JP2003145930A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording material, with which a high contrast and clear image can be stably formed excellent in the whiteness of a ground part and especially in the biopreservability to the whiteness without impairing the color developing density of an image part. SOLUTION: In the heat sensitive recording material having a heat sensitive recording layer at least including a diazonium salt compound and a coupler developing color through the coupling reaction with the diazonium salt compound, the diazonium salt compound is involved in microcapsules together with an aromatic hydrocarbon and a thermal acid generator.

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 diazo compound-based heat-sensitive recording material which can be fixed and has excellent storability.

[0002]

2. Description of the Related Art A heat-sensitive recording material for recording an image by supplying heat with a thermal head or the like is relatively inexpensive, its recording device is simple and reliable, and maintenance is not required. It is popular. Under such circumstances, in recent years, there have been particularly strong demands for higher performance such as higher image quality and improved storage stability.
Research on image quality, storability, etc. has been earnestly conducted.

However, in general, in the case of a heat-sensitive recording material containing a diazonium salt compound as a color-forming component, the activity of the diazonium salt compound itself is very high, so that the diazonium salt compound is gradually thermally decomposed even in a dark place. Therefore, there is a drawback that the shelf life as a recording material is short because it loses reactivity. Here, when the diazonium salt compound is decomposed, various photodecomposition reaction products are generated, and as a result, it has absorptivity in the visible region, so-called photodegradation stain is liable to occur, and the whiteness of the background is significantly reduced. To do.

As one of means for improving this drawback, there is a method of encapsulating a diazonium salt compound in a microcapsule, which is used as a recording material by separating the diazonium salt compound from water, a base or the like having a decomposition promoting action. Can dramatically improve the shelf life of (Satoshi Usami et al., The Electrophotographic Society of Japan, Vol. 26, No. 2 (19
87) p.115-125). The microcapsules have a glass transition temperature of the capsule wall slightly higher than room temperature (thermoresponsive microcapsules), so that the walls show a substance impermeable property at room temperature and a substance permeability at a glass transition temperature or higher. By encapsulating a diazonium salt compound in the capsule wall and allowing a coupler and a base to be present outside the capsule, the diazonium salt compound can be stably retained for a long period of time, and a colored image can be easily formed by heating, Moreover, the image can be fixed (optically fixed) by light irradiation.

However, the decomposition reaction of the diazonium salt compound cannot be completely prevented even when it is microencapsulated, and it is possible to avoid coloring due to photodegradation stains due to the presence of various photolysis reaction products. Can not. This not only deteriorates the whiteness of the recording surface of the heat-sensitive recording material containing a diazonium salt compound as a color-forming component and impairs the quality of the recording material, but also the formed image has a high background density, resulting in a high image contrast. As a result, the image quality is significantly deteriorated and the image quality is also impaired. However, if the reactivity of the diazonium salt compound itself is simply lowered, the color density may be lowered, and it is necessary to improve the whiteness while maintaining the colorability.

In response to the above coloring problem, the whiteness of the unrecorded recording surface and the storage stability (raw storability) with respect to the whiteness are increased, and the non-image area after recording (after optical fixing) is improved. In recent years, various studies have been made as a technique for improving the whiteness of the (ground portion). For example, Japanese Patent Application Laid-Open No. 62-55188 discloses a technique in which a microcapsule contains a diazo compound and a compound capable of generating a free radical upon irradiation with light. According to the technique, white color of the background portion after photofixing is disclosed. It is said that the sex can be improved to some extent. However, the whiteness of the unrecorded recording surface can be maintained stably for a long period of time without being impaired, that is, the shelf life is insufficient, and the raw storability that completely avoids the coloring of the background can not be obtained. .

Further, Japanese Unexamined Patent Publication (Kokai) No. 8-324129 proposes a technique of encapsulating an aromatic hydrocarbon such as diphenyl phthalate in a microcapsule together with a diazonium salt compound, which is excellent in preservability and whiteness of the background. It is stated to that effect. However, the unrecorded recording surface can be stably maintained for a long period of time without impairing the whiteness, that is, it is still insufficient in terms of shelf life, coloring of the background part is completely avoided, and the background part of high whiteness is colored. It has not been possible to provide a heat-sensitive recording material which can be stably maintained for a long period of time and stably form a high-contrast image.

JP-A-6-344667 and JP-A-7-34467
In JP-A-175165, it is described that, in a diazo heat-sensitive recording material, a sulfonic acid compound or a sulfuric acid dialkyl ester compound is used in combination to enhance the temporal stability of the diazonium salt compound and suppress the generation of stains on the background. ing. Also in these publications, similarly to the above, in terms of shelf life capable of holding an unrecorded recording surface stably for a long period of time without impairing whiteness, coloration of the background part is completely avoided, and white color is obtained. It has not been possible to provide a heat-sensitive recording material capable of stably forming a high-contrast image by keeping a highly colored background portion without coloring for a long time.

As described above, although various performances (quality, storability, etc.) relating to recording materials have been improved by recent researches and the like, coloring of the background part is completely avoided, and the background part of high whiteness is obtained. It is difficult to maintain high color contrast for a long time and to stably form a high-contrast image, and further improvement is required from the viewpoint of the quality of heat-sensitive recording materials containing a diazonium salt compound as a coloring component and the image quality. It was

[0010]

Therefore, under the recent circumstances in which high performance such as high image quality and storage stability (particularly, raw storability) are required as described above, the coloring property is maintained. However, it has a recording surface with high whiteness (background) and has excellent storage stability (raw storage) that does not impair the whiteness of the background for a long period of time. At present, a thermal recording material capable of stably forming a high image has not been provided yet.

An object of the present invention is to solve the above-mentioned problems in the prior art and achieve the following objects. That is, the present invention is particularly excellent in whiteness of a non-image part (background part) and storage stability (raw storage property) with respect to the whiteness, a high-contrast and clear image without impairing the color density of the image part. It is an object of the present invention to provide a heat-sensitive recording material that can be stably formed.

[0012]

Means for solving the problems Means for solving the above problems are as follows. <1> A thermosensitive recording material having a thermosensitive recording layer on a support, the thermosensitive recording layer containing at least a diazonium salt compound and a coupler that causes a color reaction by coupling reaction with the diazonium salt compound, wherein the diazonium salt compound is an aromatic hydrocarbon. A heat-sensitive recording material characterized by being encapsulated in a microcapsule together with a thermal acid generator.

<2> The thermal acid generator is at least one selected from an arylalkylsulfonyl compound represented by the following general formula (I) and a sulfuric acid dialkyl ester compound represented by the following general formula (II). The heat-sensitive recording material of <1>.

[0014]

[Chemical 3] [In general formula (I), Ar represents an aryl group, and R represents an alkyl group, a cycloalkyl group, or an aralkyl group. ]

[0015]

[Chemical 4] [In general formula (II), R'represents an alkyl group having 24 or less carbon atoms and a cycloalkyl group having 24 or less carbon atoms. ]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-sensitive recording material of the present invention, a diazonium salt compound is encapsulated in a microcapsule together with an aromatic hydrocarbon and a thermal acid generator shown below. Hereinafter, the heat-sensitive recording material of the present invention will be described in detail.

<Heat-sensitive recording material> The heat-sensitive recording material of the present invention comprises at least a heat-sensitive recording layer on a support, and the heat-sensitive recording layer may be composed of either a single layer or a plurality of layers. Accordingly, other layers such as a light transmittance adjusting layer and a protective layer may be further included.

<Heat-sensitive recording layer> The heat-sensitive recording layer comprises a diazonium salt compound, a coupler that causes a color reaction by coupling reaction with the diazonium salt compound, an aromatic hydrocarbon, and a thermal acid generator. If necessary, it may contain other components such as a base.

In the present invention, it is particularly important that the diazonium salt compound is encapsulated in a microcapsule together with the aromatic hydrocarbon and the thermal acid generator, and a heat-sensitive recording material containing any one of them together with the diazonium salt compound. In comparison, extremely excellent whiteness and raw storability capable of maintaining the whiteness stably for a long time can be ensured. Generally, the recording surface (background part) of the material containing the diazonium salt compound
Although the coloring tends to decrease in whiteness depending on the storage environment such as high temperature and high humidity, a heat-sensitive recording material having storage stability without being affected by the storage environment can be obtained.

(Aromatic Hydrocarbon) In the present invention, the aromatic hydrocarbon is also contained in the microcapsules containing the diazonium salt compound.

The above-mentioned aromatic hydrocarbon can be appropriately selected and used from known aromatic hydrocarbons within a range that does not impair the effects of the present invention. As the aromatic hydrocarbon that can be used in the present invention, arylalkane, alkylnaphthalene, biphenyl and terphenyl are preferable.
Further, these compounds may be substituted with an alkyl group. As the above-mentioned aromatic hydrocarbon, one having a small polarity is preferable, and one having a boiling point of 250 ° C. or higher is also preferable.

Specific examples of preferred aromatic hydrocarbons include ethylbenzene as the arylalkane.
Cumene, butylbenzene, isobutylbenzene, t-butylbenzene, amylbenzene, tetrahydronaphthalene, o-xylene, m-xylene, p-xylene, 1,
2-diethylbenzene, 1,3-diethylbenzene,
1,4-diethylbenzene, o-cymene, m-cymene,
p-cymene, indane, mesitylene, diphenylmethane, triphenylmethane, 1-phenyl-1-butylphenylmethane, 1,1-diphenylethane, 1-phenyl-1-ethylphenylethane, 1-phenyl-1-propylphenylethane , 1-phenyl-1-butylphenylethane, 1-phenyl-1-xylylethane, 1,
1-ditolylethane, 2,2-diphenylpropane, phenethylcumene, bibenzyl and the like can be mentioned, 1-phenyl-1-butylphenylmethane, 1-phenyl-1-butylphenylethane, 1-phenyl-1-xylylethane, phenethylcumene. Is particularly preferable.

