JP2003063144A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording material, which has high color developing density, minor ground fogging, is excellent in the preservability of an image part and in the resistance to chemicals of the image part and of a ground part and, at the same time, is equipped with ink jet recordability. SOLUTION: In the heat sensitive recording material having a heat sensitive color developing layer including an electron donable colorless dye, and an electron acceptive compound on a support, the heat sensitive color developing layer includes at least one kind selected from the group consisting of 2-anilino-3- methyl-6-di-n-butyl aminofluoran and 2-anilino-3-methyl-6-di-n-amyl aminofluoran as the electron donative colorless dye and 4-hydroxybenzene sulfonanilide as the electron acceptive compound.

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 having high sensitivity, low background fog, excellent image storability and chemical resistance, and ink jet recording suitability.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is relatively inexpensive, and its recording equipment is compact and maintenance-free, and thus is widely used. Under such circumstances, recently, the sales competition of thermal paper has intensified, and it has been required to further enhance the functionality of the thermal recording material that is differentiated from the conventional functions, and research on the color density and image storability of the thermal recording material. Is earnestly done.

Conventionally, 2,2-bis (4-hydroxyphenyl) propane (so-called "bisphenol A") has been widely used as an electron-accepting compound for an electron-donating colorless dye used in such a heat-sensitive recording material. However, satisfactory results have not been obtained in terms of sensitivity, background fog, and image storability. On the other hand, Japanese Patent Publication No. 4-20792
The publication describes a recording material using N-substituted sulfamoylphenol or N-substituted sulfamoylnaphthol as an electron-accepting compound.
Heat sensitivity) is described to improve image density, image stability, cost, etc., but there is room for further improvement in image density, image storability, etc.

When full-color information is recorded on a heat-sensitive recording material, ink-jet ink may be used for recording. When ink-jet recording is performed on a normal heat-sensitive recording material, the ink color is reproduced faithfully. The color may not be vivid and may be dull. Further, it has been found that there is a problem in that the color is dull and blackish when ink jet recording is performed on the thermosensitive recording material described in Japanese Patent Publication No. 4-20792.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above problems and has a high coloring density,
An object of the present invention is to provide a heat-sensitive recording material having less background fog, excellent storability in the image area, excellent chemical resistance in the image area and the background area, and suitable for inkjet recording.

[0006]

The above-mentioned problems can be solved by providing the following heat-sensitive recording material. <1> A heat-sensitive recording material having a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound on a support, wherein the thermosensitive coloring layer is 2-anilino-as an electron-donating colorless dye. 3-Methyl-6-di-n-butylaminofluorane and 2-anilino-3-methyl-6-di-n
A heat-sensitive recording material containing at least one selected from amylaminofluorane and 4-hydroxybenzenesulfonanilide as an electron-accepting compound.

<2> The heat-sensitive recording material according to <1>, wherein the electron-accepting compound is contained in an amount of 100 to 300 parts by mass based on 100 parts by mass of the electron-donating colorless dye. <3> The thermosensitive coloring layer contains a sensitizer, and the sensitizer contains 2-
<1> or <2>, which is at least one selected from benzylnaphthyl ether (2-benzyloxynaphthalene), 1,2-bis (3-methylphenoxy) ethane, and 1,2-diphenoxymethylbenzene. It is a thermosensitive recording material. <4> The heat-sensitive recording material according to <3>, wherein the sensitizer is contained in 100 to 300 parts by mass with respect to 100 parts by mass of the electron-donating colorless dye.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording material of the present invention has, on a support, a heat-sensitive color forming layer containing an electron-donating colorless dye and an electron-accepting compound, and the heat-sensitive color forming layer has an electron-donating property. 2-anilino-3-methyl-6-di-n as colorless dye
-Butylaminofluorane and at least one selected from 2-anilino-3-methyl-6-di-n-amylaminofluorane and 4-hydroxybenzenesulfonanilide as an electron-accepting compound.

The heat-sensitive recording material of the present invention comprises 2-anilino-3-methyl-6-di-n-butylaminofluorane and 2-anilino-3-methyl- as colorless electron-donating dyes.
Since at least one selected from 6-di-n-amylaminofluorane is used and 4-hydroxybenzenesulfonanilide is used as the electron accepting compound,
It has high sensitivity, little background fog, excellent image storability and chemical resistance, and excellent inkjet recording suitability.
The thermal recording material of the present invention will be described in detail below.

