JP2000006533A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the stability of coloring density, and render the preservative stability of an image part and nonimage part such as chemical resistance excellent by permitting an electron acceptable compound to contain a phenol derivative and a salicylic acid derivative expressed by a specific formula. SOLUTION: The thermal recording material contains as an electron acceptable compound a phenol derivative expressed as an electron acceptable compound by formulas I and a salicylic acid derivative expressed by formula II. In the formula I, R1, R2 show a hydrogen atom, an alkyl group or a halogen atom respectively independently, and R3, R4 show a hydrogen atom, an alkyl group, a halogen atom or a hydroxy group respectively independently. X shows a hydrogen atom, hydroxy group, or an alkyl group. In the formula II, R5 shows an aryloxyalkyloxy group. Besides, an addition amount of such a phenol derivative expressed by formula I and salicylic acid derivative expressed by formula II is preferably 50-400 wt.% with respect 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 heat-sensitive recording material having good color stability and excellent storage stability of a color image.

[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 No. 2,140,449, U.S. Patent Nos. 4,480,052, 4,436,920, JP-B-60-23992, JP-A-57-179636,
Nos. 60-123556 and 60-123557. In recent years, researches on the improvement of properties of recording materials such as (1) color density and color sensitivity (2) storage stability of non-image areas and image areas have been earnestly conducted. Conventionally, as an electron accepting compound for an electron donating colorless dye, bisphenol A, p-hydroxybenzoic acid esters, bis-
Various compounds such as (4-hydroxyphenyl) sulfones are known, but all of them are color density, color sensitivity, and storage stability of non-image areas (weather resistance, chemical resistance, plasticizer resistance).
Etc. had several disadvantages. For example, screw-
The heat-sensitive recording material using (3-phenyl-4-hydroxyphenyl) sulfone had a problem that the background portion was fogged when writing with a fluorescent 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 disadvantage that the heat-sensitive recording material causes fogging due to the solvent and the like, and the color forming body is oil and 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.

[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. It is intended to provide a heat-sensitive recording material having excellent properties.

[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. And a salicylic acid derivative represented by the following general formula (2).

[0006]

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(Wherein R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or a halogen atom;
R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group,
Represents a halogen atom or a hydroxy group. X represents a hydrogen atom, a hydroxy group, or an alkyl group. )

[0008]

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(In the formula, R ⁵ represents an aryloxyalkyloxy 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 (3).

[0010]

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[0011] (represents wherein each R ^6, R ⁷ independently represent a hydrogen atom, an alkyl group or an aryl group, further R ⁶
And R ⁷ may combine with each other to form a ring. R ⁸ , R
⁹ independently represents a hydrogen atom, an alkyl group or an aryl group. R ¹⁰ 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 a phenol derivative represented by the general formula (1) and a salicylic acid derivative represented by the general formula (2) as electron-accepting compounds. Hereinafter, the phenol derivative and the salicylic acid derivative will be described.

In the general formula (1), R¹, R^TwoEach
Independently a hydrogen atom, an alkyl group, or a halogen atom
And R^Three, R^FourAre each independently a hydrogen atom,
Represents a kill group, a halogen atom, or a hydroxy group. X
Represents a hydrogen atom, a hydroxy group, or an alkyl group.
R¹, R^Two, R^Three, R^Four, An alkyl group represented by X
For example, a lower alkyl group having 1 to 5 carbon atoms is preferable.
For example, methyl, ethyl, n-propyl, isopropyl
And a t-butyl group.
Also, R¹, R ^Two, R^Three, R^FourHalogen atom represented by
Include chlorine, bromine and iodine
However, among them, a chlorine atom and a bromine atom are preferable. This
Among these groups, R¹, R^Two, R^Three, R^Fouras,
A hydrogen atom and a methyl group are particularly preferred.
Hydrogen atoms are particularly preferred. Also, R¹, R^Two, R^Three, R
^FourMay be the same or different,
R¹, R^TwoAnd R^Three, R^FourIs preferably the same as
No.

In the general formula (2), R ⁵ represents an aryloxyalkyloxy group. Preferred examples of R ⁵ include aryloxyalkyloxy groups having 8 to 18 carbon atoms. Among them, the number of carbon atoms is 8 to
An aryloxyethoxy group which may be substituted with an alkyl group, halogen atom or alkoxy group of 18 is particularly preferred.

