JP2003321451A - Diazonium salt and thermal recording material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new diazonium salt having maximum absorption (λmax) at ≥400 nm and a thermal recording material having excellent optical fixing properties with a light source of ≥400 nm wavelength and preservability and shows little texture coloring properties. <P>SOLUTION: The diazonium salt is represented by general formula (1) (wherein R<SP>1</SP>-R<SP>4</SP>are each H, a halogen, an alkyl, an alkoxy, an alkylthio, an arylthio, an alkylsulfonyl, an arylsulfonyl; R<SP>5</SP>-R<SP>10</SP>are each H, an alkyl, an aryl, an acyl and an alkoxy-carbonyl; R<SP>11</SP>-R<SP>14</SP>are H, a halogen an alkyl, an alkoxy, an alkylthio, an arylthio, an alkylsulfonyl, an arylsulfonyl, sulfamoyl, an alkoxycarbonyl, carbamoyl and cyano; X<SP>-</SP>is an anion). The thermal recording material is produced by using the diazonium salt. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diazonium salt excellent in photofixability with a light source having a wavelength longer than 400 nm and a heat-sensitive recording material using the diazonium salt and a coupler as a color-forming component, and more particularly to a thermosensitive recording material having a wavelength longer than 400 nm. The present invention relates to a heat-sensitive recording material which is excellent in light fixing property with a light source, is excellent in preservability, and has little background coloring.

[0002]

Diazonium salts are known as important synthetic intermediates for azo dyes. Various methods have been conventionally known for synthesizing azo dyes, and "New Experimental Chemistry Course" (Maruzen Co., Ltd., Volume 14-III, 1516-15).
As described on page 34), there are various synthetic methods such as synthesis by oxidation reaction, synthesis by reduction reaction, synthesis by substitution reaction, synthesis by addition reaction, and synthesis by condensation reaction. However, it is widely used as an industrial production method of an azo dye, from the viewpoint of availability of raw materials, cost, yield, etc., it is synthesized by azo coupling a diazonium salt with a coupler such as aniline or phenol. Is the way to do it. In such a method, there is a risk that the diazonium salt will explode in the course of synthesis, and there has been a demand for the development of a stable diazonium salt that is less likely to cause the explosion.

On the other hand, diazonium salts are disclosed in JP-A-11-2.
As described in No. 28517, it is used for quantitative analysis of bilirubin, which is the main component of bile pigment contained in body fluids, and is positioned as an important compound in the fields of medicine and pharmaceuticals.

The diazonium salt is generally a compound having a very high chemical activity, and easily reacts with a compound having a phenol derivative or an active methylene group, so-called a coupler, to form an azo dye, and also has photosensitivity. It has the property of decomposing upon irradiation with light and losing its activity. Therefore, the diazonium salt has been used for a long time as an optical recording material typified by diazo copy (Corporation (1982) p. 89, edited by The Photographic Society of Japan, "Basics of Photographic Engineering-Non-silver Salt Photographed Edition"). ~ P117,
p. 182-P201).

Further, recently, it has been applied to a recording material that requires fixing of an image by utilizing the property of decomposing by light and losing its activity. As a typical one, a recording containing a diazonium salt and a coupler is used. A light-fixing type heat-sensitive recording material has been proposed in which a recording material having a layer is heated and reacted according to an image signal to form an image, and then the image is irradiated with light to fix the image (Koji Sato et al., IEICE). Magazine Volume 11 Fourth
Issue (1982) p. 290-296 etc.).

In these recording materials using a diazonium salt as a color-forming component, the chemical activity of the diazonium salt is very high, and the diazonium salt gradually decomposes in the dark to lose its reactivity. There is a drawback that the shelf life as a recording material is short. Further, in the background portion which is the non-image portion, the residual diazonium salt compound is decomposed during the photo-fixing, and the non-image portion is colored due to the generation of the colored decomposition product (stain). further,
Even in the completed image after fixing, the non-image area has weak light resistance,
There is also a drawback that coloring is increased when left for a long time under sunlight or fluorescent light.

Various methods have been proposed so far as means for improving such instability of the diazonium salt. One of the most effective means is to enclose the diazonium salt in microcapsules. By encapsulating the diazonium salt in microcapsules, the diazonium salt is isolated from the substances that promote decomposition, such as water and bases, so that the decomposition is significantly suppressed, and the shelf life of recording materials using this is dramatically improved. (Tomomasa Usami et al., “Electrophotographic Society Journal”, Vol. 26, No. 2 (1987), p. 115-125).

As described above, as a general method for encapsulating the diazonium salt in the microcapsules, the diazonium salt is dissolved in a hydrophobic solvent (oil phase), and this is dissolved in an aqueous solution in which a water-soluble polymer is dissolved (water. Phase) in addition to emulsifying and dispersing with a homogenizer, etc., and adding a monomer or prepolymer that becomes the wall material of the microcapsules to either the oil phase side or the water phase side, or both, Causes a polymerization reaction at the interface between the
Alternatively, it is a method of forming microcapsules by depositing a polymer to form a wall made of a polymer compound. Such a method is described in detail in, for example, "Microcapsule" (written by Asashi Kondo, published by Nikkan Kogyo Shimbun, 1970), "Microcapsule" (written by Tamotsu Kondo et al., Sankyo Publishing, 1977). Has been done.

As the capsule wall of the formed microcapsules, various materials such as crosslinked gelatin, alginates, celluloses, urea resins, urethane resins, melamine resins and nylon resins are used. In particular, in the case of microcapsules having a glass transition temperature such as urea resin and urethane resin, and the glass transition temperature thereof has a wall slightly higher than room temperature, at room temperature, the capsule wall exhibits substance impermeability, Since it exhibits substance permeability above the glass transition temperature, it is called a thermoresponsive microcapsule and can be said to be very useful for a heat-sensitive recording material.

That is, in a thermosensitive recording material in which a thermosensitive microcapsule containing a diazonium salt and a thermosensitive recording layer containing a coupler as a color-forming main component are provided on the support, the diazonium salt is long. At the same time as it can be kept stable for a period of time, it is possible to easily form a color image by heating, and it is also possible to fix the formed image by further irradiating with light. Therefore, by encapsulating the diazonium salt in microcapsules, it became possible to dramatically improve the stability as a recording material.

As described above, although the stability as a heat-sensitive recording material is remarkably improved, the instability caused by the diazonium salt itself is not completely suppressed, and the heat-sensitive recording material is sufficiently stable. It has not reached the desired long-term storage stability. In addition, even after printing and fixing, the photodecomposition product of the diazonium salt causes a photodecomposition reaction when exposed to a light source for a long time, and the coloring stain increases with the reaction, resulting in non-image formation after photofixation. There is also a problem in that the whiteness of a portion (background portion) is lowered, and the contrast with the colored portion is also lowered. Also,
It is known that the photodegradation reaction as described above cannot occur uniformly and that various decomposition products are produced depending on the surrounding environment and the like, and photodegradation stains are contained in several tens or more of the products. Yields a product which has absorption especially in the visible region. Here, if the occurrence of this stain is significant, the whiteness of the non-image area (background area) after light fixation is lowered, and the contrast with the color development area is also reduced, resulting in a marked loss of the commercial value of the recording material itself. Become.

However, since the photolysis reaction of the diazonium salt is complicated and the product thereof is difficult to specify, it is difficult to suppress the photolysis stain. Therefore, in recent years, much research has been conducted on the improvement of long-term stabilization due to photolytic stain. For example, in JP-A No. 8-324129, a hydrophobic property specific to microcapsules containing a photo-fixing diazonium salt is specified. A light-fixing heat-sensitive recording material has been proposed which, when used in combination with a functional oil, has excellent raw storability and at the same time has excellent image storability that does not impair whiteness even when exposed to light for a long time after image formation. There is. Further, JP-A No. 11-78232 proposes a non-fixing type heat-sensitive recording material using a novel diazonium salt for the purpose of improving the stability of the diazonium salt itself.
That is, a microcapsule contains a diazonium salt having a maximum light absorption wavelength in a shorter wavelength region than around 350 nm,
The non-fixing type heat-sensitive recording material using the microcapsules can improve the whiteness of the background and the image storability after image formation under a light source typified by a fluorescent lamp having a wavelength longer than around 350 nm. Proposed.

However, depending on the preservation environment, the raw preservation ability,
At present, the image storability in the color-developed part and the background part (non-image part) after image recording is not sufficient, and further improvement in stability is demanded. Further, in recent years, there has been a great demand for shortening the recording time required for image recording, that is, speeding up of image formation including printing and fixing. Particularly, in the light fixing type heat-sensitive recording material using a diazonium salt, as described above. There is a strong demand for a technique capable of achieving high speed while improving various stability, and in order to meet the demand, it is an essential condition to improve the photolysis rate of the diazonium salt itself.

These recording materials using a diazonium salt as a color-forming component are generally irradiated with ultraviolet rays having a wavelength of about 360 nm in the fixing step in order to efficiently perform optical fixing. However, since ultraviolet rays require a special light source and there is a problem that they may affect the eyes, a recording material using a diazonium salt that can be efficiently fixed to a visible light source having a wavelength longer than 400 nm. Was required.

However, the conventional recording material using a diazonium salt has a problem that fixing is slow and takes a long time when deactivating with a light source having a wavelength longer than 400 nm. Further, there is a problem in that, if light fixing is performed for a long time for the purpose of completely fixing, the product generated by fixing further reacts, and a color image with low background whiteness may be formed.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the various problems in the prior art and achieve the following objects. The present invention has a maximum absorption wavelength (λmax) of 40.
(EN) It is intended to provide a novel diazonium salt having a wavelength of more than 0 nm, and a heat-sensitive recording material using the diazonium salt, which is excellent in photofixability with a light source having a wavelength longer than 400 nm, is excellent in preservability, and has less background coloring.

[0017]

The objects of the present invention can be achieved by the following means. The present invention is, therefore, <1> a diazonium salt represented by the following general formula (1).

[Chemical 4]

[In the general formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, It represents an arylsulfonyl group, and R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an aryl group, an acyl group or an alkoxycarbonyl group. In addition, R ⁵ and R ⁷ ,
R ⁵ and R ⁸ , R ⁶ and R ⁷ , R ⁶ and R ⁸ , R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸ and R ^9, and R ⁸ and R ¹⁰ are bonded to each other to form a ring. You may. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom, an alkyl group,
It represents an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group, and a cyano group. X ⁻ represents an anion. ]

<2> The diazonium salt is the diazonium salt according to <1>, which is represented by the following general formula (2).

[Chemical 5]

[In the general formula (2), R ¹ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group or an arylsulfonyl group, and R ⁵ , R ⁶ and R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group or an aryl group. R ⁵ and R ⁷ , R ⁵ and R ⁸ , R ⁶ and R ⁷ ,
R ⁶ and R ⁸ , R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸ and R ⁹ and R ⁸ and R ¹⁰ may be bonded to each other to form a ring. R ¹¹ ,
R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom,
It represents a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group, and a cyano group. X ⁻ represents an anion. ]

<3> A thermosensitive recording material having a thermosensitive recording layer containing a diazonium salt and a coupler on the surface of a support, wherein the diazonium salt is the diazonium salt described in <1>. It is a thermosensitive recording material.

<4> The thermosensitive recording material according to <3>, wherein the diazonium salt is the diazonium salt according to <2>.

<5> The thermosensitive recording material according to <3> or <4>, wherein the coupler is a compound represented by the following general formula (3) or a tautomer thereof.

[Chemical 6]

[In the general formula (3), E ¹ and E ² each independently represent an electron-withdrawing group. Also, E ¹ and E ²
May combine with each other to form a ring. ]

<6> The diazonium salt is encapsulated in microcapsules <3> to <5>.
The heat-sensitive recording material as described in any one of 1.

