JP2006035739A - Recording material and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording material having a high sensitivity and excelling in thermal stability in darkness. <P>SOLUTION: In a manufacturing method of the recording material wherein a solution containing a diazonium salt compound and a coupler solution containing a coupler developing color in reaction with the diazonium salt compound are applied on a substrate, the coupler solution is obtained by dissolving the coupler in an ionic liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a recording material capable of stably emulsifying and dispersing a coupler, and a recording material obtained by this production method and having excellent image light resistance and image fixability.

  The diazo compound reacts with a compound called a coupler such as a phenol derivative or a compound having an active methylene group to form an azo dye. Decomposes by light irradiation and loses its activity. Using this property, diazo compounds have been used for a long time as optical recording materials represented by diazocopy (see Non-Patent Document 1).

  Recently, it is also applied to recording materials that require image fixing. As a typical example, a diazo compound and a coupler are heated in accordance with an image signal, reacted to form an image, and then irradiated with light to fix the image. A photo-fixing type thermal recording material has been proposed (for example, see Non-Patent Document 2).

  However, these recording materials have a drawback that the shell life as a recording material is short because the diazo compound gradually decomposes and loses reactivity even in a dark place. In order to remedy this drawback, a method has been proposed in which a diazo compound is encapsulated in a microcapsule and the diazo compound is isolated from a substance that promotes decomposition such as water or base. This method makes it possible to dramatically improve the shelf life as a recording material (see Non-Patent Document 3).

A microcapsule having a glass transition temperature higher than room temperature can be used as a thermoresponsive microcapsule as a thermoresponsive microcapsule because the capsule wall at room temperature is non-permeable to matter, but is permeable to substances above the glass transition temperature. . That is, the recording material in which a thermoresponsive microcapsule containing a diazo compound and a thermosensitive recording layer containing a coupler and a base are coated on the support can be used to (1) stably hold the diazo compound for a long period of time. (2) Colored image formation by heating and (3) Imaging by light irradiation are possible.
In such a heat-sensitive recording material, a high-functionality such as a recording material that forms a multicolor image line (see Patent Documents 1 and 2) has been achieved. It is desired to improve performance such as excellent hue and light resistance and image fixability of an image area.

  On the other hand, ionic liquids have attracted attention in recent years. Ionic liquids are characterized by being chemically stable, having almost no vapor pressure and relatively low viscosity, and are considered to be environmentally useful as solvents that can be recovered in organic synthesis reactions. Considering the characteristics of the ionic liquid, it can be expected that it can be used as an oil droplet component when emulsified and dispersed. Examples of using an ionic liquid for a recording material include Patent Documents 3 and 4, which disclose an example of using it for a silver salt photothermographic color photosensitive material.

  In the direct thermal recording material, the recording layer instantaneously becomes a high temperature of about 200 ° C. due to the dynamic energy given by the thermal head. In such a recording material, the utility of the chemical stability and low vapor pressure property of the ionic liquid can be expected. However, an example in which an ionic liquid is directly applied to a thermosensitive recording material is not disclosed.

Patent Document 5 discloses an example in which a quaternary salt compound is used as a coupler. Quaternary salt compounds generally have low solubility and are often difficult to dissolve under normal emulsification conditions, which may be a limitation when stably emulsifying and dispersing. This specification describes emulsifying and dispersing an active hydrogen compound in the coexistence. Although the stability of the emulsified dispersion is increased by the coexistence of the active hydrogen compound, it is not sufficient and further improvement has been demanded.
As one of means for avoiding the restrictions at the time of emulsification and dispersion, structural improvement that increases the solubility of the quaternary salt compound itself can be considered. However, the introduction of a substituent that increases the solubility slows the crystallization rate of the quaternary salt compound and makes purification difficult. When a crude product is used without purification, performance such as color development and whiteness deteriorates as the purity is lowered.
Not only quaternary salt compounds but also low-solubility couplers have demanded solvents with high solubility.
JP-A-4-135787 JP-A-4-144784 US Pat. No. 6,531,270 US Pat. No. 6,531,273 JP-A-11-334217 Japan Photographic Society, “Basics of Photographic Engineering-Non-Silver Salt Photography”, Corona (1982) 89-117, 182-201 Koji Sato et al. Journal of the Institute of Image Electronics Engineers of Japan, Vol. 11 No. 4 (1982) 290-296 Tomomasa Usami et al. Journal of Electrophotographic Society, Vol. 26, No. 2 (1987), pages 115-125

  Accordingly, an object of the present invention is to stably dissolve the coupler and to emulsify and disperse it. By using the emulsified dispersion thus obtained, a high color density can be obtained, and image light fastness and image fixability are also obtained. An object is to provide a good diazo thermosensitive recording material.

As a result of intensive studies aimed at solving this problem, the present inventor has found that the coupler can be dissolved and emulsified and dispersed satisfactorily by using an ionic liquid, thereby completing the present invention.
That is, the present invention provides the following.

  <1> A method for producing a recording material, comprising: applying a coupler solution containing a diazonium salt compound-containing liquid and a coupler that reacts with the diazonium salt compound to form a color on a support; A method for producing a recording material obtained by dissolving in a liquid.

  <2> The method for producing a recording material according to <1>, wherein the coupler liquid is obtained by emulsifying and dispersing a liquid obtained by dissolving the coupler in the presence of an ionic liquid in an aqueous medium.

  <3> The ionic liquid is one or more selected from imidazolium salts, pyrazolium salts, pyridinium salts, pyrimidinium salts, pyrazinium salts, thiazolium salts, oxazolium salts, tetraalkylammonium salts and tetraalkylphosphonium salts < The manufacturing method of the recording material as described in 1> or <2>.

  <4> The method for producing a recording material according to <1>, <2> or <3>, wherein the coupler is a cationic compound.

  <5> The recording material according to <4>, wherein the cationic compound is a compound represented by the following general formula (1).

[Wherein, X and Y may be the same or different and each represents an atom selected from the group consisting of C, N, O, P and S, and X and Y are bonded via a linking group. R represents an alkyl, aryl or aralkyl group which may have a substituent. X, Y, and the linking group for linking X and Y may have a substituent, and the heterocyclic ring represented by the above formula may be further condensed with a ring. A ⁻ represents a counter anion. ]

  <6> In a recording material having a microcapsule encapsulating a diazonium salt compound on a support and a coupler that develops color by reacting with the diazonium salt compound outside the microcapsule, the coupler is dissolved in an ionic liquid. A recording material characterized in that it exists.

  <7> The ionic liquid is one or more selected from imidazolium salts, pyrazolium salts, pyridinium salts, pyrimidinium salts, pyrazinium salts, thiazolium salts, oxazolium salts, tetraalkylammonium salts and tetraalkylphosphonium salts < 6> Recording material described in the above.

    According to the method of the present invention, the coupler can be stably dissolved and emulsified and dispersed. By using the emulsified dispersion thus obtained, a high color density can be obtained, and image light resistance and image fixability are also good. A diazo thermosensitive recording material can be provided.

