JP2000006528A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a black image having the good stability of coloring density, the preservative stability of chemical resistance or the like in an image part and nonimage part, and excellent due by making an electron acceptable compound an anthranilic acid derivative expressed by a specific formula. SOLUTION: The thermal recording material includes as an electron acceptable compound an anthranilic acid derivative expressed by formula I and an anthranilic acid derivative expressed by formula II. In the formula, R1 shows an aryl group or an alkyl group; however, these groups may further include a substitutent, and as R1, there are given a 6-13C alkyl group, a 7-9C aryl oxy- alkyl group, a 7-9C arylalkyl group or the like. Furthermore, in the formula, as a group indicated by R2, it is preferable to be a 6<=C unsubstituted aryl group, a 6-9C aryl group substituted by an alkyl group, or the like. Besides, an addition quantity of such an electron acceptable compound is preferable to be 50-400 wt.% relative to an electron donative achromatic dye.

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 recording material capable of forming an image having an excellent black color tone, having good color stability and storage stability of a color image. About.

[0002]

2. Description of the Related Art Recording materials using an electron-donating colorless dye and an electron-accepting compound include pressure-sensitive paper, heat-sensitive paper, photosensitive pressure-sensitive paper,
It is already well known as a heat-sensitive recording paper and a thermal transfer paper. For example, British Patent 2,140,449, US Patent 448
No. 0052, No. 4436920, Japanese Patent Publication No. 60-239
No. 92, JP-A-57-179636 and JP-A-60-123
Nos. 556 and 60-123557. In recent years, as recording materials, researches on (1) improvement in characteristics such as color density and color sensitivity (2) storage stability of non-image areas and image areas have been earnestly conducted. Conventional electron-accepting compounds for electron-donating colorless dyes include bisphenol A,
Various types are known, such as p-hydroxybenzoic acid esters and bis- (4-hydroxyphenyl) sulfones.
All of them had some drawbacks in color density, color sensitivity, storage stability of non-image area and image area (weather resistance, chemical resistance, plasticizer resistance) and the like. For example, a heat-sensitive recording material using bis- (3-phenyl-4-hydroxyphenyl) sulfone has a problem that the background portion is fogged when writing with a highlighter pen.

[0003] These thermal recording systems are applied to various fields such as facsimile machines, printers and labels, and their needs are increasing. However, the heat-sensitive recording material is disadvantageous in that fogging is caused by a solvent or the like, and the color forming body is oil or fat,
Due to the drawback of discoloration due to chemicals and the like, in the fields of labels, slips, word processing paper, plotter paper, and the like, the commercial value has been significantly impaired. In addition, thermosensitive recording materials often perform recording in a single black color, but in the combination of an electron-donating colorless dye and an electron-accepting compound that are usually used as a coloring component of a thermosensitive coloring layer, a black color called real black is generated. It is difficult to obtain, and it becomes a reddish black image or a greenish black image, especially in a black solid portion, and it has been desired to form a black color image excellent in color tone.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide high stability of color density and storage stability such as chemical resistance of an image area and a non-image area. An object of the present invention is to provide a thermosensitive recording material having good properties and capable of forming a black image having an excellent color tone.

[0005]

Means for Solving the Problems The present inventors have studied each of an electron-donating colorless dye and an electron-accepting compound, pursued the development of a good recording material and a recording material, and completed the present invention. did. That is, the heat-sensitive recording material of the present invention is a heat-sensitive recording material in which a heat-sensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support, wherein the electron-accepting compound has the following general formula (1) ) And an anthranilic acid derivative represented by the following general formula (2).

[0006]

Embedded image (In the formula, R ¹ represents an aryl group or an alkyl group.)

[0007]

Embedded image (In the formula, R ² represents an aryl group.)

Here, as the anthranilic acid derivative, a preferred embodiment is an anthranilic acid derivative represented by the following general formula (3) and an anthranilic acid derivative represented by the following (4).

[0009]

Embedded image (In the formula, R ³ represents a hydrogen atom, a methyl group, or a methoxy group.)

[0010]

Embedded image (In the formula, R ⁴ represents a hydrogen atom, a methyl group, or a methoxy group.) The thermosensitive coloring layer preferably contains a zinc compound, particularly zinc oxide, and is used in combination with the electron-accepting compound. Preferred examples of the electron-donating colorless dye to be used include a compound represented by the following general formula (5).

[0011]

Embedded image (Wherein, R ^5, R ⁶ each independently represent a hydrogen atom, an alkyl group or an aryl group, further R ⁵ and R ⁶ may also form a heterocyclic ring bonded to each other .R ^7, R ⁸ is Each independently represents a hydrogen atom, an alkyl group or an aryl group; R ⁹ represents a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group or a halogen atom)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The heat-sensitive recording material of the present invention is characterized by containing an anthranilic acid derivative represented by the general formula (1) and an anthranilic acid derivative represented by the general formula (2) as electron-accepting compounds. Hereinafter, the anthranilic acid derivative will be described.