<7> The heat-sensitive recording material according to <6>, wherein the capsule wall of the microcapsule contains polyurethane and / or polyurea.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The diazonium salt of the present invention and the heat-sensitive recording material using the same are described in detail below.

<Diazonium Salt> The diazonium salt of the present invention is characterized by being represented by the following general formula (1).

[Chemical 7]

In the above general formula (1), R ¹ , R ² , R
³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group or an arylsulfonyl group.

The halogen atom represented by R ¹ , R ² , R ³ and R ⁴ is preferably a chlorine atom or a bromine atom.

The alkyl group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the alkyl group is 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 preferable. As the alkyl group represented by R ¹ , R ² , R ³ and R ⁴ , specifically, an alkyl group having a total carbon number of 1 to 30 (including the carbon number of the introduced substituent) is preferable, and for example, , Methyl group, ethyl group, butyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2-hydroxyethyl group, 2-benzoyloxyethyl group, 2- (4 Preferable examples are -butoxyphenoxy) ethyl group and benzyl group. Among these, total carbon number 1
The alkyl group of -18 is more preferable, and methyl group, ethyl group, butyl group, 2-ethylhexyl group, dodecyl group and octadecyl group are particularly preferable.

The alkoxy group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and a substituent which can be introduced into the alkoxy group is 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 preferable. Specific examples of the alkoxy group represented by R ¹ , R ² , R ³ and R ^{4 above} include:
Total carbon number (including carbon number of introduced substituent) 1 to 30
Is preferred, and examples thereof include a methoxy group, a butoxy group, a 3-pentyloxy group, a 2-ethylhexyloxy group, an octyloxy group, a 3,5,5-trimethylhexyloxy group, a dodecyloxy group, an octadecyloxy group, 2 -Ethoxyethoxy group, 2-chloroethoxy group, 2-phenoxyethoxy group, and benzyloxy group are preferred. Among these, an alkoxy group having a total carbon number of 1 to 18 is more preferable, and a methoxy group, a butoxy group, 3
-Pentyloxy group, 2-ethylhexyloxy group,
The 3,5,5-trimethylhexyloxy group is particularly preferred.

The alkylthio group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and a substituent which can be introduced into the alkylthio group is a phenyl group, Halogen atom, alkoxy group, 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. The above R ¹ , R ² and R ³
And the alkylthio group represented by R ⁴ includes, specifically, a total carbon number of 1 to 1 (including the carbon number of the introduced substituent).
The alkylthio group of 30 is preferable, and preferable examples thereof include a methylthio group, an ethylthio group, a butylthio group, a cyclohexylthio group, an octylthio group, a 2-ethylhexylthio group, a dodecylthio group, a 2-hydroxyethylthio group and a benzylthio group. Among these, total carbon number 1 to 1
The alkylthio group of 8 is more preferable, and a methylthio group, a cyclohexylthio group, an octylthio group and a dodecylthio group are particularly preferable.

The arylthio group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and a substituent which can be introduced into the arylthio group is a phenyl group, Halogen atom, alkoxy group, 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. The above R ¹ , R ² and R ³
And the arylthio group represented by R ⁴ specifically includes a total carbon number of 6 to 6 (including the carbon number of the introduced substituent).
The arylthio group of 30 is preferable, and examples thereof include a phenylthio group, a 2-butoxycarbonylphenylthio group, a 2-chlorophenylthio group, a 4-chlorophenylthio group, and a 4-chlorophenylthio group.
A methylphenylthio group is preferred. Among these, an arylthio group having 6 to 18 carbon atoms is more preferable, and a phenylthio group, 4-chlorophenylthio group, 4-
A methylphenylthio group is particularly preferred.

The alkylsulfonyl group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the alkylsulfonyl group is phenyl. A 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 preferable. As the alkylsulfonyl group represented by R ¹ , R ² , R ³ and R ⁴ , specifically, an alkylsulfonyl group having 1 to 30 total carbon atoms (including the carbon number of the introduced substituent) is preferable. Preferred examples include methylsulfonyl group, butylsulfonyl group, octylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, and benzylsulfonyl group. Among these, an alkylsulfonyl group having 1 to 18 carbon atoms is more preferable, and a methylsulfonyl group, an octylsulfonyl group, a dodecylsulfonyl group,
The benzylsulfonyl group is particularly preferred.

The arylsulfonyl group represented by R ¹ , R ² , R ³ and R ⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the arylsulfonyl group is phenyl. A 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 preferable. As the arylsulfonyl group represented by R ¹ , R ² , R ³ and R ⁴ , specifically, an arylsulfonyl group having 6 to 30 carbon atoms (including the carbon number of the introduced substituent) is preferable. Suitable examples include a phenylsulfonyl group, a 2-chlorophenylmethylsulfonyl group, a 2-chlorophenylsulfonyl group, a 4-chlorophenylsulfonyl group, and a 4-chlorophenylmethylsulfonyl group. Among these, an arylsulfonyl group having 6 to 18 carbon atoms is more preferable, and a phenylsulfonyl group and a 4-chlorophenylsulfonyl group are particularly preferable.

In the above general formula (1), R ⁵ , R ⁶ and R
⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an aryl group, an acyl group or an alkoxycarbonyl group. R ⁵ and R ⁷ , R ⁵ and R ⁸ , R ⁶ and R ⁷ , R ⁶ and R ⁸ , R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸ and R ⁹ and R ⁸ and R ¹⁰ are , May combine with each other to form a ring.

The aforementioned R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰
The alkyl group represented by may be unsubstituted or may have a substituent, and 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 and an acyloxy group. Group, acylamino group, carbamoyl group, cyano group, carboxylic acid group,
A sulfonic acid group and a heterocyclic group are preferable. The above R ⁵ , R ⁶ ,
Specific examples of the alkyl group represented by R ⁷ , R ⁸ , R ⁹ and R ¹⁰ include (the carbon number of the introduced substituent).
An alkyl group having a total carbon number of 6 to 30 is preferable, and examples thereof include a methyl group, an ethyl group, a butyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, an octadecyl group, and 2-hydroxyethyl. Base,
A 2-benzoyloxyethyl group, a 2- (4-butoxyphenoxy) ethyl group and a benzyl group are preferred.
Among these, an alkyl group having a total carbon number of 1 to 18 is more preferable, and a methyl group, an ethyl group, a butyl group, an octyl group and a dodecyl group are particularly preferable.

The above R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰
The aryl group represented by may be unsubstituted or may have a substituent, and 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 and an acyloxy group. Group, acylamino group, carbamoyl group, cyano group, carboxylic acid group,
A sulfonic acid group and a heterocyclic group are preferable. The above R ⁵ , R ⁶ ,
Specific examples of the aryl group represented by R ⁷ , R ⁸ , R ⁹ and R ¹⁰ include (the carbon number of the introduced substituent).
An aryl group having a total of 6 to 30 carbon atoms is preferable, and for example, a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and a 4-butoxyphenyl group are suitable. Among these, an aryl group having 6 to 18 carbon atoms is more preferable, and a phenyl group and a 4-methylphenyl group are particularly preferable.

The aforementioned R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰
The acyl group represented by may be unsubstituted or may have a substituent, and as the substituent which can be introduced into the acyl group, 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 preferable. The above R ⁵ , R ⁶ ,
As the acyl group represented by R ⁷ , R ⁸ , R ⁹ and R ¹⁰ ,
Specifically, an acyl group having a total carbon number of 6 to 30 (including the carbon number of the introduced substituent) is preferable, and examples thereof include an acetyl group, a butanoyl group, an octanoyl group, and a benzoyl group. Among these, an acyl group having a total carbon number of 1 to 8 is more preferable, and an acetyl group, a butanoyl group and a benzoyl group are particularly preferable.

The above R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰
The alkoxycarbonyl group represented by may be unsubstituted or may have a substituent, and as the substituent which can be introduced into the alkoxycarbonyl group, 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 preferable. The aforementioned R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R
^{As the} alkoxycarbonyl group represented by ¹⁰ , specifically, the total carbon number (including the carbon number of the introduced substituent) is 2 to
The alkoxycarbonyl group of 30 is preferable, and for example, a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, an octyloxycarbonyl group, a dodecyloxycarbonyl group, a 2-phenoxyethoxycarbonyl group, and a benzyloxycarbonyl group are preferable. Among these, an alkoxycarbonyl group having 2 to 18 carbon atoms is more preferable, and a methoxycarbonyl group, an ethoxycarbonyl group, and an octyloxycarbonyl group are particularly preferable.

In the above general formula (1), R ¹¹ , R ¹² ,
R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group,
It represents an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group, or a cyano group.

The halogen atom represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ is preferably a chlorine atom or a bromine atom.

The alkyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the alkyl group is 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 preferable. The above R ¹¹ , R ¹² , R ¹³
And as the alkyl group represented by R ¹⁴ , specifically,
Total carbon number (including carbon number of introduced substituent) 1 to 30
Is preferably an alkyl group, for example, a methyl group, an ethyl group, a butyl group, a hexyl group, a heptyl group, an octyl group,
Preferable examples include 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, 2-hydroxyethyl group, 2-benzoyloxyethyl group, 2- (4-butoxyphenoxy) ethyl group, and benzyl group. Among these, an alkyl group having 1 to 18 carbon atoms is more preferable, a methyl group,
Particularly preferred are ethyl group, butyl group, octyl group, 2-ethylhexyl group, dodecyl group and octadecyl group.

The alkoxy group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may 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 preferable. The above R ¹¹ , R ¹² , R
^{As the} alkoxy group represented by ¹³ and R ¹⁴ , specifically, the total number of carbon atoms (including the carbon number of the introduced substituent) is 1 to 1
30 alkoxy groups are preferable, for example, a methoxy group,
Butoxy group, 3-pentyloxy group, 2-ethylhexyloxy group, octyloxy group, 3,5,5-trimethylhexyloxy group, dodecyloxy group, octadecyloxy group, 2-ethoxyethoxy group, 2-chloroethoxy group, A 2-phenoxyethoxy group and a benzyloxy group are preferred. Among these, an alkoxy group having a total carbon number of 1 to 18 is more preferable, a methoxy group, a butoxy group,
Octyloxy group and 3,5,5-trimethylhexyloxy group are particularly preferable.

The alkylthio group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and a substituent which can be introduced into the alkylthio group is 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 preferable. Said R ¹¹ ,
Specific examples of the alkylthio group represented by R ¹² , R ¹³ and R ¹⁴ include (the carbon number of the introduced substituent).
An alkylthio group having 1 to 30 carbon atoms is preferable, and for example, a methylthio group, an ethylthio group, a butylthio group, a cyclohexylthio group, an octylthio group, a 2-ethylhexylthio group, a dodecylthio group, a 2-hydroxyethylthio group, and a benzylthio group are preferable. Are listed in. Among these,
An alkylthio group having 1 to 18 carbon atoms is more preferable, a methylthio group, a cyclohexylthio group, an octylthio group,
The dodecylthio group is particularly preferred.

The arylthio group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and a substituent which can be introduced into the arylthio group is 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 preferable. Said R ¹¹ ,
Specific examples of the arylthio group represented by R ¹² , R ¹³ and R ¹⁴ include (the carbon number of the introduced substituent).
An arylthio group having a total of 6 to 30 carbon atoms is preferable, and preferable examples thereof include a phenylthio group, a 2-butoxycarbonylphenylthio group, a 2-chlorophenylthio group, a 4-chlorophenylthio group, and a 4-methylphenylthio group. Among these, an arylthio group having 6 to 18 carbon atoms is more preferable, and a phenylthio group, a 4-chlorophenylthio group, and a 4-methylphenylthio group are particularly preferable.

The alkylsulfonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the alkylsulfonyl group is phenyl. A 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 preferable. As the alkylsulfonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ , specifically, an alkylsulfonyl group having 1 to 30 total carbon atoms (including the carbon number of the introduced substituent) is preferable. Preferred examples include methylsulfonyl group, butylsulfonyl group, octylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, and benzylsulfonyl group. Among these, total carbon number 1
The alkylsulfonyl group of 18 is more preferable, and a methylsulfonyl group, an octylsulfonyl group, a dodecylsulfonyl group, and a benzylsulfonyl group are particularly preferable.

The arylsulfonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the arylsulfonyl group is phenyl. A 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 preferable. As the arylsulfonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ , specifically, an arylsulfonyl group having 6 to 30 carbon atoms (including the carbon number of the introduced substituent) is preferable. Suitable examples include a phenylsulfonyl group, a 2-chlorophenylmethylsulfonyl group, a 2-chlorophenylsulfonyl group, a 4-chlorophenylsulfonyl group, and a 4-chlorophenylmethylsulfonyl group.
Among these, an arylsulfonyl group having 6 to 18 carbon atoms is more preferable, and a phenylsulfonyl group and a 4-chlorophenylsulfonyl group are particularly preferable.

The sulfamoyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent that can be introduced into the sulfamoyl group is
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 preferable. Said R ¹¹ ,
Specific examples of the sulfamoyl group represented by R ¹² , R ¹³ and R ¹⁴ include (the carbon number of the introduced substituent is included)
An arylsulfonyl group having a total of 6 to 30 carbon atoms is preferable,
For example, N, N-dimethylsulfamoyl group, N, N-
Diethylsulfamoyl group, N, N-dipropylsulfamoyl group, N, N-dibutylsulfamoyl group, N,
N-dioctylsulfamoyl group, N, N-bis (2-
Ethylhexyl) sulfamoyl group, N-ethyl-N-
Benzylsulfamoyl group, N-ethyl-N-butylsulfamoyl group, N-ethyl-N-phenylsulfamoyl group, pyrrolidinosulfonyl group, morpholinosulfonyl group, 4-octanoylpiperazinosulfonyl group are preferred. Are listed in. Among these, a sulfamoyl group having a total carbon number of 1 to 18 is more preferable, and an N, N-dimethylsulfamoyl group, N, N-dipropylsulfamoyl group, N,
Particularly preferred are N-dibutylsulfamoyl group, N, N-dioctylsulfamoyl group and pyrrolidinosulfonyl group.

The alkoxycarbonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the alkoxycarbonyl group is phenyl. A 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 preferable. As the alkoxycarbonyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ , specifically, an alkoxycarbonyl group having 2 to 30 total carbon atoms (including the carbon number of the introduced substituent) is preferable. Preferred examples include a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, an octyloxycarbonyl group, a dodecyloxycarbonyl group, a 2-phenoxyethoxycarbonyl group, and a benzyloxycarbonyl group. Among these, an alkoxycarbonyl group having 2 to 18 carbon atoms is more preferable, and a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, and an octyloxycarbonyl group are particularly preferable.

The carbamoyl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be unsubstituted or may have a substituent, and the substituent which can be introduced into the carbamoyl group is 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 preferable. Said R ¹¹ ,
Specific examples of the carbamoyl group represented by R ¹² , R ¹³ and R ¹⁴ include (including the carbon number of the introduced substituent).
A carbamoyl group having 2 to 30 carbon atoms is preferable, and examples thereof include N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N, N-dipropylcarbamoyl group, N, N-dibutylcarbamoyl group and N, N. -Dioctylcarbamoyl group, N, N-bis (2-ethylhexyl) carbamoyl group, N-ethyl-N-benzylcarbamoyl group, N-ethyl-N-butylcarbamoyl group, N
Preferable examples include -ethyl-N-phenylcarbamoyl group, piperidinocarbonyl group, pyrrolidinocarbonyl group, morpholinocarbonyl group, and 4-octanoylpiperazinocarbonyl group. Among these, a carbamoyl group having a total of 2 to 18 carbon atoms is more preferable, and an N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N, N-
A dibutylcarbamoyl group, an N, N-dioctylcarbamoyl group and a pyrrolidinocarbonyl group are particularly preferable.

In the above general formula (1), X ⁻ represents an anion. The anion represented by X ⁻ may be either an inorganic anion or an organic anion. As the inorganic anion, for example, hexafluorophosphate ion, borofluoride ion, chloride ion, and sulfate ion are preferable, and hexafluorophosphate ion and borofluoride ion are particularly preferable. As the organic anion, for example, polyfluoroalkylcarboxylate ion,
Preferable examples include polyfluoroalkyl sulfonate ion, tetraphenyl borate ion, aromatic carboxylate ion, and aromatic sulfonate ion. Among them, polyfluoroalkyl sulfonate ion, tetraphenyl borate ion, aromatic carboxylate ion Is particularly preferable.

Among the diazonium salts represented by the above general formula (1), the diazonium salts represented by the following general formula (2) are more preferable.

[Chemical 8]

In the general formula (2), R ¹ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group or an arylsulfonyl group. A halogen atom represented by R ¹ , an alkyl group, an alkoxy group, an alkylthio group,
The arylthio group, the alkylsulfonyl group and the arylsulfonyl group are represented by R ¹ , R ² and R ³ in the above general formula (1).
And a halogen atom represented by R ⁴ , an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, and an arylsulfonyl group, and the preferred examples are also the same.

In the general formula (2), R ⁵ , R ⁶ , R ⁷ ,
R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group or an aryl group. R ⁵ and R ⁷ , R ⁵ and R ⁸ , R ⁶ and R ⁷ , R ⁶ and R ⁸ , R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸
And R ⁹ and R ⁸ and R ¹⁰ may combine with each other to form a ring. The alkyl group and aryl group represented by R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same as R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ^{9 in the} above general formula (1). And has the same meanings as the alkyl group and aryl group represented by R ¹⁰ , and preferred examples are also the same.

In the general formula (2), R ¹¹ , R ¹² , and R ¹³
And R ¹⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group or a cyano group. X ⁻ represents an anion. A halogen atom, an alkyl group, an alkoxy group, an alkylthio group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ ;
The arylthio group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, alkoxycarbonyl group, carbamoyl group and cyano group are halogen atoms represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the above general formula (1), Alkyl group, alkoxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, alkoxycarbonyl group,
It has the same meaning as a carbamoyl group and a cyano group, and preferred examples are also the same. However, at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ is any one of an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group and a cyano group. Represents

In the general formula (2), X ⁻ represents an anion, and the anion has the same meaning as the anion represented by X ⁻ in the general formula (1), and the preferred examples are also the same.

Further, the diazonium salts represented by the general formulas (1) and (2) include R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
^{R 6, R 7, R 9} , R 10, R 11, R 12, R 13 and R ¹⁴ has a diazo niobium phenyl group as a substituent, it may form a bis-or higher multimers.

The general formula (1) or (2) of the present invention will be described below.
Illustrative compounds (A-1) to (A-20) are shown as specific examples of the diazonium salt represented by, but the present invention is not limited thereto.

[0061]

[Chemical 9]

[0062]

[Chemical 10]

The diazonium salt represented by the general formula (1) or (2) can be produced by a known method. That is, it can be obtained by diazotizing the corresponding aniline with sodium nitrite, nitrosylsulfuric acid, isoamyl nitrite or the like in an acidic solvent.

The diazonium salt represented by the general formula (1) or (2) may be either an oily substance or a crystalline state, but it is preferably a crystalline state at room temperature from the viewpoint of handleability. These diazonium salts of the present invention may be used alone or in combination of two or more, or may be used in combination with existing diazonium salts. When the diazonium salt of the present invention is used in the heat-sensitive recording layer of a heat-sensitive recording material,
The content thereof is preferably from 0.02 to 5 g / m ^2, more preferably 0.1-4 g / m ² from the viewpoint of color density.

In order to stabilize the diazonium salt of the present invention, it is also possible to stabilize the diazonium salt by forming a complex compound using zinc chloride, cadmium chloride, tin chloride or the like.

The diazonium salt represented by the above general formula (1) or (2) develops a color by a reaction with a coupler described later, and a high color density can be obtained.
It has excellent photodegradability in the wavelength range of 460 nm, and has high-speed decomposability capable of completing fixing even with irradiation of light for a short time, and thus is very useful as a color-forming component used in a photofixing type heat-sensitive recording material. .

<Coupler> Next, a coupler (coupling component) usable in the heat-sensitive recording material of the present invention will be described. The coupler has a basic atmosphere and /
Alternatively, any compound can be used as long as it is capable of forming a dye by coupling with a diazonium salt in a neutral atmosphere. All so-called 4-equivalent couplers for silver halide photographic light-sensitive materials can be used as couplers. These can be selected according to the desired 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. Specific examples thereof include the following, which are used within the scope of the object of the present invention.

Specific examples of the coupler include, for example,
Resorcin, phloroglucin, 2,3-dihydroxynaphthalene, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, sodium 2-hydroxy-3-naphthalenesulfonate, 2-hydroxy -3-Naphthalenesulfonic acid anilide, 2-hydroxy-3-naphthalenesulfonic acid morpholinopropylamide, 2-hydroxy-3-naphthalenesulfonic acid-2-ethylhexyloxypropylamide, 2-hydroxy-3-naphthalenesulfonic acid-2- Ethylhexylamide, 5-acetamido-1-naphthol, 1-hydroxy-8-acetamidonaphthalene-3,6-disulfonate sodium, 1-hydroxy-8-acetamidonaphthalene-
3,6-disulfonic acid dianilide, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid anilide, 5, 5-dimethyl-1,3-cyclohexanedione, 1,3-cyclopentanedione, 5- (2-n-tetradecyloxyphenyl) -1,3-cyclohexanedione, 5-phenyl-4-methoxycarbonyl-1 ，
3-cyclohexanedione, 5- (2,5-di-n-octyloxyphenyl) -1,3-cyclohexanedione,

N, N'-dicyclohexylbarbituric acid, N, N'-di-n-dodecylbarbituric acid, N-
n-octyl-N'-n-otatadecyl barbituric acid, N-phenyl-N '-(2,5-di-n-octyl oxydiphenyl) barbituric acid, N, N'-bis (octadecyloxycarbonyl) Methyl) barbituric acid,
1-phenyl-3-methyl-5-pyrazolone, 1-
(2,4,6-Trichlorophenyl) -3-anilino-
5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-benzamido-5-pyrazolone, 6-hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) -2-pyridone, 2 , 4-bis- (benzoylacetamido) toluene, 1,3-bis- (pivaloylacetamidomethyl) benzene, benzoylacetonitrile, thenoylacetonitrile, acetoacetanilide,
Benzoyl acetanilide, pivaloyl acetanilide, 2-chloro-5- (N-n-butylsulfamoyl) -1-bivaloyl acetamidebenzene, 1- (2
-Ethylhexyloxypropyl) -3-cyano-4-
Methyl-6-hydroxy-1,2-dihydropyridine-
2-one, 1- (dodecyloxypropyl) -3-acetyl-4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (4-n-octyloxyphenyl) -3-tert- Butyl-5-aminopyrazole and the like can be mentioned.

Details of the coupler are described in JP-A-4-4-2.
01483, JP-A-7-223367, JP-A-7-
No. 223368, JP-A-7-323660, and Japanese Patent Application No. 5
-278608, Japanese Patent Application No. 5-297024, Japanese Patent Application No. 6-18669, Japanese Patent Application No. 6-18670, Japanese Patent Application No. 7
-316280, Japanese Patent Application No. 0-027095, Japanese Patent Application No. 8-027096, Japanese Patent Application No. 08-030799, Japanese Patent Application No. 8-12610, Japanese Patent Application No. 8-132394, Japanese Patent Application No. 8-358755. Japanese Patent Application No. 8-358756, Japanese Patent Application No. 9-069990 and the like.

