JPH07329426A - Thermal recording material - Google Patents

Abstract

(57) [Summary] [Structure] A heat-sensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, wherein the electron-accepting compound contains a compound represented by the formula (1). [Effect] A heat-sensitive recording material excellent in storage stability of an uncolored part and a colored image is provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal recording material. More specifically, it relates to a heat-sensitive recording material which is excellent in storage stability of uncolored portions and colored images.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording material utilizing a color reaction between an electron-donating color-forming compound and an electron-accepting compound (developing agent) is well known (for example, Japanese Patent Publication No. 43-4).
160, JP-B-45-14039). The heat-sensitive recording material is relatively inexpensive and has the advantage that the recording device is compact and maintenance-free, and is therefore widely used in the fields of facsimiles, recorders and printers. Recently, the fields of use of thermal recording materials have expanded and diversified, and have expanded to applications (for example, labels and prepaid cards) under harsh environments. However, conventionally known heat-sensitive recording materials containing 2,2-bis (4'-hydroxyphenyl) propane ["bisphenol A"], 4-hydroxybenzoic acid benzyl ester and the like as electron-accepting compounds are not suitable for harsh environments. (For example, under contact with a writing instrument such as oil, solvent, oil and fat, or a highlighter pen, or in a humid environment, the uncolored part may be significantly contaminated (ground stain), or the colored image may fade. There are drawbacks. At present, there is a demand for a heat-sensitive recording material that is excellent in storage stability of uncolored portions and colored images.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having improved storage stability of uncolored areas and colored images.

[0004]

The present inventors have arrived at the present invention as a result of earnest studies on a heat-sensitive recording material in order to meet the above-mentioned demand. That is, the present invention relates to a heat-sensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, wherein the electron-accepting compound contains a compound represented by the formula (1) or (2). It is about materials.

[0005]

[Chemical 2]

A compound represented by the formula (1) according to the present invention,
That is, 2- (α, α-dimethyl-4′-hydroxybenzyl) -4- (α, α-dimethyl-3 ′, 4′-dihydroxybenzyl) phenol can be obtained by a method known per se (for example, Japanese Patent Laid-Open Publication No. -116190 gazette). For example, it can be produced by reacting about 2 mol of 4-isopropenylphenol with 1 mol of catechol in the presence of hydrohalic acid. The melting point of the compound represented by the formula (1) is
163-165 ° C. In the heat-sensitive recording material of the present invention, the amount of the compound represented by the formula (1) used is
Although not particularly limited, it is usually about 50 to 700 parts by weight with respect to 100 parts by weight of the electron-donating color forming compound,
It is preferable to use about 100 to 500 parts by weight.

The colorless or light-colored electron-donating color-forming compound used in the heat-sensitive recording material of the present invention is not particularly limited, but triarylmethane compounds, vinylphthalide compounds, diarylmethane compounds, rhodamine-type compounds. Lactam compounds, thiazine compounds, fluorane compounds, pyridine compounds, spiro compounds, various known electron-donating color-forming compounds such as fluorene compounds, and more preferably fluoran compounds, among which the general formula The fluoran compound represented by (A) (Chemical Formula 3) is preferable.

[0008]

[Chemical 3] (In the formula, A and B are an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkoxyalkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a tetrahydrofurfuryl group. Further, A and B may form a heterocycle with adjacent nitrogen atoms, and Z ₁ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a halogen atom. Z ₂ and Z ₃ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen atom or a trifluoromethyl group)

Specific examples of the electron-donating color forming compound include triarylmethane compounds, for example,
3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide ["crystal violet lactone"], 3,3-bis (4-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) −
3- (4-diethylamino-2-methylphenyl) -6
-Dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1,2-dimethylindole-3-
Yl) phthalide, 3- (4-dimethylaminophenyl)
-3- (2-methylindol-3-yl) phthalide,
3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-3-yl)
-6-Dimethylaminophthalide and the like.