Hereinafter, specific examples of the phenol derivative represented by the general formula (1) and the salicylic acid derivative represented by the general formula (2) are shown, but the present invention is not limited thereto. [Phenol derivative represented by general formula (1)] 1) 2,4-bis (phenylsulfonyl) phenol 2) 2,4-bis (4-methylphenylsulfonyl)
Phenol 3) 2,4-bis (4-ethylphenylsulfonyl)
Phenol 4) 2,4-bis (4-isopropylphenylsulfonyl) phenol 5) 2,4-bis (2-methylphenylsulfonyl)
Phenol 6) 2,4-bis (4-chlorophenylsulfonyl)
Phenol 7) 2,4-bis (4-bromophenylsulfonyl)
Phenol 8) 2,4-bis (2,4-dimethylphenylsulfonyl) phenol 9) 2,4-bis (3,4-dimethylphenylsulfonyl) phenol 10) 2,4-bis (2,5-dimethylphenylsulfonyl) ) Phenol 11) 2,4-bis (phenylsulfonyl) -5-methylphenol 12) 2- (4-methylphenylsulfonyl) -4-
(Phenylsulfonyl) phenol 13) 2- (2,4-dimethylphenylsulfonyl)
4- (phenylsulfonyl) phenol 14) 2- (phenylsulfonyl) -4- (4-chlorophenylsulfonyl) phenol 15) 4,4′-dihydroxy-5- (phenylsulfonyl) diphenylsulfone 16) 2,4-bis (Phenylsulfonyl) resorcinol

[Salicylic acid derivative represented by general formula (2)] 1) 4- (2-phenoxyethoxy) salicylic acid 2) 4- (2-p-methylphenyloxyethoxy)
Salicylic acid 3) 4- (2-p-methoxyphenyloxyethoxy) salicylic acid 4) 4- (2-p-ethylphenyloxyethoxy)
Salicylic acid 5) 4- (2-p-ethoxyphenyloxyethoxy) salicylic acid 6) 4- (2-p-propylphenyloxyethoxy) salicylic acid 7) 4- (2-p-propoxyphenyloxyethoxy) salicylic acid 8) 4- (2-2-naphthyloxyethoxy) salicylic acid 9) 4- (2-m-methylphenyloxyethoxy)
Salicylic acid 10) 4- (2-p-chlorophenyloxyethoxy) salicylic acid 11) 4- (2-m-chlorophenyloxyethoxy) salicylic acid 12) 4- (2-o-chlorophenyloxyethoxy) salicylic acid 13) 4- (3- Phenoxypropoxy) salicylic acid 14) 4- (4-phenoxybutoxy) salicylic acid 15) 4- (5-phenoxypentyloxy) salicylic acid 16) 4- (6-phenoxyhexyloxy) salicylic acid

The phenol derivative represented by the general formula (1) and the salicylic acid derivative represented by the general formula (2) according to the present invention may be used alone or in combination of two or more. it can. The use ratio of the phenol derivative represented by the general formula (1) and the salicylic acid derivative represented by the general formula (2) according to the present invention is expressed in terms of weight ratio.
It is preferably in the range of 10:90 to 90:10,
The ratio is more preferably from 20:80 to 80:20, and still more preferably from 40:60 to 70:30. If the use ratio of any one of the phenol derivative and the salicylic acid derivative is less than 10% by weight, fog cannot be sufficiently prevented,
Since it is difficult to obtain excellent chemical resistance, the effect obtained by using both of them is insufficient.

In the heat-sensitive recording material of the present invention, the amount of the phenol derivative represented by the general formula (1) and the salicylic acid derivative represented by the general formula (2) to be added to the heat-sensitive color-forming layer depends on the electron-donating colorless color. It is preferably from 50 to 400% by weight, particularly preferably from 100 to 300% by weight, based on the dye.

In the thermosensitive coloring layer according to the present invention, in addition to the electron-accepting compound consisting of the specific phenol derivative and the specific salicylic acid derivative, other known electron-accepting compounds as long as the effects of the present invention are not impaired. Can also be used in combination. 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. These examples are shown in
No. 9309, JP-B-45-14039, JP-A-52-140.
140483, JP-A-48-51510, JP-A-5
7-210886, JP-A-58-87089, JP-A-59-11286, JP-A-60-176799,
JP-A-61-95988, JP-A-63-65797
JP-A-6-72984, JP-A-7-278098
No. etc. When other electron-accepting compounds are used in combination, the total content of the electron-accepting compounds according to the present invention is at least 50%, particularly preferably 60%, of all the electron-accepting compounds.
% Is preferably used.

As the electron donating colorless dye that can be used in the present invention, conventionally known dyes can be used. Specifically, triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide 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 following general formula (3) is particularly preferable.

[0021]

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In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group or an aryl group, and R ⁶ and R ⁷ may combine with each other to form a ring. R ⁸ , R ⁹
Each independently represents a hydrogen atom, an alkyl group or an aryl group. R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group,
Represents an alkyloxy group or a halogen atom.

Here, R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰
May further have a substituent. R ⁶ , R
^7, the alkyl group represented by R ^8, R ⁹ or R ^10, 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 ⁶ , R ⁷ , R ⁸ , R ⁹ or R ¹⁰ has 6 to 6 carbon atoms which may have a substituent.
Preferred are 20 aryl groups, for example, phenyl, tolyl, chlorophenyl, 1-naphthyl, 2-naphthyl and the like.