In the general formula (1), R ¹ represents an aryl group or an alkyl group. These groups may further have a substituent, and R ¹ preferably has 6 carbon atoms. Substituted with an alkyl group having 7 to 13 carbon atoms, an aryloxyalkyl group having 7 to 9 carbon atoms, an arylalkyl group having 7 to 9 carbon atoms, an alkyl group having 6 to 9 carbon atoms, or an alkoxy group having 6 to 9 carbon atoms. Aryl group. In the general formula (2), examples of the group represented by R ² include an unsubstituted aryl group having 6 to 6 carbon atoms, an aryl group substituted with an alkyl group having 6 to 9 carbon atoms, An aryl group substituted with an alkoxy group having 6 to 9 atoms is preferable.

A more preferred embodiment of the anthranilic acid derivative represented by the general formula (1) is an anthranilic acid derivative represented by the general formula (3). In the general formula (3), R ³ is hydrogen. An atom and a p-substituted methyl group,
P-substituted methoxy groups are preferred. Further, as a more preferred embodiment of the anthranilic acid derivative represented by the general formula (2), an anthranilic acid derivative represented by the general formula (4) is mentioned. In the general formula (4), R ⁴ is a hydrogen atom. And a p-substituted methyl group.

Hereinafter, specific examples of the anthranilic acid derivative represented by the above general formulas (1) and (2) will be shown, but the present invention is not limited to these. [Anthranilic acid derivative represented by general formula (1)] 1.2- (benzoylamino) benzoic acid 2.2- (p-methylbenzoylamino) benzoic acid 3.2- (p-methoxybenzoylamino) benzoic acid 4.2- (p-ethylbenzoylamino) benzoic acid 5.2- (p-ethoxybenzoylamino) benzoic acid 6.2- (p-propylbenzoylamino) benzoic acid 7.2- (m-methylbenzoylamino) Benzoic acid 8.2- (o-Methylbenzoylamino) benzoic acid 9.2- (Phenoxyacetylamino) benzoic acid 10.2- (α-phenoxypropionylamino) benzoic acid 11.2- (α-phenoxybutanoylamino) ) Benzoic acid 12.2- (Phenylacetylamino) benzoic acid 13.2- (Hexylcarbonylamino) benzoic acid 14.2 (Heptylcarbonylamino) benzoic acid 15.2- (nonylcarbonylamino) benzoic acid 16.2- (undecylcarbonylamino) benzoic acid 17.2- (dodecylcarbonylamino) benzoic acid [represented by the general formula (2) Anthranilic acid derivative] 18.2- (Phenylsulfonylamino) benzoic acid 19.2- (p-methylphenylsulfonylamino) benzoic acid 20.2- (m-methylphenylsulfonylamino) benzoic acid 21.2 .- (o -Methylphenylsulfonylamino) benzoic acid 22.2- (p-chlorophenylsulfonylamino) benzoic acid 23.2- (p-ethylphenylsulfonylamino) benzoic acid 24.2- (p-methoxyphenylsulfonylamino)
Benzoic acid 25.2- (p-ethoxyphenylsulfonylamino)
Benzoic acid 26.2- (p-butoxyphenylsulfonylamino)
Benzoic acid 26.2- (β-naphthylsulfonylamino) benzoic acid

The general formulas (1) and (2) according to the present invention
Each of the anthranilic acid derivatives represented by may be used alone, or two or more may be used in combination. The use ratio of the anthranilic acid derivative represented by the general formulas (1) and (2) according to the present invention is 10:90 by weight.
~ 90: 10, preferably 20:80
~ 80: 20 is more preferred, most preferably 4
The range is from 0:60 to 60:40. When the use ratio of either one of the anthranilic acid derivatives is less than 10% by weight, it is difficult to obtain excellent chemical resistance and black color tone, so that the effect obtained by using both in combination becomes insufficient.

In the heat-sensitive recording material of the present invention, the amount of the electron-accepting compound added to the heat-sensitive coloring layer is preferably 50 to 400% by weight, more preferably 100 to 400% by weight, based on the color of the electron-donating colorless dye. ~ 300% by weight is preferred.

In the thermosensitive coloring layer according to the present invention, in addition to the electron accepting compound comprising the above specific anthranilic acid derivative, other known electron accepting compounds may be used in combination as long as the effects of the present invention are not impaired. Can also. Known electron-accepting compounds that can be used in combination include phenol derivatives, phenolic resins, novolak resins, metal-treated novolak resins, metal complexes, salicylic acid derivatives, metal salts of aromatic carboxylic acids, acid clay, bentonite, and the like. Examples of these are Japanese Patent Publication No. 40-9309 and Japanese Patent Publication No. 45
-14039, JP-A-52-140483, JP-A-48-51510, JP-A-57-210886, JP-A-58-87089, JP-A-59-11286,
JP-A-60-177695, JP-A-61-95988
JP-A-63-65779, JP-A-6-72984
And JP-A-7-278098.
When another electron accepting compound is used in combination, the total content of the anthranilic acid derivative according to the present invention is preferably 50% or more, particularly preferably 60% or more, of all the electron accepting compounds.

