JPH08230328A - Thermal responsive microcapsule, thermal recording material and multicolor thermal recording material using the microcapsule - Google Patents

Abstract

PURPOSE: To obtain a thermal responsive microcapsule showing high color forming properties and excellent in storage properties by using a specific polyfunctional isocyanate compd. in the capsule wall of a microcapsule including a diazonium salt or an electron donating dye precursor. CONSTITUTION: The capsule wall of a microcapsule including a diazo compd. or an electron donating dye precursor in a thermal recording material of a printer is prepared from a polymer obtained by polymerizing an isocyanate compd. composed of an adduct of a polyhydroxyl compd. composed of a polyhydric phenol compd. having three or more hydroxyl groups in its molecule represented by either one of formulae I, III (R<1> and R<2> are a hydrogen atom or a methoxymethyl group, R<3> is a hydrogen atom or a methyl group, R<4> is a methyl group or a group represented by formula II, R<6> is a hydrogen atom or a phenyl group and R<7> and R<8> are a methyl group or the like) and difunctional isocyanate having two isocyanate groups in its molecule and a compd. having two active hydrogen atoms in its molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoresponsive microcapsule which can be used as a thermosensitive recording material, a thermosensitive recording material using the microcapsule and a multicolor thermosensitive recording material.

[0002]

2. Description of the Related Art A heat-sensitive recording material which is widely used as a recording medium for facsimiles, printers and the like mainly uses a material obtained by applying a solid dispersion of an electron-donating dye precursor on a support and drying it. The recording method using the electron-donating dye precursor has an advantage that the material is easily available and exhibits a high color density and a high color developing speed, but it is easy to develop the color by the storage condition after heating or the adhesion of a solvent or the like. However, there are problems in the storability and reliability of recorded images, and many improvements have been studied.

As one method for improving the storability of a recorded image, an electron-donating dye precursor is encapsulated in microcapsules and the developer and the dye precursor are isolated from each other in the recording layer. , A method of improving the preservation of images has been proposed. With this method, high color developability and image stability can be obtained.

As a heat-sensitive recording material other than the above, so-called diazo-type heat-sensitive recording materials utilizing a diazonium salt have also been studied. This diazonium salt reacts with a phenol derivative or a compound having an active methylene group (coupler) to form a dye (usually a basic compound is used as a reaction accelerator), but it also has photosensitivity. However, it loses its activity upon irradiation with light.
Utilizing these properties, it has recently been applied to a heat-sensitive recording material, and a photo-fixing heat-sensitive recording material capable of forming an image by reacting a diazonium salt and a coupler with heat to form an image and then fixing it by irradiating with light. Proposed (Koji Sato et al., "Journal of the Institute of Image Electronics Engineers," Vol. 11, No. 4 (1982),
290-296, etc.).

However, since the recording material using the diazonium salt has high chemical activity, the diazonium salt and the coupler gradually react with each other during storage even at low temperature, and the storage life (shelf life) is short. There was a flaw. As one solution to this, a method of encapsulating a diazonium salt in a microcapsule and isolating it from a coupler, water, and a basic compound has been proposed (Usami Tomomasa et al., "Electrophotographic Society Journal", Vol. 26, No. 2). (1987), 115-12
Page 5).

As one of the fields of application of the heat-sensitive recording material, multicolor heat-sensitive recording material has been attracting attention. It has been said that reproduction of a multicolor image by thermal recording is more difficult than that of an electrophotographic recording method or an inkjet method. However, regarding this point, the electron-donating dye precursor encapsulated in a microcapsule on a support has already been used. To laminate two or more thermosensitive coloring layers containing a body and a color developer as main components or a diazonium salt encapsulated in a microcapsule and a coupler which reacts with the diazonium salt and develops a color when heated. It has been found that a multicolor thermosensitive recording material can be obtained. In such a multicolor thermosensitive recording material, it is required to control the thermocoloring property of the microcapsules to a high degree in order to obtain excellent color reproducibility as compared with the monochromatic thermosensitive recording material.

Conventionally, for encapsulating an electron-donating dye precursor or a diazonium salt compound in a microcapsule, generally, these compounds are dissolved in an organic solvent (oil phase),
This is added to an aqueous solution of a water-soluble polymer (aqueous phase) and emulsified and dispersed. At this time, by adding a monomer or prepolymer as a wall material to either the organic solvent phase side or the water phase side, a polymer wall is formed at the interface between the organic solvent phase and the water phase, and the microcapsules are formed. Can be converted.
These methods are described in detail in "Microcapsules" (Asamu Kondo, Nikkan Kogyo Shimbun (1970)) and "Microcapsules" (Tamotsu Kondo et al., Sankyo Publishing (1977)). As the formed microcapsule wall, various materials such as gelatin, alginate, celluloses, polyurea, polyurethane, melamine resin and polyamide (nylon) can be used. Among them, polyurea and polyurethane have a glass transition temperature of from room temperature to about 200 ° C., so that the capsule wall exhibits thermoresponsiveness,
It is suitable for designing a thermal recording material.

As a method for producing microcapsules, when obtaining microcapsules having a polyurethane or polyurea wall, first, a diazonium salt or an electron-donating dye precursor is dissolved in an organic solvent, and a polyvalent isocyanate compound is added thereto, This organic phase solution is emulsified in a water-soluble polymer aqueous solution. Thereafter, a method of forming a capsule wall by polymerizing a polyvalent isocyanate compound with a compound having active hydrogen such as water by adding a catalyst for accelerating the polymerization reaction to the aqueous phase or by raising the temperature of the emulsion is conventionally known. ing.

As the polyvalent isocyanate compound which is the material for forming the polyurea or polyurethane wall, for example, an adduct of 2,4-tolylene diisocyanate and trimethylol propane or an adduct of xylylene diisocyanate and trimethylol propane is used. Mainly used (JP-A-62-212190 and JP-A-4-212190)
No. 26189). However, even with a polyurea or polyurethane capsule wall using a polyvalent isocyanate compound as described above, the short shelf life when the above-mentioned diazonium salt is used has not been sufficiently improved. That is, a heat-sensitive recording material having a shelf life that is not sufficiently long has a background color called "fog" that appears when it is exposed to high temperature and high humidity conditions after manufacturing and before use. The visibility of the image is reduced. Therefore, it is required to further improve shelf life while maintaining high color development.

In the above-mentioned multicolor heat-sensitive recording material, cyan, magenta and yellow heat-sensitive recording layers are respectively provided, and these are printed by applying different heating temperatures. Further excellent thermal response is required as compared with the heat-sensitive recording layer. The above-mentioned conventional polyurea or polyurethane capsule wall cannot be said to sufficiently satisfy this requirement.