Similarly, as the alkylnaphthalene, α-methylnaphthalene, β-methylnaphthalene, α
-Ethylnaphthalene, β-ethylnaphthalene, dimethylnaphthalene, diisopropylnaphthalene, triisopropylnaphthalene, KSK-oil (alkylnaphthalene) and the like can be mentioned, with diisopropylnaphthalene and triisopropylnaphthalene being particularly preferable.

As the above-mentioned biphenyl (alkylbiphenyl), biphenyl, monoisopropylbiphenyl, isoamylbiphenyl, diisopropylbiphenyl, 4-
Examples include ethyl biphenyl, 4,4′-di-t-butyl biphenyl, THEMS 700 (diethyl biphenyl), THEMS 800 (triethyl biphenyl), 9,10-dihydrophenanthrene, fluorene, 9-ethyl fluorene, and monoisopropyl biphenyl. , Diisopropylbiphenyl is particularly preferred.

Similarly, examples of the terphenyl (alkyl terphenyl) include o-terphenyl, m-terphenyl and p-terphenyl. In addition, α-methylstyrene dimer as the styrene dimer, 4,5,6,7-tetramethylindene, 4,5,6,7-tetraethylindene as the alkylindene,
4,9-diethyl-5,6,7,8-tetrahydrobenzoindene, phenanthrene and the like can be mentioned, and α-methylstyrene dimer is particularly preferable.

The aromatic hydrocarbon is contained as a core substance of the microcapsule together with a diazonium salt compound described later, and preferably has a melting point of 150 ° C. or lower from the viewpoint that it is difficult to precipitate during the production of the capsule. Above all, 130 ℃
The following are more preferable.

In the present invention, the above aromatic hydrocarbons may be used alone or in combination of two or more. The content of the aromatic hydrocarbon is preferably 30 to 600 mass% and more preferably 60 to 300 mass% with respect to the diazonium salt compound described below. If the content is less than 30% by mass, the whiteness of the background portion during raw storage (raw storability) may decrease, and 600
If the content is more than mass%, the color density may decrease.

(Thermal Acid Generator) In the present invention, the microcapsules containing the diazonium salt compound also contain at least one thermal acid generator. here,
The "thermal acid generator" refers to a compound that hydrolyzes with time or heat to generate an acid. As described above, by encapsulating the diazonium salt compound in the microcapsules together with the aromatic hydrocarbon and the thermal acid generator, the whiteness of the non-image area and the raw storage stability that can maintain the whiteness for a long period of time are maintained. Further improvement can be achieved.

The thermal acid generator can be appropriately selected from known compounds capable of generating an acid with the passage of time or heat. Among these, a compound selected from an arylalkylsulfonyl compound represented by the following general formula (I) and a sulfuric acid dialkyl ester compound represented by the following general formula (II) is particularly preferable.

-Arylalkylsulfonyl compound-

[Chemical 5]

Ar in the general formula (I) represents an aryl group, and R represents an alkyl group, a cycloalkyl group or an aralkyl group. The aryl group, alkyl group, cycloalkyl group and aralkyl group may be substituted with a halogen atom, an alkoxy group, an acylamino group, an acyl group, a sulfonyl group, a nitrile group, an alkoxycarbonyl group, a carbamoyl group, a nitro group or the like. Good.

The above aryl group has 6 to 20 carbon atoms.
Examples of the aryl group include a phenyl group, a 4-methylphenyl group, a 3-methylphenyl group, a 2-methylphenyl group, a 4-chlorophenyl group, and a naphthyl group. Of these, an aryl group having 6 to 12 carbon atoms is preferable, and a phenyl group, a 4-methylphenyl group, and a 2-methylphenyl group are particularly preferable.

The above alkyl group has 1 to 12 carbon atoms.
Alkyl groups of, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
A tert-butyl group, n-octyl group, 2-ethylhexyl group, n-dodecyl group and the like can be mentioned. Of these, an alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group and an ethyl group are particularly preferable.

Examples of the above cycloalkyl group include:
Examples thereof include a cyclopentyl group and a cyclohexyl group.
Examples of the aralkyl group include an aralkyl group having a carbon number of 7 to 20, and examples thereof include a benzyl group, a methoxybenzyl group and an α-methylbenzyl group.

The total number of carbon atoms in the arylalkylsulfonyl compound represented by the general formula (I) is preferably 7-40, more preferably 7-25.

Specific examples of the arylalkylsulfonyl compound represented by the general formula (I) are shown below, but the invention is not limited thereto. For example, methyl benzene sulfonate, ethyl benzene sulfonate, propyl benzene sulfonate, methyl p-toluene sulfonate, methyl o-toluene sulfonate, ethyl p-toluene sulfonate, ethyl o-toluene sulfonate, methyl naphthalene sulfonate, Ethyl 4-methoxybenzenesulfonate, 2-butoxyethyl p-toluenesulfonate, 2-phenoxyethyl benzenesulfonate, benzyl 3-methoxycarbonylbenzenesulfonate, 2-nitroethyl benzenesulfonate, p-toluenesulfonic acid -3-acetaminopropyl etc. are mentioned.

-Sulfate dialkyl ester compound-

[Chemical 6]

In the general formula (II), R'is 24 carbon atoms.
The following alkyl group and cycloalkyl group having 24 or less carbon atoms are represented, and these may be further substituted with an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a nitro group or a halogen atom.

Examples of the alkyl group having 24 or less carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, i.
Examples thereof include so-pentyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-dodecyl group, octadecyl group and stearyl group. Among them, carbon number 2
An alkyl group having 12 carbon atoms is preferable, an alkyl group having 2 to 6 carbon atoms is more preferable, and an ethyl group, n-propyl group and n-butyl group are particularly preferable. Examples of the cycloalkyl group having 24 or less carbon atoms include a cyclopentyl group and a cycloalkyl group.

Specific examples of the sulfuric acid dialkyl ester compound represented by the general formula (II) are shown below, but the invention is not limited thereto. For example, diethylsulfate, di-n-propylsulfate, di-n-butylsulfate, bis (2-ethylhexyl) sulfate, dilaurylsulfate, distearylsulfate, bis (2-phenethyl) sulfate,
Bis (α-naphthylmethyl) sulfuric acid, dibenzyl sulfuric acid,
Bis (2-butoxyethyl) sulfuric acid, bis (2-phenoxyethyl) sulfuric acid, bis (2-octylthioethyl)
Sulfuric acid, bis [2- (4-tolyl) thioethyl] sulfuric acid, bis (4-nitroethyl) sulfuric acid, bis (2-chloroethyl) sulfuric acid, dicyclohexylsulfuric acid, bis (4-methylcyclohexyl) sulfuric acid, bis (4-methoxycyclohexyl) Sulfuric acid, vinyl chloride, bis (4-butylthiocyclohexyl) sulfuric acid and the like can be mentioned.

In the present invention, the thermal acid generator represented by at least one of the above general formulas (I) and (II) may be used alone or in combination of two or more. . The total content of the thermal acid generator is preferably 10 to 200 mass% and more preferably 20 to 100 mass% with respect to the diazonium salt compound described below. If the total content is less than 10% by mass, the whiteness of the non-image part (background part) may be low, and the whiteness during raw storage may be significantly reduced. If it exceeds 200% by mass, Fog during raw storage may increase.

In the present invention, the above-mentioned aromatic hydrocarbon and thermal acid generator are also encapsulated in the microcapsules encapsulating the diazonium salt compound. In this case, the content ratio (x: y) of the aromatic hydrocarbon (x) and the thermal acid generator (y) is preferably 20: 1 to 1: 2.
0: 1 to 1: 1 is more preferable.

In the present invention, a diazonium salt compound, which will be described later, which is a color-forming component, is encapsulated in the same microcapsule together with the above-mentioned aromatic hydrocarbon and thermal acid generator to give aromatic hydrocarbon and thermal acid generator. Whiteness of non-image part (background part),
And the raw storability for the whiteness can be significantly improved. As a result, in the non-image area, white can be maintained without being colored, and a clear and high-contrast image can be stably formed.

(Diazonium Salt Compound) Examples of the diazonium salt compound include compounds represented by the following formula (1). _{^{Ar-N 2 + X - ...}} (1) [In the formula, Ar represents an aromatic moiety, X ^- represents an acid anion. ]

The diazonium salt compound is a compound which causes a coupling reaction with a coupler described below when heated to develop a color, and which is decomposed by light. The maximum absorption wavelength of these can be controlled by the position and type of the substituent of the Ar portion.

