JP2002205462A - Heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium having excellent color developing sensitivity, whiteness, good ground color preservability, and a small decrease in printability (good reprintability) even when the medium is left to stand under high temperature and high humidity. SOLUTION: The heat-sensitive recording medium comprises a heat-sensitive color developing layer containing at least one type of a sulfonamidephenol derivative represented by formula (1) as an organic developer. X is a hydrogen atom, halogen atom, alkyl group, hydroxyl group, alkoxy group or nitro group. R1 to R5 are each a hydrogen atom, halogen atom, alkyl group, cycloalkyl group, aralkyl group, aryl group, alkenyl group, alkoxyl group, cycloalkoxyl group, alkenyloxy group, nitro group or acyl group. R1 and R2 or R2 and R3 may form an aromatic ring, and further at least one type of a compound represented by formula (2), wherein R6 is H or CH3 and R7 is H or an electron- attracting group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium utilizing a color development reaction between a basic colorless dye and an organic color developer.

[0002]

2. Description of the Related Art A thermosensitive recording medium having a thermosensitive coloring layer mainly composed of a colorless or pale-colored dye precursor and a color developing agent which reacts with the dye precursor by heating to form a color is disclosed in JP-B-45-14.
No. 039, which is widely used. In order to perform recording on this thermal recording medium, a thermal printer or the like having a built-in thermal head is used, but such a thermal recording method is compared with other recording methods that have been practically used in the past.
With features such as no noise at the time of recording, no need for development and fixing, maintenance-free, relatively inexpensive and compact equipment, and very clear color development, with the development of the information industry, Widely used in facsimile and computer fields, various measuring instruments, labels, etc. With the diversification and high performance of these recording apparatuses, the required quality of the thermosensitive recording medium has become higher. As for the color sensitivity, as the size of the apparatus is reduced and the recording speed is increased, it is required that a clear color image with high density can be obtained even with a small amount of thermal energy.

In order to satisfy these requirements, for example, JP-A-56-169087 discloses a method of increasing the color sensitivity by adding a heat-soluble substance to a heat-sensitive layer.
No. 6,144,193 describes a method of increasing the color development sensitivity by using a new color developer having a high color developing ability. However, any of these methods deteriorates the heat-resistant ground color, powders over time, It is difficult to say that the quality is sufficient because it has disadvantages such as a reduction in the color density (reprintability) when printing after storing the color forming portion for a long time. Further, generally, a method of using a further appropriate sensitizer in combination with a dye and a developer is known,
For example, when the developer is a phenolic compound represented by bisphenol A, p-benzylbiphenyl (JP-A-60-82382), benzyl p-benzyloxybenzoate (JP-A-57-201691), benzyl Naphthyl ether (JP-A-58-87094) and the like have been used as suitable sensitizers.

[0004] On the other hand, the thermal recording medium has been developed for use in a natural environment such as heat, water, humidity and light, body fat when handled by hand, or an oil, a plasticizer, a solvent, etc., with the spread of usage. Storage stability and good ground color are also required.
The sulfonamide phenol derivative used as an organic color developer in the present invention has a color developing ability that does not meet recent high sensitivity requirements, and a heat-sensitive recording medium having other quality performance while realizing high sensitivity is required. Not yet obtained.

[0005]

DISCLOSURE OF THE INVENTION The present invention is excellent in color sensitivity, good in whiteness and preservability of ground color, and has little decrease in printing ability even when left under high temperature and high humidity. (Good).

[0006]

SUMMARY OF THE INVENTION As a result of the present inventors' earnest studies, the present inventors have found that a thermosensitive recording layer provided with a thermosensitive coloring layer containing a colorless or pale-colored basic colorless dye and a developer as main components. In the body, the thermosensitive coloring layer contains at least one sulfonamide phenol derivative represented by the following general formula (1) as an organic developer, and further contains a compound represented by the following general formula (2). Achieved.

[0007]

Embedded image (X is a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, an alkoxyl group, or a nitro group, and R _{1 to} R ₅ are a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, an alkenyl group. , An alkoxyl group, a cycloalkoxyl group, an alkenyloxy group, a nitro group, or an acyl group, wherein R ₁ and R ₂ or R ₂
And R ₃ may form an aromatic ring. )

[0008]

Embedded image (In the formula, R ₆ represents H or CH ₃ , and R ₇ represents H or an electron withdrawing group.)

In general, it is assumed that the color development sensitivity of a thermosensitive recording medium is affected by the melt-dissolution rate of a dye and a developer and the saturation solubility. In order to improve these, it is known to add various materials as sensitizers, and the addition of the sensitizer lowers the melting point, changes the polarity, lowers the activation energy, and improves the compatibility between the materials. It is thought that many factors work in a complicated manner, and the melt-dissolution diffusion rate and the saturation solubility increase, thereby promoting the improvement of the color sensitivity.

