JPH0890924A - Thermal recording material - Google Patents

Abstract

PURPOSE: To enhance optical character reading aptitude by adding at least one kind of a fluorane derivative being a basic dye, at least one kind of a specific phenothiazine derivative and a specific N-arylsulfonylurea compd. to the recording layer of a thermal recording material. CONSTITUTION: In a thermal recording material wherein a recording layer is provided on a support, at least one kind of a black developing fluorane derivative being a basic dye and at least one kind of a phenothiazine derivative represented by formula I are added to the recording layer so that the phenothiazine derivative becomes 5-100wt.% of the fluorane derivative and an N-arylsulfonylurea compd. represented by formula II is added to the recording layer as a coupler. In the formulae I, II, R1 -R4 are a 1-4C alkyl group, R5 is a hydrogen atom, a halogen atom or a 1-4C alkyl group, R6 is a 1-4C alkyl group or a 1-4C alkoxy group, A is a divalent-tetravalent group, n is an integer of 2-4 and m is an integer of 0-5.

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 reaction between a colorless or light-colored basic dye and a color developing agent, and particularly, it is suitable for optical character reading (OCR) in the wavelength region of 650 to 700 nm. The present invention relates to an excellent thermal recording material.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known in which a color or color reaction between a colorless or pale basic dye and an organic or inorganic coloring agent is used to bring a color image into contact with each other to obtain a recorded image. Has been. Since such a thermal recording material is relatively inexpensive and the recording device is compact and its repair is relatively easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

With the recent diversification of needs, various performances are required for the thermal recording material. As one of them, there is a demand for a thermal recording material for OCR or OMR which has a black color tone and is readable in the wavelength region of 650 to 700 nm. As a method for obtaining such a heat-sensitive recording material, the coating amount of the black-coloring fluoran dye which has been conventionally used is simply increased, or 65 is applied at the time of coloring.
Examples of the dye having a strong absorption at 0 to 700 nm include 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide or 3-di-n-butylamino-6,8,8-trimethyl-8. , 9-dihydro-
A method is used in which (3,2, e) pyridofluorane or the like is used in combination with a black coloring fluorane dye. However, although these methods have OCR suitability immediately after color development, they can be stored under high temperature and high humidity, exposed to light, or stationery such as water-based ink pens, oil-based ink pens, highlighters, vermilion, and glue, office supplies, and hand creams. When touching a cosmetic such as a hair nick, a milky lotion, or a packaging material such as a vinyl chloride film, the recorded image is discolored or the white paper portion is colored, and the OCR suitability is lost. Therefore, the improvement is strongly demanded.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a thermal recording material having excellent suitability for optical character reading (OCR) in the wavelength region of 650 to 700 nm.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a color developing agent. As a dye, at least one black coloring fluoran derivative and at least one phenothiazine derivative represented by the following general formula (1) are contained so that the phenothiazine derivative is 5 to 100% by weight of the fluoran derivative,
Further, they have found that the above-mentioned problems can be solved by containing an N-arylsulfonylurea compound represented by the following general formula (2) or (3) as a color developing agent, and have completed the present invention.

[0006]

[Chemical 5]

[In the general formula (1), R _{1 to} R ₄ each represent a C _{1 to} C ₄ alkyl group, and R ₅ represents a hydrogen atom, a halogen atom, a C _{1 to} C ₄ alkyl group or C ₁
Is a C ₄ -alkoxyl group. ]

[0008]

[Chemical 6]

[In the general formula (2), R ₆ is C _{1 to} C
_{4 represents} an alkyl group, a C ₁ -C ₄ alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group, and A is 2
A valent, trivalent or tetravalent group, n is an integer of 2 to 4 and m is an integer of 0 to 5. ]

[0010]

[Chemical 7]

[In the general formula (3), R ₇ and R ₈ each represent a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group, and p and q Each represents an integer of 0 to 5. ]

[0012]

According to the present invention, a black-colored fluoran derivative and a specific phenothiazine derivative are used together in a specific ratio as a colorless or light-colored basic dye, and a specific N-arylsulfonylurea compound is used as a coloring agent. Therefore, even if exposed to high temperature and high humidity or light for a long time or contact with various chemicals, the suitability for optical character reading (OCR) in the wavelength range of 650 to 700 nm does not deteriorate,
In addition, a black color type thermosensitive recording medium with less background fog can be obtained.