The halogen atom represented by R ¹⁰ is preferably a chlorine atom or a bromine atom. The alkyl group represented by R ^10, 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.

Preferable examples thereof are 2-arylamino-3-H, halogen, alkyl or alkyloxy-6-substituted aminofluoran. 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.

In particular, 2-anilino-3-methyl-6-dialkylaminofluoran is preferred, 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, with zinc oxide being particularly preferred. Usually, the amount of the zinc compound used is preferably from 10 to 400% by weight, more preferably from 50 to 300% by weight, based on the salicylic acid derivative. 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.

Further, the thermosensitive coloring layer according to the present invention may contain a heat-fusible compound in order to improve the thermal response. Typical examples of the heat-fusible compound include aromatic ethers, thioethers, esters and / or thermoplastic substances such as aliphatic amides or ureides. Examples of these thermoplastics are described in JP-A-58-5 / 58.
No. 7989, No. 58-87094, No. 61-5878
No. 9, No. 62-109681, No. 62-132677
Nos. 63-151478 and 63-235961. The amount of the heat-fusible compound to be added is from 20% by weight to 30% with respect to the electron-accepting compound.
It is preferably 0% by weight, and particularly preferably in the range of 40% by weight to 150% by weight.

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 thermosensitive coloring layer coating solution, the specific phenol derivative and the specific salicylic acid derivative, which are electron-accepting compounds,
Usually, it is used by being pulverized and dispersed in a dispersion medium to a particle size of 10 μm or less, preferably 3 μm or less. In this adjustment, the compound represented by the general formula (1) and the compound represented by the general formula (2) may be separately mixed with each other in a dispersion, or may be simultaneously dispersed in the same dispersion medium. However, from the viewpoint of performance, those dispersed at the same time are preferable.

As described above, when a zinc compound is contained in the heat-sensitive coloring layer, it is preferable to disperse the zinc compound at the same time as dispersing the salicylic acid derivative from the viewpoint of improving the performance. Further, the heat-fusible compound may be used alone and dispersed, but it can also be used in the thermosensitive coloring layer as a finely dispersed dispersion together with the electron-donating colorless dye or the electron-accepting compound.

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 anhydride 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.

Similarly, for the electron-donating colorless dye in the thermosensitive coloring layer coating solution, it is preferable to use 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.

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,
In general, an electron-donating colorless dye that is a color-forming component, an electron-donating compound, and the above-mentioned heat-fusible compound 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.

The additives which can be added to the thermosensitive coloring layer will be described below. 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.

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.

Examples of the water-proofing agent include N-methylol urea,
N-methylolmelamine, water-soluble precondensates such as 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 and the like. 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.

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 amount of the electron-donating colorless dye according to the present invention is not particularly limited, but is generally 0.05 to 1.0 g / m ² , particularly 0.1 to 1.0 g / m ² .
0.5 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.

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. Water-soluble polymers include methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, polyvinyl Alcohol, polyacrylamide and the like can be mentioned.

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 a color image, but also in the stability of color development, in particular, the uniformity of color density in environments with different humidity, and the uniformity of 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). Also,
As described above, in spite of 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. Has features.

[0049]

【Example】

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to only the following Examples. Unless otherwise specified, “parts” and “%” in the examples indicate “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% aqueous solution of polyvinyl alcohol (Kuraray PVA- 105) 50 parts The above components were placed in a ball mill and dispersed day and night to obtain an electron-donating colorless dye solid dispersion (solution A) having a volume average particle diameter of 1.0 μm. (2) Preparation of Solution B Electron-accepting compound of compound example 1 (compound of general formula (1)) 10 parts Electron-accepting compound of compound example 3 (compound of general formula (2)) 10 parts polyvinyl alcohol 2.5 % Aqueous solution (Kuraray PVA-105) 50 parts The above components were placed in a ball mill and dispersed throughout the day and night, and a solid dispersion of an electron-accepting compound having a volume average particle diameter of 1.0 μm (B
Liquid). (3) Preparation of liquid C 20 parts 2-benzyloxynaphthalene 20 parts Polyvinyl alcohol 2.5% aqueous solution (Kuraray PVA-105) 100 parts The above components were placed in a ball mill and dispersed day and night, and heat having a volume average particle diameter of 1.0 μm was obtained. A fusible compound dispersion liquid (liquid C) was obtained. (4) Preparation of Solution 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 (D solution) having a volume average particle diameter of 2.0 μm.

Each of the above dispersions, 60 parts of solution A, and 125 parts of solution B
Parts, 120 parts of liquid C, 101 parts of liquid D, and 25 parts of a 21% zinc stearate dispersion 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. By processing, a heat-sensitive recording material of Example 1 was obtained.

Example 2 The electron accepting compound (compound of the general formula (1)) of the compound example 1 in the solid dispersion (solution B) of the electron accepting compound of the example 1 was replaced with the electron accepting compound of the compound example 2. A thermosensitive 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 (2)) of the compound example 3 in the electron-accepting compound solid dispersion liquid (solution B) of the example 1 is replaced with the electron-accepting compound of the compound example 2 (general formula) A heat-sensitive recording material of Example 3 was obtained in the same manner as in Example 1 except that the compound (2) was used.

(Example 4) 12 parts of the electron accepting compound of the compound example 1 (compound of the general formula (1)) in the solid dispersion (solution B) of the electron accepting compound of the example 1 A heat-sensitive recording material of Example 4 was obtained in the same manner as in Example 1, except that the acceptor compound (the compound of the general formula (2)) was changed to 8 parts.

(Comparative Example 1) 10 parts of the electron accepting compound of the compound example 1 (compound of the general formula (1)) and the electron of the compound example 3 in the solid dispersion (solution B) of the electron accepting compound of the example 1. In the same manner as in Example 1 except that 20 parts of the electron accepting compound (compound of the general formula (1)) of Compound Example 1 was used instead of 10 parts of the accepting compound (the compound of the general formula (2))
A heat-sensitive recording material of Comparative Example 1 was obtained. (Comparative Example 2) 10 parts of the electron-accepting compound of the compound example 1 (compound of the general formula (1)) and the electron-accepting compound of the compound example 3 in the solid dispersion (solution B) of the electron-accepting compound of Example 1 Instead of 10 parts of the compound of the general formula (2), the electron accepting compound of the compound example 3 (the compound of the general formula (2)) 2
A thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that 0 part was used.

With respect to the heat-sensitive recording materials obtained in Examples 1 to 5 and Comparative Examples 1 and 2, items of sensitivity, fog, vinyl chloride resistance (PVC resistance), highlighter pen resistance, and ink jet sheet resistance were determined according to the following criteria. Table 1 shows the results of evaluating
Shown in

<Sensitivity> A thermal head (KJT-216-8MPD1) manufactured by Kyocera Corp.
Using a thermal printer 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 with a Macbeth reflection densitometer RD918. did. 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.

<Resistance to PVC> 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 by 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 heat-sensitive recording material surface was visually evaluated. The criteria were as follows. ○ ・ ・ ・ ・ No fog is seen. Δ: Some fog is seen. ×: Fog is clearly seen. <Inkjet sheet resistance> Inkjet (EPS
ON MJ930C), the image printed with high quality and the surface of the heat-sensitive recording material were brought into contact with each other, and the residual ratio after standing at 25 ° C. for 48 hours was measured.

[0059]

[Table 1]

As is clear from the results shown in Table 1, the compound of the general formula (1) alone has much fog and is inferior in chemical resistance (Comparative Example 1). In addition, the compound of the general formula (2) alone is sufficient in performance such as color stability, sensitivity, fog, and chemical resistance (Comparative Example 2), but has the general formula (1).
It can be seen that further improvement in sensitivity, fog, and chemical resistance can be seen by using the compound of formula (2) in combination with the compound of formula (2). As a result, the amount of 4- (β-p-methoxyphenoxyethoxy) salicylic acid conventionally used as an electron accepting compound can be reduced by half, and only 4- (β-p-methoxyphenoxyethoxy) salicylic acid can be used. Compared with the heat-sensitive recording material used, the coating solution cost was 50% or less, which proved to be extremely economically advantageous. That is, the heat-sensitive recording material obtained in the examples of the present invention is excellent in color stability, sensitivity, and hardly causes fog even after forced storage,
Furthermore, it was found that the color image was excellent in chemical resistance such as PVC resistance, fluorescent pen resistance, and ink jet sheet resistance.

According to the heat-sensitive recording material of the present invention, excellent effects such as high stability of coloring density and excellent storage stability such as chemical resistance of an image area and a non-image area can be achieved.

 ────────────────────────────────────────────────── ─── Continuing 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 BB26 BB39 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 a phenol represented by the following general formula (1) is used as the electron-accepting compound. A thermosensitive recording material comprising a derivative and a salicylic acid derivative represented by the following general formula (2). Embedded image (Wherein, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, or a halogen atom, and R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, a halogen atom, or a hydroxy group. X represents a hydrogen atom, a hydroxy group, or an alkyl group.) (In the formula, R ⁵ represents an aryloxyalkyloxy 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 (3). Embedded image (Wherein, R ^6, R ⁷ each independently represent a hydrogen atom, an alkyl group or aryl group, further R ⁶ and R ⁷ may .R ⁸ also is bonded to each other to form a ring, R ⁹ are each Independently represents a hydrogen atom, an alkyl group or an aryl group.
R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group or a halogen atom. )