The compound represented by the general formula (2) used in the present invention is a compound having a sensitizing effect, and the present invention provides a compound having an extremely high sensitivity when combined with an organic developer represented by the general formula (1). It has been found that a thermosensitive recording medium can be obtained which has high color development sensitivity, good whiteness, and preservability of ground color, and has a small decrease in printing ability even when left under high temperature and high humidity. Although the reason for this has not been clearly elucidated, the compound represented by the general formula (2) has an amide group (—CONH—), and has an aminosulfonyl group (—SO ₂ NH) of a sulfonamide phenol derivative.
It is considered that the structure is similar to that of-), so that the compatibility is excellent and, as a result, the sensitivity is increased. In addition, it is considered that a good ground color is maintained due to the relatively low solubility of the sulfonamide phenol derivative in water.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a thermosensitive recording medium of the present invention,
For example, a dispersion in which a dye, a compound represented by the general formula (1) or a compound represented by the general formula (2) is dispersed together with a binder is mixed, and a filler or other necessary additives are added to prepare a thermosensitive coloring layer coating solution. The thermosensitive recording medium of the present invention can be manufactured by forming a thermosensitive coloring layer by coating and drying on a material.

In the present invention, an organic developer represented by the general formula (1)
A sulfonamide phenol derivative represented by the formula: Specific examples of the compound represented by the general formula (1) include: N-benzenesulfonyl-m-aminophenol (1
-1) N-benzenesulfonyl-p-aminophenol (1
-2) N- (p-toluenesulfonyl) -m-aminophenol (1-3) N- (p-toluenesulfonyl) -p-aminophenol (1-4) N- (2,4-dimethylbenzenesulfonyl) -M-aminophenol (1-5) N- (2,4-dimethylbenzenesulfonyl) -p-aminophenol (1-6) N- (p-chlorobenzenesulfonyl) -m-aminophenol (1-7) N- (p-chlorobenzenesulfonyl) -p-aminophenol (1-8) N- (α-naphthalenesulfonyl) -m-aminophenol (1-9) N- (α-naphthalenesulfonyl) -p-aminophenol (1-10) N- (β-naphthalenesulfonyl) -m-aminophenol (1-11) N- (β-naphthalenesulfonyl) -p-aminophenol Nord (1-12) and the like although not limited thereto.
Among them, the compound (1-
2) is most preferably used. These developers may be used alone or in combination of two or more.

The present invention contains at least one compound represented by the general formula (2). In the general formula (2), R
₆ may be a hydrogen atom or a substituent that does not inhibit the sensitizing effect, and examples of such a substituent include an alkyl group such as a methyl group. On the other hand, R ₇ may be a hydrogen atom or a substituent which does not inhibit the sensitizing effect. Examples of such a substituent include a halogen atom such as a chlorine atom and a bromine atom and an alkoxy group such as a methoxy group and an ethoxy group. Electron-withdrawing groups; Specific examples of the compound represented by the general formula (2) are shown below (2-1)
To (2-19), but are not limited thereto. In the present invention, (2-1) or (2-
8) is preferably used.

[0014]

Embedded image

[0015]

Embedded image

As the leuco-developing basic leuco dye used in the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and there is no particular limitation. Compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical colorless or pale color dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [ Malachite green lactone] <Fluoran leuco dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethyl Anilino) fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o- Chloroanilino) fluoran 3-diethylamino-6-meth Le-7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7- (m-methylanilino) fluoran 3-diethylamino-6 Methyl-7-n-octylanilinofluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl- 7-dibenzylanilinofluoran 3-diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilino Fluoran 3-diethylamino-6-ethoxyethyl-7-anilinov Oran 3-diethylamino-7-methylfluoran 3-diethylamino-7-chlorofluoran 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran 3-diethylamino -7- (p-chloroanilino) fluoran 3-diethylamino-7- (o-fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-dibutylamino-6-methyl- Fluoran 3-dibutylamino-6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutylamino-6-methyl-7- (o -Chloroanilino) fluoran 3-djibuti Amino-6-methyl-7- (p-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethyl Anilino) fluoran 3-dibutylamino-6-methyl-chlorofluorane 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutyl Amino-6-methyl-7-p-methylanilinofluoran 3-dibutylamino-7- (o-chloroanilino) fluoran 3-dibutylamino-7- (o-fluoroanilino) fluoran

3-Di-n-pentylamino-6-methyl-7-anilinofluoran 3-di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-anilinofluoran 3-di-n-pentyl Amino-7- (p-chloroanilino) fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran 3- (N-methyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran 3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluorane 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran 2,4-dimethyl- 6-[(4-dimethylamino) anilino] -fluoran