When the amount of the basic dye in the recording layer is increased, the readability for optical characters is naturally improved, but in view of recording sensitivity, yellowing of unrecorded paper upon light exposure, and economy, the basic dye is considered. As the amount of 0.2-1.0g
It is preferable to adjust in the range of / m ² . The amount of the phenothiazine derivative in the recording layer is preferably 5 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on the fluorane dye. When the amount of the phenothiazine derivative in the recording layer is less than 5% by weight, the OCR suitability is lost especially after long-term exposure to light, and when it exceeds 100% by weight, the OCR suitability immediately after color development is lowered, and the temperature and humidity are decreased. Background fogging occurs under the influence of light.

Specific examples of the black coloring fluoran derivative used in the present invention include the followings. 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7
-(M-toluidino) fluorane, 3-diethylamino-6-methyl-7- (2,4-xylidino) fluorane, 3-diethylamino-6-methyl-7- (3,5-
Xylidino) fluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-di-n-propylamino-6-methyl-7-anilinofluorane, 3-
(N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-)
Cyclohexylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N- Ethyl-p-toluidino)-
6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3-di-n-butylamino-6-methyl-7. -Anilinofluorane, 3-di-n-pentylamino-6-methyl-7-anilinofluorane, 3-
(N-methyl-N-propylamino) -6-methyl-7
-Anilinofluorane, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-Nn-hexylamino) -6
-Methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-
Ethyl-N-isobutylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane,

3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino)
Fluorane, 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3- (N-ethyl-Nn)
-Hexylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-isopentylamino)
-7- (o-chloroanilino) fluorane, 3-di-n
-Butylamino-7- (o-fluoroanilino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-di-n-butylamino-6-methyl-7- (p-chloroanilino ) Fluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-di-n-butylamino-7- (p-trifluoromethylanilino) fluorane, 3-diethylamino-5-methyl- 7- (p-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-cyclopentylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-ethoxypropyl) amino -6-Methyl-7-anilinofluorane, 3- (N-methyl-N-ethoxypropyl) amino-6-methyl-7- Nirinofuruoran, 6-methyl-7-di -n- butylamino (m-toluidino) fluoran, di -n- butylamino-6-methyl-7- (3,
5-xylidino) fluorane and the like. Among them, 3-di-n-
Butylamino-6-methyl-7-anilinofluorane is particularly preferable because it is excellent in color development and background fog.

In the present invention, the phenothiazine derivative represented by the general formula (1) used in combination with the fluorane derivative as described above is a dye which produces a blue color tone when used alone, The following compounds and the like are exemplified. 3,7-bis (dimethylamino) -10
-Benzoylphenothiazine, 3,7-bis (diethylamino) -10-benzoylphenothiazine, 3,7-
Bis (di-n-butylamino) -10-benzoylphenothiazine, 3,7-bis (dimethylamino) -10-
(4-Methylbenzoyl) phenothiazine, 3,7-bis (diethylamino) -10- (4-methylbenzoyl) phenothiazine, 3,7-bis (di-n-butylamino) -10- (4-methylbenzoyl) phenothiazine 3,7-bis (dimethylamino) -10- (4-methoxybenzoyl) phenothiazine, 3,7-bis (dimethylamino) -10- (4-ethoxybenzoyl) phenothiazine, 3,7-bis (dimethylamino) -10
-(4-chlorobenzoyl) phenothiazine, 3,7-
Bis (dimethylamino) -10- (2-methylbenzoyl) phenothiazine, 3,7-bis (dimethylamino)
-10- (2-methoxybenzoyl) phenothiazine,
3,7-bis (dimethylamino) -10- (2-chlorobenzoyl) phenothiazine, 3,7-bis (di-n-
Butylamino) -10- (4-chlorobenzoyl) phenothiazine, 3-diethylamino-7-dimethylamino-10-benzoylphenothiazine and the like. Among these, the compounds represented by the following general formula (4) are particularly preferable because the raw materials are easily available, the cost is low, and the image storability, particularly, the light resistance is excellent. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