Examples of vinylphthalide compounds include 3,3-bis [1,1-bis (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, and , 3-bis [1,1-bis (4
-Pyrrolidinophenyl) ethylene-2-yl] -4,
5,6,7-Tetrabromophthalide, 3,3-bis [1
-(4-Dimethylaminophenyl) -1- (4-methoxyphenyl) ethylene-2-yl] -4,5,6,7-
Tetrachlorophthalide, 3,3-bis [1- (4-pyrrolidinophenyl) -1- (4-methoxyphenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, etc. is there.

Examples of the diarylmethane compound include 4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine,
N-2,4,5-trichlorophenyl leuco auramine and the like. As the rhodamine-lactam compound,
For example, rhodamine-B-anilinolactam, rhodamine- (4-nitroanilino) lactam, rhodamine-B
-(4-chloroanilino) lactam and the like. Examples of thiazine compounds include 3,7-bis (diethylamino) -10-benzoylphenoxazine, benzoylleuco methylene blue, and 4-nitrobenzoylmethylene blue.

Examples of fluoran compounds include:
3,6-dimethoxyfluorane, 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-cyclohexyl-Nn-butylamino-7-methylfluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-
Octylaminofluorane, 3-diethylamino-7-
Di-n-hexylaminofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7
-(2'-fluorophenylamino) fluorane, 3-diethylamino-7- (2'-chlorophenylamino) fluorane, 3-diethylamino-7- (3'-chlorophenylamino) fluorane, 3-diethylamino-7-
(2 ', 3'-dichlorophenylamino) fluorane, 3-
Diethylamino-7- (3'-trifluoromethylphenylamino) fluorane, 3-di-n-butylamino-7
-(2'-fluorophenylamino) fluorane, 3-di-n-butylamino-7- (2'-chlorophenylamino) fluorane,

3-N-isopentyl-N-ethylamino-7- (2'-chlorophenylamino) fluorane, 3-
N-n-hexyl-N-ethylamino-7- (2'-chlorophenylamino) fluorane, 3-diethylamino-
6-chloro-7-anilinofluorane, 3-di-n-butylamino-6-chloro-7-anilinofluorane, 3
-Diethylamino-6-methoxy-7-anilinofluorane, 3-di-n-butylamino-6-ethoxy-7-
Anilinofluorane, 3-pyrrolidino-6-methyl-7
-Anilinofluorane, 3-piperidino-6-methyl-
7-anilinofluorane, 3-morpholino-6-methyl-7-anilinofluorane, 3-dimethylamino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di-n-
Butylamino-6-methyl-7-anilinofluorane,
3-di-n-pentylamino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-methylamino-6
-Methyl-7-anilinofluorane, 3-N-n-propyl-N-methylamino-6-methyl-7-anilinofluorane, 3-N-n-propyl-N-ethylamino-
6-Methyl-7-anilinofluorane, 3-N-n-butyl-N-methylamino-6-methyl-7-anilinofluorane, 3-N-n-butyl-N-ethylamino-6
-Methyl-7-anilinofluorane, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluorane, 3-N-isobutyl-N-ethylamino-6-
Methyl-7-anilinofluorane, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluorane, 3-Nn-hexyl-N-methylamino-6
-Methyl-7-anilinofluorane,

3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluorane, 3-N-cyclohexyl-N-n-propylamino-6-methyl-
7-anilinofluorane, 3-N-cyclohexyl-N
-N-butylamino-6-methyl-7-anilinofluorane, 3-N-cyclohexyl-Nn-hexylamino-6-methyl-7-anilinofluorane, 3-N-cyclohexyl-Nn -Octylamino-6-methyl-
7-anilinofluorane, 3-N-2'-methoxyethyl-N-methylamino-6-methyl-7-anilinofluorane, 3-N-2'-methoxyethyl-N-ethylamino-6- Methyl-7-anilinofluorane, 3-N-2'-
Methoxyethyl-N-isobutylamino-6-methyl-
7-anilinofluorane, 3-N-2'-ethoxyethyl-N-methylamino-6-methyl-7-anilinofluorane, 3-N-2'-ethoxyethyl-N-ethylamino-6- Methyl-7-anilinofluorane, 3-N-3'-
Methoxypropyl-N-methylamino-6-methyl-7
-Anilinofluorane, 3-N-3'-methoxypropyl-N-ethylamino-6-methyl-7-anilinofluorane, 3-N-3'-ethoxypropyl-N-methylamino-6-methyl -7-anilinofluoran, 3-N-3 '
-Ethoxypropyl-N-ethylamino-6-methyl-
7-anilino fluoran,