Of the above, in the present invention, the compound represented by the following general formula (3) or a tautomer thereof is particularly preferable. The coupler represented by formula (3) is described in detail below.

[Chemical 11]

In the general formula (3), E ¹ and E ² are
Each independently represents an electron-withdrawing group. Further, E ¹ and E ² may combine with each other to form a ring.

The electron-withdrawing group represented by E ¹ and E ² means a substituent having a positive Hammett's σ _p value, which may be the same or different. Acetyl group, propionyl group, pivaloyl group, chloroacetyl group, trichloroacetyl group, trifluoroacetyl group, 1-methylcyclopropylcarbonyl group, 1
-Acyl groups such as ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group and thenoyl group; methoxycarbonyl group, ethoxycarbonyl group, 2-methoxyethoxycarbonyl group, 4-methoxyphenoxy group Oxycarbonyl group such as carbonyl group; carbamoyl group, N, N-
Dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N-phenylcarbamoyl group, N- [2,4-bis (pentyloxy) phenyl] carbamoyl group, N-
[2,4-bis (octyloxy) phenyl] carbamoyl group, carbamoyl group such as morpholinocarbonyl group;
Alkylsulfonyl group or arylsulfonyl group such as methanesulfonyl group, benzenesulfonyl group, toluenesulfonyl group; phosphono group such as diethylphosphono group; benzoxazol-2-yl group, benzothiazole-2
-Yl group, 3,4-dihydroquinazolin-4-one-2
A heterocyclic group such as an -yl group or a 3,4-dihydroquinazoline-4-sulfon-2-yl group; a heterocyclic group; a nitro group; an imino group; a cyano group are preferable.

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

Illustrative compounds (B-1) to (B-38) are shown below as specific examples of the coupler represented by formula (3), but the present invention is not limited thereto.
Incidentally, the tautomers of the couplers shown below can also be mentioned as preferable ones.

[0076]

[Chemical 12]

[0077]

[Chemical 13]

[0078]

[Chemical 14]

[0079]

[Chemical 15]

[0080]

[Chemical 16]

[0081]

[Chemical 17]

The tautomer of the coupler is a compound which exists as an isomer of the coupler represented by the above and has a structure in which the structures thereof easily change. The tautomer is also preferable as the coupler used in.

<Microencapsulation> In the heat-sensitive recording material of the present invention, it is preferable to enclose the diazonium salt in microcapsules for the purpose of improving the raw storability before use. The method for forming the microcapsules can be appropriately selected from known methods.

The polymer substance forming the capsule wall of the microcapsule must be impermeable at room temperature and permeable when heated.
Particularly, those having a glass transition temperature of 60 to 200 ° C. are preferable, and examples thereof include polyurethane, polyurea, polyamide,
Examples thereof include polyester, urea / formaldehyde resin, melamine resin, polystyrene, styrene / methacrylate copolymer, styrene / acrylate copolymer, and mixed systems thereof.

As a method for forming microcapsules, specifically, an interfacial polymerization method or an internal polymerization method is suitable. For details of the capsule forming method, specific examples of the reactant, etc., see US Pat. Nos. 3,726,804 and 3,311.
It is described in the specification such as 766,669. For example, when polyurea or polyurethane is used as the capsule wall material, polyisocyanate and a second substance (for example, polyol or polyamine) that reacts with it to form a capsule wall are mixed in an aqueous medium or an oily medium to be encapsulated. Then, these are emulsified and dispersed in water and then heated to cause a polymer forming reaction at the oil droplet interface to form a microcapsule wall. Note that polyurea can be produced even when the addition of the second substance is omitted.

In the present invention, the polymer substance forming the capsule wall of the microcapsule preferably contains at least one of polyurethane and polyurea as a component.

Next, a method for producing the diazonium salt-containing microcapsules (polyurea / polyurethane wall) will be described. First, the diazonium salt is dissolved or dispersed in a hydrophobic organic solvent that serves as the core of the capsule to prepare an oil phase that serves as the core of the microcapsule. At this time, polyvalent isocyanate is further added as a wall material.

In the preparation of the oil phase, the hydrophobic organic solvent used for forming the core of the microcapsule by dissolving and dispersing the diazonium salt is preferably an organic solvent having a boiling point of 100 to 300 ° C., for example, alkylnaphthalene, Alkyldiphenylethane, alkyldiphenylmethane, alkylbiphenyl, alkylterphenyl, chlorinated paraffin, phosphoric acid esters, maleic acid esters, adipic acid esters, phthalic acid esters, benzoic acid esters, carbonic acid esters, ethers, Examples thereof include sulfuric acid esters and sulfonic acid esters. These are 2
You may use it in mixture of 2 or more types.

When the diazonium salt to be encapsulated has a poor solubility in the above-mentioned organic solvent, a low-boiling solvent having a high solubility for the diazonium salt to be used may be supplementarily used. Examples thereof include ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methylene chloride, tetrahydrofuran, acetonitrile, acetone and the like.

Therefore, the diazonium salt preferably has an appropriate solubility in a high-boiling point hydrophobic organic solvent or a low-boiling point solvent. Specifically, it has a solubility of 5% or more in the solvent. Is preferred. The solubility in water is preferably 1% or less.

On the other hand, an aqueous solution in which a water-soluble polymer is dissolved is used as the aqueous phase to be used, and the oil phase is added thereto, followed by emulsification and dispersion by means of a homogenizer or the like. And acts as a dispersion medium to stabilize the emulsion-dispersed aqueous solution. Here, a surfactant may be added to at least one of the oil phase and the water phase in order to further uniformly emulsify and stabilize the emulsion. As the surfactant, a known surfactant for emulsification can be used. When the surfactant is added, the addition amount is preferably 0.1 to 5% by mass with respect to the mass of the oil phase,
0.5-2 mass% is more preferable.

The water-soluble polymer used in the prepared water-soluble polymer aqueous solution in which the oil phase is dispersed is preferably a water-soluble polymer having a water solubility of 5% or more at the temperature at which it is intended to emulsify. 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, polyvinylpyrrolidone , Ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch derivative, arabic gum, sodium alginate and the like.

The water-soluble polymer preferably has no or low reactivity with an isocyanate compound,
For example, gelatin having a reactive amino group in its molecular chain, such as gelatin, is preferably preliminarily modified to eliminate the reactivity.

As the polyvalent isocyanate compound,
A compound having a trifunctional or higher functional isocyanate group is preferable, but a bifunctional isocyanate compound may be used.
Specifically, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product, and diisocyanate such as isophorone diisocyanate are used as main raw materials, and their dimers or trimers (buret or isocyanate) are used. Nurate), a polyfunctional adduct of a polyol such as trimethylolpropane and a bifunctional isocyanate such as xylylenediisocyanate, or an adduct of a polyol such as trimethylolpropane and a bifunctional isocyanate such as xylylenediisocyanate. Examples thereof include compounds in which a high molecular weight compound such as polyether having active hydrogen such as polyethylene oxide is introduced, and formalin condensates of benzene isocyanate.

The compounds described in JP-A-62-212190, JP-A-4-26189, JP-A-5-317694, and Japanese Patent Application No. 8-268721 are preferable.

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 an emulsion dispersion obtained by adding an oil phase to an aqueous phase,
At the interface between the oil phase and the water phase, a polyurea polymerization reaction occurs to form a polyurea wall.

If a polyol and / or polyamine is further added to the hydrophobic solvent in the aqueous phase or the oil phase, it can be used as one of the constituent components of the microcapsule wall by reacting with the polyvalent isocyanate. . In the above reaction, it is preferable to keep the reaction temperature high or to add an appropriate polymerization catalyst from the viewpoint of accelerating the reaction rate.

Specific examples of these polyols or polyamines include propylene glycol, glycerin, trimethylolpropane, triethanolamine, sorbitol and hexamethylenediamine. A polyurethane wall is formed when the polyol is added.

Polyisocyanates, polyols, reaction catalysts, polyamines for forming a part of wall materials, etc. are well known in the book (edited by Keiji Iwata, Polyurethane Handbook, Nikkan Kogyo Shimbun (1987)).

The emulsification can be carried out by appropriately selecting from known emulsification devices such as a homogenizer, a Manton Gorey, an ultrasonic disperser, a dissolver, and a Keddy mill.
After the emulsification, the emulsion is heated to 30 to 70 ° C. to accelerate the capsule wall forming reaction. Further, during the reaction, in order to prevent aggregation of the capsules, it is necessary to add water to reduce the collision probability of the capsules and to perform sufficient stirring.

A dispersion for preventing aggregation may be added again during the reaction. Generation of carbon dioxide gas is observed with the progress of the polymerization reaction, and its termination can be regarded as the approximate end point of the capsule wall forming reaction. Usually, the desired diazonium salt-containing microcapsules can be obtained by reacting for several hours.

Next, the coupler used in the present invention can be used by solid-dispersing it with a sand mill or the like together with, for example, a water-soluble polymer, an organic base, and other color-forming aids, but it is particularly preferable to use water beforehand. Emulsified by dissolving in a sparingly soluble or insoluble high boiling point organic solvent, then mixing this with an aqueous polymer solution (aqueous phase) containing a surfactant and / or a water-soluble polymer as a protective colloid, and emulsifying with a homogenizer etc. It is preferably used as a dispersion. In this case, a low boiling point solvent may be used as a dissolution aid, if necessary. Further, the coupler and the organic base can be separately emulsified and dispersed, or can be mixed and then dissolved in a high-boiling point organic solvent to be emulsified and dispersed. A preferable emulsified dispersed particle diameter is 1 μm or less. The amount of the coupler used is 0.1 to 30 parts with respect to 1 part by mass of the diazonium salt.
Parts by mass are preferred.

The high boiling organic solvent used in this case is
For example, it can be appropriately selected from the high boiling point oils described in JP-A-2-141279. Among them, esters are preferable, and tricresyl phosphate is particularly preferable, from the viewpoint of emulsion stability of the emulsified dispersion. The above oils can be used together or with other oils.

In the organic solvent, as a dissolution aid,
A low-boiling auxiliary solvent may be added, and suitable examples of the auxiliary solvent include ethyl acetate, isopropyl acetate, butyl acetate, and methylene chloride. Depending on the case, it is also possible to use only the low-boiling auxiliary solvent without containing the high-boiling oil.

As the water-soluble polymer to be contained as a protective colloid in the aqueous phase, known anionic polymers,
It can be appropriately selected from nonionic polymers and amphoteric polymers, and among them, for example, 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 which does not cause precipitation or aggregation by acting on the protective colloid is used. can do. Examples of the surfactant include sodium alkylbenzenesulfonate, sodium alkylsulfate, sodium dioctyl sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether), and the like.

In the present invention, it is also a preferred embodiment to add an organic base as a basic substance for the purpose of promoting the coupling reaction between the diazonium salt and the coupler.
Examples of the organic base include nitrogen-containing compounds such as tertiary amines, piperidines, piperazines, amidines, formamidines, pyridines, guanidines, morpholines, and the like. -46806, JP62-70082, JP57-16
9745, JP 60-94381 A, JP 57-123086 A, JP 60-49991 A.
Japanese Patent Publication, Japanese Patent Publication No. 2-24916, Japanese Patent Publication No. 2-28
Preferable examples are those described in JP-A No. 479, JP-A-60-165288, and JP-A-57-185430. These may be used alone or in combination of two or more.

