JPH08324131A - Thermal recording material - Google Patents

Abstract

PURPOSE: To prevent the yellowing of a background and to enhance light fastness, in a thermal recording material wherein a thermal recording layer containing an electron donating leuco dye and an electron acceptive compd. is provided on a support, by adding a polyvalent metal salt of a salicylic acid derivative and a specific benzotriazole ultraviolet absorber to the recording layer. CONSTITUTION: In a thermal recording material wherein a thermal recording layer containing an electron donating leuco dye and an electron acceptive compd. is provided on a support, a polyvalent metal salt of a salicylic acid derivative and a benzotriazole ultraviolet absorber represented by formula I (R<1> and R<2> may be same or different and is a 1-8C alkyl group) are added to the thermal recording layer. As the electron acceptive compd, the polyvalent metal salt of the salicylic acid derivative represented by formula II (R<3> is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or an aryloxy group, M is Zn, Ca or Al, m is an integer of 1-4 and n is an integer of 2 or 3) is added.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal recording material,
More specifically, the present invention relates to a heat-sensitive recording material containing a salicylic acid derivative polyvalent metal salt as an electron-accepting compound and a specific benzotriazole-based ultraviolet absorber, in which the background is not yellowed and an emulsion of the electron-accepting compound is stable.

[0002]

2. Description of the Related Art Recording materials using an electron-donating colorless dye and an electron-accepting compound are pressure-sensitive paper, thermal paper, photosensitive pressure-sensitive paper,
It is already well known as an electrically conductive recording paper and a thermal transfer paper. For example, British Patent 2,140,449, US Patents 4,480,052, 4,436,920, and Japanese Patent Publication No. 6
0-23992, JP-A-57-179836, 60-
123556, 60-123557 and so on.

As a recording material, in recent years, studies have been earnestly conducted to improve properties such as (1) color density and color sensitivity, and (2) fastness of a color body.

Particularly, the heat-sensitive recording material is disclosed in JP-B-43-416.
As detailed in No. 0, etc., these thermal recording systems have been applied to various fields such as facsimiles and printers, and their needs are expanding. Since these heat-sensitive recording materials have a primary color, the reaction between the electron-donating colorless dye and the electron-accepting compound occurs not only by heat but also by a solvent or the like, or the color formed by the thermal reaction causes discoloration. Had the drawback of.
In order to solve this, attempts have been made as disclosed in JP-B-51-43386, JP-A-53-17347, JP-A-56-72996, etc., but none of them have an effect of preventing fading. Or, although it is effective, it has a defect that color development (fog) occurs in a white background portion.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a heat-sensitive recording material excellent in light resistance, which is free from coloration or yellowing of the background, that is, white background, and further an emulsion of an electron-accepting compound in a heat-sensitive recording layer. An object of the present invention is to provide a heat-sensitive recording material which is excellent in product stability and can achieve good color development.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a salicylic acid derivative polyvalent metal salt and a specific benzotriazole-based ultraviolet absorber are contained, and that these dyes are encapsulated in microcapsules. As a result, they have found that the above object can be achieved, and completed the present invention.

That is, the heat-sensitive recording material of the present invention is a heat-sensitive recording material in which a heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support, and a salicylic acid derivative is contained in the heat-sensitive recording layer. Valvalent metal salt and the following general formula (1)
It is characterized by containing a benzotriazole type ultraviolet absorber represented by.

[0008]

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In the formula, R ¹ and R ² may be the same or different and each represents an alkyl group having 1 to 8 carbon atoms.

The heat-sensitive recording material of the present invention according to claim 2 is characterized in that the electron-accepting compound contains a salicylic acid derivative polyvalent metal salt represented by the following general formula (2).

[0011]

[Chemical 4]

In the formula, R ³ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or an aryloxy group, M represents Zn, Ca and Al, and m represents 1
Represents an integer of 4 and n represents an integer of 2 or 3.

The heat-sensitive recording material of the present invention according to claim 3 is
The electron-donating colorless dye is encapsulated in microcapsules.

The present invention will be described in detail below. In the heat-sensitive recording material of the present invention, it is particularly preferable to use the salicylic acid derivative polyvalent metal salt and the benzotriazole-based ultraviolet absorber represented by the general formula (1) as an emulsion. The method for preparing the emulsion is not particularly limited, and the emulsion can be prepared by a conventionally known method.

