JP2003237245A - Heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material showing the compatibility between excellent image conservation properties at a bright spot and reduction of a light-exposed texture coloring. <P>SOLUTION: In the heat-sensitive recording material having at least a single heat-sensitive recording material formed on a support, at least a single heat- sensitive recording layer contains at least one kind of an electron-receptive compound represented by formula (1) (wherein R<SP>1</SP>and R<SP>2</SP>are each independently a hydrogen atom or an alkyl group. R<SP>11</SP>to R<SP>14</SP>are each independently a hydrogen atom or an alkyl group). Together with an electron-donative colorless dye and the electron-donative colorless dye is encapsulated by a microcapsule. <P>COPYRIGHT: (C)2003,JPO

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 which has both good image storability in a bright place and reduction of exposed background coloration.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is relatively inexpensive, and its recording equipment is compact and maintenance-free, and thus is widely used.
Under such circumstances, recently, sales competition of heat-sensitive recording materials has intensified, and heat-sensitive recording materials are required to have higher functions that are different from conventional functions. To meet this demand,
Research has been earnestly conducted on color density, image storability, head matching property, and the like of thermosensitive recording materials.

In a conventional heat-sensitive recording material, 2,2-bis (4-hydroxyphenyl) propane (so-called "bisphenol A") is used as an electron-accepting compound that reacts with an electron-donating colorless dye to form a color in the colorless paint. ) Is widely used. However, none of these heat-sensitive recording materials has been able to simultaneously satisfy each of sensitivity, background covering, image storability, chemical resistance, and head matching (sticking) property.

Further, Japanese Patent Publication No. 20792/1992 discloses that
A recording material using N-substituted sulfamoylphenol or N-substituted sulfamoylnaphthol as an electron-accepting compound is described. This recording material (pressure-sensitive, heat-sensitive) has improved image density, image stability, cost and the like. However, there is room for further improvement in image storability.

Further, the conventional heat-sensitive recording material has a drawback that it is colored by the generation of light stain when the background is exposed to light.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above problems, and provides a heat-sensitive recording material having both good image storability in a bright place and reduction of exposed background coloration. The task is to do

[0007]

The present inventors have conducted extensive studies on electron-accepting compounds, pursued the development of excellent thermal recording materials, and completed the present invention. That is, the present invention relates to <1> a thermosensitive recording material in which at least one thermosensitive recording layer is provided on a support, at least one of the thermosensitive recording layers together with an electron-donating colorless dye is represented by the following general formula ( A heat-sensitive recording material comprising at least one electron-accepting compound represented by 1) and containing the electron-donating colorless dye in microcapsules.

[0008]

[Chemical 3]

(In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group. R ^{11 to} R ¹⁴
Each independently represent a hydrogen atom or an alkyl group. )

<2> The heat-sensitive material according to <1>, wherein the electron-accepting compound represented by the general formula (1) is an electron-accepting compound represented by the following general formula (2). It is a recording material.

[0011]

[Chemical 4]

(In the general formula (2), R ³ represents an alkyl group.)

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-sensitive recording material of the present invention, at least one heat-sensitive recording layer is provided on a support, and at least one of the heat-sensitive recording layers together with the electron-donating colorless dye described above is used. At least one electron-accepting compound represented by the general formula (1) is contained. The thermal recording material of the present invention will be described below.

(Heat-sensitive recording layer) At least one layer of the heat-sensitive recording layer in the present invention contains at least one electron-accepting compound represented by the general formula (1) together with an electron-donating colorless dye. It is a layer and may be provided with another heat-sensitive recording layer. The thermal recording layer in the invention will be described below.

The electron-donating colorless dye is not particularly limited and may be appropriately selected from known ones according to the purpose. In the present invention, an electron-donating colorless dye precursor may be used. .

As the electron-donating colorless dye precursor,
For example, triarylmethane compounds, diphenylmethane compounds, thiazine compounds, xanthene compounds,
Examples include spiropyran compounds. They are,
One kind may be used alone, or two or more kinds may be used in combination. Among these, a triarylmethane compound and a xanthene compound are preferable from the viewpoint of high color density and usefulness. Examples of these are 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (ie, crystal violet lactone), 3,3-bis (p
-Dimethylamino) phthalide, 3- (p-dimethylaminophenyl) -3- (1,3-dimethylindole-3)
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (o-methyl-p-diethylaminophenyl)
-3- (2-methylindol-3-yl) phthalide,
4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenyl leuco auramine, N
-2,4,5-trichlorophenyl leuco auramine,
Rhodamine-B-anilinolactam, Rhodamine (p-
Nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam,

2-benzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethyl Aminofluorane, 2-anilino-3-methyl-6-isoamylethylaminofluorane, 2-
(O-chloroanilino) -6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-2-diethylaminofluorane, 2-anilino-3-chloro-6
-Diethylaminofluorane, benzoyl leuco methylene blue, p-nitrobenzyl leuco methylene blue,
3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-
Dinaphthopyran, 3-benzylspirodinaphthopyran,
3-propyl-spiro-dibenzopyran, and the like.

The coating amount of the electron-donating colorless dye is not particularly limited, but is 0.01-2.0 g / m 2 in terms of solid content coating amount.
² is preferable, and 0.1 to 0.6 g / m ² is more preferable.

(Electron-Accepting Compound) At least one layer of the heat-sensitive recording layer in the invention contains at least one electron-accepting compound represented by the following general formula (1). Less than,
The electron-accepting compound will be described.

[0020]

[Chemical 5]

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group. General formula (1)
In the above, the alkyl group represented by R ¹ and R ² is preferably an alkyl group having 1 to 12 carbon atoms from the viewpoint of color developability,
An alkyl group having 6 carbon atoms is more preferable, and an alkyl group having 1 to 4 carbon atoms is further preferable.

In the general formula (1), R ^{11 to} R ¹⁴ each independently represent a hydrogen atom or an alkyl group. R ^{11 to} R ¹⁴
The alkyl group represented by may be linear or branched, is preferably an alkyl group having 1 to 20 carbon atoms, and has 1 carbon atom.
The alkyl group having 10 to 10 is more preferable, and the alkyl group having 1 to 4 carbons is further preferable.

The electron-accepting compound represented by the general formula (1) is preferably an electron-accepting compound represented by the following general formula (2).

[0024]

[Chemical 6]

In the general formula (2), R ³ represents an alkyl group. The alkyl group represented by R ³ is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and further preferably an alkyl group having 1 to 4 carbon atoms, from the viewpoint of color development.

Specific examples of the electron-accepting compound represented by the general formula (1) in the present invention will be given below, but the present invention is not limited thereto.

[0027]

[Table 1]

In the heat-sensitive recording material of the present invention, in addition to the electron-accepting compound represented by the general formula (1), a conventionally known electron-accepting compound is used in combination as long as the effect of the present invention is not impaired. You may. Examples of the known electron-accepting compound include a phenol derivative, a salicylic acid derivative, and a hydroxybenzoic acid ester.
Among these, bisphenols and hydroxybenzoic acid esters are particularly preferable, and specifically, 2,2-bis (p-hydroxyphenyl) propane (that is, bisphenol A) and 4,4 ′-(p-phenylenediene). Isopropylidene) diphenol (ie, bisphenol P),
2,2-bis (p-hydroxyphenyl) pentane,
2,2-bis (p-hydroxyphenyl) ethane, 2,
2-bis (p-hydroxyphenyl) butane, 2,2-
Bis (4'-hydroxy-3 ', 5'-dichlorophenyl) propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) propane, 1,1- (p-hydroxyphenyl) ) Pentane, 1,1- (p-hydroxyphenyl) -2-ethylhexane, 3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (tert-butyl) salicylic acid and Its polyvalent metal salt, 3-α, α-dimethylbenzyl salicylic acid and its polyvalent metal salt, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p
-Phenylphenol, p-cumylphenol and the like are particularly preferable.