As the electron-donating colorless dye that can be used in the present invention, conventionally known dyes can be used. Specifically, triphenyl methanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, leuco auramine compounds, rhodamine lactam compounds, triphenyl methane compounds, triazene compounds, spiropyrans And various compounds such as pyridine compounds, fluorene compounds, pyridine compounds and pyrazine compounds. Specific examples of the phthalides are described in U.S. Reissue Patent No. 23,024, U.S. Patent Nos. 3,491,111 and 3,491,112.
Nos. 3,491,116 and 3,509,
No. 174, specific examples of fluorans are disclosed in US Pat.
No. 4,107, No. 3,627,787, No. 3,6
No. 41,011, No. 3,462,828, No. 3,
Nos. 681,390, 3,920,510 and 3,959,571. Specific examples of spiropyrans are described in U.S. Pat. No. 3,971,808, and pyridine and pyrazine compounds are described in U.S. Pat. 3,775,424, 3,853,869 and 4,246,318, and specific examples of fluorene compounds are described in JP-A-63-94878. In the present invention, an electron-donating colorless dye represented by the general formula (5) is particularly preferable.

In the general formula (5), R^Five, R⁶Each
Independently represent a hydrogen atom, an alkyl group or an aryl group.
And then R^FiveAnd R⁶Are bonded to each other to form a ring
good. R⁷, R⁸Are each independently a hydrogen atom, an alkyl
Represents a group or an aryl group. R ⁹Is hydrogen atom, alkyl
Group, aryl group, alkyloxy group or halogen atom
Represents

Here, R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹
May further have a substituent. R ⁵ , R
^6, the alkyl group represented by R ^7, R ⁸ or R ^9, preferably an alkyl group having 1 to 10 carbon atoms, which may have a substituent group, and a linear Even, even if cyclic, may have a branched chain, specifically, for example, methyl, ethyl, propyl, octyl,
Decyl, methoxyethyl, ethoxyethyl, methoxypropyl, methoxyethoxyethyl, ethoxycarbonylmethyl, 2-chloroethyl, 2- (1,3-dichloropropyl), isopropyl, 3-heptyl, cyclopentyl, methylcyclohexyl, cyclohexyl, cyclodecyl, adamantyl Benzyl, phenethyl and the like. The aryl group represented by R ⁵ , R ⁶ , R ⁷ , R ⁸ or R ⁹ has 6 to 6 carbon atoms which may have a substituent.
Preferred are 20 aryl groups, such as phenyl, tolyl, chlorophenyl, 1-naphthyl, 2-naphthyl and the like.

The halogen atom represented by R ⁹ is preferably a chlorine atom or a bromine atom. The alkyl group represented by R ^9, preferably an alkyl group having 1 to 20 carbon atoms, such as methoxy, ethoxy, propyloxy, methoxy ethoxy, dodecyloxy, benzyloxy, and p-methoxybenzyloxycarbonyl and the like.

Preferred of these are 2-arylamino-3-H, halogen, alkyl or alkyloxy-6-substituted aminofluorans. As specific examples, for example, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6- (N
-Cyclohexyl-N-methylamino) fluoran, 2
-P-chloroanilino-3-methyl-6-dibutylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-anilino-3-methyl-6
(N-ethyl-N-isoamylamino) fluoran, 2
-Anilino-3-methyl-6- (N-ethyl-N-dodecylamino) fluoran, 2-anilino-3-methoxy-6-dibutylaminofluoran, 2-o-chloroanilino-6-dibutylaminofluoran, 2 -Anilino-
3-pentadecyl-6-diethylaminofluoran, 2
-Anilino-3-ethyl-6-dibutylaminofluoran, 2-o-toluidino-3-methyl-6-diisopropylaminofluoran, 2-anilino-3-methyl-6
-(N-isobutyl-N-ethylamino) fluoran,
2-anilino-3-methyl-6- (N-ethyl-N-tetrahydrofurfurylamino) fluoran, 2-anilino-3-chloro-6- (N-ethyl-N-isoamylamino) fluoran, 2-anilino- 3-methyl-6
(N-methyl-N-γ-ethoxypropylamino) fluoran, 2-anilino-3-methyl-6-N-ethyl-
N-γ-ethoxypropylaminofluoran, 2-anilino-3-methyl-6- (N-ethyl-N-γ-propoxypropylamino) fluoran, 2-anilino-3-
Methyl-6- (N-methyl-N-propylamino) fluoran and the like.

Particularly, 2-anilino-3-methyl-6-dialkylaminofluoran is preferable, and 2-anilino-
3-methyl-6-dibutylaminofluoran, 2-anilino-3-methyl-6- (N-ethyl-N-propylamino) fluoran, 2-anilino-3-methyl-6-dihexylaminofluoran, 2- Anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-
Methyl-6- (N-ethyl-N-isoamyl) aminofluoran and 2-anilino-3-methyl-6- (N-ethyl-N-isobutyl) aminofluoran are particularly preferred.

