JPH11301110A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal recording material with excellent light-fastness. SOLUTION: In a thermal recording layer using a developing compound capable of thermally coloring an ordinarily achromatic or hypochromic coloring compound and a coloring compound, there is provided with a layer containing a copolymer of 2-hydroxybenzotriazole derivative and polymeric vinyl compound expressed by formula (in the formula, R1 shows a hydrogen atom, a halogen atom or a methyl group, R2 shows a hydrogen atom or a 6 or less C alkylene group, a (1-4C) alkylenecarbonyloxy (1-4C) alkylene group or oxy (1-4C) alkylene group, X shows an ester combination, an amid combination, a urethane combination or an ether combination, B is a 4 or less C alkylene group or an amino (1-4C) alkylene group, R5 is a hydrogen atom or a methyl group respectively, and each (m) (n) shows 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having excellent light resistance.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated is disclosed in JP-B-43-4160 and JP-B-45-14039.
And widely used. In general, a thermosensitive recording material is obtained by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing both.
Additives such as binders, sensitizers, fillers, lubricants, etc. are added to this to form a coating solution, which is applied to a support such as paper, film, synthetic paper, etc., and heated to produce a leuco dye and a developer. The color recording is obtained by a chemical reaction that occurs when one or both of them melts and comes into contact. Usually, a sheet-like heat-sensitive recording material is prepared. A thermal printer with a built-in thermal head or the like is used for coloring the heat-sensitive recording sheet. Compared with other recording methods, this thermal recording method (1) produces no noise during recording, (2) does not require development and fixing,
(3) Maintenance-free, (4) Facsimile field, computer output, printer field such as calculator, etc.
It is widely used in the field of recorders for medical measurement, the field of automatic ticket vending machines, the field of heat-sensitive recording labels, and the like.

[0003] In recent years, the use of thermal recording sheets for labels and price tags has increased with the development of POS systems in retail stores, supermarkets, and the like. It is increasingly used for shelf goods such as daily necessities and luxury goods, or for prepaid cards in the transportation-related and service industries.

[0004]

However, conventional heat-sensitive labels found on fresh foods and daily commodities have insufficient water resistance, plasticizer resistance, oil resistance, etc., but insufficient light resistance. However, there is a disadvantage that label printing becomes faint or disappears under sunlight or prolonged illumination. Such a phenomenon is also observed when a thermosensitive color recording type document sheet or facsimile receiving paper is left on a desk or the like, which is also a problem with respect to document storage. This is a major technical challenge in the field of sheets, especially for long-term use and storage. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having excellent light resistance and high color density.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to improve the above-mentioned drawbacks of the thermosensitive recording material, and as a result, completed the present invention. That is, the present invention provides (1) a thermosensitive recording material using a colorless compound which is usually colorless or pale and a color-developing compound capable of forming the color-forming compound upon heating.

[0006]

Embedded image

(In the formula (1), R 1 represents a hydrogen atom, a halogen atom or a methyl group, and R 2 represents a hydrogen atom or a carbon atom having 6 carbon atoms.
In the following alkyl groups, A represents an alkylene group having 4 or less carbon atoms, an alkylene group having 1 to 4 carbon atoms, an alkylenecarbonyloxy (1 to 4 carbon atoms) alkylene group, or an oxy (1 to 4 carbon atoms) alkylene group. X represents an ester bond, an amide bond, a urethane bond or an ether bond, and B represents an alkylene group having 4 or less carbon atoms or amino (having 1 carbon atom).
-4) alkylene groups, R5 represents a hydrogen atom or a methyl group, and m and n are each 0 or 1. )
(2) R1 is a hydrogen atom, a halogen atom or a methyl group, R2 is a thermosensitive recording material comprising a layer containing a copolymer of a 2-hydroxybenzotriazole derivative and a polymerizable vinyl compound represented by Is a hydrogen atom or an alkyl group having 6 or less carbon atoms, A is an alkylene group having 4 or less carbon atoms or an alkylene group having 1 to 4 carbon atoms or 1 to 4 carbon atoms, and X is an ester bond. , R5 is a hydrogen atom or a methyl group, m is 0 or 1, and n is 0, (1) the heat-sensitive recording material, (3) R1
Is a hydrogen atom, a halogen atom or a methyl group bonded to the 5-position, R2 is a hydrogen atom bonded to the 3-position or an alkyl group having 6 or less carbon atoms, and -AX- is bonded to the 5-position ( A C 1-4 alkyleneoxycarbonyl group or an ethylcarbonyloxyethoxycarbonyl group, R5 is a hydrogen atom or a methyl group, m is 1, n
Is 0, (1) the thermosensitive recording material, (4) R1 is a hydrogen atom, a halogen atom or a methyl group bonded to the 5-position,
R2 is a hydrogen atom bonded to the 3-position or an alkyl group having 6 or less carbon atoms, -X- is an oxycarbonyl group bonded to the 5-position, R5 is a hydrogen atom or a methyl group,
m and n are 0, (1) the thermosensitive recording material, and (5) the polymerizable vinyl compound is an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms (1) to (4). The present invention relates to the heat-sensitive recording material of any one of the above.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Formula (1) used in the present invention
In the compound represented by the formula, R1 is a hydrogen atom, a halogen atom or a methyl group. The bonding position to the benzene ring is preferably at the 5-position. Examples of the halogen atom for R1 include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

