JPH1148622A - Thermosensible recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thermosensible recording material having the improved oil resistance and plastic resistance of a coloring image by the use of a specific fluorane compound as a coloring agent, and a specific organic phosphorous compound as a developer. SOLUTION: As an achromatic or monochromic electron donative coloring agent, there is employed a fluorane compound expressed by formula I. Herein, R<1> and R<2> respectively represent independently alkyl groups of 1-5C. As an electron acceptive developer capable of coloring in contact with the coloring agent, an organic phosphorous compound is used, which is shown by formula II. R<3> , R<4> independently represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, or an aralkyl group. However, R<3> , R<4> never exist simultaneously as a hydrogen atom or hydroxy group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly, to a heat-sensitive recording material in which a color image has improved oil resistance and plasticizer resistance.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording material is provided on a support such as paper, synthetic paper, plastic film or the like, with an electron-donating color former (hereinafter referred to as a color former) and an organic or inorganic electron-accepting developer (hereinafter referred to as a color developer). , A color developer) as a main component, and a recorded image can be obtained by applying thermal energy. Such heat-sensitive recording materials are disclosed in JP-B-43-4160, JP-B-45-14039 and JP-A-48-27736.
The recording apparatus is widely used because the recording apparatus is compact, inexpensive, and easy to maintain.

[0003] For example, it is used in a wide range of applications such as output of electronic computers, facsimile machines, automatic ticket vending machines, printers for scientific measuring instruments, and printers for CRT medical measurement.

In such heat-sensitive recording materials, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) is widely used as a color developer because of its low cost and good availability. However, the heat-sensitive recording material using bisphenol A has a problem that the storage stability of a color image is low.

[0005] Various attempts have been made to solve this problem. For example, JP-A-56-144193 discloses a method using 4-hydroxybenzoic acid esters as a color developer, and JP-A-57-193388 discloses a method using hydroxybenzophenones as a color developer. JP-A-31-678 discloses methods using aralkyloxyphenols as developers.

However, when 4-hydroxybenzoic acid esters, for example, benzyl 4-hydroxybenzoate, are used as a color developer, there is a disadvantage that the density of a color image decreases with time, and 4-hydroxybenzoic acid ester is not formed on the color image. There is a problem that white crystals of benzyl hydroxybenzoate precipitate and exhibit a whitening phenomenon.

[0007] Hydroxybenzophenones such as 4-
Even when hydroxybenzophenone is used as a color developer, the storage stability of the color image (wet heat resistance and plasticizer resistance)
, And cannot be said to have sufficient performance for practical use.

Also, when aralkyloxyphenols, for example, 4-benzyloxyphenol, are used as a color developer, there is a disadvantage that the color image density decreases with time.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material in which a color image has improved oil resistance and plasticizer resistance.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, at least one fluoran compound represented by the general formula (1) as a color former has been developed. It has been found that the problem can be solved by a heat-sensitive recording material using at least one of the organic phosphorus compounds represented by the general formula (2) as a coloring agent, and the present invention has been completed.

[0011]

Embedded image [Wherein, R ¹ and R ² each independently represent a carbon atom of 1
5 to 5 alkyl groups. ]

[0012]

Embedded image [Wherein, R ³ and R ⁴ independently represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, or an aralkyl group. However, R ³ and R ⁴ are not simultaneously a hydrogen atom or a hydroxy group. ]

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the fluoran compound represented by the general formula (1), R ¹ and R ² are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl. Group, isobutyl group, n-pentyl group and isopentyl group, and among them, those having 2 to 5 carbon atoms are particularly preferable.