The recording material manufacturing method of the present invention is a recording material manufacturing method in which a diazonium salt compound-containing liquid and a coupler liquid containing a coupler that develops color by reacting with the diazonium salt compound are coated on a support, A coupler liquid is obtained by dissolving a coupler in an ionic liquid.
Hereinafter, this method will be described in detail.

-Ionic liquid-
In the present invention, the “ionic liquid” means, as a structural feature, a substance composed of a cation made of an organic compound containing a hetero atom and an anion formed by dissociation of an inorganic acid, an organic acid or the like. For details on ionic liquids, see "Ionic liquids-the forefront and future of development" (supervised by Hiroyuki Ohno, CM Publishing (2003)).

  In the present invention, any ionic liquid satisfying the above definition can be used without particular limitation. From the viewpoint of compatibility with an organic compound such as a coupler used in the present invention, imidazolium salt, pyrazolium salt, pyridinium salt , A pyrimidinium salt, a pyrazinium salt, a thiazolium salt, an oxazolium salt, a tetraalkylammonium salt, and a tetraalkylphosphonium salt, preferably an imidazolium salt, a pyridinium salt, or a tetraalkylammonium salt. Particularly preferred are imidazolium salts.

  Moreover, the ionic liquid which can be used suitably for this invention can be represented by following General formula (3) to (5).

[In General Formula (3), R ²¹ and R ²² each independently represents an alkyl group having 1 to 30 carbon atoms. R ²³ , R ²⁴ and R ²⁵ each independently represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 10 carbon atoms. The alkyl group represented by R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ may be substituted with a halogen atom, aryl group, alkoxy group, aryloxy group, alkoxycarbonyl group, or acyloxy group. Y- represents a counter anion. ]

[In General Formula (4), R ²⁶ represents an alkyl group having 1 to 30 carbon atoms. R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ each independently represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 10 carbon atoms. The alkyl group represented by R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ is substituted with a halogen atom, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, or an acyloxy group. Also good. Y- represents a counter anion. ]

[In General Formula (5), R ³² , R ³³ , R ³⁴ and R ³⁵ each independently represents an alkyl group having 1 to 30 carbon atoms. R ³² , R ³³ , R ³⁴ and R ³⁵ may be substituted with a halogen atom, aryl group, alkoxy group, aryloxy group, alkoxycarbonyl group or acyloxy group. Z represents a nitrogen atom or a phosphorus atom. Y- represents a counter anion. ]

In general formula (3), R ²¹ and R ²² each independently represents an alkyl group having 1 to 30 carbon atoms. From the viewpoint of compatibility with the compound contained in the thermosensitive recording layer. In general formula (3), it is preferable that any one of R ²¹ and R ²² is an alkyl group having 1 to 4 carbon atoms, and it is particularly preferable that either one is a methyl group.
In the general formula (3), the alkyl group having 1 to 30 carbon atoms represented by R ²¹ and R ²² is preferably an alkyl group having 1 to 20 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, isopropyl group, n-butyl group, isopentyl group, 3-pentyl group, t-amyl group, n-hexyl group, cyclohexyl group, n-octyl group, and t-octyl group. , 2-ethylhexyl group, isononyl group, n-dodecyl group, n-tetradecyl group, hexadecyl group, n-octadecyl group and the like, and methyl group, n-octyl group, n-dodecyl group and n-tetradecyl group are preferable. .

In the general formula (3), the alkyl group having 1 to 30 carbon atoms represented by R ²¹ and R ²² may further have a substituent. As such a substituent, an aryl group is mentioned as a preferred group. Examples of the substituted alkyl group include a benzyl group, an α-methylbenzyl group, a phenethyl group, and a (2-pyridinyl) methyl group, and an α-methylbenzyl group is preferable.

In general formula (3), R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms.
Examples of the halogen atom represented by R ^{23 to} R ²⁵ in the general formula (3) include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and among them, a fluorine atom and a chlorine atom are preferable.

In the general formula (3), the alkyl group having 1 to 10 carbon atoms represented by R ^{23 to} R ²⁵ is preferably an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, isopropyl group, n-butyl group, isopentyl group, 3-pentyl group, t-amyl group, n-hexyl group, cyclohexyl group, n-octyl group, and t-octyl group. , 2-ethylhexyl group, isononyl group, n-dodecyl group, hexadecyl group and the like, and methyl group, ethyl group and isopropyl group are preferable.

The (substituted) alkyl group represented by R ^{21 to} R ²⁵ may be further substituted with a substituent. As the substituent, a halogen atom, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, or an acyloxy group is preferable.

The counter anion represented by Y ⁻ in the general formula (3) may be either an inorganic anion or an organic anion.
Preferred examples of the inorganic anion include hexafluorophosphate ion, tetrafluoroborate ion, trifluoromethanesulfonate ion, bis (trifluoromethanesulfone) imide ion, and the like. Hexafluorophosphate ion or bis (trifluoromethanesulfone) ) Imide ions are particularly preferred.
As the organic anion, polyfluoroalkylcarboxylic acid ions, polyfluoroalkylsulfonic acid ions, arylcarboxylic acid ions, arylsulfonic acid ions, or ions described in the specification of Japanese Patent Application No. 2002-108919 are preferable. Fluoroalkylcarboxylate ions, polyfluoroalkylsulfonate ions, or ions described in the specification of Japanese Patent Application No. 2002-108919 are particularly preferred.

In General Formula (4), R ²⁶ represents an alkyl group having 1 to 30 carbon atoms.
The alkyl group having 1 to 30 carbon atoms represented by R ²⁶ in the general formula (4) is synonymous with the alkyl group represented by R ²¹ or R ²² in the general formula (3), and preferred embodiments thereof are also the same. .

In the general formula (4), R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms.
In the general formula (4), the halogen atom represented by R ^{27 to} R ³¹ and the alkyl group having 1 to 10 carbon atoms are the same as the halogen atom and the alkyl group represented by R ^{23 to} R ²⁵ in the general formula (3). It is synonymous and a preferable aspect is also the same.

The alkyl group represented by R ^{26 to} R ³¹ may be substituted with a substituent. As the substituent, a halogen atom, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, or an acyloxy group is preferable.

The counter anion represented by Y ⁻ in the general formula (4) is synonymous with the counter anion represented by Y ⁻ in the general formula (3), and the preferred embodiment is also the same.

In the general formula (5), R ³² , R ³³ , R ³⁴ and R ³⁵ represent an alkyl group having 1 to 30 carbon atoms.
The alkyl group having 1 to 30 carbon atoms represented by R ^{32 to} R ³⁵ in the general formula (5) is synonymous with the alkyl group represented by R ²¹ or R ²² in the general formula (3). It is the same.

The alkyl group represented by R ^{32 to} R ³⁵ may be substituted with a substituent. As the substituent, a halogen atom, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, or an acyloxy group is preferable.

  In General formula (5), Z represents a nitrogen atom or phosphorus, and a nitrogen atom is preferable.