The thermosensitive coloring layer according to the present invention preferably contains a zinc compound from the viewpoint of image stability.
Examples of the zinc compound that can be used in the present invention include zinc oxide, zinc hydroxide, zinc carbonate, zinc phosphate, zinc silicate, and the like, with zinc oxide being particularly preferred. Usually, the use amount of the zinc compound is preferably from 10 to 400% by weight, more preferably from 50 to 300% by weight, based on the electron-accepting compound. If the amount is less than 10% by weight, the effect of the addition is insufficient, and if the amount is more than 400% by weight, the effect is not improved, and the dispersion stability in the coating solution for the thermosensitive coloring layer is rather reduced. is there.

Next, a method for adjusting the thermosensitive coloring layer in the thermosensitive recording material of the present invention will be described. In the preparation of the coating solution for the heat-sensitive coloring layer, the specific anthranilic acid derivative is usually used in a dispersion medium at 10 μm or less, preferably 3 μm or less.
It is used after being pulverized and dispersed to a particle size of not more than m. In this adjustment, the compound represented by the general formula (1) and the compound represented by the general formula (2)
With the compound represented by may be mixed separately dispersion liquid may be dispersed simultaneously in the same dispersion medium,
From the standpoint of performance, those dispersed at the same time are preferred. In addition, as described above, when a zinc compound is contained in the thermosensitive coloring layer, it is preferable to simultaneously disperse the zinc compound when dispersing the electron-accepting compound from the viewpoint of improving the performance. As the dispersion medium used for preparing the coating solution for the thermosensitive coloring layer, an aqueous solution of a water-soluble polymer having a concentration of about 0.5 to 10% is generally used. Examples of the water-soluble polymer include polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic acid salicylic acid copolymer, Polyacrylic acid,
Examples thereof include polyacrylamide, methylol-modified polyacrylamide, starch derivatives, casein, and gelatin. Water is preferred as these solvents. If the concentration of the water-soluble polymer is too low, the viscosity of the dispersion medium decreases, and the dispersed particles tend to precipitate.If it is too high, the viscosity of the coating liquid increases, and uniform coating becomes difficult, resulting in poor handling properties. I do. Dispersion can be performed using a known dispersing device such as a ball mill, a sand mill, a horizontal sand mill, an attritor, a colloidal mill and the like.

The coating amount of the electron-accepting compound according to the present invention is appropriately selected according to the desired properties of the heat-sensitive recording material, but is generally 0.1 to 2.0 g / m ² , particularly preferably 0.1 to 2.0 g / m ² . 0.
² to 1.5 g / m ² is preferred.

The heat-sensitive recording material of the present invention is disclosed in JP-B-59-5-5.
3193, JP-A-59-197463, JP-A-62
It takes the form as described in US Pat.

Similarly, the electron-donating colorless dye in the thermosensitive coloring layer coating solution is preferably a solid dispersion ground and dispersed in a dispersion medium to a particle size of 10 μm or less, preferably 3 μm or less. As the dispersion medium, those similar to those used for dispersing the electron-accepting compound can be used.

The amount of the electron-donating colorless dye according to the present invention is not particularly limited, but is generally 0.05 to 1 g / g.
m ² , particularly preferably 0.1 to 0.5 g / m ² .

Further, the thermosensitive coloring layer according to the present invention can contain a thermoplastic substance in order to improve the thermal response. Typical examples of the heat-fusible substance include aromatic ethers, thioethers, esters, and / or aliphatic amides or ureides. Examples of these thermoplastic materials are described in JP-A-58-57989 and JP-A-58-879.
Nos. 094, 61-58789, 62-10968
No. 1, 62-132677, 63-151478
And No. 63-235961. Although the thermoplastic substance may be used alone and dispersed, it may be used in the thermosensitive coloring layer as a finely dispersed dispersion together with the electron-donating colorless dye or the electron-accepting compound. The addition amount is from 20% by weight to 300% based on the electron-accepting compound.
% By weight, and particularly preferably in the range of 40% by weight to 150% by weight.

In order to further satisfy various requirements, known additives can be added to the thus-obtained thermosensitive coloring layer coating solution as long as the effects of the present invention are not impaired. . Examples of the additive include an inorganic pigment for preventing the recording head from being stained during recording, an oil-absorbing substance such as a polyurea filler, a fatty acid for improving the releasability from the head, and a metal soap. Therefore,
Generally, an electron-donating colorless dye that is a color-forming component, an electron-donating compound, and the above-described heat-fusible substance that is optionally added, a pigment, a metal soap, a wax, an antistatic agent, an ultraviolet absorber, an antifoaming agent, Additives such as a conductive agent, a fluorescent dye and a surfactant are appropriately mixed to prepare a thermosensitive coloring layer coating solution.

Hereinafter, additives that can be added to the thermosensitive coloring layer will be described. Pigments used as additives include kaolin, calcined kaolin, talc, fluorite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone, Examples include silica, magnesium carbonate, titanium oxide, alumina, barium carbonate, barium sulfate, mica, microballoons, urea-formalin filler, polyester particles, and cellulose filler.