A specific example of the fluoran compound represented by the general formula (1) is 2- (3-methylanilino) -3-
Methyl-6-dimethylaminofluoran, 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran, 2- (3-methylanilino) -3-methyl-6
-Di-n-propylaminofluoran, 2- (3-methylanilino) -3-methyl-6-diisopropylaminofluoran, 2- (3-methylanilino) -3-methyl-6-di-n-butylaminofluoran Oran, 2- (3-methylanilino) -3-methyl-6-diisobutylaminofluoran, 2- (3-methylanilino) -3-methyl-6- (N-methyl-N-isobutylamino) fluoran, 2- ( 3-methylanilino) -3-methyl-6-
(N-ethyl-N-propylamino) 2- (3-methylanilino) -3-methyl-6- (N-ethyl-N-isopentylamino) fluoran, 2- (3-methylanilino) -3-methyl-6 -Di-n-pentylaminofluoran and the like.

Particularly preferred are 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran and 2- (3-methylanilino) -3-methyl-6-di-n-butylaminofluoran, especially Cu Diffraction angle (2θ) in powder X-ray diffraction by Kα ray: 7.6 °, 1
2.2 °, 14.9 °, 15.9 °, 17.6 °, 2
Preferred is the β-crystal modification of 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran, characterized by 2.8 °.

The fluoran compound represented by the general formula (1) can be produced, for example, by the following method.

General formula (3)

Embedded image [Wherein, R ¹ and R ² are the same as defined above. A benzophenone compound represented by the general formula (4):

[0018]

Embedded image [Wherein, R represents a hydrogen atom or a lower alkyl group. ]
Is reacted at a temperature of 0 to 50 ° C. for several hours to several tens of hours in the presence of a dehydration condensing agent such as concentrated sulfuric acid, and the resulting reaction product is treated with an aqueous alkali solution such as sodium hydroxide. The fluoran compound represented by the general formula (1) can be obtained in the form of a white to slightly colored powder by performing purification, recrystallization, and the like using an appropriate organic solvent as necessary.

Also, 2- (3-methylanilino) -3-
The β-crystal modification of methyl-6-diethylaminofluoran can be obtained according to the method disclosed in JP-A-6-25249. For example, the benzophenone compound of the general formula (1) is reacted with the diphenylamine compound of the general formula (2) in the presence of a dehydrating condensing agent, and then impurities in the organic solvent extract of the treated product after alkali treatment are extracted. It can be produced by precipitating from an organic solvent extract that is 10% or less of the components.

In the organic phosphorus compound represented by the general formula (2), R ³ and R ⁴ are a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, and an aralkyl group. More specifically, examples thereof include a linear or branched alkyl group having 1 to 20 carbon atoms, an unsubstituted or substituted phenyl group, a naphthyl group, and a benzyl group. Examples of the substituent include a linear or branched alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyl group, an amino group, a cyano group, a carboxyl group, a halogen atom, and the like. .

Specific examples of R ³ and R ⁴ include a hydrogen atom,
Hydroxy group, methyl group as an alkyl group, ethyl group,
Chloroethyl, aminoethyl, hydroxyethyl, propyl, isopropyl, butyl, aminobutyl, t-butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, aryl, etc. Phenyl group, hydroxyphenyl group, methylphenyl group, methoxyphenyl group, ethoxyphenyl group, 4-t-butylphenyl, chlorophenyl group, aminophenyl group, naphthyl group and the like as groups, benzyl group, methylbenzyl group as aralkyl group, And a phenethyl group.

As the organic phosphorus compound represented by the general formula (2), specifically, methylphosphonic acid, aminomethylphosphonic acid, ethylphosphonic acid, 1-aminoethylphosphonic acid, 2-aminoethylphosphonic acid, 2-aminoethylphosphonic acid, Chloroethylphosphonic acid, propylphosphonic acid, 3-aminopropylphosphonic acid, butylphosphonic acid, t-butylphosphonic acid, hexylphosphonic acid, cyclohexylphosphonic acid,
Octylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, pentadecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, docosylphosphonic acid,
Isohexylphosphonic acid, 1-hexenylphosphonic acid,
Iso-1-pentynylphosphonic acid, phenylphosphonic acid, 4-aminophenylphosphonic acid, 1-naphthylphosphonic acid, 4-t-butylphenylphosphonic acid, 2-chlorophenylphosphonic acid, 4- (β-hydroxyethyl)
Examples include phenylphosphonic acid, 4-butoxyphenylphosphonic acid, 4-dodecylphenylphosphonic acid, dimethylphosphinic acid, phenylphosphonous acid, diphenylphosphinic acid, and bis (4-methoxyphenyl) phosphinic acid.