The coating amount of the electron-accepting compound represented by the general formula (1) is not particularly limited, but the coating amount of solid content is preferably 0.5 to 10.0 g / m ² , and 1.0 to 5. 0
g / m ² is more preferable.

When the heat-sensitive recording material of the present invention has a plurality of heat-sensitive recording layers, it is necessary to use color formers having different energies required for color development. The heat-sensitive recording material of the present invention may be full-color or mono-color, but other than the heat-sensitive recording layer containing the electron-donating colorless dye and the electron-accepting compound represented by the general formula (1). To
It is desirable to have at least one heat-sensitive recording layer (light-fixing type heat-sensitive recording layer) containing a diazonium salt compound, a diazo-based color former containing a coupler that undergoes a coupling reaction with the diazonium salt compound, and a binder as main components. In addition to the above-mentioned diazo-based color formers, the color-forming agent for the heat-sensitive recording layer is a base color-forming system, a chelate color-developing system, which develops a color upon contact with a basic compound, or a decolorization reaction by reacting with a nucleophile. It may be any color-developing system or the like.

When the heat-sensitive recording layer contains the diazonium salt compound and a coupler which reacts with the diazonium salt compound to produce a color when heated, the heat-sensitive recording layer contains the diazonium salt compound and the coupler. A basic substance or the like that accelerates the color forming reaction is preferably added.

The diazonium salt compound is a compound represented by the following general formula (B), and the maximum absorption wavelength thereof can be controlled by the position and kind of the substituent of the Ar moiety. Formula _{(B): Ar-N 2} + X - In the general formula (B), Ar represents an aryl group. X ⁻ represents an acid anion.

Specific examples of the diazonium salt compound include 4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4-dioctylaminobenzenediazonium, 4
-(N- (2-ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium, 4-N-ethyl-N-
Hexadecylamino-2-ethoxybenzodiazonium, 3-chloro-4-dioctylamino-2-octyloxyobenzenediazonium, 2,5-dibutoxy-
4-morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-
Dibutoxy-4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzene Diazonium, 2,5-dibutoxy-4-tolylthiobenzenediazonium, 3- (2-octyloxyethoxy) -4-
Examples thereof include acid anion salts such as morpholinobenzenediazonium and the following diazonium salt compounds (D-1 to 5). These may be used alone or in combination of two or more. Among these, hexafluorophosphate salts, tetrafluoroborate salts, 1,5-
Naphthalene sulfonate salts are particularly preferred.

[0034]

[Chemical 7]

Among these diazonium salt compounds,
Photodecomposes by light with a wavelength of 300 to 400 nm, 4-
(N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4
-Dioctylaminobenzenediazonium, 4- (N-
(2-Ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium, 4-N-ethyl-N-hexadecylamino-2-ethoxybenzodiazonium, 2,5
-Dibutoxy-4- (N- (2-ethylhexanoyl))
Piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, diazonium salts shown in the specific examples D-3 to 5 Compounds are particularly preferred. The maximum absorption wavelength of the diazonium salt compound here is measured by a spectrophotometer (Shimazu MPS-2000) prepared by coating each diazonium compound at a coating amount of 0.1 to 1.0 g / m ^2. It was done.

Examples of couplers that develop color upon reaction with the diazonium salt compound when they are heated include resorcin, flurglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, and 1-hydroxy-2-naphthoic acid morpholinopropylamide. 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-
Naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyloxypurupyramide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, Benzoylacetanilide, 2-chloro-5-octylacetoacetanilide,
1-phenyl-3-methyl-5-pyrazolone, 1-
(2'-octylphenyl) -3-methyl-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl)
-3-benzamido-5-pyrazolone, 1- (2 ',
4 ', 6'-trichlorophenyl) -3-anilino-5
-Pyralone, 1-phenyl-3-phenylacetamido-5-pyrazolone, compounds shown in the following (C-1 to 6),
And so on. These couplers may be used alone or in combination of two or more.

[0037]

[Chemical 8]

[0038]

[Chemical 9]

The basic substance is not particularly limited and may be appropriately selected from known ones according to the purpose. In addition to inorganic or organic basic compounds, alkaline substances that cause decomposition or the like when heated are used. Releasing compounds are also included, and typical examples thereof include organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, and indoles. , Imidazoles, imidazolines, triazoles, morpholines,
Examples thereof include nitrogen-containing compounds such as piperidines, amidines, formazines and pyridines.

Specific examples of these include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allylurea, thiourea,
Methylthiourea, allylthiourea, ethylenethiourea,
2-benzylimidazole, 4-phenylimidazole, 2-phenyl-4-methylimidazole, 2-undecylimidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-
2-imidazoline, 2-phenyl-2-imidazoline,
1,2,3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetate, N, N '
-Dibenzylpiperazine, 4,4'-dithiomorpholine, morpholinium trichloroacetate, 2-aminobenzothiazole, 2-benzoylhydrazinobenzothiazole and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the binder that can be used in the heat-sensitive recording layer include known water-soluble polymer compounds and latexes. The water-soluble polymer compound, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivative, casein, acacia, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, polyvinyl alcohol, Examples include epichlorohydrin-modified polyamide, isobutylene-maleic salicylic acid copolymer, polyacrylic acid, polyacrylic acid amide and modified products thereof, and the like, and the latexes include styrene-butadiene rubber latex and methyl acrylate-butadiene. Examples thereof include rubber latex and vinyl acetate emulsion.

Further, for the purpose of improving the fastness of the color image to light and heat or reducing the yellowing of the unprinted part (non-image part) after fixing due to light, the following known antioxidants, etc. It is also preferable to use. Examples of the antioxidant include those disclosed in European Published Patent No. 223739.
No. 309401, No. 309402, No. 309402, No. 310551, No. 310552, No. 459416, and German Published Patent No. 343.
5443, JP-A-54-48535, 6
No. 2-262047, No. 63-113536, No. 63-163351, and JP-A-2-2626.
54, JP-A-2-71262, JP-A-3-
No. 121449, JP-A-5-61166, JP-A-5-119449, and US Pat. No. 4,814,426.
2, those described in U.S. Pat. No. 4,980,275 and the like can be mentioned.

The electron-donating colorless dye of the present invention is used by being encapsulated in microcapsules. If the electron-donating colorless dye is not encapsulated in microcapsules but dispersed in the heat-sensitive recording layer, image storability is deteriorated.

As a method of encapsulating the electron-donating colorless dye in microcapsules, a conventionally known method can be used. For example, the electron-donating colorless dye precursor and the microcapsule wall precursor are dissolved in a poorly water-soluble or insoluble organic solvent, added to an aqueous solution of a water-soluble polymer, and emulsified and dispersed using a homogenizer or the like. Then, the electron donating colorless dye can be prepared by raising the temperature to form a wall film at the oil / water interface of the polymer substance which becomes the microcapsule wall.

