JP2002137550A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium which shows outstanding color development sensitivity, excellent whiteness, ground color and image conservation properties and no decoloring when the medium comes into contact with body fat. SOLUTION: The chemical recording medium is characterized in that a thermal color development layer contains at least one kind selected from sulfonamide phenol derivatives represented by the described general formula (1) as an organic developer and further contains a sulfonamide compound and 1,2- bis(phenoxymethyl) benzene represented by the described general formula (2). (In the formula (1), X is a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, an alkoxy group or a nitro group; R1-R5 are the hydrogen atom, the halogen atom, the alkyl group, a cycloalkyl group, an alalkyl group, an aryl group, an alkenyl group, the alkoxyl group, a cycloalkoxyl group, an alkenyloxy group, the nitro group or an acyl group; and R1 and R2 or R2 and R3 may form an aromatic ring.) (In the formula (2), R6 is a 1-6C alkyl group or an electron attraction group; and n is an integer of 0-2).

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. When a sensitizer is used, the sensitizer is first melted when heated, and the dye and the developer dissolve into each other at the molecular level to induce a color-forming reaction. It is important to consider dyes and color developers.

[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]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium having high color sensitivity, good whiteness and good ground color preservability, and excellent storage stability of a color image.

[0006]

SUMMARY OF THE INVENTION As a result of intensive studies by the present inventors, as a result of the present inventors, 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. The thermosensitive coloring layer contains at least one sulfonamide phenol derivative represented by the following general formula (1) as an organic developer, and further comprises a sulfonamide compound represented by the following general formula (2) and 1,2 -Bis (phenoxymethyl) benzene.

[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 an alkyl group having 1 to ₆ carbon atoms or an electron withdrawing group, and n represents an integer of 0 to 2.)

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 sulfonamide compound represented by the general formula (2) and 1,2-bis (phenoxymethyl) benzene used in the present invention are both compounds having a sensitizing effect. It has been found that a thermosensitive recording medium having extremely high color development sensitivity and excellent in whiteness, ground color and image storability can be obtained by combining with an organic developer represented by the formula (1). Although the reason for this has not been clearly elucidated, since the developer of the general formula (1), the compound of the general formula (2) and 1,2-bis (phenoxymethyl) benzene have good compatibility, the coloring sensitivity and It is considered that this contributes to improvement of image stability. Further, the sulfonamide phenol derivative of the general formula (1) has a relatively low solubility in water, which is considered to maintain a good ground color.

[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), a general formula (2), or 1,2-bis (phenoxymethyl) benzene is dispersed together with a binder is mixed,
A thermosensitive recording layer of the present invention can be produced by preparing a thermosensitive coloring layer coating solution by adding a filler and other necessary additives, and coating and drying the coating on a substrate to form a thermosensitive coloring layer.

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 N-benzenesulfonyl-p-aminophenol N- (p-toluenesulfonyl) -m-aminophenol N- ( p-toluenesulfonyl) -p-aminophenol N- (2,4-dimethylbenzenesulfonyl) -m-aminophenol N- (2,4-dimethylbenzenesulfonyl) -p-aminophenol N- (p-chlorobenzenesulfonyl) ) -M-aminophenol N- (p-chlorobenzenesulfonyl) -p-aminophenol N- (α-naphthalenesulfonyl) -m-aminophenol N- (α-naphthalenesulfonyl) -p-aminophenol N- (β -Naphthalenesulfonyl) -m-aminophenol N- (β- Lid Ren sulfonylamino)-p-aminophenol, and the like, but not limited thereto.
Among them, N-benzenesulfonyl-p-aminophenol is most preferably used because of its excellent availability and sensitivity. These developers may be used alone or in combination of two or more.

The present invention contains a sulfonamide compound represented by the general formula (2). Content is organic developer 1
The use of 0.1 to 2 parts by weight per part is preferable because the sensitivity is good. In the general formula (2), R ₆ may be any substituent that does not inhibit the sensitizing effect, and examples of such a substituent include an alkyl group having 1 to 6 carbon atoms or an electron withdrawing group such as a halogen atom. Can be Specific examples of the compound represented by the general formula (2) include the following 2-1 to 2-30, but are not limited thereto. Among them, (2-2) and (2-4) are preferably used because the effect when used with the organic developer represented by the general formula (1) is good. These compounds may be used alone or in combination of two or more.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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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 papers can be used. Compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical colorless to light-colored 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) fluorane 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) fluoran 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-
Anilinofluoran 3-di-n-pentylamino-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)
Aminoanilinofluoran 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. Such sensitizers include ethylene bisamide, montanic acid wax, polyethylene wax,
1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-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-chlorobenzyl)
Methylbenzyl), dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-
Examples thereof include diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, and 4- (m-methylphenoxymethyl) biphenyl, but are not particularly limited thereto. 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, ethyl cellulose, cellulose derivatives such as acetyl cellulose,
Styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylate, polyvinyl butyl laral, polystyrene and their copolymers,
Examples thereof include polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumaro resin.
These polymer substances are used by dissolving them in solvents such as water, alcohols, ketones, esters, and hydrocarbons.Also, they are used in the form of emulsified or dispersed in water or other media in the form of a paste. 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 within a range which does not impair the desired effect on the above-mentioned problems. -Methylphenol), 2,2 '
-Di-tert-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-tert-butylphenylbutane, 4-benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) diphenylsulfone, epoxy resin,
It is also possible to add a diphenylsulfone cross-linked compound described in JP-A-29969.