<Thermosensitive Coloring Layer> As described above, the thermosensitive coloring layer contains at least an electron-donating colorless dye and an electron-accepting compound, and if necessary, a sensitizer, an image stabilizer and an ultraviolet absorber. Agents and the like may be contained.

(Electron-donating colorless dye) The heat-sensitive recording material of the present invention contains 2-anilino-3 as an electron-donating colorless dye.
-Methyl-6-di-n-butylaminofluorane and 2
-Anilino-3-methyl-6-di-n-amylaminofluorane is contained.

As the electron-donating colorless dye, the above-mentioned 2
-Anilino-3-methyl-6-di-n-butylaminofluorane and 2-anilino-3-methyl-6-di-n-
Other than amylaminofluorane, other electron-donating colorless dyes may be used in combination as long as the effects of the present invention are not impaired. When another electron-donating colorless dye is used in combination, the above-mentioned 2-
The content of anilino-3-methyl-6-di-n-butylaminofluorane and 2-anilino-3-methyl-6-di-n-amylaminofluorane (when used in combination, the total content of both) is It is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% or more of the total electron donating colorless dye.

Other electron-donating colorless dyes include, for example, 2-anilino-3-methyl-6- (N-ethyl-N).
-P-benzyl) aminofluorane, 2-anilino-3
-Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (N-ethyl-N-isoamylamino) fluorane, 2-anilino-3-methyl-6-
(N-ethyl-N-propylamino) fluorane, 2-
Anilino-3-methyl-6-N-ethyl-N-sec-
Butylaminofluorane, 3- (N-isoamyl-N-
Ethylamino) -6-methyl-7-anilinofluorane, 3- (Nn-hexyl-N-ethylamino) -6
-Methyl-7-anilinofluorane, 3- [N- (3-
Ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluorane, 3-di (n-butylamino) -7- (2-chloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) ) Fluoran, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane and the like.

[0014] Examples of the coating amount of the electron-donating colorless dye, 0.1 to 1.0 g / m ² are preferred, color density and 0.2~0.5g terms of background fog density / m ² Gayori preferable.

(Electron-Accepting Compound) The heat-sensitive recording material of the present invention is characterized by containing 4-hydroxybenzenesulfonanilide as an electron-accepting compound. The content of the electron-accepting compound is preferably 100 to 300 parts by mass, more preferably 150 to 300 parts by mass, and more preferably 200 to 250 parts by mass with respect to 100 parts by mass of the electron-donating colorless dye. Is more preferable. When the content of the electron accepting compound is within the above range, the effects of the present invention can be more effectively exhibited.

As the electron-accepting compound, besides 4-hydroxybenzenesulfonanilide, other electron-accepting compound may be used in combination as long as the effect of the present invention is not impaired. When used in combination with another electron-accepting compound,
The content of the 4-hydroxybenzenesulfonanilide is preferably 50% by mass or more, more preferably 70% by mass or more, of the total electron-accepting compound.
It is more preferably 90% by mass or more.

Other electron-accepting compounds can be appropriately selected and used, but a phenolic compound, a salicylic acid derivative and a polyvalent metal salt thereof are particularly preferable from the viewpoint of suppressing background fogging. Examples of the phenolic compound include 2,2'-bis (4-hydroxyphenol) propane (bisphenol A), 4-t-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, 1,1'-bis. (4-hydroxyphenyl) cyclohexane, 1,1′-bis (3-chloro-4-hydroxyphenyl) cyclohexane, 1,
1'-bis (3-chloro-4-hydroxyphenyl)-
2-ethylbutane, 4,4'-sec-isooctylidenediphenol, 4,4'-sec-butylylenediphenol, 4-tert-octylphenol, 4-p-
Methylphenylphenol, 4,4'-methylcyclohexylidenephenol, 4,4'-isopentylidenephenol, 4-hydroxy-4-isopropyloxydiphenylsulfone, benzyl p-hydroxybenzoate and the like can be mentioned.

