JP2006102957A - Thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording material which has excellent coloring properties and therefore, can produce a desired coloring density in a short time, during printing. <P>SOLUTION: This thermal recording material has a recording layer, formed on a support, containing a non-dissociation-type coupler and a diazonium salt compound, expressed by formula (1), which is encapsulated in a microcapsule, In addition, the ratio of an increase in the coloring density 600 sec after printing to an increase in the coloring density 6 sec after printing, is not more than 10%. In this formula (1), Ar is an aryl group and X<SP>-</SP>is anion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material using a combination of a diazonium salt compound and a non-dissociative coupler as a color forming component.

  The diazonium salt compound reacts with a coupling component such as a phenol derivative or a compound having an active methylene group to form an azo dye. Further, the diazonium salt compound has a property of decomposing by light irradiation and losing its activity. Conventionally, a diazonium salt compound has been used for a long time as an optical recording material typified by diazocopy by utilizing this property (see, for example, Non-Patent Document 1).

  In addition, diazonium salt compounds have recently been applied to recording materials that require image fixing. As a typical example, a diazonium salt compound and a coupler compound are heated according to an image signal and reacted to form an image. Then, there has been proposed a light-fixing type heat-sensitive recording material in which an image is fixed by irradiation with light (see, for example, Non-Patent Document 2).

In the photo-fixing type heat-sensitive recording material, a non-dissociation type coupler may be used as the coupler. However, in the case of a heat-sensitive recording material using a non-dissociative coupler, high color developability cannot be obtained, and as a result, the dyeing reaction is not completed between printing and fixing, and the desired color density cannot be obtained. There was a problem.
Japan Photographic Society, "Basics of Photographic Engineering-Non-Silver Salt Photography", Corona, 1982, pp. 89-117, 182-201 Koji Sato, “Journal of the Institute of Image Electronics Engineers,” Volume 11, Issue 4, 1982, 290-296

  An object of the present invention is to provide a heat-sensitive recording material excellent in color developability, which can obtain a desired color density in a short time during printing.

The above-mentioned subject is achieved by the following invention.
That is, in the present invention, first, the first invention is
<1> A thermosensitive recording material having a recording layer comprising a non-dissociative coupler on a support and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, after printing The heat-sensitive recording material is characterized in that the color density increase rate after 600 seconds after printing is 10% or less with respect to the color density after 6 seconds.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ]

In addition, the second invention,
<2> A heat-sensitive recording material having a recording layer comprising a non-dissociative coupler on a support and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, The thermosensitive recording material is characterized in that the I / O value of the Ar portion of the diazonium salt compound represented by the formula (1) is 0.50 or less.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ]

  <3> The heat-sensitive recording material according to <2>, wherein the diazonium salt compound represented by the general formula (1) is represented by the following general formula (2) or (3).

[In the general formula (2), R ²¹ represents a hydrogen atom, an alkyl group, or an aryl group. R ²² represents an alkyl group or an aryl group. R ²³ , R ²⁴ , R ²⁵ and R ²⁶ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ²³ , R ²⁴ , R ²⁵ and R ²⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion. ]

[In the general formula (3), R ¹ and R ² each independently represents an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group or a carbamoyl group, and R ¹ and R ² are bonded to each other to form a ring. It may be formed. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, halogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group or -N ₂ ⁺ X ^- represents a. However, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion. ]

  According to the present invention, it is possible to provide a heat-sensitive recording material excellent in color developability that can obtain a desired color density in a short time during printing.

≪First thermal recording material≫
The first heat-sensitive recording material in the present invention (refers to the heat-sensitive recording material described in claim 1 and may be simply referred to as “first invention” in the present specification) is not on the support. A thermal recording material having a recording layer comprising a dissociative coupler and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, wherein the printing is performed for a color density 6 seconds after printing. The increase in color density after 600 seconds is 10% or less.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ]

The increase rate of the color density is preferably as low as possible. However, from the viewpoint of obtaining a desired color density in a short time, it is required to be 10% or less as described above, and desirably 8% or less. Furthermore, it is desirable that it is 6% or less.
Here, “after printing” refers to the state after the point when energy of 40 mJ / mm ² or more is applied to the heat-sensitive recording material by a thermal head for several tens of msec, and the same applies hereinafter.

  The increasing ratio of the color density was calculated from both densities measured by X-Rite 310RD (manufactured by Nihon Himeki Equipment Co., Ltd.) after 6 seconds and 600 seconds after printing.

≪Second thermal recording material≫
Further, the second heat-sensitive recording material in the present invention (refers to the heat-sensitive recording material described in claim 2 and may be simply referred to as “second invention” in this specification) is provided on the support. A thermosensitive recording material comprising a non-dissociative coupler and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, which is represented by the general formula (1): The I / O value of the Ar portion of the diazonium salt compound (when the aryl group represented by Ar includes a substituent, the substituent is also included) is 0.50 or less.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ]

  By using a diazonium salt compound having an Ar portion I / O value of 0.50 or less in a heat-sensitive recording material using a non-dissociative coupler, a desired color density can be obtained in a short time during printing. Further, the first aspect of the present invention is such that the increasing ratio of the color density after 600 seconds after printing is 10% or less with respect to the color density after 6 seconds after printing. A heat-sensitive recording material can be obtained.

  The I / O value is further preferably 0.48 or less, particularly preferably 0.45 or less. From the viewpoint of reducing the reactivity of the diazonium salt compound, the I / O value is preferably 0.20 or more.

  Here, in the present invention, the I / O value is a value calculated according to the method described in “Organic Conceptual Diagram—Basics and Applications—” (Yoshio Koda, Sankyo Publishing, May 10, 1984, p11-22). And

  Hereinafter, each layer constituting the first heat-sensitive recording material and the second heat-sensitive recording material (hereinafter referred to simply as “the heat-sensitive recording material of the present invention”) will be described in more detail. .

<Recording layer>
The heat-sensitive recording material of the present invention has a recording layer containing a non-dissociative coupler and a diazonium salt compound encapsulated in microcapsules on a support. The recording layer may contain various additives such as a color forming aid, if necessary.

(Diazonium salt compound)
The heat-sensitive recording material of the present invention contains the diazonium salt compound represented by the general formula (1) encapsulated in the microcapsule in the recording layer, and in the second invention, as described above, the diazonium salt compound The I / O value of the Ar portion of the salt compound is required to be 0.50 or less.

  As the diazonium salt compound represented by the general formula (1), a diazonium salt compound represented by the following general formula (2) or general formula (3) is used from the viewpoint of obtaining an appropriate I / O value. It is preferable.

  -Compound represented by the general formula (2)-

In general formula (2), R ²¹ represents a hydrogen atom, an alkyl group or an aryl group. R ²² represents an alkyl group or an aryl group. R ²³ , R ²⁴ , R ²⁵ and R ²⁶ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ²³ , R ²⁴ , R ²⁵ and R ²⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion.
The above -N ₂ ⁺ represents a diazonio group.

The alkyl group represented by R ²¹ may be unsubstituted or substituted, and examples of the substituent introduced into the alkyl group include an aryl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxyl group, a sulfonyl group, and a heterocyclic residue are preferable.
The alkyl group represented by R ²¹ is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 20 carbon atoms. Specifically, methyl group, ethyl group, butyl group, hexyl group, octyl group, 2-ethylhexyl group, 3,5,5-trimethylhexyl group, dodecyl group, octadecyl group, benzyl group, (4-ethoxyphenyl) Methyl group, N, N-diethylcarbamoylmethyl group, N, N-dibutylcarbamoylmethyl group, 1- (N, N-dibutylcarbamoyl) ethyl group, 2-methoxyethyl group, 1-methyl-2-phenoxyethyl group, (4-Chlorophenyl) methyl group and (2,4-dichlorophenyl) methyl group are preferred, ethyl group, butyl group, hexyl group, benzyl group, N, N-diethylcarbamoylmethyl group, N, N-dibutylcarbamoylmethyl group 1- (N, N-dibutylcarbamoyl) ethyl group, 1-methyl-2-phenoxyethyl group, (4- Rorofeniru) methyl group, (2,4-dichlorophenyl) methyl group is particularly preferred.

The aryl group represented by R ²¹ may be unsubstituted or substituted, and examples of the substituent introduced into the aryl group include an alkyl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxyl group, a sulfonyl group, and a heterocyclic residue are preferable.
The aryl group represented by R ²¹ is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 20 carbon atoms. Specifically, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-phenylphenoxy group, 4-chlorophenyl group, 2-methoxyphenyl group, 3-ethoxyphenyl group, 4 -Butoxyphenyl group, 2,4-diethoxyphenyl group, 2,5-dibutoxyphenyl group, 4-phenoxyphenyl group, naphthyl group, 4-dibutylcarbamoylphenyl group, 4-dibutylsulfamoylphenyl group are preferred, A phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-chlorophenyl group, 2-methoxyphenyl group, 3-ethoxyphenyl group, and 4-butoxyphenyl group are particularly preferable.

The alkyl group and aryl group represented by R ²² have the same meanings as the alkyl group and aryl group represented by R ²¹ , and preferred specific examples thereof are also the same.

Examples of the monovalent substituent represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ include an alkyl group, an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, and an alkoxy group. A carbonyl group, a carbamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, and —N ₂ ⁺ X ⁻ are preferred, and further a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group A group, an acylamino group, a sulfamoyl group, or —N ₂ ⁺ X ⁻ , but as described above, at least one of R ²³ , R ²⁴ , R ^25, and R ²⁶ represents —N ₂ ⁺ X ⁻ .

The alkyl group and aryl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ have the same meaning as in R ²¹ , and preferred specific examples are also the same.

The halogen atom represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, more preferably a fluorine atom or a chlorine atom.