Examples of the metal soap include polyvalent metal salts of higher fatty acids, for example, zinc stearate, aluminum stearate, calcium stearate, zinc oleate and the like.

In the present invention, wax having a melting point of 40 to 120 ° C. may be used from the viewpoint of head matching with a facsimile. As the wax, a wax having a melting point of 40 to 120 ° C, preferably a paraffin wax, a polyethylene wax, a carnauba wax, a microcrystalline wax, a candy wax, a montan wax, or a fatty acid amide wax, particularly, a paraffin having a melting point of 50 to 100 ° C is preferred. Wax, montan wax and methylol stearamide are preferred. The amount of wax used is 5 to 2 of the electron donating colorless dye.
00% by weight, preferably 20 to 150% by weight.

As the hindered phenol compound, a phenol derivative in which at least one of the 2- or 6-position is substituted with a branched alkyl group is preferable. UV absorbers include cinnamic acid derivatives, benzophenone derivatives,
Benzotriazole phenol derivatives and the like, for example, butyl α-cyano-β-phenylcinnamate, o-benzotriazole phenol, o-benzotriazole-p-chlorophenol, o-benzotriazole-2,4-di-t
-Butylphenol, o-benzotriazolyl-2,4
-Di-t-octylphenol and the like.

As the water-proofing agent, N-methylol urea,
Water-soluble precondensates such as N-methylolmelamine, urea-formalin, glyoxal, dialdehyde compounds such as glutaraldehyde, boric acid, inorganic crosslinking agents such as borax,
Blend heat-treated products of polyacrylic acid, methyl vinyl ether-maleic acid copolymer, isobutylene-maleic anhydride copolymer and the like can be mentioned.

The obtained thermosensitive coloring layer coating solution may be used for paper supports such as woodfree paper, coated paper obtained by applying resin or pigment to paper, resin laminated paper, woodfree paper having an undercoat layer, synthetic paper, plastic film, etc. It is applied to a support to form a thermosensitive coloring layer. At this time, Jls-
Smoothness specified by 8119 is 500 seconds or more, especially 800
It is particularly preferable to use a smooth one for seconds or more from the viewpoint of dot reproducibility.

When an undercoat layer is provided on a support, an undercoat layer containing a pigment as a main component is preferable. As the pigment, any of general organic or inorganic pigments can be used. In particular, the oil absorption specified by JIS-K5101 is 40 cc /.
It is preferably 100 g or more, specifically, calcium carbonate, barium sulfate, titanium oxide, talc, wax, kaolin, calcined kaolin, aluminum hydroxide, amorphous silica, urea formalin resin powder, polyethylene resin powder and the like. No. When these pigments are applied to a support, the amount of the pigment is 2 g / m ² or more, preferably 4 g / m ² or more.
g / m ² or more.

As the binder used for the undercoat layer,
Examples thereof include a water-soluble polymer and a water-soluble binder, and these may be used alone or in combination of two or more. Examples of the water-soluble polymer include methyl cellulose, carboxymethyl cellulose, hydroxytyl cellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, Examples include polyvinyl alcohol and polyacrylamide.

As the water-soluble binder, a synthetic rubber latex or a synthetic resin emulsion is generally used.
Examples include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. The amount of the binder used is 3 to 100% by weight, preferably 5 to 5% by weight, based on the pigment added to the undercoat layer.
0% by weight. Wax, decoloring inhibitor,
A surfactant or the like may be added.

In the heat-sensitive recording material of the present invention, a protective layer can be further formed on the heat-sensitive coloring layer. Two or more protective layers may be laminated as necessary. Materials used for the protective layer include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins, gum arabic, casein, Styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half-ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sodium sulfonate, sodium alginate Water-soluble polymers such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, acetic acid Water-insoluble polymer such as a sulfonyl emulsion is used.

In the protective layer, a pigment, a metal soap, a wax, a waterproofing agent and the like may be added for the purpose of improving the matching property with the thermal head. Further, when applying the protective layer on the thermosensitive coloring layer, a surfactant may be added in order to obtain a uniform protective layer. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant, and the like are preferably used, and specifically, di- (n-hexyl) sulfosuccinic acid, di- (2-ethylhexyl) sulfosuccinic acid, and the like. Or an ammonium salt thereof is preferable, but an effect can be obtained with an anionic surfactant.

In the heat-sensitive recording material of the present invention, a coating liquid similar to the protective layer is applied to the back surface to correct the curl balance of the support or to improve the chemical resistance from the back surface. A coat layer may be formed, and if desired, an adhesive may be applied to the back surface, and a release paper may be combined to form a label.