3-N-2'-tetrahydrofurfuryl-N
-Ethylamino-6-methyl-7-anilinofluorane, 3-N- (4'-methylphenyl) -N-ethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-ethyl -7-anilinofluoran, 3-
Diethylamino-6-methyl-7- (3'-methylphenylamino) fluorane, 3-diethylamino-6-methyl-7- (2 ', 6'-dimethylphenylamino) fluorane, 3-di-n-butylamino- 6-methyl-7-
(2 ', 6'-Dimethylphenylamino) fluorane, 3-
Di-n-butylamino-7- (2 ', 6'-dimethylphenylamino) fluorane, 2,2-bis [4'-(3-N-
Cyclohexyl-N-methylamino-6-methylfluorane) -7-ylaminophenyl] propane, 3- [4 '
-(4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane and the like.

Examples of pyridine compounds include 3-
(2-Ethoxy-4-diethylaminophenyl) -3-
(1-octyl-2-methylindol-3-yl)-
4 or 7-azaphthalide, 3- (2-ethoxy-4-
Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2- Methylindole-
3-yl) -4 or 7-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide, 3- ( 2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide.

Examples of spiro compounds include 3-methyl-spiro-dinaphthopyran and 3-ethyl-spiro-
Dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) spiropyran, 3
-Propyl-spiro-dibenzopyran and the like. Examples of the fluorene compound include 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide and 3,6-bis (diethylamino) fluorene-9-spiro-3. Examples include '-(6'-dimethylamino) phthalide. Of course, it is not limited to these electron donating color forming compounds, and these electron donating color forming compounds may be used alone or in combination.

The heat-sensitive recording material of the present invention is characterized by containing a compound represented by the formula (1) as an electron-accepting compound, within a range that does not impair the desired effects of the present invention. It is also possible to use other electron-accepting compounds in combination. In this case, the proportion of the compound represented by the formula (1) in all electron-accepting compounds is usually 10% by weight or more, preferably 20% by weight or more, more preferably 3% by weight.
It is desirable to adjust it to 0% by weight or more. The electron-accepting compound other than the compound represented by the formula (1) is not particularly limited, but an organic electron-accepting compound such as a phenol derivative or a metal salt thereof, an organic acid derivative or a metal salt, a complex, a urea derivative and the like. Examples include various known electron-accepting compounds such as organic compounds and inorganic electron-accepting compounds.

Specific examples of the electron accepting compound other than the compound represented by the formula (1) include, for example, 4-tert-butylphenol, 4-tert-octylphenol, 4-phenylphenol, 1-naphthol and 2-naphthol. , Hydroquinone, resorcinol, 4-tert-octylcatechol, 2,2'-dihydroxybiphenyl, 4,4'-
Dihydroxydiphenyl ether, 2,2-bis (4'-
Hydroxyphenyl) propane ["bisphenol A"], 1,1-bis (4'-hydroxyphenyl) cyclohexane, 2,2-bis (4'-hydroxy-3'-methylphenyl) propane, 1,3-bis ( 4'-hydroxycumyl) benzene, 1,4-bis (4'-hydroxycumyl) benzene, 1,3,5-tris (4'-hydroxycumyl) benzene, 2,2-bis (4'- Hydroxyphenyl) acetic acid ethyl ester, 4,4- (4′-hydroxyphenyl) pentanoic acid-n-butyl ester, 4-hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid phenethyl ester, 2,4-dihydroxybenzoic acid phenoxy ester Ethyl ester, 4-hydroxyphthalic acid dimethyl ester, gallic acid-n-propyl ester, gallic acid-n-octyl ester Gallic acid-n-dodecyl ester, gallic acid-n-octadecyl ester,