The alkoxy group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an alkoxy group having 1 to 30 carbon atoms in total, having 1 carbon atom in total. More preferred are ˜20 alkoxy groups. Specifically, for example, methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, 2-ethylhexyloxy group, 3,5,5-trimethylhexyloxy group, octyloxy group, decyloxy group, 2-phenoxy An ethoxy group, 2- (3,5-di-t-butylphenoxy) ethoxy group, dibutylcarbamoylmethoxy group, hexadecyloxy group, and octadecyloxy group are preferable, methoxy group, ethoxy group, butoxy group, hexyloxy group, 2 -Ethylhexyloxy group, 3,5,5-trimethylhexyloxy group, 2-phenoxyethoxy group, and dibutylcarbamoylmethoxy group are more preferable.

The aryloxy group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an aryloxy group having 6 to 30 carbon atoms in total. An aryloxy group having a number of 6 to 20 is more preferable. Specifically, for example, phenoxy group, tolyloxy group, 4-chlorophenyloxy group, 4-acetamidophenyloxy group, 2-butoxyphenyloxy group, 2-benzoylaminophenyloxy group, 2,5-dimethoxy-4-nitro Phenyloxy group and 3-octyloxyphenyloxy group are preferable, phenoxy group, tolyloxy group, 4-chlorophenyloxy group, 4-acetamidophenyloxy group, 2-butoxyphenyloxy group, 2,5-dimethoxy-4-nitrophenyl An oxy group is more preferable.

The alkylthio group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an alkylthio group having 1 to 30 carbon atoms, More preferred are 20 alkylthio groups. Specifically, for example, methylthio group, ethylthio group, butylthio group, hexylthio group, 2-ethylhexylthio group, 3,5,5-trimethylhexylthio group, octylthio group, decylthio group, 2-phenoxyethylthio group, 2 -(3,5-di-t-butylphenoxy) ethylthio group, dibutylcarbamoylmethylthio group, hexadecylthio group, octadecylthio group are preferred, methylthio group, ethylthio group, butylthio group, hexylthio group, 2-ethylhexylthio group, 3, More preferred are 5,5-trimethylhexylthio group, 2-phenoxyethylthio group, and dibutylcarbamoylmethylthio group.

The arylthio group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an arylthio group having 6 to 30 carbon atoms in total, having 6 carbon atoms in total. More preferred are ˜20 arylthio groups. Specifically, for example, phenylthio group, tolylthio group, 4-chlorophenylthio group, 4-acetamidophenylthio group, 2-butoxyphenylthio group, 2-benzoylaminophenylthio group, 2,5-dimethoxy-4-nitro Phenylthio group and 3-octyloxyphenylthio group are preferable, phenylthio group, tolylthio group, 4-chlorophenylthio group, 4-acetamidophenylthio group, 2-butoxyphenylthio group, 2,5-dimethoxy-4-nitrophenyl More preferred is a thio group.

The acylamino group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an acylamino group having 1 to 30 carbon atoms in total. More preferred is an acylamino group of ˜20. Specifically, for example, formylamino group, acetylamino group, butyrylamino group, lauroylamino group, benzoylamino group, toluoylamino group, phenoxyacetyl group, (4-methoxyphenoxy) acetyl group, 2 ′, 4 ′ -Dichlorobenzoylamino group, 2 ', 4'-di-t-amylbenzoylamino group, acetylmethylamino group, benzoylmethylamino group, acetylbenzylamino group are preferred, acetylamino group, butyrylamino group, benzoylamino group, toluene More preferred are an oilamino group, a phenoxyacetyl group, a 2 ′, 4′-di-t-amylbenzoylamino group, an acetylmethylamino group, a benzoylmethylamino group, and an acetylbenzylamino group.

The alkoxycarbonyl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an alkoxycarbonyl group having 2 to 30 carbon atoms in total. A C2-C20 alkoxycarbonyl group is more preferable. Specifically, for example, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, phenoxycarbonyl group, (2-ethylhexyl) oxycarbonyl group, hexyloxycarbonyl group, octyloxycarbonyl group, (4-methoxyphenyl) oxycarbonyl Group is preferable, and methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group are particularly preferable.

The carbamoyl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably a carbamoyl group having 1 to 30 carbon atoms in total. More preferred are -20 carbamoyl groups. Specifically, for example, carbamoyl group, N-phenylcarbamoyl group, N-butylcarbamoyl group, N-octylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N, N-dibutylcarbamoyl Group, N, N-dihexylcarbamoyl group, N, N-diphenylcarbamoyl group, N-methyl-N-phenylcarbamoyl group, N-ethyl-N-phenylcarbamoyl group, N-methyl-N-tolylcarbamoyl group, morpholinocarbonyl Group, piperidinocarbonyl group and N, N-bis (2-methoxyethyl) carbamoyl group are preferable, N-butylcarbamoyl group, N-octylcarbamoyl group, N-phenylcarbamoyl group, N, N-diethylcarbamoyl group, N, N-dibutylcarbamoyl group, N-methyl- - phenylcarbamoyl group is particularly preferred.

The alkylsulfonyl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an alkylsulfonyl group having 1 to 30 carbon atoms in total. A C1-C20 alkylsulfonyl group is more preferable. Specifically, for example, a methylsulfonyl group, an ethylsulfonyl group, a butylsulfonyl group, a hexylsulfonyl group, and a benzylsulfonyl group are preferable, and a methylsulfonyl group and a benzylsulfonyl group are particularly preferable.

The arylsulfonyl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably an arylsulfonyl group having 6 to 30 carbon atoms in total. An arylsulfonyl group having a number of 6 to 20 is more preferable. Specifically, for example, a phenylsulfonyl group, a 4-methylphenylsulfonyl group, a naphthylsulfonyl group, a 4-methoxysulfonyl group, and a 4-chlorophenylsulfonyl group are preferable, and a phenylsulfonyl group and a 4-methylphenylsulfonyl group are particularly preferable.

The sulfamoyl group represented by R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be unsubstituted or substituted, and is preferably a sulfamoyl group having 0 to 30 carbon atoms in total, having 0 carbon atoms in total. More preferred are ˜20 sulfamoyl groups. Specifically, for example, sulfamoyl group, N-phenylsulfamoyl group, N, N-dimethylsulfamoyl group, N, N-diethylsulfamoyl group, N, N-dibutylsulfamoyl group, N, N-dihexylsulfamoyl group, N, N-diphenylsulfamoyl group, N-methyl-N-phenylsulfamoyl group, N-ethyl-N-phenylsulfamoyl group, N-methyl-N-tolylsulfur group Famoyl group, morpholinosulfonyl group, piperidinosulfonyl group, N, N-bis (2-methoxyethyl) sulfonyl group are preferable, sulfamoyl group, N-phenylsulfamoyl group, N, N-dibutylsulfamoyl group N, N-diphenylsulfamoyl group and N-methyl-N-phenylsulfamoyl group are particularly preferable.

In the general formula (2), it is preferable that at least one of R ²³ , R ²⁴ , R ²⁵ and R ²⁶ is an alkoxyl group or an aryloxy group. This alkoxyl group and aryloxy group are synonymous with the above-mentioned alkoxyl group and aryloxy group, and preferred examples are also the same. In addition, as a substitution position, R ²⁴ is particularly preferably an alkoxy group or an aryloxy group.

In addition, at least one of R ²³ , R ²⁴ , R ²⁵ and R ²⁶ represents —N ₂ ⁺ X ⁻ , but R ²⁵ is particularly preferably —N ₂ ⁺ X ⁻ .

The anion represented by X ⁻ may be either an inorganic anion or an organic anion. As the inorganic anion, for example, hexafluorophosphate ion, borohydrofluoric acid ion, chloride ion, and sulfate ion are preferable, and hexafluorophosphate ion and borohydrofluoric acid ion are particularly preferable. Further, as the organic anion, for example, polyfluoroalkylcarboxylate ions, polyfluoroalkylsulfonate ions, aromatic carboxylate ions, aromatic sulfonate ions, and ions described in Japanese Patent Application No. 2002-108919 are preferable. Among these, polyfluoroalkylcarboxylate ions, polyfluoroalkylsulfonate ions, and ions described in Japanese Patent Application No. 2002-108919 are particularly preferable.

Further, as the diazonium salt compound represented by the general formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ each have a diazonioaryl group as a substituent, and a plurality of diazonium groups You may have.

Specific examples of the diazonium salt compound represented by the general formula (2) are described in, for example, paragraphs [0062] to [0064] of JP-A No. 2004-075649 (Exemplary Compounds A-1 to A -30).
The method for synthesizing the diazonium salt compound represented by the general formula (2) is described in paragraph numbers [0065] to [0080] of the same publication.

  -Compound represented by general formula (3)-

In the general formula (3), R ¹ and R ² each independently represents an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group or a carbamoyl group, and R ¹ and R ² are bonded to each other to form a ring. May be. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, halogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group or -N ₂ ⁺ X ^- represents a. However, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion.

The alkyl group represented by R ¹ and R ² may be unsubstituted or substituted. Examples of the substituent that can be introduced into the alkyl group include a phenyl group, a halogen atom, and an alkoxy group. An aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the alkyl group represented by R ¹ and R ² is preferably an alkyl group having 1 to 30 carbon atoms in total, for example, a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, Isobutyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2-hydroxyethyl group, 2-benzoyloxyethyl group, 2- (4-Butoxyphenoxy) ethyl group, benzyl group, allyl group, methoxyethyl group, ethoxyethyl, dibutylaminocarbonylmethyl group are preferred.
Among these, a C1-C18 alkyl group is preferable, and a methyl group, an ethyl group, a normal propyl group, a normal butyl group, an isobutyl group, a decyl group, an octyl group, a benzyl group, and a methoxyethyl group are particularly preferable.

The aryl group represented by R ¹ and R ² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the aryl group include a phenyl group, a halogen atom, and an alkoxy group. An aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the aryl group represented by R ¹ and R ² is preferably an aryl group having 6 to 30 carbon atoms in total, such as a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and 4-butoxy. A phenyl group is preferred.