R 2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms. The bonding position to the benzene ring is preferably the 3-position. Examples of the alkyl group having 6 or less carbon atoms in R2 include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and isopentyl. Group, neopentyl group, tert-pentyl group, n-hexyl group, isohexyl group and the like.

A is an alkylene group having 4 or less carbon atoms,
It is a (1-4 carbon atom) alkylene carbonyloxy (1-4 carbon atom) alkylene group or an oxy (1-4 carbon atom) alkylene group. The bonding position to the benzene ring is preferably at the 5-position. In A, examples of the alkylene group having 4 or less carbon atoms include a methylene group, an ethylene group, a propylene group, a 1-butene group, a 2-butene group, and an isobutylene group. Examples of the (alkylene group having 1 to 4 carbon atoms) include an ethoxycarbonylethyl group, and examples of the oxyalkylene group having 4 or less carbon atoms include, for example, a methyleneoxy group, an ethyleneoxy group, a propoxy group,
Examples thereof include a buteneoxy group, a 2-buteneoxy group, and isobutyleneoxy.

B is an alkylene group having 4 or less carbon atoms or an amino (1-4 carbon atom) alkylene group. In B, the alkylene group having 4 or less carbon atoms includes, for example, a methylene group, an ethylene group, a propylene group, a 1-butene group, a 2-butene group, an isobutylene group, and the like. For example, aminomethylene group, aminoethylene group, aminopropylene group, 1
-Amino-2-butylene group and the like.

X is an ester bond, an amide bond, a urethane bond or an ether bond, and m and n are each 0 or 1. When m is 0, the bonding position of X to the benzene ring is preferably the 5-position.

Preferred combinations of R1, R2, A, B, R5, m and n are, for example, R1 is a hydrogen atom, a halogen atom or a methyl group, R2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms, and A is An alkylene group having 4 or less carbon atoms or an alkylene group having 1 to 4 carbon atoms, alkylenecarbonyloxy (1 to 4 carbon atoms), X is an ester bond, R5 is a hydrogen atom or a methyl group, and m is 0 or 1, respectively. , N is 0.

Specific examples of the compound represented by the formula (1) include, for example, 2 [2'-hydroxy-5 '-(methacryloyloxy) phenyl) benzotriazole,
[2′-Hydroxy-5 ′-(acryloyloxy) phenyl] benzotriazole, 2- [2′-hydroxy-3′-t-butyl-5 ′-(methacryloyloxy)
Phenyl] benzotriazole, 2- [2′-hydroxy-3′-methyl-5 ′-(acryloyloxy) phenyl] benzotriazole, 2- [2′-hydroxy-
5 '-(methacryloyloxypropyl) phenyl]-
5-chlorobenzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-5'-(acryloyloxyethyl) phenyl] benzotriazole, 2- [ 2'-hydroxy-3'-t-butyl-5 '
-(Methacryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -5-chlorobenzotriazole, 2- [2'-hydroxy-5'-(acryloyloxy) Butyl) phenyl] -5-methylbenzotriazole, 2- [2'-hydroxy-3'-t-
Butyl-5 '-(acryloyloxyethoxycarbonylethyl) phenyl] benzotriazole and the like.

Examples of the vinyl compound copolymerizable with the compound of the formula (1) include acrylonitrile, alkyl (meth) acrylate, alkyl vinyl ether, alkyl vinyl ester, and styrene. Is not particularly limited, but is preferably 1 to 20. The following are specific examples of these compounds.

Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-
Ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether,
Examples include stearyl vinyl ether, vinyl acetate, ethyl vinyl, bitilbunyl, 2-ethylhexyl vinyl and the like.

The copolymerization ratio of the compound of the formula (1) to the vinyl compound is preferably in the range of the compound of the formula (1): the vinyl compound = 5: 95 to 60:40 by weight.

The copolymer obtained by reacting the 2-hydroxybenzotriazole derivative of the formula (1) of the present invention with a polymerizable vinyl compound is preferably used in the form of an aqueous emulsion when used, for example, as described in JP-A-6-73368. It is manufactured by the method described in Japanese Patent Application Laid-Open No. Hei 7-126536.

The heat-sensitive recording material of the present invention is provided on a support with a heat-sensitive color-forming layer mainly composed of a colorless or pale-colored color-forming compound and a color-developing compound capable of coloring the color-forming compound when heated. Further, an overcoat layer is provided on the heat-sensitive coloring layer, and when a copolymer of the compound of the formula (1) and the polymerizable vinyl compound is contained in the heat-sensitive coloring layer, the heat-sensitive coloring layer is formed by the formula (1) ) Is a layer containing a copolymer of the compound of the compound and the polymerizable vinyl compound, and when the layer is contained in the overcoat layer, the overcoat layer contains a copolymer of the compound of the formula (1) and the polymerizable vinyl compound. Layer. As the support, for example, paper, plastic sheet,
A sheet-like material such as synthetic paper is preferred.

In the present invention, when the thermosensitive coloring layer is a layer containing a copolymer of the compound of the formula (1) and the polymerizable vinyl compound, the content of the copolymer depends on the total amount of the thermosensitive coloring layer. 1 to 60% by weight, preferably 5%, based on 100% by weight
To 30% by weight, for example, 1 to 5
0% by weight, 5-80% by weight of a color-developing compound, 0-80% by weight of each of a binder, a filler and a heat-fusible compound (sensitizer), other lubricants, surfactants, defoamers, etc. Are used at arbitrary ratios, for example, 0 to 30% by weight, respectively. The weight% is the weight ratio of each component in the thermosensitive coloring layer.

When the overcoat layer is a layer containing a copolymer of the compound of the formula (1) and a polymerizable vinyl compound, the copolymer is contained in the overcoat layer. 5 to 95 with the total weight as 100%
% By weight, preferably 40 to 90% by weight. still,
The copolymer may be contained in both the thermosensitive coloring layer and the overcoat layer.

The color-forming compound used in the heat-sensitive coloring layer is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. As a specific example,
Examples include fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds.

As the fluoran compound, for example, 3-
Diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-N-isopentylamino) -6-methyl-7
-Anilinofluoran, 3-isobutylethylamino-
6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-
Hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino)
-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-
7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluoran, 3- (p-toluidine Noethylamino)
-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino)
Fluorane, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-
Fluoroanilino) fluoran, 3-dibutylamino-
7- (o-fluoroanilino) fluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro -7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-
7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-
Methylfluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-phenylfluoran, 3- (p-toluidinoethylamino) -6
-Methyl-7-phenethylfluoran and the like.

Examples of tolyl methane compounds include 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (alias: crystal violet lactone or CVL), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindole- 3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3-
(2-phenylindol-3-yl) phthalide, 3,
3-bis (1,2-dimethylindol-3-yl)-
5-dimethylaminophthalide, 3,3-bis (1,2-
Dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazole-3)
-Yl) -5-dimethylaminophthalide, 3,3- (2
-Phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-
(1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

Further, as the spiro compound, for example, 3
-Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzopyran ) Spiropyran, 1,3,3-trimethyl-6
-Nitro-8'-methoxyspiro (indoline-2,
2'-benzopyran) and the like, and examples of the diphenylmethane-based compound include N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, and N-2,4,5-trichlorophenyl. Leuco auramine and the like, as thiazine compounds, for example, benzoyl leucomethylene blue, p
-Nitrobenzoyl leucomethylene blue and the like; lactam compounds such as rhodamine B anilinolactam and rhodamine Bp-chloroanilinolactam; and fluorene compounds such as 3,6-bis (dimethylamino) fluorene Spiro (9,3 ')-
6′-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenespiro (9,3 ′) -6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color developing compound is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper.
For example, a phenolic compound, an aromatic carboxylic acid derivative having a phenolic hydroxyl group, an aromatic carboxylic acid or a metal salt thereof, and the like can be given.