[0011]

DISCLOSURE OF THE INVENTION In order to further improve the shelf life while maintaining a high color developing property, the present inventor has a highly controllable thermochromic property of microcapsules required in a multicolor thermosensitive recording material. In order to obtain the above-described color development that can satisfy the above, from the examination of the type of microcapsule core-forming material such as electron-donating dye precursor or diazonium salt, microcapsule wall-forming material, type of surfactant, addition method, etc. As a result of intensive studies, particularly, the microcapsule wall forming material, the present invention has been achieved.
INDUSTRIAL APPLICABILITY The present invention exhibits high color development by contact with a coupler or a developer which can be suitably used for heat-sensitive recording materials and multicolor heat-sensitive recording materials, and has excellent thermal responsiveness with respect to storage properties (long shelf life). The purpose is to provide microcapsules. Another object of the present invention is to provide a heat-sensitive recording material having high sensitivity, high color developability and excellent storability. A further object of the present invention is to provide a multicolor heat-sensitive recording material having high sensitivity and excellent color reproducibility and storability.

[0012]

The present invention provides a microcapsule containing a diazo compound or an electron-donating dye precursor, wherein the capsule wall of the microcapsule has the following general formula (1):

[0013]

[Chemical 6] [However, R ¹ and R ² are each independently a hydrogen atom,
Represents a methyl group, a methoxymethyl group or a cycloalkyl group having 3 to 6 carbon atoms, and R ³ represents a hydrogen atom, a methyl group or

[0014]

[Chemical 7] (However, R ¹ and R ² have the same meanings as described above, and n
Is 1 or 2) and R ⁴ is a methyl group or

[0015]

Embedded image (However, R ¹ and R ² have the same meanings as described above, and n
Is 0, 1 or 2), and R ⁵ is

[0016]

[Chemical 9] (Provided that R ¹ and R ² have the same meanings as described above), but when R ⁵ represents a group having one hydroxyl group, either or both R ³ and R ⁴ have a hydroxyl group. Represents ] Or general formula (2):

[0017]

[Chemical 10] [However, R ⁶ represents a hydrogen atom, a methyl group, a phenyl group or a cyclohexyl group, and R ⁷ and R ⁸ are each independently a hydrogen atom, a methyl group, a methoxymethyl group or a cycloalkyl having 3 to 6 carbon atoms. Represents a group, and m represents 0 or 1. ] An isocyanate compound comprising an adduct of a polyhydroxyl compound comprising a polyhydric phenol compound having three or more hydroxyl groups in the molecule and a bifunctional isocyanate having two isocyanate groups in the molecule; A thermoresponsive microcapsule comprising a polymer obtained by polymerization with a compound having hydrogen (usually polyurethane or polyurethane / polyurea, and generally polyurethane / polyurea because water participates in the reaction).

The present invention also provides a support and a thermosensitive recording layer containing a diazo compound-encapsulating microcapsule and a coupler, or a microcapsule encapsulating an electron-donating dye precursor and a developer provided on the support. The heat-sensitive recording material according to the present invention, wherein the microcapsules are the thermoresponsive microcapsules described above.

Further, it has a transparent support and each of the cyan, magenta and yellow heat sensitive recording layers provided thereon, and each recording layer contains a microcapsule and a coupler containing a diazo compound, or an electron donating dye precursor. A multicolor thermosensitive recording material containing microcapsules containing a body and a color developer, wherein the microcapsules are the thermoresponsive microcapsules described above. .

Preferred embodiments of the microcapsules of the present invention are as follows. 1) The polyhydric phenol compound represented by the general formula (1) or (2) has a value of (inorganic) / (organic) of 0.3 to
It is a compound in the range of 1.0. 2) The polyhydroxyl compound has a polyhydric phenol compound represented by the general formula (1) or the general formula (2) and two or more hydroxy groups in the molecule in an equimolar amount or less of the polyhydric phenol compound. It has an aliphatic polyhydric alcohol compound. 3) The isocyanate compound is an adduct (A) of the polyhydroxyl compound (polyhydric phenol compound or a combination of a polyhydric phenol compound and an aliphatic polyhydric alcohol compound) with a bifunctional isocyanate, and 2 in the molecule.
The polyfunctional isocyanate compound (B) having at least one isocyanate group. The mixing ratio (A / B) of the adduct (A) and the polyfunctional isocyanate compound (B) is preferably in the range of 2/8 to 10/0 by weight,
The range of 5/5 to 9/1 is particularly preferable. 4) In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom, a methyl group, a methoxymethyl group or a cyclohexyl group. 5) In the general formula (2), R ⁶ represents a methyl group or a cyclohexyl group, R ⁷ and R ⁸ each independently represent a hydrogen atom or a cyclohexyl group, and m
Represents 0. 6) The compound having an active hydrogen atom used for forming the capsule wall of the microcapsule is water. 7) A diazonium salt or an electron donating dye precursor is dissolved in a high boiling point solvent and encapsulated in microcapsules.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoresponsive microcapsule of the present invention is a microcapsule containing a diazonium salt or an electron-donating dye precursor. The heat-sensitive recording material of the present invention has a basic structure in which a heat-sensitive recording layer containing the above-mentioned microcapsules is provided on a support. Further, the multicolor heat-sensitive recording material of the present invention has a basic constitution in which a heat-sensitive recording layer containing the above-mentioned microcapsules of cyan, magenta and yellow is provided on a transparent support (black surface may be provided on the back surface of the transparent support if desired) A thermal recording layer may be provided).

The thermoresponsive microcapsules of the present invention are microcapsules containing a diazonium salt or microcapsules containing an electron-donating dye precursor, and the capsule wall is represented by the above general formula (1) or (2). A polyhydric phenol compound having 3 or more hydroxyl groups in the molecule, or a polyhydroxyl compound comprising a combination of this polyhydric phenol compound and an aliphatic polyhydric alcohol compound, and 2 isocyanate groups in the molecule A polymer (polyurethane or polyurethane / polyurea) obtained by polymerizing an isocyanate compound consisting of an adduct with a functional isocyanate and a compound having active hydrogen such as water.

Specific examples of the polyhydric phenol compound represented by the above general formula (1) or (2) of the present invention include:
The following compounds may be mentioned.

[0024]

[Chemical 11]

[0025]

[Chemical 12]

[0026]

[Chemical 13]

[0027]

Embedded image

[0028]

[Chemical 15]

[0029]

Embedded image

[0030]

[Chemical 17]

[0031]

Embedded image

[0032]

[Chemical 19]

[0033]

Embedded image

[0034]

[Chemical 21]

[0035]

[Chemical formula 22]

[0036]

[Chemical formula 23]

[0037]

[Chemical formula 24]

The compounds P-1, P-2, P-3, P-4 and P-13 are particularly preferable.