The acyl group represented by R ¹ and R ² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the acyl group include a phenyl group, a halogen atom, and an alkoxy group. An aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the acyl group represented by R ¹ and R ² is preferably an acyl group having 1 to 20 carbon atoms in total, for example, an acetyl group, a propanoyl group, a butanoyl group, a hexanoyl group, an octanoyl group, a decanoyl group. A benzoyl group is preferable.
Among these, an acyl group having 1 to 10 carbon atoms is preferable, and an acetyl group, a propanoyl group, and a butanoyl group are particularly preferable.

The alkoxycarbonyl group represented by R ¹ and R ² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the alkoxycarbonyl group include a phenyl group, a halogen atom, Alkoxy groups, aryloxy groups, alkoxycarbonyl groups, acyloxy groups, acylamino groups, carbamoyl groups, cyano groups, carboxylic acid groups, sulfonic acid groups, and heterocyclic groups are preferred.
Specifically, the alkoxycarbonyl group represented by R ¹ and R ² is preferably an alkoxycarbonyl group having 2 to 30 carbon atoms in total, such as a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, an octyloxycarbonyl group, or dodecyl. Preferred examples include an oxycarbonyl group, a 2-phenoxyethoxycarbonyl group, and a benzyloxycarbonyl group.
Among these, a C2-C15 alkoxycarbonyl group is preferable and a methoxycarbonyl group, an ethoxycarbonyl group, and a butoxycarbonyl group are especially preferable.

The carbamoyl group represented by R ¹ and R ² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the carbamoyl group include a phenyl group, a halogen atom, and an alkoxy group. An aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the carbamoyl group represented by R ¹ and R ² is preferably a carbamoyl group having 1 to 30 carbon atoms in total, such as N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N, N -Dipropylcarbamoyl group, N, N-dibutylcarbamoyl group, N, N-dioctylcarbamoyl group, N, N-bis (2-ethylhexyl) carbamoyl group, N-ethyl-N-benzylcarbamoyl group, N-ethyl-N Preferred examples include -butylcarbamoyl group, N-ethyl-N-phenylcarbamoyl group, piperidinocarbonyl group, pyrrolidinocarbonyl group, morpholinocarbonyl group, and 4-octanoylpiperazinocarbonyl group.

When R ¹ and R ² are bonded to each other to form a ring, the total number of carbon atoms including R ¹ and R ² is preferably 2 to 20, and the formed ring further has a substituent. May be. The number of rings formed is preferably a 5- to 8-membered ring including the nitrogen atom. Specifically, the ring structure including the nitrogen atom to which R ¹ and R ² are bonded includes pyrrolidine ring, piperidine ring, morpholine ring, thiomorpholine ring, hexamethyleneimine ring, heptamethyleneimine ring, phthalimide ring. , A pyrrolidone ring, and a piperidone ring are preferable, and these may further have a substituent.

The halogen atom represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably a chlorine atom, a bromine atom or an iodine atom.

The alkyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or have a substituent. Examples of the substituent that can be introduced into the alkyl group include a phenyl group, A halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferred.
Specifically, the alkyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkyl group having 1 to 30 carbon atoms, for example, a methyl group, an ethyl group, a normal propyl group, isopropyl Group, normal butyl group, isobutyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2-hydroxyethyl group, 2-benzoyl group Preferable examples include oxyethyl group, 2- (4-butoxyphenoxy) ethyl group, benzyl group, allyl group, methoxyethyl group, ethoxyethyl group, and dibutylaminocarbonylmethyl group.
Among these, a C1-C20 alkyl group is preferable and a methyl group, an ethyl group, a normal propyl group, a normal butyl group, a decyl group, a benzyl group, and a methoxyethyl group are especially preferable.

The aryl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced into the aryl group include a phenyl group, A halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferred.
Specifically, the aryl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an aryl group having 6 to 30 carbon atoms in total, such as a phenyl group, a 4-chlorophenyl group, and a 4-methylphenyl group. 4-butoxyphenyl group is preferable.

The alkoxy group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or have a substituent. Examples of the substituent that can be introduced into the alkoxy group include a phenyl group, A halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferred.
Specifically, the alkoxy group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkoxy group having 1 to 30 carbon atoms in total, for example, methoxy group, ethoxy group, propyloxy group, butoxy Group, 3-pentyloxy group, 2-ethylhexyloxy group, hexyloxy group, octyloxy group, 3,5,5-trimethylhexyloxy group, dodecyloxy group, octadecyloxy group, 2-ethoxyethoxy group, 2-chloro Preferred examples include ethoxy group, 2-phenoxyethoxy group, benzyloxy group, ethoxycarbonylmethoxy group, butoxycarbonylmethoxy group, dibutylaminocarbonylmethoxy group, and diethylaminocarbonylmethoxy group.

The aryloxy group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced into the aryloxy group include phenyl Group, halogen atom, alkoxy group, aryloxy group, alkoxycarbonyl group, acyloxy group, acylamino group, carbamoyl group, cyano group, carboxylic acid group, sulfonic acid group, and heterocyclic group are preferred.
Specifically, the aryloxy group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an aryloxy group having 6 to 30 carbon atoms in total, such as a phenoxy group, a 4-chlorophenoxy group, 2- Preferable examples include methylphenoxy group, 4-methoxyphenoxy group, 4-cyanophenoxy group, 4-ethoxycarbonylphenoxy group, 4-dibutylaminocarbonylphenoxy group, and 3,5-dichlorophenoxy group.

The alkylthio group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or have a substituent. Examples of the substituent that can be introduced into the alkylthio group include a phenyl group, A halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferred.
Specifically, the alkylthio group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkylthio group having 1 to 20 carbon atoms in total, for example, methylthio group, ethylthio group, butylthio group, cyclohexylthio group. Preferred examples include a group, an octylthio group, a 2-ethylhexylthio group, a dodecylthio group, a 2-hydroxyethylthio group, and a benzylthio group.
Among these, a C1-C15 alkylthio group is preferable and a methylthio group, an ethylthio group, a butylthio group, and an octylthio group are especially preferable.

The arylthio group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced into the arylthio group include a phenyl group, A halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferred.
Specifically, the arylthio group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an arylthio group having 6 to 20 carbon atoms in total, such as a phenylthio group, a 2-butoxycarbonylphenylthio group, Preferred examples include 2-chlorophenylthio group, 4-chlorophenylthio group, and 4-methylphenylthio group.

The alkylsulfonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced into the alkylsulfonyl group include phenyl Group, halogen atom, alkoxy group, aryloxy group, alkoxycarbonyl group, acyloxy group, acylamino group, carbamoyl group, cyano group, carboxylic acid group, sulfonic acid group, and heterocyclic group are preferred.
Specifically, the alkylsulfonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkylsulfonyl group having 1 to 20 carbon atoms in total, for example, methylsulfonyl group, butylsulfonyl group, octyl Preferred examples include a sulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, and benzylsulfonyl group.

The arylsulfonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced into the arylsulfonyl group include phenyl Group, halogen atom, alkoxy group, aryloxy group, alkoxycarbonyl group, acyloxy group, acylamino group, carbamoyl group, cyano group, carboxylic acid group, sulfonic acid group, and heterocyclic group are preferred.
Specifically, the arylsulfonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an arylsulfonyl group having 6 to 30 carbon atoms in total, such as a phenylsulfonyl group, 2-chlorophenylmethylsulfonyl. Preferred examples include a group, a 2-chlorophenylsulfonyl group, a 4-chlorophenylsulfonyl group, and a 4-chlorophenylmethylsulfonyl group.

In —N ₂ ⁺ X ⁻ represented by R ³ , R ⁴ , R ⁵ and R ⁶ , X ⁻ represents an anion. At least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ .
The anion represented by X ⁻ may be either an inorganic anion or an organic anion, and any anion can be selected. As the inorganic anion, for example, hexafluorophosphate ion, borohydrofluoric acid ion, chloride ion, and sulfate ion are preferable, and hexafluorophosphate ion and borohydrofluoric acid ion are particularly preferable. As the organic anion, for example, polyfluoroalkylcarboxylate ions, polyfluoroalkylsulfonate ions, tetraphenylborate ions, aromatic carboxylate ions, and aromatic sulfonate ions are preferable.

  Among the diazonium salt compounds represented by the general formula (3), a diazonium salt compound represented by the following general formula (3-1) is more preferable, and a diazonium salt compound represented by the following general formula (3-2) Is more preferable.

In General Formula (3-1), R ¹ and R ² each independently represents an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a carbamoyl group, and R ¹ and R ² are bonded to each other to form a ring. It may be formed. R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group or an arylsulfonyl group. X ⁻ represents an anion.

In the general formula (3-1), R ¹ and R ² in formula (3) have the same meanings as R ¹ and R ^2, are the preferable examples. R ⁷ , R ⁸ and R ⁹ are synonymous with R ³ , R ⁴ and R ^{6 in the} general formula (3), and preferred examples are also the same. X ^- is the general formula (3) in R ^3, R ^4, -N represented by R ⁵ and R ⁶ ₂ ⁺ X ^- in X ^- in the above formula, and preferred examples are also the same.

In general formula (3-2), R ¹ and R ² each independently represents an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a carbamoyl group, and R ¹ and R ² are bonded to each other to form a ring. It may be formed. R ¹⁰ and R ¹¹ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group or an arylsulfonyl group. R ¹² represents a hydrogen atom, an alkyl group or an aryl group. X ⁻ represents an anion.

In the general formula (3-2), R ¹ and R ² in formula (3) have the same meanings as R ¹ and R ^2, are the preferable examples. R ¹⁰ and R ¹¹ have the same meanings as R ³ and R ^{6 in} formula (3), and preferred examples are also the same. X ^- is the general formula (3) in R ^3, R ^4, -N represented by R ⁵ and R ⁶ ₂ ⁺ X ^- in X ^- in the above formula, and preferred examples are also the same.