Of the above, specifically, 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-
Piperazines such as bis {[3- (N-methylpiperazino) -2-hydroxy] propyloxy) benzene, N-
[3- (β-naphthoxy) -2-hydroxy] propylmorpholine, 1,4-bis (3-morpholino-2-hydroxy-propyloxy) benzene, 1,8-bis (3
-Morpholino-2-hydroxy-propyloxy) benzene and other morpholines, N- (3-phenoxy-2-hydroxypropyl) piperidine, N-dodecylpiperidine and other piperidines, triphenylguanidine, tricyclohexylguanidine, dicyclohexylphenylguanidine Guanidines and the like are preferable.

The amount of the organic base used is preferably 0.1 to 30 parts by mass with respect to 1 part by mass of the diazonium salt. If the amount used is less than 0.1 parts by mass, sufficient color density may not be obtained, and if it exceeds 30 parts by mass, decomposition of the diazonium salt may be accelerated.

In addition to the above organic bases, a color-forming aid may be added to the heat-sensitive recording layer for the purpose of accelerating the color-forming reaction, that is, for rapid and complete thermal printing with low energy. Here, the color-forming aid is a substance that increases the color-developing density during heating recording or controls the color-forming temperature, and lowers the melting point of the coupler, the basic substance or the diazonium salt, or the softening point of the capsule wall. It is for the purpose of making the conditions in which the diazonium salt, the basic substance, the coupler and the like are easily reacted by the action capable of decreasing

Examples of the color forming aid include phenol derivatives, naphthol derivatives, alkoxy-substituted benzenes, alkoxy-substituted naphthalenes, aromatic ethers, thioethers, esters, amides, ureides, urethanes,
Examples thereof include sulfonamide compounds and hydroxy compounds.

The color-forming aid also includes a heat-meltable substance. The heat-fusible substance is a substance that is solid at room temperature and has a melting point of 50 ° C. to 150 ° C. that melts when heated, and is a substance that can dissolve a diazonium salt, a coupler, an organic base, or the like. Specifically, carboxylic acid amide, N
Examples thereof include substituted carboxylic acid amides, ketone compounds, urea compounds, and esters.

In the heat-sensitive recording material of the present invention, the fastness of a color-developed image to light and heat is improved, or
For the purpose of reducing yellowing of the unprinted part (non-image part) after fixing due to light, it is also preferable to use the following known antioxidants and the like.

Regarding the antioxidant, for example, European Patent Publication Nos. 223739 and 30940.
No. 1, JP 309402, and JP 310551.
No. 3,310,552, No. 459,416, German Published Patent No. 3,435,443, Japanese Unexamined Patent Publication No. 54-48535, No. 62-262047, No. 63-113536, No. 63-163335.
No. 1, JP-A-2-262654, JP-A-2-
71262, JP-A-3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275 and the like. It is also effective to use various known additives already used in heat-sensitive or pressure-sensitive recording materials.

Examples of the various additives include, for example, JP-A-60-107384, JP-A-60-107383, JP-A-60-125470, and JP-A-60-12547.
No. 1, gazette 60-125472, gazette 60-28.
7485, 60-287486, 60
-287487, 60-287488,
61-160287, 61-185483, 61-211079, and 62-1466.
No. 78, No. 62-146680, No. 62-1
46679, 62-282885, and 6
No. 3-051174, No. 63-89877,
63-88380, 63-088831, 63-203372, 63-22498.
9 publication, 63-251282 publication, 63-26.
No. 7594, No. 63-182484, Japanese Unexamined Patent Publication No. 1-239282, No. 4-291685,
4-291684, 5-188868, 5-188686, 5-110490, 5-170361, and JP-B-48-043.
The compounds described in JP-A No. 294, 48-033212 and the like can be mentioned.

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 cyclohexanoate, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2- Ethylhexane, 2
-Methyl-4-methoxy-diphenylamine, 1-methyl-2-phenylindole and the like can be mentioned.

The amount of the antioxidant or various additives added is 0.0 with respect to 1 part by mass of the diazonium salt.
5 to 100 parts by mass is preferable, and 0.2 to 30 parts by mass is more preferable. The antioxidant and various additives may be contained together with the diazonium salt in the microcapsules, or may be contained as a solid dispersion together with the coupler, the basic substance and other color-forming aids, and emulsification. It may be contained as a product together with a suitable emulsification aid, or may be contained in both forms. Also,
The antioxidant or various additives may be used alone or in combination of two or more. Further, it can be contained in the protective layer.

The antioxidant and various additives do not necessarily have to be added to the same layer. When a plurality of combinations of the above-mentioned antioxidants and / or various additives are used, they are structurally classified as anilines, alkoxybenzenes, binder phenols, hindered amines, hydroquinone derivatives, phosphorus compounds and sulfur compounds. Then
Those having different structures may be combined, or a plurality of the same may be combined.

A free radical generator (a compound capable of generating a free radical upon irradiation with light) used in a photopolymerizable composition or the like can be added for the purpose of reducing yellow coloring of the background portion after image recording. Examples of the free radical generator include aromatic ketones, quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, acyloxime esters and the like. The amount of the free radical generator added is 0.01 to 1 part by mass of the diazonium salt.
5 parts by mass is preferred.

Similarly, for the purpose of reducing yellow coloring, a polymerizable compound having an ethylenically unsaturated bond (hereinafter,
It is called a "vinyl monomer". ) Can also be used. A 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 a monomer or a prepolymer.

Examples of the vinyl monomer include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids with aliphatic polyhydric alcohols, and amides of unsaturated carboxylic acids with aliphatic polyhydric amine compounds. To be The vinyl monomer is used in an amount of 1 part by mass of the diazonium salt.
It is used in a proportion of 0.2 to 20 parts by mass. The free radical generator and the vinyl monomer may be used by being contained in a microcapsule together with a diazonium salt. Furthermore, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid or the like can be added as an acid stabilizer.

<Heat-sensitive recording material> The heat-sensitive recording material of the present invention comprises at least a heat-sensitive recording layer on a support, and the heat-sensitive recording layer has at least one of the general formulas (1) and (2). It comprises the diazonium salt represented and a coupler, and optionally an organic base and other additives. A plurality of diazonium salts represented by the general formula (1) or (2) can be used in combination.

The thermosensitive recording layer contains microcapsules containing a diazonium salt represented by the general formula (1) or (2), a coupler, and if necessary, an organic base and other additives. It can be applied by preparing a coating solution, applying the coating solution on a support such as paper or synthetic resin film, and drying.

In the present invention, the heat-sensitive recording layer is organic.
The embodiment containing a base is preferred. The coating is a known coating.
It can be appropriately selected from the cloth methods, for example, bar
Coating, blade coating, air knife coating, gravure coating,
Roll coating, spray coating, dip coating
Examples include cloth and curtain coating. Also, after coating and drying
The dry coating amount of the heat-sensitive recording layer is 2.5 to 30 g /
m ²Is preferred.

The constitution of the heat-sensitive recording layer in the heat-sensitive recording material of the present invention is not particularly limited, and for example, it is composed of a single layer in which microcapsules, couplers, organic bases and the like are all contained in the same layer. It may be an aspect, or may be an aspect of a multi-layer laminated type that is included in another layer. In addition, Japanese Patent Application No. 59-177669 on the support.
Alternatively, the intermediate layer described in the specification or the like may be provided, and then the heat-sensitive recording layer may be formed by coating.

Further, as will be described later, a full color coloring type mode in which a plurality of monochromatic and single thermosensitive recording layers having different hues are laminated may be used.

In the heat-sensitive recording material of the present invention, each layer such as the heat-sensitive recording layer, the intermediate layer or the protective layer described below may contain a binder, and the binder may be a known water-soluble polymer compound or latex. It can be appropriately selected from the above.

Examples of the water-soluble polymer compound include methyl cellulose, carboxymethyl cellulose,
Hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivative, casein, gum arabic, gelatin, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, polyvinyl alcohol, silanol modified polyvinyl alcohol, carboxy modified polyvinyl alcohol, epichlorohydrin modified Polyamide, isobutylene-maleic salicylic anhydride copolymer,
Examples thereof include polyacrylic acid, polyacrylic acid amide, and modified products thereof.

Examples of the latexes include styrene-butadiene rubber latex and methyl acrylate.
Examples thereof include butadiene rubber latex and vinyl acetate emulsion. Among them, hydroxyethyl cellulose,
Starch derivatives, gelatin, polyvinyl alcohol derivatives, polyacrylic acid amide derivatives and the like are preferable.

Further, the heat-sensitive recording material of the present invention may contain a pigment, and known pigments may be organic or inorganic, and examples thereof include kaolin, calcined kaolin, talc and wax. , Diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone ko, silica, magnesium carbonate, titanium oxide, alumina, barium carbonate, barium sulfate, mica, Microballoons, urea-formalin fillers, polyester particles, cellulose fillers and the like can be mentioned.

If desired, various known additives such as waxes, antistatic agents, defoaming agents, conductive agents, fluorescent dyes, surfactants, ultraviolet absorbers and precursors thereof may be used. .

In the heat-sensitive recording material of the present invention, a protective layer may be provided on the heat-sensitive recording layer, if necessary. The protective layer may be laminated in two or more layers if necessary. As the material used for the protective layer, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins,
Gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sulfone Water-soluble polymer compounds such as acid soda and sodium alginate, and styrene-
Examples thereof include latexes such as butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion.

By cross-linking the water-soluble polymer compound, the storage stability can be further improved.
The cross-linking agent can be appropriately selected from known cross-linking agents, and examples thereof include water-soluble initial condensates such as N-methylol urea, N-methylol melamine, and urea-formalin; dioxal such as glyoxal and glutaraldehyde. Aldehyde compounds; inorganic crosslinking agents such as boric acid and borax; polyamide epichlorohydrin and the like.

Known pigments, metal soaps, waxes, surfactants and the like can be used in the protective layer. The coating amount of the protective layer is 0.2 to 5 as a dry coating amount.
preferably ^{g / m 2, 0.5~2g / m} 2 is more preferable. The film thickness is preferably 0.2 to 5 μm,
0.5-2 micrometers is more preferable.

When the protective layer is provided, a known ultraviolet absorber or its precursor may be contained in the protective layer. The protective layer can be provided by the above-mentioned known coating method as in the case of forming the heat-sensitive recording layer on the support.

As the support that can be used in the heat-sensitive recording material of the present invention, any paper support used in ordinary pressure-sensitive paper or heat-sensitive paper, dry or wet diazo copying paper, etc. can be used. Acidic paper, neutral paper, coated paper, plastic film laminated paper, synthetic paper, and plastic films such as polyethylene terephthalate and polyethylene naphthalate can be used.

A back coat layer may be provided on the support for the purpose of correcting the curl balance or improving the chemical resistance from the back surface. The back coat layer can be provided in the same manner as the protective layer.

If necessary, an antihalation layer may be provided between the support and the heat-sensitive recording layer or on the surface of the support on the side where the heat-sensitive recording layer is provided, and on the back surface thereof, a slip layer or an anti-slip layer. It is also possible to provide a static layer, a pressure-sensitive adhesive layer, or the like. Further, release paper may be combined with the back surface of the support (the surface on the side where the thermosensitive recording layer is not provided) via an adhesive layer to form a label.

As described above, by using the diazonium salt of the present invention in the thermosensitive recording layer, a high color density can be obtained and the optical fixing can be carried out at a high speed. This faster optical fixing speed realizes shorter recording time,
Further, since the diazonium salt itself has excellent decomposability, a sufficient fixing effect can be expected. Therefore, it is possible to prevent the whiteness from being deteriorated due to the coloring of the non-image portion (background portion), and it is possible to obtain a high-contrast image with little density fluctuation. That is, both improvement in stability as a recording material and speeding up can be realized. Furthermore, by encapsulating the diazonium salt in microcapsules, the long-term stability of the recording material can be further improved.

