JPH0747772A - Thermal recording - Google Patents

Abstract

(57) [Summary] [Object] It is an object of the present invention to provide a heat-sensitive recording material which is excellent in recording sensitivity and storability of a recorded image with respect to chemicals such as oils and fats and plasticizers, and has less background fog. [Structure] In a heat-sensitive recording material containing a colorless or light-colored basic dye and a coloring agent on a support, as a coloring agent, --SO ₂ NHCX-- in the formula, X is an oxygen atom or sulfur. Indicates an atom. ] A thermal recording material containing an aromatic compound having a specific functional group represented by the following and a hydroxydiphenylylphone derivative in the recording layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material which is excellent in color development sensitivity and storability of recorded images and has less background fog.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic color-forming agent to bring both color-forming substances into contact with each other by heat to obtain a recorded image is often used. Are known. Since such a thermosensitive recording medium is relatively inexpensive, the recording device is compact, and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

For example, one of the fields of use thereof is a heat-sensitive recording label for a POS (point of sales) system of a retail store, etc., but with the expansion of the system,
In addition to conventional food labels, which have their missions completed in a short period of time as in the past, the number of applications in which they are attached to products for a long period of time is increasing. However, in such applications, they are often exposed to water, wraps, oil, etc., and are also exposed to indoor light and sunlight for a long period of time, which causes the recorded image (printing) of the heat-sensitive label to fade and the background. A defect that the part turns yellow is recognized, and as a result, the image of the product is significantly impaired. For this reason, it is strongly demanded that the heat-sensitive recording material has storage stability such as water resistance, plasticizer resistance, oil resistance, and light resistance. Further, in recent years, a recording speed of 10 seconds or less for an A4 size in a thermal fax and 120 characters / second or more in a thermal printer has become possible, and there is a further demand for higher sensitivity of a thermal recording material.

However, since a phenol-based coloring agent such as bisphenol A is used in an ordinary heat-sensitive recording material, for example, when human sebum, a solvent, a plasticizer or the like comes into contact with the recording layer, the density of a recorded image is greatly increased. However, there is a defect that the color develops undesirably, or unnecessary coloration called background fog occurs.
For the purpose of improving such defects, various proposals have been made such as a method of providing a protective layer on the recording layer, a method of adding a storability improving agent to the recording layer, and a method of using a new color former. However, none of them are accompanied by new drawbacks or are not sufficiently satisfactory.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material which is excellent in recording sensitivity and storability of a recorded image with respect to chemicals such as oils and fats and plasticizers and has less background fog.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium containing a colorless or light-colored basic dye and a color developing agent on a support as a color developing agent, --SO _{2 in} the molecule. N
HCX- [In the formula, X represents an oxygen atom or a sulfur atom. ] An aromatic compound having a specific functional group represented by,
It was found that the above object can be achieved by incorporating a hydroxydiphenylylphone derivative into the recording layer, and completed the present invention.

[0007]

FUNCTION -SO ₂ NHCX- used in the present invention [wherein, X represents an oxygen atom or a sulfur atom. ] The aromatic compound having a specific functional group represented by
Despite not having a functional group such as an H group or a carboxyl group, it has the ability to develop a color by heating and melting a colorless or light basic dye. It is understood that such coloring ability is due to activation of the amino group adjacent to the sulfonyl group of the above group. In addition, the aforementioned —SO ₂ NHCX— [in the formula, X
Represents an oxygen atom or a sulfur atom. ] In the group-containing compound group, various compounds are conceivable depending on the substituents,
It is preferably one selected from the aromatic compounds represented by the following general formulas [Chemical formula 1], [Chemical formula 2], [Chemical formula 3] or [Chemical formula 4].

[0008]

[Chemical 1]

[0009]

[Chemical 2]

[0010]

[Chemical 3]

[0011]

[Chemical 4]

[However, the general formulas [Chemical formula 1], [Chemical formula 2], [Chemical formula 1]
3] or [Chemical Formula 4], X and Y are respectively
And each independently represent an oxygen atom or a sulfur atom. R₁
Is a lower alkyl group; an aryl group;
Represents an optionally substituted aromatic group. R ₂Is an aralkyl group, ant
Or an alkyl group substituted with an alkyloxy group
Group; alkenyl group; aryl group; aralkyl group; alk
Ruoxy group; aryloxy group; aralkyloxy group;
Alkyl mercapto group; Aryl mercapto group; Aral
Kilmercapto group; alkyloxycarbonyl group; ant
Aroxycarbonyl group; aralkyloxycarbonyl
Group; represents an aromatic group which may be substituted with a halogen atom.
R₃Is a lower alkyl group; an aryl group;
Optionally substituted aromatic group, alkyl group, cycloalkyl
Represents a group or an aralkyl group. R _Four, R_FiveAre each
Independently, hydrogen atom, alkyl group, aralkyl group, aryl
An alkyl group substituted with a ruoxy group, or alkyl
Group; aryl group; aralkyl group; alkyloxy group;
Rukyloxycarbonyl group; Aryloxycarbonyl
Group; aralkyloxycarbonyl group; arylsulfoni
Group; represents an aromatic group which may be substituted with a halogen atom.
A represents a divalent or higher valent group, and n represents an integer of 2 or more.
You ]

-SO ₂ NHCX- [wherein, X represents an oxygen atom or a sulfur atom. The group-containing aromatic compound acts as a coloring agent, and specific examples thereof include the following compounds. N-
(P-Toluenesulfonyl) carbamoyl acid phenyl ester, N- (p-toluenesulfonyl) carbamoyl acid benzyl ester, N- (p-toluenesulfonyl)
Carbamoyl acid 2-phenoxyethyl ester, N-
(P-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid o-biphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid 1-naphthyl ester, N- (p- Toluenesulfonyl) carbamoyl acid 1
-(4-Methoxynaphthyl) ester, N- (p-toluenesulfonyl) carbamoyl acid p-benzyloxycarbonylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-methoxycarbonylphenyl ester, N- (p-toluene) Sulfonyl) carbamoyl acid pn-butoxycarbonylphenyl ester, N
-(P-toluenesulfonyl) carbamoyl acid p-benzyloxyphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-methoxyphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p
-Ethoxyphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-butoxyphenyl ester, N- (benzenesulfonyl) carbamoyl acid p-chlorophenyl ester, N- (p-toluenesulfonyl) carbamoyl acid 2-methoxy-4- Allyl-phenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-methylmercaptophenyl ester, N-
(O-Toluenesulfonyl) carbamoyl acid p-biphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-tolyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-phenoxyphenyl ester, N- (p-toluene) Sulfonyl) carbamoyl acid p
-Benzyl mercaptophenyl ester, N- (1-naphthalenesulfonyl) carbamoyl acid p-benzyl ester, N-benzoylbenzenesulfoamide, N- (o
-Toluoyl) benzenesulfoamide, N- (m-toluoyl) benzenesulfoamide, N- (p-toluoyl) benzenesulfoamide, N- (1-naphthoyl) benzenesulfoamide, N- (2-naphthoyl) benzenesulfoamide , N-benzoyl-o-toluenesulfoamide, N- (o-toluoyl) -o-toluenesulfoamide, N- (m-toluoyl) -o-toluenesulfoamide, N- (p-toluoyl) -o-toluene Sulfamide, N-benzoyl-p-toluenesulfoamide, N
-(O-toluoyl) -p-toluenesulfoamide, N
-(M-toluoyl) -p-toluenesulfoamide, N
-(P-toluoyl) -p-toluenesulfoamide, N
-(3,4-Dimethylbenzoyl) -p-toluenesulfoamide, N- (p-chlorobenzoyl) -p-toluenesulfoamide, N- (o-chlorobenzoyl) -p-
Toluenesulfoamide, N- (2,5-dichlorobenzoyl) -p-toluenesulfoamide, N- (1-naphthoyl) -p-toluenesulfoamide, N- (2-naphthoyl) -p-toluenesulfoamide, N -(3,4-Dimethylbenzoyl) -3,4-dimethylbenzenesulfoamide, N- (benzoyl) -mesitylenesulfoamide, N-benzoyl-p-chlorobenzenesulfoamide, N- (o-chlorobenzoyl) -1- Naphthalenesulfoamide, N- (o-toluoyl) -2-naphthalenesulfoamide, N- (m-toluoyl) -2-naphthalenesulfoamide, N- (p-toluoyl) -2-naphthalenesulfoamide, N-acetyl- Benzenesulfoamide, N-cyclohexanecarbonyl-p-toluenesulfoamide, N-lauro Le -p- toluene sulfonamide, N- myristoyl -p- toluenesulfonyl amido, N
-Palmitoyl-p-toluenesulfoamide, N-stearoyl-p-toluenesulfoamide, N-oleoyl-p-toluenesulfoamide, N-acetylmesitylenesulfoamide, N- (p-toluenesulfonyl) -N '
-Phenylurea (melting point 165 ° C), N- (p-toluenesulfonyl) -N '-(p-methoxyphenyl) urea (melting point 155 ° C), N- (p-toluenesulfonyl)-
N ′-(o-tolyl) urea (melting point 148 ° C.), N- (p
-Toluenesulfonyl) -N '-(m-tolyl) urea (melting point 184 ° C), N- (p-toluenesulfonyl)-
N ′-(p-tolyl) urea (melting point 149 ° C.), N- (p
-Toluenesulfonyl) -N '-(pn-butylphenylurea (melting point 177 ° C), N- (p-toluenesulfonyl) -N', N'-diphenylurea (melting point 159)
C), N- (p-toluenesulfonyl) -N '-(o-
Chlorophenyl) urea (melting point 180 ° C.), N- (p-toluenesulfonyl) -N ′-(m-chlorophenyl) urea (melting point 193 ° C.), N- (p-toluenesulfonyl)
-N '-(2,4-dichlorophenyl) urea, N- (p
-Toluenesulfonyl) -N'-methyl-N'-phenylurea (melting point 155 ° C), N- (p-toluenesulfonyl) -N'-benzylurea (melting point 177 ° C), N- (p
-Toluenesulfonyl) -N '-(1-naphthyl) urea (melting point 124 ° C), N- (p-toluenesulfonyl)-
N '-(1- (2-methylnaphthyl)) urea, N- (benzenesulfonyl) -N'-phenylurea (melting point 153
C), N- (p-chlorobenzenesulfonyl) -N'-
Phenylurea, N- (o-toluenesulfonyl) -N '
-Phenylurea, N- (p-toluenesulfonyl)-
N'-methylurea (melting point 172 ° C), N- (p-toluenesulfonyl) -N'-ethylurea (melting point 141 ° C),
N- (p-toluenesulfonyl) -N '-(2-phenoxyethyl) urea (melting point 191 ° C), N, N'-bis (p-toluenesulfonyl) urea (melting point 155 ° C), N
-(P-toluenesulfonyl) -N'-phenylthiourea, N- (p-toluenesulfonyl) -N '-(o-diphenyl) urea (melting point 148 ° C), N- (p-toluenesulfonyl) -N'- (P-Ethoxycarbonylphenyl) urea, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane, 4,4 '
-Bis (p-toluenesulfonylaminocarbonylamino) -diphenyl ether, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylsulfone and the like. These compounds may be used alone or as a mixture of two or more thereof.

Specific examples of the hydroxydiphenyl sulfone derivative used together with the aromatic compound having the above-mentioned specific functional group include, for example, 4,4'-dihydroxydiphenyl sulfone, 3,4'-dihydroxydiphenyl sulfone,
3,4-dihydroxydiphenyl sulfone, 2,4 '
-Dihydroxydiphenyl sulfone, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone,
2-hydroxy-5-tert-butyl-4'-hydroxydiphenylsulfone, 2-hydroxy-5-tert-amyl-4'-hydroxydiphenylsulfone, 2-hydroxy-5-tert-butyl-3'-methyl-4 ′ -Hydroxydiphenyl sulfone, 4-hydroxy-4 ′
-Isopropoxydiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone and the like can be mentioned. Among these, especially 3,3'-diallyl-
4,4'-dihydroxydiphenyl sulfone and 4
-Hydroxy-4'-isopropoxydiphenyl sulfone is preferable because it is excellent in color development and has very little background fog.

In the present invention, as the colorless or light-colored basic dye used in the recording layer together with the above-mentioned color former, various known colorless or light-colored basic dyes can be mentioned. Specifically, for example, 3, 3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
Diethylamino-7-dibenzylamino-benzo [a]
Fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 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-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) Amino-7- (o-chlorophenylamino) fluorane, 3-diethylamino-7-
(O-Fluorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl-N-isobutyl) amino-7- (p-trifluoro Methyl anilino)
Fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-
N-isobutyl) amino-7- (o-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isoamyl) amino-7- (p-trifluoromethylanilino) fluorane, 3-di (n -Butyl) amino-7-
(M-trifluoromethylanilino) fluorane, 3-
(N-methyl-N-cyclohexyl) amino-7- (o
-Trifluoromethylanilino) fluorane, 3- (N
-Ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino)-
6-methyl-7- (p-toluidino) fluorane, 3-
(N-ethyl-N-furfurylamino) -6-methyl-
7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl-N
-N-propylamino) -6-methyl-7-anilinofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-Pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-Tetrachlorophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-
2-yl] -4,5,6,7-tetrabromophthalide,
3-p- (p-anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '
-(N-cyclohexyl-N-methylamino) -3'-
Methyl spiro [phthalide-3,9'-xanthene-2 '
-Ylamino] phenyl} propane, 3,6, -bis (dimethylamino) fluorene-9-spiro-3'-
(6'-dimethylamino) phthalide and the like can be mentioned. Also, 3- (N-ethyl-N-isobutyl) amino-7-
(P-trifluoromethylanilino) fluorane, 3-
Diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isobutyl)
Amino-7- (o-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isoamyl) amino-
7- (p-trifluoromethylanilino) fluorane,
3-di (n-butyl) amino-7- (m-trifluoromethylanilino) fluorane, 3- (N-methyl-N-
Examples thereof include compounds such as cyclohexyl) amino-7- (o-trifluoromethylanilino) fluorane, which may be used in combination of two or more.

Generally, the content of the basic dye in the recording layer is preferably about 5 to 20% by weight based on the dry weight of the recording layer, and -SO ₂ NHCX- [wherein, X represents an oxygen atom or a sulfur atom. Represent The content of the group-containing compound is generally preferably 5 to 50% by weight. -S
When the content of the O ₂ NHCX-group-containing compound is less than 5% by weight, the color developing ability may be insufficient, and it may be 5
Even if a large amount exceeding 0% by weight is added, the color developing ability is saturated and no further improvement is observed. In the thermal recording material of the present invention,
A sensitizer can be added to the recording layer according to the purpose,
Specific examples of the sensitizer include stearic acid amide,
Methoxycarbonyl-N-stearic acid benzamide,
N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, p- Benzyl benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, oxalic acid-di-
p-methylbenzyl, oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether,
1,2-di (3-methylphenoxy) ethane, 1,2-
Di (4-methylphenoxy) ethane, 1,2-di (4-
Methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1
-(4-Methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenetizide, N-acetoacetyl -P-toluidine, di (β-biphenylethoxy)
Benzene, p-di (vinyloxyethoxy) benzene,
Examples include 1-isopropylphenyl-2-phenylethane and the like. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of about 4 parts by weight or less relative to 1 part by weight of the color developing agent.

Further, a preservative improving agent may be used in combination for the purpose of further enhancing preservability of the recorded image as long as the effect is not impaired. Specific examples of such a storage stability improver include, for example, 2,2'-methylenebis (4-methyl-6).
-Tert-butylphenol), 2,2'-ethylenebis (4-methyl-6-tert-butylphenol) 2,2 '
-Methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4,6-di-tert-
Butylphenol), 2,2'-ethylidene bis (4,
6-di-tert-butylphenol), 2,2'-ethylidenebis (4-methyl-6-tert-butylphenol), 2,2'-ethylidenebis (4-ethyl-6-te)
rt-Butylphenol), 2,2 '-(2,2-propylidene) bis (4,6-di-tert-butylphenol), 2,2'-methylenebis (4-methoxy-6-te)
rt-butylphenol), 2,2'-methylenebis (6
-Tert-butylphenol), 4,4'-thiobis (3
-Methyl-6-tert-butylphenol), 4,4'-
Thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (5-methyl-6-tert-butylphenol), 4,4'-thiobis (2-chloro-)
6-tert-butylphenol), 4,4'-thiobis (2-methoxy-6-tert-butylphenol), 4,
4'-thiobis (2-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-) 5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′-thiobis (3-methylphenol), 4,4′- Dihydroxy-3,3 ', 5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3', 5,5'-
Tetramethyldiphenyl sulfone, 2,2-bis (4-
Hydroxy-3,5-dibromophenyl) propane,
2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,
Hindered phenol compounds such as 5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene,
Epoxy compounds such as 4,4′-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, and bisphenol A type epoxy resin, 1- [α-methyl-α-
(4'-Hydroxyphenyl) ethyl] -4- [α ',
α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-di-tert-
Butylphenyl) sodium phosphate and the like.

In order to prepare a coating liquid for a recording layer containing these substances, water is generally used as a dispersion medium and a basic dye, the aforementioned --SO ₂ NHCX- [, is mixed with a stirrer / pulverizer such as a ball mill, attritor or sand mill. In the formula, X represents an oxygen atom or a sulfur atom. ] A group-containing compound, and further, a sensitizer and the like added as necessary are dispersed together or separately to prepare a coating liquid.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose,
Carboxymethyl cellulose, gelatin, casein, arabic gum, polyvinyl alcohol, diisobutylene
A maleic anhydride copolymer salt, a styrene / maleic anhydride copolymer salt, an ethylene / acrylic acid copolymer salt, a styrene / acrylic acid copolymer salt, a styrene / butadiene copolymer emulsion or the like has a total solid content of 10 -40% by weight, preferably about 15-30% by weight.

Further, various auxiliary agents can be added to the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt and the like. Dispersant, benzophenone type,
Examples thereof include UV absorbers such as triazole type, defoaming agents, fluorescent dyes, and coloring dyes. If necessary, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax,
Lubricants such as ester wax, and inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay can also be added.

In the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally well-known and conventional technique, for example, air knife coating, varibar blade coating, pure blade coating, rod blade coating, It is formed by coating the coating liquid for recording layer on a support and drying it by a suitable coating method such as short dwell coating, curtain coating, or die coating. As the support, paper, plastic film, synthetic paper, non-woven fabric,
It is used by appropriately selecting it from metal deposits and the like. The coating amount of the recording layer coating liquid is 2 to 12 g / m on a dry weight basis.
² , preferably in the range of 3 to 10 g / m ² .

If necessary, a protective layer may be provided on the recording layer and the back side of the thermosensitive recording medium to further improve the storability. Further, in the field of thermosensitive recording medium production, an undercoat layer may be provided on the support, smoothing treatment such as super calendering may be applied after coating each layer, or adhesive treatment may be applied to the back surface of the recording medium to form an adhesive label. Various known techniques can be added as necessary.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized with a sand mill until the average particle size became 1.5 μm or less.

Preparation of solution B 30 parts of N- (p-toluenesulfonyl) carbamoyl acid p-cumylphenyl ester, 5% of methylcellulose
A composition consisting of 5 parts of an aqueous solution and 80 parts of water was pulverized with a sand mill until the average particle size became 2 μm or less.

Preparation of liquid C A composition consisting of 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle diameter became 2 μm or less. did.

Preparation of Solution D 2,4′-dihydroxydiphenylsulfone 20 parts,
A composition consisting of 5 parts of a 5% aqueous solution of methyl cellulose and 55 parts of water was pulverized with a sand mill until the average particle diameter became 2 μm or less.

Formation of Recording Layer 55 parts of A solution, 115 parts of B solution, 80 parts of C solution, 115 parts of D solution, 80 parts of 10% aqueous solution of polyvinyl alcohol, and 35 parts of calcium carbonate were mixed and stirred to obtain a coating. 60 liquid
coating amount after drying on one surface of woodfree paper g / m ² is 6 g / m ²
And dried to form a recording layer to obtain a thermosensitive recording medium.

Example 2 In the preparation of solution B, N- (p
-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester (melting point 120 ° C) instead of N- (p-
Toluenesulfonyl) carbamoyl acid p-benzyloxyphenyl ester (melting point 122 ° C.)
Instead of 4'-dihydroxydiphenyl sulfone,
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenyl sulfone was used.

Example 3 In the preparation of solution B, N- (p
-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester (melting point 120 ° C) instead of N- (o-
Toluoyl) -p-toluenesulfoamide (melting point 112
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (° C.) Was used.

Example 4 In the preparation of solution B, N- (p
-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester (melting point 120 ° C) instead of N- (p-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that toluenesulfonyl) -N '-(p-tolyl) urea (melting point 149 ° C) was used.

Example 5 In the preparation of solution B, N- (p
-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester (melting point 120 ° C) instead of 4,4'-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane was used.

