JP2003072246A - Heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium having excellent recording sensitivity, thermal fogging resistance, wet fogging resistance of an unrecorded part and preservability of a recorded part. SOLUTION: The heat-sensitive recording medium comprises a heat-sensitive recording layer containing a leuco dye and a colorant on a support. In this medium, as the colorant, at least a 4,4'-bis[(4-methyl-3- phenoxycarbonylaminophenyl-ureido)]diphenylsulone is used. In the medium, as a fogging inhibitor, an organic nitrogen-containing compound such as a tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxy late or the like is contained.

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 utilizing a color-forming reaction between a leuco dye and a coloring agent.

[0002]

2. Description of the Related Art A thermosensitive recording medium utilizing a coloring reaction between a leuco dye and a color developing agent is relatively inexpensive, a recording device is compact, and maintenance thereof is easy. , And is used in a wide range of fields as a recording medium for other purposes.

Along with the expansion of the field of use of the thermal recording material, the operating environment of the thermal recording material has come to be used under severe conditions of 70 to 80 ° C. Therefore, there is a demand for a black thermosensitive recording medium which is less likely to cause background fog even when exposed to a thermal recording medium under such conditions, has excellent storage stability in the recording area, and has excellent recording sensitivity.

A heat-sensitive recording material containing 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone as a coloring agent having a good storage stability in the recording area is available. International Patent Publication WO2000-1
Although described in 4058, there is a problem that background fog occurs under the condition of 70 to 80 ° C.

It is described in JP-A-56-93589 that an antifoggant such as an organic nitrogen-containing wing compound is contained in a heat-sensitive recording material in order to suppress background fog generated in the heat-sensitive recording layer. , The recording density may decrease.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which is excellent in recording sensitivity, heat-resistant background fog resistance in unrecorded areas, wet-surface background fog resistance, and storage stability of recorded areas. .

[0007]

In a heat-sensitive recording material having a heat-sensitive recording layer containing a leuco dye and a color-developing agent on a support, one means for solving the above-mentioned problems is to use at least a color-developing agent. 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenyl sulfone is used, and an organic nitrogen-containing compound is contained in the heat-sensitive recording material as an antifoggant.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a thermosensitive recording medium having a thermosensitive recording layer containing a leuco dye and a coloring agent,
4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenyl sulfone was used as a fog-preventing agent in a heat-sensitive recording material, and a specific nitrogen-containing compound (hereinafter, referred to as an organic compound) was used. Nitrogen-containing antifoggant) is contained, and the amount of the specific colorant and the organic nitrogen-containing antifoggant is not particularly limited, but the specific colorant is used in the heat-sensitive recording layer. On the other hand, it is preferably about 10 to 70% by mass, more preferably 2
The amount of the organic nitrogen-containing antifoggant is preferably about 1 to 30% by mass, and more preferably about 5 to 25% by mass, based on the specific coloring agent.

When the content of the organic nitrogen-containing antifoggant is less than 1% by mass based on the specific color-developing agent, the heat-resistant surface fog property under the conditions of 70 to 80 ° C. and the wet surface fog property under the conditions of 40 ° C. and 90% RH. The effect of improving the
If it exceeds 30% by mass, the recording density may decrease.

An organic nitrogen-containing antifoggant is contained in the heat-sensitive recording material for preventing fogging of the heat-sensitive recording layer, but the location of the content is not particularly limited. For example, the support, the heat-sensitive recording layer, the support and the heat-sensitive recording material. An undercoat layer provided between the thermosensitive recording layer and the undercoat layer, or a protective layer provided on the thermosensitive recording layer. Of these, the heat sensitive recording layer is preferable.

The organic nitrogen-containing antifoggant is preferably hydrophobic and crystalline, for example, tetrakis (1,
2,2,6,6-Pentamethyl-4-piperidyl)-
1,2,3,4-butanetetracarboxylate, bis (2,2,6,6, -tetramethyl-4-piperidyl)
Hindered amine compounds such as sebacate, N, N'-
Aroma such as diphenylphthalamide, N, N'-diphenylterephthalamide, N, N'-dicyclohexylisophthalamide, (N-methyl-N'-phenyl) isophthalamide, bis (N-methyl-N-phenyl) isophthalamide Group amide compounds, diphenylguanidine,
Examples thereof include aromatic guanidine compounds such as triphenylguanidine, and higher aliphatic amine compounds such as stearylamine and behenylamine. Of these, hindered amine compounds are preferable.

As the leuco dye contained in the heat-sensitive recording layer, for example, various known leuco dyes can be used. Specific examples of such a coil dye include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 3- (4-diethylamino-2-methylphenyl).
-3- (4-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (N-ethyl-Np-tolyl)
Amino-7-N-methylanilinofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3- ( N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3
-Diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6
-Methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6- Methyl-7-anilinofluorane, 3
-Diethylamino-6-chloro-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3,3-bis [ 1- (4-methoxyphenyl)
-1- (4-dimethylaminophenyl) ethylene-2-
Il] -4,5,6,7-tetrachlorophthalide, 3-
p- (p-Dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluorane, 3,6-bis (dimethyl) Amino) fluorene-9-
Spiro-3 '-(6'-dimethylamino) phthalide and the like can be mentioned.

Of course, the present invention is not limited to these,
Also, two or more kinds can be used in combination. The amount of the leuco dye used is not limited because it varies depending on the coloring agent used, but it is about 5 to 35% by mass relative to the heat-sensitive recording layer.

The heat-sensitive recording layer may contain a sensitizer for improving the recording sensitivity and a storage stability improving agent for further improving the storage stability of the recording area. Specific examples of the sensitizer include known 2-naphthylbenadyl ether, parabenzyl biphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate, and the like.
1,2-diphenoxyethane, 1,2-di (m-tolyloxy) ethane, 1,2-bis (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, metaterphenyl, diphenyl, 2-
(2'-hydroxy-5'-methylphenyl) benzotriazole, benzophenone, etc. can be mentioned.

Specific examples of the storability improver include, for example, known 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3.
-Tris (2-methyl-4-hydroxy-5-tert)
-Butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 '-[1,4-phenylenebis (1-methylethylidene)] bisphenol, And 4,4'-
[1,3-Phenylenebis (1-methylethylidene)]
Phenolic compounds such as bisphenol, 4-benzyloxyphenyl-4 '-(2-methyl-2,3-epoxypropyloxy) phenyl sulfone, 4- (2-
Epoxy compounds such as methyl-1,2-epoxyethyl) diphenylsulfone and 4- (2-ethyl-1,2-epoxyethyl) diphenylsulfone, and 1,3,5-tris (2,6-dimethylbenzyl-) 3-
Examples thereof include isocyanuric acid compounds such as hydroxy-4-tert-butyl) isocyanuric acid.

The sensitizer and the storability improver are not limited to these, and if necessary, two or more kinds of compounds can be used in combination. The amounts of these sensitizer and storability improver used are not particularly limited, but it is desirable to use 0.1 to 4 parts by mass or less with respect to 1 part by mass of each specific leuco dye.

The heat-sensitive recording layer contains a specific coloring agent, but as long as the desired effect of the present invention is not impaired,
Other coloring agents can be included.

Other coloring agents include N- (p-toluenesulfonyl) -p-aminophenol and 4,4 '.
-Cyclohexylidene diphenol, 2,2-bis (4
-Hydroxyphenyl) -4-methylpentane, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 2,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfone, 4-
Hydroxy-4′-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4-bis (phenylsulfonyl) phenol, 4-hydroxy-4′-methyldiphenyl sulfone, bis (p-hydroxy) Phenyl) butyl acetate, bis (p-hydroxyphenyl) methyl acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane,
Phenolic compounds such as 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene and 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene , Np-tolylsulfonyl-
N'-phenylurea, Np-tolylsulfonyl-
N'-p-butoxyphenylurea, N-p-tolylsulfonyl-N'-3- (p-tolylsulfonyloxy)
Those having a _-SO 2 NH- bond in the molecule such as phenylurea, p- chlorobenzoic acid zinc, 4- [2-(p-methoxyphenoxy) ethyloxy] zinc salicylate, 4
Examples thereof include zinc salts of aromatic carboxylic acids such as zinc [-(3- (p-tolylsulfonyl) propyloxy] salicylate and 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid.

Among them, the combination with at least one selected from 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenylsulfone and 2,4'-dihydroxydiphenylsulfone is recorded. It is preferable because it enhances the sensitivity and the storage stability of the recording portion. The amount of such a coloring agent used is preferably about 10 to 200% by mass, and more preferably about 15 to 100% by mass, based on the specific coloring agent.

The heat-sensitive recording layer generally uses water as a medium, and a specific colorant, an organic nitrogen antifoggant, a leuco dye, a sensitizer, and a preservative improving agent are mixed in a ball mill, attritor, sand mill, etc. A coating liquid for a heat-sensitive recording layer obtained by pulverizing with a pulverizer together or separately to have an average particle diameter of about 0.1 to 3 μm, and then mixing and stirring the adhesive and, if necessary, the following auxiliaries. It is obtained by coating and drying on a support.

The type and shape of the support used in the present invention,
There is no particular limitation on the size, and for example, the thickness is 30 to 3
Fine paper (acidic paper, neutral paper) of about 00 μm, medium quality paper, coated paper, art paper, cast coated paper, glassine paper, resin laminated paper, polyolefin synthetic paper, synthetic fiber paper, non-woven fabric, synthetic resin film, etc. Besides, various transparent supports and the like can be appropriately selected and used.

Specific examples of the adhesive contained in the coating liquid for the heat-sensitive recording layer include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diacetone amide modified polyvinyl alcohol. , Carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene /
Examples thereof include acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, urethane resin latex, acrylic resin latex, styrene / butadiene resin latex and the like. The amount of the adhesive used is about 5 to 30% by weight based on the total solid content of the thermosensitive recording layer.

Further, various auxiliary agents can be added to the coating liquid for the heat-sensitive recording layer, if necessary. For example, kaolin,
Light (heavy) calcium carbonate, calcined kaolin, titanium oxide, magnesium carbonate, aluminum hydroxide, amorphous silica, pigments such as urea / formalin resin filler, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate Sodium, surfactants such as fatty acid metal salts, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, adipic dihydrazide, glyoxal, boric acid, dialdehyde starch, methylol urea, Examples thereof include cross-linking agents such as polyamidoamine / epichlorohydrin resins, defoaming agents, coloring dyes, ultraviolet absorbers and fluorescent dyes.

A protective layer may be provided on the heat-sensitive recording layer in order to improve the chemical resistance and water resistance of the recording portion or to improve the recording running property. Such a protective layer is formed, for example, by applying a coating liquid for a protective layer, which mainly contains a film-forming adhesive and, if necessary, a pigment, onto the heat-sensitive recording layer and drying it.

The adhesive contained in the coating liquid for the protective layer includes completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol. Such as polyvinyl alcohols, starches,
Hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, diisobutylene / maleic anhydride copolymer salt,
Styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt,
Examples thereof include styrene / butadiene latex, acrylic latex, urethane latex and the like.

Further, an auxiliary agent which can be added to the coating liquid for the heat-sensitive recording layer may be added to the coating liquid for the protective layer. In particular, 2- (2'-hydroxy-3'-dodecyl-5'-
Microcapsules having an average particle size of about 0.5 to 3 μm and containing a penzotreazole-based ultraviolet absorber that is liquid at room temperature, such as methylphenyl) benzotriazole, are preferable. As a wall film material for microcapsules, a polyamide obtained by a polymerization reaction with a polyvalent isocyanate compound /
Polyurethane resins are preferred.

Further, an undercoat layer may be provided between the support and the heat-sensitive recording layer in order to enhance recording sensitivity and recording runnability. The undercoat layer has an oil absorption of 70 ml / 1
The oil-absorbing pigment or organic hollow particles of 00 g or more and the undercoat layer coating liquid containing an adhesive as a main component are applied on a support and dried.

Further, the coating amount of the undercoat layer coating solution 3 to 20 g / m ² by dry weight, preferably 5~12g / m ² approximately,
The coating amount of the heat-sensitive recording layer coating liquid is 2 to 12 g / m on a dry weight basis.
^2, preferably 3 to 7 g / m ² approximately, 0.5 to 10 g / m ² coating amount of the protective layer coating liquid for a dry weight, preferably 1 to
It is about 5 g / m ² .

The coating liquid for each layer is applied by a known coating equipment such as a bar coater, an air knife coater, a blade coater, a gravure coater and a die coater. After coating and drying, each layer can be treated with, for example, a super calender or a gloss calender to give each surface smoothness.

Further, it is possible to provide a protective layer, a pressure-sensitive adhesive layer, a rewetting adhesive layer, a delayed tack type pressure-sensitive adhesive layer, a magnetic recording layer, an ink jet recording layer, a thermal transfer receiving layer, etc. on the back side of the support. is there. In addition, a glossy layer containing resin as the main component with a glossiness of 80% or more is provided on the protective layer, a pattern printing part is provided on each layer with UV ink, flexo ink, etc. Various known techniques in the field of producing a thermal recording material, such as a smoothing treatment using the smoothing method described in (1) above, can be added as necessary.

[0031]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention.
Unless otherwise specified, "part" and "%" indicate "part by mass" and "% by mass", respectively.

Example 1 Preparation of Coating Liquid for Undercoat Layer Baking clay [trade name: Ansilex, oil absorption 110 m
1/100 g, EC company] 40 parts, average particle size 1.0 μ
m organic hollow particles (inner diameter / outer diameter: 0.7, film material: polystyrene) 40% dispersion liquid 100 parts, sodium polyacrylate 40% aqueous solution 1 part, solid concentration 48% styrene-butadiene latex 14 Parts, 50 parts of a 10% aqueous solution of polyvinyl alcohol (saponification degree: 88%, polymerization degree: 1000) and 40 parts of water were mixed and stirred to obtain a coating liquid for undercoat layer.

Preparation of solution A 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenyl sulfone 9
Part, tetrakis (1,2,2,6,6-pentamethyl-
4-piperidyl) -1,2,3,4-butanetetracarboxylate (1 part), a composition containing 5 parts of a 5% aqueous solution of methyl cellulose and 25 parts of water were pulverized with a sand mill until the average particle size became 1.0 μm. , A solution was obtained.

Preparation of solution B 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 10 parts, 5% aqueous solution of methylcellulose 5
Part and 25 parts of water were pulverized with a sand mill until the average particle size became 1.0 μm, and a liquid B was obtained.

Solution C Preparation A composition comprising 2 parts of oxalic acid di-p-chlorobenzyl ester, 8 parts of oxalic acid di-p-methylbenzyl ester, 5 parts of a 5% aqueous solution of methylcellulose, and 25 parts of water was averaged by a sand mill. Crush until the diameter becomes 1.0 μm and
A liquid was obtained.

Preparation of liquid D A composition consisting of 10 parts of 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 5 parts of a 5% aqueous solution of methylcellulose, and 25 parts of water was sand milled to give an average particle size of 1.
It was pulverized to 0 μm to obtain a liquid D.

Preparation of coating liquid for heat-sensitive recording layer A solution 50 parts, solution B 50 parts, solution C 80 parts, solution D 50 parts, polyvinyl alcohol 10% aqueous solution 160 parts, solid concentration 5
20 parts of 0% styrene-butadiene latex, 20 parts of light calcium carbonate and 12.5 parts of a 40% aqueous solution of glyoxal were mixed and stirred to obtain a coating liquid for the heat-sensitive recording layer.

Preparation of coating liquid for protective layer Acetoacetyl-modified polyvinyl alcohol [trade name: Gocefimer Z200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] 10
% Aqueous solution 500 parts, kaolin [trade name: UW-90, E
C company] 80 parts of 50% aqueous dispersion was mixed and stirred to obtain a coating liquid for protective layer.

Preparation of heat-sensitive recording material On one side of a high-quality paper (neutral paper) of 64 g / m ² , the undercoat layer coating solution, the heat-sensitive recording layer coating solution and the protective layer coating solution were respectively applied after drying. A thermosensitive recording medium was obtained by coating and drying so as to obtain 9 g / m ² , 6 g / m ² , and 3 g / m ² , and successively forming an undercoat layer, a thermosensitive recording layer and a protective layer. The obtained thermal recording material was subjected to surface smoothing treatment by super calendar treatment.

Example 2 In the preparation of solution A of Example 1, tetrakis (1,2,2
2,6,6-pentamethyl-4-piperidyl) -1,
Example except that triphenylguanidine was used in place of 1 part of 2,3,4-butanetetracarboxylate
A thermosensitive recording medium was obtained in the same manner as in 1.

Example 3 In the preparation of solution A of Example 1, 4,4'-bis [(4-
Methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone 9 parts and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate
Instead of 1 part, 4,4'-bis [(4-methyl-3-
Phenoxycarbonylaminophenylureido)] diphenylsulfone 8 parts, tetrakis (1,2,2,6,6)
-Pentamethyl-4-piperidyl) -1,2,3,4-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2 parts of butane tetracarboxylate was used.

Example 4 In the preparation of the liquid D of Example 1, 10 parts of 4,4'-dihydroxydiphenyl sulfone was used in place of 10 parts of 1,1-bis (4-hydroxyphenyl) -1-phenylethane. A thermal recording material was obtained in the same manner as in Example 1.

Example 5 In the preparation of liquid D of Example 1, 10 parts of 2,4'-dihydroxydiphenyl sulfone was used in place of 10 parts of 1,1-bis (4-hydroxyphenyl) -1-phenylethane. A thermal recording material was obtained in the same manner as in Example 1.

Example 6 Instead of 2 parts of oxalic acid di-p-chlorobenzyl ester and 8 parts of oxalic acid di-p-methylbenzyl ester in the preparation of the liquid C of Example 1, 2- (2'-hydroxy-) was used.
A thermal recording material was obtained in the same manner as in Example 1 except that 10 parts of 5'-methylphenyl) benzotriazole was used.

Example 7 In the preparation of solution C of Example 1, 1,2- (3-methylphenoxy) was used instead of 2 parts of oxalic acid di-p-chlorobenzyl ester and 8 parts of oxalic acid di-p-methylbenzyl ester. ) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 10 parts of ethane was used.

Example 8 In the preparation of solution A of Example 1, 4,4'-bis [(4-
Methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone 9 parts and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate
Instead of 1 part, 4,4'-bis [(4-methyl-3-
Phenoxycarbonylaminophenylureido)] diphenylsulfone 9.5 parts, tetrakis (1,2,2,2)
6,6-pentamethyl-4-piperidyl) -1,2,
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 0.5 part of 3,4-butanetetracarboxylate was used.

Comparative Example 1 In the preparation of solution A of Example 1, tetrakis (1,2,2
2,6,6-pentamethyl-4-piperidyl) -1,
Example 1 except that 1 part of 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone was used in place of 1 part of 2,3,4-butanetetracarboxylate. A thermosensitive recording medium was obtained in the same manner as described above.