The alkyl group represented by R ¹² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the alkyl group include a phenyl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the alkyl group represented by R ¹² is preferably an alkyl group having 1 to 30 carbon atoms in total, methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, isobutyl group, normal pentyl. Group, isopentyl group, 3-pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2-ethylhexyl group, 3,5,5-trimethylhexyl group, decyl group, dodecyl group, octadecyl group, 2 -Hydroxyethyl group, 2-benzoyloxyethyl group, 2- (4-butoxyphenoxy) ethyl group, benzyl group, allyl group, methoxyethyl group, ethoxyethyl group, dibutylaminocarbonylmethyl group, diethylaminocarbonylmethyl group are preferred Can be mentioned.

The aryl group represented by R ¹² may be unsubstituted or substituted, and examples of the substituent that can be introduced into the aryl group include a phenyl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, and a heterocyclic group are preferable.
Specifically, the aryl group represented by R ¹² is preferably an aryl group having 6 to 30 carbon atoms, and preferably a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and a 4-butoxyphenyl group. Can be mentioned.

Specific examples of the diazonium salt compounds represented by the above general formulas (3), (3-1) and (3-2) include, for example, paragraph numbers [0063] to [0069] of JP-A-2004-099482. (Exemplary compounds A-1 to A-77) described in the above.
The method for synthesizing the diazonium salt compounds represented by the general formulas (3), (3-1) and (3-2) is described in paragraph [0070] of the same publication.

  The diazonium salt compounds represented by the general formulas (2) and (3) may be used alone or in combination of two or more. Further, the diazonium salt compound represented by the general formulas (2) and (3) and a known diazonium salt compound can be used in combination according to various purposes such as hue adjustment. When the diazonium salt compound represented by the general formulas (2) and (3) and the known diazonium salt compound are used in combination, the diazonium salt compound represented by the general formulas (2) and (3) is contained in the recording layer. It is preferably 50% by mass or more, more preferably 80% by mass or more, based on the total diazonium salt compound.

  Examples of the known diazonium salt compounds include 4-diazo-1-dimethylaminobenzene, 4-diazo-2-butoxy-5-chloro-1-dimethylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4- Diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-dibutoxybenzene, 4- Diazo-1-toluylmercapto-2,5-diethoxybenzene, 4-diazo-1-piperazino-2-methoxy-5-chlorobenzene, 4-diazo-1- (N, N-dioctylaminocarbonyl) benzene, 4 -Diazo-1- (4-t-octylphenoxy) benzene, 4-diazo-1- (2-ethyl) Xanoylpiperidino) -2,5-dibutoxybenzene, 4-diazo-1- [α- (2,4-di-t-amylphenoxy) butyrylpiperidino] benzene, 4-diazo-1- ( 4-methoxy) phenylthio-2,5-diethoxybenzene, 4-diazo-1- (4-methoxy) benzamide-2,5-diethoxybenzene, 4-diazo-1-pyrrolidino-2-methoxybenzene and the like are preferable. .

  In addition, in the heat-sensitive recording material of the present invention, it is necessary to encapsulate a diazonium salt compound in a microcapsule, as described in detail later, in order to improve the raw storage stability before use of the recording material. However, in this case, since the diazonium salt compound is used after being dissolved in an appropriate solvent, the diazonium salt compound preferably has an appropriate solubility in these solvents and low water solubility. Specifically, it has a solubility of 5% or more with respect to the organic solvent to be used, and the solubility in water is preferably 1% or less.

In the heat-sensitive recording material of the present invention, the diazonium salt compound is preferably contained in the recording layer in the range of 0.02 to 3 g / m ² , and particularly 0.1 to ² g / m ² from the viewpoint of color density. It is preferable to make it contain in the range.

(Micro capsule)
In the heat-sensitive recording material of the present invention, a diazonium salt compound is encapsulated in microcapsules in order to improve the raw storage stability before use.
The microcapsules used in this case are prepared by dissolving a solution in which a diazonium salt compound and the same or different compound that reacts with each other to form a polymer substance are dissolved in a hydrophobic organic solvent in a hydrophilic protective colloid solution. After emulsification and dispersion, the temperature of the solution is raised while reducing the pressure of the reaction vessel to move the wall-forming substance to the surface of the oil droplet while distilling off the solvent, and the polymer formation reaction is performed by polyaddition or polycondensation on the surface of the oil droplet. Produced by advancing to form a wall film.

  The polymer substance forming the microcapsule wall is preferably at least one selected from polyurethane and polyurea.

A method for producing the diazonium salt compound-containing microcapsules (polyurea / polyurethane wall) in the recording material of the present invention will be described below.
First, the diazo compound is dissolved in a hydrophobic organic solvent that becomes the core of the capsule. As the hydrophobic organic solvent used in this case, an organic solvent having a boiling point of 100 ° C. to 300 ° C. is preferable, and aromatic hydrocarbons, halogenated hydrocarbons, carboxylic acid esters, phosphate esters, sulfate esters, Examples include sulfonic acid esters, ketones, and ethers. Specific examples of the organic solvent include alkyl naphthalene, alkyl diphenyl ethane, alkyl diphenyl methane, alkyl biphenyl, chlorinated paraffin, trixyl phosphate, tricresyl phosphate, maleic acid dioctyl ester, adipic acid dibutyl ester and the like. These may be used individually by 1 type and may use 2 or more types together.

  Moreover, when the solubility of the diazonium salt compound to be encapsulated in the organic solvent is poor, a low-boiling solvent having high solubility in the diazonium salt compound can be used in combination. Specific examples of the low boiling point solvent include ethyl acetate, butyl acetate, methylene chloride, tetrahydrofuran, and acetone. Further, a polyvalent isocyanate is further added as a wall material (oil phase) in the hydrophobic organic solvent that becomes the core of the microcapsule.

  On the other hand, as the aqueous phase, an aqueous solution in which a water-soluble polymer such as polyvinyl alcohol or gelatin is dissolved is prepared, and then the oil phase is added and emulsified and dispersed by means such as a homogenizer. At this time, the water-soluble polymer acts as a stabilizer for emulsion dispersion. In order to carry out emulsification and dispersion more stably, a surfactant may be added to at least one of the oil phase and the aqueous phase.

  The amount of polyisocyanate used is determined so that the average particle size of the microcapsules is 0.3 to 12 μm and the wall thickness is 0.01 to 0.3 μm. The dispersed particle size is generally about 0.2 to 10 μm. In the emulsified dispersion, a polyisocyanate polymerization reaction occurs at the interface between the oil phase and the aqueous phase to form polyurea walls.

  If a polyol is added to the aqueous phase, the polyvalent isocyanate and the polyol can react to form a polyurethane wall. In order to increase the reaction rate, it is preferable to keep the reaction temperature high or to add an appropriate polymerization catalyst. The polyisocyanate, polyol, reaction catalyst, polyamine for forming a part of the wall agent, etc. are well known in the book (edited by Keiji Iwata, Polyurethane Handbook Nikkan Kogyo Shimbun (1987)).

  As the polyvalent isocyanate compound used as a raw material for the microcapsule wall, a compound having a trifunctional or higher functional isocyanate group is preferable, but a bifunctional isocyanate compound may be used in combination, or a bifunctional isocyanate compound may be used alone. . Specifically, xylene diisocyanate and hydrogenated products thereof, hexamethylene diisocyanate, tolylene diisocyanate and hydrogenated products thereof, and diisocyanates such as isophorone diisocyanate are used as main raw materials, and these dimers or trimers (burette or isosinurate). In addition, polyfunctional adducts with polyols such as trimethylolpropane, formalin condensates of benzene isocyanate, and the like.

  Furthermore, a polyol or polyamine can be added to a hydrophobic solvent serving as a core or a water-soluble polymer solution serving as a dispersion medium, and used as one of raw materials for a microcapsule wall. Specific examples of these polyols or polyamines include propylene glycol, glycerin, trimethylolpropane, triethanolamine, sorbitol, hexamethylenediamine and the like. When a polyol is added, a polyurethane wall is formed.

  The water-soluble polymer used in the water-soluble polymer aqueous solution for dispersing the oil phase of the capsule thus prepared is preferably a water-soluble polymer having a water solubility of 5 or more at the temperature to be emulsified. As polyvinyl alcohol and its modified products, polyacrylic acid amide and its derivatives, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer. Examples include polymers, polyvinylpyrrolidone, ethylene-acrylic acid copolymers, vinyl acetate-acrylic acid copolymers, carboxymethylcellulose, methylcellulose, casein, gelatin, starch derivatives, arabic gum, and sodium alginate.

  These water-soluble polymers preferably have no or low reactivity with isocyanate compounds. For example, those having a reactive amino group in the molecular chain, such as gelatin, can be modified by modification beforehand. It is necessary to eliminate this. Moreover, when adding surfactant, it is preferable that the addition amount of surfactant is 0.1%-5% with respect to the mass of an oil phase, especially 0.5%-2%.

  For emulsification, a known emulsification apparatus such as a homogenizer, a manton gorey, an ultrasonic disperser, or a teddy mill can be used. After emulsification, the emulsion is heated to 30 to 70 ° C. in order to promote the capsule wall formation reaction. Further, during the reaction, in order to prevent aggregation between the capsules, it is necessary to add water to reduce the collision probability between the capsules or to perform sufficient stirring.

  Further, a dispersing agent for preventing aggregation may be added again during the reaction. As the polymerization reaction proceeds, the generation of carbon dioxide gas is observed, and its end can be regarded as the approximate end point of the capsule wall formation reaction. Usually, the target diazonium salt compound-containing microcapsules can be obtained by reacting for several hours.

(Non-dissociative coupler)
In the heat-sensitive recording materials (first heat-sensitive recording material and second heat-sensitive recording material) of the present invention, it is necessary to use a non-dissociative coupler as a coupler, and more effectively improve the color developability. From the viewpoint, it is preferable to use a hydrophobic one.
Here, the non-dissociation-type coupler refers to a coupler whose acid dissociation constant (pKa) cannot be determined for any of the following reasons even when any of the following methods is used.
(1) Using a solution obtained by dissolving a coupler in a THF / water = 6/4 (mass) mixed solution, 0.1N sodium hydroxide using an acid dissociation constant measuring apparatus (Com-980Wn, manufactured by Hiranuma Sangyo Co., Ltd.) No inflection point is observed even when titrated with an aqueous solution.
(2) The UV spectrum of a solution in which the coupler is dissolved in a THF / pH buffer aqueous solution = 5/5 (mass) mixed solution is measured, and even if the pH 12 buffer aqueous solution is used, it is compared with the UV spectrum in the low pH buffer aqueous solution. Inflection points are not observed.