In the benzotriazole-based ultraviolet absorber represented by the general formula (1) used in the heat-sensitive recording material of the present invention, R ¹ and R ² may be the same or different, and each of them may have a hydrogen atom or a carbon number of 1 Each of the alkyl groups may have a straight chain structure or a branched structure. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, 2-methylbutyl group, n-pentyl group. , I-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group and the like. R ¹ and R ² are preferably a methyl group, an ethyl group, a tert-butyl group, a 2-ethylhexyl group, or the like, and it is preferable that the two are not simultaneously hydrogen atoms.

The benzotriazole type ultraviolet absorber represented by the general formula (1) contained in the heat-sensitive recording material of the present invention may be one kind or a mixture of two or more kinds.

Next, specific examples of the benzotriazole type ultraviolet absorber represented by the general formula (1) according to the present invention will be exemplified, but the present invention is not limited thereto.

[0018]

Embedded image

The salicylic acid derivative polyvalent metal salt contained in the heat-sensitive recording material of the present invention is not particularly limited, and those exemplified in JP-B-6-15292 can be preferably used. Among them, the salicylic acid derivative polyvalent metal salt represented by the general formula (2) is preferably used, and it has a function as an electron-accepting compound in the heat-sensitive recording material of the present invention.

In the general formula (2), R ³ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or an aryloxy group and has 1 to 18 carbon atoms.
A straight-chain or branched alkyl group having 4 to 1 carbon atoms
A cycloalkyl group having 2 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 1 to 18 carbon atoms
Preferred are an alkoxy group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, and an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms, and 7 carbon atoms. An aralkyl group having 12 and an aryl group having 6 to 12 carbon atoms are preferable. These are further alkyl groups having 1 to 8 carbon atoms, alkoxy groups having 1 to 8 carbon atoms, aryl groups having 6 to 10 carbon atoms, and 6 to 10 carbon atoms.
It may be substituted with an aryloxy group, a halogen atom or the like.

Specific examples of R ³ include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group,
i-butyl group, sec-butyl group, n-pentyl group, i
-Pentyl group, n-hexyl group, n-octyl group, 2-
Ethylhexyl group, n-decyl group, n-dodecyl group, cyclopentyl group, cyclohexyl group, benzyl group, 2-
Phenethyl group, 1-phenethyl group, phenyl group, p-tolyl group, p-methoxyphenyl group, p-chlorophenyl group, 2-methoxyethyl group, 2- (2-methoxyethoxy) ethyl group, 2-phenoxyethyl group , 2-phenoxypropyl group, 3-phenoxypropyl group and the like. m represents an integer of 1 to 4, where R ³ represents 1 to 4 functional groups added to the basic skeleton of salicylic acid,
m represents the number of functional groups to be added, and is preferably 1 or 2.

M represents Zn, Ca and Al, preferably Zn, n represents that the polyvalent metal is divalent or trivalent, and when M is Zn, n represents 2.

The salicylic acid derivative contained in the heat-sensitive recording material of the present invention preferably contains the salicylic acid derivative represented by the general formula (2), and may be contained alone or in combination of two or more. .

Next, specific examples of the salicylic acid derivative represented by the general formula (2) according to the present invention will be exemplified, but the present invention is not limited thereto.

[0025]

[Chemical 6]

The preferred addition amount of the salicylic acid derivative is 20 to 70% by weight of the electron-accepting compound.

Other electron-accepting compounds (developing agents) used in the heat-sensitive recording material of the present invention include phenol derivatives, salicylic acid derivatives other than those represented by the general formula (2), and metals of aromatic carboxylic acids. Examples thereof include salts, acid clay, bentonite, novolac resins, metal-treated novolac resins, and metal complexes.

Examples of these are JP-B-40-9309, JP-B-45-14039 and JP-A-52-140483.
JP-A-48-51510, JP-A-57-2108
86, JP-A-58-87089, and JP-A-59-11.
286, JP-A-60-176795, JP-A-61-176
No. 95988, etc.

This electron-accepting compound is, if necessary, used alone or in admixture and dispersed in a binder such as styrene-butadiene latex or polyvinyl alcohol, together with a pigment, paper, plastic sheet, resin coated paper, etc. A color developer sheet can be obtained by applying it to the support.

As the binder, it is preferable to use a carboxy-modified styrene-butadiene latex in combination with a water-soluble polymer from the viewpoint of light resistance and water resistance. Further, as the pigment, it is preferable to use calcium carbonate having an average particle diameter of 5.0 μm or less in an amount of 60% by weight or more based on all pigments from the viewpoint of color developing ability.