The counter anion represented by Y ⁻ in the general formula (5) is synonymous with the counter anion represented by Y ⁻ in the general formula (3), and the preferred embodiment is also the same.

  Specific examples of the ionic liquid in the present invention (Exemplary Compounds I-1 to I-56) are shown below, but the present invention is not limited thereto.

  The amount of the ionic liquid used is preferably in the range of 0.05 to 5 g, particularly preferably in the range of 0.2 to 2 g, with respect to 1 g of the coupler.

-Coupler-
Next, couplers (coupling components) that can be used in the recording material of the present invention and the manufacturing method thereof will be described.
As the coupler, any compound can be used as long as it forms a dye by coupling with a diazonium salt compound in a basic atmosphere and / or a neutral atmosphere. All so-called 4-equivalent coupler compounds for silver halide photographic light-sensitive materials can be used as couplers. A part of a 2-equivalent coupler can also be used. These can be selected according to the target hue.
For example, there are so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives and the like, and they are used within a range meeting the purpose of the present invention.

  The details of the coupler are described in JP-A-4-201483, JP-A-7-223367, JP-A-7-223368, JP-A-7-323660, JP-A-7-125446, JP-A-7-96671, JP-A-7-167671. JP-A-7-223367, JP-A-7-223368, JP-A-9-156229, JP-A-9-216468, JP-A-9-216469, JP-A-9-203472, JP-A-9-319025, JP-A-10 -35113, JP-A-10-193801, JP-A-10-264532, and the like.

Among the above, in the present invention, a compound represented by the following general formula (6) or a tautomer thereof is preferable.
Hereinafter, the coupler represented by the general formula (6) will be described in detail.

  In the general formula (6), E1 and E2 each independently represent an electron-withdrawing group, and L represents a group that can be separated when azo coupling to form an azo dye. E1 and E2 may combine to form a ring.

  The electron-withdrawing group represented by E1 and E2 means a substituent having a positive Hammett σp value, which may be the same or different. For example, an acetyl group, a propionyl group, Pivaloyl group, chloroacetyl group, trichloroacetyl group, trifluoroacetyl group, 1-methylcyclopropylcarbonyl group, 1-ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group, tenoyl Acyl groups such as methoxycarbonyl groups, ethoxycarbonyl groups, 2-methoxyethoxycarbonyl groups, 4-methoxyphenoxycarbonyl groups, etc .; carbamoyl groups, N, N-dimethylcarbamoyl groups, N, N-diethylcarbamoyl groups Group, N-phenylcarbamoyl group Carbamoyl groups such as N- [2,4-bis (pentyloxy) phenyl] carbamoyl group, N- [2,4-bis (octyloxy) phenyl] carbamoyl group, morpholinocarbonyl group; methanesulfonyl group, benzenesulfonyl group Alkylsulfonyl group such as toluenesulfonyl group or arylsulfonyl group; phosphono group such as diethylphosphono group; benzoxazol-2-yl group, benzothiazol-2-yl group, 3,4-dihydroquinazolin-4-one- Preferred examples include a heterocyclic group such as a 2-yl group and a 3,4-dihydroquinazolin-4-sulfon-2-yl group; a heterocyclic group; a nitro group; an imino group; and a cyano group.

  Further, the electron-withdrawing groups represented by E1 and E2 may be bonded to form a ring. The ring formed by E1 and E2 is preferably a 5- to 6-membered carbocyclic or heterocyclic ring.

  L in the general formula (6) represents a group capable of leaving during azo coupling. The leaving group L includes a halogen atom (fluorine, bromine, chlorine, iodine), a substituted alkyl group (hydroxymethyl group, dimethylaminomethyl group). ), Alkylthio group (for example, ethylthio group, 2-carboxyethylthio group, dodecylthio group, 1-carboxydodecylthio group), arylthio group (for example, phenylthio group, 2-butoxy-t-octylphenylthio group), alkoxyl group (For example, ethoxy group, dodecyloxy group, methoxyethylcarbamoylmethoxy group, carboxypropyloxy group, methylsulfonylethoxy group, ethoxycarbonylmethoxy group), aryloxy group (for example, 4-methylphenoxy group, 4-chlorophenoxy group, 4-methoxyphenoxy group, 4 Carboxyphenoxy group, 3-ethoxycarboxyphenoxy group, 3-acetylaminophenoxy group, 2-carboxyphenoxy group), acyloxy group (for example, acetoxy group, tetradecanoyloxy group, benzoyloxy group), arylsulfonyloxy group (for example, , Toluenesulfonyloxy group), dialkylaminocarbonyloxy group (for example, dimethylaminocarbonyloxy group, diethylaminocarbonyloxy group), diarylaminocarbonyloxy group (for example, diphenylaminocarbonyloxy group), alkoxycarbonyloxy group (for example, ethoxy Carbonyloxy group, benzyloxycarbonyloxy group), aryloxycarbonyloxy group (for example, phenoxycarbonyloxy group), or heterocyclic group (for example, , Imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group).

  Specific examples of the coupler represented by the general formula (6) are shown below, but the present invention is not limited thereto. The following tautomers of couplers can also be mentioned as suitable.

  The tautomer of the coupler is one that exists as an isomer of the coupler represented by the above, and has a relationship in which the structure easily changes between the two. The coupler used in the present invention As such, the tautomer is also preferable.

The coupler used in the present invention is particularly preferably a cationic compound, and more preferably a compound represented by the general formula (1). In the quaternary salt heterocyclic compound represented by the general formula (1), R is preferably an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. The alkyl group may be branched or have an unsaturated bond in the chain. In the case where the alkyl group of R of the compound represented by the general formula (1) and the aryl group have a substituent, the substituent is an alkoxy group, an aryl group, an aryloxy group, an alkylthio group, an arylthio group, an alkoxycarbonyl group, An acyloxy group, an alkyloxycarbonyloxy group, an aryloxycarbonyloxy group, a carboxyl group, an alkylsulfonyl group, an arylsulfonyl group and a halogen atom are preferred. Examples of the atomic group constituting the linking group for linking X and Y include carbon and nitrogen. Moreover, in the said formula, the coupling group which connects X, Y, and X and Y may have a substituent. Examples of these substituents include alkyl groups, aryl groups, alkylthio groups, arylthio groups, and substituted amino groups. Further, the heterocyclic ring represented by the general formula (1) may be further condensed with a ring such as a benzene ring, and the ring may be a heterocyclic ring. The counter anion represented by A- may be anything as long as it can form a counter anion, but Cl-, Br-, I-, a sulfonic acid anion having 1 to 20 carbon atoms, and a carboxylic acid having 2 to 21 carbon atoms. Anions, alkyl sulfate ions, PF ₆ ⁻ , BF ₄ − and the like are preferable. The substituent which R has may be substituted for the counter anion represented by A −, and in this case, it takes the form of an inner salt. Among the heterocycles represented by the following general formula (2),

As specific heterocycles, those shown below are preferable.

