JP2005067132A - Thermosensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive recording material, which is excellent in color developing properties and ground preservability and, in the image (especially the white image part) after printing of which, stains are prevented from developing. <P>SOLUTION: In this thermosensitive recording material, a thermosensitive recording layer including a diazo compound and a coupler is provided on a support and, at the same time, the diazo compound is involved in microcapsules formed through the polymerization between a compound with active hydrogens and an isocyanate compound. The diazo compound is a compound expressed by general formula (1). The isocyanate compound is a reaction product between a multifunctional isocyanate compound and a polyether derivative with a terminal amino group expressed by general formula (2). At least one among R<SP>3</SP>, R<SP>4</SP>, R<SP>5</SP>and R<SP>6</SP>in general formula (1) expresses -N<SB>2</SB><SP>+</SP>X<SP>-</SP>. The letter A in general formula (2) expresses an aryl group or an alkyl group and L expresses an alkylene group. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material having a heat-sensitive recording layer containing a diazo compound encapsulated in microcapsules and a coupler, and more particularly to a heat-sensitive recording material excellent in color development and storage stability.

  A diazonium salt is generally a compound having a very high chemical activity, and readily reacts with a compound called a coupler having a phenol derivative or an active methylene group to easily form an azo dye. The diazonium salt also has photosensitivity, has the property of decomposing by light irradiation and losing its activity, and has been used for a long time as an optical recording material typified by diazocopy (for example, (Refer nonpatent literature 1.).

These recording materials using a diazonium salt as a color forming component have a very high chemical activity of the diazonium salt. For this reason, even in a dark place, the diazonium salt gradually undergoes thermal decomposition and loses its reactivity, so that it has the disadvantage that the shelf life as a recording material is short. Further, in the background portion which is a non-image portion, the residual diazonium salt compound is decomposed at the time of photofixing, and the non-image portion is colored due to the generation of the colored decomposition product (stain). Further, even in a completed image after fixing, the non-image portion has low light resistance, and there is a disadvantage that coloring is increased when left for a long time under sunlight or a fluorescent lamp.
Further, improvement in recording speed has been studied as a long-standing problem, and there has been a demand for a diazonium salt that improves photofixability and can be photofixed in a short time.

  As means for improving the instability of such a diazonium salt, various methods have been proposed so far. As one of the most effective means, there is a method of encapsulating a diazonium salt in a microcapsule. By microencapsulating the diazonium salt, the diazonium salt is isolated from substances that promote decomposition such as water and base, so that recording materials using this can dramatically improve the shelf life (for example, non- (See Patent Document 2).

  However, although the stability as a thermosensitive recording material is dramatically improved, the instability caused by the diazonium salt itself is not completely suppressed, and sufficient long-term storage stability has not been achieved. . Even after printing and fixing, the photodecomposition of the diazonium salt undergoes a photodecomposition reaction when exposed to a light source for a long time, and the colored stain increases with the reaction, resulting in a non-image after photofixing. There is also a problem that the whiteness of the portion (background portion) is lowered and the contrast with the coloring portion is also lowered.

  Furthermore, the photodecomposition reaction as described above cannot occur uniformly, and it is known that various decomposition products are generated depending on the surrounding environment. This produces a product called absorption stain, which has an absorption especially in the visible region. If the stain is remarkably generated, the whiteness of the non-image area (background area) after photofixing is lowered and the contrast with the color development area is also lowered. As a result, the commercial value of the recording material itself is significantly impaired.

  On the other hand, in order to include diazonium salt compounds in microcapsules, these compounds are generally dissolved in an organic solvent (oil phase) and added to an aqueous solution of a water-soluble polymer (aqueous phase) to be emulsified and dispersed. The method is known. At this time, by adding a monomer or prepolymer as a wall material to either the oil phase side or the water phase side, a polymer wall is formed at the interface between the oil phase and the water phase to make microcapsules. (See, for example, Non-Patent Documents 3 and 4.)

  In the case of a microcapsule having a polyurethane or polyurea wall, in order to form a microcapsule, first, a diazonium salt is dissolved in an organic solvent, a polyvalent isocyanate compound is added thereto, and the organic phase solution is dissolved in a water-soluble polymer. After emulsification in an aqueous solution, a polymerization reaction promoting catalyst is added to the aqueous phase, or the temperature of the emulsion is increased to polymerize the polyvalent isocyanate compound with a compound having active hydrogen such as water to form a capsule wall. Methods are conventionally known.

As the polyurea compound which is a material for forming the above polyurea or polyurethane wall, for example, an adduct of 2,4-tolylene diisocyanate and trimethylolpropane and an adduct of xylylene diisocyanate and trimethylolpropane are mainly used. (For example, refer to Patent Documents 1 and 2.)
However, even a polyurea or polyurethane capsule wall using a polyisocyanate compound as described above cannot have a sufficiently long shelf life when the above-described diazonium salt compound is used. In addition, when a thermal recording material having a shelf life that is not sufficiently long is exposed to high-temperature and high-humidity conditions, for example, when it is exposed to high temperatures and high humidity, the background color development called “fogging” occurs, and the printed image Reduce visibility. In order to solve such a problem, there is a means for increasing the wall thickness of the microcapsule, for example. However, when such a method is used, the color development sensitivity at the time of thermal printing is lowered. Thus, it was very difficult to further improve the shelf life while maintaining high color development.

  The multi-color heat-sensitive recording material is provided with cyan, magenta and yellow heat-sensitive recording layers, and these are printed by applying different heating temperatures. Compared to the above, further excellent thermal responsiveness is required. However, conventional polyurea or polyurethane capsule walls are difficult to satisfy this requirement.

  A thermal sensitizer can be added to the thermosensitive coloring layer of the thermosensitive recording material in order to improve thermal sensitivity. However, since such a heat sensitizer is usually a crystalline substance, an emulsion containing the heat sensitizer may cause problems such as precipitation of crystals over a long period of time. Development of a microcapsule having sufficient heat sensitivity without using or using a small amount is desired.

  In view of such problems, an adduct of a compound having one active hydrogen in the molecule and an average molecular weight of 500 to 20,000 and a polyfunctional isocyanate having two or more isocyanate groups in the molecule is included. A heat-responsive microcapsule made of a polymer obtained by polymerization of an isocyanate compound and having both fog and sensitivity has been proposed (for example, see Patent Document 3). However, as the functional group having active hydrogen, a hydroxyl group or amino group is exemplified, and a polyether derivative is exemplified in the specification for a compound having an average molecular weight of 500 to 20,000. Only polyether derivatives whose functional groups are hydroxyl groups are described. In addition, in the description of the examples, stannous octylate is added to increase the reaction activity during the reaction of the polyether derivative whose functional group having active hydrogen is a hydroxyl group and the polyfunctional isocyanate, and remains. There are concerns about the toxicity of tin compounds. Accordingly, a polyether derivative having an active hydrogen that reacts with a polyfunctional isocyanate without adding a tin compound has been desired.

Also proposed is a microcapsule having a polyurea shell, wherein the isocyanate used in the production of the microcapsule is a reaction product of at least a difunctional isocyanate and a monovalent poly (ethylene oxide) alcohol. (For example, refer to Patent Document 4). However, in order to synthesize the reaction product, a high temperature of 110 ° C. is applied, which is problematic in terms of energy efficiency.
Japanese Unexamined Patent Publication No. Sho 62-212190 JP-A-4-26189 Japanese Patent Laid-Open No. 10-114153 Japanese Patent No. 3266330 Edited by the Japan Photographic Society, “Basics of Photographic Engineering: Non-Silver Salt Photo Edition”, Corona, 1982, p. 89-P117, p. 182-P201 Usami Tomomasa et al., “Journal of Electrophotographic Society”, Vol. 26, No. 2, 1987, p. 115-125 Asahi Kondo "Microcapsule", Nikkan Kogyo Shimbun, 1970 Kondo et al. “Microcapsules”, Sankyo Publishing, 1977

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a heat-sensitive recording material that has excellent color developability and background preservation, and suppresses the occurrence of stain in an image after printing (particularly, a white image portion).

The above problems are solved by the following microcapsules and heat-sensitive recording material of the present invention.
That is, the present invention
<1> A thermosensitive recording layer containing a diazo compound and a coupler is provided on a support, and the diazo compound is encapsulated in a microcapsule formed by polymerizing a compound having active hydrogen and an isocyanate compound. In the heat-sensitive recording material, the diazo compound is a compound represented by the following general formula (1), and the isocyanate compound is a polyfunctional isocyanate compound and a terminal amino group represented by the following general formula (2). It is a heat sensitive recording material characterized by being a reaction product with a polyether derivative having

(In the general formula (1), R ¹ represents a hydrogen atom, an alkyl group or an aryl group. R ² represents an alkyl group or an aryl group. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently selected. Represents a hydrogen atom or a monovalent substituent, provided that at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ^−, and X ⁻ represents an anion.)

(In general formula (1), X represents a single bond, —CO— or —SO ₂ —. A represents an aryl group or an alkyl group. M represents 2 or 3. L represents an alkylene group. R represents an alkyl group, an aryl group, or an acyl group, and n represents 10 to 500.)

<2> The heat-sensitive recording material according to <1>, wherein in the general formula (1), R ⁵ is —N ₂ ⁺ X ⁻ and R ⁴ is an alkoxy group or an aryloxy group. .
<3> The heat-sensitive recording material according to <1> or <2>, wherein in general formula (2), A is an aryl group and m is 2.

<4> The heat-sensitive recording material according to any one of <1> to <3>, wherein the coupler is a compound represented by the following general formula (3) or a tautomer thereof. is there.

(In General Formula (3), E ¹ and E ² each independently represent an electron-withdrawing group. E ¹ and E ² may be bonded to each other to form a ring.)

  According to the present invention, it is possible to provide a heat-sensitive recording material that has excellent color developability and background preservation, and suppresses the occurrence of stain in an image after printing (particularly a white image portion).

  The heat-sensitive recording material of the present invention has a heat-sensitive recording layer containing a diazo compound represented by the following general formula (1) (hereinafter sometimes referred to as “diazo compound in the present invention”) and a coupler on a support. The diazo compound is formed by polymerizing a compound having active hydrogen and an isocyanate compound, and the isocyanate compound has a polyfunctional isocyanate compound and a terminal amino group represented by the following general formula (2). It is characterized by being encapsulated in microcapsules (hereinafter sometimes referred to as “microcapsules in the present invention”), which are reaction products with the polyether derivative.

（一般式（１）中、Ｒ¹は、水素原子、アルキル基またはアリール基を表す。Ｒ²は、アルキル基またはアリール基を表す。Ｒ³、Ｒ⁴、Ｒ⁵およびＲ⁶は、それぞれ独立に、水素原子または一価の置換基を表す。但し、Ｒ³、Ｒ⁴、Ｒ⁵およびＲ⁶のうち少なくとも一つは−Ｎ₂ ⁺Ｘ^-を表す。Ｘ^-はアニオンを表す。）

(In the general formula (1), R ¹ represents a hydrogen atom, an alkyl group or an aryl group. R ² represents an alkyl group or an aryl group. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently selected. Represents a hydrogen atom or a monovalent substituent, provided that at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ^−, and X ⁻ represents an anion.)