Specific examples of the diazonium which forms a salt include 4- (p-tolylthio) -2,5-dibutoxybenzenediazonium and 4- (4-chlorophenylthio)-.
2,5-dibutoxybenzenediazonium, 4- (N,
N-dimethylamino) benzenediazonium, 4-
(N, N-diethylamino) benzenediazonium, 4
-(N, N-dipropylamino) benzenediazonium, 4- (N-methyl-N-benzylamino) benzenediazonium, 4- (N, N-dibenzylamino) benzenediazonium, 4- (N-ethyl-N) -Hydroxyethylamino) benzenediazonium, 4- (N, N-
Diethylamino) -3-methoxybenzenediazonium, 4- (N, N-dimethylamino) -2-methoxybenzenediazonium, 4- (N-benzoylamino)-
2,5-diethoxybenzenediazonium, 4-morpholino-2,5-dibutoxybenzenediazonium, 4-
Anilinobenzenediazonium, 4- [N- (4-methoxybenzoyl) amino] -2.5-diethoxybenzenediazonium, 4-pyrrolidino-3-ethylbenzenediazonium, 4- [N- (1-methyl-2- ( 4-Methoxyphenoxy) ethyl) -N-hexylamino]-
2-hexyloxybenzenediazonium, 4- [N-
(2- (4-Methoxyphenoxy) ethyl) -N-hexylamino] -2-hexyloxybenzenediazonium, 2- (1-ethylpropyloxy) -4- [di-
(Di-n-butylaminocarbonylmethyl) amino] benzenediazonium, 2-benzylsulfonyl-4-
[N-methyl-N- (2-octanoyloxyethyl)] aminobenzenediazonium and the like can be mentioned.

The maximum absorption wavelength λmax of the diazonium salt compound is preferably 450 nm or less, and 290 to 290
440 nm is more preferable. The above λmax is 450 nm
If it is on the long wavelength side, the raw storability may be deteriorated, and if it is on the shorter wavelength side than the above wavelength range, the image fixing property and the image storability may be deteriorated in combination with a coupler described later. , The hue of cyan color may deteriorate.

The diazonium salt compound preferably has 12 or more carbon atoms, a solubility in water of 1% or less, and a solubility in ethyl acetate of 5% or more. The diazonium salt compounds may be used alone or in combination of two or more depending on the purpose such as hue adjustment.

Among the above-mentioned diazonium salt compounds, the diazonium salt compounds represented by the following structural formulas (1) to (3) are more preferable in view of the hue of the dye, the image storability and the image fixing property.

[0050]

[Chemical 7]

In the above structural formula (1), Ar represents a substituted or unsubstituted aryl group. As the substituent, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, a carboxamide group, a sulfonyl group, a sulfamoyl group, a sulfonamide group, a ureido group, Examples thereof include a halogen group, an amino group and a heterocyclic group, and these substituents may be further substituted.

The aryl group represented by Ar above is
An aryl group having 6 to 30 carbon atoms is preferable, for example,
Phenyl group, 2-methylphenyl group, 2-chlorophenyl group, 2-methoxyphenyl group, 2-butoxyphenyl group, 2- (2-ethylhexyloxy) phenyl group, 2
-Octyloxyphenyl group, 3- (2,4-di-t-
Pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2,4,6
-Trimethylphenyl group, 3-chlorophenyl group, 3-
Methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4 -Dimethoxyphenyl group, 3- (dibutylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group,

4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group, 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group. Group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2-acetylaminophenyl group, 4-
(4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4
Examples thereof include a-(N-benzyl-N-methylamino) -2-dodecyloxycarbonylphenyl group. However, the present invention is not limited to these. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group or the like.

In the above structural formula (1), R ²¹ and R ²² are
Each independently represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. R ²¹ and R
²² may be the same or different. When substituted, examples of the substituent include an alkoxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a substituted amino group, a substituted amide group, an aryl group, an aryloxy group, and the like. However, it is not limited to these.

The alkyl group represented by R ²¹ and R ²² is preferably an alkyl group having 1 to 18 carbon atoms, and examples thereof include a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group and a butyl group. Group, sec-butyl group, t-butyl group, pentyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, t-octyl group, 2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, 4 -Methoxybenzyl group, toluphenylmethyl group, ethoxycarbonylmethyl group, butoxycarbonylmethyl group, 2-ethylhexyloxycarbonylmethyl group, 2 ', 4'-diisopentylphenyloxymethyl group, 2', 4'-di- t-butylphenyloxymethyl group, dibenzylaminocarbonylmethyl group, 2,4 Di -t- amylphenyloxy propyl group, an ethoxycarbonyl propyl group, 1-
(2 ', 4'-di-t-amylphenyloxy) propyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino)
Propyl group, methanesulfonylaminopropyl group, acetylaminoethyl group, 2- (N, N-dimethylamino)
Examples thereof include an ethyl group and a 2- (N, N-diethylamino) propyl group.

The aryl group represented by R ²¹ and R ²² is preferably an aryl group having 6 to 30 carbon atoms, and examples thereof include a phenyl group, a 2-methylphenyl group, a 2-chlorophenyl group and a 2-methoxyphenyl group. Group, 2-butoxyphenyl group, 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-
Chlorophenyl group, 2,5-dichlorophenyl group, 2,
4,6-trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group,
3-butoxyphenyl group, 3-cyanophenyl group, 3-
(2-Ethylhexyloxy) phenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,
4-dimethoxyphenyl group, 3- (dibutylaminocarbonylmethoxy) phenyl group,

4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4
-Benzylphenyl group, 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3- Acetylphenyl group, 2-acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methyl) Amino) -2-dodecyloxycarbonylphenyl group and the like. However, it is not limited to these. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group or the like.

In the above structural formula (2), R ²⁴ , R ²⁵ and R
²⁶ independently represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and R ²⁴ , R
²⁵ and R ²⁶ may be the same or different. When the substituent is substituted, for example,
Alkyl group, alkoxy group, alkylthio group, aryl group, aryloxy group, arylthio group, acyl group, alkoxycarbonyl group, carbamoyl group, carboxamide group, sulfonyl group, sulfamoyl group, sulfonamide group, ureido group, halogen atom, amino group , Heterocyclic groups and the like.

The alkyl group represented by R ²⁴ , R ²⁵ and R ²⁶ is preferably an alkyl group having 1 to 18 carbon atoms, for example, represented by R ²¹ and R ²² in the structural formula (1). And an alkyl group, a 1-methyl-2- (4-methoxyphenoxy) ethyl group, a di-n-butylaminocarbonylmethyl group, a di-n-octylaminocarbonylmethyl group, and the like.

R above^{twenty four}, R^{twenty five}And R²⁶Represented by ants
The aryl group is R in the above structural formula (1). ^{twenty one}, R^{twenty two}Represented by
It is synonymous with an aryl group. However, it is limited to these
Not of. In addition, these groups are
Group, alkylthio group, substituted phenyl group, cyano group, substituted
Substituted with amino group, halogen atom, heterocyclic group, etc.
May be.

In the above structural formula (2), Y is a hydrogen atom, OR
^And R ²³ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. When it is substituted, examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, a carboxamide group, a sulfonyl group, and a sulfamoyl group. , Sulfonamide group, ureido group, halogen atom, amino group, heterocyclic group and the like. Among the above Y, a hydrogen atom, R ²³
Is preferably an alkyloxy group in which is an alkyl group.

The alkyl group represented by R ²³ has the same meaning as the alkyl group represented by R ²¹ and R ²² in the structural formula (1). However, it is not limited to these. The aryl group represented by R ²³ is the R in the structural formula (1).
²¹ and has the same meaning as the aryl group represented by R ²² . However, it is not limited to these. Further, these aryl groups further include an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom,
It may be substituted with a heterocyclic group or the like.

In the structural formula (3), R ²⁷ and R ²⁸ are
Each independently represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and R ²⁷ and R ²⁸ may be the same or different. When it is substituted, examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, a carboxamide group, a sulfonyl group, and a sulfamoyl group. , Sulfonamide group, ureido group, halogen atom, amino group, heterocyclic group and the like.

The alkyl group represented by R ²⁷ and R ²⁸ above is
It has the same meaning as the alkyl group represented by R ²¹ and R ²² in the structural formula (1). However, it is not limited to these. The aryl group represented by R ²⁷ and R ²⁸ has the same meaning as the aryl group represented by R ²¹ and R ²² in the structural formula (1). However, it is not limited to these. Also,
These aryl groups further include an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group,
It may be substituted with a halogen atom, a heterocyclic group or the like.

In the above structural formulas (1) to (3), X ⁻
Represents an acid anion, and examples of the acid anion include polyfluoroalkylcarboxylic acid having 1 to 9 carbon atoms, polyfluoroalkylsulfonic acid having 1 to 9 carbon atoms, boron tetrafluoride, tetraphenylboron and hexafluoroline. acid,
Examples thereof include aromatic carboxylic acids and aromatic sulfonic acids.
Of these, hexafluorophosphoric acid is preferable in terms of crystallinity.

Specific examples of the diazonium salt compounds represented by the structural formulas (1) to (3) are shown below, but the invention is not limited thereto. Further, the present invention can exert its effect particularly when the diazonium salt compounds (3) -11 to (3) -16 exemplified in the following specific examples are used.

[0067]

[Chemical 8]

[0068]

[Chemical 9]

[0069]

[Chemical 10]

[0070]

[Chemical 11]

[0071]

[Chemical 12]

The diazonium salt compounds represented by the above structural formulas (1) to (3) may be used alone or in combination of two or more. Further, the diazonium salt compound represented by the structural formulas (1) to (3) may be used in combination with another existing diazonium salt compound depending on various purposes such as hue adjustment.

The coating amount of the above diazonium salt compound is preferably 0.05 to ² g / m ² in the heat-sensitive recording layer,
0.1 to 1 g / m ² is more preferable. When the content is 0.
If it is less than 05 g / m ² , a sufficient color density may not be obtained, and if it exceeds ² g / m ² , the coating suitability of the coating solution may deteriorate.

(Coupler) As the coupler for forming a dye by coupling reaction with the above-mentioned diazonium salt compound to form a color, a dye is formed by coupling with a diazonium salt compound in a basic atmosphere and / or a neutral atmosphere. Any compound can be used as long as it can.