  Of the heterocycles represented by the above formula, the number of heteroatoms (N atom, O atom, P atom, S atom, etc.) in the same ring is 2 or more from the viewpoint of showing good coupling activity. Three or more are preferable, and among them, a triazole ring and a tetrazole ring are particularly preferable. Specific examples of the coupler according to the present invention are shown below, but the present invention is not limited thereto.

  The coupler represented by the general formula (1) can be synthesized by the method described in JP-A-11-334217.

-Diazo compounds-
The diazo compound used in the present invention is a compound represented by the following general formula Ar—N ₂ ⁺ X ⁻ [wherein Ar represents an aromatic moiety and X ⁻ represents an acid anion]. It is a compound that causes a coupling reaction to develop color and decomposes by light. The maximum absorption wavelength of these can be controlled by the position and type of the substituent in the Ar portion.

  Specific examples of the diazonium forming the salt include 4- (p-tolylthio) -2,5-dibutoxybenzenediazonium, 4- (4-chlorophenylthio) -2,5-dibutoxybenzenediazonium, 4- (N , N-dimethylamino) benzenediazonium, 4- (N, N-diethylamino) benzenediazonium, 4- (N, N-dipropylamino) benzenediazonium, 4- (N-methyl-N-benzylamino) benzenediazonium, 4- (N, N-dibenzylamino) benzenediazonium, 4- (N-ethyl-N-hydroxyethylamino) benzenediazonium, 4- (N, N-diethylamino) -3-methoxybenzenediazonium, 4- (N , N-dimethylamino) -2-methoxybenzenediazonium, 4- (N-benzo) Ruamino) -2,5-diethoxybenzenediazonium, 4-morpholino-2,5-dibutoxybenzenediazonium, 4-anilinobenzenediazonium, 4- [N- (4-methoxybenzoyl) amino] -2.5- Diethoxybenzenediazonium, 4-pyrrolidino-3-ethylbenzenediazonium, 4- [N- (1-methyl-2- (4-methoxyphenoxy) ethyl) -N-hexylamino] -2-hexyloxybenzenediazonium, 4- [N- (2- (4-methoxyphenoxy) ethyl) -N-hexylamino] -2-hexyloxybenzenediazonium, 2- (1-ethylpropyloxy) -4- [di- (di-n-butylamino) Carbonylmethyl) amino] benzenediazonium, 2-benzylsulfonyl-4- [N- Chill-N-(2-octanoyloxy ethyl)] aminobenzene diazonium.

  The maximum absorption wavelength λmax of the diazo compound used in the present invention is preferably 450 nm or less, more preferably 290 to 440 nm. When the diazo compound has λmax on the longer wavelength side than the above wavelength region, it is in terms of raw preservation, and when it has λmax on the shorter wavelength side, it is image fixing property, image preservation property, hue of purple-cyan coloring in combination with a coupler. Neither is preferable in this respect. In addition, the diazo compound used in the present invention preferably has 12 or more carbon atoms, a solubility in water of 1% or less, and a solubility in ethyl acetate of 5% or more.

  Among these diazo compounds, a diazo compound represented by the following general formula (7), general formula (8), or general formula (9) is used in terms of the hue of the dye, image storage stability, and image fixability. Is more preferable.

(In the formula, Ar represents an aryl group, R ¹¹ and R ¹² each independently represents an alkyl group or an aryl group. R ¹¹ and R ¹² may be the same or different. X − represents an acid anion. .)

(Wherein R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents an alkyl group or an aryl group. R ¹⁴ , R ¹⁵ and R ¹⁶ may be the same or different. Y is a hydrogen atom or .R ¹³ showing a -OR ¹³ group is an alkyl group or an aryl group .X ^- represents an acid anion).

(In the formula, R ¹⁷ and R ¹⁸ each independently represents an alkyl group or an aryl group, and R ¹⁷ and R ¹⁸ may be the same or different. X ⁻ represents an acid anion.)

  In the general formula (7), Ar represents a substituted or unsubstituted aryl group. Examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an acyl group, and an alkoxycarbonyl group. Group, carbamoyl group, carboamide group, sulfonyl group, sulfamoyl group, sulfonamido group, ureido group, halogen group, amino group, heterocyclic group and the like, and these substituents may be further substituted.

  The substituted or unsubstituted aryl group is preferably an aryl group having 6 to 30 carbon atoms, such as a phenyl group, a 2-methylphenyl group, a 2-chlorophenyl group, a 2-methoxyphenyl group, or a 2-butoxyphenyl group. 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2 , 4,6-trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group, 3 , 4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4-dimethoxyphenyl group, 3- ( Butylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group, 4 -Aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2- Acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methylamino) -2-dodecyl Oxycarbonylphenyl groups, etc., but are not limited to these. Not. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group, or the like.

R ¹¹ and R ¹² each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. Examples of the substituent include an alkoxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a substituted amino group, and a substituted group. Examples thereof include, but are not limited to, an amide group, an aryl group, and an aryloxy group.

  The substituted or unsubstituted alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, such as a methyl group, trifluoromethyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, t -Butyl group, pentyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, t-octyl group, 2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, 4-methoxybenzyl group, tolphenylmethyl Group, ethoxycarbonylmethyl group, butoxycarbonylmethyl group, 2-ethylhexyloxycarbonylmethyl group, 2 ′, 4′-diisopentylphenyloxymethyl group, 2 ′, 4′-di-t-butylphenyloxymethyl group, Dibenzylaminocarbonylmethyl group, 2,4-di-t-a Ruphenyloxypropyl group, ethoxycarbonylpropyl group, 1- (2 ′, 4′-di-t-amylphenyloxy) propyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2 -(N, N-diethylamino) propyl group, methanesulfonylaminopropyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino) propyl group and the like are preferable. .

  Moreover, as said substituted or unsubstituted aryl group, a C6-C30 aryl group is preferable, for example, a phenyl group, 2-methylphenyl group, 2-chlorophenyl group, 2-methoxyphenyl group, 2-butoxyphenyl. Group, 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2,4,6-trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4-dimethoxyphenyl group, 3 (Dibutylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group, 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2 -Acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methylamino) -2- Examples include dodecyloxycarbonylphenyl group, but are not limited to these. Not shall. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group, or the like.

In the general formula (8), R ¹⁴ , R ¹⁵ and R ¹⁶ each represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituent include an alkyl group, an alkoxy group, and an alkylthio group. , Aryl group, aryloxy group, arylthio group, acyl group, alkoxycarbonyl group, carbamoyl group, carbamide group, sulfonyl group, sulfamoyl group, sulfonamide group, ureido group, halogen atom, amino group, heterocyclic group, etc. It is done.