(In General Formula (2), X represents a single bond, —CO— or —SO ₂ —. A represents an aryl group or an alkyl group. M represents 2 or 3. L represents an alkylene group. R represents an alkyl group, an aryl group, or an acyl group, and n represents 10 to 500.)

According to the heat-sensitive recording material of the present invention, the microcapsules of the present invention, which have excellent storage stability and color developability, encapsulate the diazo compound of the present invention, which is excellent in fixing and color developability and difficult to fog, thereby providing color developability and background preservation. And the occurrence of stains in the image area (particularly the white image area) after printing can be suppressed. In particular, the heat-sensitive recording material of the present invention is useful as a multicolor heat-sensitive recording material having a plurality of heat-sensitive recording layers. This is because, according to the present invention, the diazo compound can be sufficiently fixed when the first color or the second color is developed. Therefore, the heat sensitivity after fixing by the heat for developing the second color or the third color. This is because coloring of the recording layer can be prevented.
Hereinafter, the heat-sensitive recording material of the present invention will be described in detail.

<Thermal recording layer>
The heat-sensitive recording layer in the present invention contains the diazo compound in the present invention encapsulated in the microcapsules in the present invention and a coupler, and can contain an organic base and other additives as necessary.

(Diazo compound)
The diazo compound in the present invention is a compound represented by the following general formula (1).

In general formula (1), R ¹ represents a hydrogen atom, an alkyl group, or an aryl group. R ² represents an alkyl group or an aryl group. R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ . X ⁻ represents an anion.

The alkyl group represented by R ¹ may be unsubstituted or substituted, and examples of the substituent introduced into the alkyl group include an aryl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxyl group, a sulfonyl group, and a heterocyclic residue are preferable.

The alkyl group represented by R ¹ is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 20 carbon atoms. Specifically, methyl group, ethyl group, butyl group, hexyl group, octyl group, 2-ethylhexyl group, 3,5,5-trimethylhexyl group, dodecyl group, octadecyl group, benzyl group, (4-ethoxyphenyl) Methyl group, N, N-diethylcarbamoylmethyl group, N, N-dibutylcarbamoylmethyl group, 1- (N, N-dibutylcarbamoyl) ethyl group, 2-methoxyethyl group, 1-methyl-2-phenoxyethyl group, (4-chlorophenyl) methyl group and (2,4-dichlorophenyl) methyl group are preferable, and ethyl group, butyl group, hexyl group, benzyl group, N, N-diethylcarbamoylmethyl group, N, N-dibutylcarbamoylmethyl group, 1- (N, N-dibutylcarbamoyl) ethyl group, 1-methyl-2-phenoxyethyl group, (4-alkyl Rofeniru) methyl group, (2,4-dichlorophenyl) methyl group is particularly preferred.

The aryl group represented by R ¹ may be unsubstituted or substituted, and examples of the substituent introduced into the alkyl group include an alkyl group, a halogen atom, an alkoxy group, and an aryloxy group. An alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxyl group, a sulfonyl group, and a heterocyclic residue are preferable.
The aryl group represented by R ¹ is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 1 to 20 carbon atoms. Specifically, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-phenylphenoxy group, 4-chlorophenyl group, 2-methoxyphenyl group, 3-ethoxyphenyl group, 4 -Butoxyphenyl group, 2,4-diethoxyphenyl group, 2,5-dibutoxyphenyl group, 4-phenoxyphenyl group, naphthyl group, 4-dibutylcarbamoylphenyl group, 4-dibutylsulfamoylphenyl group are preferred, A phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-chlorophenyl group, 2-methoxyphenyl group, 3-ethoxyphenyl group, and 4-butoxyphenyl group are particularly preferable.

R ² represents an alkyl group or an aryl group, and has the same meaning as the alkyl group or aryl group represented by R ¹ , and preferred specific examples are also the same.

R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or a monovalent substituent. However, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ . —N ₂ ⁺ represents a diazonio group, and X ⁻ represents an anion.

Examples of the monovalent substituent represented by R ³ , R ⁴ , R ⁵ and R ⁶ include an alkyl group, an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, and an alkoxy group. A carbonyl group, a carbamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, and a sulfamoyl group are preferable, and a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, and a sulfonylamino group The group or N ₂ ⁺ X ⁻ is preferred, but as mentioned above, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ .

The alkyl group and aryl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ have the same meaning as in R ¹ , and preferred specific examples are also the same.

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

The alkoxy group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably an alkoxy group having 1 to 30 carbon atoms in total, having 1 carbon atom in total. More preferred are ˜20 alkoxy groups. Specifically, for example, methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, 2-ethylhexyloxy group, 3,5,5-trimethylhexyloxy group, octyloxy group, decyloxy group, 2-phenoxy An ethoxy group, 2- (3,5-di-t-butylphenoxy) ethoxy group, dibutylcarbamoylmethoxy group, hexadecyloxy group, and octadecyloxy group are preferable, methoxy group, ethoxy group, butoxy group, hexyloxy group, 2 -Ethylhexyloxy group, 3,5,5-trimethylhexyloxy group, 2-phenoxyethoxy group, and dibutylcarbamoylmethoxy group are more preferable.

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

The alkylthio group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably an alkylthio group having 1 to 30 carbon atoms in total, having 1 carbon atom in total. More preferred are ˜20 alkylthio groups. Specifically, for example, methylthio group, ethylthio group, butylthio group, hexylthio group, 2-ethylhexylthio group, 3,5,5-trimethylhexylthio group, octylthio group, decylthio group, 2-phenoxyethylthio group, 2 -(3,5-di-t-butylphenoxy) ethylthio group, dibutylcarbamoylmethylthio group, hexadecylthio group, octadecylthio group are preferred, methylthio group, ethylthio group, butylthio group, hexylthio group, 2-ethylhexylthio group, 3, More preferred are 5,5-trimethylhexylthio group, 2-phenoxyethylthio group, and dibutylcarbamoylmethylthio group.

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

The acylamino group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably an acylamino group having 1 to 30 carbon atoms in total, having 1 carbon atom in total. More preferred is an acylamino group of ˜20. Specifically, for example, formylamino group, acetylamino group, butyrylamino group, lauroylamino group, benzoylamino group, toluoylamino group, phenoxyacetyl group, (4-methoxyphenoxy) acetyl group, 2 ′, 4 ′ -Dichlorobenzoylamino group, 2 ', 4'-di-t-amylbenzoylamino group, acetylmethylamino group, benzoylmethylamino group, acetylbenzylamino group are preferred, acetylamino group, butyrylamino group, benzoylamino group, toluene More preferred are an oilamino group, a phenoxyacetyl group, a 2 ′, 4′-di-t-amylbenzoylamino group, an acetylmethylamino group, a benzoylmethylamino group, and an acetylbenzylamino group.

The alkoxycarbonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably an alkoxycarbonyl group having 2 to 30 carbon atoms in total. A C2-C20 alkoxycarbonyl group is more preferable. Specifically, for example, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, phenoxycarbonyl group, (2-ethylhexyl) oxycarbonyl group, hexyloxycarbonyl group, octyloxycarbonyl group, (4-methoxyphenyl) oxycarbonyl Group is preferable, and a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, and a phenoxycarbonyl group are particularly preferable.

The carbamoyl group represented by R ³ , R ⁴ , R ⁵ , or R ⁶ may be unsubstituted or substituted, and is preferably a carbamoyl group having 1 to 30 carbon atoms in total. More preferred are -20 carbamoyl groups. Specifically, for example, carbamoyl group, N-phenylcarbamoyl group, N-butylcarbamoyl group, N-octylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N, N-dibutylcarbamoyl Group, N, N-dihexylcarbamoyl group, N, N-diphenylcarbamoyl group, N-methyl-N-phenylcarbamoyl group, N-ethyl-N-phenylcarbamoyl group, N-methyl-N-tolylcarbamoyl group, morpholinocarbonyl group , Piperidinocarbonyl group and N, N-bis (2-methoxyethyl) carbamoyl group are preferable, N-butylcarbamoyl group, N-octylcarbamoyl group, N-phenylcarbamoyl group, N, N-diethylcarbamoyl group, N , N-dibutylcarbamoyl group, N-methyl-N Phenylcarbamoyl group is particularly preferred.

The alkylsulfonyl group represented by R ³ , R ⁴ , R ⁵ , or R ⁶ may be unsubstituted or substituted, and is preferably an alkylsulfonyl group having 1 to 30 carbon atoms in total. A C1-C20 alkylsulfonyl group is more preferable. Specifically, for example, a methylsulfonyl group, an ethylsulfonyl group, a butylsulfonyl group, a hexylsulfonyl group, and a benzylsulfonyl group are preferable, and a methylsulfonyl group and a benzylsulfonyl group are particularly preferable.

The arylsulfonyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably an arylsulfonyl group having 1 to 30 carbon atoms in total. The arylsulfonyl group having 1 to 20 is more preferable. Specifically, for example, phenylsulfonyl group, 4-methylphenylsulfonyl group, naphthylsulfonyl group, 4-methoxysulfonyl group, 4-chlorophenylsulfonyl group are preferable, methylsulfonyl group, phenylsulfonyl group, 4-methylphenylsulfonyl group. Is particularly preferred.

The sulfamoyl group represented by R ³ , R ⁴ , R ⁵ and R ⁶ may be unsubstituted or substituted, and is preferably a sulfamoyl group having 1 to 30 carbon atoms in total. More preferred are ˜20 sulfamoyl groups. Specifically, for example, sulfamoyl group, N-phenylsulfamoyl group, N, N-dimethylsulfamoyl group, N, N-diethylsulfamoyl group, N, N-dibutylsulfamoyl group, N, N-dihexylsulfamoyl group, N, N-diphenylsulfamoyl group, N-methyl-N-phenylsulfamoyl group, N-ethyl-N-phenylsulfamoyl group, N-methyl-N-tolylsulfur group Famoyl group, morpholinosulfonyl group, piperidinosulfonyl group, N, N-bis (2-methoxyethyl) sulfonyl group are preferable, sulfamoyl group, N-phenylsulfamoyl group, N, N-dibutylsulfamoyl group N, N-diphenylsulfamoyl group and N-methyl-N-phenylsulfamoyl group are particularly preferable.

In the general formula (1), it is preferable that at least one of R ³ , R ⁴ , R ⁵ and R ⁶ is an alkoxyl group or an aryloxy group. This alkoxyl group and aryloxy group are synonymous with the above-mentioned alkoxyl group and aryloxy group, and preferred examples are also the same. In addition, as a substitution position, R ⁴ is particularly preferably an alkoxy group or an aryloxy group.