<Image Forming Method> Image formation using the thermosensitive recording material of the present invention may be carried out by the following method.
That is, for example, the surface of the heat-sensitive recording material on the side where the heat-sensitive recording layer is provided is imagewise printed by a heating device such as a thermal head, so that the polyurea and // Alternatively, when the capsule wall containing polyurethane is softened and becomes substance permeable, and a coupler or a basic substance (organic base) outside the capsule penetrates into the microcapsule, a color is imagewise formed to form an image. Good. In this case, after color development, by further irradiating with light corresponding to the absorption wavelength of the diazonium salt (photofixing), the diazonium salt undergoes a decomposition reaction and loses its reactivity with the coupler, and the image can be fixed. . When the photo-fixing is performed as described above, the unreacted diazonium salt undergoes a decomposition reaction and loses its activity. Therefore, the density of the formed image varies and the coloring occurs due to the generation of stains in the non-image area (background area). That is, it is possible to suppress a decrease in whiteness and a decrease in image contrast accompanying the decrease.

Examples of the light source used for the optical fixing include various fluorescent lamps, xenon lamps, mercury lamps, etc., and the emission spectrum of these light sources is almost the same as the absorption spectrum of the diazonium salt in the thermosensitive recording material. It is preferable in that it can be fixed with high efficiency. In particular, in the present invention,
It is particularly preferable to use a light source having an emission center wavelength of irradiating light of 380 to 460 nm.

Further, writing is performed in an imagewise manner by light,
It can also be used as an optical writing heat-developable heat-sensitive recording material which is subjected to heat development to form an image. In this case, the printing process
Instead of the heating device as described above, a light source such as a laser plays a role.

In the heat-sensitive recording material of the present invention, a multicolor heat-sensitive recording material can be constructed by laminating a plurality of heat-sensitive recording layers having different hues. Examples of the heat-sensitive recording layer to be laminated include a heat-sensitive recording layer containing a photodegradable diazonium salt. Regarding the multicolor thermosensitive recording material, JP-A-3-288688, 4-1.
No. 35787, No. 4-144784, No. 4-
No. 144785, No. 4-194842, No. 4
No. 247447, No. 4-247448, No. 4-340540, No. 4-340541,
No. 5-34860, No. 5-194842,
It is described in Japanese Patent Application No. 7-316280.

For example, the layer structure of the full-color thermosensitive recording material may be structured as follows.
However, the present invention is not limited to this. That is, two kinds of diazonium salts having different photosensitizing wavelengths,
Two thermosensitive recording layers having different coloring hues (B layer, combined with a coupler capable of reacting with each diazonium salt under heat to form different hues) in different layers.
C layer) and a thermosensitive recording layer (A layer) in which an electron-donating colorless dye and an electron-accepting compound are combined may be laminated to form a full-color thermosensitive recording material, or the thermosensitive recording layer of the above two layers. (B layer, C layer) and a thermosensitive recording layer (A layer) in which a diazonium salt having a different photosensitive wavelength from these and a coupler that reacts with the diazonium salt to develop a color when heated are combined.
It may be a full-color heat-sensitive recording material in which and are laminated.

Specifically, from the side of the support, an electron-donating colorless dye and an electron-accepting compound, or a diazonium salt having a maximum absorption wavelength shorter than 350 nm and a coupler which reacts with the diazonium salt to produce a color when heated are contained. The first heat-sensitive recording layer (A layer) having a maximum absorption wavelength of 360 nm ± 20 n
The second heat-sensitive recording layer (B) containing a diazonium salt of m and a coupler that develops a color when reacted with the diazonium salt
Layer), and a third thermosensitive recording layer (layer C) containing a diazonium salt having a maximum absorption wavelength of 400 ± 20 nm and a coupler that reacts with the diazonium salt to form a color when heated (layer C). Good.

In this case, full-color image recording can be performed by selecting the hues of the respective heat-sensitive recording layers to be the three primary colors in subtractive color mixing, yellow, magenta and cyan. As the layer structure of the full-color recording material, the yellow, magenta, and cyan color forming layers may be stacked in any manner, but from the viewpoint of color reproducibility, from the support side,
It is preferable to stack yellow, cyan, magenta, or yellow, magenta, and cyan in this order.

The recording method for a multicolor heat-sensitive recording material can be carried out, for example, as follows. That is, first, the third thermosensitive recording layer (C layer) is heated to develop the color of the diazonium salt and the coupler contained in the layer. Then, light of 400 ± 20 nm is irradiated to decompose the unreacted diazonium salt contained in the C layer. Next, sufficient heat is applied so that the second thermosensitive recording layer (B layer) develops color,
The diazonium salt and the coupler contained in the layer are colored. At this time, the C layer is also heated strongly at the same time, but since the diazonium salt has already been decomposed and the coloring ability has been lost, no coloring occurs. Then, the diazonium salt contained in the B layer is decomposed by irradiating with light of 360 ± 20 nm. Finally, sufficient heat is applied to the first heat-sensitive recording layer (A layer) to develop a color. At this time, the layers C and B are also strongly heated at the same time, but the diazonium salt has already been decomposed and the coloring ability has been lost, so that no coloring occurs.

The heat-sensitive recording material of the present invention is preferably a multicolor heat-sensitive recording material as described above. As described above, the thermal recording layer (A
The layer-forming mechanism is not limited to a combination of an electron-donating dye and an electron-accepting dye, or a combination of a diazonium salt and a coupler that reacts with the diazonium salt to generate a color when heated, and a basic compound It may be any of a base coloring system that develops a color upon contact with, a chelate coloring system, and a coloring system that reacts with a nucleophile to cause an elimination reaction to develop a color. A multicolor heat-sensitive recording material can be constructed by providing a heat-sensitive recording layer containing a diazonium salt and a coupler that reacts with the diazonium salt to develop a color on the heat-sensitive recording layer.
In the case of a multicolor thermosensitive recording material, an intermediate layer may be provided between the thermosensitive recording layers for the purpose of preventing color mixing between the thermosensitive recording layers.

The intermediate layer is made of a water-soluble polymer compound such as gelatin, phthalated gelatin, polyvinyl alcohol and polyvinylpyrrolidone, and may contain various additives as appropriate.

When the heat-sensitive recording material of the present invention is a multi-color heat-sensitive recording material having a light-fixing type heat-sensitive recording layer on a support, a light-transmittance adjusting layer or a protective layer may be further provided thereon as needed. It is desirable to provide a layer, or a light transmittance adjusting layer and a protective layer. The light transmittance adjusting layer is described in JP-A-9-39395, JP-A-9-39396, and Japanese Patent Application No. 7-208386.

When a component which functions as a precursor of an ultraviolet absorber is used in the light transmittance adjusting layer, it does not function as an ultraviolet absorber before it is irradiated with light in the wavelength region necessary for fixing, and thus it has a high light intensity. Due to its transmittance, when fixing the photo-fixing type thermosensitive recording layer, it is possible to sufficiently transmit the wavelength of the region necessary for fixing, and the high visible light transmittance also hinders the fixing of the thermosensitive recording layer. It won't come.

On the other hand, the precursor of the ultraviolet absorber is irradiated with light in a wavelength region necessary for photofixing of the photofixing type heat-sensitive recording layer (photolysis of diazonium salt by photoirradiation), and then reacted by the light. It comes to function as a raised UV absorber. This ultraviolet absorber absorbs most of the light having a wavelength in the ultraviolet region and reduces its transmittance, so that the light resistance of the heat-sensitive recording material can be improved. However, since it does not absorb visible light, the transmittance of visible light does not substantially change.

At least one light transmittance adjusting layer can be provided in the heat-sensitive recording material, and it is particularly preferable to form it between the heat-sensitive recording layer and the protective layer. Further, the protective layer may have the function of the light transmittance adjusting layer and may also be used.

[0155]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 Synthesis Example of Exemplified Compound A-1 Tetrahydroquinoline:
6.7 g and 2-n-octyloxy-4-fluoronitrobenzene: 13.5 g were added to DMAc (N, N-dimethylacetamide): 75 ml and cooled to 0 ° C. To this, potassium t-butoxide (5.6 g) was gradually added. The reaction solution was stirred at 0 ° C. for 2 hours, ethyl acetate and diluted hydrochloric acid were added to separate the layers. The ethyl acetate layer was concentrated, and the obtained crude crystals were purified by column chromatography to obtain compound 1-a represented by the following formula: 8.7 g.

[0157]

[Chemical 18]

The obtained compound 1-a was identified by ¹ H-NMR. The data are shown below. ¹ H-NMR (CDCl ₃ , 300 MHz) δ: 7.94
(D, 1H), 7.06-7.23 (m, 3H), 6.
95 (t, 1H), 6.75 (s, 1H), 6.71
(D, 1H), 3.98 (t, 2H), 3.68 (t,
2H), 2.78 (t, 2H), 2.04 (m, 2)
H), 1.81 (m, 2H), 1.47 (m, 2H),
1.22-1.39 (m, 8H), 0.88 (t, 3)
H)

Next, reduced iron: 5.6 g, ammonium chloride: 0.5 g, isopropanol: 40 ml and water:
The mixture was added to a mixed solvent with 10 ml and refluxed under heating, and 7.7 g of compound 1-a was dividedly added thereto as a solid. After heating under reflux for 30 minutes, the reaction solution was filtered through Celite. Ethyl acetate and water were added to the filtrate for liquid separation, and the ethyl acetate layer was concentrated to obtain compound 1-b represented by the following formula.

[0160]

[Chemical 19]

The compound 1-b was dissolved in 40 ml of methanol, 5.5 ml of concentrated hydrochloric acid was added, and the mixture was cooled to 0 ° C. Sodium nitrite: 1.5g and water: 4
A solution consisting of 10 ml of water was added dropwise, and the mixture was stirred at 10 ° C. for 1 hour, potassium hexafluorophosphate (4.8 g) was added to the reaction mixture, and the mixture was stirred at room temperature for 90 minutes. Crystallization was carried out by adding 10 ml of isopropanol and 100 ml of water. The precipitated crystals were collected by filtration, washed successively with water and isopropanol, and then recrystallized from a mixed solvent of ethyl acetate, isopropanol and hexane. After drying, 6.3 g of Exemplified compound A-1 represented by the following formula was obtained.

[0162]

[Chemical 20]

The diazonium salt A-1 thus obtained was converted into ¹ H--N
It was identified by MR. The data are shown below. ¹ H-NMR (acetone-d ₆ , 300 MHz)
δ: 7.91 (d, 1H), 7.20-7.36 (m,
4H), 6.92 (d, 1H), 6.61 (s, 1
H), 4.21 (t, 2H), 3.84 (t, 2H),
2.71 (t, 2H), 2.09 (m, 2H), 1.8
4 (m, 2H), 1.40 (m, 2H), 1.22-
1.39 (m, 8H), 0.85 (t, 3H) Further, the maximum absorption wavelength (λmax) in the ultraviolet-visible absorption spectrum in methanol is 401 nm, and the absorption coefficient ε is 3.0 × 10 ^4. It was

Example 2 (Synthesis Example of Exemplified Compound A-2) 6-n-octyloxy-tetrahydroquinoline: 9.0 g and 2- (3,5,5)
5-Trimethylhexyloxy) -4-fluoronitrobenzene: 9.8 g and DMAc (N, N-dimethylacetamide): 50 ml were added, and the mixture was cooled to 0 ° C.
To this, 3.9 g of potassium t-butoxide was gradually added. The reaction solution was stirred at 0 ° C. for 1.5 hours, ethyl acetate and diluted hydrochloric acid were added to separate the layers. The ethyl acetate layer was concentrated, and the obtained crude crystals were purified by column chromatography to obtain the compound 2-a represented by the following formula: 13.7 g.