Used in a silver halide photographic light-sensitive material,
All so-called 4-equivalent couplers can be used as couplers and can be appropriately selected within a range that matches the purpose such as hue. Examples thereof include so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives and the like.

Of these, a compound represented by the following formula (2) or a tautomer of the compound is particularly preferable. E ¹ —CH ₂ —E ² (2) In the above formula (2), E ¹ and E ² each independently represent an electron withdrawing group, and may be the same or different. The electron withdrawing group refers to a substituent having a positive Hammett σ value, and examples thereof include an acetyl group, a propionyl group, a pivaloyl group, a chloroacetyl group, a trichloroacetyl group, a trifluoroacetyl group, and 1-methylcyclopropylcarbonyl. Group, 1-ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group, thenoyl group and other acyl groups, methoxycarbonyl group, ethoxycarbonyl group, 2-methoxyethoxycarbonyl group, 4 -Alkoxycarbonyl group such as methoxyphenoxycarbonyl group, carbamoyl group, N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N-phenylcarbamoyl group, N- [2,4-bis (pentyloxy) group
Phenyl] carbamoyl group, N- [2,4-bis (octyloxy) phenyl] carbamoyl group, carbamoyl group such as morpholinocarbonyl group, methanesulfonyl group,
Alkylsulfonyl group or arylsulfonyl group such as benzenesulfonyl group, toluenesulfonyl group, phosphono group such as diethylphosphono group, benzoxazole-2
A heterocyclic group such as -yl group, benzothiazol-2-yl group, 3,4-dihydroquinazolin-4-one-2-yl group, 3,4-dihydroquinazolin-4-sulfon-2-yl group, nitro A group, an imino group and a cyano group are preferred.

The above E ¹ and E ² may combine with each other to form a ring. The ring formed by E ¹ and E ² is preferably a 5- or 6-membered carbon ring or heterocycle.

Specific examples of the above couplers include resorcin, phloroglucin, 2,3-dihydroxynaphthalene, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, and 2-hydroxy. Sodium-3-naphthalenesulfonate, 2-hydroxy-3-naphthalenesulfonic acid anilide, 2-hydroxy-3-naphthalenesulfonic acid morpholinopropylamide, 2-hydroxy-3-naphthalenesulfonic acid-2-ethylhexyloxypropylamide, 2 -Hydroxy-3-naphthalenesulfonic acid-2-ethylhexylamide, 5-acetamido-1-naphthol, 1-hydroxy-8-acetamidonaphthalene-3,6-disulfonic acid sodium salt, 1-
Hydroxy-8-acetamidonaphthalene-3,6-disulfonic acid dianilide,

1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide,
2-hydroxy-3-naphthoic acid octylamide, 2-
Hydroxy-3-naphthoic acid anilide, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclopentanedione, 5- (2-n-tetradecyloxyphenyl) -1,3-cyclohexanedione, 5 -Phenyl-4-methoxycarbonyl-1,3-cyclohexanedione, 5- (2,5-di-n-octyloxyphenyl) -1,3-cyclohexanedione, N, N'-dicyclohexylbarbituric acid, N, N'-di-n-dodecyl barbituric acid, Nn-octyl-N'-n-octadecyl barbituric acid, N-phenyl-N'-
(2,5-di-n-octyloxyphenyl) barbituric acid, N, N′-bis (octadecyloxycarbonylmethyl) barbituric acid,

1-Phenyl-3-methyl-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-anilino-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3 -Benzamide-5-pyrazolone, 6
-Hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) -2-pyridone, 2,4-bis- (benzoylacetamido) toluene, 1,3-bis- (pivaloylacetamidomethyl) benzene, Benzoylacetonitrile, thenoylacetonitrile, acetoacetanilide, benzoylacetanilide, pivaloylacetanilide, 2-chloro-5- (N-n-butylsulfamoyl) -1-pivaloylacetamidobenzene, 1-
(2-Ethylhexyloxypropyl) -3-cyano-
4-Methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (dodecyloxypropyl) -3-
Acetyl-4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (4-n-octyloxyphenyl) -3-tert-butyl-5-aminopyrazole and the like can be mentioned.

For details of the above-mentioned coupler, see Japanese Patent Application Laid-Open No. Hei 4
-201283, JP-A-7-223367, JP-A-7-223368, JP-A-7-323660, Japanese Patent Application No. 5-278608, Japanese Patent Application No. 5-297024, Japanese Patent Application No. 6-18669, Japanese Patent Application No. 6-18670, Japanese Patent Application No. 7-316280, Japanese Patent Application No. 0-027095, Japanese Patent Application No. 0-027096, Japanese Patent Application No. 08-030799,
Japanese Patent Application No. 8-12610, Japanese Patent Application No. 8-132394,
Japanese Patent Application No. 8-358755, Japanese Patent Application No. 8-358756
And Japanese Patent Application No. 9-069990.

Specific examples of the coupler represented by the above formula (2) are shown below, but the invention is not limited thereto.

[0083]

[Chemical 13]

[0084]

[Chemical 14]

[0085]

[Chemical 15]

[0086]

[Chemical 16]

The content of the coupler in the heat-sensitive recording layer is 0. 0 with respect to 1 part by mass of the diazonium salt compound.
1 to 30 parts by mass is preferable.

(Other Color-Developing Components) In the heat-sensitive recording material of the present invention, in addition to the above-mentioned diazonium salt compound and coupler (diazo-based color-forming agent) as the color-forming components, an electron-donating dye precursor and an electron-accepting compound are used. It is also possible to use a combination (leuco color former). For example, in a heat-sensitive recording material having a plurality of heat-sensitive recording layers on a support, at least one layer can be formed as a layer containing a leuco color-developing agent.

Examples of the electron-donating dye precursor include triarylmethane compounds, diphenylmethane compounds, thiazine compounds, xanthene compounds, spiropyran compounds, and the like. Triarylmethane compounds and xanthene compounds are preferred.

Specific examples include the following compounds. For example, 3,3-bis (p-dimethylaminophenyl)-
6-dimethylaminophthalide (that is, crystal violet lactone), 3,3-bis (p-dimethylamino)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(1,3-dimethylindol-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-halophenylleuco 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-cyclohexylmethylaminofluorane, 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'- Examples include dichloro-spiro-dinaphthopyran, 3-benzylspirodinaphthopyran, 3-propyl-spiro-dibenzopyran and the like.

The coating amount of the electron-donating dye precursor is preferably 0.1 to 1 g / m ² in the heat-sensitive recording layer for the same reason as in the case of the diazonium salt compound described above.

Examples of the electron-accepting compound include:
Phenol derivatives, salicylic acid derivatives, hydroxybenzoic acid esters and the like can be mentioned, with bisphenols and hydroxybenzoic acid esters being particularly preferred. Specifically, the following compounds may be mentioned. For example, 2,2-bis (p-hydroxyphenyl) propane (that is, bisphenol A), 4,4 ′-(p-phenylenediisopropylidene) diphenol (that is, 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 Polyvalent metal salt thereof, 3-α, α-dimethylbenzylsalicylic acid and polyvalent metal salt thereof, p-
Examples thereof include butyl hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol, p-cumylphenol and the like.

The content of the electron-accepting compound in the heat-sensitive recording layer is preferably 0.1 to 30 parts by mass with respect to 1 part by mass of the electron-donating dye precursor.

(Other Components) -Organic Base-In the present invention, it is preferable to add an organic base for the purpose of promoting the coupling reaction between the diazonium salt and the coupler. The organic base is preferably contained in the light and heat sensitive recording layer together with the diazonium salt and the coupler, and may be used alone or in combination of two or more kinds. Examples of the organic base include nitrogen-containing compounds such as tertiary amines, piperidines, piperazines, amidines, formamidines, pyridines, guanidines and morpholines. Also, Japanese Patent Publication No. 52-46806, Japanese Patent Laid-Open No. 62-70082, and Japanese Patent Laid-Open No. 57-16974.
5, JP-A-60-94381, JP-A-57.
-123086, Japanese Patent Laid-Open No. 58-1347901, Japanese Patent Laid-Open No. 60-49991, Japanese Patent Publication No. 2-24
Japanese Patent Publication No. 916, Japanese Patent Publication No. 28479/1990, JP-A-6
The materials described in JP-A No. 0-165288 and JP-A No. 57-185430 can also be used.

Especially, N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine, N, N '
-Bis [3- (p-methylphenoxy) -2-hydroxypropyl] piperazine, N, N'-bis [3- (p-
Methoxyphenoxy) -2-hydroxypropyl] piperazine, N, N'-bis (3-phenylthio-2-hydroxypropyl) piperazine, N, N'-bis [3-
(Β-naphthoxy) -2-hydroxypropyl] piperazine, N-3- (β-naphthoxy) -2-hydroxypropyl-N′-methylpiperazine, 1,4-bis {[3
Piperazine such as-(N-methylpiperazino) -2-hydroxy] propyloxy} benzene, N- [3- (β
-Naphthoxy) -2-hydroxy] propylmorpholine, 1,4-bis (3-morpholino-2-hydroxy-
Morpholines such as propyloxy) benzene and 1,3-bis (3-morpholino-2-hydroxy-propyloxy) benzene, piperidines such as N- (3-phenoxy-2-hydroxypropyl) piperidine and N-dodecylpiperidine , Guanidines such as triphenylguanidine, tricyclohexylguanidine, dicyclohexylphenylguanidine and the like are preferable.