Example 6 In the preparation of solution B, N- (p
-Toluenesulfonyl) carbamoyl acid p-cumylphenyl ester (melting point 120 ° C) instead of 20 parts 4,
Thermal recording material as in Example 1 except that 10 parts of 4'-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane and 10 parts of N- (p-toluenesulfonyl) -N'-phenylurea were used. Got

Example 7 Preparation of Solution E 4-Benzoxyphenyl-4 '-(2-methyl-2,3)
-Epoxy propoxy) phenyl sulfone 20 parts, a composition consisting of 5 parts of a 5% aqueous solution of methyl cellulose, and 55 parts of water was ground by a sand mill until the average particle size became 2 μm or less. A thermosensitive recording medium was obtained in the same manner as in Example 6 except that 50 parts of E liquid was added in forming the recording layer.

[Embodiment 8] In the preparation of liquid D, 2, 4 '
A thermosensitive recording medium was obtained in the same manner as in Example 6 except that bis (3-allyl-4-hydroxyphenyl) sulfone was used instead of 20 parts of dihydroxydiphenylsulfone.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the liquid B was omitted from the formation of the recording layer in Example 1.

[Comparative Example 2] A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the D liquid was omitted in the formation of the recording layer of Example 1.

[Comparative Example 3] In the preparation of solution D, 2,4 '
-4,4 'instead of dihydroxydiphenyl sulfone
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that isopropylidenediphenol was used.

The following 11 quality evaluation tests were performed on the thus obtained 11 kinds of thermal recording materials, and the results are shown in Table 1. [Evaluation] [Color density] The color density of the recorded image obtained by printing with a thermal recording evaluation machine (TH-PMD type, manufactured by Okura Electric Co., Ltd., applied energy 0.4 mJ / dot) was measured by a Macbeth densitometer (manufactured by Macbeth Co.). , RD-9
14R type) was measured in visual mode. [Oil resistance] The thermal recording material after recording by the above method was immersed in salad oil and allowed to stand at room temperature for 8 hours, and the density of the residual image was measured with a Macbeth densitometer (visual mode) to obtain oil resistance. Was evaluated.

[High Temperature and High Humidity Resistance] The thermosensitive recording medium after recording by the above method was heated at 50 ° C. and 75%.
The densities of the afterimages and the densities of the background areas after standing for 24 hours in RH were measured by a Macbeth densitometer (visual mode) to evaluate the high temperature and high humidity resistance.

[0041]

[Table 1]

[0042]

As is clear from the results shown in Table 1, all of the heat-sensitive recording materials of the present invention were heat-sensitive recording materials excellent in color developability and storage stability.

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein --SO ₂ NHCX- [in the formula: , X represents an oxygen atom or a sulfur atom. ] A thermosensitive recording material comprising an aromatic compound having a specific functional group represented by and a hydroxydiphenyl sulfone derivative in the recording layer. 2. An aromatic compound having a specific functional group is one of the following:
In the general formula [Chemical formula 1], [Chemical formula 2], [Chemical formula 3], or [Chemical formula 4]
The thermosensitive recording medium according to claim 1, which is represented. [Chemical 1][Chemical 2][Chemical 3][Chemical 4][However, general formula [Chemical formula 1], [Chemical formula 2], [Chemical formula 3], or
In [Chemical Formula 4], X and Y are independent of each other.
Represents an oxygen atom or a sulfur atom, and R₁Is lower archi
Group; aryl group; aromatic group which may be substituted with a halogen atom
Represents an aromatic group. R ₂Is an aralkyl group, an aryloxy group
An alkyl group substituted with, or an alkyl group; alkene
Group; aryl group; aralkyl group; alkyloxy group;
Aryloxy group; Aralkyloxy group; Alkyl mel
Capto group; Aryl mercapto group; Aralkyl mercap
Group; alkyloxycarbonyl group; aryloxy group
Rubonyl group; aralkyloxycarbonyl group; halogen
Represents an aromatic group which may be substituted with atoms. R₃Is lower
Alkyl group; aryl group; may be substituted with halogen atom
Aromatic group, alkyl group, cycloalkyl group, or
Represents a aralkyl group. R _Four, R_FiveAre independently hydrogen
Atom, alkyl group, aralkyl group, aryloxy group
Substituted alkyl group or alkyl group; aryl
Group; aralkyl group; alkyloxy group; alkyloxy
Carbonyl group; Aryloxycarbonyl group; Aralk
Luoxycarbonyl group; Arylsulfonyl group; Halogen
Represents an aromatic group which may be substituted with a nitrogen atom. Also, A is 2
Represents a group having a valence of at least, and n represents an integer of 2 or more. ]