[0017]

Embedded image [In the general formula (4), R ₅ represents a hydrogen atom, a halogen atom, a C _{1 to} C ₄ alkyl group or a C _{1 to} C ₄ alkoxyl group. ]

In the heat-sensitive recording material of the present invention, the specific fluoran derivative and the specific phenothiazine derivative are used in combination at a specific ratio as described above. N represented by (3)
By selectively combining the -arylsulfonylurea compound, the OCR readability of a recorded image is excellently exhibited. Specific examples of the N-arylsulfonylurea compound include the following.

Bis (p-toluenesulfonylaminocarbonylamino) ketone, 1,2-bis (p-toluenesulfonylaminocarbonylamino) ethane, 1,1,
6,6-Tetra (p-toluenesulfonylaminocarbonylamino) hexane, 1,5-bis (p-toluenesulfonylaminocarbonylamino) -3-oxapentane, 1,5-bis (p-toluenesulfonylaminocarbonylamino) -3-Thiopentane, 1,3-bis (p
-Toluenesulfonylaminocarbonylamino) -2-
Propanone, tris [2- (p-toluenesulfonylaminocarbonylamino) ethyl] amine, 1,3-bis (p-toluenesulfonylaminocarbonylamino) benzene, 1,4-bis (p-toluenesulfonylaminocarbonylamino) benzene 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, 4,4'-bis (o-toluenesulfonylaminocarbonylamino) diphenylmethane, 4,4'-bis (benzenesulfonylaminocarbonylamino) diphenylmethane, 2,2-bis [4,4 '-(p-toluenesulfonylaminocarbonylamino) phenyl] propane, 1,2-bis [4- (p-toluenesulfonylaminocarbonylamino) phenyloxy] ethane, 2,
5-bis (p-toluenesulfonylaminocarbonylaminomethyl) furan, 1,3-bis (p-toluenesulfonylaminocarbonylaminomethyl) benzene,

1,4-bis (p-toluenesulfonylaminocarbonylaminomethyl) benzene, 1,5-bis (p-toluenesulfonylaminocarbonylaminomethyl) naphthalene, 1,8-bis (p-toluenesulfonylaminocarbonylamino) Methyl) naphthalene, 4,
4'-bis (p-toluenesulfonylaminocarbonylamino) diphenyl ether, 3,3'-bis (p-toluenesulfonylaminocarbonylamino) diphenylsulfone, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylsulfone , 4, 4 '
-Bis (p-ethylphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4 '-(p-methoxyphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4'-(o-methoxyphenylsulfonylaminocarbonylamino) diphenylmethane, 4,
4 '-(p-ethoxyphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4'-(p-isopropyloxyphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4 '-(p-benzyloxyphenylsulfonylaminocarbonylamino) diphenylmethane , 4,4 '-(p-chlorophenylsulfonylaminocarbonylamino) diphenylmethane, 4,
4 '-(2,4-dimethylphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4'-(2
3,4,5,6-pentachlorophenylsulfonylcarbonylamino) diphenylmethane, N- (p-toluenesulfonyl) -N'-phenylurea, N- (p-toluenesulfonyl) -N '-(p-tolyl) urea, N-
(P-Toluenesulfonyl) -N '-(m-tolyl) urea, N- (p-toluenesulfonyl) -N'-(o-
Trilyl) urea, N- (p-toluenesulfonyl)-
N '-(p-ethylphenyl) urea,