Specific examples of the microcapsule wall film include, for example, polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin, styrene-acrylate copolymer resin, and styrene. Examples of the wall film include an ethylene-methacrylate copolymer resin, gelatin, polyvinyl alcohol, and the like. Among these, a wall film made of polyurethane / polyurea resin is preferable.

The microcapsules having a wall film made of the polyurethane-polyurea resin are prepared by mixing a microcapsule wall precursor such as polyvalent isocyanate with a core substance to be encapsulated in the microcapsules, and dissolving it in water-soluble polyvinyl alcohol or the like. It is manufactured by emulsifying and dispersing in an aqueous solution of a polymer and raising the liquid temperature to cause a polymer forming reaction at the interface of oil droplets.

Specific examples of the polyvalent isocyanate compound include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate and diphenylmethane-. 4,
4'-diisocyanate, 3,3'-diphenylmethane-4,4'-diisocyanate, xylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2- Diisocyanates such as diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4 ′, 4′-triphenylmethanetriisocyanate, toluene-2, Triisocyanates such as 4,6-triisocyanate, tetraisocyanates such as 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate, hexamethylene diisocyanate and trimethylol Adducts with propane,
An isocyanate prepolymer such as an adduct of 2,4-tolylene diisocyanate and trimethylolpropane, an adduct of xylylene diisocyanate and trimethylolpropane, an adduct of tolylene diisocyanate and hexanetriol, and the like can be given. These may be used alone or in combination of two or more, and among these, those having three or more isocyanate groups in the molecule are particularly preferable.

In the method of encapsulating the electron-donating colorless dye in microcapsules, the organic solvent in which the electron-donating colorless dye is dissolved may be a solid at room temperature, a liquid, or a polymer. A low boiling auxiliary solvent such as acetic acid ester, methylene chloride, cyclohexanone and / or phosphoric acid ester, phthalic acid ester, acrylic acid ester, methacrylic acid ester,
Other examples include carboxylic acid ethesul, fatty acid amide, alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, chlorinated paraffin, alcohol-based, phenol-based, ether-based, monoolefin-based, and epoxy-based. As a specific example,
Tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilaurate phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol benzoate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, tri Trioctyl meritate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isoamyl biphenyl, chlorinated paraffin, diisopropyl naphthalene, 1,1′-ditolylethane, 2,4-diter-shalyamylphenol, N, N-dibutyl- 2-butoxy
Examples thereof include 5-tert-aryoctylaniline, hydroxybenzoic acid 2-ethylhexyl ester, and high-boiling oils such as polyethylene glycol. These may be used alone or in combination of two or more,
Among these, alcohol type, phosphoric acid ester type, carboxylic acid type ester type, alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, and diarylethane are preferable.

As the water-soluble polymer for dispersing the oil phase of the microcapsules in the aqueous phase, polyvinyl alcohol, silanol modified polyvinyl alcohol, carboxy modified polyvinyl alcohol, amino modified polyvinyl alcohol, itaconic acid modified polyvinyl alcohol are used. ,
Styrene-maleic anhydride copolymer, butadiene maleic anhydride copolymer, ethylene maleic anhydride copolymer,
Examples thereof include isobutylene maleic anhydride copolymer, polyacrylamide, polystyrene sulfonic acid, polyvinylpyrrolidone, ethylene-acrylic acid copolymer and gelatin. The average particle size of the microcapsules,
0.1 to 5.0 μm is preferable, and 0.2 to 2.0 μm is more preferable.

In the heat-sensitive recording layer of the present invention, the mode of containing the electron-accepting compound, the diazonium salt compound, the coupler, the basic substance, etc. is not particularly limited and may be appropriately selected according to the purpose. Can
For example, (1) a solid dispersion method, (2) an emulsification dispersion method, (3) a polymer dispersion method, (4) a latex dispersion method, and (5) microcapsules. And the like.

Of these, from the viewpoint of storage stability, the method of encapsulating in a microcapsule and containing it in the heat-sensitive recording layer is preferable, and in the case of utilizing the color reaction of the diazonium salt compound and the coupler, the diazonium is used. A method in which a salt compound is encapsulated in microcapsules and contained in the thermosensitive recording layer is preferable. The method of encapsulating the diazonium salt compound or the like in the microcapsules is the same as the method of encapsulating the electron-donating colorless dye in the microcapsules.

When the thermosensitive recording layer of the present invention has a multilayer structure, a multicolor thermosensitive recording material can be obtained by changing the hue of each thermosensitive recording layer. The layer structure in this case is not particularly limited and can be appropriately selected according to the purpose.
2 layers of heat-sensitive recording layers in which two kinds of diazonium salt compounds are combined with couplers that react with each diazonium salt compound to develop different hues, and an electron-donating colorless dye and an electron-accepting compound are combined. It is preferable that the heat-sensitive recording layer and the multi-color heat-sensitive recording layer are laminated.
That is, a thermosensitive recording layer A containing an electron-donating colorless dye and an electron-accepting compound on a support described later, having a maximum absorption wavelength of 3
Heat-sensitive recording layer B-1 containing a diazonium salt compound having a wavelength of 60 ± 20 nm and a coupler that reacts with the diazonium salt compound to produce a color, and the maximum absorption wavelength is 400 ± 20.
A multicolor heat-sensitive recording material in which a heat-sensitive recording layer B-2 containing a diazonium salt compound having a thickness of nm and a coupler that reacts with the diazonium salt compound to produce a color when heated is laminated in this order is preferable.

As a recording method of this multicolor heat-sensitive recording material, first, the heat-sensitive recording layer B-2 is heated and then the heat-sensitive recording layer B-
The diazonium salt compound contained in 2 and the coupler are colored. Next, after irradiating with light of 400 ± 20 nm to decompose the unreacted diazonium salt compound contained in the heat-sensitive recording layer B-2, sufficient heat is developed for the heat-sensitive recording layer B-1 to develop color. In addition, the diazonium salt compound and the coupler contained in the thermosensitive recording layer B-1 are allowed to develop color. At this time, the heat-sensitive recording layer B-2 is also strongly heated at the same time, but since the diazonium salt compound has already been decomposed and the color forming ability has been lost, no color is formed. Further, the diazonium salt compound contained in the thermosensitive recording layer B-1 is decomposed by irradiating with light of 360 ± 20 nm, and finally, sufficient heat for the thermosensitive recording layer A to develop color is applied to develop the color. At this time, the thermal recording layer B-
2 and the heat-sensitive recording layer B-1 are also heated strongly at the same time, but the diazonium salt compound is already decomposed and the color forming ability is lost, so that no color is formed.

In the case of the above multicolor heat-sensitive recording layer,
If the coloring hue of each heat-sensitive recording layer is selected to be the three primary colors in subtractive color mixing, yellow, magenta, and cyan,
Full-color image recording is possible.

The heat-sensitive recording material of the present invention preferably has a single or a plurality of heat-sensitive recording layers on the support, as well as a light transmittance adjusting layer, a protective layer and an intermediate layer.