In addition, at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ⁻ , but R ⁵ is particularly preferably —N ₂ ⁺ X ⁻ .

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

Further, as the diazo compound represented by the general formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ have a diazonioaryl group as a substituent, It may have a diazonio group.
The diazo compound in the present invention can be obtained by a synthesis method described later.

  Specific examples of the diazo compound in the present invention (exemplary compounds: A-1 to A-30) are shown below, but the present invention is not limited thereto.

-Synthesis method of diazo compounds-
In the synthesis method of the diazo compound in the present invention, a compound represented by the following general formula (4) can be used as a raw material.

In General Formula (4), R ¹ represents a hydrogen atom, an alkyl group, or an aryl group. R ² represents an alkyl group or an aryl group. R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represents —NHR ¹¹ . R ¹¹ represents a hydrogen atom or an acyl group.

In the general formula (4), an alkyl group or an aryl group represented by R ¹ and R ² has the same meaning as R ¹ and R ² in the general formula (1) represents an alkyl group or an aryl group, the The preferable example is also the same.

Examples of the monovalent substituent in R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (4) include an alkyl group, an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, and an acylamino group. , An alkoxycarbonyl group, a carbamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group are preferred, and further a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group A sulfonylamino group or NHR ¹¹ is preferable, but as described above, at least one of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represents —NHR ¹¹ .

R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (4) are an alkyl group, aryl group, halogen atom, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, alkoxycarbonyl group, carbamoyl group , A cyano group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group, these are the same as those in the general formula (1), and preferred examples thereof are also the same.

In the general formula (4), at least one of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represents —NHR ¹¹ , and R ⁷ represents a hydrogen atom or an acyl group.
The acyl group represented by R ¹¹ is preferably an acyl group having 1 to 30 carbon atoms, and more preferably an acyl group having 1 to 20 carbon atoms. Specifically, for example, formyl group, acetyl group, propionyl group, pivaloyl group, butyroyl group, 4-phenoxybutyroyl group, benzoyl group, (4-ethoxyphenyl) carbonyl group, (2-butoxyphenyl) carbonyl group, A (4-chlorophenyl) carbonyl group is preferred, and a formyl group, acetyl group, propionyl group, pivaloyl group, benzoyl group, and (4-chlorophenyl) carbonyl group are particularly preferred.
When any of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (4) is an amino group, it may form a salt with an acid. Preferred acids include hydrochloric acid, sulfuric acid, methanesulfonic acid, and toluenesulfonic acid.

In the synthesis of the diazo compound in the present invention, when R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (4) are —NHR ⁷ (R ⁷ = acyl group), this is converted to —NHR ¹¹ (R ¹¹ = Hydrogen atom). This conversion can be performed under acidic conditions or basic conditions, and the acid to be added is preferably hydrochloric acid, sulfuric acid, alkylsulfonic acid, or arylsulfonic acid, and the base to be added is sodium hydroxide, potassium hydroxide, Calcium hydroxide is preferred. Compounds that generate an acid upon addition are also preferred, and acetyl chloride and propionyl chloride are preferred.
As the reaction solvent, water, methanol, ethanol, propanol, butanol, and acetic acid are preferable, and a mixed solvent thereof is also preferable.
The reaction temperature is preferably between room temperature and the boiling point of the solvent, but it is preferably carried out at a high temperature of 50 ° C. or higher from the viewpoint of reaction rate and solubility.
When R ⁷ , R ⁸ , R ⁹ and R ¹⁰ in the general formula (4) are —NHR ¹¹ (R ¹¹ = hydrogen atom), this compound is treated with sodium nitrite, potassium nitrite, nitrosyl sulfate in an acidic solvent. The diazo compound in the present invention can be obtained by diazotization using isoamyl nitrite or the like.

<< Method for Synthesizing Compound Represented by Formula (4) >>
The compound represented by the general formula (4) can be synthesized by using a compound represented by the following general formula (5).

In General Formula (5), R ¹ represents a hydrogen atom, an alkyl group, or an aryl group. R ² represents an alkyl group or an aryl group. R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a monovalent substituent. However, at least one of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represents —NHR ¹¹ . R ¹¹ represents a hydrogen atom or an acyl group.

R ¹ , R ² , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ in the general formula (5) are R ¹ , R ² , R ⁷ , R ⁸ , R ⁹ , has the same meaning as R ¹⁰ and R ^11, preferred examples are also the same.

In the method for synthesizing the compound represented by the general formula (5), the following conditions can be used.
The synthesis reaction is an oxidation reaction. As the oxidizing agent, chlorine, bromine, iodine, sulfonyl chloride, or sulfuryl chloride is preferable, and bromine is most preferable from the viewpoint of handling and yield.
The amount of the oxidizing agent used is preferably 90% to 130%, particularly preferably 100% to 110%, in terms of molar ratio, relative to the compound represented by the general formula (5). If the amount of the oxidizing agent is small, the raw material remains, and if it is large, the side reaction product may increase.

  The solvent used in the reaction is not particularly limited as long as it does not react with an oxidizing agent, and acetic acid, propionic acid, acetonitrile, chloroform, methylene chloride, ethyl acetate, and chlorobenzene are preferable. In particular, acetic acid, chloroform, and methylene chloride are preferable from the viewpoint of yield. A mixed solvent of these solvents can also be used. The amount of the solvent used may be such that the raw material dissolves. However, if the concentration is high, the viscosity increases and the stirring efficiency decreases, and if the concentration is low, the volume efficiency decreases. Therefore, the compound represented by the general formula (4) to be used The range of 100% to 2000% is preferable with respect to the mass of. More preferably, it is 200% to 500%.

  What is necessary is just to select reaction temperature in the range of -10 degreeC-120 degreeC. In general, the reaction is completed faster as the temperature is higher. However, since this synthesis method reacts quickly even at room temperature or lower, it is preferably carried out in the range of -5 ° C to 35 ° C from the viewpoint of yield. When acetic acid is used as a solvent, it is preferably carried out at 10 ° C. or higher in order to prevent crystallization of acetic acid.

  Synthesis of the compound represented by the general formula (4) is described in “Organic Functional Group Preparations Volume II” (Stanley R. Sandler, Wolf Karo (1971) Academic Press, Inc.), “New Experimental Chemistry Course 14”. Synthesis and Reaction III "((1976) Maruzen Co., Ltd.), J. MoI. Chem. Soc. (C) (1967) 2212-2220 and the like.

  In addition, the diazo compound in the present invention may be either an oily substance or a crystalline state, but is preferably in a crystalline state at normal temperature from the viewpoint of handleability. These diazo compounds in the present invention may be used alone or in combination of two or more, or may be used in combination with existing diazo compounds.

The content of the heat-sensitive recording layer of the diazo compound in the present invention is preferably from 0.02 to 5 g / m ^2, is 0.1-4 g / m ² from the viewpoint of developed color density more preferred.

  In order to stabilize the diazo compound in the present invention, a complex compound can be formed using zinc chloride, cadmium chloride, tin chloride or the like to stabilize the diazonium salt.

  The diazo compound represented by the general formula (1) develops color by reaction with a coupler to be described later, and a high color density is obtained. On the other hand, the diazo compound is excellent in photodegradability in a wavelength range of 380 to 460 nm such as a fluorescent lamp. Since it has a high-speed decomposability that can be sufficiently fixed even with light irradiation for a long time, it is very useful as a color developing component used in a photo-fixing type thermal recording material.

(coupler)
Next, a coupler (coupling component) that can be used in the heat-sensitive recording material of the present invention will be described.
As the coupler, any compound can be used as long as it forms a dye by coupling with a diazo compound in a basic atmosphere and / or a neutral atmosphere. All so-called 4-equivalent couplers for silver halide photographic materials can be used as couplers. These can be selected according to the target hue.
For example, there are so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives, and the like. Specific examples 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, 2-hydroxy- Sodium 3-naphthalenesulfonate, 2-hydroxy-3-naphthalenesulfonic acid anilide, 2-hydroxy-3-naphthalenesulfonic acid morpholinopropylamide, 2-hydroxy-3-naphthalenesulfonic acid-2-ethylhexyloxypropylamide, 2- Hydroxy-3-naphthalenesulfonic acid-2-ethylhexylamide, 5-acetamido-1-naphthol, 1-hydroxy-8-acetamidonaphthalene-3,6-disulfonic acid sodium salt, 1-hydroxy-8-acetate Midonaphthalene-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-methoxy Carbonyl-1,3-cyclohexanedione, 5- (2,5-di-n-octyloxyphenyl) -1,3-cyclohexanedione,

N, N′-dicyclohexylbarbituric acid, N, N′-di-n-dodecylbarbituric acid, Nn-octyl-N′-n-otatadecylbarbituric acid, N-phenyl-N ′-( 2,5-di-n-octyloxydiphenyl) barbituric acid, N, N′-bis (octadecyloxycarbonylmethyl) barbituric acid, 1-phenyl-3-methyl-5-pyrazolone, 1- (2,4 , 6-trichlorophenyl) -3-anilino-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-benzamido-5-pyrazolone, 6-hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) -2-pyridone, 2,4-bis- (benzoylacetamido) toluene, 1,3-bis- (pivaloylacetamidomethyl) benzene, benzo 1- (2-ethylhexyloxy) Propyl) -3-cyano-4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (dodecyloxypropyl) -3-acetyl-4-methyl-6-hydroxy-1,2-dihydropyridine 2-one, 1- (4-n-octyloxyphenyl) -3-tert-butyl-5-aminopyrazole and the like.

  The details of the coupler are described in JP-A-4-201483, JP-A-7-223367, JP-A-7-223368, JP-A-7-323660, Japanese Patent Application No. 5-278608, 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. 8-027095, Japanese Patent Application No. No. 8-027096, Japanese Patent Application No. 8-030799, Japanese Patent Application No. 8-12610, Japanese Patent Application No. 8-132394, Japanese Patent Application No. 8-358755, Japanese Patent Application No. No. 8-358756, Japanese Patent Application No. 9-069990, and the like.

Among the above, the coupler in the present invention is particularly preferably a compound represented by the following general formula (3) or a tautomer thereof.

In the general formula (3), E ¹ and E ² each independently represents an electron-withdrawing group. E ¹ and E ² may be bonded to each other to form a ring.

The electron-withdrawing group represented by E ¹ and E ² means a substituent having a positive Hammett σ _p value, which may be the same or different. For example, an acetyl group, Propionyl group, pivaloyl group, chloroacetyl group, trichloroacetyl group, trifluoroacetyl group, 1-methylcyclopropylcarbonyl group, 1-ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl Group, acyl group such as thenoyl group; oxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group, 2-methoxyethoxycarbonyl group, 4-methoxyphenoxycarbonyl group; carbamoyl group, N, N-dimethylcarbamoyl group, N, N -Diethylcarbamoyl group, N-phenylcarbamoy Groups, carbamoyl groups such as N- [2,4-bis (pentyloxy) phenyl] carbamoyl group, N- [2,4-bis (octyloxy) phenyl] carbamoyl group, morpholinocarbonyl group; methanesulfonyl group, benzenesulfonyl Group, alkylsulfonyl group such as toluenesulfonyl group or arylsulfonyl group; phosphono group such as diethylphosphono group; benzoxazol-2-yl group, benzothiazol-2-yl group, 3,4-dihydroquinazolin-4-one Preferred examples include a heterocyclic group such as a 2-yl group and a 3,4-dihydroquinazoline-4-sulfon-2-yl group; a heterocyclic group; a nitro group; an imino group; and a cyano group.