  As the non-dissociative coupler used in the present invention, an amino-substituted hetero 5-membered ring and an alkylaniline are preferable. Specific examples include aminopyrazoles, 3-aminopyrroles, 3-aminofurans, and 3-aminothiophenes. And couplers such as 5-aminoisoxazoles, 4-aminoisothiazoles, 4-aminoimidazoles, N, N-dialkylanilines, and N, N-dialkylnaphthalenes. Of these, aminopyrazoles, 3-aminopyrroles, 3-aminofurans, 3-aminothiophenes, 5-aminoisoxazoles, 4-aminoisothiazoles, 4-aminoimidazoles are more preferable. And more preferably aminopyrazoles, 3-aminopyrroles, 5-aminoisoxazoles, and 4-aminoimidazoles. Among these, couplers of aminopyrazoles (aminopyrazole type) are particularly preferable.

  Specific examples of the aminopyrazole couplers include those represented by the following general formula (4).

In the general formula (4), R ³¹ represents a hydrogen atom, an alkyl group, an aryl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, a carbamoyl group, a carbonamido group, a sulfonamido group, or an alkoxycarbonyl group, and R ³² represents A hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkoxycarbonyl group, a carbamoyl group, a carbonamido group, or a sulfonamido group is represented.

In the general formula (4), the alkyl group represented by R ³¹ or R ^32, preferably an alkyl group having 1 to 20 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, and an n-octyl group. 2-ethylhexyl group, t-octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, n-hexadecyl group, 2-hexyldecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl Groups and the like.

  The alkyl group may further have a substituent. Examples of the substituent include a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, and a cyano group. , Carboxylic acid group, sulfonic acid group, heterocyclic group and the like.

  Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl. Group, octyl group, t-octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2-hydroxyethyl group, 2-benzoyloxyethyl group, 2- (4-butoxyphenoxy) ethyl group, benzyl group Allyl group, methoxyethyl group, ethoxyethyl, and dibutylaminocarbonylmethyl group are preferred.

The aryl group represented by R ³¹ or R ³² is preferably an aryl group having 6 to 25 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The aryl group may further have a substituent. Examples of the substituent include a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, and a cyano group. Group, carboxylic acid group, sulfonic acid group, heterocyclic group and the like.
As the aryl group, in particular, phenyl group, 4-chlorophenyl group, 4-methylphenyl group, 4-butoxyphenyl group, 2-methoxyphenyl group, 2-hydroxyphenyl group, 2-hydroxy-5-octylphenyl group, 2,5-diheptyloxyphenyl group and 2-hydroxy-5-butoxyphenyl group are preferred.

The alkylsulfonyl group represented by R ³¹ is preferably an alkylsulfonyl group having 1 to 20 carbon atoms, for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfonyl group, octylsulfonyl group, decylsulfonyl group, dodecylsulfonyl group. Groups and the like.
The alkylsulfonyl group may further have a substituent. Examples of the substituent include a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, and a cyano group. , Carboxylic acid group, sulfonic acid group, heterocyclic group and the like.
As the alkylsulfonyl group, a methylsulfonyl group, a butylsulfonyl group, an octylsulfonyl group, a decylsulfonyl group, a dodecylsulfonyl group, and a benzylsulfonyl group are particularly preferable.

The arylsulfonyl group represented by R ³¹ is preferably one having 6 to 20 carbon atoms, and examples thereof include a benzenesulfonyl group.
The arylsulfonyl group may further have a substituent. Examples of the substituent include an alkyl group, a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, and a carbamoyl group. , Cyano group, carboxylic acid group, sulfonic acid group, heterocyclic group and the like.
As the arylsulfonyl group, a benzenesulfonyl group, a toluenesulfonyl group, a chlorobenzenesulfonyl group, a butoxybenzenesulfonyl group, and a 2,5-dibutoxybenzenesulfonyl group are particularly preferable.

The acyl group represented by R ³¹ is preferably one having 2 to 20 carbon atoms, and the portion other than the carbonyl group of the acyl group may be any of aliphatic, aromatic and heterocyclic groups.
The acyl group may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, and a halogen atom.
Examples of the acyl group include acetyl, propanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, octadecanoyl, benzoyl, phenoxyacetyl, 2-ethylhexanoyl, 2,5-di A butoxybenzoyl group is preferred.

The carbamoyl group represented by R ³¹ or R ³² may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, and a halogen atom.
As the substituted carbamoyl group, an ethylaminocarbonyl group, a butylaminocarbonyl group, a hexylaminocarbonyl group, a diethylaminocarbonyl group, an ethoxyethylaminocarbonyl group, a phenylaminocarbonyl group, a tolylaminocarbonyl group, and a benzylaminocarbonyl group are particularly preferable.

The carbonamido group represented by R ³¹ or R ³² may be either an aliphatic or aromatic carbonamido group, and preferably has 2 to 20 carbon atoms.
The carbonamido group may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, and a halogen atom.
As the carbonamide group, in particular, an acetamide group, butanamide group, hexanamide group, decanamide group, tetradecanamide group, 2-ethylhexanamide group, benzylamide group, benzoylamide group, 2,5-dibutoxyphenylcarbonamide group Is preferred.

The sulfonamide group represented by R ³¹ or R ³² may be either an aliphatic or aromatic sulfonamide group, and the number of carbon atoms is preferably 1-20.
The sulfonamide group may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, and a halogen atom.
Examples of the sulfonamide group include methanesulfonamide group, butanesulfonamide group, octanesulfonamide group, decanesulfonamide group, 2-ethylhexylsulfonamide group, phenylsulfonamide group, 2-butoxyphenylsulfonamide group, 4 -A chlorophenylsulfonamide group, a 2,5-diethoxysulfonamide group, and a 4-hexyloxyphenylsulfonamide group are preferable.

The amino group represented by R ³² may be unsubstituted, substituted, or substituted, and the substituent may be either aliphatic or aromatic.
The amino group may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, and a halogen atom.
As the amino group, an unsubstituted amino group, a butylamino group, a hexylamino group, a butoxyethylamino group, a dibenzylamino group, a phenylamino group, and a phenylmethylamino group are particularly preferable.

The alkoxycarbonyl group represented by R ³¹ or R ³² is preferably an alkoxycarbonyl group having 2 to 20 carbon atoms.
The alkoxycarbonyl group may further have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, a halogen atom, and a hydroxyl group.
Examples of the alkoxycarbonyl group include a methyloxycarbonyl group, an ethyloxycarbonyl group, a butyloxycarbonyl group, a 2-ethylhexyloxycarbonyl group, a decyloxycarbonyl group, an ethoxyethoxycarbonyl group, a phenyloxycarbonyl group, and 2-chlorophenyloxy. A carbonyl group and a 4-ethoxyphenyloxycarbonyl group are preferred.

The alkoxy group represented by R ³² is preferably an alkoxy group having 1 to 20 carbon atoms, and may have a substituent.
Examples of the alkoxy group include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, t-butyloxy group, n-hexyloxy group, n-octyloxy group, and 2-ethylhexyloxy. Group, 3,5,5-trimethylhexyloxy group, n-decyloxy group, n-dodecyloxy group, cyclohexyloxy group, benzyloxy group, allyloxy group, 2-methoxyethoxy group, 2-ethoxyethoxy group, 2-phenoxy Ethoxy group, 2- (2,5-di-t-amylphenoxy) ethoxy group, 2-benzoyloxyethoxy group, methoxycarbonylmethyloxy group, methoxycarbonylethyloxy group, butoxycarbonylethyloxy group, 2-isopropyloxyethyl An oxy group is preferred. Of these, an alkoxy group having 1 to 10 carbon atoms is preferable, and a methoxy group, an ethoxy group, a t-butyloxy group, and an n-hexyloxy group are particularly preferable.

The aryloxy group represented by R ³² is preferably an aryloxy group having 6 to 30 carbon atoms, and may have a substituent.
As the aryloxy group, for example, a phenyloxy group, a 4-methylphenyloxy group, a 3-methylphenyloxy group, a 2-methylphenyloxy group, a 4-chlorophenyloxy group, and a 2-chlorophenyloxy group are preferable. Among them, an aryloxy group having 6 to 15 carbon atoms is more preferable.

  Of the non-dissociative couplers represented by the general formula (4), those represented by the following general formula (5) are more preferable.

In the general formula (5), R ³³ represents an alkyl group or an aryl group, and Ar ′ represents an aryl group.

In the general formula (5), the alkyl group represented by R ^33, and examples of the aryl group represented by R ³³ and Ar ', the same as those listed above general formula (4) as R ³¹ and R ³² Things.

  Hereinafter, preferred specific examples of the aminopyrazole couplers represented by the general formula (4) and the general formula (5) that can be used in the present invention will be given, but the present invention is not limited thereto.

  The compounds represented by the general formula (4) and the general formula (5) are known compounds and can be synthesized by the synthesis methods described in various report examples. For example, Zh.Obshch.kim.1961,2311, Chem.Ber.1909,67, Japanese Patent Laid-Open No. 63-313774, Japanese Patent Laid-Open No. 61-236768, and Japanese Patent Laid-Open No. 4-275277 are used. Can be synthesized.