<Fluorene Leuco Dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-Tris (diethylamino) spiro [fluorene-9,3 '-Phthalide] <Divinyl leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5,
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5,
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide <Others> 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above objects are not impaired. Examples of such a sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, and β-benzylamide. Benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, 4,4'-
Ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, 1,2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl ]
Ether, methyl p-nitrobenzoate, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, dibenzyl terephthalate, p
Benzyl benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate,
1,4-diethoxynaphthalene, 1-hydroxy-2-
Naphthoic acid phenyl ester, o-xylene-bis-
Examples thereof include (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl, orthotoluenesulfonamide, and paratoluenesulfonamide.
It is not particularly limited to these. These sensitizers may be used alone or in combination of two or more.

The binder used in the present invention is a completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, a partially saponified polyvinyl alcohol, a carboxy-modified polyvinyl alcohol, an amide-modified polyvinyl alcohol, a sulfonic acid-modified polyvinyl alcohol, a butyral-modified polyvinyl alcohol. Alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethyl cellulose, acetyl cellulose, polyvinyl chloride, polyacetic acid vinyl,
Examples thereof include polyacrylamide, polyacrylate, polyvinylbutylalal, polystyrene and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumaro resin. These high-molecular substances are used by dissolving them in solvents such as water, alcohols, ketones, esters, and hydrocarbons. They can be used together.

In the present invention, 4,4'-butylidene (6-t-butyl-3) is used as an image stabilizer which exhibits an oil resistance effect of a recorded image, as long as the desired effect on the above-mentioned object is not impaired. -Methylphenol) 2,2'-di-t-butyl-5,5'-dimethyl-4,
4'-sulfonyldiphenol 1,1,3-tris (2-methyl-4-hydroxy-5
-Cyclohexylphenyl) butane 1,1,3-tris (2-methyl-4-hydroxy-5
-T-butylphenylbutane 4-benzyloxy-4 '-(2,3-epoxy-2-
Methylpropoxy) diphenylsulfone epoxy resin A diphenylsulfone cross-linkable compound described in JP-A-10-29969 can also be added.

The filler used in the present invention includes silica,
Examples include inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. In addition, lubricants such as waxes, benzophenone-based or triazole-based ultraviolet absorbers, water-proofing agents such as glyoxal, dispersants, defoamers, antioxidants, fluorescent dyes, and the like can be used.

The amounts of the developer and dye used in the heat-sensitive recording medium of the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. , A developer 1 represented by the general formula (1)
Parts to 0.1 to 2 parts of a basic colorless dye and 0.5 parts of a filler
４4 parts are used, and the binder is suitably used in an amount of 5-25% of the total solid content.

The desired heat-sensitive recording sheet can be obtained by applying a coating solution having the above composition to any support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, and nonwoven fabric. Further, a composite sheet obtained by combining these may be used as the support.

Further, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability. In addition, an undercoat layer of a polymer material containing a filler or the like can be provided below the heat-sensitive layer for the purpose of increasing the coloring sensitivity. The aforementioned organic developer, basic colorless dye and optionally added materials are pulverized to a particle size of several microns or less by a pulverizer such as a ball mill, an attritor, a sand glider or an appropriate emulsifier, and a binder. And various additive materials are added according to the purpose to form a coating liquid. Means for applying is not particularly limited,
Coating can be carried out according to well-known conventional techniques. For example, an off-machine coating machine or an on-machine coating machine equipped with various coaters such as an air knife coater, a rod blade coater, a bill blade coater, and a roll coater is appropriately selected and used.

[0027]

The present invention will be described below with reference to examples.
In addition, in description, a part shows a weight part. [Examples 1 to 3] In Examples 1 to 3, compounds (1-2) were used as a developer, ODB-2 was used as a basic colorless dye, and compounds (2-1) and (2-8) were used as sensitizers. , (2-10). Each material of the dye, the developer and the sensitizer was prepared in advance as a dispersion having the following composition, and was wet-milled with a sand grinder until the average particle size became 0.5 μm. <Developer dispersion> Compound (1-2) 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts <Dye dispersion> 3-di-n-butylamino-6-methyl-7 -Anilinofluoran (ODB-2) 3.0 parts 10% aqueous polyvinyl alcohol solution 6.9 parts Water 3.9 parts <Sensitizer dispersion> Sensitizer 4.0 parts 10% aqueous polyvinyl alcohol solution 18.8 Part water 11.2 parts The following compositions were mixed to obtain a coating liquid. The coating liquid application amount after drying fine paper having a basis weight of 50 g / m ² and is applied and dried such that the 6 g / m ^2, Bekk smoothness is treated to be 200-600 seconds supercalendered, A thermosensitive recording medium was obtained. Developer dispersion (Compound (1-2)) 36.0 parts Dye dispersion (ODB-2) 13.8 parts Sensitizer dispersion 34.0 parts Kaolin clay 50% dispersion 26.0 parts Stearic acid 6.7 parts of 30% zinc dispersion