As the salicylic acid derivative, 4
-Pentadecylsalicylic acid, 3-5-di (α-methylbenzyl) salicylic acid, 3,5-di (tert-octyl) salicylic acid, 5-octadecylsalicylic acid, 5-α
-(P-α-methylbenzylphenyl) ethylsalicylic acid, 3-α-methylbenzyl-5-tert-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4
-Octadecyloxysalicylic acid and the like and zinc thereof,
Aluminum, calcium, copper, lead salts and the like are also included.

In preparing the coating liquid for the thermosensitive color developing layer in the present invention, the particle diameter of the electron-accepting compound is preferably 1.0 μm or less in terms of volume average particle diameter, and 0.4 to
It is more preferably 0.7 μm. If the volume average particle size exceeds 1.0 μm, the thermal sensitivity may be reduced. The volume average particle size can be easily measured by a laser diffraction particle size distribution measuring device (for example, LA500 (manufactured by Horiba Ltd.) or the like.

(Sensitizer) In the heat-sensitive recording material of the present invention, 2-benzylnaphthyl ether, 1,2-bis (3-methylphenoxy) is used as a sensitizer in the heat-sensitive color forming layer.
It is preferable to contain at least one selected from ethane and 1,2-diphenoxymethylbenzene. By containing these sensitizers, the sensitivity can be further improved.

The content of the sensitizer is preferably 100 to 300 parts by mass, more preferably 150 to 300 parts by mass, and more preferably 200 to 250 parts by mass with respect to 100 parts by mass of the electron-donating colorless dye. More preferably, it is a part. When the content of the sensitizer is within the above range, the effect of improving the sensitivity is great and the image storability is also improved.

As the sensitizer, other than the above-mentioned 2-benzylnaphthyl ether, 1,2-bis (3-methylphenoxy) ethane and 1,2-diphenoxymethylbenzene, the effect of the present invention is not impaired. Within the range, other sensitizers may be used in combination. When using together with other sensitizers,
The 2-benzylnaphthyl ether, 1,2-bis (3
The content of (methylphenoxy) ethane and 1,2-diphenoxymethylbenzene (the total content when these are used in combination) is preferably 50% by mass or more, and 70% by mass or more based on the total sensitizer. Is more preferable, and 9
It is more preferably 0% by mass or more.

Other sensitizers include dimethylbenzyl oxalate, m-terphenyl, ethylene glycol tolyl ether, p-benzyl biphenyl, aliphatic monoamide, stearyl urea, di (2-methylphenoxy) ethane, di (2). -Methoxyphenoxy) ethane, β-naphthol- (p-methylbenzyl) ether, α-naphthylbenzyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-
Isopropyl phenyl ether, 1,4-butanediol-p-tert-octyl phenyl ether, 1-phenoxy-2- (4-ethylphenoxy) ethane, 1-
Phenoxy-2- (chlorophenoxy) ethane, 1,4
-Butanediol phenyl ether, diethylene glycol bis (4-methoxyphenyl) ether, oxalic acid methylbenzyl ether, 1,2-diphenoxymethylbenzene, 1,4-bis (phenoxymethyl) benzene and the like can be mentioned.

(Image Stabilizer / Ultraviolet Absorber) Further, the thermosensitive coloring layer may contain an image stabilizer and an ultraviolet absorber. As the image stabilizer, a phenol compound, particularly a hindered phenol compound is effective. For example, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3.
-Tris (2-ethyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (3,5
-Di-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) propane, 2,
2'-methylene-bis (6-tert-butyl-4-methylphenol), 2,2'-methylene-bis (6-t
ert-butyl-4-ethylphenol) 4,4′-butylidene-bis (6-tert-butyl-3-methylphenol), 4,4′-thio-bis- (3-methyl-6)
-Tert-butylphenol) and the like.

Examples of the ultraviolet absorber include the following ultraviolet absorbers and the like.

[0026]

[Chemical 1]

In the present invention, an electron donating colorless dye,
The electron-accepting compound and the sensitizer can be dispersed in a water-soluble binder. The water-soluble binder used in this case is preferably a compound that dissolves in 5% by mass or more of water at 25 ° C.

Specific examples of the above water-soluble binder include:
Polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene-
Examples thereof include saponified maleic anhydride copolymers.