(Light Transmittance Adjusting Layer) The light transmittance adjusting layer contains an ultraviolet absorber precursor and does not function as an ultraviolet absorber before being irradiated with light having a wavelength in a region necessary for fixing. When the light-fixing type heat-sensitive recording layer is fixed, the wavelength of the region necessary for fixing is sufficiently transmitted and the visible light transmittance is also high, which may hinder the fixing of the heat-sensitive recording layer. Absent. This UV absorber precursor is preferably contained in microcapsules. Further, as the compound contained in the light transmittance adjusting layer, there is disclosed in JP-A-9-192.
The compounds described in JP-A-8 are listed.

The UV absorber precursor may function as a UV absorber by reacting with light or heat after the irradiation of light having a wavelength in a region necessary for fixing the thermosensitive recording layer by irradiation with light is completed. Most of the light having a wavelength in the region necessary for fixing in the ultraviolet region is absorbed by the ultraviolet absorber, the transmittance is lowered, and the light resistance of the thermosensitive recording material is improved, but there is no visible light absorption effect. Therefore, the transmittance of visible light is substantially unchanged. At least one light transmittance adjusting layer can be provided in the heat sensitive recording material, and most preferably it is formed between the heat sensitive recording layer and the outermost protective layer. You may make it double. The characteristics of the light transmittance adjusting layer can be arbitrarily selected according to the characteristics of the heat-sensitive recording layer.

The coating liquid for forming the light transmittance adjusting layer (coating liquid for light transmittance adjusting layer) is obtained by mixing the above components.
The coating solution for the light transmittance adjusting layer can be formed by coating with a known coating method such as a bar coater, an air knife coater, a blade coater, and a curtain coater. The light transmittance adjusting layer may be coated simultaneously with the heat-sensitive recording layer or the like. For example, a coating liquid for forming the heat-sensitive recording layer may be applied, the heat-sensitive recording layer may be dried once, and then the light-transmittance adjusting layer may be formed on the layer. Good. The solid coating amount of the light transmittance adjusting layer is 0.8 to
4.0 g / m ² is preferred.

(Intermediate Layer) In the present invention, when the thermosensitive recording layer has a laminated structure of thermosensitive coloring layers having different hues, an intermediate layer for preventing color mixture or the like is provided between the thermosensitive recording layers. be able to. The intermediate layer is not particularly limited and can be formed using a water-soluble polymer compound or the like. Examples of the water-soluble polymer compound include polyvinyl alcohol, modified polyvinyl alcohol, methyl cellulose, sodium polystyrene sulfonate, styrene-maleic acid copolymer, gelatin and /
Alternatively, those comprising a zetillane derivative, polyethylene glycol and / or a polyethylene glycol derivative are preferred.

Further, the inorganic layered compound can be suitably added to the intermediate layer. When the intermediate layer contains the inorganic layered compound, color transfer can be prevented by suppressing / preventing mass transfer between layers, and raw storage property and color image storage property are improved by suppressing supply of oxygen. Can be made.

(Protective Layer) In the thermal recording material of the present invention, a protective layer may be provided on the surface of the thermal recording layer, if necessary. Two or more protective layers may be laminated if necessary. As the binder preferably used for the protective layer, modified polyvinyl alcohol (silanol-modified polyvinyl alcohol,
Long-chain alkyl ether-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, etc.), polyvinyl alcohol silicone-modified polymer, carboxymethyl cellulose, hydroxyethyl cellulose, etc., may be used alone or in combination of two or more kinds. You may.

The protective layer preferably contains a pigment. As the pigment, inorganic ultrafine particles are preferable, and examples of the inorganic ultrafine particles include colloidal silica, zirconia oxide, barium sulfate, aluminum oxide (alumina), zinc oxide, magnesium oxide, calcium oxide, cerium oxide, titanium oxide and the like. These may be used alone or in combination of two or more.

The protective layer is preferably prepared by applying a protective layer coating solution containing silanol-modified polyvinyl alcohol and colloidal silica onto a heat-sensitive recording layer using a bar coater, air knife coater, blade coater, curtain coater or the like. Apply and dry. However, the protective layer may be applied at the same time as the heat-sensitive recording layer by a superposition method, or after the heat-sensitive recording layer or the like is applied, the heat-sensitive recording layer or the like may be dried and then applied. The solid coating amount of the protective layer is preferably 0.1 to 3 g / m ² , and 0.3 to ² .
0 g / m ² is more preferable. If the coating amount is large, the thermal sensitivity is remarkably lowered, and if the coating amount is too low, the function as a protective layer (friction resistance, lubricity, scratch resistance, etc.) cannot be exhibited. Further, after coating the protective layer, a calendering treatment may be carried out if necessary.

(Support) Examples of the support used in the present invention include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate film, polystyrene films, polypropylene films and polyethylene films. In addition to plastic films such as polyolefin films, polyimide films, polyvinyl chloride films, polyvinylidene chloride films, polyacrylic acid copolymer films, and polycarbonate films,
Examples thereof include paper, synthetic paper, paper having a plastic resin layer, and the like, and a support having the plastic film layer is preferable. These may be transparent or opaque, and may be used alone.
You may use 2 or more types together.

Suitable examples of the support having the plastic layer include those having a layer of a thermoplastic resin formed on both sides of the base paper or at least on the side on which the recording layer is formed. For example, (1) A base paper on which a thermoplastic resin is melt-extrusion coated, (2) A base paper on which a gas barrier layer is applied on a melt-extrusion-coated thermoplastic resin,
(3) Plastic paper with low oxygen permeability of the base paper adhered, (4) Thermoplastic resin provided by melt extrusion on the surface of the plastic film adhered to the base paper, (5) Thermoplastic base paper Examples include those obtained by melt extrusion coating a resin and then adhering a plastic film thereto.

Examples of the thermoplastic resin melt-extruded on the base paper include ethylene, an olefin polymer such as a homopolymer of α-olefin such as polyethylene and polypropylene, and a mixture of various polymers thereof, and ethylene. Preferable examples include random copolymers with vinyl alcohol. Examples of the polyethylene include LDPE
(Low density polyethylene), HDPE (high density polyethylene), L-LDPE (linear low density polyethylene) and the like.

The method for adhering the plastic film to the base paper is not particularly limited and may be appropriately selected from known lamination methods as described in "New Laminating Manual" edited by the Processing Technology Research Group. Suitable examples include so-called dry lamination, solventless dry lamination, dry lamination using an electron beam or ultraviolet curable resin, and hot dry lamination. In the present invention, among the above-mentioned supports, a base paper containing natural pulp as a main component and coated on both sides with an olefin polymer is particularly preferable.

[0068]

EXAMPLES The heat-sensitive recording material of the present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In addition, "part" in the following examples
Means "parts by mass" unless otherwise specified, and "%"
Means “% by mass” unless otherwise specified.

[Example 1] <Preparation of phthalated gelatin solution> Phthalated gelatin (trade name; MGP gelatin, manufactured by Nippi Collagen Co., Ltd.) 3
2 parts, 1,2-benzothiazolin-3-one (3.5%
Methanol solution, Daito Chemical Industry Co., Ltd. 0.914
3 parts and 367.1 parts of ion-exchanged water were mixed and dissolved at 40 ° C. to obtain a phthalated gelatin aqueous solution.