Hydroquinone monobenzyl ether, bis (3-methyl-4-hydroxyphenyl) sulfide, bis (2-methyl-4-hydroxyphenyl) sulfide, bis (3-phenyl-4-hydroxyphenyl) sulfide, bis (3 -Cyclohexyl-4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (3-phenyl-4-hydroxy) Phenyl) sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-tert-
Butyldiphenyl sulfone, 4-hydroxy-4'-chlorodiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-n-
Propoxydiphenyl sulfone, 4-hydroxy-4 '
-Isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-butoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone,
3,4-dihydroxy-4'-methyldiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone,

2-methoxy-4'-hydroxydiphenyl sulfone, 2-ethoxy-2'-hydroxydiphenyl sulfone, 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone, bis (2-hydroxy-5- tert-butylphenyl) sulfone, bis (2-
Hydroxy-5-chlorophenyl) sulfone, bis [4- (3'-hydroxyphenyloxy) phenyl] sulfone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 4,4'-dihydroxy Benzophenone,
1,7-di (4'-hydroxyphenylthio) -3,5-
Phenol derivatives such as dioxaheptane and 1,5-di (4'-hydroxyphenylthio) -3-oxapentane, or metal salts of these phenol derivatives (for example, metal salts such as nickel, zinc, aluminum and calcium) ,

For example, 4- (2'-phenoxyethoxy)
Salicylic acid, 4- [2 '-(4-methoxyphenoxy) ethoxy] salicylic acid, 5- [4'-(2- [4-methoxyphenoxy] ethoxy) cumyl] salicylic acid, 4- [3 '
-(4-Methylphenylsulfonyl) propoxy] salicylic acid, 4-n-butyloxycarbonylaminosalicylic acid, 4-n-octyloxycarbonylaminosalicylic acid, 4-n-nonyloxycarbonylaminosalicylic acid, 4-n-decyloxycarbonylamino Salicylic acid, 5-cyclohexyloxycarbonylamino salicylic acid, 1-naphthoic acid, 2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid,
2-hydroxy-6-naphthoic acid, 1-acetyloxy-2-naphthoic acid, 2-acetyloxy-1-naphthoic acid, 2-acetyloxy-3-naphthoic acid, phthalic acid monobenzyl ester, phthalic acid monophenyl ester ,
Isophthalic acid, terephthalic acid, 4-methylbenzoic acid, 2
-Benzoylbenzoic acid, 2- (4'-chlorobenzoyl)
Benzoic acid, 4-nitrobenzoic acid, 4-chlorobenzoic acid,
Organic acid derivatives such as 4-trifluoromethylbenzoic acid, 4-formylbenzoic acid, 4-cyanobenzoic acid and stearic acid, or metal salts of these organic acid derivatives (for example, metals such as nickel, zinc, aluminum and calcium). salt),

Complexes such as zinc thiocyanate antipyrine complex and molybdic acid acetylacetone complex, for example, N, N'-diphenylthiourea, N, N'-di (3-trifluoromethylphenyl) thiourea, N,
N'-di (3-chlorophenyl) thiourea, 1,4-di (3'-chlorophenyl) -3-thiosemicarbazide, N
-Electron-accepting compounds such as urea derivatives such as -phenyl-N '-(4-methylphenylsulfonyl) urea and 4,4'-bis (4 "-methylphenylsulfonylcarbonylamino) diphenylmethane, for example, acid clay, attapulgite Inorganic electron accepting compounds such as activated clay, activated clay, aluminum chloride, zinc chloride, zinc bromide, etc. can be mentioned, but not limited to these compounds. You can also

Furthermore, by adding a heat-fusible compound (a compound having a melting point of about 70 to 150 ° C., more preferably a melting point of about 80 to 130 ° C.) as a sensitizer to the heat-sensitive recording material of the present invention, It is possible to obtain a heat-sensitive recording material compatible with higher speed recording. In this case, the amount of the heat-fusible compound used is not particularly limited, but is usually 10 to 700 parts by weight, relative to 100 parts by weight of the electron-donating color forming compound.
It is preferable to use 20 to 500 parts by weight.

