, the resin component is heated to adjust the viscosity. You can also do The coating amount is not necessarily limited, but is 0.1 g / m ²
If less than 20 g / m 2, the desired effect of the present invention cannot be expected,
^{If the} coating amount is more than ² , the recording sensitivity of the obtained recording material may be deteriorated. Therefore, it is adjusted in the range of 0.1 to ²⁰ g / m ² , more preferably 0.3 to 10 g / m ² . Is desirable.

As the ionizing radiation for curing the ionizing radiation curable resin, for example, electron beam, ultraviolet ray, α ray, β ray, γ
Ray, X-ray and the like. Since α-rays, β-rays, γ-rays, and X-rays are accompanied by problems such as danger to the human body, electron beams and ultraviolet rays, which are easy to handle and widely used industrially, are preferably used. When the resin layer formed on the intermediate layer is cured by electron beam irradiation, the amount of electron beam irradiated is 0.1 to 15 Mrad, more preferably 0.5 to 1 Mrad.
A range of about 0 Mrad is desirable. If the irradiation is insufficient, the resin component cannot be sufficiently hardened, and on the contrary, excessive electron beam irradiation may cause color development or discoloration of the thermosensitive recording medium.

As the electron beam irradiation method, for example, a scanning method, a curtain beam method, a broad beam method or the like can be adopted, and an accelerating voltage for irradiation is 100.
About 300 KV is suitable. The electron beam irradiation method has advantages that it has higher productivity than ultraviolet irradiation and that there is no problem of odor or coloring due to addition of a sensitizer. When using ultraviolet rays, it is necessary to blend a sensitizer in the coating composition, for example, thioxanthone, benzoin, benzoin alkyl ether xanthone, dimethylxanthone, benzophenone, anthracene, 2,2-diethoxyacetophenone, benzyldimethyl. Ketal, benzyldiphenyl disulfide, anthraquinone, 1-chloroanthraquinone, 2-ethylanthraquinone, 2-te
rt-Butylanthraquinone, N, N'-tetraethyl-
One or more kinds of sensitizers such as 4,4'-diaminobenzophenone and 1,1-dichloroacetophenone are appropriately mixed.

The amount of the sensitizer used is 0.2 to 10% by weight, preferably 0.5 to 5% by weight, based on the ionizing radiation-curable monomer and / or oligomer or prepolymer in the coating composition. It is desirable to adjust within a certain range.
Furthermore, in order to accelerate curing in addition to such a sensitizer,
For example, tertiary amines such as triethanolamine, 2-dimethylaminoethanol, dimethylaminobenzoic acid, isoamyl dimethylaminobenzoate, dioctylaminobenzoic acid, and lauryl dimethylaminobenzoate are used as ionizing radiation-curable monomers in coating compositions. And / or about 0.05 to 3% by weight with respect to the oligomer or the prepolymer can be blended.

As a light source for irradiating ultraviolet rays, 1 to 50 ultraviolet lamps (for example, low pressure, medium pressure and high pressure mercury lamps having an operating pressure of several mmHg to about 10 atm), a xenon lamp, a tungsten lamp and the like are used. 50
Ultraviolet rays having an intensity of about 00 to 8000 μW / cm are irradiated. The recording density and the unevenness of the recording density can be further improved by smoothing the recording material provided with the overcoat layer with a super calender or the like.

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Example 1 Preparation of solution A 3- (N-ethyl-N-isoamylamino) -7- (o
A composition consisting of 20 parts of -chlorophenylamino) fluorane, 20 parts of a 5% aqueous solution of polyvinyl alcohol, and 20 parts of water was pulverized by a sand mill until the average particle size became 2 μm to obtain a liquid A. Preparation of solution B A composition consisting of 30 parts of zinc salt of 4- (3-p-tolylsulfonylpropyloxy) salicylic acid, 30 parts of 5% aqueous solution of polyvinyl alcohol, and 60 parts of water was sand milled until the average particle diameter became 2 μm. It was crushed to obtain a liquid B. Preparation of Solution C A composition consisting of 20 parts of 4,4′-dihydroxybenzophenone, 20 parts of a 5% aqueous solution of polyvinyl alcohol, and 20 parts of water was pulverized with a sand mill until the average particle size became 2 μm, to obtain a solution C. D liquid preparation 1,2-bis (3-methylphenoxy) ethane 20 parts,
20 parts of 5% aqueous solution of polyvinyl alcohol, and water 2
The average particle diameter of the composition consisting of 0 parts was 2 μm using a sand mill.
It was pulverized until it became a liquid D. [Formation of recording layer] A liquid 60 parts, B liquid 120 parts, C liquid 6
0 part, D liquid 60 parts, silicon oxide pigment (oil absorption 180 ml / 100 g)
20 parts, 20% aqueous solution of polyvinyl alcohol 100
Parts and 60 parts of a styrene-butadiene latex having a solid concentration of 40% were mixed and stirred to prepare a recording layer coating liquid. The obtained coating liquid for recording layer was applied on 80 μm synthetic paper (trade name: Yupo FPG, manufactured by Oji Yuka Co., Ltd.) so that the dry weight was 6 g / m ^2, and dried to form a recording layer. [Formation of Intermediate Layer] On the obtained recording layer, an intermediate layer coating liquid consisting of 100 parts of an 8% aqueous solution of polyvinyl alcohol, 10 parts of kaolin, and 10 parts of water was applied at a coating amount of 3 g / m ² after drying. Coated and dried to obtain a Beck smoothness of 5000 after smoothing with a super calender.
An intermediate layer, which is in seconds, was formed. [Formation of Overcoat Layer] 100 parts of oligoester acrylate (Tg after curing is 250 ° C. or more, trade name: M-8030, manufactured by Toagosei Kagaku) on the intermediate layer and calcium carbonate having an average particle diameter of 0.2 μm. 15 parts of the mixed liquid was applied so that the dry coating amount was 4 g / m ^2, and the electron curtain type electron beam irradiation device (CB: 150 type, ESI
(Manufactured by K.K.) at a radiation dose of 3 Mrad to cure the resin component and obtain a thermosensitive recording medium having an overcoat layer.