In the present invention, among the polyhydric phenol compounds represented by the above general formula (1) or (2), the value of (inorganic) / (organic) is 0.3 to 1.0. Preference is given to using the compounds having. The numbers in parentheses in the above specific examples indicate the value of (inorganic) / (organic),
It was determined by calculation based on "Organic Conceptual Diagram-Basics and Applications" (Yoshio Koda, Sankyo Publishing Co., Ltd., 1984). The increase in (organic) of (inorganic) / (organic) mainly depends on the number of carbon atoms of the organic compound, and one carbon atom is calculated as 20. The increase in (inorganicity) mainly depends on the substituent of the organic compound, and one hydroxyl group is set to 100, and the influence on the boiling point of the group is determined as a standard. (Inorganic) / (Organic) in the above range
The value of is 1.0 for phenol, and it can be said that the polyhydric phenol compound in the above range has the same or higher ratio of hydrocarbons as compared with phenol. Isocyanate adduct obtained from this compound (polyfunctional isocyanate)
The capsule wall obtained by using has a low water content and moderate hydrophobicity, so diazonium salts, etc. encapsulated in the capsule enter the capsule wall or leave the capsule wall even under high temperature and high humidity environment. It rarely happens.

The polyhydroxyl compound of the present invention comprises a polyhydric phenol compound represented by the above general formula (1) or (2) and a compound having two or more hydroxyl groups other than this polyhydric phenol compound, It can be used in the range of equimolar or less to the phenol compound. As the polyhydroxyl compound used in combination, an aliphatic polyhydric alcohol compound is preferable. By using a compound having two or more hydroxyl groups other than the above-mentioned polyhydric phenol compound in combination, it is possible to reduce fogging especially under high humidity. In the present invention, the aliphatic polyhydric alcohol compound that can be used in combination with the polyhydric phenol compound may be a chain compound or a cyclic compound, and may have a substituent such as an aryl group. Further, as the aliphatic polyhydric alcohol compound, 2 to
Compounds having 5 (especially 3-4) hydroxyl groups are preferred. Further, the aliphatic polyhydric alcohol compound is a chain compound or a cyclic compound, and preferably has 2 to 12 carbon atoms (in particular, 3 to 8). Further, it may have an oxyalkylene group (preferably 1 to 3) such as an oxyethylene group or an oxypropylene group (particularly between the methine group and the hydroxyl group) in the molecule.

Examples of the aliphatic polyhydric alcohol compounds are: ethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-
Propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, pinacol, 1,6- Hexanediol, 1,
2-dodecanediol, 1,12-dodecanediol,
Diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol,
1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,
2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,3,5-cyclohexanetriol, trimethylolpropane, glycerol, pentaerythritol and dipentaerythritol, 1,4-
Benzene dimethanol, 3,3,3 ', 3'-tetramethyl-1,1'-spirobisindane-5,5', 6
6'-tetrol etc. can be mentioned. Of these, trimethylolpropane and 1,3,5-cyclohexanetriol are preferable, and trimethylolpropane is particularly preferable.

2 in a molecule which reacts with a polyhydroxyl compound such as the above polyhydric phenol compound to form an adduct.
A compound known as a bifunctional isocyanate having one isocyanate group can be used. They are,
Examples thereof include aromatic isocyanate compounds and aliphatic isocyanate compounds, and aromatic isocyanate compounds are particularly preferable. Specifically, the following can be mentioned.

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, 4,4'-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 (isocyanatomethyl) cyclohexane and 1,3
-Bis (isocyanatomethyl) cyclohexane. Among these, 2,4-tolylene diisocyanate, 2,6
-Tolylene diisocyanate, xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate are preferred, and xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate are particularly preferred.

An adduct of a polyhydric phenol compound having three or more hydroxyl groups in the molecule represented by the above general formula (1) or (2) and a bifunctional isocyanate having two isocyanate groups in the molecule. (A-1) is, for example, by heating a polyhydric phenol compound and a bifunctional isocyanate in an organic solvent with stirring (50 to 100 ° C.) or while adding a catalyst such as stannous octylate. It can be obtained by heating at a relatively low temperature (40 to 70 ° C.). Generally, 0.8 to 1.5 times the number of moles of the bifunctional isocyanate as the number of moles of the hydroxyl groups of the polyhydric phenol compound is used.

The adduct (A-2) of the combination of the above-mentioned polyhydric phenol compound and the aliphatic polyhydric alcohol compound and the bifunctional isocyanate having two isocyanate groups in the molecule is also the same as above, for example, , The above-mentioned polyhydric phenol compound, aliphatic polyhydric alcohol compound and bifunctional isocyanate are heated in an organic solvent with stirring (50
~ 100 ° C) or octylic acid first
Relatively low temperature (40-70 ℃) while adding catalyst such as tin
It can be obtained by heating at. Generally, the number of moles of hydroxyl groups of all polyhydroxyl compounds such as polyhydric phenol compounds and aliphatic polyhydric alcohol compounds is 0.
8 to 1.5 times the number of moles of difunctional isocyanate are used. Alternatively, the adduct (A-2) is obtained by obtaining an adduct of the polyhydric phenol compound and a bifunctional isocyanate having two isocyanate groups in the molecule, and then further adding the adduct and the aliphatic polyhydric alcohol. Obtaining by heating the compound in an organic solvent with stirring (50 to 100 ° C.) or by adding a catalyst such as stannous octylate at a relatively low temperature (40 to 70 ° C.). You can In addition, an aliphatic polyhydric alcohol compound and 2 in the molecule
After obtaining an adduct with a functional isocyanate by heating at a relatively low temperature (40 to 70 ° C.) while adding a catalyst such as stannous octylate, the adduct and the adduct of the polyhydric phenol compound are further added. It can be obtained by reacting in the same manner.

The molar ratio of the polyhydric phenol compound used to obtain the adduct (A-2) to the aliphatic polyhydric alcohol compound is 99: 1 to 50:50.
(Phenol: alcohol) is common, 90:10
60:40 is preferable, and 80:20 to 60:40 is particularly preferable.

As the isocyanate compound which is a raw material of the microcapsules, the polyhydric phenol compound of the present invention and 2
By combining an adduct with a functional isocyanate (A-1) or a combination of the above-mentioned polyhydric phenol compound and an aliphatic polyhydric alcohol compound with an adduct with a bifunctional isocyanate (A-2), two or more groups in the molecule It can be used in combination with another polyfunctional isocyanate compound having an isocyanate group. As such a polyfunctional isocyanate compound having two or more isocyanate groups in the molecule,
Known compounds such as xylene diisocyanate and hydrogenated products thereof, hexamethylene diisocyanate, tolylene diisocyanate and hydrogenated products thereof, and diisocyanates such as isophorone diisocyanate can be mentioned. Furthermore, these compounds as the main raw materials, and polyfunctional adducts (adducts) with these trimers (burette or isocyanurate) and polyols such as trimethylolpropane, and formalin condensates of benzene isocyanate. Can also be used.
In particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are used as a main raw material, and these trimers (burette or isocyanurate) are adducted with trimethylol propane to provide polyfunctionality. What was done is preferable. For these compounds, refer to "Polyurethane Resin Handbook" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun Ltd. (19
87)).

