JP2000006531A - 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 an image part and nonimage part such as an chemical resistance, and an excellent hue by having an electron acceptable compound in a bisphenol sulfone derivative and an anthranilic acid derivative expressed by a specific formula. SOLUTION: The thermal recording material contains as an electron acceptable compound a bisphenol sulfone derivative expressed by formula I, an anthranilic acid derivative expressed by formula II, and an anthranilic acid drivative expressed by formula III. In the formula, if R1 is a hydrogen atom, X is preferably an aryl group or phenol group, and if R1 is a substance other than an hydrogen atom, X is preferably a hydrogen atom. In the formula II, R2 shows an aryl group or an alkyl group. In the formula III, R3 shows an aryl group. Besides, an addition amount of the electron acceptable compound is preferably 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) ), An anthranilic acid derivative represented by the following general formula (2), and an anthranilic acid derivative represented by the following general formula (3).

[0006]

Embedded image (In the formula, R ¹ represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryloxyalkyl group, and X represents a hydrogen atom, an allyl group, or a phenyl group.)

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

Embedded image (In the formula, R ³ represents an aryl group.)

[0007] In addition, a zinc compound,
Particularly, it preferably contains zinc oxide, and as a preferable electron-donating colorless dye used in combination with the electron-accepting compound, a compound represented by the following general formula (4) is exemplified.

[0008]

Embedded image (Wherein, R ^4, R ⁵ are each independently a hydrogen atom, an alkyl group or an aryl group, further R ⁴ and R ⁵ may also form a heterocyclic ring bonded to each other .R ^6, R ⁷ is Each independently represents a hydrogen atom, an alkyl group or an aryl group; R ⁸ represents a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group or a halogen atom.

[0009]

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 includes, as electron accepting compounds, a bisphenolsulfone derivative represented by the general formula (1), an anthranilic acid derivative represented by the general formula (2), and a compound represented by the general formula (3). Characterized by containing an anthranilic acid derivative. Hereinafter, the bisphenol sulfone derivative will be described. In the general formula (1), when R ¹ is a hydrogen atom, X is preferably an allyl group or a phenyl group, and when R ¹ is other than a hydrogen atom, X is preferably a hydrogen atom. When R ¹ is other than a hydrogen atom, R ¹ is an alkyl group having 3 to 7 carbon atoms,
Preferable examples include a benzyl group which may have an alkyl group having 7 to 9 carbon atoms as a substituent and a phenoxyalkyl having 8 to 12 carbon atoms. Among them, when R ¹ is a hydrogen atom, X is preferably an allyl group, and when R ¹ is other than a hydrogen atom, X is a hydrogen atom, and R ¹ is, specifically,
Isopropyl, butyl, amyl, hexyl, benzyl, p-methylbenzyl, β-phenoxyethyl, and β-phenoxypropyl are particularly preferred. Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited thereto.

[Specific Examples of Bisphenolsulfone Derivative] 1. bis (3-allyl-4-hydroxyphenyl) sulfone 3. bis (3-phenyl-4-hydroxyphenyl) sulfone 3.4-hydroxyphenyl) (4-isopropoxyphenyl) sulfone (4-hydroxyphenyl) (4-n-butoxyphenyl) sulfone (4-hydroxyphenyl) (4-n-amyloxyphenyl) sulfone (4-hydroxyphenyl) (4-isoamyloxyphenyl) sulfone 7. (4-hydroxyphenyl) (4-benzyloxyphenyl) sulfone (4-hydroxyphenyl) (4-p-methylbenzyloxyphenyl) sulfone (4-hydroxyphenyl) (4-β-phenoxyethoxyphenyl) sulfone (4-Hydroxyphenyl) (4-β-phenoxypropoxyphenyl) sulfone Next, the anthranilic acid derivative represented by the general formula (2) or (3) will be described.

In the general formula (2), R ² represents an aryl group or an alkyl group. These groups may further have a substituent. R ² is preferably a group having 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 (3), as the group represented by R ³ , an unsubstituted aryl group having 6 to 10 carbon atoms, an aryl group substituted with an alkyl group having 7 to 9 carbon atoms, An aryl group substituted with an alkoxy group having 7 to 9 carbon atoms is preferred.