In the present invention, other color formers can be used together with the fluoran compound of the formula (1) as long as the effect is not impaired. As the color former that can be used in combination, any of those conventionally used for this type of recording material can be used. In particular, fluoran, diaryl phthalide, indolyl phthalide, vinylog phthalide, azaphthalide, thiazine, spiropyran,
Color formers such as fluorenes are preferred.

Examples of some of these are fluoran compounds such as 3,6-dimethoxyfluoran,
Chloro-6-cyclohexylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 3-methyl-6-cyclohexylaminofluoran, 1,3-dimethyl-6 Diethylaminofluoran, 2-tert-
Butyl-6-diethylaminofluoran, 2-chloro-
6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-methyl-6
(N-ethyl-4-methylanilino) fluoran, 8-
Diethylaminobenzo [a] fluoran, 2-dibenzylamino-6-diethylaminofluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-n-octylamino-6-diethylaminofluoran, 2- Anilino-6- (N-ethyl-NNn-hexylamino) fluoran, 2- (N-methylanilino) -6- (N-ethyl-4-methylanilino) fluoran, 2-chloro-3-methyl-6- [ 4- (4-anilinoanilino) anilino] fluoran, 2-anilino-
3-methyl-6-dimethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2
-Anilino-3-methyl-6-di-n-propylaminofluoran,

2-anilino-3-methyl-6-di-n-
Butylaminofluoran, 2-anilino-3-methyl-
6-di-n-pentylaminofluoran, 2-anilino-3-methyl-6- (N-methyl-N-ethylamino)
Fluoran, 2-anilino-3-methyl-6- (N-methyl-NN-propylamino) fluoran, 2-anilino-3-methyl-6- (N-methyl-N-n-butylamino) fluoran, 2-anilino-3-methyl-6
(N-methyl-N-isobutylamino) fluoran, 2
-Anilino-3-methyl-6- (N-methyl-Nn-
(Pentylamino) fluoran, 2-anilino-3-methyl-6- (N-methyl-N-cyclohexylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-N-n-propylamino) fluoran , 2-anilino-3-methyl-6- (N-ethyl-NN-butylamino) fluoran, 2-anilino-3-methyl-6
(N-ethyl-N-isobutylamino) fluoran, 2
-Anilino-3-methyl-6- (N-ethyl-N-n-
(Pentylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-N-isopentylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-Nn-octylamino) Fluoran, 2-anilino-3-methyl-6- [N-ethyl-N- (3-ethoxypropyl) amino] fluoran, 2-anilino-3-methyl-6- (N-ethyl-N-p-tolylamino) Fluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-anilino-3-chloro-6-di-n
-Butylaminofluoran,

2- (2-chloroanilino) -6-diethylaminofluoran, 2- (2-chloroanilino) -6
-Di-n-butylaminofluoran, 2- (2-fluoroanilino) -6-diethylaminofluoran, 2-
(2-fluoroanilino) -6-di-n-butylaminofluoran, 2- (3-trifluoromethylanilino)
-6-dimethylaminofluoran, 2- (3-trifluoromethylanilino) -6-diethylaminofluoran, 2- (3-trifluoromethylanilino) -6-di-n-butylaminofluoran, 2 -(4-methylanilino) -3-methyl-6-diethylaminofluoran,
2- (4-t-amylanilino) -3-methyl-6-diethylaminofluoran, 2- (3-chloro-4-methylanilino) -3-methyl-6-diethylaminofluoran, 2- (2,4-dimethyl Anilino) -3-methyl-6-diethylaminofluoran, 2- (2,4-dimethylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (2,6-dimethylani Reno) -3
-Methyl-6-diethylaminofluoran, 2- (2,
6-dimethylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (2,6-diethylanilino) -3-methyl-6-diethylaminofluoran, 2
-(2,6-diethylanilino) -3-methyl-6-di-n-butylaminofluoran, 2-anilino-3-methoxy-6-diethylaminofluoran, 2,2-bis {4- [6 -(N-cyclohexyl-N-methylamino) -3-methylfluoran-2-ylamino] phenyl} propane and the like,