[0165]

[Chemical 21]

The obtained compound 2-a was identified by ¹ H-NMR. The data are shown below. ¹ H-NMR (CDCl ₃ , 300 MHz) δ: 7.98
(D, 1H), 7.16 (d, 1H), 6.70 (d,
1H), 6.62 (s, 1H), 6.50 (s, 1
H), 6.46 (d, 1H), 4.05 (t, 2H),
3.96 (t, 2H), 3.64 (t, 2H), 2.7
0 (t, 2H), 2.02 (t, 2H), 1.84
(M, 4H), 1.63 (m, 1H), 1.43 (m,
2H), 1.24-1.36 (m, 8H), 1.16
(M, 2H), 0.99 (d, 3H), 0.98 (t,
3H), 0.89 (s, 9H)

Next, reduced iron: 7.3 g, ammonium chloride: 0.7 g, isopropanol: 50 ml and water:
The mixture was added to a mixed solvent of 15 ml and heated under reflux, and compound 2-a (13.6 g) was added thereto in portions. After heating under reflux for 60 minutes, the reaction solution was filtered through Celite. Ethyl acetate and water were added to the filtrate for liquid separation, and the ethyl acetate layer was concentrated to obtain compound 2-b represented by the following formula.

[0168]

[Chemical formula 22]

The compound 2-b was dissolved in 50 ml of methanol, concentrated hydrochloric acid (7 ml) was added, and the mixture was cooled to 0 ° C. Sodium nitrite: 2.0g and water: 5ml
The solution consisting of and was added dropwise, and the mixture was stirred at 10 ° C. for 1 hour, potassium hexafluorophosphate (6.2 g) was added to the reaction mixture, and the mixture was stirred at room temperature for 90 minutes. 50 ml of isopropanol and 100 ml of water were added thereto for crystallization. The precipitated crystals were collected by filtration, washed successively with water and isopropanol, and then recrystallized from a mixed solvent of ethyl acetate and isopropanol. After drying, Exemplified Compound A-2 was added to 12.
1 g was obtained.

[0170]

[Chemical formula 23]

The diazonium salt A-2 thus obtained was converted into ¹ H--N
It was identified by MR. The data are shown below. ¹ H-NMR (CDCl ₃ , 300 MHz) δ: 7.84
(D, 1H), 7.20 (d, 1H), 6.86 (d,
1H), 6.79 (s, 1H), 6.78 (d, 1)
H), 6.58 (s, 1H), 4.13 (t, 2H),
3.96 (t, 2H), 3.86 (t, 2H), 2.7
0 (t, 2H), 2.12 (m, 2H), 1.60-
1.91 (m, 5H), 1.43 (m, 2H), 1.2
6-1.38 (m, 8H), 1.20 (m, 2H),
0.99 (d, 3H), 0.90 (t, 3H), 0.8
9 (s, 9H) Further, the maximum absorption wavelength (λmax) in the ultraviolet-visible absorption spectrum in methanol was 418 nm, and the extinction coefficient ε was 2.5 × 10 ⁴ .

Example 3 In Example 3, a thermal recording material M ₁ using the diazonium salt of the present invention was prepared below.

(Preparation of Phthalated Gelatin Aqueous Solution) 32 parts by mass of phthalated gelatin (trade name: MGP gelatin, manufactured by Nibbi Colleggen Ltd.) and 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Kagaku Kogyo Co., Ltd. 0.9143 parts by mass and deionized water 36
7.1 parts by mass were mixed and dissolved at 40 ° C. to obtain a phthalated gelatin aqueous solution.

(Preparation of Alkali-treated Gelatin Aqueous Solution) 25.5 parts by mass of alkali-treated low-ionic gelatin (trade name: # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.)
-Benzothiazolin-3-one (3.5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd.) 0.7286 parts by mass;
0.153 parts by mass of calcium hydroxide and 1 ion-exchanged water
43.6 parts by mass were mixed and dissolved at 50 ° C. to obtain an alkali-treated gelatin aqueous solution.

[0175] (the diazonium salt encapsulated micro Preparation of Capsule Solution L _a) ethyl acetate 16.1 g, and the diazonium salt (A-1) 4.3 g obtained in Example 1, and tricresyl phosphate 9.2 g, Diphenyl (2,4
6-trimethylbenzoyl) phosphine oxide (trade name: Lucillin TPO, BASF Japan Ltd.)
4 g and were added and mixed uniformly. Then, a mixture of xylylene diisocyanate / trimethylpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material (trade name: Takenate D119N (50% by mass ethyl acetate solution), Takeda Pharmaceutical Co., Ltd. (Manufactured by Kogyo Co., Ltd.) and 8.6 g were added and mixed to obtain solution I. Then, the above phthalated gelatin aqueous solution: 56.
5g, ion-exchanged water: 16.5g, Scrap
AG-8 (50% by mass, manufactured by Nippon Seika Co., Ltd.): 0.35
The above-mentioned solution I was added to the mixed solution of g and, and emulsified and dispersed at 40 ° C. and 10,000 rpm using a homogenizer. After 20 g of water was added to the obtained emulsion to homogenize it, an encapsulation reaction was carried out at 40 ° C. for 3 hours while stirring. afterwards,
Ion exchange resin Amberlite IRC50 (manufactured by Organo Corporation) (8.2 g) was added, and the mixture was further stirred for 1 hour. Removed by filtration ion exchange resin, and the concentration adjusted so that the solid concentration of the capsule solution is 20.0% to obtain a diazonium salt-containing microcapsule solution L _a. The particle size of the obtained microcapsules was measured by a particle size measurement (LA-700, manufactured by Horiba, Ltd.), and the median diameter was 0.56 μ.
It was m.

(Preparation of coupler emulsion L _b ) 9.9 g of coupler (B-1) and 9.9 g of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.) in 33.0 g of ethyl acetate.
4 '-(m-phenylene diisopropylidene) diphenol (Brand name: Bisphenol M (Mitsui Petrochemical Co., Ltd.)
20.8 g, 3,3,3 ′, 3′-tetramethyl-
5,5 ', 6,6'-tetra (1-propoxy) -1,
3.3 g of 1'-spiroindane (manufactured by Sankyo Chemical Co., Ltd.),
4- (2-Ethyl-1-hexyloxy) benzenesulfonic acid amide (Manac Co., Ltd.) 13.6 g, 4-n
-Dissolve 6.8 g of pentyloxybenzene sulfonic acid amide (manufactured by Manac Co., Ltd.), 4.3 g of calcium dodecylbenzene sulfonate (trade name: Pionin A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) II
A liquid was obtained. Separately the above alkali-treated gelatin aqueous solution 20
While mixing 6.3 g with ion-exchanged water 107.5 g,
Add solution II and use a homogenizer at 40 ° C for 10
It was emulsified and dispersed at 000 rpm for 10 minutes. After removing the ethyl acetate by heating the obtained emulsion under reduced pressure, the solid content concentration becomes 2
The concentration was adjusted to 6.5% by mass. The particle size of the obtained coupler emulsion was measured by a particle size measurement (LA-700, measured by Horiba, Ltd.), and the median size was 0.21.
It was a micrometer. To this, 9 g of SBR latex (trade name: SN-307, 48% by mass solution, manufactured by Sumika AB S Latex Co., Ltd.) having a concentration adjusted to 26.5% by mass was added to give a coupler emulsion L _b . Obtained.

(Preparation of coating liquid L _c for heat-sensitive recording layer) Diazonium salt-containing microcapsule liquid L _a and coupler emulsion L _b
9.5 g was mixed so that the mass ratio of the coupler / diazonium salt compound would be 2.2 / 1 to obtain a thermal recording layer coating liquid L _c .

(Preparation of coating liquid L _d for light transmittance adjusting layer) Preparation of Ultraviolet Absorber Precursor Microcapsule Liquid In 71 parts by mass of ethyl acetate, [2-allyl-6- (2H-benzotriazole-2-
Yl) -4-t-octylphenyl] benzenesulfonate 14.5 parts by mass, 2,2′-t-octylhydroquinone 5.0 parts by mass, tricresyl phosphate 1.9 parts by mass, and α-methylstyrene dimer. (Product name: MSD-
100, 5.7 parts by mass of Mitsui Chemicals, Inc. and calcium dodecylbenzene sulfonate (trade name: Pionine A-)
41-C (70% methanol solution), Takemoto Yushi Co., Ltd.
(Manufactured by) and 0.45 parts by mass were uniformly dissolved. In this mixed liquid, xylylene diisocyanate /
Trimethylolpropane adduct (trade name: Takenate D
110N (75% by mass ethyl acetate solution) and 54.7 parts by mass of Takeda Pharmaceutical Co., Ltd. were added and uniformly stirred to obtain an ultraviolet absorber precursor mixed liquid.

Separately, 52 parts by mass of itaconic acid-modified polyvinyl alcohol (trade name: KL-318, manufactured by Kuraray Co., Ltd.), 8.9 parts by mass of 30% by mass phosphoric acid aqueous solution, and 532.6 parts by mass of ion-exchanged water. Were mixed to prepare a PVA aqueous solution for the UV absorber precursor microcapsule solution. UV absorber precursor microcapsule solution PVA aqueous solution 51
The above ultraviolet absorber precursor mixed solution was added to 6.06 parts by mass, and the mixture was emulsified and dispersed at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). After adding 254.1 parts by mass of ion-exchanged water to the obtained emulsion and homogenizing it, 40
The encapsulation reaction was performed for 3 hours with stirring at ℃. Then, 94.3 parts by mass of ion exchange resin Amberlite MB-3 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Then, the ion exchange resin was filtered off, and the concentration of the solid content of the capsule liquid was adjusted to 13.5%. The particle size of the obtained microcapsules was measured by the particle size measurement (L
As a result of A-700, measured by Horiba, Ltd.), the median diameter was 0.23 ± 0.05 μm. In this capsule liquid 859.1 parts by mass, 2.416 parts by mass of carboxy-modified styrene butadiene latex (trade name: SN-307, (48% by mass aqueous solution), manufactured by Sumitomo Nogatac Co., Ltd.) and 39. parts of ion-exchanged water. 5 parts by mass were mixed to obtain an ultraviolet absorber precursor microcapsule liquid.

2. Preparation of coating liquid L _d for light transmittance adjusting layer The above-mentioned UV absorber precursor microcapsule liquid L _d 100
0 parts by mass and a fluorosurfactant (trade name: Megafac F-120, Dainippon Ink and Chemicals, Inc., 5% by mass)
Aqueous solution) 5.2 parts by mass, 4% by mass aqueous sodium hydroxide solution 7.75 parts by mass, and sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% by mass). Aqueous solution) 73.39 parts by mass,
Were mixed to obtain a coating liquid L _d for a light transmittance adjusting layer.

(Preparation of coating liquid L _e for protective layer) 1. Preparation of polyvinyl alcohol solution for protective layer Vinyl alcohol-alkyl vinyl ether copolymer (trade name: EP-130, manufactured by Denki Kagaku Kogyo Co., Ltd.) 16
0 parts by mass and 8.74 parts by mass of a mixed solution of sodium alkylsulfonate and polyoxyethylene alkyl ether phosphate (trade name: Neoscore CM-57 (54% by mass aqueous solution), manufactured by Toho Chemical Industry Co., Ltd.) , And 3832 parts by mass of ion-exchanged water were mixed and dissolved at 90 ° C. for 1 hour to obtain a uniform polyvinyl alcohol solution for protective layer.