Specific examples of the heat-fusible compound 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- Ethylcapric acid amide, N-butyllauric acid amide, N-methylstearic acid amide, N-methyloleic acid amide, N-stearylcyclohexylamide, N-octadecylacetamide, N-oleinacetamide, stearylurea, stearic acid anilide, benzanilide , Linoleic acid anilide, acetoacetic acid anilide, o-acetoacetic acid toluidide, p-acetoacetic acid anisidide, N-ethylcarbazole, 4-methoxydiphenylamine, N-hydroxymethylstearic acid amide,
Nitrogen-containing compounds such as ethylenebisstearic acid amide,
For example, 4-benzyloxybenzoic acid benzyl ester, 2-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di ( 4-chlorobenzyl) ester, adipic acid diphenyl ester, glutaric acid diphenacyl ester, di (4-methylphenyl) carbonate, terephthalic acid dibenzyl ester, and the like,

Hydrocarbon compounds such as 4-benzylbiphenyl, m-terphenyl, fluorene, fluoranthene, 2,6-diisopropylnaphthalene and 3-benzylacenaphthene, for example, 2-benzyloxynaphthalene, 2- (4 ' -Methylbenzyloxy) naphthalene, 1,4-diethoxynaphthalene, 1,2-diphenoxyethane, 1,2-bis (3'-methylphenoxy) ethane, 1-phenoxy-2- (4'-methylphenoxy)
Ethane, 1-phenoxy-2- (4'-ethylphenoxy) ethane, 1- (4'-methoxyphenoxy) -2-phenoxyethane, 1- (4'-methoxyphenoxy) -2
-(3'-methylphenoxy) ethane, 1- (4'-methoxyphenoxy) -2- (2'-methylphenoxy) ethane, 1,2-bis (4'-methoxyphenylthio) ethane, 1,5- Bis (4'-methoxyphenoxy) -3-oxapentane, 1,4-bis (2'-vinyloxyethoxy) benzene, 4- (4'-methylphenoxy) biphenyl, 1,4-bis (2'-chloro Benzyloxy) benzene, 4,4′-di-n-butoxydiphenyl sulfone,
1,2-diphenoxybenzene, 1,4-bis (2'-chlorophenoxy) benzene, 1,4-bis (4'-methylphenoxy) benzene, 1,4-bis (3'-methylphenoxymethyl) benzene , 4-chlorobenzyloxy-
(4'-ethoxybenzene), 4,4'-bis (phenoxy) diphenyl ether, 4,4'-bis (phenoxy)
Ether compounds such as diphenylthioether, 1,4-bis (4′-benzylphenoxy) benzene, and 1,4-bis [(4′-methylphenyloxy) methoxymethyl] benzene,

For example, 1,4-diglycidyloxybenzene, 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone, 4- (4-methylbenzyloxy) -4'-glycidyloxydiphenylsulfone, Epoxy compounds such as N-glycidyl phthalimide, for example, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5 '
-Tert-butylphenyl) benzotriazole, 2-
(2'-Hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-
tert-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-
tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octyl Examples thereof include triazole compounds such as phenyl) benzotriazole.
It is not limited to these. These heat-fusible compounds may be used alone or in combination.

The heat-sensitive recording material of the present invention can be produced by a commonly used method without any special method. Generally, in the presence of water, an electron-donating color-forming compound, a compound represented by formula (1), and, if desired,
The heat-fusible compound, etc., together or separately, is usually 3 μm by a ball mill, sand mill (vertical type, horizontal type), attritor, colloidal mill, etc., and a pulverizer.
Hereinafter, preferably, the coating liquid for the recording layer can be prepared by pulverizing and dispersing to a particle size of 2 μm or less and mixing.