These binders are not only used at the time of dispersion,
It is also used for the purpose of improving the coating strength of the thermosensitive coloring layer, but for this purpose, a styrene-butadiene copolymer, a vinyl acetate copolymer, an acrylonitrile-butadiene copolymer, a methyl acrylate-butadiene copolymer is used. Polymer,
A binder of a synthetic polymer latex such as polyvinylidene chloride may be used together.

The above-mentioned electron-donating colorless dye, electron-accepting compound, sensitizer and the like are simultaneously or separately dispersed by a stirrer / pulverizer such as a ball mill, attritor or sand mill to prepare a coating liquid. In the coating liquid, if necessary, various pigments, metal soaps, waxes, surfactants,
An antistatic agent, an antifoaming agent, a fluorescent dye, etc. may be added.

The above pigments include calcium carbonate, barium sulfate, lithopone, wax stone, kaolin, calcined kaolin,
Amorphous silica and aluminum hydroxide are used.
As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, and aluminum stearate.

As the above wax, paraffin wax, microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax and fatty acid amide wax may be used alone or in combination. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant or the like is used.

These materials are mixed and then applied to the support. The coating method is not particularly limited, and for example, it is coated with an air knife coater, roll coater, blade coater, curtain coater or the like, dried, and then smoothed with a calender to be used. In particular, a method using a curtain coater is preferable for the present invention. Further, the coating amount of the heat-sensitive color forming layer is not limited, and usually a dry mass of about ² to 7 g / m ² is preferable.

<Protective Layer> A protective layer may be provided on the thermosensitive coloring layer, if desired. The protective layer may contain organic or inorganic fine powder, a binder, a surfactant, a heat fusible substance and the like. As fine powder,
For example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
In addition to clay, talc, inorganic fine powder such as surface-treated calcium and silica, organic fine powder such as urea-formalin resin, styrene / methacrylic acid copolymer and polystyrene can be used.

As the binder in the protective layer, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, gelatins, arabic gum, casein. , Styrene-maleic acid copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, and styrene-
Latexes such as butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion can be used.

It is also possible to add a water resistant agent for further improving the storage stability of the heat-sensitive recording material by crosslinking the binder component in the protective layer. Water-resistant agents include water-soluble initial condensates such as N-methylol urea, N-methylol melamine and urea-formalin, dialdehyde compounds such as glyoxal and glutaraldehyde, and inorganic crosslinking agents such as boric acid, borax and colloidal silica. , Polyamide epichlorohydrin and the like.

<Support> As the support used in the present invention, a conventionally known support can be used. Specific examples thereof include a paper support such as high-quality paper, a coated paper obtained by coating paper with a resin or a pigment, a resin-laminated paper, a high-quality paper having an undercoat layer, a synthetic paper, or a plastic film.

When an undercoat layer is provided on the support, it is preferable to provide an undercoat layer containing a pigment as a main component. As the pigment, general inorganic and organic pigments can be used,
In particular, the oil absorption specified by JIS-K5101 is 40 ml /
It is preferably 100 g (cc / 100 g) or more. Specific examples thereof include calcium carbonate, barium sulfate, aluminum hydroxide, kaolin, calcined kaolin, amorphous silica, and urea formalin resin powder. Among these, calcined kaolin having an oil absorption of 70 ml / 100 g or more is particularly preferable. Further, the coating amount of the undercoat layer is 2 g / m ² or more, preferably 4 g / m ² or more, and 7 g / m ^{2 to} 12 g / m ² are particularly preferable in terms of weight after drying.

Examples of the binder used in the undercoat layer include water-soluble polymers and aqueous binders.
These may be used alone or in combination of two or more. Examples of the water-soluble polymer include starch, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, methyl cellulose, casein and the like. As the aqueous binder, synthetic rubber latex or synthetic resin emulsion is generally used, and examples thereof include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. The amount of these binders used is 3 to 100% by mass, preferably 5 to 50% by mass, and particularly preferably 8 to 15% by mass, based on the pigment added to the undercoat layer. Further, wax, a decoloring inhibitor, a surfactant and the like may be added to the undercoat layer.

A known coating method can be used to coat the undercoat layer. Specifically, a method using an air knife coater, a roll coater, a blade coater, a gravure coater, a curtain coater or the like can be used,
Of these, the method using a blade coater is preferable. Further, if necessary, a smoothing process such as a calendar may be applied before use.