When an organic base is optionally contained,
The content of the organic base in the heat-sensitive recording layer is preferably 0.1 to 30 parts by mass with respect to 1 part by mass of the diazonium salt compound.

-Sensitizer-In addition to the above organic base, a sensitizer may be added to the heat-sensitive recording layer for the purpose of accelerating the color-developing reaction. The above-mentioned sensitizer is a substance that increases the coloring density during heating recording or lowers the minimum coloring temperature, and lowers the melting point of the coupler, the organic base or the diazonium salt, or lowers the softening point of the capsule wall. By the action, the diazonium salt, the organic base, the coupler and the like are easily reacted. Specifically, a low melting point organic compound having an aromatic group and a polar group in the molecule is preferable, and for example, p
-Benzyloxybenzoic acid benzyl, α-naphthyl benzyl ether, β-naphthyl benzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p-chlorobenzyl) ether, 1 , 4-butanediol phenyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m-methylphenyl ether, 1-phenoxy Examples include 2- (p-tolyloxy) ethane, 1-phenoxy-2- (p-ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane, p-benzylbiphenyl and the like.

-Binder- Examples of the binder used in the heat-sensitive recording layer include known water-soluble polymer compounds and latexes. Examples of the water-soluble polymer compound include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivatives, casein, acacia, gelatin, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, polyvinyl. Alcohol, epichlorohydrin modified polyamide, isobutylene-maleic salicylic anhydride copolymer,
Examples thereof include polyacrylic acid, polyacrylic acid amide, and modified products thereof, and examples of the above-mentioned latexes include styrene-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion.

-Antioxidant etc.-In addition, for the purpose of improving the fastness of a colored image to light and heat, or reducing yellowing due to light of an unprinted portion (non-image portion) after fixing, the following is shown. It is also preferable to use a known antioxidant or the like. As the above-mentioned antioxidant, for example, European Published Patent No. 223739,
No. 309401, No. 309402, No. 310551, No. 310552, No. 4
59416, German Published Patent No. 3435443, JP-A-54-48535, and 62-262.
No. 047, No. 63-113536, No. 63-
No. 163351, JP-A-2-262654,
JP-A-2-71262, JP-A-3-121449
JP-A-5-611166, JP-A-5-11
9449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.

In the present invention, there are no particular restrictions on the form of use of other components such as couplers, organic bases and sensitizers. For example, (1) solid dispersion method, (2)
Emulsified and dispersed, (3) polymer dispersed and used, (4) latex dispersed and used,
(5) A method using microencapsulation and the like can be mentioned.

(Method for Producing Microcapsules) In the present invention, the above-mentioned diazonium salt (and the electron-donating dye precursor) is used in order to further improve the storage stability of the heat-sensitive recording material, particularly the raw storage stability with respect to the whiteness of the background. Body) in microcapsules. Here, in the present invention, the above-described aromatic hydrocarbon and thermal acid generator are also included.

As a method of microencapsulating the color forming component, a conventionally known method can be used. For example, an oil phase prepared by dissolving or dispersing a diazonium salt compound (and an electron-donating dye precursor), which is one of the color-forming components, in an aromatic hydrocarbon together with the above-mentioned thermal acid generator,
A water-soluble polymer is mixed with a dissolved aqueous phase, emulsified and dispersed by a means such as a homogenizer, and then heated to cause a polymer formation reaction at the oil droplet interface to form a microcapsule wall of a polymer substance. An interfacial polymerization method and the like are preferable. The interfacial polymerization method can form capsules having a uniform particle size within a short time, and a recording material excellent in raw storage stability can be obtained. Further, if necessary, another organic solvent which is sparingly soluble or insoluble in water may be used in combination with the aromatic hydrocarbon.

Examples of the other organic solvent include low boiling auxiliary solvents such as acetic acid ester, methylene chloride and cyclohexanone, and / or phosphoric acid ester, phthalic acid ester, acrylic acid ester, methacrylic acid ester and other carboxylic acid. Examples thereof include esters, fatty acid amides, chlorinated paraffins, alcohol solvents, phenol solvents, ether solvents, monoolefin solvents, epoxy solvents and the like.

Further, an antioxidant such as hindered phenol or hindered amine may be added to the above high boiling point solvent.

Examples of the water-soluble polymer include water-soluble polymers such as polyvinyl alcohol. Examples thereof include polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amino-modified polyvinyl alcohol, itaconic acid-modified polyvinyl alcohol, and styrene. -Maleic anhydride copolymer, butadiene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer,
Examples thereof include polyacrylamide, polystyrene sulfonic acid, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, gelatin and the like, and among them, carboxy-modified polyvinyl alcohol is preferable.

An emulsion or latex of a hydrophobic polymer can be used in combination with the above water-soluble polymer. Examples of the emulsion or latex include styrene-butadiene copolymer, carboxy-modified styrene-butadiene copolymer, acrylonitrile-butadiene copolymer and the like. At this time, a conventionally known surfactant or the like may be added if necessary.

Examples of the polymer substance constituting the microcapsule wall include polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin, styrene-acrylate copolymer resin,
Examples thereof include styrene-methacrylate copolymer resin, gelatin, polyvinyl alcohol and the like. Among them, polyurethane / polyurea resin is particularly preferable.

For example, when a polyurethane / polyurea resin is used as a capsule wall material, a microcapsule wall precursor such as a polyvalent isocyanate is encapsulated and mixed in an oil medium (oil phase) to be a core substance, and then the A second substance (eg, polyol, polyamine) that reacts with the capsule wall precursor to form a capsule wall is mixed in a water-soluble polymer aqueous solution (aqueous phase), and the oil phase is emulsified and dispersed in the aqueous phase, By heating, a polymer forming reaction occurs at the oil droplet interface, and the microcapsule wall can be formed.

Specific examples of the polyvalent isocyanate compound are shown below. However, it is not limited to these. For example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, 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-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate,

Diisocyanates such as cyclohexylene-1,4-diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, toluene-2,
Triisocyanates such as 4,6-triisocyanate, 4,4′-dimethylphenylmethane-2,2 ′,
Tetraisocyanates such as 5,5′-tetraisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, adducts of 2,4-tolylene diisocyanate and trimethylolpropane, xylylene diisocyanate and trimethylolpropane It is an isocyanate prepolymer such as an adduct or an adduct of tolylene diisocyanate and hexanetriol. Further, two or more kinds may be used in combination, if necessary. Among them, what is particularly preferable. It has three or more isocyanate groups in the molecule.

In the method of microencapsulation, other components such as a coupler (and an electron-accepting compound), an organic base, a sensitizer, and a microcapsule wall precursor and a second substance that reacts with the same are dissolved in an organic solvent. Is the same as the above-mentioned organic solvent. The particle size of the microcapsules is preferably 0.1 to 2.0 μm, and 0.2 to 1.5
μm is more preferable.

(Structural Mode) The specific structural mode of the multicolor thermosensitive recording material recording material will be described below. The thermosensitive recording material of the present invention is either a monochromatic thermosensitive recording material having one thermosensitive recording layer on a support, or a multicolor thermosensitive recording material having a thermosensitive recording layer having a laminated structure in which a plurality of monochromatic recording layers are laminated. May be As a multicolor thermal recording material,
A preferred embodiment is one in which at least one layer constituting the heat-sensitive recording layer is a light-fixing type recording layer containing a diazonium salt compound and a coupler that reacts with the diazonium salt compound to develop a color.

In particular, in the case of a full-color heat-sensitive recording material containing cyan, yellow and magenta, all three layers on the support are composed of diazo type color formers, or the first layer close to the support is used. A heat-sensitive recording material having a form in which the heat-sensitive recording layer is composed of a leuco color former containing an electron-donating dye and an electron-accepting compound, and the second and third heat-sensitive recording layers are composed of a diazo color former. Is preferred. For example, it may be configured in the following modes (a) to (c).

That is, (a) the maximum absorption wavelength of 3 on the support.
A photo-fixing type recording layer (first recording layer (A layer)) containing a diazonium salt compound having a wavelength of 65 ± 30 nm and a coupler which reacts with the diazonium salt compound to develop a color, and a maximum absorption wavelength of 425 ± 30 nm. A recording layer formed by laminating a photo-fixing type recording layer (second recording layer (layer B)) containing a diazonium salt compound and a coupler that reacts with the diazonium salt compound to develop a color; A heat-sensitive recording material provided with a light transmittance adjusting layer and a protective layer as necessary on the above,

(B) A recording layer containing the electron-donating dye and the electron-accepting compound on the support (first recording layer (A
Layer)), and a photo-fixing type recording layer (second recording layer (layer B)) containing a diazonium salt compound having a maximum absorption wavelength of 365 ± 30 nm and a coupler that reacts with the diazonium salt compound to develop a color. An optical fixing type recording layer (third recording layer (C layer)) containing a diazonium salt compound having a maximum absorption wavelength of 425 ± 30 nm and a coupler that reacts with the diazonium salt compound to develop a color is laminated in this order. A heat-sensitive recording material having a recording layer formed of, and optionally a light transmittance adjusting layer and a protective layer provided on the layer.

(C) On the support, the maximum absorption wavelength of 350 n
a photo-fixing recording layer (first recording layer (A layer)) containing a diazonium salt compound of m or less and a coupler that causes a color reaction with the diazonium salt compound, and a maximum absorption wavelength of 365
A photo-fixing recording layer (second recording layer (B layer)) containing a diazonium salt compound having a wavelength of ± 30 nm and a coupler which reacts with the diazonium salt compound to develop a color, and a diazonium having a maximum absorption wavelength of 425 ± 30 nm. A photo-fixing type recording layer (third recording layer (C layer)) containing a salt compound and a coupler that reacts with the diazonium salt compound to develop a color, And a heat-sensitive recording material in which a light transmittance adjusting layer and a protective layer are provided on the layer, if necessary.