  The substituted or unsubstituted alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, such as a methyl group, trifluoromethyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, t -Butyl group, benzyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, t-octyl group, 2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, 4-methoxybenzyl group, triphenylmethyl Group, ethoxycarbonylmethyl group, butoxycarbonylmethyl group, 2-ethylhexyloxycarbonylmethyl group, 2 ′, 4′-diisopentylphenyloxymethyl group, 2 ′, 4′-di-t-butylphenyloxymethyl group, Dibenzylaminocarbonylmethyl group, 2,4-di-t-a Ruphenyloxypropyl group, ethoxycarbonylpropyl group, 1- (2 ′, 4′-di-t-amylphenyloxy) propyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2 -(N, N-diethylamino) propyl group, methanesulfonylaminopropyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino) propyl group, 1-methyl A 2- (4-methoxyphenoxy) ethyl group, a di-n-butylaminocarbonylmethyl group, a di-n-octylaminocarbonylmethyl group and the like are preferable.

  Moreover, as said substituted or unsubstituted aryl group, a C6-C30 aryl group is preferable, for example, a phenyl group, 2-methylphenyl group, 2-chlorophenyl group, 2-methoxyphenyl group, 2-butoxyphenyl. Group, 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2,4,6-trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4-dimethoxyphenyl group, 3 (Dibutylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group, 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2 -Acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methylamino) -2- Dodecyloxycarbonylphenyl group, etc., but particularly limited to these Not intended to be. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group, or the like.

Y represents a hydrogen atom or an —OR ¹³ group, and in the —OR ¹³ group, R ¹³ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. Examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, a carbamide group, a sulfonyl group, a sulfamoyl group, a sulfonamide group, a ureido group, A halogen atom, an amino group, a heterocyclic group, etc. are mentioned. In terms of hue adjustment, Y is preferably a hydrogen atom or an alkyloxy group in which R ¹³ is an alkyl group.

  The substituted or unsubstituted alkyl group is preferably an alkyl group having 1 to 18 carbon atoms. For example, a methyl group, trifluoromethyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, t -Butyl group, benzyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, t-octyl group, 2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, 4-methoxybenzyl group, tolphenylmethyl Group, ethoxycarbonylmethyl group, butoxycarbonylmethyl group, 2-ethylhexyloxycarbonylmethyl group, 2 ′, 4′-diisopentylphenyloxymethyl group, 2 ′, 4′-di-t-butylphenyloxymethyl group, Dibenzylaminocarbonylmethyl group, 2,4-di-t-a Ruphenyloxypropyl group, ethoxycarbonylpropyl group, 1- (2 ′, 4′-di-t-amylphenyloxy) propyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2 -(N, N-diethylamino) propyl group, methanesulfonylaminopropyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino) propyl group and the like are preferable. .

  Moreover, as said substituted or unsubstituted aryl group, a C6-C30 aryl group is preferable, for example, a phenyl group, 2-methylphenyl group, 2-chlorophenyl group, 2-methoxyphenyl group, 2-butoxyphenyl. Group, 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2,4,6-trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4-dimethoxyphenyl group, 3 (Dibutylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group, 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2 -Acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methylamino) -2- Dodecyloxycarbonylphenyl group, etc., but particularly limited to these Not intended to be. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group, or the like.

In the general formula (9), R ¹⁷ and R ¹⁸ each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. Examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, Aryl group, aryloxy group, arylthio group, acyl group, alkoxycarbonyl group, carbamoyl group, carboamide group, sulfonyl group, sulfamoyl group, sulfonamido group, ureido group, halogen atom, amino group, heterocyclic group, etc. .

  The substituted or unsubstituted alkyl group is preferably an alkyl group having 1 to 18 carbon atoms. For example, a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, t- Butyl group, pentyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, t-octyl group, 2-ethylhexyl group, nonyl group, octadecyl group, benzyl group, 4-methoxybenzyl group, triphenylmethyl group Ethoxycarbonylmethyl group, butoxycarbonylmethyl group, 2-ethylhexyloxycarbonylmethyl group, 2 ′, 4′-diisobenthylphenyloxymethyl group, 2 ′, 4′-di-t-butylphenyloxymethyl group, Dibenzylaminocarbonylmethyl group, 2,4-di-t-amino Phenyloxypropyl group, ethoxycarbonylpropyl group, 1- (2 ′, 4′-di-t-amylphenyloxy) propyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino) propyl group, methanesulfonylaminopropyl group, acetylaminoethyl group, 2- (N, N-dimethylamino) ethyl group, 2- (N, N-diethylamino) propyl group and the like are preferable. However, it is not particularly limited to these.

  Moreover, as said substituted or unsubstituted aryl group, a C6-C30 aryl group is preferable, for example, a phenyl group, 2-methylphenyl group, 2-chlorophenyl group, 2-methoxyphenyl group, 2-butoxyphenyl. Group, 2- (2-ethylhexyloxy) phenyl group, 2-octyloxyphenyl group, 3- (2,4-di-t-pentylphenoxyethoxy) phenyl group, 4-chlorophenyl group, 2,5-dichlorophenyl group, 2,4,6, -trimethylphenyl group, 3-chlorophenyl group, 3-methylphenyl group, 3-methoxyphenyl group, 3-butoxyphenyl group, 3-cyanophenyl group, 3- (2-ethylhexyloxy) phenyl group 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 3,4-dimethoxyphenyl group, -(Dibutylaminocarbonylmethoxy) phenyl group, 4-cyanophenyl group, 4-methylphenyl group, 4-methoxyphenyl group, 4-butoxyphenyl group, 4- (2-ethylhexyloxy) phenyl group, 4-benzylphenyl group 4-aminosulfonylphenyl group, 4-N, N-dibutylaminosulfonylphenyl group, 4-ethoxycarbonylphenyl group, 4- (2-ethylhexylcarbonyl) phenyl group, 4-fluorophenyl group, 3-acetylphenyl group, 2-acetylaminophenyl group, 4- (4-chlorophenylthio) phenyl group, 4- (4-methylphenyl) thio-2,5-butoxyphenyl group, 4- (N-benzyl-N-methylamino) -2 -Dodecyloxycarbonylphenyl group, and the like. Further, these groups may be further substituted with an alkyloxy group, an alkylthio group, a substituted phenyl group, a cyano group, a substituted amino group, a halogen atom, a heterocyclic group, or the like.

In the general formula (7), the general formula (8), and the general formula (9), X ⁻ represents an acid anion, and the acid anion includes a polyfluoroalkylcarboxylic acid having 1 to 9 carbon atoms, and 1 carbon atom. To 9 polyfluoroalkylsulfonic acid, boron tetrafluoride, tetraphenylboron, hexafluorophosphoric acid, aromatic carboxylic acid, aromatic sulfonic acid and the like. In terms of crystallinity, hexafluorophosphoric acid is preferable.

Specific examples of the diazonium salt compound represented by general formula (7), general formula (8), and general formula (9) are shown below, but the present invention is not limited thereto.

  In this invention, the diazo compound represented by General formula (7), General formula (8), and General formula (9) may be used independently, and can also use 2 or more types together. Furthermore, the diazo compound represented by the general formula (7), the general formula (8), and the general formula (9) may be used in combination with an existing diazo compound according to various purposes such as hue adjustment.

The diazo compound used in the present invention is preferably contained in the thermosensitive recording layer in an amount of 0.02 to 3 g / m ² , more preferably 0.1 to ² g / m ² .