The heat-sensitive recording material of the present invention is not only excellent in the storage stability of the color image, but also in the stability of the color development, in particular, the uniformity of the color density under different humidity environments, and the uniformity of the color tone in the images with different color densities. Excellent in scratch resistance and scratch resistance (rub fog when the surface is strongly rubbed with a nail or the like). Further, even when the heat-sensitive recording material is handled with bare hands, absorption into the body from the skin or the like is scarcely recognized, and the material has excellent environmental and safety characteristics. Further, the color image of the heat-sensitive recording material of the present invention has an excellent effect of having a good black color tone which has not been obtained conventionally. In addition, as described above, despite having excellent performance, compared with a conventionally known heat-sensitive recording material having excellent image storability, the amount of expensive coloring material used can be reduced, and the cost is extremely low. There is a feature that there is.

[0046]

EXAMPLES The present invention will be described below in detail with reference to Examples, but the present invention is not limited to the following Examples. Unless otherwise specified, "part" and "%" in the examples
Indicates “parts by weight” and “% by weight”, respectively.

(Example 1) [Formation of thermosensitive coloring layer] (1) Preparation of solution A 10 parts of 3-dibutylamino-6-methyl-7-anilinofluoran 2.5% solution of polyvinyl alcohol (PVA-105) 50 parts of the above components were dispersed in a ball mill for 24 hours to obtain a solid dispersion of an electron-donating colorless dye (solution A) having an average particle size of 1.0 μm. (2-1) Preparation of B1 solution Electron-accepting compound of compound example 1 (compound of general formula (1)) 10 parts Polyvinyl alcohol 2.5% solution (PVA-105) 50 parts The above components are dispersed in a ball mill all day and night. Thus, an electron-accepting compound solid dispersion (solution B1) having an average particle size of 1.0 μm was obtained. (2-2) Preparation of B2 solution Electron-accepting compound of compound example 19 (compound of general formula (2)) 10 parts Zinc oxide 5 parts Polyvinyl alcohol 2.5% solution (PVA-105) 50 parts The above components were ball-milled. For one day to obtain an electron-accepting compound solid dispersion (solution B2) having an average particle size of 1.0 μm. (3) Solution C preparation 2-benzyloxynaphthalene 20 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 parts The above components were dispersed all day and night by a ball mill, and the average particle diameter was 1.0 μm. A compound dispersion (liquid C) was obtained. (4) Preparation of Liquid D 40 parts of light calcium carbonate 1 part of sodium polyacrylate 60 parts of water The above components were dispersed using a sand mill to obtain a pigment dispersion liquid (liquid D) having an average particle diameter of 2.0 μm.

Liquid A 60 parts, Liquid B1 60 parts, Liquid B2 6
5 parts, 120 parts of the liquid C, 101 parts of the liquid D, and 25 parts of a 21% dispersion of zinc stearate were mixed to obtain a thermosensitive coloring layer coating liquid. The obtained coating solution for a heat-sensitive coloring layer is applied to a 50 g / m ² undercoat base paper provided with an undercoat layer mainly composed of a pigment and a binder by a bar coat so as to have an application amount of 5 g / m ² , dried and calendered. Then, a heat-sensitive recording material was obtained.

[Formation of Protective Layer] (1) Preparation of Protective Layer Coating Solution Polyvinyl Alcohol (PVA105: Kuraray) 10% aqueous solution 200 parts Aluminum hydroxide 20 parts Zinc stearate 21% dispersion 19 parts Water 65 parts The layer coating solution was applied on the thermosensitive coloring layer with an air knife coat at 3 g / m ² and dried to obtain a thermosensitive recording material of Example 1.

Example 2 The electron accepting compound (compound of the general formula (1)) of the compound example 1 in the solid dispersion (solution B1) of the electron accepting compound of the example 1 was replaced with the electron accepting compound of the compound example 2. A heat-sensitive recording material of Example 2 was obtained in the same manner as in Example 1 except that the compound (the compound of the general formula (1)) was used.

(Example 3) The electron accepting compound (compound of the general formula (1)) of the compound example 1 in the solid dispersion (solution B1) of the electron accepting compound of the example 1 was replaced with the electron accepting compound of the compound example 9. A thermosensitive recording material of Example 3 was obtained in the same manner as in Example 1 except that the compound (the compound of the general formula (1)) was used. (Example 4) The electron accepting compound (compound of general formula (2)) of Compound Example 19 in the solid dispersion liquid (B2 liquid) of the electron accepting compound of Example 1 was replaced with the electron accepting compound of Compound Example 18 (General A thermal recording material of Example 4 was obtained in the same manner as in Example 1 except that the compound of the formula (2) was used.

(Example 5) 10 parts of the electron accepting compound (compound of the general formula (1)) of the compound example 1 in the solid dispersion (solution B1) of the electron accepting compound of the compound of Example 1 were used.
5 parts of the electron accepting compound (compound of general formula (1)) and the electron accepting compound of compound example 9 (compound of general formula (1))
A thermosensitive recording material of Example 5 was obtained in the same manner as in Example 1 except that the mixture was 5 parts by weight. (Example 6) 10 parts of the electron accepting compound of the compound example 19 (the compound of the general formula (2)) in the solid dispersion (solution B2) of the electron accepting compound of the example 1 were replaced with the electron accepting compound of the compound example 18. A thermosensitive recording material of Example 6 was obtained in the same manner as in Example 1, except that 5 parts of the compound of the general formula (2) and 5 parts of Compound Example 19 were mixed.