In the present invention, as the polyfunctional isocyanate compound having two or more isocyanate groups in the molecule, a bifunctional isocyanate compound represented by the following general formula may be used in combination at an appropriate ratio. Regarding these bifunctional isocyanate compounds, Japanese Patent Application No. 5-23
3536 and Japanese Patent Application No. 6-4714.

[0049]

[Chemical 25]

[Wherein, Ar represents an arylene group, X represents a single bond or a divalent group, R represents an alkylene group, an aralkylene group or an arylene group, and p represents an integer of 0-20. ]

[0051]

[Chemical formula 26]

[Wherein R is a hydrogen atom or an alkyl group, X is an aryl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a halogenated alkoxycarbonyl group, an aminocarbonyl group, an alkyl-substituted carbonyl group or an aryl-substituted aminocarbonyl group. , Y is an arylene group, an alkylene group or an aralkylene group, and k is 0
Or 1, p is an integer of 0 to 12, and q is 10
Represents an integer of 200. ]

The electron donating dye precursor contained in the microcapsules of the present invention includes triarylmethane compounds, diphenylmethane compounds, thiazine compounds,
Examples thereof include xanthene-based compounds and spiropyran-based compounds, but triarylmethane-based compounds and xanthene-based compounds are particularly useful because of their high color density.

Specific examples of these include 3,3-bis (p-dimethylaminophenyl) -6dimethylaminophthalide (ie, crystal violet lactone), 3,
3-bis (p-dimethylamino) phthalide, 3- (p-
Dimethylaminophenyl) -3- (1,3-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (o- Methyl-p-dimethylaminophenyl) -3- (2-methylindol-3-yl)
Phthalide, 4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenylleuco auramine, N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilinolactam, rhodamine ( p-nitroanilino) lactam, rhodamine-B
-(P-chloroanilino) lactam, 2-benzylamino-6-diethylaminofluorane, 2-anilino-6
-Diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3
-Methyl-6-cyclohexylmethylaminofluorane, 2-anilino-3-methyl-6-isoamylethylaminofluorane, 2- (o-chloroanilino) -6-
Diethylaminofluorane, 2-octylamino-6-
Diethylaminofluorane, 2-ethoxyethylamino-3-chloro-2-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane,
Benzoyl leuco methylene blue, p-nitrobenzyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,
3'-dichloro-spiro-dinaphthopyran, 3-benzylpyrodinaphthopyran, 3-propyl-spiro-dibenzopyran and the like can be mentioned.

Examples of the electron-accepting compound (developing agent (not included in the microcapsule)) used in combination with the electron-donating dye precursor are phenol derivatives such as bisphenols, salicylic acid derivatives and hydroxybenzoic acid ester derivatives. Is mentioned. Among these, bisphenols and hydroxybenzoic acid esters are particularly preferable. For example, 2,2-bis (p-hydroxyphenyl) propane (bisphenol A), 2,2-bis (p-hydroxyphenyl) pentane, 2,2-bis (p-hydroxyphenyl) ethane, 2,2-bis (P
-Hydroxyphenyl) butane, 2,2-bis (4'-
Hydroxy-3 ′, 5′-dichlorophenyl) propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) propane,
1,1- (p-hydroxyphenyl) pentane, 1,1
-(P-hydroxyphenyl) -2-ethylhexane,
3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (tert-butyl) salicylic acid and its polyvalent metal salt, 3-α, α-dimethylbenzylsalicylic acid and its polyvalent Mention may be made of metal salts, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol and p-cumylphenol. In the present invention, these electron-accepting compounds are
It is also possible to use one or more species in an arbitrary ratio.

A sensitizer for promoting the reaction is preferably added to the heat-sensitive recording layer composed of the electron-donating dye precursor and the electron-accepting compound. As the sensitizer, a low-melting-point organic compound having an aromatic group and a polar group in the molecule is preferable. Specific examples thereof include benzyl p-benzyloxybenzoate, α-naphthylbenzyl ether, β-naphthylbenzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p -Chlorobenzyl) ether, 1,4-butanediol phenyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m- Methyl phenyl ether, 1-phenoxy-2- (p-tolyloxy)
Examples thereof include ethane, 1-phenoxy-2- (p-ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane and p-benzylbiphenyl. In the present invention, two or more kinds of these sensitizers may be used together in an arbitrary ratio.

As the diazonium salt contained in the microcapsules of the present invention, known ones can be used. The diazonium salt is represented by the following general formula: ArN ₂ X ⁻ [wherein Ar represents an aryl group and X ⁻ represents an acid anion. ] The compound represented by these.

The above-mentioned diazonium salt is a compound which reacts with a phenol compound or a compound having active methylene to form a so-called dye, which is decomposed by irradiation with light (generally ultraviolet rays) and denitrified to lose its activity. is there. Specific examples of the diazonium salt include 2,5-dibutoxy-
4-morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-
Dibutoxy-4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzene Diazonium, 2,5-dibutoxy-4-tolylthiobenzenediazonium, 2,5-dibutoxy-4-chlorobenzenethiodiazonium, 3- (2-octyloxyethoxy)
-4-Morophorinobenzenediazonium, 4-N, N-
Dihexylamino-2-hexyloxybenzenediazonium, and 4-N-hexyl-N-tolylamino-2
Mention may be made of the salts of hexyloxybenzenediazonium.

The acid anion of the diazonium salt includes hexafluorophosphate, tetrafluoroborate,
Acid anions such as 1,5-naphthalene sulfonate, perfluoroalkyl carbonate, perfluoroalkyl sulfonate, zinc chloride and tin chloride can be used. Preferably, the acid anions of hexafluorophosphate, tetrafluoroborate and 1,5-naphthalene sulfonate are preferred because they have low water solubility and are soluble in organic solvents. In the present invention, two or more different diazonium salts can be mixed and used at an arbitrary ratio.

In the heat-sensitive recording layer using microcapsules containing a diazonium salt, a known heat sensitizer such as an arylsulfonamide compound may be added. Specific examples thereof include toluene sulfonamide and ethylbenzene sulfonamide. Further, in the present invention, two or more different thermal sensitizers may be mixed and used.

