JP3204826B2 - Thermal recording material - Google Patents

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 containing an electron-donating colorless dye and an electron-accepting compound having improved colorability, raw storability and stability of a color image. The present invention relates to a heat-sensitive recording material provided with a coloring layer formed on a support.

[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 an energized thermal recording paper, a thermal transfer paper, and the like. For example, British Patent Nos. 2,140,449, U.S. Patent Nos. 4,480,052 and 4,436,920
No., JP-B-60-23992, JP-A-57-1798
No. 36, No. 60-123556, No. 60-12355
No. 7 and more. In particular, the heat-sensitive recording material is disclosed in
No. 4160 and Japanese Patent Publication No. 45-14039. These thermal recording systems are applied to various fields such as facsimile machines, printers, labels, and the like, and needs are expanding. However, the heat-sensitive recording material has a drawback that fogging is caused by a solvent and the like, and a color-forming body is discolored and discolored by oils and fats, chemicals, etc., so that labels, slips, word processing paper, plotters and the like are used. In the field of paper and the like, the commercial value has been significantly impaired. The present inventors have determined that, for each of the electron-donating colorless dye and the electron-accepting compound, their oil solubility, solubility in water, partition coefficient, p
Focusing on Ka, the polarity of the substituent, and the position of the substituent, the development of good recording material and recording material has been pursued.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material having high sensitivity, good raw storability, and good printing quality with good stability of a color image.

[0004]

An object of the present invention is to provide a thermosensitive coloring layer containing a colorless electron-donating dye and an electron-accepting compound, and a protective layer containing a pigment and a binder as main components on a support. In the thermal recording material provided sequentially,
The heat-sensitive coloring layer contains a zinc salt of an N-substituted anthranilic acid derivative represented by the following general formula (I), and the protective layer
Was achieved by a heat-sensitive recording material containing an aluminum hydroxide pigment, wherein the dry coating amount of the protective layer was 0.5 to 5.0 g / m ² .

[0005]

Embedded image

[0006]

(In the above formula, R ₁ represents a hydrogen atom, an alkyl group or an aryl group, and R ₂ represents a phenyl group and a pheno group.
An alkyl group having a xy group as a substituent , an aryl group,
X represents an alkyloxy group or an aryloxy group, and X represents an oxygen atom or a sulfur atom. )

In the general formula (I), preferably, R ₁
Is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a monocyclic or fused ring aryl group having 6 to 10 carbon atoms,
R ₂ has a phenyl group and a phenoxy group as substituents
The alkyl group, a monocyclic or condensed aryl group having 6 to 10 carbon atoms, a substituted aryl group (substituent that, 1 carbon atoms
To 20 alkyl groups, hydroxyl groups, aryl groups, carboxyl groups, sulfo groups, sulfoamino groups, acylamino groups, and the like. ), An alkyloxy group having 1 to 20 carbon atoms, a substituted alkyloxy group (as the substituent, there are an aryl group, a carboxyl group, a sulfo group, a sulfoamino group, an acylamino group, etc.), and an aryloxy group having 1 to 20 carbon atoms. Group,
A substituted aryloxy group (substituents having 1 to 2 carbon atoms)
0 alkyl group, hydroxyl group, aryl group, carboxyl group, sulfo group, sulfoamino group, acylamino group and the like. ). Particularly preferably, R ₁ is a hydrogen atom, and R ₂ is a phenyl group or a phenoxy group as a substituent.
An alkyloxy group having 7 to 17 carbon atoms, an aralkyloxy group, an aryl group having 6 to 18 carbon atoms, and an alkyl-substituted aryl group.