(Example 7) (1) Preparation of Solution A 3-Dibutylamino-6-methyl-7-anilinofluoran 10 parts Polyvinyl alcohol 2.5% solution (PVA-105) 50 parts The above components were ball-milled. To obtain an electron-donating colorless dye solid dispersion (solution A) having an average particle size of 1.0 μm. (2-1) Preparation of solution B1 Preparation of solution B1 Electron-accepting compound of compound example 1 (compound of general formula (1)) 7 parts Polyvinyl alcohol 2.5% solution (PVA-105) 35 parts The above components were put in a ball mill. To obtain a solid dispersion (B1 solution) of an electron-accepting compound having an average particle size of 1.0 μm. (2-2) Preparation of B2 solution Electron-accepting compound of compound example 19 (compound of general formula (2)) 13 parts Zinc oxide 6.5 parts Polyvinyl alcohol 2.5% solution (PVA-105) 65 parts The mixture was dispersed day and night with a ball mill to obtain a solid dispersion of an electron-accepting compound (solution B2) having an average particle diameter of 1.0 μm. (3) Preparation of liquid C 20 parts 2-benzyloxynaphthalene 20 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 parts The above components were dispersed all day and night by a ball mill, and the average particle diameter was 1.0 μm. A compound dispersion (liquid C) was obtained. (4) Preparation of Liquid D 40 parts of light calcium carbonate 1 part of sodium polyacrylate 60 parts of water The above components were dispersed using a sand mill to obtain a pigment dispersion liquid (liquid D) having an average particle diameter of 2.0 μm. Liquid A 60
Parts, 42 parts of liquid B1, 84.5 parts of liquid B2, and 120 parts of liquid C.
Part, liquid D 101 parts, zinc stearate 21% dispersion liquid 25
The parts were mixed to obtain a thermosensitive coloring layer liquid. The obtained coating solution for the heat-sensitive coloring layer was coated on a 50 g / m ² undercoat base paper provided with an undercoat layer mainly composed of a pigment and a binder at a coating amount of 5 g / m ^2.
coating and drying a bar coating so as to m ^2, and calender treatment to obtain a heat-sensitive recording material of Example 7.

(Comparative Example 1) (1) Solution A preparation 3-Dibutylamino-6-methyl-7-anilinofluoran 10 parts Polyvinyl alcohol 2.5% solution (PVA-105) 50 parts The above components were ball milled To obtain an electron-donating colorless dye solid dispersion (solution A) having an average particle size of 1.0 μm. (2) Preparation of B1 solution Electron-accepting compound of compound example 1 (compound of general formula (1)) 20 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 parts The above components were dispersed in a ball mill for 24 hours. An electron-accepting compound solid dispersion (solution B1) having an average particle size of 1.0 μm was obtained. (3) Solution C preparation 2-benzyloxynaphthalene 20 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 parts The above components were dispersed all day and night by a ball mill, and the average particle diameter was 1.0 μm. A compound dispersion (liquid C) was obtained. (4) Preparation of Liquid D 40 parts of light calcium carbonate 1 part of sodium polyacrylate 60 parts of water The above components were dispersed using a sand mill to obtain a pigment dispersion liquid (liquid D) having an average particle diameter of 2.0 μm. Liquid A 60
Part, B1 solution 120 parts, C solution 120 parts, D solution 101 parts,
A thermosensitive coloring layer solution was obtained by mixing 25 parts of a 21% zinc stearate dispersion. The obtained coating solution for a heat-sensitive coloring layer is applied to a 50 g / m ² undercoat base paper provided with an undercoat layer mainly composed of a pigment and a binder by a bar coat so as to have an application amount of 5 g / m ² , dried and calendered. Thus, a heat-sensitive recording material of Comparative Example 1 was obtained.

(Comparative Example 2) (2) Preparation of B2 solution Electron accepting compound of compound example 19 represented by general formula (2) 20 parts Zinc oxide 10 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 Part The above components were dispersed day and night in a ball mill to obtain a solid dispersion of an electron-accepting compound (solution B2) having an average particle size of 1.0 μm. In adjusting the thermosensitive coloring layer coating solution, the B1 solution 120
The heat-sensitive recording material of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that 130 parts of the B2 liquid was used instead of the parts.

Comparative Example 3 (2) Preparation of Solution B Preparation of Solution B Electron-accepting compound (bisphenol A) 20 parts Zinc oxide 5 parts Polyvinyl alcohol 2.5% solution (PVA-105) 100 parts The above components were ball milled To obtain an electron accepting compound solid dispersion (solution B) having an average particle diameter of 1.0 μm. In the preparation of the thermosensitive coloring layer coating solution, 60 parts of the B1 solution,
A thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1, except that 130 parts of the B liquid was used instead of 65 parts of the B2 liquid. (Comparative Example 4) Instead of the electron-accepting compound (bisphenol A) in the electron-accepting compound solid dispersion liquid (solution B) of Comparative Example 3, 3,5-bis (α-methylbenzyl) sartyl was used as the electron-accepting compound. A heat-sensitive recording material of Comparative Example 4 was obtained in the same manner as in Comparative Example 3 except that 20 parts of acid was used.