Here, a preferred combination of a diazonium salt compound and a non-dissociative coupler in the present invention will be described.
Among the diazonium salt compounds and non-dissociative couplers described above, in the diazonium salt compound represented by the general formula (2) or the general formula (3), a substituent represented by R ^{21 to} R ²⁶ or R ^{1 to} R ⁶ A diazonium salt compound having a total carbon number of 13 or more, and 3-aminopyrroles, 3-aminofurans, 3-aminothiophenes, 5-aminoisoxazoles, 4-aminoisothiazoles, 4- A combination with a non-dissociative coupler of any of aminoimidazoles and 5-aminopyrazoles is preferred. In the diazonium salt compound represented by the general formula (2) or the general formula (3), the total number of carbon atoms contained in the substituent represented by R ^{21 to} R ²⁶ or R ^{1 to} R ⁶ is 14 or more. A combination of a diazonium salt compound and a non-dissociative coupler of any of 3-aminopyrroles, 4-aminoimidazoles, and 5-aminopyrazoles is more preferable.

  In the present invention, a known coupler that forms a dye by coupling with a diazonium salt compound in a basic atmosphere may be used together with the non-dissociative coupler as necessary for the purpose of hue adjustment or the like. it can. When the coupler and a known coupler are used in combination, 50% by mass or more of all couplers contained in the recording layer is preferably the non-dissociative coupler, and more preferably 70% by mass or more.

  Examples of the known coupler include so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives, and the like.

  More specifically, the known couplers include resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2, 3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfonaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid anilide, benzoyl Acetanilide, 1-phenyl-3-methyl-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-anilino-5-pyrazolone, 2- {3- [α- (2,4-di- t-amylphenoxy) butanamide] benzamide} phenol, 2 4- bis - (benzoylacetonate amino) toluene, 1,3-bis - (pivaloyl acetamide aminomethyl) include benzene and the like.

  The total content of couplers in the recording layer is preferably 0.2 to 8 mol, more preferably 0.5 to 4 mol, relative to 1 mol of the diazonium salt compound. When the total content of the coupler is 0.2 mol or more with respect to 1 mol of the diazonium salt compound, sufficient color developability can be obtained, and when it is 8 mol or less, coating suitability can be suitably maintained.

(Coloring aid)
In the present invention, a coloring aid can be added for the purpose of promoting the coloring reaction. The color assistant is a substance that increases the color density during heat recording or lowers the minimum color development temperature, and lowers the melting point of couplers, diazonium salt compounds, etc., and lowers the softening point of the capsule wall. Thus, a situation in which a diazonium salt compound, a coupler, etc. are likely to react is created.

  As a color developing aid used in the heat-sensitive recording material of the present invention, for example, a phenol derivative, a naphthol derivative, an alkoxy-substituted benzene, an alkoxy-substituted naphthalene, Hydroxy compounds, amide compounds, sulfonamide compounds and the like can be added. These compounds are considered to lower the melting point of the coupler or improve the heat permeability of the microcapsule wall, and as a result, enable a high color density.

  The color forming aid used in the heat-sensitive recording material of the present invention may be a heat-meltable substance. The heat-meltable substance is a substance having a melting point of 50 ° C. to 150 ° C. that is solid at room temperature and melts by heating, and is a substance that dissolves a diazonium salt compound, a coupler, and the like. Specific examples of these compounds include carboxylic acid amides, N-substituted carboxylic acid amides, ketone compounds, urea compounds, esters and the like.

(Other additives)
In the heat-sensitive recording material of the present invention, the following known antioxidants are used for the purpose of improving fastness to light and heat of a thermochromic image or reducing yellowing due to light of an unprinted portion after fixing. Etc. are preferably used.

  As for the above-mentioned antioxidant, for example, European Published Patent No. 223739, No. 309401, No. 309402, No. 310551, No. 310552, No. 457416, German Published Patent No. 3435443, JP-A-54-48535, JP-A-62-262047, JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262, JP-A-3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. Nos. 4,814,262 and 4,980,275.

  Furthermore, it is also effective to use various known additives already used in heat-sensitive recording materials and pressure-sensitive recording materials. Specific examples of these antioxidants include JP-A-60-107384, JP-A-60-107383, JP-A-60-125470, JP-A-60-125471, JP-A-60-125472, and JP-A-60. -287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-185483, 61-2111079, 62- 146678, 62-146680, 62-146679, 62-28285, 63-051174, 63-89877, 63-88380, 63-088381 Gazette, 63-203372 gazette, 63-224989 gazette, 63-251 gazette. No. 82, No. 63-267594, No. 63-182484, JP-A-01-239282, No. 04-291658, No. 04-291684, No. 05-188687, No. 05- 188686, 05-110490, 05-1108437, 05-170361, Japanese Patent Publication No. 48-033294, 48-033212, and the like. it can.

  Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3 4-tetrahydroquinoline, nickel cyclohexaneate, 2,2-bis-4-hydroxyphenylpropane, 1,1-bis-4-hydroxyphenyl-2-ethylhexane, 2-methyl-4-methoxydiphenylamine, 1-methyl- Examples include 2-phenylindole.

  The addition amount of these antioxidants is preferably 0.05 to 100 parts by mass, and particularly preferably 0.2 to 30 parts by mass with respect to 1 part by mass of the diazonium salt compound. The above-mentioned known antioxidants can be used in a microcapsule together with a diazonium salt compound, or can be used as a solid dispersion or as an emulsion together with a suitable emulsifying aid, together with a coupler or other coloring aid. Can be used in both forms. Of course, one or more antioxidants can be used in combination. Further, a protective layer may be provided on the recording layer, and the protective layer may be added or exist.

  These antioxidants need not be added to the same layer. When these antioxidants are used in combination, they are structurally classified as anilines, alkoxybenzenes, hindered phenols, hindered amines, hydroquinone derivatives, phosphorus compounds, sulfur compounds, and different structures. These may be combined, or a plurality of the same may be combined.

  The coupler used in the present invention can be used as a solid dispersion with a water-soluble polymer using a sand mill or the like together with other coloring aids and the like, but it is particularly preferable to use it as an emulsion together with a suitable emulsifying aid. Preferred water-soluble polymers include water-soluble polymers used when preparing microcapsules (see, for example, JP-A-59-190886). In this case, the coupler and the coloring aid are added in an amount of 5 to 40% by mass with respect to the water-soluble polymer solution. The dispersed or emulsified particle size is preferably 10 μm or less.

  To the heat-sensitive recording material of the present invention, a free radical generator (compound that generates free radicals by light irradiation) used in a photopolymerizable composition or the like is added for the purpose of reducing yellowing of the background after fixing. Can do. Examples of such free radical generators include aromatic ketones, quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, acyl oxime esters, and the like. The amount to be added is preferably 0.01 to 5 parts by mass of the free radical generator with respect to 1 part by mass of the diazonium salt compound.

  Similarly, for the purpose of reducing yellowing, a polymerizable compound having an ethylenically unsaturated bond (hereinafter sometimes referred to as “vinyl monomer”) can also be used. The vinyl monomer is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and has a chemical form of monomer or prepolymer. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, amide compounds of unsaturated carboxylic acids and aliphatic polyvalent amines, and the like.

  The vinyl monomer is preferably used at a ratio of 0.2 to 20 parts by mass with respect to 1 part by mass of the diazonium salt compound. The above free radical generator and vinyl monomer can be used in a microcapsule together with a diazonium salt compound. In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like can be added as an acid stabilizer.

The heat-sensitive recording material of the present invention is prepared by preparing a coating solution containing a microcapsule containing a diazonium salt compound, a coupler, and other additives, and coating a bar or blade on a support such as paper or a synthetic resin film. It is preferable to provide a heat-sensitive recording layer having a solid content of 2.5 to 30 g / m ² by coating and drying by a coating method such as air knife coating, gravure coating, roll coating coating, spray coating, dip coating or curtain coating.

  In the heat-sensitive recording material of the present invention, microcapsules, couplers and the like may be contained in the same layer, but it is also possible to adopt a laminated type constitution in which they are contained in another layer. Further, after providing an intermediate layer as described in JP-A No. 61-054980 on the support, a heat-sensitive recording layer can be applied.

<Support>
As the support used in the heat-sensitive recording material of the present invention, any paper support used for ordinary pressure-sensitive paper, heat-sensitive paper, dry or wet diazo copy paper, etc. can be used, as well as alkyl ketene dimers. Sizing with a neutral sizing agent, etc., and neutral paper having a pH of 5 to 9 (as described in JP-A No. 56-112383), as described in JP-A No. 57-116687. A paper having a Beck smoothness of 90 seconds or more, an optical surface roughness of 8 μm or less and a thickness of 30 to 150 μm described in JP-A-58-136492 Paper, a paper having a density of 0.9 g / cm ³ or less described in JP-A-58-69091 and an optical contact ratio of 15% or more, a Canadian standard described in JP-A-58-69097 Drainage Gloss of paper made by Yankee machine described in Japanese Patent Application Laid-Open No. 58-65695, paper that prevents the coating liquid from being made from pulp pulped to 400 ml (400 cc) or more by (JIS P8121). It is also possible to use paper whose surface is coated and whose color density and resolving power are improved, and paper whose corona discharge treatment has been applied to the base paper described in Japanese Patent Application Laid-Open No. 59-35985 to improve coating suitability.

  Further, the synthetic resin film used as the support is not deformed by heating during the development process, and can be arbitrarily selected from known materials having dimensional stability. Examples of such a film include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate film, polystyrene films, polypropylene films, polyolefin films such as polyethylene, and the like. These can be used alone or in combination. The thickness of the support is preferably 20 to 200 μm.

<Protective layer>
In the heat-sensitive recording material of the present invention, if necessary, the heat-sensitive recording layer is used for the purpose of preventing sticking or head contamination when printing with a thermal head on the heat-sensitive recording layer or imparting water resistance to the recording material. It is preferable to further provide a protective layer containing polyvinyl alcohol or the like as a main component and added with various pigments, release agents and the like.

<Print record>
When the recording surface of the heat-sensitive recording material of the present invention thus obtained is heated with a thermal head or the like, the capsule wall such as polyurea or polyurethane is softened, and the coupler outside the capsule enters the capsule and develops color. After recording, irradiation with light having an absorption wavelength of the diazonium salt compound causes the diazonium salt compound to decompose and lose reactivity with the coupler, so that the image is fixed.