As the diarylphthalide compound,
3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (general name: CVL), 3,3-bis (4-dimethylaminophenyl) phthalide, 3- (4-
Dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrole-3-
Yl) -6-dimethylaminophthalide and the like,

As the indolylphthalide compound, 3
-(4-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (1-ethyl-2-
Methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl-2-methylindol-3-yl)
Phthalide, 3,3-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindole- 3-yl) phthalide, 3-
(2-ethoxy-4-dibutylaminophenyl) -3-
(1-ethyl-2-methylindole-3-yl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindole-3
-Yl) phthalide, etc.

As vinylogous phthalide compounds, 3
-(4-Diethylaminophenyl) -3- [2,2-bis (1-ethyl-2-methylindol-3-yl) ethenyl] phthalide, 3,3-bis [2- (4-dimethylaminophenyl)- 2- (4-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, 3,
3-bis [2- (4-pyrrolidinophenyl) -2- (4
-Methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [2,2-bis (4
-Dimethylaminophenyl) ethenyl] -4,5,6
7-tetrachlorophthalide, 3,3-bis [2,2-bis (4-pyrrolidinophenyl) ethenyl] -4,5
6,7-tetrabromophthalide and the like,

As the azaphthalide compound, 3,3-
Bis (4-diethylamino-2-ethoxyphenyl)-
4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- [4- (N-ethyl-N-phenylamino) -2-ethoxyphenyl] -4-azaphthalide, 3- (4-diethylamino- 2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-
Yl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-n-octyl-
2-Methylindol-3-yl) -4-azaphthalide and the like include 4,4′-
Bis (dimethylamino) benzhydryl benzyl ether, N-halophenylleuco auramine and the like, as rhodamine lactam compounds, rhodamine B anilinolactam, rhodamine B (4-nitroanilino) lactam, rhodamine B (4-chloroanilino) Lactam etc.

Examples of the thiazine compound include benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, and examples of the spiropyran compound include 3-
Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3-phenylspirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirodinaphthopyran and the like,

Examples of the fluorene compound include 3,6-bis (dimethylamino) fluorenespiro [9,3 ']-
6'-dimethylaminophthalide, 3-diethylamino-
6- (N-allyl-N-methylamino) fluorenespiro [9,3 ′]-6′-dimethylaminophthalide, 3,
6-bis (dimethylamino) spiro [fluorene-9,
6′-6′H-chromeno (4,3-b) indole],
3,6-bis (dimethylamino) -3′-methylspiro [fluorene-9,6′-6′H-chromeno (4,3-
b) Indole], 3,6-bis (diethylamino)-
3'-methylspiro [fluorene-9,6'-6'H-
Chromeno (4,3-b) indole] and the like.
These may be used alone or as a mixture of two or more.

As with the color former, the developer is also
Other developers may be used in combination with the organic phosphorus compound of the formula (2) as long as the effects of the present invention are not impaired, and additives and fillers may be added.

Examples of the developer which can be used in combination include phenol derivatives, organic acids or metal salts / complexes, urea derivatives and the like.

To illustrate some of these, as phenol derivatives, 4-tert-butylphenol, 4-octylphenol, 4-phenylphenol, 1-naphthol, 2-naphthol, hydroquinone, resorcinol, 4-tert-octylcatechol, 2,2'-
Dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 2,2-bis (4-hydroxyphenyl) propane [generic name bisphenol A], tetrabromobisphenol A, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2, 2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (2
-Methyl-4-hydroxy-5-tert-butylphenyl) butane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,4-bis (4-hydroxycumyl) benzene, 1,3 , 5-Tris (4-hydroxycumyl) benzene, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl)
Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane,