<Preparation of Alkali-Processed Gelatin Solution> 25.5 parts of alkali-treated low ionic gelatin (trade name: # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3. 5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd. 0.7286 parts, calcium hydroxide 0.153 parts, ion-exchanged water 143.6 parts are mixed and dissolved at 50 ° C. to prepare an alkali for emulsion preparation. A treated gelatin aqueous solution was obtained.

(1) Preparation of yellow heat-sensitive recording layer liquid <Preparation of diazonium compound-containing microcapsule liquid (a)> 2.2 parts of the following diazonium compound (A) (maximum absorption wavelength 420 nm) in 16.1 parts of ethyl acetate. , The following diazonium compound (B) (maximum absorption wavelength 420 nm)
2.2 parts, monoisopropyl biphenyl 4.8 parts, diphenyl phthalate 4.8 parts and diphenyl- (2,4
6-Trimethylbenzoyl) phosphine oxide (Brand name: Lucillin TPO, BASF Japan Ltd.)
(Manufactured by Mitsui Chemical Co., Ltd.) was added, and the mixture was heated to 40 ° C. and uniformly dissolved. A mixture of xylylene diisocyanate / trimethylol propane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the mixed solution (trade name; Takenate D119N (50% ethyl acetate solution), manufactured by Takeda Pharmaceutical Co., Ltd. ) 5.8 parts was added and the mixture was stirred uniformly to obtain a mixed solution (I).

Separately, the phthalated gelatin aqueous solution 68.
Ion-exchanged water 16.3 parts, Scrap AG-
0.34 parts of 8 (50%; manufactured by Nippon Seika Co., Ltd.) was added to obtain a mixed solution (II). The mixed solution (I) was added to the mixed solution (II), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 20 water is added to the obtained emulsion.
After adding parts to homogenize, the mixture was stirred at 40 ° C. and the encapsulation reaction was carried out for 3 hours while removing ethyl acetate. Then, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corporation) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corporation) were added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin is removed by filtration, and the concentration of the solid content of the capsule liquid is adjusted to 20.0%, and the diazonium salt compound-encapsulating microcapsule liquid (a) is added.
Got The particle size of the obtained microcapsules was measured by a particle size measurement (LA-700, manufactured by Horiba Ltd.),
The median diameter was 0.36 μm.

[0073]

[Chemical 10]

<Preparation of coupler compound emulsion (a)> The following coupler compound (C) was added to 33.0 parts of ethyl acetate.
Department and triphenylguanidine (Hodogaya Chemical Co., Ltd.)
9.9 parts, 4,4 '-(m-phenylenediisopropylidene) diphenol (trade name; bisphenol M)
(Mitsui Petrochemical Co., Ltd.)) 20.8 parts, 3,3
3.3 ', 3'-tetramethyl-5,5', 6,6'-tetra (1-propoxy) -1,1'-spirobisindane, 4- (2-ethylhexyloxy) benzenesulfonic acid 13.6 parts of amide (manufactured by Manac Co., Ltd.),
6.8 parts of 4-n-pentyloxybenzenesulfonic acid amide (manufactured by Manac Co., Ltd.) and calcium dodecylbenzenesulfonic acid (trade name: Pionine A-41-
C, 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd. 4.2
And parts were dissolved to obtain a mixed solution (III).

Separately, the alkali-treated gelatin aqueous solution 20
Ion-exchanged water (107.3 parts) was mixed with 6.3 parts to obtain a mixed solution (IV). The mixed liquid (III) was added to the mixed liquid (IV), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The obtained coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid concentration was 26.5%. The particle size of the obtained coupler compound emulsion was measured by particle size measurement (LA-700, manufactured by Horiba, Ltd.).
The median diameter was 0.21 μm. Further, to 100 parts of the coupler compound emulsion, 9 parts of SBR latex (trade name: SN-307, 48% liquid, manufactured by Sumika ABS Latex Co., Ltd.) whose concentration was adjusted to 26.5% was added. And uniformly stirred to obtain a coupler compound emulsion (a).

[0076]

[Chemical 11]

<Preparation of coating liquid (a)> The mass ratio of coupler compound / diazo compound in which the microcapsule liquid (a) containing the diazonium salt compound and the emulsion liquid (a) of the coupler compound are contained is 2. The mixture was mixed in a ratio of 2/1 to obtain a coating liquid (a) for the heat-sensitive recording layer.

(2) Preparation of magenta heat-sensitive recording layer liquid <Preparation of diazonium compound-containing microcapsule liquid (b)> 2.8 parts of the following diazonium compound (D) (maximum absorption wavelength 365 nm) in 15.1 parts of ethyl acetate. , Diphenyl phthalate 3.8 parts, phenyl 2-benzoyloxybenzoic acid ester 3.9 parts and the following ester compounds (trade name; light ester TMP, manufactured by Kyoei Yushi Kagaku Co., Ltd.)
4.2 parts and 0.1 part of calcium dodecylbenzene sulfonate (trade name Pionein A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) were added and heated,
It dissolved uniformly. A mixture of a xylylene diisocyanate / trimethylol propane adduct and a xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the liquid mixture (trade name: Takenate D119N (50%
2.5 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) 6) 0.8 parts was added and stirred uniformly to obtain a mixed solution (V).

Separately, the phthalated gelatin aqueous solution 65.
To 4 parts, 21.0 parts of ion-exchanged water was added and mixed to obtain a mixed solution (VI). Add the mixed solution (V) to the mixed solution (VI),
4 using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.)
It was emulsified and dispersed at 0 ° C. After 24 parts of water was added to the obtained emulsion and the mixture was homogenized, the mixture was stirred at 40 ° C. and the encapsulation reaction was carried out for 3 hours while removing ethyl acetate. After this,
Ion exchange resin Amberlite IRA68 (manufactured by Organo Corporation) 4.1 parts and Amberlite IRC50 (manufactured by Organo Corporation) 8.2 parts were added, and the mixture was further stirred for 1 hour.
Then, the ion exchange resin was removed by filtration, and the concentration of the solid content of the capsule liquid was adjusted to 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (b). The particle size of the obtained microcapsules was measured by the particle size measurement (LA
-700, measured by Horiba, Ltd.), and the median diameter was 0.43 μm.

[0080]

[Chemical 12]

<Preparation of Coupler Compound Emulsion (b)> The following coupler compound (E) was added to 36.9 parts of ethyl acetate.
5 parts and triphenylguanidine (Hodogaya Chemical Co., Ltd.)
14.0 parts, 4,4 '-(m-phenylene diisopropylidene) diphenol (trade name; bisphenol M)
(Mitsui Petrochemical Co., Ltd.)) 14.0 parts, 1,1- (p
-Hydroxyphenyl) -2-ethylhexane 14 parts,
3,3,3 ', 3'-tetramethyl-5,5', 6
3.5 parts of 6'-tetra (1-propoxy) -1,1'-spirobisindane, 3.5 parts of the following compound (G), 1.7 parts of tricresyl phosphate, diethyl maleate 0.8
And 4.5 parts of calcium dodecylbenzenesulfonate (trade name: Pionin A-41-C, 70% methanol solution, Takemoto Yushi Co., Ltd.) were dissolved to obtain a mixed solution (VII).