As the phenolic compound, for example, α-
Naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-
Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (also called bisphenol A)
Or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p-hydroxyphenyl)
Cyclohexane, 4,4′-thiobisphenol, 4,
4'-cyclohexylidenediphenol, 2,2'-
(2,5-dibromo-4-hydroxyphenyl) propane, 4,4-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4′-dihydroxydiphenylsulfone 2,4′-dihydroxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
-Hydroxy-4'-methoxydiphenyl sulfone, 4
-Hydroxy-4'-ethoxydiphenyl sulfone, 4
-Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone and the like.

Examples of the aromatic carboxylic acid derivative or aromatic carboxylic acid include methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, 2,4 Phenolic compounds such as -dihydroxy-2'-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and the like.

Examples of usable binders include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, and the like. Aqueous solutions such as polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salts of styrene / maleic anhydride copolymers, and iso (or diiso) butylene / maleic anhydride copolymer salts Of nature or styrene /
Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, polyvinyl acetate, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polystyrene, Hydrophobicity of acrylic resin, acrylic / styrene resin, polyacrylate, polyester, polycarbonate, polyurethane, polybutyral, epoxy resin, furan resin, vinyltoluene resin, rosin ester resin, composite particles of colloidal silica and acrylic copolymer, etc. Polymer compounds or their emulsions.

Examples of the filler that can be used include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, and acrylic resin. , Polyolefin resins, benzoguanamine resins, melamine resins, urea-formalin resins and the like.

Examples of the heat-fusible compound that can be used include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, aromatic ethers, and the like. Aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives,
Biphenyl derivatives, terphenyl derivatives, and the like that are solid at room temperature and have a melting point of about 70 ° C. or more can be used.

Examples of waxes include wood wax, carnauba wax, shellac, paraffin, montan wax,
Paraffin oxide, polyethylene wax, polyethylene oxide and the like, as higher fatty acids, for example, stearic acid,
Examples of higher fatty acid amides such as behenic acid include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, and ethylenebisstearin Examples of acid amides include higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide, and examples of acetylated aromatic amines include acetotoluizide.

As the naphthalene derivative, for example, 1
-Benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like, as aromatic ethers, for example, 1,2-diphenoxyethane, 1,4-diphenoxyethane, 1,2-bis ( 3-methylphenoxy) ethane, 1,2-bis (4
-Methoxyphenoxy) ethane, 1,2-bis (3,4
-Dimethylphenyl) ethane, 1-phenoxy-2-
(4-chlorophenoxy) ethane, 1-phenoxy-2
Examples of aromatic carboxylic acid derivatives include-(4-methoxyphenoxy) ethane and the like. Examples of aromatic carboxylic acid derivatives include p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, terephthalic acid dibenzyl ester and the like. Derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, and the like. Carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate. (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like include biphenyl derivatives such as p-benzylbiphenyl and p-benzylbiphenyl.
-Allyloxybiphenyl and the like, and terphenyl derivatives include, for example, m-terphenyl and the like.

Other lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents and the like are added as required.

Using the above materials, the thermal recording material of the present invention is prepared, for example, by the following method. That is, first, the color-forming compound and the color-developing compound are separately pulverized and dispersed in a dispersing machine such as a ball mill, an attritor, and a sand mill together with a binder or other additives as necessary (pulverization, When the dispersion is carried out by a wet method, water is usually used as a medium). Separately, an aqueous emulsion obtained by emulsion polymerization of the compound of the formula (1) and a polymerizable vinyl compound is mixed to prepare a thermosensitive coloring layer coating solution. Usually, on a support such as a sheet or synthetic paper, the dry weight is 1
２０20 g / m 2 (square meter) by a bar coater, blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 2: 1 to 1: 1 by dry weight ratio).
0) and dried to obtain the heat-sensitive recording material of the present invention.

When the overcoat layer contains a copolymer of the compound of the formula (1) and a polymerizable vinyl compound, the copolymer may be heat-sensitive together with a binder, a filler and other additives, if necessary. After forming the overcoat layer coating solution in the same manner as in the preparation of the color forming layer coating solution, the dry weight is usually 0.1 to 10 g / m2 (square meter), preferably 0.5 to 3 g / m2 ( (Square meter).

The heat-sensitive recording material of the present invention, which contains a copolymer of a 2-hydroxybenzotriazole derivative of the formula (1) and a polymerizable vinyl compound in the heat-sensitive coloring layer and / or a layer thereon, has excellent light fastness. ing.

[0038]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight.