2. Preparation of Pigment Dispersion Liquid for Protective Layer 8 parts by mass of barium sulfate (trade name: BF-21F, barium sulfate content 93% or more, manufactured by Sakai Chemical Industry Co., Ltd.) was added with anionic special polycarboxylic acid type polymer activity. Agent (trade name:
Poise 532A (40% by mass aqueous solution), manufactured by Kao Corporation
0.2 parts by mass and 11.8 parts by mass of ion-exchanged water were mixed and dispersed with a Dynomill. As a result of particle size measurement (LA-910, manufactured by Horiba, Ltd.), this dispersion was
The median diameter was 0.15 μm or less. To 45.6 parts by mass of the obtained dispersion liquid, colloidal silica (trade name:
8.1 parts by mass of Snowtex O (20% by mass aqueous dispersion, manufactured by Nissan Kagaku Co., Ltd.) was added to obtain a target pigment dispersion for a protective layer.

3. Preparation of Matting Agent Dispersion for Protective Layer Wheat Starch (trade name: Wheat Starch S, Shinshin Food Industry Co., Ltd.)
Manufactured by K.K.), an aqueous dispersion of 1-2 benzisothiazoline 3-one (trade name: PROXEL BD, I.D.
C. I (manufactured by I) 3.81 parts by mass and ion-exchanged water 19
76.19 parts by mass were mixed and uniformly dispersed to obtain a protective layer matting agent dispersion.

4. Preparation of Coating Blend Solution for Protective Layer 1000 parts by mass of the polyvinyl alcohol solution for protective layer was added to a fluorosurfactant (trade name: Megafac F-1).
20, Dainippon Ink and Chemicals, Inc., 5 mass% aqueous solution)
40 parts by mass, 50 parts by mass of sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (2.0% by mass aqueous solution manufactured by Sankyo Chemical Co., Ltd.), and 49.87 parts by mass of the pigment dispersion liquid for the protective layer. 16.65 parts by mass of the matting agent dispersion for the protective layer, and 48.7 parts of zinc stearate dispersion (trade name: Hydrin F115, 20.5% by mass aqueous solution, manufactured by Chukyo Yushi Co., Ltd.). The mixture was uniformly mixed to obtain a coating liquid for protective layer (coating liquid for protective layer _Le ).

(Preparation of Support with Undercoat Layer) 1. Preparation of coating liquid for undercoat layer Enzyme-decomposed gelatin (average molecular weight: 10,000, PAGI
40 parts by mass of method viscosity: 1.5 mPa · s (15 mP), PAGI method jelly strength: 20 g) was added to 60 parts by mass of ion-exchanged water, and dissolved by stirring at 40 ° C. to prepare a gelatin aqueous solution for an undercoat layer. Separately, 8 parts by mass of water-swelling synthetic mica (aspect ratio: 1000, trade name: Somasif ME100, manufactured by Coop Chemical Co., Ltd.) and 92 parts by mass of water are mixed and then wet-dispersed with Viscomill to obtain a volume average particle size. 2.0
A mica dispersion of μm was obtained. Water was added to this mica dispersion so that the mica concentration was 5% by mass, and the mixture was uniformly mixed to prepare a desired mica dispersion.

Next, 120 parts by mass of water and 556 parts by mass of methanol were added to 100 parts by mass of the above 40% by mass aqueous gelatin solution for undercoat layer at 40 ° C., and the mixture was sufficiently stirred and mixed, and then the above-mentioned 5% by mass mica dispersion 208 was added. Then, 1 part by mass of polyethylene oxide-based surfactant was added, and 9.8 parts by mass of polyethylene oxide-based surfactant was added. Then, the liquid temperature was maintained at 35 ° C to 40 ° C, and 7.3 parts by mass of an epoxy compound gelatin hardener was added to the undercoat layer coating liquid (5.
7% by mass) was prepared.

2. Preparation of support with undercoat layer Wood pulp consisting of 50 parts by weight of LBPPS and 50 parts by weight of LBPK was beaten to a Canadian freeness of 300 ml with a double disc refiner to give 0.5 parts by weight of epoxidized behenamide and 1.0 part of anionic polyacrylamide. Parts by mass, 1.0 part by mass of aluminum sulfate, 0.1 part by mass of polyamide polyamine epichlorohydrin, and 0.5 part by mass of cationic polyacrylamide,
Was added at an absolutely dry mass ratio to pulp, and a base paper having a basis weight of 114 g / m ² was made into paper by a Fourdrinier paper machine, and the thickness was adjusted to 100 μm by calendering.

After performing corona discharge treatment on both sides of the above base paper, polyethylene was applied to a resin thickness of 36 μm using a melt extruder.
To form a resin layer composed of a matte surface (this surface is referred to as "back surface"). Next, using a melt extruder, a polyethylene resin containing 10% by mass of anatase-type titanium dioxide and a trace amount of ultramarine blue was coated on the surface opposite to the back surface on which the resin layer was formed to a resin thickness of 50 μm. Then, a resin layer composed of a glossy surface was formed (this surface is referred to as "front surface"). After the corona discharge treatment on the polyethylene resin coated surface of the back side, aluminum oxide (trade name: alumina sol 100, as an antistatic agent
Nissan Chemical Co., Ltd.) / Silicon dioxide (trade name: Snowtex O, Nissan Chemical Co., Ltd.) = 1/2 (mass ratio) is dispersed in water, and the mass after drying is 0.2 g. / M ²
Was applied so that Next, after the corona discharge treatment was applied to the polyethylene resin-coated surface of the front surface, mica containing the above-mentioned coating solution for undercoat layer was applied so that the coating amount was 0.26 g / m ^2, and the support with the undercoat layer was applied. Obtained.

(Coating) On the undercoat layer of the above-mentioned support with undercoat layer, the thermosensitive recording layer coating solution L _c , the light transmittance adjusting layer coating solution L _d , and the protective layer coating solution _{Le in} the order of 3 Layers simultaneously and continuously applied, 30 ° C, 30% RH, and 40 ° C, 30
It was dried continuously under the condition of% RH to obtain a heat-sensitive recording material M ₁ of Example 3.

[Evaluation] (Coloring test) Kyocera thermal head (KST
Type), the recording energy per unit area is 50 m
The electric power applied to the thermal head and the pulse width were determined so as to be J / mm ^2, and the thermal recording material M ₁ obtained above was thermally printed to obtain an image. After that, in the obtained image,
The film was exposed to an ultraviolet lamp having an emission center wavelength of 420 nm and an output of 40 W for 11 seconds, and the color density (image density of color area) and the background density (density of non-image area) were measured. In this color development test, the color development density and the background density are Mac
The density at the Y position was measured using bethRD918. The results are shown in Table 1 below.

(Light Fixing Property Test) Unprinted thermal recording material M
₁ was exposed to an ultraviolet lamp with an emission center wavelength of 420 nm and an output of 40 W for 7 seconds, and then, in the same manner as in the above color development test,
The color density was measured after thermal printing to obtain an image. The results are shown in Table 1 below.

(Preservation test) Unprinted thermal recording material M ₁
After being forcibly stored for 72 hours under the conditions of 60 ° C. and 30% RH, thermal printing was carried out in the same manner as in the above color development test to obtain an image, and then the color density was measured. The results are shown in Table 1 below.

Example 4 Example 4 was repeated except that the exemplified compound (A-2) obtained in Example 2 was used as the diazonium salt instead of the exemplified compound (A-1). A thermal recording material M ₂ was prepared. Further, the produced thermal recording material M ₂ was subjected to a color development test, a photofixability test and a storability test in the same manner as in Example 3. The results are also shown in Table 1 below.

[Comparative Example 1] A thermosensitive recording material was prepared in the same manner as in Example 3 except that the comparative compound (R-1) having the following structure was used as the diazonium salt instead of the exemplified compound (A-1). to prepare a M _3. The prepared thermal recording material M ₃
In the same manner as in Example 3, the color development test, the photofixability test, and the storage stability test were performed. The results are also shown in Table 1 below.

[0195]

[Chemical formula 24]

[Comparative Example 2] A thermosensitive recording material was prepared in the same manner as in Example 3 except that the comparative compound (R-2) having the following structure was used as the diazonium salt instead of the exemplified compound (A-1). M ₆ was prepared. Prepared thermal recording material M ₄
In the same manner as in Example 3, the color development test, the photofixability test, and the storage stability test were performed. The results are also shown in Table 1 below.

[0197]

[Chemical 25]

[0198]

[Table 1]

From the results shown in Table 1, the thermal recording material M of the present invention was obtained.
₁ and M ₂ indicate that the color density after photo-fixing is low and the photo-fixing property is excellent as compared with the heat-sensitive recording materials M ₃ and M ₄ of the comparative examples. As a result, the diazonium salt of the present invention as the color-forming component of the thermal recording materials M ₁ and M ₂ is
It was found that it has excellent photo-fixing property (photo-decomposability) and its decomposition rate is fast. Further, the heat-sensitive recording materials M ₁ and M ₂ can obtain sufficient color density, and the heat-sensitive recording material M of the comparative example can be obtained.
_The background density could be suppressed to be low as compared with ₃ and M ₄ . Further, it was found that the thermal recording materials M ₁ and M ₂ have higher storability than the thermal recording material M ₄ of Comparative Example 2.

[0200]

INDUSTRIAL APPLICABILITY The present invention can provide a novel diazonium salt having a maximum absorption wavelength (λmax) of more than 400 nm. Further, the present invention can provide a heat-sensitive recording material using the diazonium salt, which is excellent in photofixability with a light source having a wavelength longer than 400 nm, is excellent in storage stability, and has less background coloring.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H026 AA07 AA32 BB42 BB43 DD01                       DD23 DD48 DD53 FF05                 4C031 AA04

Claims (7)

[Claims] 1. A diazonium salt represented by the following general formula (1): [Chemical 1] [In the general formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group. Represents R ⁵ ,
R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an aryl group, an acyl group or an alkoxycarbonyl group. R ⁵ and R ⁷ , R ⁵ and R ⁸ , R
⁶ and R ⁷ , R ⁶ and R ⁸ , R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸ and R ^9, and R ⁸ and R ¹⁰ may be bonded to each other to form a ring. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently
Hydrogen atom, halogen atom, alkyl group, alkoxy group,
It represents an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group, and a cyano group.
X ⁻ represents an anion. ] 2. The diazonium salt according to claim 1, wherein the diazonium salt is represented by the following general formula (2). [Chemical 2] [In the general formula (2), R ¹ represents a hydrogen atom, a halogen atom,
Represents an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, or an arylsulfonyl group, wherein R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom or an alkyl group. Represents an aryl group. R ⁵ and R ⁷ , R ⁵ and R ⁸ , R ⁶ and R ⁷ , R ⁶ and R ⁸ ,
R ⁷ and R ⁹ , R ⁷ and R ¹⁰ , R ⁸ and R ^9, and R ⁸ and R ¹⁰ may combine with each other to form a ring. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom,
It represents an alkyl group, an alkoxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, an alkoxycarbonyl group, a carbamoyl group or a cyano group. X ⁻ represents an anion. ] 3. A heat-sensitive recording material having a heat-sensitive recording layer containing a diazonium salt and a coupler on the surface of a support, wherein the diazonium salt is the diazonium salt according to claim 1. Recording material. 4. The heat-sensitive recording material according to claim 3, wherein the diazonium salt is the diazonium salt according to claim 2. 5. The heat-sensitive recording material according to claim 3, wherein the coupler is a compound represented by the following general formula (3) or a tautomer thereof. [Chemical 3] [In the general formula (3), E ¹ and E ² are each independently
Represents an electron-withdrawing group. Further, E ¹ and E ² may combine with each other to form a ring. ] 6. The heat-sensitive recording material according to claim 3, wherein the diazonium salt is encapsulated in microcapsules. 7. The capsule wall of the microcapsule comprises:
7. The heat-sensitive recording material according to claim 6, which contains polyurethane and / or polyurea.