Specific examples of the electron-accepting compound according to the present invention are shown below. ( 1 ) N- (dodecylphenylcarbamoyl)
Anthranilic acid,

( 2 ) N-benzoylanthranilic acid,
( 3 ) N- (4-chlorobenzoyl) anthranilic acid,
( 4 ) N- (4-methoxybenzoyl) anthranilic acid, ( 5 ) N- (2-methoxybenzoyl) anthranilic acid, ( 6 ) N- (2-methylthiobenzoyl) anthranilic acid, ( 7 ) N- (2- Chlorobenzoyl) anthranilic acid, ( 8 ) N- (phenoxyacetyl) anthranilic acid, ( 9 ) N- (4-methoxyphenoxyacetyl) anthranilic acid, ( 10 ) N- (phenylacetyl) anthranilic acid, ( 11 ) N- (Phenoxycarbonyl) anthranilic acid, ( 12 ) N- (benzyloxycarbonyl) anthranilic acid, ( 13 ) N- (2-phenoxypropionyl) anthranilic acid, ( 14 ) N-
(3-phenoxypropionyl) anthranilic acid, ( 1
5 ) N- (methoxyacetyl) anthranilic acid, ( 1
6 ) N- (methoxycarbonyl) anthranilic acid, ( 1
7 ) N- (ethoxycarbonyl) anthranilic acid, ( 1
8 ) N- (n-butyloxycarbonyl) anthranilic acid zinc salt , and the like. Among them, a zinc salt of N- (phenoxyacetyl) anthranilic acid is preferable.

The zinc salt of the N-substituted anthranilic acid derivative represented by the general formula (I) includes oxides, hydroxides, carbonates, such as zinc, aluminum, titanium, silicon, boron, magnesium and calcium; When used in combination with one or more carboxylate salts, image storability is further improved. Particularly among the metal compounds used in combination, zinc oxide, aluminum hydroxide,
Calcium carbonate, silicon dioxide, and aluminum silicate are preferred, and zinc oxide is particularly preferred.

According to the present invention, the dispersion particle size of the zinc salt of the N-substituted anthranilic acid derivative after being atomized by a sand mill or the like is preferably 3 μm or less, preferably 2 μm or less in order to obtain color development sensitivity. .

The zinc salt of the N-substituted anthranilic acid derivative according to the present invention may further include a salicylic acid derivative, a metal salt of an aromatic carboxylic acid, a phenol derivative,
An electron-accepting compound such as a phenol resin, a novolak resin, a metal-treated novolak resin, a metal complex, acidic clay, and bentonite may be used in combination. Examples of these are disclosed in JP-B-40-9309, JP-B-45-14039, JP-A-52-140483, JP-A-48-51510, JP-A-57-210886, and JP-A-58-87089.
JP-A-59-11286, JP-A-60-1767
No. 95, JP-A-61-95988 and the like.

Examples of some of these are 4-tert-butylphenol, 4-phenylphenol, 2,
2'-dihydroxybiphenyl, 2,2-bis (4-
Hydroxyphenyl) propane (bisphenol A),
4,4'-sec-butylidene diphenol, 4,4 '
-Cyclohexylidene diphenol, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-3 ', 4'dimethylphenylsulfone, 4-
(4-isopropoxyphenylsulfonyl) phenol, 4,4′-dihydroxydiphenyl sulfide,
1,4-bis- (4′-hydroxycumyl) benzene,
1,3-bis- (4′-hydroxycumyl) benzene,
4,4′-thiobis (6-tert-butyl-3-methylphenol), 4,4′-dihydroxydiphenylsulfone, 4-hydroxybenzoic acid benzyl ester,
3,5-di-tert-butylsalicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid,
-Cumyl-5-t-octylsalicylic acid, 3,5-di-
t-butylsalicylic acid, 3-phenyl-5-t-octylsalicylic acid, 3-methyl-5-α-methylbenzylsalicylic acid, 3-methyl-5-cumylsalicylic acid, 3,5
-Di-t-octylsalicylic acid, 3,5-bis (α-methylbenzyl) salicylic acid, 3-cumyl-5-phenylsalicylic acid, 5-n-octadecylsalicylic acid, 4-pentadecylsalicylic acid, 3,5-bis (α , Α-dimethylbenzyl) salicylic acid, 3,5-bis-t-octylsalicylic acid, 4-β-dodecyloxyethoxysalicylic acid, 4-methoxy-6-dodecyloxysalicylic acid, 4
-Β-phenoxyethoxysalicylic acid, 4-β-p-ethylphenoxyethoxysalicylic acid, 4-β-p-methoxyphenoxyethoxysalicylic acid, and the like, and metal salts thereof. The electron-accepting compound N- according to the present invention
The above electron accepting compound is preferably mixed with the substituted anthranilic acid derivative at a ratio of 10 to 100% by weight. Further, two or more of the above electron accepting compounds may be used in combination.