  As a fixing light source, various fluorescent lamps, xenon lamps, mercury lamps, and the like are used. It is preferable that this emission spectrum substantially coincides with the absorption spectrum of the diazonium salt compound used in the recording material, since it can be efficiently photofixed. In addition, the heat-sensitive recording material of the present invention can be exposed using a manuscript, decompose a diazonium salt compound other than the image forming portion to form a latent image, and then heat and develop the recording material to obtain an image. You can also.

<Multicolor thermal recording material>
The heat-sensitive recording material of the present invention is any one of a monochromatic heat-sensitive recording material having one heat-sensitive recording layer on a support and a multi-color heat-sensitive recording material having a heat-sensitive recording layer having a laminated structure in which a plurality of single-color recording layers are laminated. It may be. In the case of a multicolor heat-sensitive recording material, at least one recording layer may be the heat-sensitive recording layer according to the present invention (the heat-sensitive recording layer satisfying the requirements of the first invention or the second invention).

In particular, in the case of a full-color heat-sensitive recording layer including a cyan coloring layer, a yellow coloring layer, and a magenta coloring layer, all three layers on the support are composed of diazo color formers, or the first close to the support. The heat-sensitive recording layer of the first 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. Thermosensitive recording materials are preferred. The heat-sensitive recording material of the present invention preferably has a structure in which a cyan color-developing layer, a magenta color-developing layer, and a yellow color-developing layer are laminated in this order from the support side. Any layer can be used.
An example of the multicolor thermosensitive recording material is shown below.

  On a support, a recording layer containing an electron-donating dye and an electron-accepting compound (first recording layer (A layer)), a diazonium salt compound having a maximum absorption wavelength of 365 ± 30 nm, and the diazonium salt compound react A photofixable recording layer (second recording layer (B layer)) containing a colored coupler, a diazonium salt compound having a maximum absorption wavelength of 445 ± 50 nm, and a coupler that reacts with the diazonium salt compound to develop a color And a light-fixing type recording layer (third recording layer (C layer)), and a recording layer formed by laminating in this order. A recording material provided with a layer.

Next, a recording method of this multicolor thermosensitive recording material will be described.
First, the third recording layer (C layer) is heated to cause the diazonium salt compound and coupler contained in the layer to develop color. Next, after irradiation with light having an emission center wavelength of 430 ± 30 nm to decompose and photofix the unreacted diazonium salt compound contained in the C layer, the second recording layer (B layer) is sufficiently colored. The heat is applied to cause the diazonium salt compound and coupler contained in the layer to develop color. At this time, the C layer is also strongly heated at the same time, but the diazonium salt compound has already been decomposed (photofixed) and does not develop color because it loses its coloring ability. Furthermore, after irradiating with light having an emission center wavelength of 360 ± 20 nm, the diazonium salt compound contained in the B layer is decomposed and photofixed, and finally, the first recording layer (A layer) has sufficient heat to develop color. Add color. At this time, the recording layers of the C layer and the B layer are also strongly heated at the same time. However, since the diazonium salt compound has already been decomposed and the coloring ability is lost, no color is developed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

[Example 1]
(1) Preparation of thermal recording layer coating solution (a) <Preparation of phthalated gelatin aqueous solution>
Phthalated gelatin (trade name: MGP gelatin, manufactured by Nippi Collagen Co., Ltd.) 32 parts, 1,2-benzothiazolin-3-one (3.5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd.) 0.9143 Part 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-treated gelatin aqueous solution>
25.5 parts of alkali-treated low ion gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industry Co., Ltd.) )) 0.7286 parts, calcium hydroxide 0.153 parts, and ion-exchanged water 143.6 parts were mixed and dissolved at 50 ° C. to obtain an alkali-treated gelatin aqueous solution for preparing an emulsion.

<Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)>
To 16.1 parts of ethyl acetate, 4.4 parts of the following diazonium salt compound (A) (I / O value of Ar portion: 0.45), 4.8 parts of monoisopropylbiphenyl, 4.8 parts of diphenyl phthalate, and diphenyl -0.4 part of (2,4,6-trimethylbenzoyl) phosphine oxide (trade name: Lucillin TPO, manufactured by BASF Japan Ltd.) was added and heated to 40 ° C. to dissolve uniformly. Mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material (trade name: Takenate D119N (50% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) 8.6 parts was added and stirred uniformly to obtain a mixture (I).

Separately, 16.3 parts of ion-exchanged water and 0.34 part of Scraph AG-8 (50%; manufactured by Nippon Seika Co., Ltd.) were added to 58.6 parts of the phthalated gelatin aqueous solution to obtain a mixture (II) It was.
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.). After adding 20 parts of water to the obtained emulsion and homogenizing it, the mixture was stirred at 40 ° C. to carry out an encapsulation reaction for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corp.) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content concentration of the capsule liquid was 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (a). The obtained microcapsules had a median diameter of 0.36 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.).

<Preparation of coupler compound emulsion (a)>
33.0 parts of ethyl acetate and 5.7 parts of the following coupler compound (C) and 4,4 ′-(m-phenylenediisopropylidene) diphenol (trade name: Bisphenol M (manufactured by Mitsui Chemicals)) 5 .2 parts, 15.6 parts tricresyl phosphate, 3,3,3 ′, 3′-tetramethyl-5,5 ′, 6,6′-tetra (1-propyloxy) -1,1′-spirobis 3.3 parts of indane, 13.6 parts of 4- (2-ethylhexyloxy) benzenesulfonic acid amide (manac), 6.8 parts of 4-n-pentyloxybenzenesulfonic acid amide (manac) And 4.2 parts of calcium dodecylbenzenesulfonate (trade name: Pionein A-41-C, 70% methanol solution, Takemoto Yushi Co., Ltd.) were dissolved to obtain a mixed liquid (III).

Separately, 107.3 parts of ion-exchanged water was mixed with 206.3 parts of the alkali-treated gelatin aqueous solution to obtain a mixed liquid (IV).
The mixed solution (III) was added to the mixed solution (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 content concentration was 26.5%. The particle size of the obtained coupler compound emulsion was 0.21 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).
Furthermore, 9 parts of SBR latex (trade name SN-307, 48% solution, manufactured by Sumika Aves Latex Co., Ltd.) with a concentration adjusted to 26.5% are added to 100 parts of the coupler compound emulsion. The mixture was stirred uniformly to obtain a coupler compound emulsion (a).

<Preparation of thermosensitive recording layer coating solution (a)>
The diazonium salt compound-encapsulated microcapsule liquid (a) and the coupler compound emulsion liquid (a) are mixed so that the molar ratio of the encapsulated coupler compound / diazonium salt compound is 2.8 / 1, and thermal recording is performed. A layer coating solution (a) was obtained.

(2) Preparation of coating solution for light transmittance adjusting layer -Preparation of UV absorber precursor microcapsule solution-
209 parts of ethyl acetate, 37 parts of [2-allyl-6- (2H-benzotriazol-2-yl) -4-t-octylphenyl] benzenesulfonate as a UV absorber precursor, 2,2′-t-octyl Hydroquinone 12.7 parts, tricresyl phosphate 4.8 parts, α-methylstyrene dimer (trade name: MSD-100, manufactured by Mitsui Chemicals, Inc.) 15.1 parts, calcium dodecylbenzenesulfonate (trade name Pionein A-41) 1.8 parts of -C (70% methanol solution, Takemoto Yushi Co., Ltd.) were dissolved and dissolved uniformly. 74.5 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.)) as a capsule wall material was added to the mixed solution and stirred uniformly. An ultraviolet absorber precursor mixture (V) was obtained.

  Separately, 30 parts of itaconic acid-modified polyvinyl alcohol (trade name: KL-318, manufactured by Kuraray Co., Ltd.) 83.4 parts, silica-modified polyvinyl alcohol (trade name: R-1130, manufactured by Kuraray Co., Ltd.) 46.9 parts. A 14.3% part phosphoric acid aqueous solution and 1685 parts ion-exchanged water were mixed to prepare a PVA aqueous solution for an ultraviolet absorber precursor microcapsule solution.

  The ultraviolet absorber precursor mixed solution (V) is added to 1530 parts of the PVA aqueous solution for the ultraviolet absorber precursor microcapsule solution, and emulsified and dispersed at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). did. After adding 300 parts of ion exchange water to the obtained emulsion and homogenizing it, an encapsulation reaction was carried out for 3 hours with stirring at 40 ° C. Thereafter, 830 parts of ion exchange resin Amberlite MB-3 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid concentration of the capsule liquid was 13%. The obtained microcapsules had a median diameter of 0.3 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.). In 1244 parts of this capsule liquid, 20.6 parts of colloidal silica (trade name: Snowtex OL (20% aqueous solution), manufactured by Nissan Chemical Industries, Ltd.), carboxy-modified styrene butadiene latex (trade name: SN-307, (48 % Aqueous solution) and 3.4 parts of Sumitomo Nougatac Co., Ltd.) were mixed to obtain an ultraviolet absorber precursor microcapsule solution.

-Preparation of coating solution for light transmittance adjusting layer-
1000 parts of the ultraviolet absorber precursor microcapsule solution, 15 parts of a 4% aqueous sodium hydroxide solution, sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution) 51.36 parts were mixed to obtain a coating solution for light transmittance adjusting layer.

(3) Preparation of protective layer coating solution -Preparation of protective layer polyvinyl alcohol solution-
160 parts of vinyl alcohol-alkyl vinyl ether copolymer (trade name: EP-130, manufactured by Denki Kagaku Kogyo Co., Ltd.), mixed solution of sodium alkyl sulfonate and polyoxyethylene alkyl ether phosphate ester (trade name: Neoscore CM- 57. (54% aqueous solution), manufactured by Toho Chemical Co., Ltd.) 8.74 parts and 3832 parts of ion-exchanged water were mixed and dissolved at 90 ° C. for 1 hour to obtain a uniform polyvinyl alcohol solution for a protective layer. It was.

