JP2002178646A - Heat sensitive recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording body, the color sensitivity of which is high, which has the storage stability of an image such as an excellent resistance against a plasticizer or the like. SOLUTION: This heat sensitive recording body includes a urea urethane compound represented by formula (1) as a developer. Further, the recording body includes 0.01 to 0.9 parts of a compound represented by formula (2) to one part of the developer. Furthermore, the recording body includes 0.01 to 2 parts of a compound represented by formula (3) or (4) to one part of the developer. In formula (2), R1 represents a non-substituted or substituted 1-4C alkyl group, an aralkyl group, a phenyl group or a hydrogen atom. In formula (3), R2 represents a 1-6C alkyl group or an electron-attracting group and (u) represents an integer having a value of zero to two. In formula (4), R3 and R4 respectively represent a hydrogen atom, a 1-6C alkoxy group or an allyloxy 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 having excellent color development sensitivity and image storage stability.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording material is prepared by grinding and dispersing a colorless or pale-colored basic colorless dye and an organic developer such as a phenol compound into fine particles, and then mixing and dispersing the binder. Filler, sensitivity improver, paint obtained by adding a lubricant and other auxiliaries, paper, synthetic paper, film, coated on a support such as plastic,
Color is formed by an instantaneous chemical reaction due to heating by a thermal head, hot stamp, hot pen, laser light, or the like, and a recorded image is obtained. Thermal recording media are widely used in facsimile machines, computer terminal printers, automatic ticket vending machines, measurement recorders, and the like. In recent years, high-speed printing and high-speed image formation have become possible along with the diversification of recording apparatuses and the advancement of performance, and higher quality is required for the recording sensitivity of a thermosensitive recording medium.

As a method for satisfying this requirement, it has been proposed to use a dye and a developer together with a sensitizer. For example, when the color 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 using a sensitizer,
When heated, the sensitizer first melts, and it dissolves the basic dye and the developer, so that the two are mixed at the molecular level to induce a color-forming reaction. It is important to consider the color developer.

[0004] In particular, when the recording sensitivity is improved by a sensitizer or the like, the storage stability of the recorded image often cannot be maintained. Specifically, a sebum component adheres or a plasticizer (DOP, DOA, etc.) contained in a wrap film such as a PVC film.
Etc.), there still remain disadvantages such as a marked decrease in image density and decoloration. In recent years, with increasing use in fields such as labels where reliability is required for recorded images, high storage stability against plasticizers, fats and oils contained in packaging materials and the like has been achieved. There is a need for the recording materials shown. So far, thermal recording media using various auxiliaries such as various dyes, developers, or storage stabilizers have been proposed, but no satisfactory one has been found.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording medium having a greatly improved recording sensitivity and excellent storage stability of an image.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a thermosensitive recording medium having the above-mentioned performance. As a result, a urea urethane compound was used as a developer, and a hydroxy group-containing diphenyl sulfone was added thereto. skeleton (-C ₆ H ₄ -
SO ₂ -C ₆ H ₄ -) in combination with an aromatic compound having, to obtain excellent heat-sensitive recording material in the recording sensitivity and image stability by combining a compound having more sulfonamide group or a diphenyl sulfone skeleton Successfully, the present invention has been completed. That is, the present invention relates to a heat-sensitive recording medium provided with a heat-sensitive recording layer containing a colorless or light-colored basic colorless dye and an organic color developer as main components on a support, wherein the heat-sensitive recording layer is an organic color developer. A urea urethane compound represented by the following general formula (1), and at least one aromatic compound having a hydroxy group-containing diphenylsulfone skeleton represented by the following general formula (2). A thermosensitive recording medium comprising at least one compound having a sulfonamide represented by the formula (3) or a compound having a diphenylsulfone skeleton represented by the formula (4). In the present invention, the use ratio of the following general formula (1) and the following general formulas (2), (3) or (4) is not particularly limited, but is represented by the following general formula (2), for example. The compound is used in an amount of 0.01 to 0.9 based on 1 part of the compound represented by the general formula (1).
It is preferable to contain at least one kind in a proportion of parts,
Further, the compound represented by the following general formula (3) or (4) is added in an amount of 0.01 to 1 part of the compound represented by the general formula (1).
It is preferable to contain at least one kind in a proportion of 2 to 2 parts.