With respect to the heat-sensitive recording materials obtained in Examples 1 to 7 and Comparative Examples 1 to 4, sensitivity, fogging, vinyl chloride resistance (PVC resistance), highlighter pen resistance, inkjet sheet resistance, Table 1 shows the results of evaluating each item of the color tone of the color image.

<Sensitivity> A thermal head (KJT-216-8MPD1) manufactured by Kyocera Corp.
Using a thermal printing apparatus having a pressure of 0 kg / cm ² , printing was performed with a pulse width of 2.1 ms using a pressure roll under the conditions of a head voltage of 24 V and a pulse period of 10 ms, and the print density was measured using a Macbeth reflection densitometer RD-918. Was measured. The higher the concentration, the better the sensitivity. <Fog> The background after being left in an environment of 60 ° C. for 24 hours was measured by Macbeth RD918. The lower the numerical value, the better the evaluation.

<PVC Resistance> A commercially available sheet made of vinyl chloride (polymer wrap) was brought into contact with a printing screen, and the residual concentration after standing at 25 ° C. for 24 hours was measured with Macbeth RD918 to calculate the residual ratio. The higher the numerical value, the better the evaluation. <Highlighter resistance> Writing was performed with a highlighter (Zebra Highlighter 2-Pink), and the fog on the surface of the heat-sensitive recording material was visually evaluated. The criteria were as follows.・ ・ ・: No fog is seen. Δ: Some fog is observed. ×: fog is clearly seen.

<Inkjet Sheet Resistance> An image printed with high quality by inkjet (EPSON MJ930C) is brought into contact with the surface of the heat-sensitive recording material at 25 ° C. 48
The residual rate after standing for a time was measured. <Color tone of color image> 10 × 1 in the same manner as in the sensitivity test
A black solid image of 0 mm was printed, and the color tone of the color image was visually evaluated. The criteria were as follows.・ ・ ・: Good black color tone (real black). Δ: Some redness and greenness are detected. X: Clearly red and green tinges are detected.

[0061]

[Table 1]

As is clear from the results shown in Table 1, the heat-sensitive recording materials obtained in the examples of the present invention have excellent color stability and sensitivity, and can provide a color image having a good black color tone. The color image was found to be excellent in PVC resistance, highlighter pen resistance, ink jet sheet resistance, etc., and storage stability was also good. In addition, when the cost of the coating solution for the thermosensitive coloring layer was estimated, it is known that the conventional product, for example, although having a slightly inferior color tone of a colored image, has excellent image storage stability equivalent to that of the thermosensitive recording material of the present invention. 4- (β-p-methoxyphenoxyethoxy) as an electron accepting compound
Compared with a thermosensitive recording material using salicylic acid, the coating solution cost was 50% or less, which proved to be extremely economically advantageous.

According to the heat-sensitive recording material of the present invention, the stability of color density is high, the storage stability such as the chemical resistance of the image area and the non-image area is good, and a black image having excellent color tone is obtained. The excellent effect that can be formed can be achieved.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Iwakura 200 Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo Film Co., Ltd. F term (reference) 2H026 AA07 BB14 BB15 BB37 DD04 DD19 DD32 DD53

Claims (5)

[Claims] 1. A heat-sensitive recording material comprising a support and a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound, wherein the anthranil represented by the following general formula (1) is used as the electron-accepting compound. A heat-sensitive recording material comprising an acid derivative and an anthranilic acid derivative represented by the following general formula (2). Embedded image (In the formula, R ¹ represents an aryl group or an alkyl group.) (In the formula, R ² represents an aryl group.) 2. The thermosensitive recording according to claim 1, wherein the anthranilic acid derivative is an anthranilic acid derivative represented by the following general formula (3) and an anthranilic acid derivative represented by the following formula (4). material. Embedded image (In the formula, R ³ represents a hydrogen atom, a methyl group, or a methoxy group.) (In the formula, R ⁴ represents a hydrogen atom, a methyl group, or a methoxy group.) 3. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive coloring layer contains a zinc compound. 4. The heat-sensitive recording material according to claim 3, wherein the zinc compound is zinc oxide. 5. The heat-sensitive recording material according to claim 1, wherein the electron-donating colorless dye contains a compound represented by the following general formula (5). Embedded image (Wherein, R ^5, R ⁶ each independently represent a hydrogen atom, an alkyl group or an aryl group, further R ⁵ and R ⁶ may also form a heterocyclic ring bonded to each other .R ^7, R ⁸ is Each independently represents a hydrogen atom, an alkyl group or an aryl group; R ⁹ represents a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group or a halogen atom)