Comparative Example 2 In the preparation of solution A of Example 1, 4,4'-bis [(4-
Methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone 9 parts and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate
Instead of 1 part, 4,4'-bis [(4-methyl-3-
Phenoxycarbonylaminophenylureido)] diphenyl sulfone 5 parts, tetrakis (1,2,2,6,6)
-Pentamethyl-4-piperidyl) -1,2,3,4-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 5 parts of butane tetracarboxylate was used.

Comparative Example 3 In the preparation of solution A of Example 1, 4,4'-bis [(4-
Methyl-3-phenoxycarbonylaminophenylureido)] diphenylsulfone 9 parts and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate
Instead of 1 part, 9 parts of 1,1-bis (4-hydroxyphenyl) -1-phenylethane, tetrakis (1,2,2)
2,6,6-pentamethyl-4-piperidyl) -1,
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 1 part of 2,3,4-butanetetracarboxylate was used.

The thermal recording material thus obtained was subjected to the following evaluation tests, and the results are shown in Table 1.

[Recording Density] Thermal Sensitivity Evaluator [Product Name: TH-
PMD, manufactured by Okura Electric], and applied energy 0.50
Each thermosensitive recording medium was colored at mJ / dot, and the color density of the obtained recorded image was measured by a Macbeth densitometer [trade name: RD-91
4 type, manufactured by Macbeth Co., Ltd.] in visual mode.

[Heat Resistance] The thermosensitive recording medium after recording in the recording density measurement was placed in a dryer at 80 ° C., left for 24 hours, and the optical density of the unrecorded area was measured by the above Macbeth densitometer. The heat resistance was evaluated.

[Humidity resistance] The thermosensitive recording medium after recording in the measurement of recording density was stored for 24 hours in a thermo-hygrostat at 40 ° C. and 90% RH, and the optical density of the unrecorded area was measured by the above Macbeth densitometer. To evaluate the moisture resistance.

[Water resistance] The heat-sensitive recording material after recording in the measurement of recording density was immersed in water at 20 ° C. for 24 hours to dry the heat-sensitive recording material, and then the optical density of the recording portion was changed to the above Macbeth density. Water resistance was evaluated by measuring with a meter.

[Plasticizer resistance] polypropylene pipe (4
Wrap film (trade name: High Wrap KMA-W, manufactured by Mitsui Chemicals) is wound three times on a 0 mmφ tube, and the thermosensitive recording medium after recording for measurement of recording density is placed on top of it and the wrap film is further placed on it. After three-fold winding and leaving it at 40 ° C. for 24 hours, the optical density of the recording portion was measured with the above Macbeth densitometer to evaluate the plasticizer resistance.

[0056]

[Table 1]

As is clear from Table 1, the thermosensitive recording medium of the present invention has excellent effects in recording sensitivity, heat resistance in unrecorded areas and storage stability in recorded areas.

Claims (4)

[Claims] 1. A thermosensitive recording medium having a thermosensitive recording layer containing a leuco dye and a color developing agent on a support, wherein the color developing agent is at least 4,4′-bis [(4-methyl-3-phenoxycarbonyl). Aminophenylureido)] diphenyl sulfone and an organic nitrogen-containing compound as an antifoggant contained in the thermosensitive recording material. 2. The organic nitrogen-containing compound is 5 to 25 relative to 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenylureido)] diphenyl sulfone.
The heat-sensitive recording material according to claim 1, which has a mass%. 3. The heat-sensitive recording material according to claim 1, wherein the organic nitrogen-containing compound is a hindered amine compound. 4. In the heat-sensitive recording layer, 1,
4. At least one selected from 1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4′-dihydroxydiphenylsulfone and 2,4′-dihydroxydiphenylsulfone is contained.
The heat-sensitive recording material described.