4,4 '-(m-phenylenediisopropylidene) bisphenol, 4,4'-(p-phenylenediisopropylidene) bisphenol, bis (4-hydroxyphenyl) acetic acid ethyl ester, 4,4-bis ( 4-hydroxyphenyl) valeric acid-n-butyl ester, 4-hydroxybenzoic acid benzyl ester,
4-hydroxybenzoic acid phenethyl ester, 2,4-
Dihydroxybenzoic acid-2-phenoxyethyl 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 [generic name bisphenol S],
Tetrabromobisphenol S, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 1,
7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane and the like,

As the organic carboxylic acid or its metal salt / complex, salicylic acid, 3-isopropylsalicylic acid,
-Tert-butylsalicylic acid, 3-benzylsalicylic acid,
3-chloro-5- (α-methylbenzyl) salicylic acid,
3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, 3,5-bis- (α-methylbenzyl) salicylic acid, 4- (3-p-toluenesulfonylpropyloxy) salicylic acid, 5- {4- [ 2- (4-methoxyphenoxy) ethoxy] cumyl salicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-α-methylbenzylsalicylic acid, 4- [2- (4- Methoxyphenoxy) ethoxy]
Salicylic acid, 2-hydroxy-3-naphthoic acid, 2-hydroxy-6-naphthoic acid, monobenzyl phthalate, monophenyl phthalate, 4-nitrobenzoic acid, 3-nitrobenzoic acid, 2-nitrobenzoic acid, 4-
Organic acids such as chlorobenzoic acid or metal salts thereof (for example, metal salts such as nickel, zinc, aluminum and calcium), zinc thiocyanate antipyrine complex,
Molybdate acetylacetone complex and the like are used as urea derivatives as phenylthiouric acid, N, N'-diphenylthiourea, N, N'-bis (3-trifluoromethylphenyl) thiourea, 1,4-bis (3-chlorophenyl) Thiosemicarbazide and the like.

These can be used alone or in combination of two or more.

Various heat-fusible substances can be used as the sensitizer. Examples of these acid amide compounds include, as acid amide compounds, caproic amide, capric amide, stearic amide, palmitic amide, oleic amide, stearyl uric acid, stearic anilide, etc., as fatty acids or metal salts thereof. stearic acid,
Behenic acid, fatty acids such as palmitic acid or their zinc, aluminum, calcium salts and the like,

As ester compounds, benzyl 4-benzyloxybenzoate, phenyl 2-naphthoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, bis (4-oxalate)
Methyl benzyl) ester, bis (4-chlorobenzyl) oxalate, diphenacyl glutarate, bis (4-methylphenyl) carbonate, dibenzyl terephthalate, etc., as hydrocarbon compounds such as 4-benzylbiphenyl, m-terphenyl, fluorene, fluoranthene, 2,6-diisopropylnaphthalene, 3-benzylacenaphthene and the like,

As ether compounds, 2-benzyloxynaphthalene, 2- (4-methylbenzyloxy) naphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, , 2-bis (3-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, 4- (4
-Methylphenoxy) biphenyl, 1,4-bis (2-
Chlorobenzyloxy) benzene, 4,4'-di-n-
Butoxydiphenylsulfone, 1,2-diphenoxybenzene, 1,4-bis (2-chlorophenoxy) benzene, 1,4-bis (4-methylphenoxy) benzene, 1,4-bis (3-methylphenoxymethyl) Benzene, 1- (4-chlorobenzyloxy) -4-ethoxybenzene, 4,4'-diphenoxydiphenyl ether, 1,4-bis (4-benzylphenoxy) benzene, 1,4-bis (4-methylphenoxymethoxy) Methyl) benzene and the like. These can be used alone or in combination of two or more.

Particularly, 4-benzylbiphenyl, m-terphenyl, 2-benzyloxynaphthalene, bis (4-methylbenzyl) oxalate, and 1,2-bis (3-methylphenoxy) ethane are preferably used.

As the support, paper, coated paper, synthetic paper,
A plastic film or the like is used.

Examples of the water-soluble binder include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, isobutylene-maleic anhydride copolymer. Polymer hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide and the like are used.

As the pigment, organic and inorganic pigments can be used. Preferred specific examples include calcium carbonate,
Examples include barium sulfate, titanium oxide, aluminum hydroxide, amorphous silica, urea formalin resin powder, polyethylene resin powder, and the like.

As the water-insoluble binder, styrene-
Butadiene rubber latex, acrylonitrile-butadiene rubber latex, vinyl acetate emulsion and the like are used as needed.

As the antisticking agent, stearic acid, carnauba wax, paraffin wax, carboxy-modified wax, polyethylene wax, zinc stearate, calcium stearate, aluminum stearate and the like are used.

Examples of the anti-adhesion agent include inorganic pigments such as kaolin, clay, talc, calcium carbonate, titanium oxide, and silica; and organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea, formalin resin filler, and starch. Used.

Examples of the ultraviolet absorber include benzophenone and its derivatives, benzotriazole and its derivatives, benzoin and its derivatives, 2-chloroanthraquinone,
Benzyl peroxide, salicylates such as pt-butylphenyl salicylate, and cyanoacrylates such as ethyl diphenylacrylate can be used.

As antioxidants, 2,6-di-tert-butyl-4-methylphenol, di (3-tert-butyl-4)
-Hydroxy-5-methylphenyl) thioether,
1,1-bis (2-methyl-4-hydroxy-5-t-
Hindered phenols such as butylphenyl) butane; di (2,2,6,6-tetramethyl-4 sebacate)
Hindered amines such as (piperidine).

As the pigment, inorganic and inorganic pigments can be used. Preferred specific examples include calcium carbonate,
Examples include zinc oxide, titanium oxide, zinc hydroxide, aluminum hydroxide, amorphous silica, calcined clay, talc, urea formalin resin, polyethylene resin, polystyrene resin, and styrene / methacrylic acid polymer.

The heat-sensitive recording material of the present invention is produced, for example, according to the following method.

A color former, a developer and a sensitizer are dispersed together with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol by using an attritor, a sand mill or the like so that the particle diameter of the drug becomes several microns or less. The sensitizer may be dispersed simultaneously with one or both of the color former and the developer, or in some cases, a eutectic with the color former or the developer may be prepared and dispersed in advance. Is also good. These dispersions are mixed, and if necessary, pigments, binders, waxes, metal soaps, antioxidants, ultraviolet absorbers and the like are added to obtain a heat-sensitive coating liquid.

Mixing ratio (weight ratio) of color former and developer
Is from 0.5 to 3 times, preferably from 1 to 2.5 times, the color developer to the color former 1.

The obtained heat-sensitive coating liquid is applied to a support such as high quality paper, synthetic paper, plastic film and the like, dried and then smoothed by calendering to obtain a heat-sensitive recording material. In addition, the heat-sensitive coating liquid may be applied to a support having a heat insulating layer such as a plastic pigment or silica, as needed, in order to improve the color development. Further, in order to impart water resistance and chemical resistance, an overcoat layer such as a water-soluble polymer may be provided on the heat-sensitive recording layer as needed.

[0056]

The present invention will be described more specifically with reference to the following examples.

Example 1 Preparation of Coloring Agent Dispersion 3 g of β-crystal modification of 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran was placed in 70 g of a 2% aqueous solution of polyvinyl alcohol using a sand mill. Then, the resulting mixture was pulverized so that the average particle size became 1 μm to obtain a color former dispersion.

Preparation of Developer Dispersion 6 g of phenylphosphonic acid and 3 g of sensitizer p-benzylbiphenyl were added to 75 g of a 2% aqueous solution of polyvinyl alcohol.
The resulting mixture was pulverized using a sand mill so that the average particle size became 3 μm, to obtain a developer dispersion.

Preparation of Thermosensitive Coating Liquid After the above color former dispersion and developer dispersion were mixed in total, 15 g of calcium carbonate was dispersed in 50 ml of water and 15 g of a 30% paraffin wax dispersion were added. Then, the mixture was mixed well to obtain a heat-sensitive coating liquid.