The electron-accepting compound is preferably used in an amount of 50 to 800% by weight, more preferably 100 to 500% by weight, based on the color of the electron-donating colorless dye.

The N-substituted anthranilic acid derivatives of the present invention
When a zinc salt is used, the chemical resistance of the white area and the image area is very good, but there is a problem that the white area discolors to light. Usually, even if a protective layer is provided on the thermosensitive coloring layer, the light resistance is not improved, but in this system, the reason is not clear, but it can be improved by providing a protective layer on the thermosensitive coloring layer. all right. In the present invention, aluminum hydroxide is used as the pigment , and the image storability is high.
If you write on the surface of the thermal paper with a pencil
In addition, the surface slips and the sensitivity hardly decreases.

The protective layer coating solution of the present invention is obtained by mixing a binder with a pigment dispersion. Further release agent if necessary,
Waterproofing agents, surfactants, waxes and the like may be added. The obtained protective layer coating liquid is applied and dried on the thermosensitive coloring layer using an apparatus such as a bar coater, an air knife coater, a blade coater, and a curtain coater to obtain a protective layer of the present invention. The protective layer may be applied simultaneously with the thermosensitive coloring layer, or may be applied after the thermosensitive coloring layer is dried after the thermosensitive coloring layer is applied. The dry coating amount of the protective layer is 0.5 to 5.0 g / m ² .
And preferably 0.8 to 3.0 g / m ² . When the coating amount is large, the thermal sensitivity is remarkably reduced, and when the coating amount is small, the protective effect is not sufficient. After the application of the protective layer, a calendering treatment may be performed as necessary.

Examples of the electron-donating colorless dye of the present invention include a triphenylmethanephthalide compound, a fluoran compound, a phenothiazine compound, an indolylphthalide compound, a leucouramine compound, a rhodamine lactam compound, There are various compounds such as a triphenylmethane-based compound, a triazene-based compound, a spiropyran-based compound, and a fluorene-based compound. 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 3,509,17
No. 4, specific examples of fluorans are described in US Pat.
No. 24,107, No. 3,627,787, No. 3,
Nos. 641,011, 3,462,828, 3,681,390, 3,920,510, 3,959,571, and specific examples of spirodipyrans are described in US Pat. No. 3,971,808, pyridine and pyrazine compounds are disclosed in U.S. Pat.
No. 5,424, No. 3,853,869, No. 4,2
No. 46,318, and specific examples of fluorene-based compounds are described in Japanese Patent Application No. 61-240989. Among them, black-colored 2-arylamino-3-H, halogen or alkyl-6-substituted aminofluorane is particularly effective.