Separately alkali treated gelatin aqueous solution 206.
107.3 parts of ion-exchanged water is mixed with 3 parts, and the mixed solution (VI
II) was obtained. The mixed solution (VII) was added to the mixed solution (VIII), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The resulting coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid concentration was 24.5%.
A coupler compound emulsion (b) was obtained. The particle size of the obtained coupler compound emulsion was measured by a particle size measurement (LA-700, manufactured by Horiba Ltd.), and as a result, the median size was 0.22 μm.
It was m.

[0083]

[Chemical 13]

<Preparation of coating liquid (b)> The mass ratio of coupler compound / diazo compound in which the microcapsule liquid containing the diazonium salt compound (b) and the emulsion containing the coupler compound (b) are contained is 3. Mix to 5/1. Further, a polystyrene sulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) was added to the capsule liquid volume 10
The mixture was mixed with 0.2 parts by weight to obtain a coating liquid (b) for a heat-sensitive recording layer.

(3) Preparation of cyan thermosensitive recording layer liquid <electron donating dye precursor encapsulated microcapsule liquid (c)
Preparation of> In 18.1 parts of ethyl acetate, 7.6 parts of the following electron-donating dye (H), 1-methylpropylphenyl-phenylmethane and 1- (1-methylpropylphenyl)-
Mixture of 2-phenylethane (trade name; Hysol SA
S-310, manufactured by Nippon Oil Co., Ltd., 2.5 parts, and the following compound (I) (trade name; Irgaperm 2140 manufactured by Ciba-Geigy Co., Ltd.) 8.0 parts were added and heated to uniformly dissolve. A xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution) as a capsule wall material was added to the mixed solution,
7.2 parts by Takeda Pharmaceutical Co., Ltd. and polymethylene polyphenyl polyisocyanate (trade name; Millionate MR)
-200, 5.3 parts by Nippon Polyurethane Industry Co., Ltd.) was added and stirred uniformly to obtain a mixed solution (IX).

Separately, the phthalated gelatin aqueous solution 28.
8 parts of ion-exchanged water 9.5 parts, Scratch AG-8
(50%; Nippon Seika Co., Ltd.) 0.17 parts and sodium dodecylbenzene sulfonate (10% aqueous solution)
4.3 parts were added and mixed to obtain a mixed solution (X). The mixed solution (IX) was added to the mixed solution (X), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). To the obtained emulsion, 50 parts of water and 0.12 part of tetraethylenepentamine were added and homogenized, and the mixture was stirred at 65 ° C. to carry out an encapsulation reaction for 3 hours while removing ethyl acetate to obtain a solid content concentration of 33. The concentration was adjusted to be 100% to obtain a microcapsule liquid. The particle size of the obtained microcapsules was measured by a particle size measurement (LA-700, Horiba Ltd.).
As a result of measurement (measurement by manufacturing), the median diameter was 1.00 μm. Furthermore, to 100 parts of the microcapsule solution, a 25% sodium dodecylbenzenesulfonate aqueous solution (trade name; Neoperex F-25, manufactured by Kao Corporation)
Fluorescent brightener containing 6.0 parts and 4,4'-bistriazinylaminostilbene-2,2'-disulphone derivative (trade name; Kaycoll BXNL, Nippon Soda Co., Ltd.)
(Manufactured by Mfg. Co., Ltd.) was added thereto and the mixture was stirred uniformly to obtain a microcapsule dispersion liquid (c).

[0087]

[Chemical 14]

<Preparation of Electron Accepting Compound Dispersion (c)>
To 11.3 parts of the phthalated gelatin aqueous solution, 30.1 parts of ion-exchanged water, 15 parts of the exemplified compound 1 and 3.8 parts of a 2% sodium 2-ethylhexylsuccinate aqueous solution were added, and the mixture was dispersed overnight in a ball mill. After that, a dispersion liquid was obtained. The solid content concentration of this dispersion was 26.6%. To 100 parts of the dispersion, 4 parts of the alkali-treated gelatin aqueous solution was added.
After adding 5.2 parts and stirring for 30 minutes, ion-exchanged water was added so that the solid content concentration of the dispersion was 23.5% to obtain an electron-accepting compound dispersion (c).

<Preparation of coating liquid (c)> The above-mentioned microcapsule liquid (c) containing an electron-donating dye precursor in the inside and the above-mentioned electron-accepting compound dispersion liquid (c) were used as an electron-accepting compound / electron-donating dye precursor. Were mixed so that the mass ratio was 10/1 to obtain a coating liquid (c).

(4) Preparation of coating liquid for intermediate layer Alkali-treated low ionic gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.) 100.0 parts, 1,2-
Benzothiazolin-3-one (3.5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd.) (3.876 parts), calcium hydroxide (0.5 parts), ion-exchanged water (521.643 parts) were mixed, and the mixture was heated to 50 ° C. And dissolved to obtain an aqueous gelatin solution for preparing the intermediate layer.

Aqueous gelatin solution 10.0 for preparing the intermediate layer
Part, sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0%)
Aqueous solution) 0.05 part, boric acid (4.0% aqueous solution) 1.5
Parts, polystyrenesulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) 0.19 parts, 4% aqueous solution of the following compound (J) (manufactured by Wako Pure Chemical Industries, Ltd.) 3.42 parts, the following compounds (J ') (Wako Pure Chemical Industries, Ltd.) 4% aqueous solution 1.13
Parts and ion-exchanged water 0.67 parts were mixed to obtain a coating solution for the intermediate layer.

[0092]

[Chemical 15]

(5) Preparation of coating liquid for adjusting light transmittance <Preparation of UV absorber precursor microcapsule liquid> 71 parts of ethyl acetate was used as a UV absorber precursor [2-allyl-6- (2H-benzotriazole). -2-yl) -4-
t-octylphenyl] benzenesulfonate 14.5
Parts, 5.0 parts of 2,2'-t-octylhydroquinone,
α-Methylstyrene dimer (trade name: MSD-10
0, 12 parts by Mitsui Chemicals, Inc., calcium dodecylbenzene sulfonate (trade name: Pionine A-41-C (7
0% methanol solution) and Takemoto Yushi Co., Ltd.) 0.45 parts were dissolved and uniformly dissolved. 54.7 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.)) was added to the above mixture as a capsule wall material, and stirred uniformly. Then, an ultraviolet absorber precursor mixed solution was obtained.

Separately, 52 parts of itaconic acid-modified polyvinyl alcohol (trade name: KL-318, manufactured by Kuraray Co., Ltd.) was mixed with 8.9 parts of a 30% phosphoric acid aqueous solution and 532.6 parts of ion-exchanged water to prepare an ultraviolet absorber. P for precursor microcapsule liquid
A VA aqueous solution was prepared.

The above UV absorber precursor mixed solution was added to 516.06 parts of the PVA aqueous solution for the UV absorber precursor microcapsule solution, and the mixture was heated at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). It was emulsified and dispersed. After adding 254.1 parts of ion-exchanged water to the obtained emulsion and homogenizing it, the encapsulation reaction was carried out for 3 hours while stirring at 40 ° C. After this, ion exchange resin Amberlite MB
3 (manufactured by Organo Corporation) 94.3 parts was added, and the mixture was further stirred for 1 hour. Then, the ion exchange resin was filtered off, and the concentration of the solid content of the capsule liquid was adjusted to 13.5%. The particle size of the obtained microcapsules was measured by a particle size measurement (LA-700, manufactured by Horiba Ltd.), and the median size was 0.23 ± 0.05 μm. A carboxy-modified styrene butadiene latex (trade name: SN-307, (48%
Aqueous solution), Sumitomo Nogatak Co., Ltd.) 2.416 parts,
39.5 parts of ion-exchanged water were mixed to obtain an ultraviolet absorber precursor microcapsule liquid.