[0041]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by mass" and "% by mass", respectively.

Example 1 <Formation of thermosensitive recording material><Preparation of coating liquid for thermosensitive coloring layer> (Preparation of dispersion A (electron donating colorless dye)) The following components were mixed while being dispersed by a ball mill. A dispersion A having an average particle diameter of 0.7 μm was obtained. [Dispersion A composition] 2-anilino-3-methyl-6-di-n-butylaminofluorane 10 parts Polyvinyl alcohol 2.5% solution (PVA-105, manufactured by Kuraray Co., Ltd.) 50 parts

(Preparation of dispersion B (electron-accepting compound))
The following components were dispersed in a ball mill and mixed to obtain a dispersion B having an average particle size of 0.7 μm. [Dispersion B composition] 4-hydroxybenzenesulfonanilide 20 parts Polyvinyl alcohol 2.5% solution (PVA-105, manufactured by Kuraray Co., Ltd.) 100 parts

(Preparation of Dispersion C (sensitizer)) The following components were mixed while being dispersed by a ball mill to obtain Dispersion C having an average particle size of 0.7 μm. [Dispersion C composition] 2-benzylnaphthyl ether (sensitizer) 20 parts Polyvinyl alcohol 2.5% solution (PVA-105, manufactured by Kuraray Co., Ltd.) 100 parts

(Preparation of Pigment Dispersion Liquid D) The following components were dispersed in a sand mill and mixed to obtain an average particle diameter of 2.0 μm.
A pigment dispersion D of m was obtained. [Pigment Dispersion D Composition] -Light calcium carbonate ... 40 parts-Sodium polyacrylate--1 part-Water--60 parts

A compound having the following composition was mixed to obtain a coating solution for a thermosensitive color developing layer. [Composition of coating liquid for thermosensitive color forming layer] Dispersion A ... 60 parts Dispersion B ... 120 parts Dispersion C ... 120 parts Pigment dispersion D ... 101 parts Zinc stearate 30% dispersion ... 15 parts Paraffin wax (30%) 15 parts Sodium dodecylbenzene sulfonate (25%) 4 parts

<Preparation of Coating Liquid for Undercoat Layer of Support> The following components were stirred and mixed with a dissolver to obtain a dispersion liquid. -Calcined kaolin (oil absorption 75 ml / 100 g) ... 100 parts-Sodium hexametaphosphate ... 1 part-Water ... 110 parts SBR (styrene-butadiene rubber latex) 20 parts and oxidized starch (25%) 25 in the obtained dispersion liquid. Parts to obtain a coating solution for the undercoat layer of the support.

<Preparation of Coating Liquid for Protective Layer> First, the following composition was dispersed by a sand mill to prepare a pigment dispersion having an average particle diameter of 2 μm. Aluminum hydroxide (average particle diameter 1 μm) 40 parts (Hidilite H42, Showa Denko KK) Sodium polyacrylate 1 part Water 60 parts Separately, urea phosphate esterified starch 15% aqueous solution ( M
S4600, manufactured by Nippon Shokuhin Kako Co., Ltd., 200 parts and polyvinyl alcohol 15% aqueous solution (PVA-105,
(Kuraray Co., Ltd.) 200 parts of water and 60 parts of water were prepared, and the pigment dispersion was mixed therewith, and further zinc stearate emulsion dispersion (Hydrin F115, Chukyo Yushi Co., Ltd.) having an average particle diameter of 0.15 μm was prepared. (Manufactured by KK) and 25 parts of sulfosuccinic acid 2-ethylhexyl ester sodium salt 2% aqueous solution were mixed to obtain a coating liquid for protective layer.

<Preparation of Thermosensitive Recording Material> Weighing 50 g / m ²
On a high-quality base paper, a coating solution for the undercoat layer of the support was applied by a blade coater so that the applied amount after drying was 8 g / m ^2, and after the layer was dried, a calendering treatment was applied to give an undercoated paper. It was made. Then, the coating solution for heat-sensitive recording material was coated on the undercoat layer by a curtain coater so that the coating amount after drying was 4 g / m ^2, and the coating solution for protective layer was further dried on the heat-sensitive color forming layer. Curtain coating so that the coating amount of 2 g / m ²
It was then dried. The surface of the formed protective layer was subjected to a calendering treatment to obtain the heat-sensitive recording material of Example 1.