The coupler, which reacts with the diazonium salt to form a dye, is used in the form of fine particles by emulsion dispersion and / or solid dispersion. Specific examples of the coupler include resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-
Dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-
Hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyloxypurupyramide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide , Acetoacetanilide, benzoylacetanilide, 2-chloro-5-octylacetoacetanilide, 1-phenyl-3-methyl-5-pyrazolone, 1- (2'-octylphenyl) -3-methyl-5-pyrazolone, 1- ( 2 ', 4', 6'-Trichlorophenyl) -3-benzamido-5-pyrazolone, 1
-(2 ', 4', 6'-Trichlorophenyl) -3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamido-5-pyrazolone, 1- (2-dodecyloxyphenyl) -2-methylcarbonate Cyclohexane-3,5-dione, 1- (2-dodecyloxyphenyl) cyclohexane-3,5-dione, N-phenyl-
N-dodecyl barbituric acid, and N-phenyl-N-
Mention may be made of (3-stearyloxy) butyl barbituric acid. Two or more of these couplers may be used in combination to obtain a desired color hue.

Further, in order to accelerate the dye-forming reaction, it is general to add a base compound which is emulsified and / or solid-dispersed into fine particles. The basic substance includes not only an inorganic or organic basic compound, but also a compound that releases an alkaline substance by decomposition or the like when heated. Representative examples include organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. , Morpholines,
Examples thereof include nitrogen-containing compounds such as piperidines, amidines, formazines and pyridines. Specific examples of these include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine,
Allylurea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4
-Phenylimidazole, 2-phenyl-4-methylimidazole, 2-undecylimidazoline, 2,4,5
-Trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2-imidazoline, 2-phenyl-2-imidazoline, 1,2,3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1, Two
3-tricyclohexylguanidine, guanidine trichloroacetate, N, N'-dibenzylpiperazine, 4,
Mention may be made of 4'-dithiomorpholine, morpholinium trichloroacetate, 2-aminobenzothiazole and 2-benzoylhydrazinobenzothiazole.
These may be used in combination of two or more.

The thermoresponsive microcapsules of the present invention can be produced, for example, as follows. As the hydrophobic solvent for forming the core of the microcapsule, an organic solvent having a boiling point of 100 to 300 ° C. is preferable. Specifically, alkylnaphthalene, alkyldiphenylethane,
Alkyl diphenyl methane, diphenyl ethane alkyl adduct, alkyl biphenyl, chlorinated paraffin, phosphoric acid derivative such as tricresyl phosphate, maleic acid-di-
Examples thereof include maleic acid esters such as 2-ethylhexyl, and adipic acid esters. You may use these in mixture of 2 or more types. When the solubility of the diazonium salt or the electron-donating dye precursor in these hydrophobic solvents is not sufficient, a low boiling point solvent can be used together. The low boiling point organic solvent used in combination has a boiling point of 40.
Organic solvents at -100 ° C are preferable, and specific examples thereof include ethyl acetate, butyl acetate, methylene chloride, tetrahydrofuran and acetone. Moreover, you may use these in mixture of 2 or more types. When only a solvent with a low boiling point (boiling point of about 100 ° C or less) is used for the capsule core, the solvent evaporates, forming a so-called coreless capsule in which only the diazonium salt and the electron-donating dye precursor are present in the capsule wall. It is easy to be beaten.

Depending on the type of the diazonium salt, it may move to the aqueous phase side during the microencapsulation reaction, and in order to suppress this, the acid anion may be appropriately added in advance to the water-soluble polymer solution. Examples of the acid anion include PF ₆ ⁻ , B (−Ph) ₄ ⁻ [Ph is a phenyl group], Z
Examples thereof include nCl ₂ ⁻ , C _n H _{2n + 1} COO ⁻ (n is an integer of 1 to 9) and C _p F _{2p + 1} SO ₃ ⁻ (p is an integer of 1 to 9).

In the present invention, during microencapsulation,
As the compound having active hydrogen that reacts with the polyvalent isocyanate compound for forming the microcapsule wall,
Generally, water is used, but a polyol is added in an organic solvent as a core or in a water-soluble polymer solution as a dispersion medium to prepare a compound having the above active hydrogen (one of the raw materials for the microcapsule wall). Can be used. Specific examples include propylene glycol, glycerin and trimethylolpropane. Further, an amine compound such as diethylenetriamine or tetraethylenepentamine may be used instead of or in combination with the polyol. These compounds are also described in the above "Polyurethane Resin Handbook".

Water-soluble polymers for dispersing the oil phase of the microcapsules in the aqueous phase include polyvinyl alcohol and its modified products, polyacrylic acid amide and its derivatives, ethylene / vinyl acetate copolymer, styrene / anhydrous. Maleic acid copolymer, ethylene / maleic anhydride copolymer, isobutylene / maleic anhydride copolymer, polyvinylpyrrolidone, ethylene / acrylic acid copolymer, vinyl acetate / acrylic acid copolymer, carboxymethylcellulose, methylcellulose, casein , Gelatin, starch derivatives, gum arabic and sodium alginate. These water-soluble polymers are preferably those that do not react with the isocyanate compound or are extremely difficult to react with them. For example, those that have a reactive amino group in the molecular chain, such as gelatin, must have no reactivity in advance. is necessary.

In the microencapsulation, the surfactant may be used by adding it to either the oil phase or the water phase, but it is easier to add it to the water phase because of its low solubility in the organic solvent. The addition amount is 0.1 to the weight of the oil phase.
5% by weight, especially 0.5 to 2% by weight is preferred. Generally, surfactants having relatively long-chain hydrophobic groups are said to be excellent as surfactants used for emulsification and dispersion, and "Handbook of Surfactants" (Nishiichiro et al., Published by Sangyo Tosho (1980)), alkyls. Alkali metal salts such as sulfonic acid and alkylbenzene sulfonic acid can be used.

In the present invention, a surfactant (emulsification aid)
It is also possible to use a compound such as a formalin condensate of an aromatic sulfonate or a formalin condensate of an aromatic carboxylic acid. Specifically, the following general formula:

[0069]

[Chemical 27]

[R is an alkyl group having 1 to 4 carbon atoms,
X represents SO ₃ ⁻ or COO ⁻ , M represents a sodium atom or a potassium atom, and p represents an integer of 1 to 20]. The above compounds are described in Japanese Patent Application No. 5-83721.

Further, compounds of alkyl glucoside compounds can be used as well. Specifically, the following general formula:

[0072]

[Chemical 28]

A compound represented by [R represents an alkyl group having 4 to 18 carbon atoms and q represents an integer of 0 to 2]. In the present invention, any surfactant may be used alone or in combination of two or more kinds.

A mixed solution (oil phase) of the solution containing the above-mentioned diazonium salt (or electron-donating dye precursor), a high boiling point solvent and the like and the polyfunctional isocyanate compound (adduct) of the present invention is treated with a surfactant and a water-soluble agent. It is added to an aqueous solution (aqueous phase) composed of a water-soluble polymer. At that time, the aqueous solution is added while being stirred by a high shear stirring device such as a homogenizer to emulsify and disperse. After the emulsification, the polymerization reaction catalyst of the isocyanate compound is added or the temperature of the emulsion is raised to carry out the capsule wall forming reaction.