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 color 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 the 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.

[0030]

The present invention will be described below with reference to examples.
In addition, in description, a part shows a weight part. [Example 1] Dispersions having the following formulations were prepared in advance for the respective materials of the dye and the developer, and wet milling was performed with a sand grinder until the average particle size became 0.5 μm. <Developer dispersion> N-benzenesulfonyl-p-aminophenol 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts <Dye dispersion> 3-di-n-butylamino-6 Methyl-7-anilinofluoran (ODB2) 3.0 parts 10% aqueous polyvinyl alcohol solution 6.9 parts Water 3.9 parts <1,2-bis (phenoxymethyl) benzene dispersion> 1,2-bis (phenoxy) Methyl) benzene 3.0 parts 10% aqueous polyvinyl alcohol solution 9.4 parts water 5.6 parts <Sulfonamide compound dispersion> (2-4) Compound 3.0 parts 10% aqueous polyvinyl alcohol solution 9.4 parts water 5. 6 copies

The following compositions were mixed to obtain a coating solution for the heat-sensitive layer. 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 liquid ((1-1) compound) 36.0 parts Dye dispersion liquid (ODB2) 13.8 parts 1,2-bis (phenoxymethyl) benzene dispersion liquid 18.0 parts Sulfonamide compound dispersion liquid 18. 0 parts Kaolin clay 50% dispersion 26.0 parts Zinc stearate 30% dispersion 6.7 parts

Example 2 The procedure of Example 1 was repeated except that the amounts of the 1,2-bis (phenoxymethyl) benzene dispersion and the sulfonamide compound dispersion were changed. Thus, a thermosensitive recording medium was obtained. Developer dispersion liquid (compound (1-1)) 36.0 parts Dye dispersion liquid (ODB2) 13.8 parts 1,2-bis (phenoxymethyl) benzene dispersion liquid 36.0 parts Sulfonamide compound dispersion liquid 36. 0 parts Kaolin clay 50% dispersion 26.0 parts Zinc stearate 30% dispersion 6.7 parts

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 2 except that the dispersion of 1,2-bis (phenoxymethyl) benzene was not used.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 2, except that the sulfonamide compound dispersion was not blended.

Comparative Example 3 In Example 1, N-benzenesulfonyl-p-aminophenol in the developer dispersion was replaced with 4,4'-isopropylidene diphenol (BPA).
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the temperature was changed to.

[Coloring sensitivity] TH-PMD manufactured by Okura Electric Co., Ltd.
And the applied energy of 0.2 to the created thermosensitive recording medium.
Printing was performed at 5 mJ / dot and 0.34 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 a sample piece in an uncolored portion was measured by Hunter whiteness (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). [Fingerprint resistance] Using a TH-PMD manufactured by Okura Electric Co., the applied energy of 0.34 mJ / do was applied to the heat-sensitive recording medium prepared.
Printing was performed at t. After printing a fingerprint on the printing part,
% For one month in a room, and then visually evaluated the decoloring condition of the printed portion. ○ Does not disappear at all or hardly disappears and has no practical problem △ Slightly disappears and has practical problem [Long-term image storability] Applying 0.34 mj of energy to a thermosensitive recording medium prepared using TH-PMD manufactured by Okura Electric Co.
After printing at / dot, the sample was left in a room at 23 ° C. and 50% for one month, and then measured with a Macbeth densitometer (using an amber filter).

Table 1 shows the quality test results. In the table,
(1): 0.25 mJ / dot, (2): 0.34 mJ / do
"t" indicates that printing was performed.

[0038]

[Table 1]

As is clear from the above results, Examples 1 and 2 of the present invention are excellent in color sensitivity, whiteness, ground color preservation and image preservation, and fingerprint resistance. In contrast, the sulfonamide compound represented by the general formula (2) or 1,
In Comparative Examples 1 and 2, which contain only one of 2-bis (phenoxymethyl) benzene, and Comparative Example 3, in which a developer other than that specified in the present invention is used, sufficient quality cannot be obtained.

[0040]

The heat-sensitive recording material of the present invention has high color sensitivity, good whiteness and ground color stability, does not lose its color even when left for a long time or comes into contact with body fat, and preserves images. It is a high quality thermosensitive recording medium with excellent properties.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Kaneko 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 2H026 AA07 BB01 BB25 BB28 DD02 DD12 DD45 DD53 FF01

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive coloring layer containing a colorless or pale-colored basic colorless dye and an organic developer as main components, wherein the thermosensitive coloring layer is an organic developer. Contains at least one sulfonamide phenol derivative represented by the following general formula (1), and further contains a sulfonamide compound represented by the following general formula (2) and 1,2-bis (phenoxymethyl) benzene A heat-sensitive recording material, characterized in that: 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 an alkyl group having 1 to ₆ carbon atoms or an electron withdrawing group, and n represents an integer of 0 to 2.)