Example 2 2-anilino-3-with the composition of dispersion A in Example 1
Methyl-6-di-n-butylaminofluorane was added to 2-
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that anilino-3-methyl-6-di-n-amylaminofluorane was used.

Example 3 20 parts of 4-hydroxybenzenesulfonanilide having the composition of the dispersion B in Example 1 was changed to 5 parts, and dispersion B having the composition of the coating solution for the thermosensitive color developing layer was changed from 120 parts to 105 parts. A thermosensitive recording material was prepared in the same manner as in Example 1 except that the changes were made. Example 4 20 parts of 4-hydroxybenzenesulfonanilide having the composition of dispersion B in Example 1 was changed to 10 parts, and dispersion B having the composition of the coating solution for the thermosensitive color developing layer was changed from 120 parts to 110 parts. A thermal recording material was prepared in the same manner as in Example 1.

Example 5 20 parts of 4-hydroxybenzenesulfonanilide of the composition of the dispersion B in Example 1 was changed to 30 parts, and dispersion B of the composition of the coating solution for the thermosensitive color developing layer was changed from 120 parts to 130 parts. A thermosensitive recording material was prepared in the same manner as in Example 1 except that the changes were made.

Example 6 The 2-benzylnaphthyl ether having the composition of the dispersion C in Example 1 was mixed with 1,2-bis (3-methylphenoxy).
A thermal recording material was prepared in the same manner as in Example 1 except that ethane was used.

Example 7 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the 2-benzylnaphthyl ether in the composition of the dispersion C in Example 1 was changed to 1,2-diphenoxymethylbenzene. .

Example 8 A thermosensitive recording material was prepared in the same manner as in Example 1 except that 2-benzylnaphthyl ether in the composition of the dispersion liquid C in Example 1 was changed to methylol stearamide.

Example 9 20 parts of 2-benzylnaphthyl ether having the composition of dispersion C in Example 1 was changed to 10 parts, and dispersion C of the coating liquid composition for the thermosensitive color developing layer was changed from 120 parts to 110 parts. A thermal recording material was produced in the same manner as in Example 1 except for the above. Example 10 20 parts of 2-benzylnaphthyl ether of the composition of the dispersion C in Example 1 was changed to 30 parts, and the dispersion C of the coating liquid composition for the thermosensitive color developing layer was changed from 120 parts to 130 parts, A thermal recording material was prepared in the same manner as in Example 1.

Comparative Example 1 A thermosensitive recording material was prepared in the same manner as in Example 1 except that bisphenol A was used instead of 4-hydroxybenzenesulfonanilide in the composition of the dispersion liquid B in Example 1.

Comparative Example 2 A thermosensitive recording material was prepared in the same manner as in Example 1 except that N-benzyl-4-hydroxybenzenesulfonamide was used instead of 4-hydroxybenzenesulfonanilide in the composition of the dispersion liquid B in Example 1. Was produced.

Comparative Example 3 2-anilino-3-with the composition of dispersion A in Example 1
Methyl-6-di-n-butylaminofluorane was added to 2-
Anilino-3-methyl-6- (N-cyclohexyl-N
-Methyl) aminofluorane, except for Example 1
A thermal recording material was prepared in the same manner as in.

Comparative Example 4 2-anilino-3-with the composition of dispersion A in Example 1
Methyl-6-di-n-butylaminofluorane, 3-
Dimethylamino-6-methyl-7- (m-toluidino)
-A thermosensitive recording material was prepared in the same manner as in Example 1 except that fluoran was used.

<< Evaluation of Thermosensitive Recording Material >> The following items were evaluated for Examples 1 to 10 and Comparative Examples 1 to 4. (1) Sensitivity For each thermal recording material, a thermal head (K
Printing was performed using a thermal printer having JT-216-8MPD1). The printing was performed with a head voltage of 24 V and a pulse period of 10 ms and a pulse width of 1.5 ms, and the printing density was measured with a Macbeth reflection densitometer (RD-918).