<Preparation of Coating Liquid for Light Transmittance Adjustment Layer> 1000 parts of the above-mentioned ultraviolet absorber precursor microcapsule liquid, fluorine-based surfactant (trade name: Megafac F-120, 5
% Aqueous solution, Dainippon Ink and Chemicals, Inc., 5.2 parts, 4
% Sodium hydroxide aqueous solution 7.75 parts, sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution) 73.39
The parts were mixed to obtain a coating liquid for a light transmittance adjusting layer.

(6) Preparation of coating liquid for protective layer <Preparation of polyvinyl alcohol solution for protective layer> Vinyl alcohol-alkyl vinyl ether copolymer (trade name:
EP-130, manufactured by Denki Kagaku Kogyo Co., Ltd., 160 parts, mixed solution of sodium alkylsulfonate and polyoxyethylene alkyl ether phosphate (trade name: Neoscore CM-57, (54% aqueous solution), Toho Chemical Industry ( stock)
(Manufactured), 8.74 parts, and ion-exchanged water 3832 parts are mixed,
It melt | dissolved at 0 degreeC for 1 hour, and the polyvinyl alcohol solution for uniform protective layers was obtained.

<Preparation of Pigment Dispersion Liquid for Protective Layer> Barium sulfate (trade name: BF-21F, barium sulfate content 93%)
As mentioned above, in 5 parts of Sakai Chemical Industry Co., Ltd., anionic special polycarboxylic acid type polymer activator (trade name: Poise 532A)
(40% aqueous solution), manufactured by Kao Co., Ltd. (0.2 parts) and ion-exchanged water (11.8 parts) were mixed and dispersed with a Dynomill to prepare a barium sulfate dispersion liquid. This dispersion has a particle size measurement (L
A-910, measured by Horiba, Ltd.), and the median diameter was 0.15 μm or less. For 45.6 parts of the barium sulfate dispersion liquid, colloidal silica (trade name:
Snowtex O (20% aqueous dispersion), Nissan Chemical Co., Ltd.
(Manufactured by Mitsui Chemicals Co., Ltd.) 8.1 parts was added to obtain the desired pigment dispersion for protective layer.

<Preparation of Matting Agent Dispersion for Protective Layer> Wheat Starch (trade name: Wheat Starch S, Shinshin Food Industry Co., Ltd.) 22
An aqueous dispersion of 1-2 benzisothiazoline 3-one in 0 part (trade name: PROXEL BD, ICI Co., Ltd.)
3.81 parts of ion-exchanged water and 1976.19 parts of ion-exchanged water were mixed and uniformly dispersed to obtain a protective layer matting agent dispersion.

<Preparation of Coating Solution for Protective Layer> 1000 parts of the polyvinyl alcohol solution for the protective layer was added to a fluorosurfactant (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink and Chemicals, Inc.). 40 parts, sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution) 50 parts, pigment dispersion liquid for the protective layer 49.87 parts, for the protective layer 16.65 parts of the matting agent dispersion liquid and 48.7 parts of zinc stearate dispersion liquid (trade name: Hydrin F115, 20.5% aqueous solution, manufactured by Chukyo Yushi Co., Ltd.) are uniformly mixed to obtain a coating liquid for protective layer. It was

<Preparation of Support> (Preparation of Coating Solution for Undercoat Layer) Enzyme-decomposed gelatin (average molecular weight: 10,000, PAGI viscosity: 1.5 mPa · s)
(15 mP), PAGI method jelly strength: 20 g) (40 parts) was added to 60 parts of ion-exchanged water, and dissolved by stirring at 40 ° C. to prepare a gelatin aqueous solution for the undercoat layer. Separately water-swellable synthetic mica (aspect ratio: 1000, trade name: Somasif M
E100, manufactured by Corp Chemical Co., Ltd.) and 8 parts of water and 92 parts of water, and then wet-dispersed with Viscomill to obtain an average particle size of 2.0.
A mica dispersion of μm was obtained. Water was added to this mica dispersion so that the mica concentration was 5%, and the mixture was uniformly mixed to prepare a desired mica dispersion.

120 parts of water and 556 parts of methanol were added to 100 parts of the 40% aqueous gelatin solution for the undercoat layer at 40 ° C., thoroughly mixed with stirring, and then 5% of the mica dispersion 20.
8 parts were added and mixed thoroughly with stirring, and 4.8 parts of a 1.66% polyethylene oxide-based surfactant was added. Then, the liquid temperature was maintained at 35 ° C to 40 ° C, and 7.3 parts of a gelatin hardener of an epoxy compound was added to the undercoat layer coating liquid (5.7 parts).
%) Was prepared to obtain a coating liquid for undercoat.

(Preparation of Support with Undercoat Layer) LBPS5
Wood pulp consisting of 0 parts and 50 parts LBPK is 300 ml canadian freeness by a disc refiner.
Beaten to 0.5 parts of epoxidized behenic acid amide, 1.0 part of anionic polyacrylamide, 1.0 part of aluminum sulfate, 0.1 part of polyamide polyamine epichlorohydrin, and 0.5 part of cationic polyacrylamide to the pulp. A base paper having a basis weight of 114 g / m ² was made into a paper by adding in a dry mass ratio with a Fourdrinier paper machine, and calendered to adjust the thickness to 100 μm.

Next, after corona discharge treatment was applied to both sides of the base paper, polyethylene was applied to a resin thickness of 36 using a melt extruder.
The resin layer was coated so as to have a thickness of μm, and a resin layer made of a matte surface was formed (this surface is referred to as a “back surface”). Next, using a melt extruder on the side opposite to the surface on which the resin layer was formed, polyethylene containing 10% of anatase type titanium dioxide and a trace amount of ultramarine blue was coated to a resin thickness of 50 μm to form a glossy surface. A resin layer was formed (this surface is referred to as "front surface"). After the corona discharge treatment was applied to the polyethylene resin coated surface on the back side, aluminum oxide (trade name; alumina sol 1 was used as an antistatic agent.
00, manufactured by Nissan Chemical Industries, Ltd./silicon dioxide (trade name;
Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) = 1/2
(Mass ratio) is dispersed in water and the mass after drying is 0.2 g /
m ^{2 was} applied. Next, after subjecting the polyethylene resin-coated surface of the front surface to corona discharge treatment, the undercoat layer coating solution was applied so that the coating amount of mica was 0.26 g / m ² .
A support with an undercoat layer was obtained.