As a specific example, for example, 2-anilino-3-
Methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-N-cyclohexyl-N-methylaminofluoran, 2-p-chloroanilino-3-methyl-6-dibutylaminofluoran, 2-anilino- 3-
Chloro-6-diethylaminofluoran, 2-anilino-3-methyl-6-N-ethyl-N-isoamylaminofluoran, 2-anilino-3-methyl-6-N-ethyl-N-dodecylaminofluoran, 2-o-chloroanilino-6-dibutylaminofluoran, 2-anilino-3-pentadecyl-6-diethylaminofluoran,
2-anilino-3-methyl-6-dibutylaminofluoran, 2-anilino-3-ethyl-6-dibutylaminofluoran, 2-m-toluidino-3-methyl-6-diisopropylaminofluoran, 2-anilino -3-Methyl-6-N-isobutyl-N-ethylaminofluoran, 2-anilino-3-methyl-6-N-ethyl-N-
Tetrahydrofurfurylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-isoamylaminofluoran, 2-anilino-3-methyl-6-N-methyl-N-γ-ethoxypropylaminofluor Oran, 2
-Anilino-3-methyl-6-N-ethyl-N-γ-ethoxypropylaminofluoran, 2-anilino-3-
Methyl-6-N-ethyl-N-γ-propoxypropylaminofluoran, 2-anilino-3-methyl-6-N
-Methyl-N-propylaminofluoran and the like.

A sensitizer may be added in addition to the electron-donating colorless dye and the electron-accepting compound. Examples of sensitizers include JP-A-58-57989, JP-A-58-87094,
Examples include compounds disclosed in JP-A-63-39375. Aromatic ethers (particularly benzyl ethers, di (substituted phenoxy) alkanes), aromatic esters and / or aliphatic amides, ureas or aromatic amides or ureas are representative. In particular, an aromatic ester is preferred, and a dibenzyl oxalate derivative is particularly preferred.

Next, a method for producing a typical thermosensitive coloring layer of the present invention will be described. Electron donating colorless dye, electron accepting compound,
The sensitizer is dispersed to several microns or less using a ball mill, a sand mill or the like together with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol. The sensitizer is an electron-donating colorless dye,
In addition to one or both of the electron accepting compounds, they may be dispersed at the same time, or in some cases, may be prepared in advance by preparing a eutectic with an electron donating colorless dye or an electron accepting compound. These dispersions are mixed after dispersion, and if necessary, a pigment, a surfactant, a binder, a metal soap, a wax,
An antioxidant, an ultraviolet absorber and the like are added to make a heat-sensitive coating liquid. The resulting heat-sensitive coating liquid is a high quality paper, a high quality paper having an undercoat layer,
After being applied and dried on synthetic paper, plastic film, etc.,
The calendering treatment imparts smoothness to the intended heat-sensitive recording material. In this case, it is particularly preferable to use a support having a smoothness specified by JIS-8119 of 500 seconds or more, particularly 800 seconds or more, from the viewpoint of dot reproducibility. In order to obtain a support having a smoothness of 500 seconds or more, (1) use a high-smoothness material such as synthetic paper or plastic film. (2) Provide an undercoat layer containing a pigment as a main component on the support. And (3) using a super calender to increase the smoothness of the support.

The binder used in the present invention includes:
Compounds that dissolve in water at 25 ° C. in an amount of 5% by weight or more are preferable, and specifically, polyvinyl alcohol (including modified polyvinyl alcohol such as carboxy-modified, acetoacetyl-modified, itaconic-acid-modified, maleic-acid-modified, and silica-modified). , Methylcellulose, carboxymethylcellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolysate, polyacrylamide, vinyl acetate-polyacrylic acid copolymer saponified product, etc. Is raised. These binders are used not only at the time of dispersion but also for the purpose of improving the strength of the coating film.
Latex binders of synthetic polymers such as butadiene copolymer, vinyl acetate copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, and polyvinylidene chloride can also be used in combination. If necessary, a crosslinking agent for an appropriate binder may be added according to the type of the binder.

Examples of the pigment used in the present invention include calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica, and amorphous silica.

As the metal soap used in the present invention, metal salts of higher fatty acids are used, such as zinc stearate, calcium stearate, and aluminum stearate.

Further, if necessary, a surfactant, an antistatic agent, an ultraviolet absorber, an antifoaming agent, a conductive agent, a fluorescent dye, a coloring dye and the like may be added. The applied heat-sensitive recording material is dried, subjected to a treatment such as a calender, and provided for use.