The electron-donating colorless dye used in the heat-sensitive recording material of the present invention is not particularly limited, and conventionally known triphenylmethanephthalide compounds, fluorane compounds, phenothiazine compounds, indolylphthalide compounds. Various dye compounds such as leuco auramine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds can be used. Specific examples of the phthalides include US Reissue Patent Specification No. 23,024.
U.S. Pat. No. 3,491,111, U.S. Pat.
491,112, 3,491,116 and 3,509,174, and specific examples of fluoranes are described in US Pat. Nos. 3,624,107 and 3,627,7.
No. 87, No. 3,641, 011, No. 3,462,
No. 828, No. 3,681,390, No. 3,92
No. 5,510, No. 3,959,571, specific examples of spirodipyrans are described in US Pat. No. 3,971,808.
, Pyridine-based and pyrazine-based compounds are described in US Pat. Nos. 3,775,424 and 3,853,869.
No. 4,246,318, and specific examples of fluorene compounds are described in JP-A-63-94878.

The coating amount of the electron-donating colorless dye according to the present invention is not particularly limited, but the total amount is 0.1 to 3.0 g / m 2.
² , particularly 1.0 to 2.5 g / m ² is preferable.

The electron-donating colorless dye is preferably contained in microcapsules and contained in the heat-sensitive recording layer from the viewpoint of stabilizing a printed image for a long period of time, that is, fading easily over time. .

Regarding the method for producing capsules, a method utilizing coacervation of a hydrophilic colloid sol described in US Pat. Nos. 2,800,457 and 2,800,458, and US Pat. No. 3,287,154. British patent 8
67,797, 950,443, 989,26
No. 4, No. 990,443, No. 1,091,076,
Japanese Examined Patent Publication No. 38-19574, No. 42-446, No. 42
Interfacial polymerization method described in US Pat.
Methods by precipitation of polymers described in U.S. Pat. No. 4,418,250 and U.S. Pat. No. 3,418,2.
A method using the isocyanate polyol wall material described in US Pat. No. 50, a method using the isocyanate wall material described in US Pat. No. 3,914,511, US Pat.
01,140, 4,087,376, 4,08
Urea-formaldehyde system described in No. 9,802,
Urea-formaldehyde-resorcinol-based wall material, melamine-formaldehyde resin, hydroxypropyl-pyrcellulose and other wall-forming materials, JP-B-36-9168 and JP-A-51-9079. -Situ method, British patent 9
52,807 and 965,074, the electrolytic dispersion cooling method, US Pat. No. 3,111,407, and British Patent 930,422 include the spray drying method. Although not limited thereto, it is preferable to form a polymer film as a microcapsule wall after emulsifying the core substance.

Generally, an electron-donating colorless dye is mixed with a solvent (synthetic oil such as alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated terphenyl, and chlorinated paraffin: vegetable oil such as cotton oil and castor oil). : Animal oil: Mineral oil or mixtures thereof)
Dissolve in the microcapsules contained in paper,
A color former sheet having a heat-sensitive recording layer is obtained by applying it to high-quality paper, plastic sheet, resin-coated paper, or the like.

In the heat-sensitive recording material of the present invention, the electron-donating colorless dye is an ultraviolet absorbing agent other than the conventionally known fluorescent whitening agent, antioxidant and benzotriazole type ultraviolet absorbing agent represented by the general formula (1). You may use together with an agent.

Preferred UV absorbers that can be used in combination are benzophenone UV absorbers, benzotriazole UV absorbers other than those represented by the general formula (1), salicylic acid UV absorbers, cyanoacrylate UV absorbers, Examples include oxalic acid anilide ultraviolet absorbers. Examples of these are JP-A-47-1053.
No. 7, No. 58-111942, No. 58-212844
59, 19945, 59-46646, 59-109055, 63-53544, 36-66466, 42-26187, 48-.
30492, 48-31255, 48-415
No. 72, No. 48-54965, No. 50-10726.
U.S. Pat. Nos. 2,719,086 and 3,707,3
No. 75, No. 3,754,919, No. 4,220,71
No. 1 and the like.

Preferred examples of the fluorescent whitening agent that can be used in combination include coumarin type fluorescent whitening agents. Examples of these are described in JP-B-45-4699 and JP-A-54-5324.