Examples 2 to 4 Three kinds of solutions were prepared in the same manner as in Example 1 except that the following compounds were used in place of the zinc salt of 4- (3-p-tolylsulfonylpropyloxy) salicylic acid in the preparation of solution B. To obtain a thermosensitive recording medium. Example 2: Zinc salt of 5- (3-p-tolylsulfonylpropyloxy) salicylic acid.

Example 3: Zinc salt of 4- (3-p-methoxyphenylsulfonylpropyloxy) salicylic acid. Example 4: Zinc salt of 4- (4-phenylsulfonylbutyloxy) salicylic acid.

Example 5 In the preparation of solution B, 4 parts was used instead of 30 parts of zinc salt of 4- (3-p-tolylsulfonylpropyloxy) salicylic acid.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 30 parts of-(3-p-tolylsulfonylpropyloxy) salicylic acid and 15 parts of zinc oxide were used.

Examples 6 to 8 Example 1 was repeated except that the following compounds were used in place of 3- (N-ethyl-N-isoamylamino) -7- (o-chlorophenylamino) fluorane in the preparation of solution A.
In the same manner as above, three types of thermal recording materials were obtained. Example 6: 3-Di-n-butylamino-7- (o-chlorophenylamino) fluorane.

Example 7: 3-Diethylamino-7-
(O-Chlorophenylamino) fluorane. Example 8: 3-di-n-butylamino-6-methyl-
7-Phenylaminofluorane.

Examples 9 to 10 Two kinds of thermal recording materials were obtained in the same manner as in Example 1 except that the following compounds were used in place of 4,4'-dihydroxybenzophenone in the preparation of the liquid C. Example 9: 2,4,4'-trihydroxybenzophenone. Example 10: 2,4'-dihydroxybenzophenone.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that in the formation of the recording layer of Example 1, the C liquid was not used and 120 parts of the B liquid was used.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the liquid B was not used and the liquid C was used in an amount of 150 parts in the formation of the recording layer in the first embodiment.

Comparative Example 3 In the same manner as in Example 1, except that the zinc salt of 4- (3-p-tolylsulfonylpropyloxy) salicylic acid was used in place of the zinc salt of 4- (3-p-tolylsulfonylpropyloxy) salicylic acid in the preparation of solution B. A thermosensitive recording medium was obtained.

Comparative Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 4,4'-isopropylidenediphenol was used instead of 4,4'-dihydroxybenzophenone in the preparation of the C liquid.

Comparative Example 5 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 2 except that 4,4'-isopropylidenediphenol was used instead of 4,4'-dihydroxybenzophenone in the preparation of the liquid C.

The 15 types of thermal recording materials thus obtained were evaluated as follows, and the results are shown in [Table 1], [Table 2] and [Table 3]. [Coloring property] Thermosensitive evaluation device [Product name: TH-PMD, manufactured by Okura Electric Co., Ltd.] Applied voltage 24V, pulse period 2.0 msec, pulse width 0.8, 1.0, 1.2, 1.4 msec. The color density and the fog color density on the white paper were measured with a Macbeth densitometer (Macbeth RD-100R type).

[Humidity Resistance] After recording, the thermosensitive recording medium is kept at 40 ° C.
After being left under a high temperature and high humidity condition of 90% RH for 3 days, the recorded image and the color density of the white paper portion were measured with a Macbeth densitometer.

[Heat Resistance] After recording, the thermosensitive recording medium was left under a high temperature condition of 50 ° C. for 3 days, and then the color density of the recorded image and the blank portion was measured with a Macbeth densitometer.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

As is apparent from the results of [Table 1], [Table 2] and [Table 3], the thermosensitive recording medium of the present invention has high sensitivity and high density, and has excellent storability of recorded images, especially halftone. It has excellent storability,
Moreover, it was a heat-sensitive recording material which had no fog coloration and was excellent in raw preservation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichiro Mukoyoshi 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill

Claims (3)

[Claims] 1. A heat-sensitive recording layer containing a colorless or light-colored basic dye and a colorant capable of developing a color on contact with the dye, an intermediate containing a water-soluble resin or a water-dispersible resin. Layer and an overcoat layer containing an ionizing radiation curable resin are sequentially provided, and at least one of salicylic acid derivative represented by [Chemical Formula 1] or a polyvalent metal salt thereof represented by [Chemical Formula 1] as a coloring agent in the thermosensitive recording layer. , And at least one phenol derivative represented by [Chemical Formula 2]. [Chemical 1] [In the formula, X represents a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group or a halogen atom, and A represents C _{2 to} C
_{6 represents} an alkylene group, and 1 represents 0 or an integer of 1 to 5. ] [Chemical 2] [In the formula, Y and Z are each a C _{1 to} C ₄ alkyl group, C
_{1 to} C ₄ alkoxyl group or a halogen atom,
m, n, o, and p each represent 0 or an integer of 1 to 5. However, m and n are not 0 at the same time, and m + o ≦ 5, n
+ P ≦ 5. ] 2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer further contains a metal compound. 3. The thermal recording material according to claim 1, wherein the support is a plastic film or synthetic paper.