  The diazo compound used in the present invention is preferably encapsulated in microcapsules from the viewpoint of storage stability. The method of microencapsulation is not particularly limited, and microencapsulation can be performed by a conventionally known method using wall materials such as gelatin, polyurea, polyurethane, polyimide, polyester, polycarbonate, melamine and the like. Details of the microencapsulation method are described in JP-A-2-141279. In the microencapsulation, a high boiling point organic solvent may be used as a dispersion solvent for the diazo compound. The organic solvent is not particularly limited, and conventionally known ones such as alkyl phthalate, phosphate ester, citrate ester, benzoate ester, alkylamide, aliphatic ester, trimesic acid ester can be used. . Details are described in JP-A-7-17145.

  In the present invention, it is preferable to use an organic base such as tertiary amines, piperidines, piperazines, amidines, formamidines, pyridines, guanidines and morpholines for the purpose of accelerating the coupling reaction. .

  Specific examples of these organic bases include N, N′-bis (3-phenoxy-2-hydroxypropyl) piperazine, N, N′-bis [3- (p-methylphenoxy) -2-hydroxypropyl] piperazine, N, N′-bis [3- (p-methoxyphenoxy) -2-hydroxypropyl] piperazine, N, N′-bis (3-phenylthio-2-hydroxypropyl) piperazine, N, N′-bis [3- (Β-naphthoxy) -2-hydroxypropyl] piperazine, N-3- (β-naphthoxy) -2-hydroxypropyl-N′-methylpiperazine, 1,4-bis {[3- (N-methylpiperazino) -2 Piperazines such as -hydroxy] propyloxy} benzene, N- [3- (β-naphthoxy) -2-hydroxy] propylmorpholine, 1,4- Morpholines such as su [[3-morpholino-2-hydroxy) propyloxy] benzene and 1,3-bis [(3-morpholino-2-hydroxy) propyloxy] benzene, N- (3-phenoxy-2-hydroxy (Propyl) piperidine, piperidines such as N-dodecylpiperidine, triphenylguanidine, tricyclohexylguanidine, dicyclohexylphenylguanidine, 4-hydroxybenzoic acid 2-N-methyl-N-benzylaminoethyl ester, 4-hydroxybenzoic acid 2- N, N-di-n-butylaminoethyl ester, 4- (3-N, N-dibutylaminopropoxy) benzenesulfonamide, 4- (2-N, N-dibutylaminoethoxycarbonyl) phenoxyacetamide and the like can be mentioned. It is done. Details of these are described in JP-A-57-123086, JP-A-60-49991, JP-A-60-94381, JP-A-7-228731, JP-A-7-235157, It is described in Japanese Patent Application No. 7-235158. These organic bases can be used alone or in combination of two or more. The amount of the organic base used in the present invention is not particularly limited, but it is preferably used in the range of 1 to 30 mol with respect to 1 mol of the diazo compound.

  When preparing a coating solution for a heat-sensitive recording material in the present invention, it is more preferable to use a water-coating type than a solvent-coated type in which a coupler is dissolved in an organic solvent. This is preferable from the viewpoint of workability and recording characteristics of the heat-sensitive recording material. As a water coating type, the coupler of the present invention is added to a water-soluble polymer together with other components and dispersed in a solid using a sand mill or the like, or is emulsified and dispersed in oil droplets using an appropriate emulsification aid. Examples of the method used as an emulsified liquid. It does not specifically limit regarding the solid dispersion method and the emulsification method, A conventionally well-known method can be used. Details of these methods are described in JP-A-59-190886, JP-A-2-141279, and JP-A-7-17145. Also, couplers with poor solubility in organic solvents are difficult to use after being emulsified and dispersed in oil droplets.

In order to avoid such a problem of solubility, the efficiency of emulsification and dispersion can be improved and stabilized by emulsifying and dispersing in the presence of the ionic liquid described above.
That is, the coupler liquid is preferably obtained by dissolving the coupler in an ionic liquid in the presence of an auxiliary solvent, if necessary, and emulsifying and dispersing the resulting liquid in an aqueous medium.
The amount of the ionic liquid used is preferably in the range of 0.05 to 5 g, particularly preferably in the range of 0.2 to 2 g, with respect to 1 g of the coupler. Along with the ionic liquid, a lipophilic solvent such as a carboxylic acid ester, a phosphoric acid ester, a hydrocarbon, a carboxylic acid amide, or an ether may be used.

The coupler liquid of the present invention will be described in more detail.
The coupler liquid of the present invention is obtained by dissolving a coupler in an ionic liquid. This coupler liquid is preferably obtained by emulsifying and dispersing a coupler in a ionic liquid in an aqueous medium. More preferably, the auxiliary solvent is removed after the emulsification dispersion.
When the coupler is dissolved in the presence of an ionic liquid (with an auxiliary solvent if necessary) and then emulsified and dispersed in an aqueous medium, a surfactant and / or a water-soluble polymer is used as a protective colloid. It is preferable to mix and disperse by mixing with the aqueous phase. From the viewpoint of facilitating emulsification and dispersion, it is particularly preferable to use a surfactant.
In the present invention, as described above, an auxiliary solvent, preferably a low-boiling-point dissolution aid can be added as necessary. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.
The water-soluble polymer to be incorporated as a protective colloid in the aqueous phase mixed with the oil phase containing these components can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers. However, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable.
As the surfactant to be contained in the aqueous phase, an anionic or nonionic surfactant that does not act on the protective colloid to cause precipitation or aggregation can be appropriately selected and used. Preferable surfactants include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sulfosuccinate sodium salt, polyalkylene glycol (for example, polyoxyethylene nonyl phenyl ether) and the like.
The emulsified dispersion in the present invention can be easily obtained by mixing and dispersing the oil phase and the aqueous phase containing the above-mentioned components using means such as high-speed stirring and ultrasonic dispersion, which are used for usual fine particle emulsification. it can.

  When emulsifying and dispersing the quaternary salt compound coupler represented by the general formula (1), the emulsification and dispersion efficiency can be further improved by emulsifying and dispersing in the presence of a compound having active hydrogen. It becomes an aspect.

  Examples of such organic compounds having active hydrogen or acidic protons include phenol derivatives, naphthol derivatives, alkoxy-substituted benzenes, alkoxy-substituted naphthalenes, hydroxy compounds, carboxylic acid amide compounds, carboxylic acids, sulfonamide compounds, and sulfonic acids. Can be mentioned. The reason why the emulsification dispersibility is improved by adding a compound having active hydrogen is not necessarily clear, but it is assumed that salt exchange with a quaternary salt coupler is performed. In addition, the compound having active hydrogen also has an action of promoting a color development reaction (function as a color development aid). This may lower the melting point of a coupler or a basic substance, or may be microscopic. It is considered that the heat permeability of the capsule wall is improved, and as a result, a high color density can be obtained.