[0007]

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[0008]

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(In the formula, R ₁ represents an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms, an aralkyl group, a phenyl group or a hydrogen atom.)

[0010]

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(Wherein R ₂ represents an alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group, and u represents an integer of 0 to 2).

[0012]

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(Wherein R ₃ and R _{4 are} hydrogen atoms and have 1 to 1 carbon atoms)
6 represents an alkoxy group or an allyloxy group. In the present invention, at least one urea urethane compound represented by the general formula (1) is used as an organic developer. Specific examples of the compound represented by the general formula (1) are given below.

[0014]

Embedded image The present invention also contains at least one compound represented by the general formula (2). In the general formula (2), R ₁ may be any substituent that does not inhibit image stability and heat resistance. Examples of such a substituent include an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms, Examples include an aralkyl group, a phenyl group and a hydrogen atom. Specific examples of the compound represented by Formula (2) include (2-1) to (2-11) shown below, but are not limited thereto. The compound represented by the general formula (2) also has a color developing ability, but when used in combination with the color developer represented by the general formula (1), an effect of improving a sensitizing effect and image storability is obtained. . Although the reason for this is not clear, it is considered that both have a very high compatibility because they have a diphenylsulfone skeleton.

[0015]

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[0016]

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[0017]

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In the present invention, when the content of the compound represented by the general formula (2) is less than 0.01 part with respect to 1 part of the color developing agent represented by the general formula (1), sufficient color formation is achieved. When the sensitivity is not obtained and the content is more than 0.9 part per 1 part of the developer, sufficient image stability cannot be obtained. Therefore, it is desirable to use the compound represented by the general formula (2) at a ratio of 0.01 to 0.9 with respect to 1 part of the developer represented by the general formula (1). In the present invention, at least one compound represented by the general formula (3) or (4) is further used. By containing the compound represented by the general formula (3) or (4), a high sensitizing effect can be obtained. The reason why these compounds are effective as sensitizers is that any of these compounds has a sulfone skeleton (—SO ₂ —) in the structure, and therefore, the compound represented by the general formula (1) or the general formula (2) It is considered that the compatibility is extremely good.

In the general formula (3), R ₂ may be any substituent which does not inhibit the sensitizing effect, and examples of such a substituent include a halogen atom and an alkyl group having 1 to 6 carbon atoms. . Specific examples of the compound represented by formula (3) are shown below (3-1) to (3-30).
But are not limited to these.

[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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In the general formula (4), R ₃ and R ₄
May be any substituent that does not inhibit the sensitizing effect. Examples of such a substituent include an alkoxy group having 1 to 6 carbon atoms or an allyloxy group. Specific examples of the compound represented by the general formula (4) are shown below (4-
Examples 1) to (4-9) include, but are not limited to:

[0026]

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In the present invention, the content of the compound represented by the general formula (3) or (4) is less than 0.01 part based on 1 part of the developer represented by the general formula (1). In the case of (1), the sensitizing effect is not sufficient, and when more than 2 parts are contained per 1 part of the developer, a sufficient color density cannot be obtained. Therefore, the compound represented by the general formula (3) or (4) is added in an amount of 0.0 to 1 part of the developer represented by the general formula (1).
It is desirable to use 1 to 2 parts.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a thermosensitive recording medium is prepared by dispersing a colorless or light-colored basic dye and a developer together with a binder, and if necessary, sensitizing agents, fillers, ultraviolet absorbers, water-proofing agents, and the like. A paint is prepared by adding an auxiliary agent such as an antifoaming agent, and is applied on a support and dried.
As the colorless or light-colored basic dye used in the heat-sensitive recording medium of the present invention, any known dyes in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and there is no particular limitation. Preference is given to methane compounds, fluoran compounds, fluorene compounds, divinyl compounds and the like. 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 [also known as malachite green] Lactone)

<Fluoran Leuco Dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethylanilino ) 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-methyl-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-octyl Anilinofluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl-7-dibenzylanilinofur Oran 3-diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino-6 -Ethoxyethyl-7-anilinofluoran 3-diethylamino-7-methylfluoran 3-diethylamino-7-chlorofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (O-chloroanilino) fluoran 3-diethyla No-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-dibutylamino-6-methyl-7- (p-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl -7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6-methyl-chlorofluoran 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro- 7-anilinofluoran 3-dibutylamino-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- -n- pentylamino-6-methyl -7- (p-
Chloroanilino) fluoran 3-n-dipentylamino-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-anilinofluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofuran Oran 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. Examples of such sensitizers 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, 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-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) and 4- (m-methylphenoxymethyl) biphenyl, but are not particularly limited thereto. These sensitizers may be used alone or in combination of two or more.