The multicolor recording method will be described below with reference to (b) or (c) above. First, the third recording layer (C layer) is heated to cause the diazonium salt and the coupler contained in the layer to develop color. Next, the emission center wavelength 430 ± 3
After irradiating 0 nm light to decompose the unreacted diazonium salt compound contained in the C layer and photo-fix it, the second recording layer (B layer) is given sufficient heat to develop a color. The diazonium salt compound contained in and the coupler are colored. At this time, the C layer is also strongly heated at the same time, but the diazonium salt compound has already been decomposed (photofixed),
Does not develop color because it lacks the ability to develop color. Further, after irradiating light having an emission center wavelength of 365 ± 30 nm to decompose the diazonium salt compound contained in the B layer and fix the light, finally, sufficient heat capable of developing color in the first recording layer (A layer) is applied. In addition, color is developed. At this time, the recording layers of the C layer and the B layer are also strongly heated at the same time, but the diazonium salt compound has already been decomposed and the coloring ability is lost, so that no coloring occurs.

When all the recording layers (A layer, B layer, and C layer) are diazo type recording layers, it is necessary that the A layer and the B layer are subjected to optical fixing after color development. But,
Finally, it is not always necessary to perform optical fixing for the C layer on which image recording is performed.

The light source for fixing used for optical fixing can be appropriately selected from known light sources. For example, various fluorescent lamps,
Examples thereof include a xenon lamp and a mercury lamp. Among them, it is preferable to use a light source whose emission spectrum substantially coincides with the absorption spectrum of the diazonium chloride used for the recording material, in terms of high-efficiency optical fixing.

<Other Layers> 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 and a protective 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 above UV absorber precursor functions 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 dry coating amount of the light transmittance adjusting layer is 0.8 to
4.0 g / m ² is preferred.

(Protective Layer) The protective layer contains a binder, a pigment, a lubricant, a surfactant, a dispersant, a fluorescent whitening agent, a metal soap, a hardener, an ultraviolet absorber, a crosslinking agent and the like. . The binder is a range that does not impair the barrier property and workability, for example, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, It can be appropriately selected and used from ethylene-maleic anhydride copolymer hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylamide and the like.

In addition to the above, other binders include synthetic rubber latex and synthetic resin emulsion,
Examples thereof include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion and the like. The content of the binder is preferably 10 to 500 mass% and more preferably 50 to 400 mass% with respect to the pigment in the protective layer.

For the purpose of further improving the water resistance, it is effective to use a cross-linking agent and a catalyst for accelerating the reaction together. Examples of the cross-linking agent include epoxy compounds, blocked isocyanates and vinyl sulfone compounds. , Aldehyde compounds, methylol compounds, boric acid, carboxylic acid anhydrides, silane compounds, chelate compounds, halides, and the like, and those capable of adjusting the pH of the coating liquid for forming the protective layer to 6.0 to 7.5 are preferable. . Examples of the catalyst include known acids and metal salts, and those capable of adjusting the pH of the coating solution to 6.0 to 7.5 are preferable as in the above.

As the above-mentioned pigment, all known organic or inorganic pigments can be used. Specifically, calcium carbonate,
Aluminum hydroxide, barium sulfate, titanium oxide, talc, wax stone, kaolin, calcined kaolin, amorphous silica,
Colloidal silica, urea formalin resin powder, polyethylene resin powder, benzoguanamine resin powder and the like can be mentioned. These may be used alone or in combination of two or more. Examples of the lubricant include zinc stearate,
Preferable examples include calcium stearate, paraffin wax, polyethylene wax and the like. Suitable examples of the above-mentioned surfactant include sulfosuccinic acid-based alkali metal salts and fluorine-containing surfactants so that a protective layer can be uniformly formed on the heat-sensitive recording layer.
Examples thereof include sodium salts such as (2-ethylhexyl) sulfosuccinic acid and di- (n-hexyl) sulfosuccinic acid, and ammonium salts.

Coating liquid for forming protective layer (coating liquid for protective layer)
Is obtained by mixing the above components. Further, a release agent, wax, water repellent, etc. may be added if necessary. The heat-sensitive recording material of the present invention can be formed by coating the heat-sensitive recording layer formed on the support with the coating solution for protective layer by a known coating method. As the above-mentioned known coating method, for example,
Examples thereof include a method using a bar coater, an air knife coater, a blade coater, a curtain coater and the like. However, the protective layer may be coated simultaneously with the heat-sensitive recording layer or the light transmittance adjusting layer. For example, after coating the coating liquid for forming the heat-sensitive recording layer and drying the heat-sensitive recording layer, the protective layer is formed on the layer. It may be formed by coating.

The dry coating amount of the protective layer is 0.2 to 7
preferably ^{g / m 2, 1~4g / m} 2 is more preferable. If the dry coating amount is less than 0.2 g / m ² , water resistance may not be maintained, and if it exceeds 7 g / m ² , thermal sensitivity may be significantly reduced. After forming the coating of the protective layer,
You may give a calendar process as needed.

(Intermediate Layer) When a plurality of thermosensitive recording layers are laminated, it is preferable to provide an intermediate layer between the thermosensitive recording layers. Similar to the protective layer, the intermediate layer further contains various binders, pigments, lubricants, surfactants, dispersants, optical brighteners,
Metal soap, an ultraviolet absorber, etc. can be included. As the binder, the same binder as used for the protective layer can be used.

<Support> As the above support, for example,
Polyethylene terephthalate (PET), polyethylene naphthalate (PEN) triacetyl cellulose (TA
C), paper, plastic resin laminated paper, synthetic paper and the like. Further, in the case of obtaining a transparent heat-sensitive recording material, it is necessary to use a transparent support, and examples of the transparent support include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose triacetate film, polypropylene and the like. Examples thereof include synthetic polymer films such as polyolefin films such as polyethylene.

The above-mentioned supports can be used alone or in combination. The thickness of the synthetic polymer film is preferably 25 to 300 μm, and 100 to 2
50 μm is more preferable.

The above-mentioned synthetic polymer film may be colored in any hue, and as a method for coloring the polymer film, a method in which a dye is kneaded in advance with a resin to form a film before forming the film, and a dye is used. A method of preparing a coating solution by dissolving it in a suitable solvent and coating it on a transparent colorless resin film by a known coating method, such as a gravure coating method, a roller coating method, a wire coating method, etc., can be mentioned. Among them, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate in which a blue dye is kneaded is formed into a film, and heat-treated,
Those that have been subjected to a stretching treatment and an antistatic treatment are preferable.

The above-mentioned heat-sensitive recording layer, protective layer, light transmittance adjusting layer, intermediate layer, etc. are formed on a support by a blade coating method, an air knife coating method, a gravure coating method, a roll coating coating method, a spray coating method, a dip coating method. It can be formed by coating and drying by a known coating method such as a coating method or a bar coating method.

[0136]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Hereinafter, "parts" and "%" in the examples mean "parts by mass" and "mass%", respectively. Hereinafter, the diazonium salt compound may be simply referred to as a diazo compound.

[Example 1] (1) Preparation of coating liquid for heat-sensitive recording layer-Preparation of microcapsule liquid A containing diazo compound-The following compound A-1 (wavelength 3 as diazonium salt compound)
3.0 parts (dissolved by light of 65 nm) was dissolved in 16.4 parts of ethyl acetate, and 7.0 parts of monoisopropyl biphenyl, which is a high boiling point solvent, 2.5 parts of tricresyl phosphate, and sulfuric acid were further dissolved. 1.0 part of di (n-) butyl (thermal acid generator) was added, and heated to uniformly mix.

[0138]

[Chemical 17]

The resulting mixed liquid was added with xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution as a capsule wall material,
4.5 parts by Takeda Pharmaceutical Co., Ltd., and JP-A-7-088
The solution was added with 4.5 parts of a 30% ethyl acetate solution of a xylylene diisocyanate / bisphenol A adduct synthesized according to the description of JP-A No. 356, and further stirred uniformly to obtain a liquid I.

Separately from this, Scrap PhA G-8
77 parts of a 6% gelatin aqueous solution containing 0.96 parts (manufactured by Nippon Seika Co., Ltd.) was prepared, and the liquid I containing the diazonium salt compound was added to this and the mixture was emulsified and dispersed by a homogenizer. After adding 20 parts of water to the obtained emulsion and homogenizing it, 4
The encapsulation reaction was carried out for 3 hours while stirring at 0 ° C.
Subsequently, the liquid temperature was lowered to 35 ° C., 6.5 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corporation) and 13 parts of Amberlite IRC50 (manufactured by Organo Corporation) were added, and the mixture was further stirred for 1 hour. Then, the ion exchange resin was filtered to obtain a diazo compound-containing microcapsule liquid A. The average particle size of the microcapsules was 0.8 μm.

—Preparation of coupler emulsion B— 3.0 parts of the following coupler, 3.0 parts of triphenylguanidine, 0.5 part of tricresyl phosphate and 0.5 part of maleic acid diethyl ester were added to 10.5 parts of ethyl acetate. Two
Liquid II was obtained by dissolving 4 parts.