A binder is usually mixed in the coating solution in an amount of about 5 to 50% by weight based on the total solid content. As the binder, a water-soluble binder is generally used, for example,
Polyvinyl alcohol, carboxy modified polyvinyl alcohol, sulfonation modified polyvinyl alcohol, polyvinyl alcohol derivatives such as alkyl modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and other cellulose derivatives, epichlorohydrin modified polyamide, ethylene-maleic anhydride Polymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyacrylic acid, polyacrylamide, methylol-modified polyacrylamide, starch, starch derivative (oxidized starch, etherified starch, etc.), casein, gelatin , Gum arabic, and the like, but are not limited thereto.

Further, if necessary, a pigment,
A water-insoluble binder, metal soap, wax, surfactant, ultraviolet absorber, ultraviolet stabilizer, crosslinking agent, hindered phenol, phosphorus compound, defoaming agent, etc. are added. As the pigment, for example, calcium carbonate, barium carbonate,
Inorganic pigments such as magnesium carbonate, zinc carbonate, zinc oxide, aluminum oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, talc, wax, kaolin, clay, diatomaceous earth, silica, styrene microballs, nylon particles , Urea-formalin fillers, polyethylene particles, cellulose fillers, starch particles and other organic pigments are used.

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used,
Examples thereof include styrene-butadiene rubber latex, acrylonitrile-butadiene latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion and the like. Examples of the metal soap include metal salts of higher fatty acids such as zinc stearate, calcium stearate, aluminum stearate and zinc oleate. As a wax,
Examples thereof include paraffin wax, microcrystalline wax, carboxy-modified paraffin wax, carnauba wax, polyethylene wax, polystyrene wax, candelia wax, montan wax, and higher fatty acid ester.

As the surfactant (dispersant), for example,
Sulfosuccinic acid-based alkali metal salts [for example, di (n-
Hexyl) sulfosuccinic acid, di (2-ethylhexyl)
Sodium salt of sulfosuccinic acid and the like], sodium salt of dodecylbenzene sulfonic acid, sodium salt of lauryl alcohol sulfate, fatty acid metal salt, fluorine-containing surfactant and the like. Examples of the ultraviolet absorber and the ultraviolet stabilizer include cinnamic acid derivatives, benzophenone derivatives, triazole derivatives, salicylic acid derivatives, hindered amine derivatives and the like. Examples of the cross-linking agent include aldehyde derivatives such as glyoxal,
Examples thereof include epoxy compounds, polyamide resins, diglycidyl compounds, aziridine compounds, magnesium chloride and ferric chloride.

The hindered phenol is preferably a phenol derivative in which at least one of the ortho positions of the phenolic hydroxyl group is substituted with a branched alkyl group.
2,6-diisopropyl-4-methylphenol, 2,
6-di-tert-butyl-4-methylphenol, 2-te
rt-Butyl-4-methoxyphenol, 2,5-di-te
rt-octyl-4-methoxyphenol, 2,5-di-
tert-butylhydroquinone, 2,5-di-tert-octylhydroquinone, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2 -Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-
Tris (2-ethyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (3,5-di-tert-butyl-4-hydroxyphenyl) butane,
1,1,3-tris (2-methyl-4-hydroxy-5)
-Tert-butylphenyl) propane, 1,1-bis (2
-Methyl-5-tert-butyl-4-hydroxy) butane, tetrakis [methylene-3- (3 ', 5'-di-tert-
Butyl-4'-hydroxyphenyl) propionate] methane, 2,2'-methylene-bis (6-tert-butyl-4)
-Methylphenol), 2,2'-methylene-bis (6-
tert-butyl-4-ethylphenol), 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-tert-
Butyl-4-hydroxybenzyl) benzene, 1,3
5-tris (4-tert-butyl-3-hydroxy-2,
6-Dimethylbenzyl) isocyanuric acid, 1,3,5-
Tris (4-tert-butyl-3-hydroxy-2-methyl-6-ethylbenzyl) isocyanuric acid, bis (2-
Methyl-4-hydroxy-5-tert-butylphenyl)
Examples thereof include sulfide.