As the binder used in the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, 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 macromolecules are water, alcohol, ketone,
In addition to dissolving in solvents such as esters and hydrocarbons,
It is used in a state of being emulsified or dispersed in water or another medium in the form of a paste, and may be used in combination depending on required quality.

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-butylphenyl) butane and the like can also be added. Examples of the filler used in the present invention include inorganic or organic fillers such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. In addition, release agents such as fatty acid metal salts, lubricants such as waxes, benzophenone-based and triazole-based ultraviolet absorbers, waterproofing 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)
0.1 to 2 parts of a basic colorless dye, 0.01 to 2 parts of a compound represented by formula (2), and
Alternatively, 0.01 to 2 parts of the compound represented by (4) and 0.5 to 4 parts of a filler are used, and the binder is 5 to 2 parts in the total solid content.
5% is appropriate. 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, and the like. Further, an overcoat layer of a polymer substance or the like can be provided on the heat-sensitive recording layer for the purpose of enhancing the storage stability.
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.
Further, an undercoat layer of a polymer substance or the like containing a filler may be provided below the heat-sensitive layer for the purpose of increasing the coloring sensitivity.

[0038]

EXAMPLES The thermosensitive recording medium of the present invention will be described below with reference to examples. In the description, parts and% represent parts by weight and% by weight, respectively, unless otherwise specified. [Examples 1 to 4] In Examples 1 to 4, compounds (1-1) (Examples 1 and 3) were used as a color developer in the thermosensitive recording medium of the present invention.
4), (1-2) (Example 2), 3-dibutylamino-6-methyl-7-anilinofluoran (ODB-2) (Examples 1 and 2) as a basic colorless dye, 3-diethylamino -6-methyl-7-anilinofluoran (OD
B) (Example 3), 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran (S-
205) (Example 4), Compound (2-2) as a compound represented by the general formula (2) (hereinafter referred to as “color developing aid”)
As a compound represented by the general formula (3) (hereinafter referred to as a "sensitizer" together with a compound represented by the general formula (4)),
This is an example using 2). Separately, a developer dispersion (solution A), a basic colorless dye dispersion (solution B), a developer aid dispersion (solution C), and a sensitizer dispersion (solution D) having the following composition are separately sand-sanded. The wet grinding was performed until the average particle diameter became 1 micron. Liquid A (Developer dispersion liquid) Developer 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid B (basic colorless dye dispersion liquid) 2.0 parts 10% aqueous polyvinyl alcohol solution 4 2.6 parts Water 2.6 parts Liquid C (color developing aid dispersion) Compound (2-2) 2.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid D (sensitizer dispersion liquid) ) Compound (3-2) 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts Next, a dispersion was mixed and stirred at the following ratio to prepare a coating liquid. Liquid A (color developer dispersion) 36.0 parts Liquid B (basic colorless dye dispersion) 9.2 parts Liquid C (color developer auxiliary [compound (2-2)] dispersion) 32.0 parts D Liquid (sensitizer [Compound (3-2)] dispersion) 36.0 parts Kaolin clay (50% dispersion) 12.0 parts After applying each of the above coating solutions to one surface of a 50 g / m ² base paper The sheet was processed by a super calender so that the smoothness became 500 to 600 seconds, to obtain a thermosensitive recording medium having a coating amount of 6.0 g / m ² .