[0142]

[Chemical 18]

Next, a 15% aqueous solution of lime-processed gelatin 4
9 parts, 9.5 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, and 35 parts of water were uniformly mixed at 40 ° C., and the above solution II was added thereto.
The mixture was emulsified and dispersed at a temperature of 10,000 rpm for 10 minutes.
The obtained emulsion was further stirred at 40 ° C. for 2 hours to remove ethyl acetate, and then volatilized ethyl acetate and water corresponding to the mass of water were supplemented to obtain a coupler emulsion B.

-Preparation of coating liquid for thermosensitive recording layer-4.5 parts of the microcapsule liquid A obtained above and 10 parts of water
Parts and 15 parts of coupler emulsion B were uniformly mixed to prepare a coating liquid for heat-sensitive recording layer.

(2) Preparation of protective layer coating liquid (1) Itaconic acid-modified polyvinyl alcohol (KL-318,
A mixture of 100 parts of 6% aqueous solution of Kuraray Co., Ltd. and 10 parts of a dispersion liquid of 30% epoxy-modified polyamide (FL-71, manufactured by Toho Kagaku Co., Ltd.) was added to 4 parts of zinc stearate.
15 parts of 0% dispersion liquid (Hydrin Z, manufactured by Chukyo Yushi Co., Ltd.) was uniformly mixed to prepare a coating liquid (1) for protective layer.

(3) Preparation of heat-sensitive recording material A coating solution for heat-sensitive recording layer and a coating solution for protective layer (1) were applied in this order on a support for printing paper obtained by laminating polyethylene on high-quality paper in this order, It was dried at 50 ° C. to prepare a thermal recording material (1) of the present invention. The coating amount (solid content) of the thermal recording layer coating liquid and the protective layer coating liquid (1) is
Each 9.0 g / m ^2, was 1.2 g / m ^2.

Examples 2 to 4 Di (n-) butyl sulfate (thermal acid generator) used in the preparation of the diazo compound-containing microcapsule solution A of Example 1 was mixed with di (n-) propyl sulfate and p -The heat-sensitive recording material (2) of the present invention in the same manner as in Example 1 except that methyltoluenesulfonate and ethyl p-toluenesulfonate (above, thermal acid generator) were used instead.
(4) was produced.

Example 5 The same as Example 1 except that diisopropylnaphthalene (aromatic hydrocarbon) was used in place of monoisopropylbiphenyl used in the preparation of the diazo compound-containing microcapsule solution A of Example 1. Then, a thermal recording material (5) of the present invention was produced.

[Comparative Example 1] A comparative example was carried out in the same manner as in Example 1 except that tricresyl phosphate was used instead of monoisopropylbiphenyl used in the preparation of the diazo compound-containing microcapsule solution A of Example 1. A heat-sensitive recording material (6) was prepared.

[Comparative Example 2] The same procedure as in Example 1 was repeated except that the di (n-) butyl sulfate (thermal acid generator) used in the preparation of the diazo compound-containing microcapsule solution A of Example 1 was not used. Thus, a thermal recording material (7) of Comparative Example was produced.

[Evaluation 1] The following conditions (1-1) and (1-2) were applied to the heat-sensitive recording materials (1) to (5) and the heat-sensitive recording materials (6) to (7) obtained above. According to the above, the density of the image area and the non-image area (background density; yellow coloring) was evaluated. The measurement results are shown in Table 1 below.

(1-1) A thermal head KST type (manufactured by Kyocera Corp.) was prepared, and the applied power and pulse width to the thermal head were adjusted so that the printing energy per unit area was 40 mJ / mm ² . Thereafter, each of the heat-sensitive recording materials was heat-printed to record a yellow image. afterwards,
The heat-sensitive recording material was irradiated with an ultraviolet ray lamp having an emission center wavelength of 365 nm and an output of 40 W for 10 seconds for optical fixing. Thereafter, the optical reflection yellow densities of the color-developed portion and the background portion of the obtained image were measured with an X-rite densitometer after 10 minutes of optical fixing.

(1-2) Replace each of the unrecorded thermal recording materials with 6
After left for 72 hours in a high temperature and humidity chamber adjusted to an environmental condition of 0 ° C. and 30% RH for forced deterioration treatment, the above (1-
Optically fix under the same conditions as in the case of 1), and then use the X-rite densitometer to measure the optical reflection yellow density of the background portion by optical fixation.
Measured after a minute.

[0154]

[Table 1]

As shown in Table 1 above, in the thermosensitive recording materials (1) to (5) in which the diazonium salt compound was encapsulated in the microcapsules together with the aromatic hydrocarbon and the thermal acid generator, the color density of the image area was changed. It was possible to reduce the background density (yellow coloring) without deteriorating, and to form an image with excellent whiteness and high contrast. Moreover, there was no significant increase in the background density due to the forced deterioration treatment, and good storage stability (raw storage stability) was exhibited with respect to the whiteness of the background. On the other hand, in the heat-sensitive recording material (6) or (7) of Comparative Example in which neither aromatic hydrocarbon nor a thermal acid generator was used,
Since the background density is high and the whiteness is inferior, it is not possible to obtain a high-contrast image, and the background density is remarkably increased due to the forced deterioration treatment, and sufficient storage stability (raw storage stability) cannot be obtained. .

[Example 6] <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 thermosensitive recording layer liquid <diazonium salt compound-encapsulating microcapsule liquid (a)
Preparation of> In 16.1 parts of ethyl acetate, 2.2 parts of the following diazonium compound (A) (maximum absorption wavelength 420 nm) and the following diazonium compound (B) (maximum absorption wavelength 420 nm)
2.2 parts, monoisopropyl biphenyl 3.8 parts, di (n-) butyl sulfate 1.0 part, and diphenyl- (2,
4,6-Trimethylbenzoyl) phosphine oxide (trade 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. ) 8.6 parts were added, and the mixture was stirred uniformly to obtain a mixed solution (I).

Separately, the above phthalated gelatin aqueous solution 58.
6 parts of ion-exchanged water 16.3 parts, Scratch AG-
8 (50%; Nippon Seika Co., Ltd.) 0.17 part 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.

[0160]

[Chemical 19]

<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.)
12.0 parts, 4,4 '-(m-phenylene diisopropylidene) 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 above 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, 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 to 100 parts of the coupler compound emulsion. And uniformly stirred to obtain a coupler compound emulsion (a).

[0163]

[Chemical 20]

<Preparation of coating liquid (a)> The mass ratio of coupler compound / diazo compound in which the above-mentioned microcapsule liquid containing a diazonium salt compound (a) and the above-mentioned coupler compound emulsion (a) 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 thermosensitive recording layer liquid <diazonium salt compound-containing microcapsule liquid (b)
Preparation of> In 12.8 parts of ethyl acetate, 3.8 parts of the following diazonium compound (D) (maximum absorption wavelength 365 nm), 7.6 parts of monoisopropyl biphenyl, 2.0 parts of tricresyl phosphate, di (n-) sulfate. 1.1 parts of butyl and calcium dodecylbenzene sulfonate (trade name: Pionine A-41-C 70% methanol solution, Takemoto Yushi Co., Ltd.)
(Manufactured by Mitsui Chemical Co., Ltd.) 0.15 part was added and heated to uniformly dissolve.
10.9 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.)) was added to the mixed solution as a capsule wall material and stirred uniformly. A mixed solution (V) was obtained.

Separately, the phthalated gelatin aqueous solution 59.
Ion-exchanged water 22.8 parts, sodium dodecylbenzenesulfonate 25% aqueous solution (trade name; Neoperex F-25, manufactured by Kao Co., Ltd.) 0.31 parts were added to 9 parts and mixed, and the mixed solution (VI) was added. Obtained. The mixed solution (V) was added to the mixed solution (VI), and the mixture was emulsified and dispersed at 30 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). Water 2 in the obtained emulsion
After adding 7.3 parts and homogenizing, the mixture was stirred at 40 ° C. and the encapsulation reaction was carried out for 2 hours while removing ethyl acetate. After that, 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industry Co., Ltd.)
0.27 parts was added. Then, 3.9 parts of ion exchange resin Amberlite IRA67 (manufactured by Organo Corporation), S
Add 7.8 parts of WA100-HG (manufactured by Organo Corporation),
It was stirred for another 1.5 hours. Then, the ion exchange resin was removed by filtration, and the solid content concentration of the capsule liquid was 18.5.
The concentration was adjusted to be 100% to obtain a diazonium salt compound-encapsulating microcapsule liquid (b). 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 0.55 μm.

[0167]

[Chemical 21]

<Preparation of coupler compound emulsion (b)> The following coupler compound (E) 6.3 was added to 36.9 parts of ethyl acetate.
And triphenylguanidine (Hodogaya Chemical Co., Ltd.)
14.0 parts, 4,4 '-(m-phenylenediisopropylidene) diphenol (trade name; bisphenol M (manufactured by Mitsui Petrochemical Co., Ltd.)) 14.0 parts, 1,1- (p-hydroxyphenyl) ) -2-Ethylhexane 14 parts, 3,
3,3 ', 3'-tetramethyl-5,5', 6,6'-
Tetra (1-propoxy) -1,1′-spirobisindane 3.5 parts, the following compound (G) 3.5 parts, tricresyl phosphate 1.7 parts, diethyl maleate 0.8 parts, dodecylbenzene sulfonic acid 4.5 parts of calcium (trade name: Pionin A-41-C, 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) was 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 resulting coupler compound emulsion was measured by a particle size measurement (LA-700, manufactured by Horiba Ltd.), and the median size was 0.23 μm.
It was m.