-Preparation of pigment dispersion for protective layer-
Barium sulfate (trade name: BF-21F, barium sulfate content 93% or more, manufactured by Sakai Chemical Industry Co., Ltd.) 8 parts anionic special polycarboxylic acid type polymer activator (trade name: Poise 532A (40% Aqueous solution), produced by Kao Co., Ltd.) 0.2 parts and ion-exchanged water 11.8 parts were mixed and dispersed in a dynomill to prepare a pigment dispersion for protective layer. As a result of particle size measurement (LA-910, manufactured by HORIBA, Ltd.), this dispersion liquid had a median diameter of 0.20 μm or less.
To 45.6 parts of the barium sulfate dispersion, 8.1 parts of colloidal silica (trade name: Snowtex O (20% aqueous solution), manufactured by Nissan Chemical Industries, Ltd.) was added to obtain the desired dispersion. .

-Preparation of matting agent dispersion for protective layer-
An aqueous dispersion of 1-2 benzisothiazoline 3-one (trade name: PROXEL BD, manufactured by ICI Co., Ltd.) in 220 parts of wheat starch (trade name: wheat starch S, manufactured by Shinshin Foods Industries Co., Ltd.) ) 3.81 parts and 1976.19 parts of ion exchange water were mixed and dispersed uniformly to obtain a protective layer matting agent dispersion.

-Preparation of coating blend liquid for protective layer-
To 1000 parts of the polyvinyl alcohol solution for the protective layer, 40 parts of a fluorosurfactant (trade name: Megafac F-120, 5% aqueous solution, manufactured by Dainippon Ink & Chemicals, Inc.), (4-nonylphenoxytrioxy) 50 parts of ethylene) sodium butylsulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution), 59.87 parts of the pigment dispersion for the protective layer, 16.65 parts of the matting agent dispersion for the protective layer, stearin 48.7 parts of zinc acid dispersion (trade name: Hyridone F115, 20.5% aqueous solution, manufactured by Chukyo Yushi Co., Ltd.) and 280 parts of ion-exchanged water were uniformly mixed to obtain a coating solution for a protective layer.

(4) Preparation of support -Preparation of coating solution for undercoat layer-
40 parts of enzyme-degraded gelatin (average molecular weight: 10,000, PAGI viscosity: 15 mP, PAGI jelly strength: 20 g) was added to 60 parts of ion-exchanged water and dissolved by stirring at 40 ° C. to prepare a gelatin aqueous solution for an undercoat layer.
Separately, 8 parts of water-swelling synthetic mica (aspect ratio: 1000, trade name: Somasif ME100, manufactured by Co-op Chemical Co.) and 92 parts of water were mixed and then wet-dispersed with Viscomil, and the average particle size was 2.0 μm. A mica dispersion was obtained. Water was added to the mica dispersion so that the mica concentration was 5%, and the mixture was uniformly mixed to prepare a desired mica dispersion.
Next, 120 parts of water and 556 parts of methanol are added to 100 parts of the 40% gelatin aqueous solution at 40 ° C. and sufficiently stirred and mixed, and then 208 parts of the 5% mica dispersion is added and sufficiently stirred and mixed. 9.8 parts of 66% polyethylene oxide surfactant was added. The liquid temperature was kept between 35 ° C. and 40 ° C., and 7.3 parts of an epoxy compound gelatin hardener (manufactured by Nagase Kasei Kogyo Co., Ltd., Denacol EX80) was added, and an undercoat layer coating solution (5.7%) was added. Prepared.

-Production of support with undercoat layer-
Wood pulp composed of 100 parts of one or more kinds of LBKP (hardwood bleached kraft pulp) is beaten to 300 cc Canadian freeness with a disc refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 1. aluminum sulfate 0 parts, 0.1 parts of polyamide polyamine epichlorohydrin and 0.5 parts of cationic polyacrylamide were added at an absolutely dry mass ratio with respect to the pulp, and paper was made with a long paper machine, and both sides of the base paper were calcium chloride with a size press. A polyvinyl alcohol solution containing a water-soluble fluorescent whitening agent was applied, a base paper having a basis weight of 114 g / m ² was made, and the thickness was adjusted to 100 μm by a calendar process.
Next, after corona discharge treatment was performed on both sides of the base paper, polyethylene was coated to a resin thickness of 36 μm using a melt extruder to form a matte resin layer (this surface is called the back surface). Next, using a melt extruder on the side opposite to the surface on which the resin layer is formed, a 10% anatase-type titanium dioxide and a polyethylene containing a trace amount of ultramarine are coated to a resin thickness of 50 μm, and a resin having a glossy surface. A layer was formed (this face is called the front face). After the corona discharge treatment is applied to the polyethylene resin-coated surface of the back surface, aluminum oxide (trade name; alumina sol 100, manufactured by Nissan Chemical Industries, Ltd.) / Silicon dioxide (trade name; Snowtex O, Nissan Chemical Industries ( Co., Ltd.) = 1/2 (mass ratio) was dispersed in water and applied in an amount of 0.2 g / m ² after drying. Next, the polyethylene resin-coated surface on the front side was subjected to a corona discharge treatment, and then the undercoat layer coating solution was kept at 40 ° C., coated with a slanted gravure roll 100 mesh, and dried. The coating amount before drying at that time was 12.5 g / m ² .

(5) Application of coating solution for heat-sensitive recording layer From the bottom, the coating solution for heat-sensitive recording layer (a), the coating solution for light transmittance adjusting layer, and the coating solution for protective layer are applied in this order on the surface of the support. Three layers were applied simultaneously and dried under conditions of 30 ° C. and 30% humidity to obtain a heat-sensitive recording material of Example 1.
At this time, the coating amount of the thermosensitive recording layer coating solution (a) was adjusted so that the coating amount of the diazonium salt compound (A) contained in the solution was 0.3 mmol in terms of solid coating amount, and the light transmittance was adjusted. The adjustment layer coating solution was applied such that the solid content was 2.35 g / m ² , and the protective layer coating solution was 1.39 g / m ² .

[Example 2]
In Example 1, the diazonium salt compound (A) used in <Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)> was used in an equimolar amount of the following compound (A-2) (Ar portion I / O value: A heat-sensitive recording material of Example 2 was obtained in the same manner as in Example 1 except that 0.48) was used.

[Example 3]
In Example 1, the diazonium salt compound (A) used in <Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)> was used in an equimolar amount of the following compound (A-3) (I / O value of Ar moiety: A heat-sensitive recording material of Example 3 was obtained in the same manner as Example 1 except that 0.50) was used.

[Comparative Example 1]
In Example 1, the diazonium salt compound (A) used in <Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)> was used in an equimolar amount of the following compound (A-4) (Ar portion I / O value: A heat-sensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that it was replaced with 0.52).

[Comparative Example 2]
In Example 1, the diazonium salt compound (A) used in <Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)> was used in an equimolar amount of the following compound (A-5) (I / O value of Ar moiety: A heat-sensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that it was replaced with 0.52).

[Comparative Example 3]
In Example 1, except that the coupler compound (C) used in <Preparation of coupler compound emulsion (a)> was replaced by an equimolar amount of the following compound (C-2) (pKa: 11.1). In the same manner as in Example 1, a heat-sensitive recording material of Comparative Example 3 was obtained.

≪Evaluation≫
The following evaluation was performed on the heat-sensitive recording materials of the examples and comparative examples.

<Color development test>
The thermal recording materials of Examples 1 to 3 and Comparative Examples 1 and ² were printed with a thermal head manufactured by Kyocera so that the thermal recording material was 52 mJ / mm ^2. The density after 6 seconds after printing and the density after 600 seconds were expressed as X− Measured with Rite310RD, the increase rate was calculated from both concentrations. The results are shown in Table 1.

<Hue evaluation>
The heat-sensitive recording materials of Example 1 and Comparative Example 3 were printed by the same method as in the color development test, and the reflection spectrum of the image area was measured with a spectrophotometer (manufactured by JASCO Corporation, trade name: V-570). The wavelength width (half width) until the absorbance was reduced to 1/2 on the long wave side from λmax of dye absorption in the image area was determined.

From Table 1 above, in the heat-sensitive recording materials of Examples 1 to 3, the increase in the color density after 600 seconds was as good as 10% or less after 6 seconds, and the desired density was obtained in a short time. On the other hand, it can be seen that the heat-sensitive recording materials of Comparative Examples 1 and 2 have a sharp increase in density, and a desired density cannot be obtained in a short time.
Further, from Table 2 above, the heat-sensitive recording material of Example 1 using a non-dissociative coupler has a narrower half-value width than the heat-sensitive recording material of Comparative Example 3 using a dissociative coupler, and dye absorption in the image area. It is clear that a sharp hue is obtained.

Claims (3)

A heat-sensitive recording material having a recording layer comprising a non-dissociative coupler on a support and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, 6 seconds after printing A heat-sensitive recording material, wherein the color density increase rate after 600 seconds after printing is 10% or less with respect to the color density.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ] A thermosensitive recording material having a recording layer comprising a non-dissociative coupler on a support and a diazonium salt compound represented by the following general formula (1) encapsulated in a microcapsule, wherein the general formula (1 A heat-sensitive recording material, wherein the Ar portion of the diazonium salt compound represented by formula (I) has an I / O value of 0.50 or less.

[In the general formula (1), Ar represents an aryl group, and X ⁻ represents an anion. ] The heat-sensitive recording material according to claim 2, wherein the diazonium salt compound represented by the general formula (1) is represented by the following general formula (2) or (3).

[In the general formula (2), R ²¹ represents a hydrogen atom, an alkyl group, or an aryl group. R ²² represents an alkyl group or an aryl group. R ²³ , R ²⁴ , R ²⁵ and R ²⁶ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ²³ , R ²⁴ , R ²⁵ and R ²⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion. ]

[In the general formula (3), R ¹ and R ² each independently represents an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group or a carbamoyl group, and R ¹ and R ² are bonded to each other to form a ring. It may be formed. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, halogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group or -N ₂ ⁺ X ^- represents a. However, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion. ]