<Coating of Coating Solution for Each Thermal Recording Layer> On the surface of the support with the undercoat layer, from the bottom, the coating solution for thermal recording layer (c), the coating solution for intermediate layer (intermediate layer A), Coating solution (b) for the thermosensitive recording layer, coating solution for the intermediate layer (intermediate layer B), coating solution for the thermosensitive recording layer (a), coating solution for the light transmittance adjusting layer, coating solution for the protective layer In this order, 7 layers are applied continuously at the same time, 30 ℃ ・ 30% humidity, and 40 ℃ ・ 3 humidity.
Each was dried under the condition of 0% to obtain a multicolor thermosensitive recording material. At this time, the coating amount of the coating liquid (a) for the heat-sensitive recording layer was adjusted so that the coating amount of the diazonium compound (A) contained in the liquid was 0.078 g / m ^{2 in} terms of solid coating amount. The coating amount of the coating liquid (b) for the heat-sensitive recording layer was adjusted so that the coating amount of the diazonium compound (D) contained in the liquid was 0.206 g / m ^{2 in} terms of the solid coating amount. The coating amount of the coating liquid (c) for the recording layer is 0.3 when the coating amount of the electron-donating dye (H) contained in the liquid is the solid coating amount.
The coating was carried out by adjusting so as to be 55 g / m ² .

Further, the coating liquid for the intermediate layer B has a solid coating amount of 2.39 g / m ² , the coating liquid for the intermediate layer A has a solid coating amount of 3.34 g / m ² , and the light transmittance adjustment is performed. The layer coating solution was coated so that the solid coating amount was 2.35 g / m ² , and the protective layer coating liquid was coated so that the solid coating amount was 1.39 g / m ² .

(Evaluation) (i) Thermal recording Thermal recording was performed by the following method using a thermal head KST (trade name: manufactured by Kyocera) and an ultraviolet lamp. After exposure for 10 seconds under an ultraviolet lamp with an emission center wavelength of 450 nm and an output of 40 W, it is further exposed for 30 seconds under an ultraviolet lamp with an emission center wavelength of 365 nm and an output of 40 W, and finally the recording energy per unit area is 132 to 171 m.
Printing was performed in the range of J / mm ² , and a cyan image was obtained.

(Ii) Evaluation of image storability The cyan density of the obtained multicolor heat-sensitive recording material is X-rit.
It was measured with an e model 310 (X-rite (R filter), manufactured by Incorporated).
Next, using a weather meter (manufactured by Atlas, Ci65 type), the output at a wavelength of 420 nm is 0.9 w / cm ^2.
Artificial sunlight of 1. was continuously irradiated for 11 days on the multicolor thermosensitive recording material whose cyan concentration was measured, and the cyan density after 11 days of continuous irradiation was measured in the same manner as before irradiation. The image residual rate (%) after exposure is the value obtained by multiplying the cyan density after continuous irradiation for 11 days at the location where the cyan density was 1.0 before irradiation by 100.
The image storability was evaluated. The results are shown in Table 2.

(Iii) Evaluation of exposed background coloration Furthermore, the density of the background part of the multicolor heat-sensitive recording material after the continuous irradiation for 11 days was measured by using X-rite model 310 (X
-Rite (B filter), Incorporate
The color of the exposed skin was evaluated. The results are shown in Table 2.

Example 2 In Example 1 <Preparation of Electron-Accepting Compound Dispersion (c)>, Exemplified Compound 1
A multicolor heat-sensitive recording material of Example 2 was prepared in the same manner as in Example 1 except that the above-mentioned Compound 2 was used, and the same evaluation was performed. The results are shown in Table 2.

Example 3 In <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1, Exemplified Compound 1
A multicolor heat-sensitive recording material of Example 3 was prepared in the same manner as in Example 1 except that the above-mentioned Compound 5 was used, and the same evaluation was performed. The results are shown in Table 2.

Example 4 In <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1, Exemplified Compound 1
A multicolor heat-sensitive recording material of Example 4 was prepared in the same manner as in Example 1 except that the above-mentioned Compound 8 was changed to the same evaluation. The results are shown in Table 2.

Comparative Example 1 In <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1, Exemplified Compound 1
Was changed to the compound A represented by the following structural formula, and a multicolor heat-sensitive recording material of Comparative Example 1 was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0114]

[Chemical 16]

[Comparative Example 2] Exemplified Compound 1 in <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1
Was changed to the compound B represented by the following structural formula, and a multicolor heat-sensitive recording material of Comparative Example 2 was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0116]

[Chemical 17]

[Comparative Example 3] Exemplified Compound 1 in <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1
Was changed to the compound C represented by the following structural formula, and a multicolor heat-sensitive recording material of Comparative Example 3 was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0118]

[Chemical 18]

[Comparative Example 4] In <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1, Exemplified Compound 1
Was changed to Compound D represented by the following structural formula, and a multicolor heat-sensitive recording material of Comparative Example 4 was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0120]

[Chemical 19]

[Comparative Example 5] In <Preparation of Electron-Accepting Compound Dispersion (c)> in Example 1, Exemplified Compound 1
Was changed to the compound E represented by the following structural formula, and a multicolor heat-sensitive recording material of Comparative Example 5 was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

[0122]

[Chemical 20]

[Comparative Example 6] The same as Example 1 except that the microcapsule dispersion liquid (c) in Example 1 was changed to a solid dispersion liquid (c) of an electron-donating colorless dye prepared by the following method. Then, a multicolor heat-sensitive recording material of Comparative Example 6 was produced and evaluated in the same manner. The results are shown in Table 2.

<< Solid Dispersion of Electron Donating Colorless Dye (c)
Preparation of phthalated gelatin aqueous solution (33.9 parts), ion-exchanged water (30.1 parts), electron donating colorless dye (H) 1
5 parts, 3.8% aqueous solution of 2% sodium 2-ethylhexylsuccinate was added, and the mixture was dispersed overnight in a ball mill,
Further, ion-exchanged water was added so that the solid content concentration was 8% to prepare a solid dispersion liquid (c) of the electron-donating colorless dye.

[Comparative Example 7] A comparative example was carried out in the same manner as in Example 3 except that the microcapsule dispersion (c) in Example 3 was changed to the solid dispersion (c) of the electron-donating colorless dye. A multicolor heat-sensitive recording material of No. 7 was produced and evaluated in the same manner. The results are shown in Table 2.

[0126]

[Table 2]

The results in Table 2 show that the electron-accepting compound represented by the general formula (1) was used, and the electron-donating colorless dye was used in microcapsules encapsulated in microcapsules. It is shown that the heat-sensitive recording materials have an improved image residual ratio after light exposure as compared with the multicolor heat-sensitive recording materials of Comparative Examples 1 to 7 without increasing the background coloration after light exposure.

[0128]

INDUSTRIAL APPLICABILITY The present invention can provide a heat-sensitive recording material which has both good image storability in a bright place and reduction of light exposure background coloring.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Sato             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. F term (reference) 2H026 BB30 BB41 FF03 FF05

Claims (2)

[Claims] 1. A heat-sensitive recording material having at least one heat-sensitive recording layer provided on a support, wherein at least one of the heat-sensitive recording layers is represented by the following general formula (1) together with an electron-donating colorless dye. A heat-sensitive recording material containing at least one electron-accepting compound as described above, and the electron-donating colorless dye is encapsulated in microcapsules. [Chemical 1] (In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group. R ^{11 to} R ¹⁴ each independently represent a hydrogen atom or an alkyl group.) 2. The heat-sensitive recording according to claim 1, wherein the electron-accepting compound represented by the general formula (1) is an electron-accepting compound represented by the following general formula (2). material. [Chemical 2] (In the general formula (2), R ³ represents an alkyl group.)