Hereinafter, specific examples of the anthranilic acid derivatives represented by the above general formulas (2) and (3) are shown, but the present invention is not limited to these. [Anthranilic acid derivative represented by general formula (2)] 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 (3) 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 27.2- (β-naphthylsulfonylamino) benzoic acid

The total use ratio of the phenol derivative represented by the general formula (1) and the anthranilic acid derivative represented by the general formulas (1) and (2) and (3) according to the present invention [( 1) :( 2) + (3)] is 1 in weight ratio.
It is preferably in the range of 0:90 to 90:10, and 2
The ratio is more preferably from 0:80 to 80:20, most preferably from 30:70 to 70:30. When the content of either one is less than 10% by weight, the stability of color development,
It is not preferable from the viewpoint of image storage stability. In addition, the anthranilic acid derivative according to the present invention requires the use of two kinds of those represented by the general formula (2) and those represented by the general formula (3), and is represented by the general formula (2). Examples thereof include an alkylcarbonyl group having 6 to 13 carbon atoms, an aryloxyalkylcarbonyl group having 7 to 9 carbon atoms,
An anthranilic acid derivative having an arylalkylcarbonyl group having 7 to 9 carbon atoms, an arylcarbonyl group which may be substituted with an alkyl group having 6 to 9 carbon atoms or an alkoxy group is preferable. More than one species may be used in combination. As the compound represented by the general formula (3), one or more of an anthranilic acid derivative having an arylsulfonyl group which may be substituted with an alkyl group or an alkoxy group having 6 to 9 carbon atoms is used. Is preferred. The usage ratio of the anthranilic acid derivative represented by the general formula (2) and the anthranilic acid derivative represented by the general formula (3) [(2) :( 3)] is arbitrary,
The weight ratio is preferably 10:90 to 90:10,
20: 80-80: 20 is more preferred, and 40: 60-
60:40 is particularly preferred. 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 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 phenol derivative according to the present invention and each of the anthranilic acid derivatives is at least 50%, especially 60%, of all the electron-accepting compounds.
% Is preferably used.

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

As the electron donating colorless dye which 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 (4) is particularly preferable.

In the general formula (4), R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group or an aryl group, and R ⁴ and R ⁵ may be bonded to each other to form a heterocyclic ring. . R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group or an aryl group. R ⁸ represents a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group or a halogen atom.

Here, R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸
May further have a substituent. R ⁴ , R
^{As the} alkyl group represented by ⁵ , R ⁶ , R ⁷ and R ⁸ , an alkyl group having 1 to 10 carbon atoms is preferable, and these may have a substituent and may have a straight-chain structure. 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 ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ 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 ⁸ is preferably a chlorine atom or a bromine atom. The alkyl group represented by R ^8, 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 examples 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 storability. 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 can be mentioned, and zinc oxide is particularly preferable. The amount of the zinc compound used is usually 10 to 400 with respect to the electron-accepting compound.
% By weight, more preferably 50 to 300% by weight. 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.

The electron accepting compound according to the present invention is usually pulverized in a dispersion medium to a particle size of 10 μm or less, preferably 3 μm or less, and used as a solid dispersion. In the electron accepting compound according to the present invention, the compound represented by the general formula (1), the compound represented by the general formula (2), and the compound represented by the general formula (3) may be separately dispersed. And may be dispersed at the same time, but in terms of performance, the compound represented by the general formula (1)
The compound represented by the general formula (2) and the compound represented by the general formula (3) are preferably dispersed separately in terms of performance. In the present invention, the electron-accepting compound represented by the general formula (2) and the compound represented by the general formula (3) may be dispersed at the same time or may be dispersed separately. At this time, it is preferable to simultaneously disperse at least one of the anthranilic acid derivative and the zinc compound from the viewpoint of improving the performance.