[0170]

[Chemical formula 22]

<Preparation of coating liquid (b)> The mass ratio of coupler compound / diazo compound encapsulating the microcapsule liquid (b) containing the diazonium salt compound and the emulsion emulsion (b) of the coupler compound is 1. Mixed to be 9/1. Further, a polystyrene sulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) was added to the capsule liquid volume 10
The mixture was mixed so as to be 0.015 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., 8.0 parts, and the following compound (I) (trade name; Irgaperm 2140 manufactured by Ciba-Geigy Co., Ltd.) 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, with respect to 100 parts of the above microcapsule liquid, a 25% sodium dodecylbenzenesulfonate aqueous solution (trade name; Neoperex F-25, manufactured by Kao Corporation)
Fluorescent brightener containing 3.7 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).

[0174]

[Chemical formula 23]

<Preparation of Electron-Accepting Compound Dispersion (c)>
To 11.3 parts of the phthalated gelatin aqueous solution described above, 30.1 parts of ion-exchanged water and 15 parts of 4,4 '-(p-phenylenediisopropylidene) diphenol (trade name; bisphenol P, manufactured by Mitsui Petrochemical Co., Ltd.) A 2% aqueous solution of sodium 2-ethylhexylsuccinate (3.8 parts) was added, and the mixture was dispersed overnight in a ball mill to obtain a dispersion liquid. The solid content concentration of this dispersion was 26.6%. Dispersion 10
41.0 parts of the above alkali-treated gelatin aqueous solution was added to 0 parts and stirred for 30 minutes, after which the solid content concentration of the dispersion was 23.
Ion-exchanged water was added so as to be 5% to obtain an electron-accepting compound dispersion liquid (c).

<Preparation of coating liquid (c)> The above-mentioned microcapsule liquid (c) containing an electron-donating dye precursor in the interior 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.) 2.857 parts, calcium hydroxide 0.5 part, 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.

Gelatin aqueous solution 10.0 for preparing the above 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, and the following compound (J) 4
% Aqueous solution 3.42 parts, a 4% aqueous solution of the following compound (J ′) 1.13 parts, and ion-exchanged water 0.67 parts were mixed to obtain a coating solution for the intermediate layer.

[0179]

[Chemical formula 24]

(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,
Tricresyl phosphate 4.3 parts, α-methylstyrene dimer (trade name: MSD-100, manufactured by Mitsui Chemicals, Inc.) 4.
3 parts and 0.45 part of calcium dodecylbenzenesulfonate (trade name: Pionine A-41-C (70% methanol solution), manufactured by Takemoto Yushi Co., Ltd.) were dissolved and uniformly dissolved.
54.7 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), 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% aqueous phosphoric acid 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 above 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. To this capsule liquid (859.1 parts) was mixed carboxy-modified styrene-butadiene latex (trade name: SN-307 (48% aqueous solution), manufactured by Sumitomo Nogatak Co., Ltd.) 2.416 parts, and ion-exchanged water 39.5 parts, An ultraviolet absorber precursor microcapsule liquid was obtained.

<Preparation of coating liquid for light transmittance adjusting layer> 1000 parts of the above-mentioned UV absorber precursor microcapsule liquid, a fluorine-containing 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 Co., Ltd. )
(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 for Protective Layer> Barium sulfate (trade name: BF-21F, barium sulfate content 93%)
As mentioned above, anionic special polycarboxylic acid type polymer activator (trade name: Poise 532A) is added to 8 parts of Sakai Chemical Industry Co., Ltd.
(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 above barium sulfate dispersion liquid, colloidal silica (trade name:
Snowtex O (20% aqueous dispersion), Nissan Chemical Co., Ltd.
(Manufactured by K.K.) 10.2 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 above polyvinyl alcohol solution for 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, 49.87 parts of the pigment dispersion for the protective layer, 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 6 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 above mica dispersion liquid 20.
8 parts were added and mixed thoroughly with stirring, and 9.8 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, a polyethylene resin containing 10% of anatase type titanium dioxide and a trace amount of ultramarine blue was coated on the side opposite to the surface on which the above resin layer was formed so as to have a resin thickness of 50 μm, and a resin having a glossy surface was formed. A layer was formed (this side is referred to as the "front side"). Corona discharge treatment was applied to the polyethylene resin coated surface on the back side, and then aluminum oxide (trade name; alumina sol 10
0, manufactured by Nissan Chemical Industry Co., Ltd./silicon dioxide (trade name; Snowtex O, manufactured by Nissan Chemical Industry Co., Ltd.) = 1/2 (mass ratio) is dispersed in water and the mass after drying is 0. 2 g / m ²
Applied. Next, after subjecting the polyethylene resin-coated surface of the front surface to corona discharge treatment, the above-mentioned coating solution for the undercoat layer was applied so that the coating amount of mica was 0.20 g / m ² to obtain a support with an undercoat layer. It was

<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), The coating solution for the thermosensitive recording layer (b), the coating solution for the intermediate layer (intermediate layer B), the coating solution for the thermal recording layer (a), the coating solution for the light transmittance adjusting layer, the 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.
Multicolor thermosensitive recording material (8) which is dried under the condition of 0%
Got At this time, the coating amount of the coating liquid (a) for the thermosensitive 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 the solid coating amount, and 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 recording layer coating liquid (c) was adjusted so that the coating amount of the electron-donating dye (H) contained in the liquid was 0.355 g / m ^{2 in} terms of solid content coating amount. .

The coating liquid for the intermediate layer B has a solid content coating amount of 2.39 g / m ² , the coating liquid for the intermediate layer A has a solid content coating amount of 3.34 g / m ² , and the light transmittance is adjusted. 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 1.80 g / m ² .

Example 7 In place of the di (n-) butyl sulfate (thermal acid generator) used in the magenta thermosensitive recording layer coating solution and the yellow thermosensitive recording layer coating solution prepared in Example 6, p
-A multicolor thermosensitive recording material (9) of the present invention was prepared in the same manner as in Example 6 except that methyl toluenesulfonate (thermal acid generator) was used.

Comparative Example 3 The di (n-) butyl sulfate (thermal acid generator) used in the preparation of the magenta thermosensitive recording layer coating solution and the yellow thermosensitive recording layer coating solution in Example 6 was not added. A multicolor heat-sensitive recording material (10) of a comparative example was produced in the same manner as in Example 6 except for the above.

[Evaluation 2] A thermal head KST type (manufactured by Kyocera Corp.) was used for each of the multicolor thermosensitive recording materials (8) to (9) and the thermosensitive recording material (10) obtained as described above. According to (2-1) to (2-3), the densities of the image area and the non-image area (background density; yellow coloring) were evaluated. The measurement results are shown in Table 2 below.

(2-1) After adjusting the electric power applied to the thermal head and the pulse width so that the printing energy per unit area was 35 mJ / mm ² , a yellow image was recorded by thermal printing on each thermal recording material. did. afterwards,
Multicolor thermosensitive recording material with emission center wavelength of 420 nm, output of 40
Irradiation was performed for 10 seconds using a W ultraviolet lamp to perform optical fixing.

(2-2) Similarly to the above, a magenta image was recorded by printing so that the printing energy per unit area was 80 mJ / mm ² . Then, the heat-sensitive recording material was irradiated with an ultraviolet ray lamp having an emission center wavelength of 365 nm and an output of 40 W for 10 seconds for optical fixing.

(2-3) Further, a cyan image was recorded by printing so that the printing energy per unit area was 140 mJ / mm ² . The optical reflection yellow densities of the color-developed portion, the background portion, and the background portion after forced deterioration of the image obtained above were measured with an X-rite densitometer after 10 minutes of optical fixing. The measurement results are shown in Table 2 below. The conditions for forced deterioration are the same as in (1-2) above.

[0200]

[Table 2]

As shown in Table 2 above, in the thermosensitive recording materials (8) to (9) in which the diazonium salt compound was encapsulated in the microcapsules together with the aromatic hydrocarbon and the thermal acid generator, the coloring density of each color was impaired. Without this, the background density (yellow) can be reduced, the background whiteness is excellent, and a high-contrast and clear full-color image can be formed. Moreover, there was no significant increase in the background density due to the forced deterioration treatment, and good storage stability (raw storage stability) was exhibited with respect to the whiteness of the background. On the other hand, in the heat-sensitive recording material (10) of Comparative Example in which the thermal acid generator was not used in combination, the background density was high and the whiteness was inferior, a clear full-color image was not obtained, and the background density was increased by the forced deterioration treatment. However, it was not possible to obtain sufficient storage stability (raw preservation).

[0202]

According to the present invention, the whiteness of the non-image part (background part) and the storage stability (raw storage property) against the whiteness are particularly excellent, and the color density of the image part is not impaired.
It is possible to provide a heat-sensitive recording material capable of stably forming a clear image with high contrast.

Claims (2)

[Claims] 1. A thermosensitive recording material having a thermosensitive recording layer on a support, the thermosensitive recording layer containing at least a diazonium salt compound and a coupler for producing a color by a coupling reaction with the diazonium salt compound, wherein the diazonium salt compound is an aromatic compound. A heat-sensitive recording material, which is encapsulated in microcapsules together with a hydrocarbon and a thermal acid generator. 2. The thermal acid generator is at least one selected from an arylalkylsulfonyl compound represented by the following general formula (I) and a sulfuric acid dialkyl ester compound represented by the following general formula (II). The heat-sensitive recording material according to claim 1. [Chemical 1] [In general formula (I), Ar represents an aryl group, and R represents an alkyl group, a cycloalkyl group, or an aralkyl group. ] [Chemical 2] [In general formula (II), R'represents an alkyl group having 24 or less carbon atoms and a cycloalkyl group having 24 or less carbon atoms. ]