Example 1 (Formation of thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 2 μm or less, and the solution [A] and the solution [B] were respectively obtained. Prepare. [A] solution: 3-dibutylamino-7- (o-chloroanilino) fluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts 25% Emulsion of 30 parts of 2- [2'-hydroxy-5 '-(methacryloyloxy) phenyl] benzotriazole, 60 parts of butyl acrylate, and 30 parts of ethyl acrylate After polymerization, an aqueous emulsion of a copolymer corresponding to the formula (1) (solids concentration 40
%) [C] solution is prepared.

Next, the respective preparations were mixed at the following ratio to prepare a coating solution for the thermosensitive coloring layer, and the basis weight was 50 g / m 2 (square meter).
(G) and dried to obtain a heat-sensitive coloring layer on a high-quality paper having a dry weight of 8 g / m 2 (square meter). [A] liquid 8 parts [B] liquid 16 parts [C] liquid 10 parts 20% methylol stearic acid amide aqueous dispersion 15 parts 50% calcium carbonate aqueous dispersion 10 parts Water 21 parts (formation of protective layer) Is coated on the thermosensitive coloring layer so as to have a dry weight of 3 g / m @ 2 (square meter) and dried to obtain the thermosensitive recording material of the present invention. 15% PVA aqueous solution 100 parts 50% clay dispersion 10 parts 30% glyoxal aqueous solution 1 part

Examples 2 to 8 In the same manner as in Example 1 except that the solution [C] of Example 1 was replaced with a 40% aqueous emulsion of a copolymer produced at a monomer component ratio shown in Table 1 below. The heat-sensitive recording material of the present invention is obtained.

[0042]

TABLE 1 Monomer component ratio of copolymer Example 2-Hydroxybenzophenone derivative / vinyl compound 22 2- [2'-hydroxy-5 '-(acryloyloxy) phenyl] benzotriazole 30 parts 2-ethylhexyl acrylate 80 Part 3 2- [2'-hydroxy-3'-t-butyl-5 '-(methacryloyloxy) phenyl] benzotriazole 30 parts n-butyl acrylate 70 parts ethyl acrylate 20 parts 4 2- [2'-hydroxy-5 '-(Methacryloyloxy) phenyl] -5-chlorobenzotriazole 30 parts butyl acrylate 70 parts 5 2- [2'-hydroxy-5'-(methacryloyloxy) phenyl] benzotriazole 30 parts acrylonitrile 70 parts 6 2- [2 '-Hydroxy-5'- (Acryloyloxy) phenyl] benzotriazole 30 parts vinyl acetate 60 parts methyl methacrylate 30 parts 7 2- [2'-hydroxy-3'-t-butyl-5 '-(methacryloyloxy) phenyl] benzotriazole 30 parts styrene 80 parts ethyl Methacrylate 10 parts 8 2- [2'-hydroxy-5 '-(methacryloyloxy) phenyl] -5-chlorobenzotriazole 30 parts Acrylonitrile 80 parts Butyl methacrylate 10 parts

Example 9 In place of 3-dibutylamino-7- (o-chloroanilino) fluoran of Example 1, 3-dibutylamino-6-
The heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using methyl-7-anilinofluoran.

Example 10 In place of 3-dibutylamino-7- (o-chloroanilino) fluoran of Example 1, 3-dipentylamino-6
Example 1 using -methyl-7-anilinofluoran
To obtain the heat-sensitive recording material of the present invention.

Example 11 The present invention was repeated in the same manner as in Example 1 except that bis (3-allyl-4-hydroxyphenyl) sulfone of Example 1 was replaced with 4-hydroxy-4′-isopropoxydiphenyl sulfone. A heat-sensitive recording material is obtained.

Example 12 (Formation of thermosensitive coloring layer) Each of the prepared solutions was mixed at the following ratio to prepare a coating solution for the thermosensitive coloring layer, and dried on a high quality paper having a basis weight of 50 g / m 2 (square meter). Is applied so as to have a weight of 8 g / m @ 2 (square meter) and dried to obtain a thermosensitive coloring layer. [A] Liquid 8 parts [B] Liquid 16 parts 20% methylol stearic acid amide aqueous dispersion 15 parts 50% calcium carbonate aqueous dispersion 10 parts 50% carboxylated styrene / butadiene copolymer latex 8 parts Water 21 parts

(Formation of Protective Layer) Further, a protective layer coating solution having the following ratio was dried on the thermosensitive coloring layer by a weight of 3%.
g / m2 (square meter) and dried to obtain the heat-sensitive recording material of the present invention. Solution [C] described in Example 1 30 parts 30% aqueous solution of zinc stearate 10 parts 50% clay dispersion 10 parts

Comparative Example 1 A comparative thermosensitive recording material was obtained in the same manner as in Example 1 except that the liquid [C] described in Example 1 was replaced with a 50% carboxylated styrene / butadiene copolymer latex.