N- (p-toluenesulfonyl) -N'-
(Pn-propylphenyl) urea, N- (p-toluenesulfonyl) -N '-(pn-butylphenyl)
Urea, N- (p-toluenesulfonyl) -N '-(o
-Methoxyphenyl) urea, N- (p-toluenesulfonyl) -N '-(p-methoxyphenyl) urea, N
-(P-toluenesulfonyl) -N '-(o-ethoxyphenyl) urea, N- (p-toluenesulfonyl)-
N '-(p-ethoxyphenyl) urea, N- (p-toluenesulfonyl) -N'-(p-chlorophenyl) urea, N- (p-toluenesulfonyl) -N '-(o-
Chlorophenyl) urea, N- (p-toluenesulfonyl) -N '-(m-chlorophenyl) urea, N- (p
-Toluenesulfonyl) -N '-(2,4-dichlorophenyl) urea, N- (p-toluenesulfonyl)-
N '-(2,4,6-trimethylphenyl) urea, N
-(P-toluenesulfonyl) -N '-(2,3,4
5,6-pentachlorophenyl) urea,

N- (p-toluenesulfonyl) -N'-
(O-Hydroxyphenyl) urea, N- (p-toluenesulfonyl) -N '-(m-hydroxyphenyl) urea, N- (p-toluenesulfonyl) -N'-(p-
Hydroxyphenyl) urea, N-benzenesulfonyl-N'-phenylurea, N-benzenesulfonyl-
N '-(p-tolyl) urea, N-benzenesulfonyl-N'-(p-methoxyphenyl) urea, N-benzenesulfonyl-N '-(p-chlorophenyl) urea,
N-benzenesulfonyl-N '-(p-hydroxyphenyl) urea, N-benzenesulfonyl-N'-(o-
Hydroxyphenyl) urea, N-benzenesulfonyl-N '-(m-hydroxyphenyl) urea, N- (p
-Chlorophenylsulfonyl) -N'-phenylurea, N- (o-toluenesulfonyl) -N'-phenylurea, N- (p-ethylphenylsulfonyl) -N '
-Phenylurea, N- (p-methoxyphenylsulfonyl) -N'-phenylurea, N- (o-methoxyphenylsulfonyl) -N'-phenylurea, N- (p
-Ethoxyphenylsulfonyl) -N'-phenylurea, N- (p-isopropoxyphenylsulfonyl)-
N'-phenylurea, N- (p-benzyloxyphenylsulfonyl) -N'-phenylurea, N- (2,
4-dimethylphenylsulfonyl) -N'-phenylurea, N- (2,3,4,5,6-pentachlorophenylsulfonyl) -N'-phenylurea and the like. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Among these N-arylsulfonylurea derivatives, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane and N-
(P-toluenesulfonyl) -N'-phenylurea,
N- (p-toluenesulfonyl) -N '-(p-hydroxyphenyl) urea is more preferable because it gives a thermal recording material having excellent recording sensitivity and OCR readability under high temperature and high humidity, as well as background fog. Used.
In the present invention, the specific N-arylsulfonylurea compound as described above is selectively used as a color-developing agent, but other known color-developing agents within a range that does not inhibit the desired effects of the present invention. It is also possible to use together.

The thermal recording material of the present invention generally comprises a fluoran derivative and a phenothiazine derivative represented by the above general formula (1) in a medium in which a binder is dissolved or dispersed.
Further, it is produced by coating a suitable support with a coating liquid obtained by dispersing fine particles of the N-arylsulfonylurea derivative represented by the general formula (2) or (3) as a coloring agent.

The use ratio of the basic dye and the color former in the recording layer is not particularly limited, but generally 100 to 1000 parts by weight, preferably 200 to 100 parts by weight of the dye.
500 parts by weight of color former are used. The coating liquid containing them is generally prepared by dispersing the dye and the color former together or separately by using water as a dispersion medium and a stirring / pulverizing machine such as a ball mill, an attritor or a sand mill. Of course, the fluoran derivative and the phenothiazine derivative represented by the general formula (Formula 1) can also be dispersed together or separately.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer are usually used as binders. Combined salt, styrene-butadiene copolymer emulsion, etc. are 10 to 40% by weight of the total solid content, preferably 15 to 3%.
About 5% by weight is used.