Further, the electron withdrawing groups represented by E ¹ and E ² may be bonded to form a ring. The ring formed by E ¹ and E ² is preferably a 5- to 6-membered carbocyclic or heterocyclic ring.

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

  The tautomers of the above couplers are those that exist as isomers of the couplers typified above, and have a relationship in which the structure easily changes between the two. The coupler used in the present invention As such, the tautomer is also preferable.

The content of the heat-sensitive recording layer of the coupler is preferably 0.02~10g / m ^2, is 0.1~6.0g / m ² from the viewpoint of developed color density more preferred.

(Microcapsule)
The microcapsule in the present invention is obtained by polymerizing a compound having active hydrogen and an isocyanate compound to form a microcapsule wall, and the isocyanate compound is represented by at least a polyfunctional isocyanate compound and the following general formula (2). A reaction product with a polyether derivative having a terminal amino group is used.

  The isocyanate compound used for the production of the microcapsules in the present invention contains at least a reaction product of (1) a polyfunctional isocyanate compound and (2) a polyether derivative represented by the following general formula (2) as described above. In addition, other known isocyanate compounds and various known additives can be contained as required or necessary. The microcapsule of the present invention having a polyurea or polyurethane wall formed by polymerization of such an isocyanate compound and an active hydrogen compound has a high heat sensitivity, and the microcapsule encapsulating the coloring component is a coupler or developer. It exhibits high color developability when in contact with and has excellent properties for shelf life.

  More specifically, the isocyanate compound used according to the present invention comprises (1) an aliphatic, cycloaliphatic and / or aromatic polyfunctional isocyanate compound having at least two, preferably three or more functional groups. Reaction preferably obtained by reacting an aliphatic and / or cycloaliphatic polyfunctional isocyanate compound with (2) a polyether derivative having an amino group at the terminal represented by the following general formula (2) Product.

  However, in the present invention, when forming a microcapsule, a reaction product of the polyfunctional isocyanate compound and an ether derivative having an amino group at the terminal represented by the general formula (2) is directly added. Alternatively, each of them may be added to either the oil phase or the aqueous phase to form the reaction product in the polymerization reaction of the microcapsule wall. The polyfunctional isocyanate compound and the ether derivative having an amino group at the terminal represented by the following general formula (2) may be added to either the aqueous phase or the oil phase. It is preferable to add to the oil phase and add an ether derivative having an amino group at the terminal represented by the general formula (2) described later to the aqueous phase.

-Polyfunctional isocyanate compound-
Specific examples of the polyfunctional isocyanate compound that can be used in the above reaction include, for example, compounds having two isocyanate groups in the molecule such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2 , 4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxy-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene -1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-diphenylpropane diisocyanate, , 4'-diphenylhexafluoropropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3- Diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane and 1,3-bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate, etc. Can be mentioned. Further, addition reaction products of these bifunctional isocyanate compounds with bifunctional alcohols such as ethylene glycols and bisphenols and phenols can also be used.

  Examples of other polyfunctional isocyanate compounds other than the above are the above-mentioned bifunctional isocyanate compounds as main raw materials, addition of these trimers (burette or isocyanurate), polyols such as trimethylolpropane, and bifunctional isocyanate compounds. A polyfunctional compound, a formalin condensate of benzene isocyanate, a polymer of an isocyanate compound having a polymerizable group such as methacryloyloxyethyl isocyanate, lysine triisocyanate, and the like can also be used. In particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are used as main raw materials, and in addition to these trimers (burette or isosinurate), it is polyfunctional as an adduct with trimethylolpropane. These are preferred. These compounds are described in “Polyurethane Resin Handbook” (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun, 1987).

  Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene- Adducts with 1,3-diisocyanate are preferred, in particular xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate. Adducts are preferred.

In the present invention, the reaction ratio between the polyether derivative having an amino group at the terminal represented by the following general formula (2) and the polyfunctional isocyanate compound is 1/100 to 50/100 (mol ratio). 2/100 to 40/100 are particularly preferable. When the molar reaction ratio is less than 1/100, the effect of improving the sensitivity may be insufficient. When the molar reaction ratio exceeds 50/100, the remaining amount of isocyanate groups is too small to form capsules. May be difficult.
For example, the addition reaction of a polyether derivative having an amino group at the terminal represented by the general formula (2) and a polyfunctional isocyanate may be carried out while stirring both compounds in an organic solvent not having active hydrogen. It can be obtained by room temperature or heating (about 20 to 80 ° C.). Examples of the organic solvent include ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like.
In addition, as an isocyanate compound used by this invention, the addition reaction product of the polyether derivative which has an amino group at the terminal represented by this General formula (2), and a polyfunctional isocyanate compound is used individually by 1 type. Or you may use a 2 or more types of mixture.

  As the isocyanate compound used in the present invention, as a raw material of the microcapsule, in addition to the addition reaction product of a polyether derivative having an amino group at the terminal and a polyfunctional isocyanate represented by the following general formula (2), A known polyfunctional isocyanate having two or more isocyanate groups can be used in combination. As examples of such known polyfunctional isocyanates, the compounds exemplified as the aforementioned polyfunctional isocyanate can be used in combination at an appropriate ratio.

  These known polyfunctional isocyanate compounds used in combination may be used alone or in combination of two or more. However, when used in combination, the mass ratio of the polyether derivative having an amino group at the terminal represented by the following general formula (2) and the known polyfunctional isocyanate used in combination with the reaction product of the polyfunctional isocyanate is 100/0. The range of ˜5 / 95 is preferable, and the range of 90/10 to 10/90 is more preferable.

  The polymerization of the isocyanate compound in the present invention with a compound having active hydrogen is performed, for example, by a reaction with a compound having two or more active hydrogen atoms in the molecule. Examples of such compounds having active hydrogen include water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyhydric amine compounds such as ethylenediamine and diethylenetriamine, and mixtures thereof. . Among these, it is preferable to perform polymerization using water. As a result, polyurea and / or polyurea walls are formed.

  The polyether derivative having a terminal amino group represented by the general formula (2) in the present invention (hereinafter sometimes referred to as “polyether derivative according to the present invention”) will be described.

In general formula (2), X represents a single bond, —CO— or —SO ₂ —. A represents an aryl group or an alkyl group. m represents 2 or 3. L represents an alkylene group. R represents an alkyl group, an aryl group, or an acyl group. n represents 10-500.

  Since the polyether derivative represented by the general formula (2) is easy to synthesize, it is possible to easily produce the isocyanate compound and the microcapsule using the polyether derivative as a raw material. In addition, the heat-sensitive recording material using the microcapsules of the present invention obtained using the polyether derivative represented by the general formula (2) as a raw material can achieve both high sensitivity and low fog.

In the general formula (2), the aryl group represented by A has 2 or 3 NH ₂ groups as substituents, and may further have other substituents, and has a total carbon number of 6 to 30. Of these, 6 to 20 are particularly preferable. Examples of the aryl group represented by A include those represented by the following formula as -A- (NH ₂ ) _m in the general formula (2).

In the above formula, S represents a substituent other than the NH ₂ group of the aryl group represented by A, preferably a halogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a cyano group, particularly A halogen atom, an alkyl group, and an alkoxy group are preferable.

In the general formula (2), the alkyl group represented by A has 2 or 3 NH ₂ groups as substituents, may further have other substituents, and has a branch. The total number of carbon atoms is preferably 1-30, and more preferably 1-20. As the substituent of the alkyl group represented by A, an aryl group, an alkenyl group, an alkoxy group, and an alkoxycarbonyl group are preferable, and an aryl group is particularly preferable. Examples of the alkyl group represented by A include those represented by the following formula as -A- (NH ₂ ) _m in the general formula (2).

As A, an aryl group is preferable.
In general formula (2), m is preferably 2.

  In the general formula (2), the alkylene group represented by L may have a substituent or may have a branch, and preferably has 2 to 20 carbon atoms in particular, 10 is preferred. As the substituent, an aryl group, an alkenyl group, an alkoxy group, and an acyl group are preferable, and an aryl group is particularly preferable. Examples of such an alkylene group include ethylene, propylene, tetramethylene, phenylethylene, cyclohexylene, vinylethylene, phenoxymethylethylene, and the like.

  The repeating unit -L-O- may represent an independent group in n repetitions, but is preferably the same group. Examples of the polyether moiety having such a repeating unit include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, polyethylene oxide-polypropylene oxide-block copolymer, polyethylene oxide-polypropylene oxide random copolymer. A polymer etc. are mentioned.

  In the general formula (2), the alkyl group represented by R may have a substituent or may have a branch, and preferably has 1 to 30 carbon atoms, particularly 1 to 20 carbon atoms. Is preferred. As the substituent, an aryl group, an alkenyl group, and an alkoxy group are preferable. Such alkyl groups include methyl, ethyl, butyl, isopropyl, behenyl, benzyl, allyl, oleyl, methoxyethyl and the like.

  In the general formula (2), the aryl group represented by R may have a substituent, preferably has a total carbon number of 6 to 30, and particularly preferably 6 to 20. As the substituent, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, and an alkoxy group are preferable, and an alkyl group and an alkoxy group are particularly preferable. Such aryl groups include phenyl, nonylphenyl, octylphenyl, fluorophenyl, styrylphenyl, phenylethenylphenyl, methoxyphenyl, and the like.

  In the general formula (2), the acyl group represented by R may be an aliphatic acyl group or an aromatic acyl group, may have a substituent, may have a branch, Those having 2 to 30 carbon atoms are preferred, and 2 to 20 are particularly preferred. As the substituent, an alkyl group, an aryl group, an alkenyl group, and an alkoxy group are preferable. Examples of such acyl groups include acetyl, benzoyl, (meth) acryloyl, oleoyl, lauroyl, stearoyl, methoxybenzoyl and the like.

R is preferably an alkyl group or an acyl group, particularly preferably an alkyl group.
In addition, the polyether derivative represented by General formula (2) is a compound which may be synthesize | combined through the process of reducing a nitro group and producing an amino group so that it may mention later. Therefore, when the polyether derivative represented by the general formula (2) is synthesized through a step of reducing the nitro group to generate an amino group, the substituent for R does not include a nitro group.

  In the general formula (2), n is preferably 10 to 400, and particularly preferably 10 to 300.

  Specific examples (example compounds: 1-1 to 3-5) of the polyether derivative having a terminal amino group represented by the general formula (2) are shown below, but the present invention is limited by the following specific examples. is not.