Examples 5 to 9 In Examples 5 to 9, the urea urethane compound (1-1) (Examples 5 to 9) was used as a developer.
9), ODB-2 as a basic colorless dye (Examples 5 to 5)
9), Compound (2-5) (Example 5) as a color developing aid,
(2-6) (Example 6), (2-2) (Examples 7 to 10)
9), Compound (3-2) as a sensitizer (Example 5,
6), (3-4) (Example 7), (4-1) (Example 8), and (4-8) (Example 9). A basic colorless dye dispersion and a color developing aid dispersion were treated in the same manner as in Examples 1 to 4. Dispersion of developer (E
Liquid), a basic colorless dye dispersion (solution F), a color developing aid dispersion (solution G), and a sensitizer dispersion (solution H), respectively, using a sand grinder until the average particle diameter is 1 micron. Crushing was performed. Solution E (Developer dispersion) Developer 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Solution F (basic colorless dye dispersion) 2.0 parts 10% aqueous polyvinyl alcohol solution 4 2.6 parts Water 2.6 parts G solution (color developing aid dispersion) Compound (2-2) 2.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts H solution (sensitizer dispersion liquid) ) Compound (3-2) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Next, the dispersion was mixed and stirred at the following ratio to prepare a coating solution. E liquid (developer dispersion liquid) 36.0 parts F liquid (basic colorless dye [ODB-2] dispersion liquid) 9.2 parts G liquid (developer auxiliary dispersion liquid) 32.0 parts H liquid (increase Sensitizer dispersion) 36.0 parts Kaolin clay (50% dispersion) 12.0 parts After applying each of the above coating liquids to one side of a base paper of 50 g / m ² , drying is performed, and the sheet is subjected to supercalendering. The coating was processed to have a smoothness of 500 to 600 seconds to obtain a thermosensitive recording medium having a coating amount of 6.0 g / m ² .

Comparative Example 1 The same operation as in Example 1 was performed. However, the dispersion D was not mixed in the formation of the recording layer. Comparative Example 2 The same operation as in Example 1 was performed. However, the dispersion C was not mixed in the formation of the recording layer. Comparative Example 3 The same operation as in Example 1 was performed. However, in preparing the dispersion D, p was used instead of the compound (2-2).
-Benzylbiphenyl (PBB) was used. <Evaluation of thermosensitive recording medium> The applied thermal energy of the produced thermosensitive recording medium was 0.30 and 0.41 mj using TH-PMD (a thermal recording paper printing tester manufactured by Okura Electric Co., Ltd. and a thermal head manufactured by Kyocera Corporation). / Dot. The recording density of the recording section was measured with a Macbeth densitometer (RD-914, using an amber filter) (see Tables 1 and 2). After the plasticizer resistance test, the densities of the recorded portion and the unrecorded portion were measured with a Macbeth densitometer. <Evaluation of plasticizer resistance> A vinyl chloride wrap (Mitsui Toatsu High Wrap KMA) was wrapped around a paper tube in a single layer, and the thermosensitive recording medium recorded by the printer (0.41 mj / dot) was attached thereon, and furthermore, After a triple wrap of PVC wrap was left at 40 ° C. for 24 hours, the Macbeth densities of the recorded portion and the unrecorded portion were measured (see Tables 1 and 2).

[0041]

[Table 1]

[0042]

[Table 2]

As is clear from Tables 1 and 2,
When the compound represented by the general formula (1) is used as a developer, the compound represented by the general formula (2) is used in combination, and the compound represented by the general formula (3) or (4) is further used in combination. Thereby, high recording sensitivity and image storability are exhibited. On the other hand, Comparative Examples 1 and 3 in which the compound of the general formula (3) or (4) was not used together had a recording sensitivity, particularly in a low energy region (0.3
The recording sensitivity at 0 mj / dot) was low, and Comparative Example 2 in which the compound of the general formula (2) was not used also had poor image storability.

[0044]

The heat-sensitive recording material of the present invention comprises a compound represented by the general formula (2) when the diphenylsulfone cross-linked compound represented by the general formula (1) is used as a color developer. Further, by containing the compound represented by the general formula (3) or (4), the color development sensitivity is high, the recorded image is good, and the image stability such as plasticizer resistance is excellent.

 ────────────────────────────────────────────────── ─── Continuing 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 BB24 DD02 DD12 DD45

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support having thereon a heat-sensitive recording layer containing a colorless or light-colored basic colorless dye and an organic color developer as main components, wherein the heat-sensitive recording layer comprises an organic color developer. Contains a urea urethane compound represented by the following general formula (1) and contains at least one compound represented by the following general formula (2), and further contains the following general formula (3)
Alternatively, a thermosensitive recording medium containing at least one compound represented by (4). Embedded image Embedded image (In the formula, R ₁ represents an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms, an aralkyl group, a phenyl group, or a hydrogen atom.) (In the formula, R ₂ represents an alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group, and u represents an integer of 0 to 2.) (In the formula, R ₃ and R ₄ represent a hydrogen atom, an alkoxy group having 1 to 6 carbon atoms, or an allyloxy group.)