Further, various auxiliaries can be added to the coating liquid, for example, dispersion of sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, fatty acid metal salt and the like. Agent, UV absorbers such as triazoles,
Other examples include defoaming agents, fluorescent dyes, coloring dyes and antioxidants. Also, in order to prevent sticking of the thermal recording material due to contact with recording equipment or recording heads, use a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. in the paint. It can also be added.

Further, in the heat-sensitive recording material of the present invention,
The recording layer may contain the following compounds as a recording sensitivity improving agent. Caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide,
Oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, N-methylstearic acid amide, stearic acid anilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyl Lauric acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleylbenzamide, N-stearylcyclohexylamide, polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene,
1-Hydroxynaphthoic acid phenyl ester, 1,2-
Diphenoxyethane, 1,4-diphenoxybutane,
1,2-bis (3-methylphenoxy) ethane, 1,2
-Bis (4-methoxyphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane, 1-
(2-Methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, p-benzyloxybenzoic acid benzyl ester, p -Benzylbiphenyl, 1,5-bis (p
-Methoxyphenoxy) -3-oxa-pentane, 1,
4-bis (2-vinyloxyethoxy) benzene, p-
Biphenyl-p-tolyl ether, benzyl-p-methylthiophenyl ether, 2- (2'-hydroxy-
5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone and the like.

The amount of the recording sensitivity improver used is not particularly limited, but is generally 50 to 1000 parts by weight, preferably 10 parts by weight with respect to 100 parts by weight of the basic dye.
It is preferably used in the range of 0 to 500 parts by weight. In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay can be added in order to improve adhesion of dust to the recording head.

The support may be paper, plastic film, synthetic paper, or a plastic film or synthetic paper laminated with coated paper or high-quality paper via an adhesive, or a paper laminated with plastic. used. Examples of such plastic film include films of polyethylene, polyester, polypropylene, polyvinyl chloride, polystyrene, nylon and the like. As the synthetic paper, for example, synthetic paper manufactured by the film method or the fiber method is used.
The film method includes an internal paper making method in which a synthetic resin, a filler, and an additive are melt-kneaded and then extruded to form a film, a surface coating method in which a pigment coating layer is provided, a surface treatment method, and the like. Include synthetic pulp paper and spunbond paper.

The method of applying the recording layer is not particularly limited, and it can be formed according to a conventionally well-known and commonly used technique, for example, bar coating, air knife coating, rod blade coating, pure blade coating, short dwell coating. And the like. When a plastic film is used as the support, the coating efficiency can be increased by subjecting the surface to treatments such as corona discharge and electron beam irradiation. The coating amount of the coating liquid is also not particularly limited, but it is usually ^{2 to} 10 g / m ² , preferably 3 to 7 g in dry weight.
It is adjusted in the range of about / m ² .

Further, by providing a protective layer composed of an adhesive, a lubricant, a pigment and the like on the thermosensitive recording layer, a thermosensitive recording material excellent in printability, redness and writing characteristics can be obtained. Specific examples of the adhesive used for the protective layer include, for example, polyvinyl alcohols with various degrees of saponification, acetoacetyl group-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol,
Acrylic resins and polyurethane resins are mentioned. Further, it is desirable that these adhesives are adjusted in the range of 10 to 95% by weight, preferably 30 to 90% by weight, based on the total solid content. The coating amount of the protective layer is 0.1 in dry weight.
It is adjusted in the range of 5 to 10 g / m ² , preferably about 1 to 7 g / m ² .

In addition, it is possible to provide a layer containing a water-soluble, water-dispersible, electron beam curable or ultraviolet curable resin on the protective layer for the purpose of imparting high gloss and the like. It is of course possible to provide a protective layer on the back surface of the recording medium or to provide an undercoat layer on the support, and various known techniques in the field of producing a thermosensitive recording medium can be added.

[0034]

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, parts and% in the examples represent parts by weight and% by weight, respectively.