  The polyether derivative represented by the general formula (2) can be synthesized by a known method. As a synthesis method, J. et al. Org. Chem. 45, 5364 (1980), JP-A-11-263834, Eur. Poly. J. et al. 19, 341 (1983), J. Am. Am. Chem. Soc. 118, 10150 (1996), Tetrahedron Letters 43, 1529 (2002), and the like. For example, when A represents an aryl group, a compound represented by the following general formula (6) is reacted with an aromatic nitro compound represented by the following general formula (7) to obtain a compound of the general formula (8). After being obtained, it can be produced by hydrogen reduction in the presence of a catalytic hydrogen reduction catalyst.

  In the reaction of the compound represented by the general formula (6) and the compound represented by the general formula (7), it is preferable to use a base such as triethylamine, pyridine, DBU or sodium hydride. A solvent may be used for the reaction, and toluene, acetonitrile, tetrahydrofuran, and methylene chloride are preferable as the solvent. The reaction temperature is preferably 0 ° C. to 100 ° C. or the reflux temperature of the solvent used.

  As the catalyst for catalytic hydrogen reduction used for hydrogen reduction of the compound of the general formula (8), a known catalyst can be used. Regarding the catalyst, “4th edition experimental chemistry course 26”, pages 251 to 266 ( Detailed information on the Chemical Society of Japan, Maruzen, 1992). A solvent may also be used, and methanol, ethanol, 2-propanol, tetrahydrofuran, and chloroform are preferable as the solvent. The reaction temperature of the reaction is preferably 0 ° C. to 60 ° C. or the reflux temperature of the solvent used.

(Organic base)
In the heat-sensitive recording material of the present invention, an organic base is preferably added 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. JP-A-46806, JP-A-62-20082, JP-A-57-169745, JP-A-60-94381, JP-A-57-123086, JP-A-60-49991, Preferred examples include those described in JP-B-2-24916, JP-B-2-28479, JP-A-60-165288, and JP-A-57-185430. These may be used alone or in combination of two or more.

  Among 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-bis {[3- (N-methylpiperazino) -2 Piperazines such as -hydroxy] propyloxy) benzene, N- [3- (β-naphthoxy) -2-hydroxy] propylmorpholine, 1,4-bis (3- Morpholines such as morpholino-2-hydroxy-propyloxy) benzene and 1,8-bis (3-morpholino-2-hydroxy-propyloxy) benzene, N- (3-phenoxy-2-hydroxypropyl) piperidine, N- Piperidines such as dodecylpiperidine and guanidines such as triphenylguanidine, tricyclohexylguanidine and dicyclohexylphenylguanidine are preferred.

As the usage-amount of the said organic base, 0.1-30 mass parts is preferable with respect to 1 mass part of diazo compounds.
If the amount used is less than 0.1 parts by mass, a sufficient color density may not be obtained, and if it exceeds 30 parts by mass, decomposition of the diazo compound may be promoted.

(Coloring aid)
In addition to the above organic base, a coloring aid can be added to the heat-sensitive recording layer for the purpose of accelerating the coloring reaction, that is, for rapid and complete thermal printing with low energy. Here, the color assistant is a substance that increases the color density during heat recording or controls the color temperature, and lowers the melting point of couplers, basic substances or diazonium salts, or softens the capsule wall. It is for making it the conditions which a diazonium salt, a basic substance, a coupler, etc. react easily by the effect | action which can reduce this.

  Examples of the coloring aid include phenol derivatives, naphthol derivatives, alkoxy-substituted benzenes, alkoxy-substituted naphthalenes, aromatic ethers, thioethers, esters, amides, ureidos, urethanes, sulfonamide compounds, hydroxy compounds, and the like.

  The coloring aid includes a heat-melting substance. The heat-meltable substance is a substance that is solid at normal temperature and has a melting point of 50 ° C. to 150 ° C. that melts by heating, and is a substance that can dissolve a diazonium salt, a coupler, an organic base, or the like. Specific examples include carboxylic acid amides, N-substituted carboxylic acid amides, ketone compounds, urea compounds, and esters.

(Antioxidant)
In the heat-sensitive recording material of the present invention, for the purpose of improving fastness to light and heat of a thermochromic image or reducing yellowing due to light of an unprinted portion (non-image portion) after fixing, the following is shown. It is also preferable to use a known antioxidant or the like.

  Examples of the antioxidant include, for example, European Patent Publication No. 223739, Publication No. 309401, Publication No. 309402, Publication No. 310551, Publication No. 310552, Publication No. 457416, and German Patent Publication No. 3435443, JP-A-54-48535, JP-A-62-262047, JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262. JP-A-3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. 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, JP-A-60-125471, JP-A-60-125472, and JP-A-60-287485. No. 60-287486, No. 60-287487, No. 60-287488, No. 61-160287, No. 61-185483, No. 61-2111079, No. 62-146678. Gazette, 62-146680 gazette, 62-146679 gazette, 62-282858 gazette, 63-051174 gazette, 63-898877 gazette, 63-88380 gazette, 63-088381 gazette. 63-203372, 63-224989, 63-25128 No. 63-267594, No. 63-182484, JP-A-1-239282, No. 4-29185, No. 4-291684, No. 5-188687, No. 5-188686. And JP-A-5-110490, JP-A-5-170361, JP-B-48-043294, JP-A-48-033212, and the like.

  Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline 6-ethoxy-1-phenyl-2,2.4-trimethyl-1,2,3,4-tetrahydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3 4-tetrahydroquinoline, nickel cyclohexaneate, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2-methyl-4-methoxy-diphenylamine, 1 -Methyl-2-phenylindole and the like.

As addition amount of the said antioxidant or various additives, 0.05-100 mass parts is preferable with respect to 1 mass part of diazonium salts, and 0.2-30 mass parts is more preferable.
The antioxidant and various additives may be contained in a microcapsule together with a diazonium salt, or may be contained as a solid dispersion together with a coupler, a basic substance, and other color forming aids, or emulsified. It may be contained together with a suitable emulsification aid, or may be contained in both forms. Moreover, antioxidant or various additives may be used independently and can also be used together. Furthermore, it can also be contained in the protective layer.

The antioxidant and various additives need not necessarily be added to the same layer.
When multiple combinations of the above antioxidants and / or various additives are used, they are structurally classified as anilines, alkoxybenzenes, binderd phenols, hindered amines, hydroquinone derivatives, phosphorus compounds, sulfur compounds. In addition, different structures may be combined with each other, or a plurality of the same structures may be combined.

(Free radical generator)
For the purpose of reducing yellowing of the background after image recording, a free radical generator (compound that generates free radicals upon light irradiation) used in a photopolymerizable composition or the like can be added.
Examples of the free radical generator include aromatic ketones, quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, acyl oxime esters, and the like.
The amount of the free radical generator added is preferably 0.01 to 5 parts by mass with respect to 1 part by mass of the diazonium salt.

(Vinyl monomer)
Similarly, for the purpose of reducing yellow coloring, a polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as “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 monomer or prepolymer.

Examples of the vinyl monomer include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds, and the like. The vinyl monomer is used in a proportion of 0.2 to 20 parts by mass with respect to 1 part by mass of the diazonium salt.
The free radical generator and the vinyl monomer can 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 and the like can be added as an acid stabilizer.

(Layer structure)
The heat-sensitive recording layer is preferably an embodiment containing an organic base.
Application of the heat-sensitive recording layer can be appropriately selected from known application methods such as bar coating, blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and curtain coating. It is done.
The coating, as a dry coating amount of the heat-sensitive recording layer after drying, 2.5~30g / m ² is preferred.

  The configuration of the thermosensitive recording layer is not particularly limited. For example, the thermosensitive recording layer may be a single layer in which microcapsules, couplers, organic bases and the like are all contained in the same layer, or a separate layer. It may be a multi-layer stacked type as included in the above. Alternatively, an intermediate layer described in Japanese Patent Application No. 59-177669 may be provided on the support, and then a heat-sensitive recording layer may be applied and formed.

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

(binder)
In the heat-sensitive recording material of the present invention, each layer such as a heat-sensitive recording layer, an intermediate layer, or a protective layer described later can contain a binder. Examples of the binder include known water-soluble polymer compounds and latexes. Can be appropriately selected.

  Examples of the water-soluble polymer compound include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivatives, 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, polyacrylic acid, polyacrylic acid amide and the like, and modified products thereof.

Examples of the latex include styrene-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion.
Of these, hydroxyethyl cellulose, starch derivatives, gelatin, polyvinyl alcohol derivatives, polyacrylic acid amide derivatives and the like are preferable.

  The heat-sensitive recording material can also contain a pigment, and examples of the pigment include organic and inorganic materials such as kaolin, calcined kaolin, talc, wax, diatomaceous earth, calcium carbonate. , Aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone, silica, magnesium carbonate, titanium oxide, alumina, barium carbonate, barium sulfate, mica, microballoon, urea-formalin A filler, a polyester particle, a cellulose filler etc. are mentioned.

  In addition, various additives such as known waxes, antistatic agents, antifoaming agents, conductive agents, fluorescent dyes, surfactants, ultraviolet absorbers and their precursors can be used as necessary.

<Protective layer>
In the thermosensitive recording material, a protective layer may be provided on the thermosensitive recording layer as necessary. Two or more protective layers may be laminated as necessary.
Materials used for the protective layer include 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 sulfonic acid soda, alginate soda Water-soluble polymer compounds such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex Latexes such as vinyl acetate emulsion.

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

For the protective layer, known pigments, metal soaps, waxes, surfactants and the like can also be used.
The coating amount of the protective layer is preferably 0.2 to 5 g / m ^{2 and} more preferably 0.5 to ² g / m ^{2 in} terms of dry coating amount. The film thickness is preferably 0.2 to 5 μm, and more preferably 0.5 to 2 μm.

Moreover, when providing a protective layer, you may contain a well-known ultraviolet absorber and its precursor in this protective layer.
The protective layer can be provided by the above-described known coating method as in the case of forming the heat-sensitive recording layer on the support.

<Support>
As the support that can be used for the heat-sensitive recording material, any of the paper supports used for ordinary pressure-sensitive paper, heat-sensitive paper, dry-type and wet-type diazo copy paper, etc. can be used. Acid paper, neutral paper Coated paper, plastic film laminated paper, synthetic paper, and plastic films such as polyethylene terephthalate and polyethylene naphthalate can be used.

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

Further, if necessary, an antihalation layer is provided between the support and the thermosensitive recording layer or on the surface of the support on the side where the thermosensitive recording layer is provided, and a slipping layer or an antistatic layer is provided on the backside surface. An adhesive layer or the like can also be provided.
Also, a label may be formed by combining release paper with an adhesive layer on the back surface of the support (the surface on which the thermosensitive recording layer is not provided).