(2) Background fogging Each of the heat-sensitive recording materials was subjected to 2 in an environment of 60 ° C. and 20% relative humidity.
After standing for 4 hours, the background of each heat-sensitive recording material was measured with a Macbeth reflection densitometer (RD-918). The lower the value, the better the result.

(3) Image storability An image was recorded on each thermosensitive recording material under the same apparatus and conditions as in (1) above, and the image density immediately after printing was measured with a Macbeth reflection densitometer (RD-918). . Then 60
After being left for 24 hours in an atmosphere of 20 ° C. and 20% relative humidity, the image density after standing was measured by a Macbeth reflection densitometer (RD-918). The ratio of the image density after standing to the image density immediately after printing (image preservation rate) was calculated. The higher the value, the better the image storability. Image preservation ratio = [(image density after leaving under the above conditions) / (image density immediately after printing)] × 100

(4) Chemical resistance Each heat-sensitive recording material was printed under the same conditions as in (1) above, and a fluorescent pen (Zebra highlighter 2-pink, manufactured by Zebra Corporation) was printed on the background and the surface of the printed part. Then, the occurrence of background fog and the stability of the image area of each heat-sensitive recording material after 1 day were visually observed and evaluated according to the following criteria. [Criteria] ◯: No fogging was observed, and no change was observed in the image area. Δ: Some fogging was observed, and the image area became slightly thin. X: Fogging was remarkably observed, and the image area almost disappeared.

(5) Evaluation of suitability for ink jet printing On each heat sensitive recording material, an ink jet printer (MJ930 manufactured by Seiko Epson Corp.) was used to print red characters in super fine mode, and the color (fog) of the characters was changed. evaluated. [Criteria] O: Vivid red. Δ: Dull red. X: A color closer to black than red. The above results are shown in Table 1.

[0066]

[Table 1]

As is clear from Table 1, the heat-sensitive recording materials obtained in Examples 1 to 10 of the present invention had sensitivity, background fog, storage stability of color image, chemical resistance and ink jet recording suitability (fog). It turns out that it is excellent in both cases. On the other hand, in Comparative Example 1 using bisphenol A as the electron-accepting compound, the sensitivity, the image storability, the chemical resistance and the ink jet fog were not sufficient, and the electron-accepting compound was N-benzyl-4.
Comparative example 2 using -hydroxybenzenesulfonamide
However, in terms of sensitivity, image storability and ink jet fog, it was not sufficient. Further, Comparative Example 3 using 2-anilino-3-methyl-6- (N-cyclohexyl-N-methyl) aminofluorane as the electron-donating colorless dye, and 3-dimethylamino-6 as the electron-donating colorless dye. Comparative Example 4 using -methyl-7- (m-toluidino) -fluorane was not sufficient in terms of sensitivity.

[0068]

INDUSTRIAL APPLICABILITY According to the present invention, a heat-sensitive recording material having a high color density, little background fog, excellent storage stability in image areas, excellent chemical resistance in image areas and background areas, and suitability for ink jet recording. Can be provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirofumi Mitsuo             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. F-term (reference) 2H026 AA07 BB15 BB25 DD02 DD17                       DD23 DD45 DD53

Claims (4)

[Claims] 1. A heat-sensitive recording material having a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound on a support, wherein the thermosensitive coloring layer serves as an electron-donating colorless dye. An electron accepting compound containing at least one selected from anilino-3-methyl-6-di-n-butylaminofluorane and 2-anilino-3-methyl-6-di-n-amylaminofluorane A heat-sensitive recording material containing 4-hydroxybenzenesulfonanilide as the compound. 2. The heat-sensitive recording material according to claim 1, wherein the electron-accepting compound is contained in an amount of 100 to 300 parts by mass based on 100 parts by mass of the electron-donating colorless dye. 3. The thermosensitive coloring layer contains a sensitizer, and the sensitizer is 2-benzylnaphthyl ether, 1,2-bis (3-
The heat-sensitive recording material according to claim 1, which is at least one selected from methylphenoxy) ethane and 1,2-diphenoxymethylbenzene. 4. The heat-sensitive recording material according to claim 3, wherein the sensitizer is contained in an amount of 100 to 300 parts by mass based on 100 parts by mass of the electron-donating colorless dye.