The organic compound having active hydrogen is preferably a compound having a hydroxyl group, an amino group, a carboxyl group, or a sulfo group (SO ₃ H group), a compound having an aminosulfonyl group, or a compound having a carbamoyl group. A hydroxyl group, a carboxyl group, a sulfo group (SO ₃ H group) and an aminosulfonyl group are preferred. The active hydrogen compound is added in an amount of 0.1 to 5 mol%, preferably 0.3 to 3 mol%, based on the coupler. When the addition amount is less than 0.1 mol%, the above-mentioned effects cannot be obtained. When the addition amount is more than 5 mol%, the weight of the coating solution increases, so the above range is preferable. As specific examples, the following are preferable.

The method for producing a heat-sensitive recording material of the present invention comprises preparing a coating solution containing a diazo compound, the above coupler solution, and other additives, and coating a bar, blade coating on a support such as paper or a synthetic resin film, It is carried out 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 to provide a heat-sensitive recording layer having a solid content of ^{2 to} 30 g / m ² .

  The binder used in the present invention is not particularly limited, and conventionally known binders such as polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, styrene-acrylic acid copolymer and the like can be used. Details are described in JP-A-2-141279 and the like. In addition, various organic or inorganic pigments, various stabilizers, antioxidants and the like can be added as necessary.

  In the heat-sensitive recording material of the present invention, a diazo compound, a coupler and the like may be contained in the same layer, or a laminated type constitution in which they are contained in another layer can be taken.

  A conventionally well-known support body can be used as a support body used for this invention. Specifically, neutral paper, acid paper, recycled paper, polyolefin resin laminated paper, synthetic paper, polyester film, cellulose triacetate film such as cellulose triacetate film, polystyrene film, polyolefin film such as polypropylene film and polyethylene film, etc. These can be used alone or in combination. The thickness of the support is 20 to 200 μm. It is also possible to provide an intermediate layer between the support and the thermosensitive recording layer. This is described in JP-A 61-54980.

  In the heat-sensitive recording material of the present invention, it is preferable to provide a protective layer on the heat-sensitive recording layer, and it is more preferable to provide a protective layer. This protective layer is composed of a water-soluble polymer compound, a pigment and the like. From the viewpoint of achieving both light resistance and photofixability, the protective layer preferably contains a compound having an ultraviolet transmittance adjusting function. A thermosensitive recording material containing a compound having an ultraviolet transmittance adjusting function is described in detail in JP-A-7-276808.

  The heat-sensitive recording material of the present invention can be used for multicolor heat-sensitive recording materials. Regarding this multicolor thermal recording material (thermal recording material), JP-A-4-135787, JP-A-4-144784, JP-A-4-144785, JP-A-4-194842, JP-A-4-247447. No. 4-247448, No. 4-340540, No. 4-340541, No. 5-34860, and the like. Specifically, it can be obtained by laminating heat-sensitive recording layers that develop colors having different hues. The layer structure is not particularly limited, but as an example, a thermal recording layer 2 in which two diazo compounds having different photosensitive wavelengths are combined with a coupler that reacts with each diazo compound when heated to produce different hues. Examples thereof include a multicolor thermosensitive recording material in which a layer (B layer, C layer) and a thermosensitive recording layer (A layer) in which an electron donating colorless dye and an electron accepting compound are combined are laminated. Specifically, a first thermosensitive recording layer (A layer) containing an electron-donating colorless dye and an electron-accepting compound on a support, a diazo compound having a maximum absorption wavelength of 360 nm ± 20 nm, and a reaction with the diazo compound when heated A second thermosensitive recording layer (B layer) containing a coupler that develops color, a diazo compound having a maximum absorption wavelength of 400 ± 20 nm, and a third coupler containing a coupler that reacts with the diazo compound when heated to develop a color. The heat-sensitive recording layer (C layer) is used. In this example, if the color hues of the respective heat-sensitive recording layers are selected to be the three primary colors in the subtractive color mixing, yellow, magenta, and cyan, full-color image recording becomes possible.

  In the recording method of this multicolor thermosensitive recording material, first, the third thermosensitive recording layer (C layer) is heated, and the diazonium salt compound and coupler contained in the layer are colored. Next, after irradiating light of 400 ± 20 nm to decompose and photofix the unreacted diazo compound contained in the C layer, heat sufficient to cause the second thermosensitive recording layer (B layer) to develop color. To color the diazo compound and the coupler contained in the layer. At this time, the C layer is also strongly heated at the same time, but the diazo compound has already been decomposed (photofixed), and the color developing ability is lost, so no color is developed. Further, irradiation with 360 ± 20 nm light is performed to decompose the diazo compound contained in the B layer, and finally, the first heat-sensitive recording layer (A layer) is given sufficient heat to cause color development. At this time, the heat-sensitive recording layers C and B are also strongly heated at the same time. However, since the diazo compound is already decomposed and the coloring ability is lost, no color is developed.

  Also, couplers that color all the heat-sensitive recording layers (in order from the top layer, layer A, layer B and layer C) by reacting three kinds of diazo compounds with different photosensitive wavelengths with the respective diazo compounds when heated. It can also be composed of a heat-sensitive recording layer in combination. In particular, such a layer configuration is required when aiming at improving the image quality by reducing the influence on the image quality due to the roughness on the surface of the support by making the yellow layer with low visibility as the lowest layer. . When all the heat-sensitive recording layers (A layer, B layer, C layer) are diazo heat-sensitive recording layers, the A layer and the B layer need to be subjected to photofixing after color development. For the C layer, it is not necessary to perform photofixing.

  Various fluorescent lamps, xenon lamps, mercury lamps, and the like are used as the fixing light source used for the above-described light fixing. It is preferable that this emission spectrum substantially coincides with the absorption spectrum of the diazo compound used in the heat-sensitive recording material, since it can be efficiently photofixed.

  When recording on the heat-sensitive recording material of the present invention, the material is exposed through an original, the diazo compound other than the image forming portion is decomposed to form a latent image, and then the entire material is heated and thermally developed to obtain an image. It can also be used as a heat-developable photosensitive material.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the examples, “parts” are all parts by weight.
[Example 1]
[Preparation of microcapsule solution A]
To 19 parts of ethyl acetate, 2.8 parts of a diazonium salt compound (Exemplary Compound (8) -2, maximum absorption wavelength: 370 nm) and 10 parts of tricresyl phosphate were added and mixed uniformly. Next, 7.6 parts of Takenate D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.) was added to this mixed solution as a wall agent and mixed uniformly to obtain a liquid I. Next, 46 parts of an 8% by weight aqueous solution of phthalated gelatin, 17.5 parts of water and 2 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate were added to this solution I, and 40 ° C., 10000 r.p. p. m. For 10 minutes. After adding 20 parts of water to the obtained emulsion and homogenizing it, a microcapsule solution A was obtained by carrying out a microencapsulation reaction at 40 ° C. for 3 hours while stirring. The average particle size of the microcapsules was 0.7 to 0.8 μm.