[0060]Preparation of thermal recording material  The obtained heat-sensitive coating liquid is coated on a high quality paper at a solid content of about 5 g /
m, dried and then calendered
The Bekk smoothness of the surface of the heat-sensitive recording layer should be about 300 seconds.
And a thermosensitive recording material was obtained.

(Example 2) In place of the β-form modification of 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran which is a color former in Example 1,
A heat-sensitive recording material was produced in the same manner as in Example 1, except that (3-methylanilino) -3-methyl-6-di-n-butylaminofluoran was used.

(Comparative Example 1) Instead of phenylphosphonic acid which is a developer in Example 1, 2,2-bis (4-
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that (hydroxyphenyl) propane was used.

(Comparative Example 2) Instead of the β-form modification of 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran which is a color former in Example 1,
A heat-sensitive recording material was prepared in the same manner as in Example 1, except that anilino-3-methyl-6- (N-ethyl-N-isopentylamino) fluoran was used.

(Evaluation) Examples 1 and 2 and Comparative Examples 1 and 2
A reflection densitometer RD-91
4 (manufactured by Macbeth) to measure background whiteness. Next, using a printing apparatus TH-PMD (manufactured by Okura Electric Co., Ltd.), a color image was obtained by adjusting the pulse width so that the color image density (OD value) was about 1.1. The color images were subjected to the oil resistance and plasticizer resistance tests described below, and the stability of the color images was evaluated by the residual ratio. Table 1 shows the results.

Residual rate (%) = (color image density after test / color image density before test) × 100 The lower the background whiteness, the higher the whiteness, and the higher the residual rate, the higher the whiteness. The higher the stability, the higher the stability of the color image.

Oil resistance test A salad oil was applied to the color image, excess salad oil was wiped off, and after standing at room temperature for 3 hours, a reflection densitometer RD-91 was used.
In step 4, the residual image density was measured.

Test for Plasticizer Resistance Dioctyl phthalate was applied to the color-developed image, excess was wiped off, left at room temperature for 3 hours, and the residual image density was measured with a reflection densitometer RD-914.

[0068]

[Table 1] Background whiteness and storage stability of color image ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Background whiteness before test Colored image Residual rate (%) ────────── (OD value) Concentration (OD value) Oil resistance Plasticizer resistance ━━━━━━━━━━━━━━━━━━ {Example 1 0.09 1.10 98 85 Example 2 0.08 1.10 97 84} Comparative Example 1 0.07 1.11 27 15 Comparative Example 2 0.11 1.10 89 79 ━━━━━━━━━━━━━━━━

[0069]

According to the present invention, as is apparent from Table 1,
A heat-sensitive recording material having improved oil resistance and plasticizer resistance of a color image can be provided.

Claims (3)

[Claims] 1. A thermosensitive recording material utilizing a color reaction between a colorless or light-colored electron-donating color former and an electron-accepting color developer capable of forming a color upon contact with said color-developing agent. The following general formula (1) [Wherein, R ¹ and R ² each independently represent a carbon atom of 1
5 to 5 alkyl groups. And at least one fluoran compound represented by the following general formula (2): [Wherein, R ³ and R ⁴ independently represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, or an aralkyl group. However, R ³ and R ⁴ are not simultaneously a hydrogen atom or a hydroxy group. ] At least one kind of the organic phosphorus compound represented by formula (1) is used. 2. The method according to claim 1, wherein the electron-donating color former is 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran or 2- (3-methylanilino) -3-methyl-6.
2. The heat-sensitive recording material according to claim 1, which is -di-n-butylaminofluoran. 3. 2- (3-methylanilino) -3-methyl-6-diethylaminofluoran has a diffraction angle (2θ) of 7.6 ° in a powder X-ray diffraction method using Cu-Kα ray,
12.2 °, 14.9 °, 15.9 °, 17.6 °, 2
3. The heat-sensitive recording material according to claim 2, which is a β-form crystal modification characterized by an X-ray diffraction pattern showing a characteristic peak at 2.8 °.