Example 4 In Example 4, compound (1-2) was used as a developer, ODB-2 was used as a basic colorless dye, and compounds (2-1) and (2-10) were used as sensitizers. This is an example used. Compound (1-1) was prepared in the same manner as in Examples 1 to 3.
The developer dispersion of 0), the basic colorless dye dispersion, and the sensitizer dispersions of compounds (2-1) and (2-10) were treated. The following compositions were mixed to obtain a coating solution. The coating amount after drying this coating solution on a high-quality paper having a basis weight of 50 g / m ² is 6 g / m 2.
^Then , the coating was dried so as to be ^2, and treated with a super calender so that the Beck smoothness became 200 to 600 seconds to obtain a thermosensitive recording medium. Developer dispersion (Compound (1-2)) 36.0 parts Dye dispersion (ODB-2) 13.8 parts Sensitizer dispersion (Compound (2-1)) 17.0 parts Sensitizer dispersion Liquid (Compound (2-10)) 17.0 parts Kaolin clay 50% dispersion 26.0 parts Zinc stearate 30% dispersion 6.7 parts

Comparative Example 1 The procedure of Example 1 was repeated, except that the compound (1-2) in the developer dispersion was changed to 4,4'-isopropylidenediphenol (BPA). A thermosensitive recording medium was obtained.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1. However, the sensitizer dispersion used was obtained from the following materials and formulations. <Sensitizer Dispersion> Parabenzylbiphenyl (PBB) 4.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Wet grinding was performed with a sand grinder to an average particle size of 0.5 μm.

Comparative Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the sensitizer dispersion was not used.

[Coloring sensitivity] TH-PMD manufactured by Okura Electric Co., Ltd.
And the applied energy of 0.3
Printing was performed at 4 mJ / dot. The image density after printing and after the quality test was measured with a Macbeth densitometer (using an amber filter). [Background Whiteness] The whiteness of the sample in the uncolored portion was measured with a Macbeth densitometer (using an amber filter). [Heat-Resistant Ground Color] The sample pieces in the uncolored portion were left in an atmosphere at 60 ° C. for 24 hours, and then measured with a Macbeth densitometer (using an amber filter). [Wet heat resistant ground color] 60% 90%
After standing for 24 hours in an atmosphere of, the measurement was performed with a Macbeth densitometer (using an amber filter). [Reprintability] After leaving the sample of the uncolored portion in an atmosphere of 50 ° C. and 90% for 24 hours, TH-PMD manufactured by Okura Electric Co., Ltd.
And printing was performed at an applied energy of -0.34 mJ / dot using a Macbeth densitometer (using an amber filter). [Background fog] The uncolored portion of the sample was left in a room at 23 ° C and 50% for 1 week, and then the background color was visually observed. ○ Not generated × Generated Quality test results are shown in the table.

[0033]

[Table 1]

[0034]

[Table 2]

As is clear from the above results, Examples 1 to 4 of the present invention show that color sensitivity, whiteness, ground color preservability, and reprintability (printing ability after being left under high temperature and high humidity) are improved. Excellent quality. On the other hand, Comparative Example 1 using a developer other than those specified in the present invention, Comparative Example 2 using a compound other than the compound represented by the general formula (2), and a sensitizer dispersion were not blended. For Comparative Example 3, sufficient quality cannot be obtained.

[0036]

The heat-sensitive recording material of the present invention has high coloring sensitivity,
Further, even if stored for a long period of time, there is little decrease in coloring ability, and there is no occurrence of ground color over time, so that the thermosensitive recording medium can maintain high quality for a long period of time.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshihide Kimura 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 2H026 AA07 BB25 DD02 DD45

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive coloring layer containing a colorless or light-colored basic colorless dye and an organic developer as main components, wherein the thermosensitive coloring layer comprises an organic developer. A heat-sensitive recording material comprising at least one sulfonamide phenol derivative represented by the following general formula (1), and further containing a compound represented by the following general formula (2). Embedded image (X is a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, an alkoxyl group, or a nitro group, and R _{1 to} R ₅ are a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, an alkenyl group. , An alkoxyl group, a cycloalkoxyl group, an alkenyloxy group, a nitro group, or an acyl group, wherein R ₁ and R ₂ or R ₂
And R ₃ may form an aromatic ring. ) (In the formula, R ₆ represents H or CH ₃ , and R ₇ represents H or an electron withdrawing group.)