Further, if necessary, a back coat layer may be provided on the surface of the support of the thermosensitive recording material opposite to the thermosensitive coloring layer. As the back coat layer, any of those known as a back coat layer of a thermosensitive recording material can be used. Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[0027]

【Example】

Example 1 2-anilino-3-methyl-6-dibutylaminofluoran as an electron-donating colorless dye, zinc N-benzoylanthranilate as an electron accepting compound, and di (p-oxalate) as a sensitizer Methylbenzyl) ester was dispersed in a ball mill for 24 hours together with 100 g of a 5% aqueous solution of polyvinyl alcohol (Kuraray PVA-105) for 24 hours to obtain an average particle size of 1.5 μm or less to obtain each dispersion. In addition, 80 g of calcium carbonate was dispersed with a homogenizer together with 160 g of a 0.5% sodium hexametaphosphate solution to obtain a pigment dispersion. 5 g of an electron-donating colorless dye dispersion, 10 g of an electron-accepting compound dispersion, 10 g of di (p-methylbenzyl) oxalate dispersion, and 5 g of calcium carbonate dispersion were prepared as described above. , And 3 g of a 21% zinc stearate emulsion was added to obtain a heat-sensitive coating solution. This thermosensitive coloring layer coating solution is applied on a high-quality paper having a basis weight of 50 g / m ² by using a wire bar so that the dry weight of the coating layer is 5 g / m ² , and dried at 50 ° C. for 1 minute. I got Next, 80 g of aluminum hydroxide (Showa Denko Heidilite H42) was dispersed with a homogenizer together with 160 g of a 0.5% sodium hexametaphosphate solution, and 10% polyvinyl alcohol (Kuraray PVA-105) was added to the dispersion.
800 g of an aqueous solution and 100 g of a 21% zinc stearate emulsion were added to obtain a protective layer coating liquid. This protective layer coating solution was applied on the previously obtained thermosensitive coloring layer using a wire bar so that the dry weight of the protective layer was 2.0 g / m ² ,
After drying at 50 ° C. for 1 minute, a thermosensitive recording paper was obtained.

Example 2 The procedure of Example 1 was repeated, except that zinc N- (phenylacetyl) anthranilate was used instead of zinc N-benzoylanthranilate to prepare a heat-sensitive coating solution. Thermal recording paper was obtained in the same manner.

Example 3 The procedure of Example 1 was repeated except that zinc N- (benzyloxycarbonyl) anthranilate was used instead of zinc N-benzoylanthranilate to prepare a heat-sensitive coating solution. Obtained a thermosensitive recording paper by the same method.

Example 4 A heat-sensitive coating solution was prepared in the same manner as in Example 1, except that zinc N- (2-phenoxypropionyl) anthranilate was used instead of zinc zinc N-benzoylanthranilate. Except for the above, a thermosensitive recording paper was obtained in the same manner.

Example 5 The procedure of Example 1 was repeated, except that zinc N- (phenoxyacetyl) anthranilate was used instead of zinc zinc N-benzoylanthranilate to prepare a heat-sensitive coating solution. Thermal recording paper was obtained in the same manner.

Example 6 The procedure of Example 1 was repeated except that a heat-sensitive coating solution was prepared using N- (phenoxyacetyl) anthranilic acid instead of using zinc N-benzoylanthranilate. The heat-sensitive recording paper was obtained by the method described above.

Example 7 In the preparation of Example 1, N- (phenoxyacetyl) anthranilic acid was used in place of zinc N-benzoylanthranilate, and 80 g of zinc oxide was added to sodium hexametaphosphate. A thermosensitive recording paper was obtained in the same manner except that 1 g of a dispersion liquid dispersed with a homogenizer was added together with 160 g of a 0.5% solution to prepare a thermosensitive coating liquid.

Example 8 The same procedure as in Example 7 was repeated except that a heat-sensitive coating solution was prepared using 60 g of aluminum hydroxide + 20 g of kaolin (Shiroishi Kogyo Kaobrite) instead of using 80 g of aluminum hydroxide. Thermal recording paper was obtained by the method.

Example 9 A thermosensitive recording paper was prepared in the same manner as in Example 7, except that a heat-sensitive coating solution was prepared using 40 g of aluminum hydroxide and 40 g of kaolin instead of using 80 g of aluminum hydroxide. Obtained.

Example 10 Instead of using 80 g of aluminum hydroxide of Example 7, aluminum hydroxide 60 g + calcium carbonate (Shiroishi Kogyo Unibur7) was used.
0) A heat-sensitive recording paper was obtained in the same manner except that a heat-sensitive coating solution was prepared using 20 g.

Comparative Example 1 A heat-sensitive recording paper was obtained in the same manner as in Example 1, except that bisphenol A was used instead of zinc N-benzoylanthranilate to prepare a heat-sensitive coating solution. .

Comparative Example 2 A heat-sensitive coating was prepared in the same manner as in Example 1, except that a benzyl 4-hydroxybenzoate was used to prepare a heat-sensitive coating solution instead of using zinc N-benzoylanthranilate. Recording paper was obtained.

(Comparative Example 3) Instead of using the zinc N-benzoylanthranilate of Example 1, 4- (4-
A heat-sensitive recording paper was obtained in the same manner except that a heat-sensitive coating solution was prepared using isopropoxyphenylsulfonyl) phenol.

Comparative Example 4 A heat-sensitive recording paper was obtained in the same manner as in Example 7 except that no protective layer was provided.

The heat-sensitive recording paper obtained as described above is
The surface was treated with a calender, and the smoothness was adjusted to a Beck smoothness of 300 ± 50 seconds to obtain a heat-sensitive recording material. The evaluation of the thermal recording paper was performed as follows. (1) Color density is 30 mJ / printing energy using a Kyocera printing tester.
It was printed in mm ² and the color density was measured with a Macbeth densitometer.
The higher the value, the higher the sensitivity of the thermal recording paper. (2)
In the chemical resistance test, a Mylar tape (manufactured by Nitto Denko) was adhered to the coloring surface of the recording paper obtained by the above method, and the degree of fog on a white background portion and decoloration (fading) of the coloring portion were evaluated. (3) In the light fastness test, the white paper density (Yellow density) and the image density after irradiating the recording paper obtained by the above method with a fluorescent lamp tester for 5000 lux for 100 hours were measured. Table 1 shows the above results.

[0042]

[Table 1]

[0043]

As can be seen from the results shown in Table 1, the recording material of the present invention has high sensitivity, does not cause fogging or decoloration of the colored portion due to chemicals, and has extremely high light resistance in the white background portion and the image portion. It turns out that it has excellent performance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-111905 (JP, A) JP-A-5-318928 (JP, A) JP-A-3-169587 (JP, A) JP-A-3-3 227294 (JP, A) JP-A-62-59081 (JP, A) JP-A-6-155925 (JP, A) JP-A-6-270549 (JP, A) JP-A-6-64321 (JP, A) JP-A-5-169832 (JP, A) JP-A-5-176552 (JP, A) JP-A-7-109423 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (1)

(57) [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, and a protective layer containing a pigment and a binder as main components. containing zinc salt of N--substituted anthranilic acid derivative represented by the following formula (I), and the coercive
Mamoruso contains pigment aluminum hydroxide, heat-sensitive recording material dry coating amount of the protective layer is characterized by a 0.5 to 5.0 g / m ^2. Embedded image (In the above formula, R ₁ represents a hydrogen atom, an alkyl group or an aryl group, and R ₂ represents a phenyl group and a phenoxy group.
X represents an oxygen atom or a sulfur atom having an alkyl group, an aryl group, an alkyloxy group, or an aryloxy group. )