Table 2 shows the quality performance of the heat-sensitive recording materials of the present invention and the heat-sensitive recording materials for comparison of Examples 1 to 12 obtained as described above.

[0050]

Table 1 Quality performance test Background 1) Color density 2) Lightfast background 3) Lightfast image 3) Example 1 0.05 1.55 0.08 1.53 Example 2 0.05 1 0.54 0.08 1.53 Example 3 0.05 1.55 0.08 1.54 Example 4 0.05 1.55 0.08 1.53 Example 5 0.05 1.55 0.08 1.54 Example 6 0.05 1.56 0.09 1.53 Example 7 0.05 1.55 0.08 1.54 Example 8 0.05 1.54 0.08 1.54 Example 9 0.06 1.57 0.09 1.56 Example 10 0.05 1.56 0.08 1.56 Example 11 0.05 1.55 0.07 1.51 Example 12 0.05 1 .56 0.07 1.55 Comparative Example 1 0.05 1.54 0.25 0.99

1) Background: A value measured by a Macbeth reflection densitometer RD-914 of an uncolored sample. 2) Color density: Thermal printer (D
-805P) Macbeth reflection densitometer R of the colored portion printed with
Measured value with model D-914. 3) Light fastness: A value measured by a Macbeth reflection densitometer RD-914 of a color-developed portion of the sample after leaving the sample colored by the above-mentioned printer at the southern window exposed to sunlight for one week.

As is clear from the table, the heat-sensitive recording material of the present invention has excellent light fastness in the background portion and the color image portion.

[0053]

According to the present invention, 2 represented by the formula (1)
-By containing a copolymer of a hydroxybenzotriazole derivative and a polymerizable vinyl compound in the thermosensitive coloring layer and / or a layer thereon, the background and the lightfastness of the coloring image are remarkably excellent as compared with those conventionally known. Heat-sensitive recording material is obtained.

Claims (5)

[Claims] 1. A heat-sensitive recording material comprising a colorless or pale-colored color-forming compound and a color-developing compound capable of causing the color-forming compound to develop a color when heated, which is represented by the following formula (1). (In the formula (1), R1 is a hydrogen atom, a halogen atom or a methyl group, R2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms, A is an alkylene group having 4 or less carbon atoms, (C1 -4) alkylenecarbonyloxy (1-4 carbon atoms) alkylene group or oxy (1 carbon atom)
4) an alkylene group, X is an ester bond, an amide bond,
B represents an alkylene group having 4 or less carbon atoms or an amino (C1-4) alkylene group; R5 represents a hydrogen atom or a methyl group; m and n each represent 0 or It is one. A heat-sensitive recording material comprising a layer containing a copolymer of a 2-hydroxybenzotriazole derivative represented by the formula (1) and a polymerizable vinyl compound. 2. R1 is a hydrogen atom, a halogen atom or a methyl group, R2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms, A is an alkylene group having 4 or less carbon atoms or an alkylene group having 1 to 4 carbon atoms. The thermosensitive recording material according to claim 1, wherein carbonyloxy (C1-4) alkylene group, X is an ester bond, R5 is a hydrogen atom or a methyl group, m is 0 or 1, and n is 0. R3 is a hydrogen atom, a halogen atom or a methyl group bonded to the 5-position, R2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms bonded to the 3-position, and -AX
-Is an alkyleneoxycarbonyl group or an ethylcarbonyloxyethoxycarbonyl group having 1 to 4 carbon atoms bonded to the 5-position, R5 is a hydrogen atom or a methyl group, m is 1 and n is 0. 1. Thermal recording material. 4. R1 is a hydrogen atom, a halogen atom or a methyl group bonded to the 5-position; R2 is a hydrogen atom or an alkyl group having 6 or less carbon atoms bonded to the 3-position; The thermosensitive recording material according to claim 1, wherein R5 is a hydrogen atom or a methyl group, and m and n are 0. 5. The heat-sensitive recording material according to claim 1, wherein the polymerizable vinyl compound is an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms.