JP3300074B2 - Thermal recording material - Google Patents

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 having improved storage stability of a color image.

[0002]

2. Description of the Related Art Heat-sensitive recording materials utilizing a color reaction between an electron-donating color-forming compound and an electron-accepting compound (a color developer) have been well known (for example, Japanese Patent Publication No. 43-41).
No. 60, JP-B-45-14039). Thermosensitive recording materials are widely used in the fields of facsimile machines, recorders, and printers because of their advantages of being relatively inexpensive and having compact and maintenance-free recording equipment.

Hitherto, phenolic compounds have been widely used as electron-accepting compounds.
Bis (4'-hydroxyphenyl) propane (also known as bisphenol A) is widely used in that it is easily available at a low price. However, heat-sensitive recording materials using bisphenol A as an electron-accepting compound produce color. There is a problem that image storage stability is poor. Further, the heat-sensitive recording material using bisphenol A as an electron-accepting compound also has a problem that the coloring sensitivity is low. Examples of phenolic compounds other than bisphenol A include 4-hydroxybenzoic acid esters (JP-A-56-144193, JP-B-1-30640) and aralkyloxyphenols (JP-B-2-31678). , JP 6
Thermal recording materials using hydroxybenzophenones (JP-A-57-193388) as electron-accepting compounds have been proposed.

However, when 4-hydroxybenzoic esters, for example, benzyl 4-hydroxybenzoate, are used as the electron-accepting compound, there is a drawback that the density of the color image decreases with the passage of time. -There is a problem that white crystals of benzyl hydroxybenzoate are precipitated and exhibit a powdered state (so-called whitening phenomenon). The use of aralkyloxyphenols, for example, 4-benzyloxyphenol, as the electron-accepting compound also has the disadvantage that the color image density decreases over time. When hydroxybenzophenones, for example, 4-hydroxybenzophenone, are used as the electron-accepting compound, the storage stability (for example, wet heat resistance and water resistance) of the color image is poor, and it has sufficient performance for practical use. I can't say that.

[0005] Further, as a method of improving the coloring sensitivity,
In addition to the electron-donating color-forming compound and the electron-accepting compound, heat-sensitive recording materials further containing a heat-fusible compound (sensitizer) are widely used. Examples of the heat-fusible compound include terphenyls (JP-B-63-7958), benzyl 4-benzyloxybenzoate (JP-B-63-30878), naphthol derivatives (JP-B-63-42590), amino Phenol derivatives (Japanese Unexamined Patent Publication No.
494), benzyl biphenyls (JP-B 2-1)
No. 1437), diaryloxyalkane derivatives (JP-A-60-56588, JP-A-61-168).
No. 88) or an oxalate derivative (JP-A-1-1583). However, heat-sensitive recording materials containing these heat-fusible compounds, although having improved color-forming sensitivity to some extent, have extremely poor storage stability of color-formed images, and usually develop colors compared to the case where no heat-fusible compounds are added. Actually, there is a problem that the storage stability of the image is further inferior.

At present, there is a strong demand for a heat-sensitive recording material which overcomes the above problems and has excellent storage stability of a color image.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material in which the storage stability of a color image is remarkably improved.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on a heat-sensitive recording material in order to meet the above-mentioned demands, and have reached the present invention.

That is, the present invention relates to a heat-sensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, which has a general formula (1)

[0010]

Embedded image (Wherein, R is an alkyl group having 1 to 20 carbon atoms, 6 to
20 aryl groups, aryloxy having 6 to 20 carbon atoms
Group, aralkyloxy group having 7 to 20 carbon atoms, halogen atom
The alkoxy component is monosubstituted or polysubstituted
A good alkoxyalkyl group having 2 to 24 carbon atoms , or
Total aryloxyalkyl group having 7 to 24 carbon atoms and table,
The aryl group contained in R is an alkyl group having 1 to 6 carbon atoms.
Group, an alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 7 to 10 carbon atoms
An aralkyl group, an aralkyloxy group having 7 to 10 carbon atoms,
Mono-substituted with toro, formyl, halogen and cyano groups
Alternatively, it may be polysubstituted. The present invention is a heat-sensitive recording material containing at least one polyvalent metal salt selected from zinc salts and calcium salts of a benzoic acid derivative represented by the following formula:

In the compound represented by the general formula (1) according to the present invention, R is an alkoxyalkyl group having a total of 2 to 24 carbon atoms or an aryloxyalkyl group having a total of 7 to 24 carbon atoms; The component may have a substituent. Examples of the substituent of the alkoxy component include an alkoxy group having 1 to 20 carbon atoms and 6 carbon atoms.
And aryloxy groups having 6 to 20 carbon atoms, aralkyloxy groups having 7 to 20 carbon atoms, halogen atoms, and the like, and these substituents may be monosubstituted or polysubstituted.

The aryl group contained in R in the general formula (1) is an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 6 carbon atoms.
It may be monosubstituted or polysubstituted with a substituent such as an alkoxy group having 6 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an aralkyloxy group having 7 to 10 carbon atoms, a nitro group, a formyl group, a halogen atom, and a cyano group. .

More preferably, R is an alkoxyalkyl group having 2 to 24 carbon atoms which may have a substituent, an alkoxyalkoxyalkyl group having 3 to 24 carbon atoms which may have a substituent, An aralkyloxyalkyl group having 8 to 24 carbon atoms which may have, an aralkyloxyalkoxyalkyl group having 9 to 24 carbon atoms which may have a substituent,
An aryloxyalkyl group having a total of 7 to 24 carbon atoms and an aryloxyalkoxyalkyl group having a carbon number of 8 to 24 which may have a substituent.

Specific examples of R include, for example, methoxymethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-n-propoxyethyl, 2-isopropoxyethyl, 2-n-butoxyethyl , 2-isobutoxyethyl group, 2-n-pentyloxyethyl group, 2-n
-Hexyloxyethyl group, 2-n-heptyloxyethyl group, 2-n-octyloxyethyl group, 2- (2 ′
-Ethylhexyloxy) ethyl group, 2-n-decyloxyethyl group, 2-n-dodecyloxyethyl group, 2-
Cyclopentyloxyethyl group, 2-cyclohexyloxyethyl group, 2-cycloheptyloxyethyl group, 2
-Cyclooctyloxyethyl group, 3-methoxypropyl group, 3-ethoxypropyl group, 3-n-propoxypropyl group, 3-isopropoxypropyl group, 3-n-butoxypropyl group, 3-isobutoxypropyl group, 3 −
n-pentyloxypropyl group, 3-n-hexyloxypropyl group, 3-n-heptyloxypropyl group, 3
-N-octyloxypropyl group, 3- (2'-ethylhexyloxy) propyl group, 3-n-decyloxypropyl group, 3-n-dodecyloxypropyl group, 3-cyclopentyloxypropyl group, 3-cyclohexyloxypropyl Group, 3-cycloheptyloxypropyl group, 3-cyclooctyloxypropyl group, 4-methoxybutyl group, 5-ethoxypentyl group, 6-methoxyhexyl group, 2- (2′-methoxyethoxy) ethyl group,
2- (2′-ethoxyethoxy) ethyl group, 2- (2 ′
-N-butoxyethoxy) ethyl group, 2- (2'-n-
Octyloxyethoxy) ethyl group, 2- (2′-cyclohexyloxyethoxy) ethyl group, 3- (3′-methoxypropoxy) propyl group, 3- (3′-n-hexyloxypropoxy) propyl group, 3- ( 3'-cyclohexyloxypropoxy) propyl group, 2-benzyloxyethyl group, 2- (4'-methylbenzyloxy) ethyl group, 2- (4'-chlorobenzyloxy) ethyl group, 2- (4'-methoxy) Benzyloxy) ethyl group, 3-benzyloxypropyl group, 2- (2′-benzyloxyethoxy) ethyl group, 3- (3′-benzyloxypropoxy) propyl group, phenoxymethyl group,
2-phenoxyethyl group, 2- (4′-methylphenoxy) ethyl group, 2- (3′-methylphenoxy) ethyl group, 2- (2′-methylphenoxy) ethyl group, 2-
(4′-methoxyphenoxy) ethyl group, 2- (3′-
Methoxyphenoxy) ethyl group, 2- (2′-methoxyphenoxy) ethyl group, 2- (4′-benzylphenoxy) ethyl group, 2- (4′-benzyloxyphenoxy) ethyl group, 2- (4′-chloro Phenoxy) ethyl group, 2- (3′-chlorophenoxy) ethyl group, 2-
(2′-chlorophenoxy) ethyl group, 2- (4′-nitrophenoxy) ethyl group, 2- (3′-nitrophenoxy) ethyl group, 2- (2′-nitrophenoxy) ethyl group, 2- (4 '-Formylphenoxy) ethyl group, 2
-(3'-formylphenoxy) ethyl group, 2- (2 '
-Formylphenoxy) ethyl group, 2- (4'-cyanophenoxy) ethyl group, 2- (3'-cyanophenoxy) ethyl group, 2- (2'-cyanophenoxy) ethyl group, 2- (2'-phenoxy) Ethoxy) ethyl group, 2-
[2 '-(4 "-methylphenoxy) ethoxy] ethyl group, 2- [2'-(2" -methylphenoxy) ethoxy] ethyl group, 2- [2 '-(3 "-chlorophenoxy) ethoxy] ethyl Group, 2- [2 '-(4 "-methoxyphenoxy) ethoxy] ethyl group, 3- (3'-phenoxypropoxy) propyl group and the like.

As specific examples of the benzoic acid derivative represented by the general formula (1) according to the present invention, the following compounds can be exemplified, but of course, the present invention is not limited to these. . Exemplified Compound No. 1. 1. 2- (2'-methoxyethyl) oxycarbonylbenzoic acid 2. 2- (2'-isobutoxyethyl) oxycarbonylbenzoic acid 3. 2- (2'-n-octyloxyethyl) oxycarbonylbenzoic acid 4. 2- (2'-cyclohexyloxyethyl) oxycarbonylbenzoic acid 5. 2- (3'-methoxypropyl) oxycarbonylbenzoic acid 6. 2- (3'-n-butoxypropyl) oxycarbonylbenzoic acid 7. 2- (3'-n-decyloxypropyl) oxycarbonylbenzoic acid 8. 2- (3'-cyclopentyloxypropyl) oxycarbonylbenzoic acid 9. 2- (4'-methoxybutyl) oxycarbonylbenzoic acid 10. 2- (5'-methoxypentyl) oxycarbonylbenzoic acid 12. 2- (6'-methoxyhexyl) oxycarbonylbenzoic acid 12. 2- [2 '-(2 "-methoxyethoxy) ethyl] oxycarbonylbenzoic acid 13.2- [2'-(2" -ethoxyethoxy) ethyl] oxycarbonylbenzoic acid 14. 15. 2- [2 '-(2 "-n-octyloxyethoxy) ethyl] oxycarbonylbenzoic acid 15. 15. 2- [2'-(2" -cyclohexyloxyethoxy) ethyl] oxycarbonylbenzoic acid 16. 17. 2- [3 '-(3 "-methoxypropoxy) propyl] oxycarbonylbenzoic acid 17. 18. 2- [3'-(3" -cyclohexyloxypropoxy) propyl] oxycarbonylbenzoic acid 18. 18. 2- (2'-benzyloxyethyl) oxycarbonylbenzoic acid 2- [2 '-(4 "-methylbenzyloxy)
Ethyl] oxycarbonylbenzoic acid20. 2- [2 '-(4 "-chlorobenzyloxy)
Ethyl] oxycarbonylbenzoic acid 21. 2- [2 '-(4 "-methoxybenzyloxy) ethyl] oxycarbonylbenzoic acid 22. 2- (3'-benzyloxypropyl) oxycarbonylbenzoic acid 23. 2- [2'-(2" -benzyloxy) 20. ethoxy) ethyl] oxycarbonylbenzoic acid 2- [3 ′-(3 ″ -benzyloxypropoxy) propyl] oxycarbonylbenzoic acid 25. 2-phenoxymethyloxycarbonylbenzoic acid 26. 2- (2′-phenoxyethyl) oxycarbonylbenzoic acid 27. 2- [ 2 '-(4 "-methylphenoxy) ethyl] oxycarbonylbenzoic acid 2- [2 '-(3 "-methylphenoxy) ethyl] oxycarbonylbenzoic acid 29. 2- [2'-(2" -methylphenoxy) ethyl] oxycarbonylbenzoic acid 30. 2- [2 '-(4 "-tert-butylphenoxy) ethyl] oxycarbonylbenzoic acid 31. 2- [2'-(4" -chlorophenoxy) ethyl] oxycarbonylbenzoic acid 32. 2- [2 '-(3 "-chlorophenoxy) ethyl] oxycarbonylbenzoic acid 33. 2- [2'-(2" -chlorophenoxy) ethyl] oxycarbonylbenzoic acid 34. 2- [2 '-(4 "-methoxyphenoxy) ethyl] oxycarbonylbenzoic acid 35. 2- [2'-(3" -methoxyphenoxy) ethyl] oxycarbonylbenzoic acid 36. 2- [2 '-(2 "-methoxyphenoxy) ethyl] oxycarbonylbenzoic acid 37. 2- [2'-(4" -nitrophenoxy) ethyl] oxycarbonylbenzoic acid 38. 2- [2 '-(3 "-formylphenoxy) ethyl] oxycarbonylbenzoic acid 39. 2- [2'-(2" -cyanophenoxy) ethyl] oxycarbonylbenzoic acid 40. 2- [2 '-(2 ", 4" -dimethylphenoxy) ethyl] oxycarbonylbenzoic acid41. 42. 2- [2 '-(2 ", 5" -dichlorophenoxy) ethyl] oxycarbonylbenzoic acid 43. 2- [2 '-(2 "-methyl-4" -chlorophenoxy) ethyl] oxycarbonylbenzoic acid 2- [2 '-(2 "-naphthyloxy) ethyl] oxycarbonylbenzoic acid 44. 2- (3'-phenoxypropyl) oxycarbonylbenzoic acid 45. 2- (4'-phenoxybutyl) oxycarbonylbenzoic acid 46 47. 2- [2 '-(2 "-phenoxyethoxy) ethyl] oxycarbonylbenzoic acid 48. 2- {2 '-[2 "-(3'"-methylphenoxy) ethoxy] ethyl} oxycarbonylbenzoic acid 49. 2- {2 '-[2 "-(2'"-chlorophenoxy) ethoxy] ethyl} oxycarbonylbenzoic acid 50. 2- {2 '-[2 "-(4'"-nitrophenoxy) ethoxy] ethyl} oxycarbonylbenzoic acid 2- [3 '-(3 "-phenoxypropoxy)
[Propyl] oxycarbonylbenzoic acid The compound represented by the general formula (1) according to the present invention can be prepared by a known method, for example, Journal of Organic.
Chemistry, Vol. 46 , p1991
(1981) or "New Experimental Chemistry Course", 1st edition,
Vol. 14, page 1014, published by Maruzen Co., Ltd. and the like.

That is, it can be produced by reacting phthalic anhydride with an alcohol represented by the general formula (2).

R—OH (2) (wherein, R has the same meaning as in the above formula (1).) In the heat-sensitive recording material of the present invention, the polyvalent benzoic acid derivative represented by the general formula (1) is used. Metal salts are used. The polyvalent metal salt is preferably a water-insoluble or water-insoluble 2
It is a valent, trivalent or tetravalent metal salt, more preferably a divalent or trivalent metal salt.

Specific examples of the polyvalent metal salt include zinc, cadmium, mercury, magnesium, calcium, barium,
Nickel, tin, lead, gallium, chromium, copper, molybdenum, tungsten, zirconium, strontium, manganese, cobalt, titanium, aluminum and iron salts can be mentioned, preferably zinc, magnesium, calcium, barium, nickel and manganese. , Cobalt, aluminum salts, more preferably zinc, magnesium, nickel, manganese salts, especially zinc salts,
Calcium salts are the preferred metal salts.

In the polyvalent metal salt of the benzoic acid derivative represented by the general formula (1) according to the present invention, the divalent, trivalent and tetravalent metal salts are usually represented by the general formula (1). Alkali metal salts of benzoic acid derivatives (eg, sodium,
A multivalent metal salt of a water-insoluble or water-insoluble benzoic acid derivative from an aqueous solution of a metal salt such as potassium or lithium) and an aqueous solution of the corresponding water-soluble divalent, trivalent or tetravalent metal salt compound by a metathesis method. Manufactured as At this time, if necessary, heating may be performed, or an organic solvent may coexist.

The above water-soluble metal salt compounds include, for example, sulfates such as zinc sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate, zinc chloride, magnesium chloride, calcium chloride, barium chloride, nickel chloride, cobalt chloride, chloride, and the like. Chlorides such as aluminum, zinc acetate,
Acetates such as manganese acetate;

The polyvalent metal salt of the benzoic acid derivative represented by the general formula (1) produced as described above sometimes forms a solvate such as a hydrate depending on the production conditions.
The solvate can also be suitably used for the heat-sensitive recording material of the present invention. Of course, a polyvalent metal salt of a benzoic acid derivative obtained by removing a solvent such as water from the solvate can be produced by a known method (for example, drying). Of course, a non-solvate of the polyvalent metal salt of the benzoic acid derivative can also be suitably used for the heat-sensitive recording material of the present invention.

The heat-sensitive recording material of the present invention comprises a heat-sensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, wherein at least one polyvalent metal salt of a benzoic acid derivative represented by the general formula (1) is used. More specifically, the constitution of the heat-sensitive recording material of the present invention is described. The present invention contains an electron-donating chromogenic compound and an electron-accepting compound, and further comprises a compound represented by the general formula (1). A heat-sensitive recording material containing at least one polyvalent metal salt of a benzoic acid derivative.

In these heat-sensitive recording materials of the present invention,
As will be described later, various known formulations (such as addition of a heat-fusible compound) for producing a known thermosensitive recording material are further provided.

In the heat-sensitive recording material of the present invention, usually,
The electron accepting compound is preferably 50 to 700 parts by weight, and more preferably 100 to 50 parts by weight, based on 100 parts by weight of the electron donating color forming compound.
0 parts by weight, and 10 to 700 parts by weight, preferably 2 parts by weight of the polyvalent metal salt of the benzoic acid derivative represented by the general formula (1).
It is desirable to use 0 to 500 parts by weight.

The colorless or pale-color electron-donating color-forming compound used in the present invention includes a triarylmethane compound, a diarylmethane compound, a rhodamine-lactam compound, a fluoran compound, an indolylphthalide compound, and pyridine. Compounds, spiro compounds, fluorene compounds and the like.

Some specific examples of these compounds include, as triarylmethane compounds, 3,3-
Bis (4'-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (4'-dimethylaminophenyl)
Phthalide, 3- (4'-dimethylaminophenyl) -3
-(1 ", 3" -dimethylindol-3 "-yl) phthalide, 3- (4'-dimethylaminophenyl) -3-
(2 "-methylindole-3" -yl) phthalide,
3,3-bis (9'-ethylcarbazol-3'-yl) -6-dimethylaminophthalide, 3- (4'-dimethylaminophenyl) -3- (1 "-methylpyrrol-
3 "-yl) -6-dimethylaminophthalide, 3,3-
Bis [2 ′, 2′-bis (p-dimethylaminophenyl) ethenyl] -4,5,6,7-tetrachlorophthalide;

As the diarylmethane compound, 4,
4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine, N-2,
4,5-trichlorophenyl-leuco auramine and the like.

The rhodamine-lactam compounds include:
Rhodamine-B-anilinolactam, rhodamine- (4
-Nitroanilino) lactam, rhodamine-B- (4-
(Chloroanilino) lactam and the like.

Examples of the fluoran compounds include 3,6-dimethoxyfluoran, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran, Diethylamino-7-chlorofluoran, 3-
Diethylamino-6-methyl-7-chlorofluoran,
3-diethylamino-6,7-dimethylfluoran, 3
-N-cyclohexyl-NN-butylamino-7-methylfluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-di-n −
Hexylaminofluoran, 3-diethylamino-7-
Anilinofluoran, 3-diethylamino-7- (2 ′
-Chloroanilino) fluoran, 3-diethylamino-
7- (3′-chloroanilino) fluoran, 3-diethylamino-7- (2 ′, 3′-dichloroanilino) fluoran, 3-diethylamino-7- (3′-trifluoromethylanilino) fluoran, 3-di -N-butylamino-7- (2'-chloroanilino) fluoran, 3-
Diethylamino-6-chloro-7-anilinofluoran, 3-di-n-butylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-methoxy-
7-anilinofluoran, 3-di-n-butylamino-
6-ethoxy-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-morpholino-6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl- 7-anilinofluoran, 3
-Diethylamino-6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-di-n-pentylamino-6-methyl-7-ani Rinofluoran, 3-di-n-octylamino-6-methyl-7-anilinofluoran, 3-N
-Ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-n-propyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-n
-Propyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopropyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-
n-butyl-N-methylamino-6-methyl-7-anilinofluoran, 3-Nn-butyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-Nn
-Butyl-N-n-propylamino-6-methyl-7-
Anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N
-Isobutyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N
-N-hexyl-N-ethylamino-6-methyl-7-
Anilinofluoran, 3-NN-octyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-
N-cyclohexyl-N-methylamino-6-methyl-
7-anilinofluoran, 3-N-cyclohexyl-N
-N-propylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-NN-butylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-NN -Pentylamino-6-methyl-
7-anilinofluoran, 3-N-cyclohexyl-N
-N-hexylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-Nn-heptylamino-6-methyl-7-anilinofluoran, 3-N-
Cyclohexyl-Nn-octylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-
Nn-decylamino-6-methyl-7-anilinofluoran, 3-N- (2'-methoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-
N- (2'-methoxyethyl) -N-ethylamino-6
-Methyl-7-anilinofluoran, 3-N- (2'-
Methoxyethyl) -N-isobutylamino-6-methyl-7-anilinofluoran, 3-N- (2′-ethoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3- N- (2'-ethoxyethyl) -N
-Ethylamino-6-methyl-7-anilinofluoran, 3-N- (3'-methoxypropyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N
-(3'-methoxypropyl) -N-ethylamino-6
-Methyl-7-anilinofluoran, 3-N- (3'-
Ethoxypropyl) -N-methylamino-6-methyl-
7-anilinofluoran, 3-N- (3'-ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2'-tetrahydrofurfuryl) -N- Ethylamino-6-methyl-7-anilinofluoran, 3-N- (4'-methylphenyl) -N-ethyl-6-methyl-7-anilinofluoran, 3-diethylamino-6-ethyl-7 -Anilinofluoran, 3
-Diethylamino-6-ethyl-7- (3′-methylanilino) fluoran, 3-diethylamino-6-methyl-7- (2 ′, 6′-dimethylanilino) fluoran,
3-di-n-butylamino-6-methyl-7- (2 ′,
6'-dimethylanilino) fluoran, 3-di-n-butylamino-7- (2 ', 6'-dimethylanilino) fluoran, 2,2-bis [4'-(3 "-N-cyclohexyl-) N-methylamino-6 "-methylfluoran-
7 "-yl) aminophenyl] propane, 3- [4'-
(4 "-anilinophenyl) aminophenyl] amino-
6-methyl-7-chlorofluoran and the like.

As the indolylphthalide compound,
3,3-bis (1′-ethyl-2′-methylindol-3′-yl) phthalide, 3,3-bis (1′-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 and the like.

As the pyridine compound, 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" -methylindol-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, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran,
Benzyl-spiro-dinaphthopyran, 3-methylnaphtho- (3'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran and the like.

As the fluorene compound, 3 ', 6'
-Bisdiethylamino-5-diethylaminospiro (isobenzofuran-1,9'-fluoren) -3-one,
3 ′, 6′-bisdiethylamino-7-diethylamino-2-methylspiro (1,3-benzoxazine-4,
9'-fluorene).

These electron-donating color-forming compounds may be used alone,
Alternatively, two or more kinds may be used in combination for the purpose of adjusting the color tone of a color-formed image or obtaining a multicolor heat-sensitive recording material.

As the electron-donating color-forming compound, a fluoran-based compound which develops black color is particularly preferable.
-Di-n-butylamino-7- (2'-chloroanilino) fluoran, 3-dimethylamino-6-methyl-7
-Anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-di-n
-Pentylamino-6-methyl-7-anilinofluoran, 3-NN-propyl-N-methylamino-6-methyl-7-anilinofluoran, 3-NN-butyl-
N-methylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-
N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2'-methoxyethyl) -N-isobutylamino-6-methyl-7-anilinofluoran, 3-
N- (3'-ethoxypropyl) -N-ethylamino-
6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7- (3′-methylanilino) fluoran are excellent in photostability when color is not developed, and are particularly preferable electron-donating color-forming compounds. It is.

The electron-accepting compound used in the present invention includes organic electron-accepting compounds such as phenol derivatives, organic acids or metal salts and complexes thereof, urea derivatives, and inorganic electron-accepting compounds such as acid clay. .

Some specific examples of these compounds include 4-tert-butylphenol and 4-tert-butylphenol.
-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 [also known as bisphenol A],
1,1-bis (4′-hydroxyphenyl) cyclohexane, 2,2-bis (4′-hydroxy-3′-methylphenyl) propane, 1,4-bis (4′-hydroxycumyl) benzene, 3,5-tris (4′-hydroxycumyl) benzene, 4,4- (m-phenylenediisopropylidene) bisphenol, 4,4- (p-phenylenediisopropylidene) bisphenol, 2,2-
Ethyl bis (4′-hydroxyphenyl) acetate, n-butyl 4,4-bis (4′-hydroxyphenyl) pentanoate, benzyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, 2, 4-dihydroxybenzoic acid 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, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4'-bishydroxydiphenylsulfone, 4-hydroxy-
4'-methyldiphenylsulfone, 4-hydroxy-
4'-chlorodiphenylsulfone, 4-hydroxy-
4'-n-propoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone,
4-hydroxy-4'-n-butoxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, 2,4-dihydroxydiphenylsulfone, 2-methoxy-4'-hydroxydiphenylsulfone, 2-ethoxy-4 '-Hydroxydiphenylsulfone, bis (2-hydroxy-5-tert-butylphenyl) sulfone, bis (2-hydroxy-5-chlorophenyl) sulfone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 1,7-
Phenol derivatives such as bis (4-hydroxyphenylthio) -3,5-dioxaheptane and 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, salicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid 3,5-di-tert-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid,
3-methyl-5-α-methylbenzylsalicylic acid, 4-
[2 ′-(4-methoxyphenyloxy) ethyloxy] 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,
Organic acids such as 4-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, phenylthiourea, bis ( 3-trifluoromethylphenyl) thiourea, 1,4-bis (3'-chlorophenyl)
Organic electron-accepting compounds such as urea derivatives such as -3-thiosemicarbazide, and inorganic electron-accepting compounds such as acid clay, attapulgite, activated clay, aluminum chloride, zinc chloride and zinc bromide can be mentioned as preferred compounds. These electron accepting compounds may be used alone or
You may mix and use more than one kind.

Further, in order to improve the color sensitivity, a heat-fusible compound (compound having a melting point of about 70 to 150 ° C., more preferably a melting point of about 80 to 130 ° C.) is used as a sensitizer in the heat-sensitive recording material of the present invention. The addition is preferable for obtaining a heat-sensitive recording material compatible with high-speed recording.

In this case, it is usually desirable to use 10 to 700 parts by weight, preferably 20 to 500 parts by weight of the heat-fusible compound with respect to 100 parts by weight of the electron-donating color-forming compound.

Specific examples of such a heat-fusible compound include:
For example, nitrogen-containing compounds such as caproic amide, capric amide, stearic amide, palmitic amide, oleic amide, stearyl urea, stearic anilide, N-ethylcarbazole, 4-methoxydiphenylamine, 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,
Ester compounds such as glutaric acid diphenacyl ester, di (4-methylphenyl) carbonate and terephthalic acid dibenzyl ester, 4-benzylbiphenyl, m-
Terphenyl, fluorene, fluoranthene, 2,6-
Hydrocarbon compounds such as diisopropylnaphthalene and 3-benzylacenaphthene, 2-benzyloxynaphthalene, 2- (4′-methylbenzyloxy) naphthalene,
1,4-diethoxynaphthalene, 1,2-diphenoxyethane, 1,2-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′-methylphenyloxymethyl) benzene, 1,4-bis (3′-methylphenyloxymethyl) benzene,
-Chlorobenzyloxy-4'-ethoxybenzene,
4,4′-bisphenoxydiphenyl ether, 4,
4'-bisphenoxydiphenylthioether, 1,4
-Bis (4'-benzylphenoxy) benzene, 1,4
And ether compounds such as -bis [(4'-methylphenyloxy) methoxymethyl] benzene. These heat-fusible compounds may be used alone or in combination of two or more.

The heat-sensitive recording material of the present invention can be manufactured by a known method without using a special method.

In general, an electron-donating color-forming compound, an electron-accepting compound, and a polyvalent metal salt of a benzoic acid derivative represented by the general formula (1) are each dissolved in a water-soluble binder in a ball mill, a sand mill, or the like. In general, a coating liquid for a recording layer can be prepared by pulverizing and dispersing the particles to a particle size of 3 μm or less, preferably 1.5 μm or less by means of a horizontal sand mill, an attritor, a colloidal mill or the like.

Specific examples of such a water-soluble binder include polyvinyl alcohol, sulfonated polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin modified polyamide, ethylene-maleic anhydride copolymer, styrene-anhydride. Maleic acid copolymer, isobutylene-maleic anhydride copolymer, polyacrylic acid, polyacrylamide, methylol-modified polyacrylamide, starch derivative casein, gelatin, methylcellulose, carboxymethylcellulose, gum arabic, carboxyl-modified polyvinyl alcohol, and the like. be able to.

If necessary, the recording layer of the heat-sensitive recording material of the present invention may contain a pigment, a water-insoluble binder, a metal soap, a wax, a surfactant, an ultraviolet absorber, a hindered phenol, an antifoaming agent and the like. Added.

Examples of pigments include zinc oxide, zinc carbonate, calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, titanium oxide, talc, fluorite, kaolin, diatomaceous earth, aluminum hydroxide, magnesium hydroxide, alumina, silica, Amorphous silica, urea-formalin filler, polyethylene particles, cellulose filler and the like are used.

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, and styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion and the like are known. Used as needed.

As the metal soap, higher fatty acid metal salts are used, and zinc stearate, calcium stearate,
Aluminum stearate, zinc oleate and the like are used.

As the wax, paraffin wax,
Microcrystalline wax, carboxy-modified paraffin wax, carnauba wax, polyethylene wax, polystyrene wax, canderia wax,
Montan wax, higher fatty acid esters and the like.

Examples of the surfactant include sulfosuccinic acid-based alkali metal salts [eg, sodium salts such as di (n-hexyl) sulfosuccinic acid and di (2-ethylhexyl) sulfosuccinic acid], and fluorine-containing surfactants. No.

Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazolyl phenol derivatives and the like.

The hindered phenol is preferably a phenol derivative in which at least one ortho position of the phenolic hydroxyl group has been substituted with a branched alkyl group.
3-tris (2-methyl-4-hydroxy-5-ter
t-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, 2,2′-methylenebis (6-t
tert-butyl-4-methylphenol), 2,2'-
Methylenebis (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-ter
t-butyl-3-hydroxy-2-methyl-6-ethylbenzyl) isocyanuric acid, bis (2-methyl-4-hydroxy-5-tert-butylphenyl) sulfide and the like.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and it can be formed according to a conventionally known technique.

For example, a coating solution for thermal recording is coated on a support by a suitable coating device such as an air knife coater, a blade coater, a bar coater, a gravure coater, a curtain coater, a wire bar and the like, and dried to form a recording layer. Can be formed.

The coating amount of the coating liquid is not particularly limited, and is generally 1.5 to 12 g / m2 in dry weight.
² , preferably in the range of 2.5 to 10 g / m ² .

As the support, paper, plastic sheet,
Synthetic paper is used.

If necessary, a protective layer may be provided on the front and / or back surface of the heat-sensitive recording layer, or an undercoat layer may be provided between the support and the heat-sensitive recording layer. Various known techniques in a method for producing a heat-sensitive recording material, such as application of the recording medium, may be applied.

[0057]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Production Examples and Examples, but the present invention is not limited to these Production Examples and Examples. Note that, in Production Examples and Examples,% represents% by weight.

[Production Example of Polyvalent Metal Salt of Benzoic Acid Derivative Represented by General Formula (1)] Production Example 1 (Production of zinc salt of compound of Exemplified Compound No. 26) 107 g of phthalic anhydride and 2-phenoxyethanol 10
3.0 g of pyridine was added to a suspension obtained by adding 400 ml of toluene to 0 g. After stirring at 80 ° C for 12 hours, 500 ml of 3% hydrochloric acid was added to the reaction solution, and the mixture was stirred at room temperature for 30 minutes to remove pyridine. Then, the organic layer was separated and taken out.
Further, it was washed three times with 500 ml of warm water. After concentrating the organic layer taken out and separating and filtering the precipitated crystals, the obtained crystals were recrystallized from 300 ml of toluene to give 2-
197 g of (2′-phenoxyethyl) oxycarbonylbenzoic acid were obtained as colorless crystals.

Yield 95% Melting point 108-110 ° C. 43.0 g of 2- (2′-phenoxyethyl) oxycarbonylbenzoic acid was added to 300 ml of methanol and 100 ml of water.
and 12.6 g of sodium hydrogen carbonate
Was slowly added at room temperature, followed by stirring at room temperature for 1 hour. To the obtained solution, 200 ml of an aqueous solution containing 21.6 g of zinc sulfate heptahydrate was added dropwise at room temperature over 1 hour. After the dropwise addition, the mixture was further stirred at room temperature for 3 hours, and the precipitated crystals were filtered, washed with water and dried to obtain 42.3 g of zinc salt of 2- (2′-phenoxyethyl) oxycarbonylbenzoic acid as colorless crystals. Was.

Yield: 89% Melting point: 100 to 105 ° C. [Evaluation method of thermosensitive recording paper] The whiteness of undeveloped portions (background) immediately after application of each thermosensitive recording paper produced in the following Examples and Comparative Examples was measured by a color difference meter. (Σ-80, manufactured by Nippon Denshoku).

Further, each thermosensitive recording paper was subjected to a Macbeth densitometer (TR) using a thermosensitive coloring device (TH-PMD, manufactured by Okura Electric Co., Ltd.).
After forming a color image having a color density of 0.9 as measured using (-524 type), a storage stability test of the color image shown below was performed.

1. Moisture / Heat Resistance Test The density of a color image after the heat-sensitive recording paper was stored at 60 ° C. and 90% relative humidity for 24 hours was measured using a Macbeth densitometer to determine the residual ratio of the color image.

2. Oil resistance test Capsule coated paper containing dioctyl phthalate is superimposed on thermosensitive recording paper, passed through a pressure roll, and stored at 25 ° C for one week, and the color image density measured using a Macbeth densitometer Then, the residual ratio of the color image was determined.

The residual ratio of the color image in each test was determined by the following equation. Residual rate (%) = (color image density after each test / color image density before test (0.9)) × 100 The larger the numerical value, the better the storage stability of the color image.

Examples 1 to 13 [Preparation of thermosensitive recording paper] (Composition A) 10 g of electron-donating color-forming compound, 10 g of 10% aqueous solution of polyvinyl alcohol (Kuraray-117),
80 g of water (100 g in total).

(Solution B) 20 g of electron-accepting compound (bisphenol A), light calcium carbonate (Okutama Kogyo,
TP-123) 40 g, 10% polyvinyl alcohol (Kuraray-117) aqueous solution 10 g, water 130 g (25 in total)
0 g).

(Composition C) 20 g of a polyvalent metal salt of a benzoic acid derivative represented by the general formula (1), 10 g of a 10% aqueous solution of polyvinyl alcohol (Kuraray-117), and 220 g of water
(Total 250 g).

(D composition) 20 g of a heat-fusible compound (2-benzyloxynaphthalene), 10 g of a 10% aqueous solution of polyvinyl alcohol (Kuraray-117), and 220 g of water (250 g in total).

The above solutions A, B, C, and D were each dispersed by a sand grinding mill so that the average particle diameter was 1.5 μm or less to prepare dispersions.

A solution 100 g, B solution 250 g, C solution 250
g, a dispersion of 250 g of solution D and 23 g of 30% paraffin wax, and this was applied to a high-quality paper with a dry coating amount of 5.0 g.
The coating was performed so as to be ± 0.5 g / m ² and dried to prepare a thermosensitive recording paper.

Table 1 shows the electron-donating color-forming compound in Solution A and the polyvalent metal salt of the benzoic acid derivative represented by the general formula (1) in Solution C used in each Example.

[0072]

[Table 1] Comparative Examples 1 and 2 A thermosensitive recording paper was prepared by the above-mentioned method using the solution A, the solution B and the solution D, without using the solution C, using the electron-donating color-forming compounds shown in Table 2.

[0073]

[Table 2] Comparative Examples 3 and 4 3-di-n-butylamino-6-methyl-7-anilinofluoran was used as an electron-accepting compound in solution A, and was represented by general formula (1) in solution C. Thermal recording paper was prepared in the same manner as described above, except that the compounds shown in Table 3 were used instead of the polyvalent metal salt of the benzoic acid derivative.

[0074]

[Table 3] Table 4 shows the results of the wet heat resistance test and the oil resistance test of the whiteness and the color image immediately after the application of each of the heat-sensitive recording papers obtained in Examples 1 to 13 and Comparative Examples 1 to 4.

[0075]

[Table 4] As is clear from Table 4, the heat-sensitive recording material of the present invention
Compared with the conventional heat-sensitive recording material, the storage stability (moisture heat resistance and oil resistance) of the color image is very excellent, and the whiteness of the background immediately after coating is practically no problem.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoharu Hasegawa 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside of Mitsui Toatsu Chemical Co., Ltd. Inside (72) Inventor Masakatsu Nakatsuka 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemicals Co., Ltd. (56) References JP-A-63-205279 (JP, A) JP-A-63-257680 (JP) JP-A-62-80089 (JP, A) JP-A-2-238991 (JP, A) JP-A-62-148288 (JP, A) JP-A-50-7440 (JP, A) 60-46293 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (2)

(57) [Claims] 1. A thermosensitive recording material containing an electron-donating color-forming compound and an electron-accepting compound, comprising a zinc salt or a calcium salt of a benzoic acid derivative represented by the general formula (1).
A heat-sensitive recording material containing at least one selected polyvalent metal salt. Embedded image (Wherein, R is an alkyl group having 1 to 20 carbon atoms, 6 to
20 aryl groups, aryloxy having 6 to 20 carbon atoms
Group, aralkyloxy group having 7 to 20 carbon atoms, halogen atom
The alkoxy component is monosubstituted or polysubstituted
A good alkoxyalkyl group having 2 to 24 carbon atoms , or
Total aryloxyalkyl group having 7 to 24 carbon atoms and table,
The aryl group contained in R is an alkyl group having 1 to 6 carbon atoms.
Group, an alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 7 to 10 carbon atoms
An aralkyl group, an aralkyloxy group having 7 to 10 carbon atoms,
Mono-substituted with toro, formyl, halogen and cyano groups
Alternatively, it may be polysubstituted. ) 2. The method according to claim 1, wherein the electron-donating color-forming compound is 3-di-n.
-Butylamino-7- (2'-chloroanilino) fluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-n -Butylamino-6-methyl-7-anilinofluoran, 3-di-n-pentylamino-6-methyl-7-anilinofluoran, 3-N
-N-propyl-N-methylamino-6-methyl-7-
Anilinofluoran, 3-Nn-butyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N
-Isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N
-(2'-methoxyethyl) -N-isobutylamino-
6-methyl-7-anilinofluoran, 3-N- (3 ′
-Ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran and 3-diethylamino-
The heat-sensitive recording material according to claim 1, wherein the material is selected from the group consisting of 6-methyl-7- (3'-methylanilino) fluoran.