Preferred antioxidants that can be used in combination include hindered amine antioxidants, hindered phenol antioxidants, aniline antioxidants, quinoline antioxidants and the like. Examples of these are JP-A-59
-155090, 60-107383, 60-
107384, 61-1377770, 61-13.
No. 9481, 61-160287 and the like.

The amount of the ultraviolet absorber, fluorescent brightening agent, and antioxidant that can be used in combination is 0.05 to 1.0 g / m ² ,
Particularly, 0.1 to 0.4 g / m ² is preferable.

The weight ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably 1:10 to 1: 1 and more preferably 1: 5 to 2: 3.

When a heat-sensitive recording material is composed of the above-mentioned respective components, JP-A-62-144989 and JP-A-1-
It takes the form as described in the specification of 87291. Specifically, the electron-accepting compound dispersed together with the electron-donating colorless dye encapsulated in the capsule is
It is used by pulverizing and dispersing to a particle size of 0 μ or less, preferably 3 μ or less. The dispersion medium is generally 0.5 to 10
A water-soluble polymer aqueous solution having a concentration of about 10% is used, and dispersion is performed by a ball mill, a sand mill, a horizontal sand mill, an attritor,
It is performed using a colloidal mill or the like.

At this time, a thermofusible substance may be contained in the thermosensitive coloring layer in order to improve the thermal response. Typical examples of the heat-fusible substance include aromatic ethers, thioethers, esters and / or aliphatic amides or ureides.

Examples of these are disclosed in JP-A-58-57989,
58-87094, 61-58789, 62.
-109681, 62-2132674, 63-
151478, 63-235961, JP-A-2-
No. 184489 and No. 2-215585.

These are used at the same time as the electron-donating colorless dye or at the same time as being finely dispersed at the same time as the electron-accepting compound. 20% or more and 30% of the amount of these used and the electron-accepting compound
It is added in a weight ratio of 0% or less, especially 40% or more and 150%
The following are preferred.

Additives are added to the coating liquid thus obtained, if necessary, in order to meet various requirements. As an example of the additive, in order to prevent contamination of the recording head at the time of recording, an inorganic pigment, an oil absorbing substance such as polyurea filler is dispersed in a binder,
Furthermore, fatty acids, metal soaps, etc. are added to enhance the releasability of the head. Therefore, in general, in addition to electron-donating colorless dyes and electron-accepting compounds that directly contribute to color development, heat-fusible substances, pigments, waxes, antistatic agents, ultraviolet absorbers, defoamers, conductive agents, fluorescent dyes. An additive such as a surfactant is applied on the support to form a recording material. Further, if necessary, a protective layer may be provided on the surface of the heat-sensitive recording layer.

Usually, the electron-donating colorless dye and the electron-accepting compound are dispersed and applied in a binder. Water-soluble binders are generally used, and polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-anhydrous. Examples thereof include maleic salicylic acid copolymer, polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivative, casein, gelatin and the like. Further, a water-proofing agent may be added to these binders for the purpose of imparting water resistance, or an emulsion of a hydrophobic polymer, specifically, a styrene-butadiene rubber latex, an acrylic resin emulsion or the like may be added. The amount of these used is preferably 0.4 to 5 g / m ² , more preferably 0.8
˜1.6 g / m ² is preferred.

The obtained heat-sensitive coating liquid is applied to high-quality paper, high-quality paper having an undercoat layer, synthetic paper, plastic film and the like. At this time, it is particularly preferable from the viewpoint of dot reproducibility to use a support having a smoothness of 500 seconds or more, particularly 800 seconds or more as defined by JIS-8119.

In the heat-sensitive recording material of the present invention, various additives such as known waxes, antistatic agents, defoamers, conductive agents, fluorescent dyes, surfactants, ultraviolet absorber precursors, etc. are used as necessary. be able to.

In the heat-sensitive recording material of the present invention, a protective layer may be provided on the surface of the heat-sensitive recording layer, if necessary. Two or more protective layers may be laminated if 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, water-soluble polymer compounds such as sodium polystyrene sulfonate, sodium alginate, and styrene- Latex such as butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex and vinyl acetate emulsion are used. The water-soluble polymer compound in the protective layer can be crosslinked to further improve the storage stability, and a known crosslinking agent can be used as the crosslinking agent. Specifically N
Examples thereof include water-soluble initial condensates such as -methylol urea, N-methylol melamine, and urea-formalin; dialdehyde compounds such as glyoxal and glutaraldehyde; inorganic crosslinking agents such as boric acid and borax; and polyamide epichlorohydrin. Further, known pigments, metal soaps, waxes, surfactants and the like can be used in the protective layer. The coating amount of the protective layer is preferably 0.2 to 5 g / m ² ,
Furthermore, 0.5 to ² g / m ² is preferable. The film thickness is preferably 0.2 to 5 μm, and particularly preferably 0.5 to 2 μm.