A coupling reaction deactivator can be appropriately added to the prepared microcapsule solution containing the diazonium salt. Examples of this reaction quencher include hydroquinone, sodium bisulfite, potassium nitrite, hypophosphorous acid, stannous chloride and formalin. These compounds are described in JP-A-60-214992. Usually, during the encapsulation process, the diazonium salt often elutes in the aqueous phase, but as a method for removing this, filtration treatment, ion exchange treatment, electrophoresis treatment, chromatography treatment,
Gel filtration treatment, reverse osmosis treatment, ultrafiltration treatment, dialysis treatment,
A method such as activated carbon treatment can be used. Among these, ion exchange treatment, reverse osmosis treatment, ultrafiltration treatment and dialysis treatment are preferable, and particularly, treatment with a cation exchanger,
Treatment with a combination of a cation exchanger and an anion exchanger is preferred. For these methods, see JP-A-61-219
No. 688.

In the present invention, an electron-accepting compound, a thermal sensitizer, a coupler and a basic compound can be added to the thermosensitive color developing layer. These are appropriately mixed, separately emulsified and dispersed, or solid dispersed, atomized and added, or appropriately mixed and then emulsified or solid dispersed,
It can be atomized and added. As a method of emulsifying and dispersing, these compounds are dissolved in an organic solvent, and a water-soluble polymer aqueous solution is added with stirring with a homogenizer or the like. In promoting the formation of fine particles, it is preferable to use the above-mentioned hydrophobic organic solvent, surfactant and water-soluble polymer.

In order to disperse the coupler, the basic substance, the electron-accepting compound, the thermal sensitizer and the like in a solid state, these powders are put into an aqueous solution of a water-soluble polymer and fine particles are formed by a known dispersing means such as a ball mill. And can be used.
It is preferable to make the particles fine so as to obtain a particle diameter that can satisfy the properties required for the multicolor thermosensitive recording material and the manufacturing method thereof, such as thermal sensitivity, storability, transparency of the recording layer, and suitability for manufacturing.

The above-mentioned microcapsule liquid and the above-mentioned preparation liquid of the heat sensitizer, electron-accepting compound, coupler, basic compound and the like are mixed in an appropriate ratio and coated on a support. Generally, 1 to 10 moles and 2 to 6 moles of couplers are suitable for 1 mole of diazonium salt. The optimum addition amount of the basic compound varies depending on the basic strength, but is generally 0.5 to 5 mol of the diazonium salt. The electron-accepting compound (developing agent) is generally added in the range of 0.5 to 30 mol, preferably 1 to 20 mol, per 1 mol of the electron-donating dye precursor. More preferably, it is added within the range of 3 to 15 mol. The thermal sensitizer is generally added within the range of 0.1 to 20 mol, preferably 0.5 to 10 mol, based on the electron-donating dye precursor.

As the support to which these coating liquids are applied, known materials for a heat-sensitive recording material can be used. Examples thereof include paper, coated paper obtained by applying clay or the like on paper, laminated paper obtained by laminating polyethylene, polyester, etc. on paper, synthetic paper, polyethylene terephthalate, polyimide, plastic film such as triacetyl cellulose. Examples of the transparent support include the above-mentioned polyethylene terephthalate, triacetyl cellulose, and plastic films of polystyrene, polypropylene, polyethylene and the like.

In the present invention, a protective layer may be provided on the thermosensitive coloring layer in order to further improve light fastness. Also,
In the multicolor thermosensitive material, an intermediate layer may be provided between the thermosensitive recording layers in order to further improve color reproducibility. The material of the layer used for these is preferably an emulsion (latex) of a water-soluble polymer compound or a hydrophobic polymer compound.

The multicolor thermosensitive recording material and the recording method thereof will be described. A multicolor thermosensitive recording material in which a third thermosensitive recording layer, a second thermosensitive recording layer and a first thermosensitive recording layer are sequentially formed on a support is developed in order from the outermost layer to form an image. First, the outermost heat-sensitive layer containing the diazonium salt (first heat-sensitive recording layer, usually a yellow color-developing layer) is developed by low-energy heat recording, and then the absorption wavelength range of the diazonium salt contained in the heat-sensitive layer is developed. The entire surface is irradiated with light using a light source that emits light, and the diazonium salt remaining in the uppermost heat-sensitive layer is photolyzed.

Then, the second heat-sensitive layer (second layer) containing a diazonium salt having a higher energy than the previous time and having a light absorption wavelength band different from the light in the absorption wavelength band of the diazonium salt contained in the first layer (first layer) (2) A thermosensitive recording layer (usually a magenta color-developing layer) is colored, and then the whole surface is irradiated again with a light source that emits light in the absorption wavelength range of the diazonium salt, whereby it remains in the second heating layer. Photolyze the diazonium salt. Finally, with higher energy, the innermost layer (third heat-sensitive recording layer, usually cyan coloring layer), the layer containing the electron-donating dye precursor (third layer) is colored to complete the image recording.

In the above case, it is preferable that the outermost layer and the second layer are transparent heat-sensitive layers because each color becomes vivid. In the present invention, a multicolor image can also be obtained by using a transparent support as the support and applying any one of the above three layers to the back surface of the transparent support. In this case, the uppermost heat-sensitive layer on the side opposite to the image viewing side does not need to be transparent.

An ultraviolet lamp is usually used as the light source used for the photolysis of the diazonium salt. An ultraviolet lamp is a fluorescent tube in which mercury vapor is filled in the tube, and fluorescent tubes having various emission wavelengths can be obtained depending on the type of fluorescent material applied to the inner wall of the tube.

In the multicolor heat-sensitive recording material, the third heat-sensitive recording layer may be made of a suitable combination of a diazonium salt and a coupler compound.

Examples will be shown below, but the present invention is not limited thereto. In addition, "part" in an Example shows all weight parts.

[0087]

【Example】

[Example 1] (I) Preparation of coating liquid for heat-sensitive recording layer (B) (1) Synthesis of isocyanate adduct m-xylylene diisocyanate (m-XDI) 30
1.1 g (1.60 mol) and the compound (P-2, I /
Polyhydric phenol compound 16 represented by O value: 0.62)
Ethyl acetate (470.7) with 9.6 g (0.40 mol)
g) To the suspension solution, a solution of 471 mg of stannous octylate (Stannocto, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) in 10 g of ethyl acetate was added dropwise over 1 hour while stirring. After the dropping, stirring was continued for 2 hours and then at 50 ° C. for 3 hours. Thus, a solution (50% by weight) of the isocyanate adduct (1) was obtained.