As described above, by using the diazo compound of the present invention for the heat-sensitive recording layer, a high color density can be obtained and light fixing can be performed at high speed. By increasing the light fixing speed, the recording time can be shortened, and the diazonium salt itself is excellent in its decomposability, so that a sufficient fixing effect can be expected. Therefore, a decrease in whiteness due to coloring of the non-image portion (background portion) can be prevented, and a high-contrast image with little density fluctuation can be obtained. That is, it is possible to achieve both improvement in stability and high speed as a recording material.
Furthermore, the long-term stability as a recording material can be further enhanced by encapsulating the diazonium salt in a microcapsule.

<Image forming method>
Image formation using a heat-sensitive recording material may be performed by the following method.
That is, for example, the surface of the heat-sensitive recording material on which the heat-sensitive recording layer is provided is image-wise heated and printed by a heating device such as a thermal head, so that the polyurea and / or Alternatively, the capsule wall containing polyurethane becomes soft and becomes permeable to substances, and when a coupler or a basic substance (organic base) outside the capsule enters into the microcapsule, the image is colored and image formation is performed. Also good. In this case, after color development, by further irradiating light corresponding to the absorption wavelength of the diazonium salt (photofixing), the diazonium salt undergoes a decomposition reaction and loses the reactivity with the coupler, thereby fixing the image. . By performing photofixing as described above, the unreacted diazonium salt loses its activity by causing a decomposition reaction. Therefore, the density of the formed image changes, and coloring due to the occurrence of stain in the non-image area (background area) That is, a decrease in whiteness and a decrease in image contrast accompanying the decrease can be suppressed.

Examples of light sources used for photofixing include various fluorescent lamps, xenon lamps, mercury lamps, etc., and it is highly efficient that the emission spectrum of these light sources substantially matches the absorption spectrum of the diazonium salt in the thermal recording material. It is preferable in that it can be fixed.
In particular, in the present invention, it is particularly preferable to use a light source having a light emission center wavelength of 380 to 460 nm.

  Further, it can also be used as a light-writing heat-developable heat-sensitive recording material in which image-like writing is performed with light and heat development is performed to form an image. In this case, the printing process is performed by a light source such as a laser instead of the heating device as described above.

In the thermosensitive recording material, a multicolor thermosensitive recording material can be constituted by laminating a plurality of thermosensitive recording layers having different color hues. Examples of the heat-sensitive recording layer to be laminated include a heat-sensitive recording layer containing a photodegradable diazonium salt.
Regarding the above-mentioned multicolor heat-sensitive recording materials, JP-A-3-288688, JP-A-4-135787, JP-A-4-144784, JP-A-4-144785, JP-A-4-194842, JP-A-247447. No. 4-247448, No. 4-340540, No. 4-340541, No. 5-34860, No. 5-194842, No. 7-316280, etc. is there.

  For example, the layer configuration of the full color thermosensitive recording material may be configured in the following manner. However, the present invention is not limited to this. That is, two diazonium salts having different photosensitive wavelengths are combined with couplers that can react with each diazonium salt when heated to develop different hues, and are contained in separate layers. It may be a full-color heat-sensitive recording material in which a heat-sensitive recording layer (B layer, C layer) and a heat-sensitive recording layer (A layer) obtained by combining an electron-donating colorless dye and an electron-accepting compound are laminated, Alternatively, the two thermosensitive recording layers (B layer and C layer), a diazonium salt having a different photosensitive wavelength, and a coupler that develops color by reacting with the diazonium salt when heated (A) A full-color heat-sensitive recording material laminated with a layer).

  Specifically, from the support side, a first dye containing 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 that develops color by reacting with the diazonium salt when heated. A heat-sensitive recording layer (A layer), a diazonium salt having a maximum absorption wavelength of 360 nm ± 20 nm, and a second heat-sensitive recording layer (B layer) containing a coupler that reacts with the diazonium salt when heated to develop a color, and a maximum absorption wavelength. A third heat-sensitive recording layer (C layer) containing a diazonium salt having a thickness of 400 ± 20 nm and a coupler that develops color by reacting with the diazonium salt when heated may be sequentially laminated.

In this case, full-color image recording can be performed by selecting the color development hue of each heat-sensitive recording layer 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 laminated in any way. However, in terms of color reproducibility, yellow, cyan, magenta, or yellow, magenta are used from the support side. It is preferable to laminate in the order of cyan.

As a recording method in the case of a multicolor thermosensitive recording material, for example, it can be performed as follows.
First, the third heat-sensitive recording layer (C layer) is heated to develop the color of the diazonium salt and coupler contained in the layer. Next, the light of 400 ± 20 nm is irradiated to decompose the unreacted diazonium salt contained in the C layer. Next, sufficient heat is applied to the second heat-sensitive recording layer (B layer) to develop color, and the diazonium salt and coupler contained in the layer are colored. At this time, the C layer is also strongly heated at the same time, but the diazonium salt has already decomposed and the color developing ability is lost, so no color is developed. Thereafter, the light of 360 ± 20 nm is irradiated to decompose the diazonium salt contained in the B layer. Finally, the first heat-sensitive recording layer (A layer) is colored by applying sufficient heat. At this time, the C layer and the B layer are also strongly heated at the same time, but since the diazonium salt has already been decomposed and the coloring ability is lost, no color is developed.

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

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

When the heat-sensitive recording material of the present invention is a multicolor 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 as an upper layer if necessary, or It is desirable to provide 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 that functions as a precursor of an ultraviolet absorber is used in the light transmittance adjustment layer, it does not function as an ultraviolet absorber before irradiating light in a wavelength region necessary for fixing, so that a high light transmittance is obtained. Therefore, when fixing the light-fixing type thermosensitive recording layer, the wavelength of the region necessary for fixing can be sufficiently transmitted, and the visible light transmittance is also high, which may hinder the fixing of the thermosensitive recording layer. Absent.

  On the other hand, the precursor of the ultraviolet absorber is irradiated with light in a wavelength region necessary for photofixing (photodecomposition of a diazonium salt by light irradiation) of the photofixing type thermosensitive recording layer, and then reacts with the light to absorb ultraviolet rays. To function as an agent. This ultraviolet absorber absorbs most of the light having a wavelength in the ultraviolet region and lowers its transmittance, thereby making it possible to improve the light resistance of the heat-sensitive recording material. However, since there is no visible light absorptivity, the visible light transmittance is not substantially changed.

  The light transmittance adjusting layer can be provided in at least one layer in the heat-sensitive recording material, and in particular, it is preferably formed 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 be used in combination.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In the following description, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.

<Preparation of aqueous solution of phthalated gelatin>
Phthalated gelatin (trade name; # 801 gelatin, manufactured by Nitta Gelatin Co., Ltd.) 32 parts, 1,2-benzothiazolin-3-one (3.5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd.) 0 9143 parts and 367.1 parts ion-exchanged water were mixed and dissolved at 40 ° C. to obtain a phthalated gelatin aqueous solution.

<Preparation of alkali-treated gelatin aqueous solution>
25.5 parts of alkali-treated low ion gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industry Co., Ltd.) ) 0.7286 parts, calcium hydroxide 0.153 parts, and ion-exchanged water 143.6 parts were mixed and dissolved at 50 ° C. to obtain an alkali-treated gelatin aqueous solution.

<Synthesis of isocyanate compound>
[Synthesis Example 1]
10 parts of the specific compound example 1-1 of the polyether derivative according to the present invention (polyether derivative having a terminal amino group represented by the general formula (2)) is used at an external temperature of 80 ° C. for 2 hours using a vacuum pump. After drying, the temperature was returned to room temperature, 11 parts of dry ethyl acetate and 1.03 part of xylylene-1,3-diisocyanate were added under a nitrogen stream, and the mixture was stirred at 50 ° C. for 3 hours to obtain an isocyanate compound ( A solution (50% by mass) of 1) was obtained.

[Synthesis Example 2]
A solution (50 mass%) of the isocyanate compound (2) was obtained in the same manner as in Synthesis Example 1 except that the compound of Specific Compound Example 1-1 in Synthesis Example 1 was changed to the compound of Specific Compound Example 1-2. .

[Synthesis Example 3]
A solution (50 mass%) of the isocyanate compound (3) was obtained in the same manner as in Synthesis Example 1 except that the compound of Specific Compound Example 1-1 in Synthesis Example 1 was changed to the compound of Specific Compound Example 1-3. .

<Preparation of yellow thermosensitive recording layer solution>
(Preparation of diazonium salt compound-encapsulating microcapsule solution (a))
To 16.1 parts of ethyl acetate, 4.4 parts of the exemplified compound A-1 (diazo compound represented by the general formula (1)), 4.8 parts of monoisopropylbiphenyl, 4.8 parts of diphenyl phthalate, and diphenyl- 0.4 part of (2,4,6-trimethylbenzoyl) phosphine oxide (trade name: Lucillin TPO, manufactured by BASF Japan Ltd.) was added and heated to 40 ° C. to dissolve uniformly. Mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material (trade name; Takenate D119N (50% ethyl acetate solution), Mitsui Takeda Chemical Co., Ltd.) )) 7.3 parts and 1.3 parts of the above-mentioned isocyanate compound (1) solution were added and stirred uniformly to obtain a mixed liquid (I).

Separately, 16.3 parts of ion-exchanged water and 0.34 part of Scraph AG-8 (50%; manufactured by Nippon Seika Co., Ltd.) are added to 58.6 parts of the above phthalated gelatin aqueous solution, and the mixture (II) is added. Obtained.
The mixed solution (I) was added to the mixed solution (II), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho). After adding 20 parts of water to the obtained emulsion and homogenizing it, the mixture was stirred at 40 ° C. to carry out an encapsulation reaction for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corp.) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content concentration of the capsule liquid was 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (a). The obtained microcapsules had a median diameter of 0.40 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.).

(Preparation of coupler compound emulsion (a))
33.0 parts of ethyl acetate, 9.9 parts of the following coupler compound (C), 9.9 parts of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.), 4,4 ′-(m-phenylenediisopropylidene) diphenol (Brand name; bisphenol M (made by Mitsui Petrochemical Co., Ltd.)) 20.8 parts, 3,3,3 ′, 3′-tetramethyl-5,5 ′, 6,6′-tetra (1-propyloxy) -1,1'-spirobisindane 3.3 parts, 4- (2-ethylhexyloxy) benzenesulfonic acid amide (manac) 13.6 parts, 4-n-pentyloxybenzenesulfonic acid amide (Manac 6.8 parts) and calcium dodecylbenzenesulfonate (trade name: Pionein A-41-C, 70% methanol solution, Takemoto Yushi Co., Ltd.) 4.2 parts are dissolved and mixed. (III) It was.

Separately, 107.3 parts of ion-exchanged water was mixed with 206.3 parts of the above alkali-treated gelatin aqueous solution to obtain a mixed liquid (IV).
The mixed solution (III) was added to the mixed solution (IV), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The obtained coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration was 26.5%. The particle size of the obtained coupler compound emulsion was 0.21 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).
Further, 9 parts of SBR latex (trade name: SN-307, 48% solution, manufactured by Sumika Aves Latex Co., Ltd.) adjusted to 26.5% are added to 100 parts of the above coupler compound emulsion. The mixture was stirred uniformly to obtain a coupler compound emulsion (a).