When the protective layer is used in the heat-sensitive recording material of the present invention, the protective layer may contain a known ultraviolet absorber or ultraviolet absorber precursor.

As the support that can be used in the recording material of the present invention, acid paper, neutral paper, coated paper, plastic film laminated paper, synthetic paper, plastic film and the like can be used. Further, these supports may be provided with a known undercoat layer. This undercoat layer can be provided in the same manner as the protective layer.

In order to correct the curl balance of the support or to improve the chemical resistance from the back side, a back coat layer may be provided, and the back side may be combined with a release paper via an adhesive layer to label the label. You may take the form of. This back coat layer can be provided in the same manner as the protective layer.

[0054]

The present invention will be described below with reference to Examples.
The present invention is not limited to this. (Example 1) Preparation of developer (electron-accepting compound) emulsion dispersion (A) The compound represented by the formula (2-I), the following formula (E-
1), (E-2), (E-3), (E-4), (E-
The compound represented by 5) and the compound represented by the formula (1-I) are respectively 16.2 g, 10.4 g and 5.
8 g, 1.4 g, 2.2 g, 1.4 g and 4.2 g
A solution obtained by mixing 1.0 g of CP (oil manufactured by Daihachi Chemical Co., Ltd.) and 0.5 g of DEM (oil manufactured by Daihachi Chemical Co., Ltd.) and 20 g of ethyl acetate was heated and dissolved.

[0055]

[Chemical 7]

The resulting solution was added to polyvinyl alcohol 15
% Solution (PVA205C: manufactured by Kuraray Co., Ltd.) 25.0 g, polyvinyl alcohol 8% solution (PVA217C) 46.
0 g, sodium dodecyl sulfonate 0.5 g and water 7
Add 5.0 g to the mixed aqueous phase and use an ace homogenizer (trade name: Nippon Seiki Co., Ltd.) for 10000r.
The mixture was emulsified at pm for 3 minutes to obtain an emulsified dispersion liquid of an electron-accepting compound (hereinafter appropriately referred to as a developer) having an average particle diameter of 0.6 μm.

The average particle size is a 50% volume average particle size measured by using a laser diffraction particle size distribution measuring device (LA700: trade name, manufactured by Horiba Ltd.). Unless otherwise specified below, the average particle size represents the above 50% volume average particle size. (Example 2) Preparation of Developer Emulsion Dispersion (B) In the preparation of developer emulsion dispersion (A) described in Example 1, the compound represented by formula (1-I) (benzotriazole) is prepared. Type ultraviolet absorber) instead of the above formula (1-II)
A developer emulsified dispersion liquid (B) having an average particle size of 0.6 μm was obtained by the same method except that the compound represented by the same weight was used. (Comparative Example 1) Preparation of Developer Emulsion Dispersion Liquid (C) In the preparation of developer emulsion dispersion (A) described in Example 1, the following compound was used instead of the compound represented by Formula (1-I). A developer emulsified dispersion liquid having an average particle of 0.6 μm by the same method except that the compound (E-6) represented by the formula (benzotriazole-based ultraviolet absorber outside the scope of the present invention) was used in the same weight. (C) was obtained.

[0058]

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Comparative Example 2 Preparation of Developer Emulsion Dispersion Liquid (D) In the preparation of developer emulsion dispersion A described in Example 1, the compound represented by the formula (1-I) is used. By the same method except that the compound represented by the following formula (E-7) (benzotriazole-based ultraviolet absorber outside the scope of the present invention) was used in the same weight in place of the formula (E-7), the average particle size was 0.6 μm. An agent emulsion dispersion (D) was obtained.

[0060]

[Chemical 9]

Comparative Example 3 Preparation of Developer Emulsion Dispersion Liquid (E) In the preparation of the developer emulsion dispersion (A) described in Example 1, the compound represented by the formula (1-I) was used. A developer whose average particle size is 0.6 μm by the same method except that the compound represented by the following formula (E-8) (benzotriazole-based ultraviolet absorber outside the scope of the present invention) is used in the same weight instead. An emulsified dispersion (E) was obtained.