Example 1 [Preparation of solution A] 3-di-n-butylamino-6-methyl-
7-anilinofluorane 10 parts, 5 of methylcellulose
% Aqueous solution 3 parts and water 27 parts were pulverized with a sand mill until the average particle size was 0.8 μm, to obtain a liquid A.

[Preparation of solution B] A composition comprising 10 parts of 3,7-bis (dimethylamino) -10-benzoylphenothiazine, 3 parts of a 5% aqueous solution of methylcellulose, and 27 parts of water was sand milled to give an average particle diameter of 0.8 μm. It was pulverized until it became, and a liquid B was obtained.

[Preparation of Solution C] A composition comprising 20 parts of 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was sand milled to give an average particle size of 1 ．
It was pulverized to a size of 2 μm to obtain a liquid C.

[Preparation of Solution D] A composition comprising 25 parts of 1,2-bis (3-methylphenoxy) ethane, 7 parts of a 5% aqueous solution of methylcellulose, and 48 parts of water was sand-milled to an average particle size of 1.2 μm. Was pulverized to obtain a liquid D.

[Formation of Recording Layer] Liquid A 32 parts, liquid B 8 parts,
Liquid C 80 parts, liquid D 80 parts, light calcium carbonate 10 parts,
50 g / m ^{2 of} a coating liquid obtained by mixing and stirring 20 parts of fine particle silicon oxide pigment (oil absorption 180 ml / 100 g), 15 parts of a 30% dispersion of zinc stearate, and 100 parts of a 15% aqueous solution of polyvinyl alcohol. 4g dry weight on high quality paper
It was coated and dried so as to be / m ^2, and subjected to a super calender treatment to obtain a heat-sensitive recording material.

Examples 2-5 In the preparation of solution B, 3,7-bis (dimethylamino)-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the following compound was used instead of 10-benzoylphenothiazine. Example 2: 3,7-bis (dimethylamino) -10-
(4-Methylbenzoyl) phenothiazine Example 3: 3,7-Bis (dimethylamino) -10-
(4-Methoxybenzoyl) phenothiazine Example 4: 3,7-Bis (diethylamino) -10-
Benzoylphenothiazine Example 5: 3,7-Bis (di-n-butylamino)-
10- (4-chlorobenzoyl) phenothiazine

Examples 6 to 7 Thermal recording was carried out in the same manner as in Example 1 except that the following compound was used in place of 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane in the preparation of the C liquid. Got the body Example 6: N- (p-toluenesulfonyl) -N'-
Phenylurea Example 7: N- (p-toluenesulfonyl) -N'-
(P-hydroxyphenyl) urea

Example 8 In preparation of solution A, 3-di-n-butylamino-6-methyl-7-anilinofluorane was replaced with 3-diethylamino-7- (m-trifluoromethylanilino) fluorane. A thermal recording material was obtained in the same manner as in Example 1 except that the thermal recording material was used.

Examples 9 to 12 Thermal recording was carried out in the same manner as in Example 1 except that in the formation of the recording layer, A solution and B solution were used in the following ratios instead of 32 parts of A solution and 8 parts of B solution. Got the body Example 9: A solution 24 parts, B solution 16 parts Example 10: A solution 28 parts, B solution 12 parts Example 11: A solution 36 parts, B solution 4 parts Example 12: A solution 38 parts, B solution 2 copies

Comparative Examples 1 to 3 Thermal recording was carried out in the same manner as in Example 1 except that in the formation of the recording layer, A solution and B solution were used in the following ratios instead of 32 parts A solution and 8 parts B solution. Got the body Comparative Example 1: Liquid A 40 parts, Liquid B 0 part Comparative Example 2: Liquid A 39 parts, Liquid B 1 part Comparative Example 3: Liquid A 16 parts, Liquid B 24 parts

Comparative Examples 4 to 5 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following compounds were used in place of 3,7-bis (dimethylaminophenyl) -10-benzoylphenothiazine in the preparation of solution B. Got Comparative Example 4: 3,3-bis (4-diethylamino-2-)
Ethoxyphenyl) -4-azaphthalide Comparative Example 5: 3-di-n-butylamino-6,8,8-
Trimethyl-8,9-dihydro- (3,2, e) pyridfluorane

Comparative Example 6 The same as Example 1 except that 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane was replaced with 4,4'-isopropylidenediphenol in the preparation of the liquid C. A thermosensitive recording medium was obtained.

The heat-sensitive recording material thus obtained was evaluated by the following methods, and the results are shown in Table 1. [PCS value] The PCS value is an index indicating the degree of readability of OCR. The PCS value represents the relative density difference between the recorded portion and the unrecorded portion, and is calculated by the following equation. PCS = (RW-RP) / RW RW represents the reflectance of the unrecorded portion, and RP represents the reflectance of the recorded portion. Therefore, the higher the PCS value, the clearer the discrimination between the recorded portion and the unrecorded portion, and the higher the readability.
Generally, a PCS value of 0.7 or more, preferably 0.8 or more is required.

[Measurement of PCS value at 670 nm] Recording was performed using a thermal recording evaluation device [TM-PMD type, manufactured by Okura Electric Co., Ltd., applied voltage 16V, pulse cycle 0.51 ms, applied pulse width 0.3 ms]. The reflectance of the unrecorded area at a wavelength of 670 nm was measured with a spectrophotometer [U-3300, manufactured by Hitachi, Ltd.], and the PCS value was calculated from the value. The color tones of the obtained recorded images were all black.

[Background Fogging] The unrecorded area was measured with a Macbeth densitometer [Macbeth RD-914 model, visual filter].

[Moisture and heat resistance] After recording, 50 ° C., 90% RH
After being left for 72 hours under the above condition, the PCS value and the background fog were measured.

[Light resistance] After recording, after exposure to direct sunlight for 24 hours, the PCS value and the background fog were measured.

[Plasticizer resistance] After recording, a vinyl chloride film was overlaid on the coloring surface and left at room temperature for 8 hours, and then the PCS value and the background fog were measured.

[0053]

[Table 1]

[0054]

As is clear from the results of [Table 1], the thermosensitive recording medium of the present invention has a PCS value at 670 nm even when stored under high temperature and high humidity, exposed to light for a long time, or exposed to a chemical. Was sufficiently high and there was little background fog.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Tsuchida 4-3-1, Jokoji Temple, Amagasaki City, Hyogo Prefecture Shin-Oji Paper Co., Ltd. Kanzaki Mill

Claims (3)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein at least a black coloring fluoran derivative is used as the basic dye in the recording layer. One and at least one phenothiazine derivative represented by the following general formula (1) are contained so that the phenothiazine derivative is 5 to 100% by weight of the fluoran derivative, and the following general formula (2) is used as a coloring agent. Alternatively, a heat-sensitive recording material containing an N-arylsulfonylurea compound represented by (3). [Chemical 1] [In the general formula (1), R _{1 to} R ₄ are each C ₁ to
A C ₄ alkyl group is shown, and R ₅ is a hydrogen atom, a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxyl group. ] [Chemical 2] [In the general formula (2), R ₆ is a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group, a benzyloxy group,
A halogen atom or a hydroxyl group is shown, A is a divalent, trivalent or tetravalent group, n is an integer of 2 to 4 and m is an integer of 0 to 5. ] [Chemical 3] [In the general formula (3), R ₇ and R ₈ are each C ₁ to
C ₄ alkyl group, C ₁ -C ₄ alkoxyl group, benzyloxy group, halogen atom or hydroxyl group, p,
q shows the integer of 0-5, respectively. ] 2. A phenothiazine derivative represented by the following general formula (4):
The heat-sensitive recording material according to claim 1, which is a compound represented by: [Chemical 4] [In the general formula (4), R ₅ represents a hydrogen atom, a halogen atom, a C _{1 to} C ₄ alkyl group or a C _{1 to} C ₄ alkoxyl group. ] 3. The N-arylsulfonylurea compound is 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, N- (p-toluenesulfonyl) -N'-phenylurea or N- (p-toluenesulfonyl). ) -N '-(p-hydroxyphenyl) urea.