(Preparation of coating solution (a))
The diazonium salt compound-encapsulated microcapsule liquid (a) and the coupler compound-emulsified liquid (a) are mixed so that the mass ratio of the encapsulated coupler compound / diazo compound is 2.2 / 1, and thermal recording is performed. A layer coating solution (a) was obtained.

<Preparation of magenta thermosensitive recording layer solution>
(Preparation of diazonium salt compound-encapsulating microcapsule solution (b))
In 15.1 parts of ethyl acetate, 2.8 parts of the following diazonium compound (D) (maximum absorption wavelength 365 nm), 4.5 parts of diphenyl phthalate, 4.5 parts of phenyl 2-benzoyloxybenzoate and the following ester compound (E 2.9 (trade name; Light Ester TMP, manufactured by Kyoei Yushi Chemical Co., Ltd.) 2.9 parts and calcium dodecylbenzenesulfonate (trade name: Pionein A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) 1 part was added and heated to dissolve uniformly. Mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct (trade name; Takenate D119N (50% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) ) 2.5 parts and 6.8 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) are added and stirred uniformly. A liquid (V) was obtained.

Separately, 21.0 parts of ion-exchanged water was added to and mixed with 55.3 parts of the above phthalated gelatin aqueous solution to obtain a mixed liquid (VI).
The mixed solution (V) was added to the mixed solution (VI), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). After adding 24 parts of water to the obtained emulsion and homogenizing it, the mixture was stirred at 40 ° C. for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corp.) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content of the capsule liquid was 20.0%, whereby a diazonium salt compound-encapsulating microcapsule liquid (b) was obtained. The obtained microcapsules had a median diameter of 0.44 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.).

(Preparation of coupler compound emulsion (b))
36.9 parts of ethyl acetate, 11.9 parts of the following coupler compound (F), 14.0 parts of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.), 4,4 ′-(m-phenylenediisopropylidene) diphenol ( Product name: Bisphenol M (Mitsui Petrochemical Co., Ltd.) 18.0 parts, 1,1- (p-hydroxyphenyl) -2-ethylhexane 10 parts, 3,3,3 ′, 3′-tetramethyl -5,5 ', 6,6'-tetra (1-propyloxy) -1,1'-spirobisindane 3.5 parts, 3.5 parts of the following compound (G), tricresyl phosphate 1.7 parts, malein 0.8 parts of diethyl acid and 4.5 parts of calcium dodecylbenzenesulfonate (trade name: Piionin A-41-C, 70% methanol solution, Takemoto Yushi Co., Ltd.) were dissolved to obtain a mixture (VII). .

Separately, 107.3 parts of ion-exchanged water was mixed with 206.3 parts of an alkali-treated gelatin aqueous solution to obtain a mixed liquid (VIII).
The mixed solution (VII) was added to the mixed solution (VIII), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The resulting coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration was 24.5% to obtain a coupler compound emulsion (b). The obtained coupler compound emulsion had a median diameter of 0.23 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.).

(Preparation of coating solution (b))
The diazonium salt compound-encapsulated microcapsule liquid (b) and the coupler compound-emulsified liquid (b) were mixed so that the mass ratio of the encapsulated coupler compound / diazo compound was 3.5 / 1. Further, an aqueous solution (5%) of polystyrene sulfonic acid (partially potassium hydroxide neutralized) was mixed so as to be 0.2 parts with respect to 10 parts of the capsule liquid, and the coating liquid for thermal recording layer (b) was prepared. Obtained.

<Preparation of cyan thermosensitive recording layer solution>
(Preparation of electron-donating dye precursor-encapsulated microcapsule solution (c))
To 18.1 parts of ethyl acetate, 7.6 parts of the following electron donating dye (H), 8.0 parts of diisopropylbiphenyl, and 8.0 parts of the following compound (I) (trade name: Irgaperm 2140, manufactured by Ciba Geigy Co., Ltd.) are added. And heated to dissolve uniformly. 7.2 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) as a capsule wall material and polymethylene polyphenyl polyisocyanate (Product name: Millionate MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 5.3 parts thereof were added and stirred uniformly to obtain a mixed liquid (IX).

Separately, 28.8 parts of the above phthalated gelatin aqueous solution, 9.5 parts of ion-exchanged water, 0.17 part of Scraph AG-8 (50%; manufactured by Nippon Seika Co., Ltd.) and sodium dodecylbenzenesulfonate (10% aqueous solution) ) 4.3 parts were added and mixed to obtain a mixed solution (X).
The mixed solution (IX) was added to the mixed solution (X), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 50 parts of water and 0.12 part of tetraethylenepentamine are added to the obtained emulsion to homogenize, and the mixture is stirred at 65 ° C. for 3 hours while removing ethyl acetate. The microcapsule solution was obtained by adjusting the concentration so that the concentration became%. The obtained microcapsules had a median diameter of 1.00 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.).
Further, with respect to 100 parts of the above microcapsule solution, 3.7 parts of sodium dodecylbenzenesulfonate 25% aqueous solution (trade name; Neoperex F-25, manufactured by Kao Corporation) and 4,4′-bistriazinylaminostilbene Fluorescent whitening agent (trade name: Kaycoll BXNL, manufactured by Nippon Soda Co., Ltd.) containing -2,2'-disulfone derivative was added and stirred uniformly to obtain a microcapsule dispersion (c) Got.

(Preparation of electron-accepting compound dispersion (c))
11.3 parts of the above phthalated gelatin aqueous solution and 30.1 parts of ion-exchanged water, 15 parts of 4,4 ′-(p-phenylenediisopropylidene) diphenol (trade name; bisphenol P, manufactured by Mitsui Petrochemical Co., Ltd.) 3.8 parts of 2% -2-ethylhexyl sodium succinate aqueous solution was added and dispersed overnight with a ball mill to obtain a dispersion. The solid content concentration of this dispersion was 26.6%.
After adding 45.2 parts of the alkali-treated gelatin aqueous solution to 100 parts of the dispersion and stirring for 30 minutes, ion-exchanged water was added so that the solids concentration of the dispersion was 23.5% to obtain an electron-accepting compound. A dispersion (c) was obtained.

(Preparation of coating solution (c))
The electron-donating dye precursor-encapsulated microcapsule liquid (c) and the electron-accepting compound dispersion liquid (c) are mixed so that the mass ratio of the electron-accepting compound / electron-donating dye precursor is 10/1. As a result, a coating solution (c) was obtained.

<Preparation of coating solution for intermediate layer>
100.0 parts of alkali-treated low ion gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industry Co., Ltd.) )) 2.857 parts, 0.5 parts of calcium hydroxide and 521.643 parts of ion-exchanged water were mixed and dissolved at 50 ° C. to obtain a gelatin aqueous solution for preparing an intermediate layer.

  10.0 parts gelatin aqueous solution for preparing the intermediate layer, 0.05 parts sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution), boric acid (4. 0 part aqueous solution) 1.5 parts, polystyrenesulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) 0.19 part, 4% aqueous solution of the following compound (J) (manufactured by Wako Pure Chemical Industries, Ltd.) 3.42 parts, 1.13 parts of a 4% aqueous solution of the following compound (J ′) (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.67 parts of ion-exchanged water were mixed to obtain an intermediate layer coating solution.

<Preparation of coating solution for adjusting light transmittance>
(Preparation of UV absorber precursor microcapsule solution)
14.5 parts of [2-allyl-6- (2H-benzotriazol-2-yl) -4-t-octylphenyl] benzenesulfonate as an ultraviolet absorber precursor in 71 parts of ethyl acetate, 2,2′-t -5.0 parts of octyl hydroquinone, 3.0 parts of tricresyl phosphate, 4.6 parts of α-methylstyrene dimer (trade name: MSD-100, manufactured by Mitsui Chemicals, Inc.), calcium dodecylbenzenesulfonate (trade name: Pionine A) 0.45 part of -41-C (70% methanol solution), Takemoto Yushi Co., Ltd.) was dissolved and dissolved uniformly. Add 54.7 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name: Takenate D110N (75% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) as a capsule wall material to the above mixture and stir uniformly. An ultraviolet absorber precursor mixture was obtained.

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

  The UV absorber precursor mixed solution was added to 516.06 parts of the PVA aqueous solution for the UV absorber precursor microcapsule solution, and the mixture was emulsified and dispersed at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). . After adding 254.1 parts of ion-exchanged water to the obtained emulsion and homogenizing it, an encapsulation reaction was carried out for 3 hours with stirring at 40 ° C. Thereafter, 94.3 parts of ion exchange resin Amberlite MB-3 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid concentration of the capsule liquid was 13.5%. The obtained microcapsules had a median diameter of 0.23 ± 0.05 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.). To this capsule solution 859.1 parts, carboxy-modified styrene butadiene latex (trade name: SN-307, (48% aqueous solution), manufactured by Sumitomo Nougatac Co., Ltd.) 2.416 parts and ion-exchanged water 39.5 parts were mixed. An ultraviolet absorber precursor microcapsule solution was obtained.

(Preparation of coating solution for light transmittance adjusting layer)
1000 parts of the above-mentioned ultraviolet absorber precursor microcapsule solution, surfactant (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink & Chemicals, Inc.) 5.2 parts, 4% sodium hydroxide aqueous solution 7 .75 parts and (4-nonylphenoxytrioxyethylene) butyl sulfonate sodium (Sankyo Chemical Co., Ltd., 2.0% aqueous solution) 73.39 parts are mixed to obtain a coating solution for light transmittance adjusting layer. It was.

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

(Preparation of pigment dispersion for protective layer)
Barium sulfate (trade name: BF-21F, barium sulfate content 93% or more, manufactured by Sakai Chemical Industry Co., Ltd.) 8 parts anionic special polycarboxylic acid type polymer activator (trade name: Poise 532A (40% Aqueous solution), produced by Kao Co., Ltd.) 0.2 part and ion-exchanged water 11.8 parts were mixed and dispersed by dynomill to prepare a barium sulfate dispersion. As a result of particle size measurement (LA-910, manufactured by HORIBA, Ltd.), this dispersion was found to have a median diameter of 0.15 μm or less.
Colloidal silica (trade name: Snowtex O (20% aqueous dispersion), manufactured by Nissan Chemical Co., Ltd.) 17.7 parts is added to 40.0 parts of the barium sulfate dispersion, and the desired protective layer pigment is added. A dispersion was obtained.

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

(Preparation of coating solution for protective layer)
Fluorosurfactant (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink & Chemicals, Inc.), 40 parts, (4-nonylphenoxytrioxyethylene) on 1000 parts of the polyvinyl alcohol solution for protective layer 50 parts of sodium butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution), 49.87 parts of the pigment dispersion for protective layer, 16.65 parts of the matting agent dispersion for protective layer, zinc stearate 48.7 parts of a dispersion (trade name: Hydrin F115, 20.5% aqueous solution, manufactured by Chukyo Yushi Co., Ltd.) and 280 parts of ion-exchanged water were uniformly mixed to obtain a coating solution for a protective layer.