[0062]

[Chemical 10]

Comparative Example 4 Preparation of Developer Emulsion Dispersion (F) In the preparation of developer emulsion dispersion (A) described in Example 1, the formulas (2-I) and (E-1) were used. ), (E-2), (E
-3), compounds represented by (E-4) and (E-5), 16.2 g, 10.4 g, 5.8 g and 1.
For 4 g, 2.2 g and 1.4 g, the formula (E-
1), (E-2), (E-3), (E-4) and (E-
Compounds represented by 5), 18.3 g each, 1
A colorant emulsion dispersion (F) having an average particle diameter of 0.6 μm was obtained by the same method except that the amounts were changed to 0.1 g, 2.6 g, 3.8 g and 2.6 g. (Comparative Example 5) Preparation of Developer Emulsion Dispersion (G) In the preparation of developer emulsion (A) described in Example 1, Formulas (2-I), (E-1), ( E-2), (E
-3), compounds represented by (E-4) and (E-5), 16.2 g, 10.4 g, 5.8 g and 1.
For 4 g, 2.2 g and 1.4 g, the formula (E-
1), (E-2), (E-3), (E-4) and (E-
Compounds represented by 5), 18.3 g and 10.
1g, 2.6g, 3.8g and 2.6g, and the formula (1
-I) was used instead of the compound represented by the formula (1-II) in the same amount to obtain a color developer emulsion dispersion (G) having an average particle size of 0.6 μm. . (Comparative Example 6) Preparation of Developer Emulsion Dispersion (H) In the preparation of the developer emulsion dispersion (A) described in Example 1, the formulas (2-I), (E-1), ( E-2), (E
-3), compounds represented by (E-4) and (E-5), 16.2 g, 10.4 g, 5.8 g and 1.
For 4 g, 2.2 g and 1.4 g, the formula (E-
1), (E-2), (E-3), (E-4) and (E-
Compounds represented by 5), 18.3 g and 10.
1g, 2.6g, 3.8g and 2.6g, and the formula (1
In the same manner as above, except that the compound represented by formula (E-6) was used in the same weight in place of the compound represented by -I), a color developer emulsion (H) having an average particle diameter of 0.6 μm was obtained. . (Comparative Example 7) Preparation of Developer Emulsion Dispersion (I) In the preparation of developer emulsion (A) described in Example 1, Formulas (2-I), (E-1), ( E-2), (E
-3), compounds represented by (E-4) and (E-5), 16.2 g, 10.4 g, 5.8 g and 1.
4 g, 2.2 g and 1.4 g are replaced by the formula (E-1),
(E-2), (E-3), (E-4) and (E-5),
Each is 18.3 g, 10.1 g, 2.6 g, 3.8
g and 2.6 g, except that the compound represented by the formula (E-7) was used in the same weight in place of the compound represented by the formula (1-I), and a color having an average particle diameter of 0.6 μm was obtained by the same method. An agent emulsion dispersion (I) was obtained. Comparative Example 8 Preparation of Developer Emulsion Dispersion Liquid (J) In the preparation of the developer emulsion dispersion (A) described in Example 1, the formulas (2-I), (E-1), ( E-2), (E
-3), compounds represented by (E-4) and (E-5), 16.2 g, 10.4 g, 5.8 g and 1.
For 4 g, 2.2 g and 1.4 g, the formula (E-
1), (E-2), (E-3), (E-4) and (E-
5) 18.3 g, 10.1 g, 2.6 g, respectively
In the same manner as above, except that the compound represented by the formula (1-I) was replaced by the compound represented by the formula (1-I) and the same weight was used instead of the compound represented by the formula (1-I). A developer emulsion dispersion (J) was obtained. (Comparative Example 9) Preparation of developer emulsion dispersion (K) In the preparation of developer emulsion dispersion (A) described in Example 1, 4.2 g of the compound represented by the formula (1-I) was added. A developer emulsion dispersion having an average particle diameter of 0.6 μm was obtained by the same method except that the developer was removed. (Comparative Example 10) Preparation of developer emulsion dispersion (L) In the preparation of the developer emulsion dispersion (G) described in Comparative Example 5, 4.2 g of the compound represented by the formula (1-II) was added. A developer emulsified dispersion (L) having an average particle diameter of 0.6 μm was obtained by the same method except that it was removed. * Evaluation 1: Stability study of emulsion The obtained developer emulsion dispersion was left standing at room temperature after preparation of the emulsion, and 1 day later, the state of the solution was observed. The results are shown in Table 1 below.