The terminal isocyanate compound obtained in the above reaction was converted to methylurethane with methanol and the molecular weight (polystyrene conversion value) was measured. The value obtained was 2720 in terms of number average molecular weight.

(2) Preparation of Diazonium Salt Capsule Emulsion 2.8 parts of the compound shown in (B-1) below having a maximum absorption wavelength of decomposition at 365 nm as a diazonium salt, dibutyl sulfate 2.8 parts, 2,2- 0.56 parts of dimethoxy-1,2-diphenylethan-1-one (Irgacure 651, manufactured by Ciba Geigy Co., Ltd.) was dissolved in 10.0 parts of ethyl acetate. Furthermore, 5.9 parts of isopropyl biphenyl, which is a high boiling point solvent, and 2.5 parts of tricresyl phosphate were added, and heated and mixed uniformly.

[0091]

[Chemical 29]

As the capsule wall forming material, 5.7 parts of the above-mentioned (1) isocyanate adduct (1) and xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75 wt% ethyl acetate solution, Takeda Yakuhin Co., Ltd.) were used. 3.8 parts) was further added to the above mixed solution and stirred uniformly. Separately, 6% by weight gelatin (trade name: MGP-9066, manufactured by Nippi Gelatin Industry Co., Ltd.) to which 2.0 parts of 10% by weight sodium dodecylsulfonate aqueous solution was added.
64 parts of an aqueous solution was prepared, the mixed solution of the above diazonium salt was added, and the mixture was emulsified and dispersed by a homogenizer.

(3) Encapsulation reaction After 20 parts of water was added to the obtained emulsion to homogenize it, the mixture was reacted at 40 ° C. for 30 minutes while stirring, and then heated to 60 ° C. for 3 hours. Was done. After that, the liquid temperature was lowered to 35 ° C. and the ion exchange resin Amberlite IRA6 was used.
8 (manufactured by Organo) 6.5 parts, Amberlite IRC5
13 parts of 0 (manufactured by Organo) were added, and the mixture was further stirred for 1 hour. After that, the ion exchange resin was filtered to obtain a target capsule liquid. The average particle size of the capsule was 0.64 μm.

(4) Preparation of Emulsion Dispersion of Coupler As a coupler, the compound (B-2) 3.0 shown below was used.
Part, triphenylguanidine 8.0 parts, 1,1- (p-
Hydroxyphenyl) -2-ethylhexane was 8.0
Part, 4,4 '-(p-phenylenediisopropylidene)
8.0 parts of diphenol, compound (B-3) shown below
2.0 parts, and 1,1,3-tris (2-methyl-4-)
2.0 parts of hydroxy-5-t-butylphenyl) butane was dissolved in 10.5 parts of ethyl acetate, and 0.48 parts of tricresyl phosphate as a high-boiling solvent, 0.24 parts of diethyl maleate and Pionine A41C ( Takemoto Yushi Co., Ltd.
(Manufactured by Mitsui Chemicals Co., Ltd.) and then heated and mixed uniformly.
This mixture was mixed with 8 wt% gelatin (# 750 gelatin,
This was added to 93 parts of Nitta Gelatin Co., Ltd. aqueous solution and emulsified and dispersed by a homogenizer. The remaining ethyl acetate was evaporated from this emulsion to obtain the target emulsion dispersion.

[0095]

Embedded image

[0096]

[Chemical 31]

(5) Preparation of coating solution The above diazonium salt capsule solution, coupler emulsion dispersion and styrene / butadiene rubber (SBR-SN307,
Sumitomo Nogatta Co., Ltd. was mixed so that the ratio of the diazonium salt / coupler was 1/2 and the ratio of the diazonium salt / styrene-butadiene rubber was 1 / 6.4 to obtain the desired coating liquid. A coating liquid for the heat-sensitive recording layer (B) was prepared.

(II) Preparation of coating liquid for heat-sensitive protective layer (D): 61 parts of 5.0 wt% aqueous solution of itaconic acid-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was added to 2 parts.
0.5 wt% zinc stearate dispersion (Hydrin F
115, manufactured by Chukyo Yushi Co., Ltd.) (2.0 parts by weight) was added, and 8.4 parts of a 2% by weight aqueous solution of the compound (D-1) shown below,
Fluorine-based release agent (ME-313, manufactured by Daikin) 8.0
Part, wheat flour starch (KF-4, Kagoshima Starch Co., Ltd.) 0.5
Parts were added and stirred uniformly. This is called mother liquor.

[0099]

Embedded image

Separately, 12.5 parts of ion-exchanged 20% by weight aqueous solution of chaogroth (manufactured by Shiraishi Industry Co., Ltd.), Poise 5
32A (manufactured by Kao Corporation) 0.06 part, Hydrin Z-7
(Manufactured by Chukyo Yushi Co., Ltd.) 1.87 parts, 10 wt% polyvinyl alcohol (PVA105, Kuraray Co., Ltd.) aqueous solution 1.25 parts, 2 wt% sodium dodecyl sulfonate aqueous solution 0.39 parts are mixed, Finely dispersed with a dyno mill. This liquid is called a pigment liquid. To 80 parts of the above mother liquor, 4.4 parts of the pigment liquid was added and stirred for 30 minutes or more. Then We
2.8 parts of tmaster500 (manufactured by Toho Chemical Co., Ltd.) was added, and the mixture was further stirred for 30 minutes or more to obtain a target coating solution for the heat-sensitive protective layer (D).

(III) Coating The heat-sensitive recording layer (B) was coated with a wire bar on a support for photographic paper obtained by laminating polyethylene on high-quality paper.
And the coating liquid for the protective layer (D) were sequentially coated and dried to obtain a heat-sensitive recording material. The coating amount as a solid content was 8 g and 1 g per 1 m ^2, respectively.

Example 2 In Example 1, the polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), the same amount of polyhydric phenol compound (the compound: P
-3, I / O value: 0.553), and a thermosensitive recording material was prepared in the same manner as in Example 1 except that the isocyanate adduct (2) was used.

[Example 3] In Example 1, the polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), the same amount of polyhydric phenol compound (the compound: P
-1, I / O value: 0.546) was used to prepare a thermosensitive recording material in the same manner as in Example 1 except that the isocyanate adduct (3) was used.

Example 4 In Example 1, a polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), the same amount of polyhydric phenol compound (the compound: P
-4, I / O value: 0.323) was used to prepare a thermosensitive recording material in the same manner as in Example 1 except that the isocyanate adduct (3) was used.

Example 5 In Example 1, a polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating liquid for the thermosensitive recording layer (B). Instead of the compound (the compound: P-2), a polyhydric phenol compound (the compound: P-1)
1, I / O value: 0.395) 284.4 g (0.40)
Mol) was used to prepare a thermosensitive recording material in the same manner as in Example 1 except that the isocyanate adduct obtained was used.