As a 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 from 0.1 to 2.0 g / m ² , particularly preferably from 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.
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 coating amount of the colorless electron-donating dye according to the present invention is not particularly limited, but is generally 0.05 to 1 g / color.
m ² , particularly preferably 0.1 to 0.5 g / m ² .

Further, the thermosensitive coloring layer according to the present invention may contain a thermoplastic substance for improving 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 higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

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.

The hindered phenol compound is preferably a phenol derivative in which at least one of the 2- or 6-position is substituted with a branched alkyl group. 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.

Examples of the water-proofing agent include 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 resulting 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, JIS-
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 preferred. 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 color stability, especially the uniformity of the color density in environments with different humidity, and the uniformity of the color tone in 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.

[0044]

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 3-dibutylamino-6-methyl-7-anilinofluoran 10 parts Polyvinyl alcohol 2.5% solution (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) B1 solution preparation Electron-accepting compound of compound example 1 represented by general formula (1) 10 parts Polyvinyl alcohol 2.5% solution (PVA-105) 50 parts The above components are dispersed day and night in a ball mill. 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 5 parts of electron accepting compound of compound example 1 represented by general formula (2) 5 parts of electron accepting compound of compound example 19 represented by general formula (3) 5 parts of zinc oxide 50 parts of a polyvinyl alcohol 2.5% solution (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-accepting compound having an average particle diameter of 1.0 μm (B2 liquid). (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.

Solution A 60 parts, Solution B1 60 parts, Solution 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.

Example 2 The electron accepting compound (compound of the general formula (2)) of the compound example 1 in the solid dispersion (solution B2) of the electron accepting compound of the example 1 was replaced with the electron accepting compound of the compound example 9. 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 (2)) was used.

(Example 3) In the heat-sensitive coloring layer coating solution of Example 1, 60 parts of A liquid, 55 parts of B1 liquid and 57.5 of B2 liquid were used.
A thermosensitive recording material of Example 2 was obtained in the same manner as in Example 1, except that 120 parts of solution C, 120 parts of solution C, 101 parts of solution D, and 25 parts of a 21% zinc stearate dispersion were mixed.

(Comparative Example 1) In the heat-sensitive coloring layer coating solution of Example 1, 60 parts of solution A, 110 parts of solution B1 and 120 parts of solution C were used.
Part, liquid D 101 parts, zinc stearate 21% dispersion liquid 25
A heat-sensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the parts were mixed. (Comparative Example 2) (2) B2 liquid preparation Electron-accepting compound of compound example 1 represented by general formula (2) 20 parts Zinc oxide 10 parts Polyvinyl alcohol 2.5% solution (PVA-105)
100 parts of the above components were dispersed day and night by a ball mill to obtain a solid dispersion of an electron-accepting compound (B1 solution) having an average particle size of 1.0 μm. In the thermosensitive coloring layer coating solution of Example 1, 60 parts of solution A, 115 parts of solution B2, and 120 parts of solution C were used.
Part, liquid D 101 parts, zinc stearate 21% dispersion liquid 25
A heat-sensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the parts were mixed.

For the heat-sensitive recording materials obtained in Examples 1 to 3 and Comparative Examples 1 and 2, according to the following criteria, sensitivity, fogging resistance, vinyl chloride resistance (PVC resistance), fluorescent pen resistance, ink jet 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 vinyl chloride sheet (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 a 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 an inkjet (EPSON MJ930C) is brought into contact with the surface of the heat-sensitive recording material at 25 ° C. for 48 hours.
The residual rate after standing for a time was measured.

[0054]

[Table 1]

As is evident from the results in Table 1, the heat-sensitive recording materials obtained in the examples of the present invention have excellent color stability and sensitivity, and the color images are resistant to PVC, fluorescent pen, and inkjet sheet. It was found that the storage stability was good. Further, the obtained image was a black image having an excellent color tone.

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 F-Film Co., Ltd. F-term (reference) 2H026 AA07 BB02 BB14 BB25 BB30 BB37 DD04 DD12 DD17 DD32 DD53 FF01

Claims (4)

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