[0064]

[Table 1]

The developer emulsified dispersion liquid in which precipitation had occurred could not provide a transparent heat-sensitive recording material described later, and the subsequent evaluation was terminated. The evaluations 2 and 3 described below were considered for the developer emulsion dispersions of Examples 1 and 2 and Comparative Examples 2 and 9 in which the emulsion could be stably present. * Evaluation 2: Evaluation of transmittance and visual observation On one surface of a transparent polyethylene terephthalate having a thickness of 75 μm, SBR latex is 0.3 g / solid weight.
m ² and then the following undercoat layer coating solution is applied such that the solid content weight per one side is 0.1 g / m ² to give a transparent support having an undercoat layer. Obtained. <Preparation of coating liquid for coating layer> 5% gelatin aqueous solution (# 81
0: trade name, manufactured by Nitta Gelatin Co., Ltd.) 200 g, gelatin dispersion 0.5 g in which 5% of polymethylmethacrylate resin particles having a particle diameter of 2 μm are dispersed, 1,2-benzothiazolin-3-one 3% aqueous solution 1. 0 g and di (2-ethyl) hexyl sulfonate 2% aqueous solution 10 g were mixed to obtain an undercoat layer coating solution. <Preparation of Sample> On the clear transparent support prepared by the above-mentioned method, the emulsion dispersion of the developer which did not cause precipitation in Evaluation 1 was applied so as to have a solid content of 5.0 g / m ² . (4 levels) Transmittance measurement of sample The transmittance spectrum of the obtained sample was measured with a spectrophotometer U.
-3400 (manufactured by Hitachi, Ltd.), wavelength 32
The measurement was performed in the area of 0 mm to 500 mm.

The obtained results are shown in FIG. Visual impression When the above four kinds of samples were observed through Sheacastin (manufactured by Seiko Co., Ltd.), Comparative Example 2 was clearly yellow, Examples 1 and 2 were slightly yellow, and Comparative Example 9 was not yellow. Evaluation 3: Examination of light resistance of heat-sensitive recording material Example 1 and 2 confirmed to exist stably in Evaluation 1.
A heat-sensitive recording material was actually prepared using the color developer emulsion dispersions of Comparative Examples 2 and 9. ◎ Thermal recording using the color developer emulsified dispersion (A) of Example 1
Preparation of Material <Preparation of Capsule Liquid Encapsulating Electron Donating Dye Precursor> Formulas (E-9), (E-10), (E-11), (E
-12), (E-13), (E-14) and (E-6).
Compounds represented by 9.8 g, 1.4 g, and 1.
9g, 3.0g, 1.0g, 0.4g and 0.4g,
After heat-dissolving in 20 g of ethyl acetate and gradually cooling to 40 ° C., 2.0 g of Takenate D110N (trade name: capsule wall agent manufactured by Takeda Yakuhin) and 11.6 g of Takenate D127N (same as above) and n-butanol. Add 4g,
The mixture was allowed to stir at 40 ° C for 40 minutes.

[0067]

[Chemical 11]

The resulting solution was treated with polyvinyl alcohol 8
% Solution (PVA217C: trade name of Kuraray Co., Ltd.)
After 40 g and 13 g of water were added to the mixed aqueous phase, the mixture was emulsified and dispersed at 10,000 μm for 5 minutes using an ace homogenizer.