As the phosphorus compound, a phosphate compound is preferable, and for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenyl) phosphate, 2,2'-methylenebis (4-methyl-6-tert-butylphenyl) phosphate,
2'-methylenebis (4-ethyl-6-tert-butylphenyl) phosphate, 2,2'-methylenebis (4,6-
Di-tert-butylphenyl) phosphate, diphenylphosphate, bis (4-tert-butylphenyl) phosphate, bis (2,4-ditert-butylphenyl)
Phosphate, bis (4-chlorophenyl) phosphate, bis (2-phenylphenyl) phosphate, bis (4-phenylphenyl) phosphate, etc., or a metal thereof (for example, potassium, sodium, zinc,
Calcium, magnesium, aluminum) salts can be mentioned.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally known technique. For example, the coating liquid for the heat-sensitive recording layer is coated on a support with an appropriate coating device such as an air knife coater, a blade coater, a bar coater, a short dwell coater, a gravure coater, a curtain coater, and a wire bar, and dried. Can form a recording layer. The coating amount of the coating liquid is not particularly limited, but it is generally about 1.5 to 12 g / m ^{2 in} dry weight, preferably 2.5.
It is adjusted at about 10 g / m ² . The support is not particularly limited, but, for example, paper, plastic sheet, synthetic paper, or a composite sheet or a non-woven sheet in which these are combined, a molded product, or a metal deposition product is used.

If necessary, a protective layer (overcoat layer) may be provided on the front surface and / or the back surface of the heat-sensitive recording layer, or a single-layer or a plurality of layers of pigment (for example, between the support and the heat-sensitive recording layer). Providing an undercoat layer (undercoat layer) made of kaolin, calcium carbonate) or synthetic resin (for example, plastic spherical particles, plastic spherical hollow particles), between the heat-sensitive recording layer and the undercoat layer,
Alternatively, it is of course possible to provide an intermediate layer composed of a pigment, a binder, etc. between the heat-sensitive recording layer and the protective layer, and further, the back surface of the support is subjected to an adhesive treatment to form an adhesive label. Various known techniques in the manufacturing method of can be applied. Further, after forming the heat-sensitive recording layer and / or the protective layer, super calendering treatment can be performed.

[0037]

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. In the examples,% represents% by weight. [Preparation Method of Dispersion Liquid for Thermosensitive Recording Paper] A having the composition shown below,
The liquids B and C were dispersed by a sand grinding mill so that the average particle diameter was 1.5 μm, to prepare a dispersion liquid. (Liquid A composition) Electron-donating color forming compound 10 g 10% polyvinyl alcohol aqueous solution (Kuraray-117) 10 g Water 80 g Total 100 g (Liquid B composition) Electron-accepting compound 20 g Light calcium carbonate (Okutama industry, TP-123) 40 g 10 % Polyvinyl alcohol aqueous solution (Kuraray-117) 60 g Water 130 g Total 250 g (C liquid composition) Thermofusible compound (2-benzyloxynaphthalene) 20 g 10% Polyvinyl alcohol aqueous solution (Kuraray-117) 10 g Water 220 g Total 250 g

Examples 1 to 4 Dispersion liquids of 100 g of solution A, 250 g of solution B and 250 g of solution C were mixed with 23 g of 30% paraffin wax, and the mixture was applied to a high-quality paper at a dry coating amount of 5 g / m 2. ^It was coated so as to be ² and dried to prepare a thermal recording paper. The electron-donating color-forming compound and the electron-accepting compound used in each example are shown in Table 1 (Table 1). The obtained thermal recording paper was evaluated by the following evaluation methods, and the results are shown in Table 2 (Table 2) and Table 3 (Table 3).