<Production of support>
(Preparation of coating solution for undercoat layer)
40 parts of enzyme-degraded gelatin (average molecular weight: 10000, PAGI viscosity: 1.5 mPa · s (15 mP), PAGI jelly strength: 20 g) is added to 60 parts of ion-exchanged water and dissolved under stirring at 40 ° C. An aqueous gelatin solution was prepared.
Separately, 8 parts of water-swelling synthetic mica (aspect ratio: 1000, trade name: Somasif ME100, manufactured by Co-op Chemical Co., Ltd.) and 92 parts of water were mixed, and then wet-dispersed with Viscomil, and the average particle size was 2.0 μm. A mica dispersion was obtained. Water was added to the mica dispersion so that the mica concentration was 5%, and the mixture was uniformly mixed to prepare a desired mica dispersion.

  120 parts of water and 556 parts of methanol were added to 100 parts of the 40% gelatin aqueous solution for undercoat at 40 ° C. and mixed well, and then 208 parts of 5% mica dispersion was added and mixed sufficiently. 9.8 parts of 66% polyethylene oxide surfactant was added. Then, the liquid temperature was kept at 35 to 40 ° C., and 7.3 parts of an epoxy compound gelatin hardener was added to prepare an undercoat layer coating solution (5.7%) to obtain an undercoat coating solution.

(Preparation of support with undercoat layer)
Wood pulp composed of 50 parts of LBPS and 50 parts of LBPK is beaten to 300 ml of Canadian freeness with a disk refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 1.0 part of aluminum sulfate, polyamide polyamine epichlorohydrin 0.1 parts and 0.5 parts of cationic polyacrylamide were added at an absolutely dry mass ratio with respect to the pulp, and a base paper having a basis weight of 114 g / m ² was made using a long paper machine, and a calendar process was performed to a thickness of 100 μm. It was adjusted.

Next, after corona discharge treatment was applied to both sides of the base paper, polyethylene was coated to a resin thickness of 36 μm using a melt extruder to form a resin layer consisting of a mat surface (this surface is referred to as “back surface”). Called). Next, a resin having a glossy surface is coated with polyethylene containing 10% anatase-type titanium dioxide and a trace amount of ultramarine using a melt extruder on the side opposite to the surface on which the resin layer is formed to a resin thickness of 50 μm. A layer was formed (this face is called the “front face”). After corona discharge treatment is applied to the polyethylene resin-coated surface of the back surface, aluminum oxide (trade name; Alumina Sol 100, manufactured by Nissan Chemical Industries, Ltd.) / Silicon dioxide (trade name; Snowtex O, Nissan Chemical Co., Ltd.) is used as an antistatic agent. (Made by Kogyo Co., Ltd.) = 1/2 (mass ratio) was dispersed in water and applied in an amount of 0.2 g / m ² after drying. Next, the polyethylene resin-coated surface on the front side was subjected to corona discharge treatment, and then the above-mentioned undercoat layer coating solution was applied so that the amount of mica applied was 0.26 g / m ² to obtain a support with an undercoat layer. It was.

<Application of coating solution for each thermosensitive recording layer>
From the bottom to the surface of the support with the undercoat layer, the thermal recording layer coating liquid (c), the intermediate layer coating liquid (intermediate layer A coating liquid), the thermal recording layer coating liquid (b), Seven layers were successively applied in the order of the intermediate layer coating solution (intermediate layer B coating solution), the thermosensitive recording layer coating solution (a), the light transmittance adjusting layer coating solution, and the protective layer coating solution. And dried at 30 ° C./humidity of 30% and 40 ° C./humidity of 30% to obtain multicolor heat-sensitive recording materials.
At this time, the coating amount of the thermal recording layer coating liquid (a) was adjusted so that the coating amount of the diazo compound contained in the liquid was 0.156 g / m ^{2 in} terms of the solid content coating amount. The coating amount of the layer coating solution (b) was adjusted so that the coating amount of the diazonium compound (D) contained in the solution was 0.206 g / m ^{2 in} terms of the solid coating amount. The coating amount of the coating solution (c) was adjusted so that the coating amount of the electron donating dye (H) contained in the solution was 0.355 g / m ^{2 in} terms of solid coating amount.

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

[Example 2]
4.4 parts of Exemplified Compound A-1 (diazo compound represented by General Formula (1)) used in Example 1 (Preparation of diazonium salt compound-encapsulating microcapsule solution (a)) -3 (a diazo compound represented by the general formula (1)) A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that 4.4 parts were used. In addition, the particle size of the obtained microcapsule was 0.40 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).

[Example 3]
The 1.3 parts of the isocyanate compound (1) solution used in Example 2 (preparation of diazonium salt compound-encapsulating microcapsule liquid (a)) was replaced with 1.3 parts of the isocyanate compound (2) solution. Except for the above, a multicolor thermosensitive recording material was obtained in the same manner as in Example 2. In addition, the particle size of the obtained microcapsule was 0.41 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).

[Example 4]
1.3 parts of the isocyanate compound (1) solution used in Example 2 (preparation of diazonium salt compound-encapsulated microcapsule liquid (a)) was replaced with 1.3 parts of the isocyanate compound (3) solution. Except for the above, a multicolor thermosensitive recording material was obtained in the same manner as in Example 2. In addition, the particle size of the obtained microcapsule was 0.40 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).

[Comparative Example 1]
4.4 parts of Exemplified Compound A-1 (diazo compound represented by the general formula (1)) used in Example 1 (Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)) was added to the following diazonium salt compound. (A) A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that 4.4 parts were used. In addition, the particle size of the obtained microcapsule was 0.43 μm in median diameter as a result of particle size measurement (LA-700, measured by HORIBA, Ltd.).

[Comparative Example 2]
The xylylene diisocyanate / trimethylolpropane adduct was used as a capsule wall material without using 1.3 parts of the isocyanate compound (1) used in (Preparation of diazonium salt compound-encapsulating microcapsule liquid (a)) in Example 1. And xylylene diisocyanate / bisphenol A adduct (trade name; Takenate D119N (50% ethyl acetate solution), manufactured by Mitsui Takeda Chemical Co., Ltd.) 8.6 parts were added in the same manner as in Example 1. A multicolor thermal recording material was obtained. The obtained microcapsules had a median diameter of 0.47 μm as a result of particle size measurement (LA-700, measured by Horiba, Ltd.).

<Evaluation>
The thermal recording sensitivity, photofixability, background preservation, and yellow stain of the white image of the multicolored thermal recording material obtained above were evaluated by the following procedure. The results are shown in Table 1 below.

(1) Evaluation of thermal recording sensitivity The multi-color thermal recording material was conditioned for 24 hours under an environmental condition of 23 ° C and humidity of 50%. Thereafter, a yellow, magenta, and cyan step wedge pattern was printed on the heat-sensitive recording material using NC370D (manufactured by Fuji Photo Film Co., Ltd.). One hour after printing, the optical reflection density of the halftone part of yellow, magenta, and cyan and the Dmax part was measured with an X-rite densitometer.

(2) Evaluation of light fixing property Each unprinted thermal recording material was exposed under an ultraviolet lamp having an emission center wavelength of 450 nm and an output of 40 W for various times, and then a thermal head (KST type) manufactured by Kyocera Corporation was used. The power applied to the thermal head and the pulse width were determined so that the recording energy per unit area was 23 mJ / mm ^2, and images were obtained by thermal printing on each thermal recording material. Next, the film was exposed to an ultraviolet lamp having an emission center wavelength of 450 nm and an output of 40 W for 10 seconds. The color density and the background density were measured. The color density with respect to the fixing time was plotted, and the inclination was calculated as the ratio of the inclination with respect to the heat-sensitive recording material of Comparative Example 2. The larger the number, the better the fixability.

(3) Background preservation The multicolored heat-sensitive recording material was treated for 7 days under environmental conditions of 50 ° C. and 70% humidity. Thereafter, the diazo compound was fixed by irradiation with an ultraviolet lamp having an emission center wavelength of 420 nm and an output of 40 W for 10 seconds, and then irradiation with an ultraviolet lamp having an emission center wavelength of 365 nm and an output of 40 W for 15 seconds.
The yellow optical reflection density of the background after 1 hour of fixing was measured with an X-rite densitometer to evaluate the background preservation. The lower the yellow optical reflection density, the better the background preservation.

(4) Evaluation of Yellow Stain in White Image Portion A multicolor heat-sensitive recording material was conditioned for 24 hours under an environmental condition of 23 ° C. and 50%. After humidity control, a white image was printed using NC370D (Fuji Photo Film Co., Ltd.). The color difference (L ^* a ^* b ^* ) in the white image portion was measured with an X-rite 938 color difference meter, and the degree of stain occurrence in the white image portion was evaluated with the value of b ^* . Note that the lower the value of b ^*, the lower the occurrence of yellow stain.

  As can be seen from Table 1, the heat-sensitive recording material of the present invention has high heat-recording sensitivity, excellent background preservation, little white image area stain, and good contrast.

Claims (4)

A thermosensitive recording material having a thermosensitive recording layer containing a diazo compound and a coupler on a support, and encapsulating in a microcapsule formed by polymerizing the diazo compound with a compound having active hydrogen and an isocyanate compound The diazo compound is a compound represented by the following general formula (1), and the isocyanate compound is a polyfunctional isocyanate compound and a polyamino acid having a terminal amino group represented by the following general formula (2). A heat-sensitive recording material which is a reaction product with an ether derivative.

(In the general formula (1), R ¹ represents a hydrogen atom, an alkyl group or an aryl group. R ² represents an alkyl group or an aryl group. R ³ , R ⁴ , R ⁵ and R ⁶ are each independently selected. Represents a hydrogen atom or a monovalent substituent, provided that at least one of R ³ , R ⁴ , R ⁵ and R ⁶ represents —N ₂ ⁺ X ^−, and X ⁻ represents an anion.)

(In General Formula (2), X represents a single bond, —CO— or —SO ₂ —. A represents an aryl group or an alkyl group. M represents 2 or 3. L represents an alkylene group. R represents an alkyl group, an aryl group, or an acyl group, and n represents 10 to 500.) _2. The heat-sensitive recording material according to claim 1, wherein in the general formula (1), R ⁵ is —N ₂ ⁺ X ⁻ and R ⁴ is an alkoxy group or an aryloxy group.   The heat-sensitive recording material according to claim 1 or 2, wherein in the general formula (2), A is an aryl group and m is 2. The heat-sensitive recording material according to any one of claims 1 to 3, wherein the coupler is a compound represented by the following general formula (3) or a tautomer thereof.

(In General Formula (3), E ¹ and E ² each independently represent an electron-withdrawing group. E ¹ and E ² may be bonded to each other to form a ring.)