After adding 70 g of water and 0.5 g of tetraethylenepentamine to the obtained emulsion, 60 ° C was added.
The encapsulation reaction was performed for 3 hours, and the average particle size was 0.
A 6 μm capsule liquid was obtained. <Preparation of protective layer coating liquid> Water 30 g, polyvinyl alcohol 6% aqueous solution (PVA124C: made by Kuraray) 20 g, dioctyl sulfosuccinate sodium salt 2% aqueous solution 0.3
g, kaolin dispersion (3 g of polyvinyl alcohol in 1 part of water
3.0 g of kaolin (35 g of kaolin dispersed in a pole mill) and 0.5 g of hydrin Z (trade name: manufactured by Chukyo Yushi Co., Ltd.) were mixed with the liquid mixed with 00 g to obtain a protective layer coating liquid. <Preparation of transparent support provided with undercoat layer> Transparent thickness 175
On one side of μm polyethylene terephthalate, SB
R latex was applied so as to have a solid content of 0.3 g / m ^2, and then the following undercoat layer coating solution was applied so that the solid content on one side was 0.1 g / m ^2. A transparent support provided with an undercoat layer was obtained. <Preparation of coating liquid for coating layer> 5% gelatin aqueous solution (# 81
0: Nitta Gelatin Co., Ltd.) 200 g, particle size 2 μm
0.5 g of 1,2-benzothiazoline-3, a gelatin dispersion containing 5% of polymethylmethacrylate resin particles
1.0 g of a 3% aqueous solution of 1-on and 10 g of a 2% aqueous solution of di (2-ethyl) hexyl sulfonate were mixed to obtain a coating solution for undercoat layer. <Preparation of coating liquid for heat-sensitive recording layer> 5.0 g of the capsule liquid (MC) already prepared, 15 g of the developer emulsion dispersion (A) (one day left after emulsification dispersion) and 10 g of water were mixed to obtain heat A coating liquid (1) for recording was obtained. <Preparation of Thermosensitive Recording Material> After coating the coating solution (1) for thermal recording on one surface of the transparent support provided with the undercoat layer so that the solid content is 14 g / m ² and drying it. Then, the prepared protective layer coating liquid was applied and dried so that the solid content was 2.5 g / m ^2, and the heat-sensitive recording material of the present invention was obtained. ◎ Thermal recording using the color developer emulsion dispersion (B) of Example 2
Preparation of Material In the preparation of a heat-sensitive recording material using the developer emulsified dispersion (A) of Example 1, a developer was used instead of the developer emulsified dispersion (A) when preparing a coating liquid for heat-sensitive recording. A thermosensitive recording material was obtained in the same manner except that the same weight of the emulsified dispersion liquid (B) was used. ◎ Thermal recording using the developer dispersion (D) of Comparative Example 2
Preparation of Material In the preparation of a heat-sensitive recording material using the developer emulsified dispersion (A) of Example 1, a developer was used instead of the developer emulsified dispersion (A) when preparing a coating liquid for heat-sensitive recording. A thermosensitive recording material was obtained by the same method except that the same weight of the emulsion dispersion (D) was used. ◎ Thermal recording using the developer emulsion dispersion (K) of Comparative Example 9
Preparation of Material In the preparation of a heat-sensitive recording material using the developer emulsified dispersion (A) of Example 1, a developer was used instead of the developer emulsified dispersion (A) when preparing a coating liquid for heat-sensitive recording. A thermosensitive recording material was obtained by the same method except that the same weight of the emulsified dispersion liquid (K) was used. * Weather resistance of the four types of heat-sensitive recording materials obtained by light resistance evaluation
It was irradiated with light for 24 hours in an o-meter (ATLAS (i65): trade name, manufactured by Toyo Seiki Co., Ltd.). At this time, the transmission density (Yellow value) of the material before and after the light irradiation was measured using TD904 (manufactured by Macbeth). The results are shown in Table 2 below.

[0070]

[Table 2]

The heat-sensitive recording materials using the color developer emulsified dispersions used in Examples 1 and 2 suppressed the yellow tint of the background of the material, and had very little yellowing after light irradiation for 24 hours. It can be seen that it is a color developer emulsion dispersion that contributes to the improvement of light resistance.

[0072]

The heat-sensitive recording material of the present invention does not cause coloring or yellowing of the background, that is, white background, is excellent in light resistance, and is excellent in stability of the electron-accepting compound emulsion, and achieves good color development. It showed an excellent effect of being able to do.

[Brief description of drawings]

FIG. 1 is a graph showing a transmittance spectrum of a sample obtained by applying a color developer emulsion dispersion on a transparent support.

Claims (3)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer comprising an electron-donating colorless dye and an electron-accepting compound, wherein the heat-sensitive recording layer comprises a salicylic acid derivative polyvalent metal salt and the following general formula: A heat-sensitive recording material comprising a benzotriazole-based ultraviolet absorber represented by (1). Embedded image In the formula, R ¹ and R ² may be the same or different and each represents an alkyl group having 1 to 8 carbon atoms. 2. The heat-sensitive recording material according to claim 1, wherein the electron-accepting compound contains a salicylic acid derivative polyvalent metal salt represented by the following general formula (2). Embedded image In the formula, R ³ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or an aryloxy group,
M represents Zn, Ca, and Al, m represents an integer of 1 to 4, and n represents an integer of 2 or 3. 3. The electron donating colorless dye is encapsulated in microcapsules.
The heat-sensitive recording material described.