[Preparation of coupler emulsion B]
A liquid II obtained by dissolving 3.0 parts of a coupler (Exemplary Compound (C-8)), 3.0 parts of triphenylguanidine, and 0.74 part of an ionic liquid (Exemplary Compound I-6) in 10.5 parts of ethyl acetate. Obtained. Next, 49 parts of a 15% by weight aqueous solution of lime-processed gelatin, 9.5 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, and 35 parts of water were uniformly mixed at 40 ° C., and the II solution was added to the mixture using a homogenizer. 10000r. p. m. For 10 minutes. The obtained emulsion was stirred at 40 ° C. for 2 hours to remove ethyl acetate, and then the weight of volatilized ethyl acetate and water was supplemented by addition of water to obtain a coupler emulsion B.

[Preparation of thermal recording layer coating solution C]
3.6 parts of microcapsule liquid A, 3.3 parts of water, and 9.5 parts of coupler emulsion B were uniformly mixed to obtain a thermal recording layer coating liquid C.

[Preparation of protective layer coating solution D]
100 parts of a 6% aqueous solution of itaconic acid-modified polyvinyl alcohol (KL-318; trade name, manufactured by Kuraray Co., Ltd.) and 10 parts of a dispersion of 30% epoxy-modified polyamide (FL-71; trade name, manufactured by Toho Chemical Co., Ltd.) Into the mixed liquid, 15 parts of a dispersion of zinc stearate 40% (Hydrin Z; trade name, manufactured by Chukyo Yushi Co., Ltd.) was uniformly mixed to obtain a protective layer coating liquid D.

[Application]
On the photographic paper support laminated with polyethylene on fine paper, the thermal recording layer coating solution C and the protective layer coating solution D are sequentially applied and dried at 50 ° C. with a wire bar to obtain the desired thermal recording material. Obtained. The coating amount as a solid content was 8.0 g / m ² and 1.2 g / m ² , respectively.

[Color development test]
Using a thermal head (KST type) manufactured by Kyocera Corporation, the applied power and pulse width to the thermal head are determined so that the recording energy per unit area is 50 mJ / mm ^2, and after thermal printing, the emission center wavelength is 365 nm or 420 nm. The whole surface was irradiated with light using an ultraviolet lamp with an output of 40 W for 15 seconds. The density of the image part and the background part of the obtained sample was measured with a Macbeth densitometer.

(Image light resistance test)
The image area developed using a thermal head (KST type) manufactured by Kyocera Corporation was irradiated with light for 24 hours continuously at 30000 lux using a fluorescent light resistance tester, and the density of the image area was measured. The higher the density of the image area after light irradiation, the better the image light resistance.

[Image Fixability Test]
In the image fixing property test, a thermal head (KST type) manufactured by Kyocera Corporation is used for the background portion (unprinted portion) of the fixed sample, and the thermal head is set so that the recording energy per unit area is 40 mJ / mm ^2. The applied power and pulse width were determined for the thermal printing, and the concentration change was examined. The lower the density after printing, the better the image fixing property.

[Example 2]
A thermosensitive recording material was prepared and evaluated in the same manner as in Example 1 except that an emulsion was obtained using the coupler (C-23) instead of the coupler (C-8) used in Example 1.

[Example 3]
A thermosensitive recording material was prepared and evaluated in the same manner as in Example 1 except that an emulsion was obtained using the coupler (C-54) instead of the coupler (C-8) used in Example 1.

[Example 4]
A thermosensitive recording material was prepared and evaluated in the same manner as in Example 1 except that an emulsion was obtained using the coupler (C-55) instead of the coupler (C-8) used in Example 1.

[Example 5]
A thermosensitive recording material was prepared in the same manner as in Example 1, except that an ionic liquid (I-26) was used instead of the ionic liquid (Exemplary Compound I-6) used in Example 3, and an emulsion was obtained. Prepared and evaluated.

[Example 6]
A thermosensitive recording material was prepared in the same manner as in Example 1 except that the ionic liquid (I-51) was used instead of the ionic liquid (Exemplary Compound I-6) used in Example 3 to obtain an emulsion. Prepared and evaluated.

[Example 7]
In Example 3, a thermosensitive recording material was prepared and evaluated in the same manner except that 1.0 part of a color former (active hydrogen compound) (4) was further added during the preparation of the coupler emulsion.

[Comparative Examples 1-4]
A thermosensitive recording material was prepared in the same manner as in Example 1 except that an emulsion was obtained using tricresyl phosphate instead of the ionic liquid (Exemplary Compound I-6) used in Examples 1 to 4. Tried to evaluate ,.
However, in Comparative Examples 1 to 3, the coupler was not dissolved when the coupler emulsion B was prepared, and an emulsified dispersion could not be obtained. Since Comparative Example 4 was able to obtain an emulsified dispersion, a thermosensitive recording material was prepared and evaluated in the same manner as in Example 1.
Table 1 shows the evaluation of the above examples and comparative examples.

  According to the method of the present invention, the coupler can be stably dissolved and emulsified and dispersed. By using the emulsified dispersion thus obtained, a high color density can be obtained, and image light resistance and image fixability are also good. A diazo thermosensitive recording material can be provided. Furthermore, when the coupler represented by the general formula (1) is used, a heat-sensitive recording material having a good hue can be obtained.

Claims (7)

  A method for producing a recording material comprising coating a support containing a diazonium salt compound-containing liquid and a coupler liquid containing a coupler that reacts with the diazonium salt compound to form a color, wherein the coupler liquid is converted into an ionic liquid. A method for producing a recording material obtained by dissolving.   2. The method for producing a recording material according to claim 1, wherein the coupler liquid is obtained by emulsifying and dispersing a liquid obtained by dissolving the coupler in the presence of an ionic liquid in an aqueous medium.   The ionic liquid is one or more selected from imidazolium salts, pyrazolium salts, pyridinium salts, pyrimidinium salts, pyrazinium salts, thiazolium salts, oxazolium salts, tetraalkylammonium salts and tetraalkylphosphonium salts. 2. A method for producing a recording material according to 2.   4. The method for producing a recording material according to claim 1, wherein the coupler is a cationic compound. 5. The recording material according to claim 4, wherein the cationic compound is a compound represented by the following general formula (1).

[Wherein, X and Y may be the same or different and each represents an atom selected from the group consisting of C, N, O, P and S, and X and Y are bonded via a linking group. R represents an alkyl, aryl or aralkyl group which may have a substituent. X, Y, and the linking group for linking X and Y may have a substituent, and the heterocyclic ring represented by the above formula may be further condensed with a ring. A ⁻ represents a counter anion. ]   In a recording material having a microcapsule encapsulating a diazonium salt compound on the support and a coupler that develops color by reacting with the diazonium salt compound outside the microcapsule, the coupler is dissolved in an ionic liquid. A recording material characterized by:   7. The ionic liquid is one or more selected from imidazolium salts, pyrazolium salts, pyridinium salts, pyrimidinium salts, pyrazinium salts, thiazolium salts, oxazolium salts, tetraalkylammonium salts and tetraalkylphosphonium salts. Recording material.