[0039]

[Table 1]

Comparative Examples 1 and 2 23 g of 30% paraffin wax was mixed with each dispersion of 100 g of solution A, 250 g of solution B and 250 g of solution C, and the dry coating amount was 5 g / A thermal recording paper was prepared by coating and drying so as to give m ² . Incidentally, as the electron-donating color forming compound in the liquid A, in Comparative Examples 1 and 2, 3-di-n-butylamino-6-methyl-7-
Anilino fluoran was used. As the electron-accepting compound in the liquid B, bisphenol A was used in Comparative Example 1, and 4-hydroxybenzoic acid benzyl ester was used in Comparative Example 2. The obtained thermal recording paper was evaluated by the following evaluation methods, and the results are shown in Table 2 (Table 2) and Table 3 (Table 3).

[Evaluation Method of Thermosensitive Recording Paper] (Storage Stability Test of Uncolored Part) With respect to each thermal recording paper prepared in Examples and Comparative Examples, the whiteness of the uncolored part (background) immediately after application was determined by color difference. It was measured using a meter (Σ-80, manufactured by Nippon Denshoku). As the storage stability test, a moist heat resistance test, an oil resistance test, and a writing instrument test were conducted, and the whiteness of the uncolored portion of each thermosensitive recording paper after each test was examined. In the moist heat resistance test, each thermosensitive recording paper was stored at 60 ° C. and 90% relative humidity for 24 hours, and the whiteness thereof was measured using a color difference meter. -For the oil resistance test, each thermosensitive recording paper was overlaid with a capsule coating paper containing dioctyl phthalate, passed through a pressure roll, and stored for 1 week at 25 ° C using a color difference meter to measure the whiteness. It was measured. The larger the value, the higher the whiteness and the better the storage stability of the uncolored part. In the writing instrument test, the uncolored portion was written with a highlighter pen, and then the whiteness after standing at 25 ° C. for 72 hours was visually observed. ⊚ indicates a state in which there is no stain and high whiteness, and x indicates a state in which it is stained in black gray. The results are shown in Table 2 (Table 2).

(Colored Image Storage Stability Test) Each of the thermosensitive recording papers prepared in Examples and Comparative Examples was subjected to a Macbeth densitometer (TR-524 type) using a thermosensitive paper coloring device (TH-PMD manufactured by Okura Electric Co., Ltd.). ), The color density measured is 0.9.
After forming a color image having the following formula, a storage stability test was conducted. As the storage stability test, a moist heat resistance test, an oil resistance test, and a writing instrument test were conducted to examine the image storage stability of each thermal recording paper after each test. In the moist heat resistance test, each of the thermosensitive recording papers was stored at 60 ° C. and 90% relative humidity for 24 hours, the color image density was measured using a Macbeth densitometer, and the residual ratio of the color image was obtained.・ The oil resistance test was carried out by stacking capsule coating paper containing dioctyl phthalate on each thermosensitive recording paper, passing it through a pressure roll, and then storing it at 25 ° C. for 1 week. Was used to determine the residual rate of the color image. The residual rate was calculated by the following formula. The higher the number,
It shows that the storage stability of the color image is excellent. As a writing resistance test, after writing the colored image with a highlighter pen, the degree of residual of the colored image was visually observed after leaving at 25 ° C. for 72 hours. ◎ indicates that there is no decolorization,
X indicates a state of decoloring. The results are shown in Table 3 (Table 3).

[0043]

[Table 2] From the results shown in Table 2, the heat-sensitive recording material of the present invention using the compound represented by the formula (1) as the electron-accepting compound is compared with the heat-sensitive recording material produced using the conventional electron-accepting compound. , It was found that it was extremely excellent in the writing instrument test of the uncolored part.

[0044]

[Table 3] From the results shown in Table 3, the heat-sensitive recording material of the present invention in which the compound represented by the formula (1) is used as an electron-accepting compound is compared with the heat-sensitive recording material prepared using the conventional electron-accepting compound. It was found that the storage stability (moisture and heat resistance, oil resistance and writing instrument resistance) of the color image was extremely excellent.

[0045]

According to the present invention, it has become possible to provide a heat-sensitive recording material which is very excellent in the storage stability of uncolored portions and colored images.

Claims (1)

[Claims] 1. A heat-sensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, wherein the electron-accepting compound contains a compound represented by formula (1) . [Chemical 1]