Example 6 In Example 1, a polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating solution for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), a polyhydric phenol compound (the compound: P-9,
A thermal recording material was prepared in the same manner as in Example 1 except that the isocyanate adduct obtained by using 132.0 g (0.30 mol) of I / O value: 0.793) was used.

Example 7 In Example 1, a polyhydric phenol was used in the synthesis of the isocyanate adduct (1) instead of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), a polyhydric phenol compound (the compound: P-1)
0, I / O value: 0.750) 167.1 g (0.30)
Mol) was used to prepare a thermosensitive recording material in the same manner as in Example 1 except that the isocyanate adduct obtained was used.

[Example 8] In Example 1, the polyhydric phenol was used in the synthesis of the isocyanate adduct (1) in place of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). Instead of the compound (the compound: P-2), a polyhydric phenol compound (the compound: P-1)
4, I / O value: 0.436) 250.0 g (0.40)
Mol) was used to prepare a thermosensitive recording material in the same manner as in Example 1 except that the isocyanate adduct obtained was used.

[Example 9] In Example 1, except that the isocyanate adduct (5) shown below was used in place of the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B). A thermal recording material was prepared in the same manner as in Example 1. Synthesis of polyvalent isocyanate compound (5) m-xylylene diisocyanate (m-XDI) 24
9.9 g (1.33 mol), polyhydric phenol compound (the compound: P-14, I / O value: 0.436) 206.
2 g (0.33 mol) and trimethylolpropane 14.
Ethyl acetate (470.7 with 4 g (0.11 mol))
g), a solution prepared by dissolving 391 mg of stannous octylate (Stannoct, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) in 10 g of ethyl acetate was added dropwise to the suspension solution over 1 hour while stirring. After the dropping, stirring was continued for 2 hours and then at 50 ° C. for 3 hours. Thus, a solution of the isocyanate adduct (5) (50% by weight) was obtained.

[Embodiment 10] In Embodiment 1, (2)
In the preparation of a diazonium salt capsule emulsion, 4.2 parts of isopropyl biphenyl and 4.2 parts of tricresyl phosphate were used in place of isopropyl biphenyl and tricresyl phosphate as the high boiling point solvent, and isocyanate addition was used as the capsule wall forming material. A thermal recording material was prepared in the same manner as in Example 1 except that 11.4 parts of the isocyanate adduct (1) was used instead of the compound (1) and the xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N). did.

[Example 11] In Example 2, (2) in the preparation of the diazonium salt capsule emulsion, 4.2 parts of isopropyl biphenyl and tricresyl phosphate were used instead of isopropyl biphenyl and tricresyl phosphate as the high boiling point solvent. And 4.2 parts of the isocyanate adduct (2) and 11.4 parts of the isocyanate adduct (2) instead of the xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N) as the capsule wall forming material. A thermal recording material was prepared in the same manner as in Example 2 except that it was used.

[Embodiment 12] In Embodiment 3, (2)
In the preparation of the diazonium salt capsule emulsion, 4.2 parts of isopropyl biphenyl and 4.2 parts of tricresyl phosphate were used in place of isopropyl biphenyl and tricresyl phosphate as the high boiling point solvent, and the isocyanate adduct was used as the capsule wall forming material. A heat-sensitive recording material was prepared in the same manner as in Example 3 except that 11.4 parts of the isocyanate adduct (3) was used instead of (3) and the xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N). .

[Embodiment 13] In Embodiment 1, (2)
In the preparation of a diazonium salt capsule emulsion, xylylene diisocyanate / trimethylol propane addition instead of isocyanate adduct (1) and xylylene diisocyanate / trimethylol propane adduct (Takenate D110N) as a capsule wall forming material Material (Takenate D110N) 4.5 parts and Japanese Patent Application No. 5-233536
5.7 parts of a xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in U.S. Pat. A thermal recording material was prepared in the same manner as in Example 1 except that the materials were mixed and used.

[Embodiment 14] In Embodiment 2, (2)
In the preparation of a diazonium salt capsule emulsion, xylylenediisocyanate / trimethylolpropane addition instead of isocyanate adduct (2) and xylylenediisocyanate / trimethylolpropane adduct (Takenate D110N) as a capsule wall forming material Material (Takenate D110N) 4.5 parts and Japanese Patent Application No. 5-233536
5.7 parts of a mixture of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in U.S. Pat. A thermal recording material was prepared in the same manner as in Example 2 except that the materials were mixed and used.

[Embodiment 15] In Embodiment 3, (2)
In the preparation of a diazonium salt capsule emulsion, as a capsule wall forming material, instead of an isocyanate adduct (3) part and a xylylene diisocyanate / trimethylol propane adduct (Takenate D110N), xylylene diisocyanate / trimethylol propane is used. 4.5 parts of additive (Takenate D110N) and Japanese Patent Application No. 5-233536
5.7 parts of a mixture of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in U.S. Pat. A thermal recording material was prepared in the same manner as in Example 3 except that the materials were mixed and used.

[Embodiment 16] In Embodiment 4, (2)
In the preparation of a diazonium salt capsule emulsion, xylylenediisocyanate / trimethylolpropane addition instead of isocyanate adduct (4) and xylylenediisocyanate / trimethylolpropane adduct (Takenate D110N) as a capsule wall forming material Material (Takenate D110N) 4.5 parts and Japanese Patent Application No. 5-233536
5.7 parts of a xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in U.S. Pat. A thermal recording material was prepared in the same manner as in Example 4 except that the materials were mixed and used.

[Embodiment 17] In Embodiment 1, (2)
In the preparation of a diazonium salt capsule emulsion, xylylene diisocyanate / trimethylol propane addition instead of isocyanate adduct (1) and xylylene diisocyanate / trimethylol propane adduct (Takenate D110N) as a capsule wall forming material Material (Takenate D110N) 4.5 parts and Japanese Patent Application No. 5-233536
2.28 parts of a mixture of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in U.S. Pat. A thermal recording material was prepared in the same manner as in Example 1 except that the materials were mixed and used.

[Comparative Example 1] In Example 1, (2) in the preparation of a diazonium salt capsule emulsion, an isocyanate adduct (1) and a xylylene diisocyanate / trimethylolpropane adduct (takenate) were used as capsule wall forming materials. Example 1 except that 7.6 parts of xylylene diisocyanate / trimethylolpropane adduct (75 wt% ethyl acetate solution, Takenate D110N, Takeda Pharmaceutical Co., Ltd.) was used in place of D110N). A heat sensitive recording material was obtained in the same manner.

[Comparative Example 2] In Example 1, the polyhydric phenol compound (P-) used in the synthesis of the polyvalent isocyanate compound (1) was prepared as the capsule wall forming material in the preparation of the (2) diazonium salt capsule emulsion. Example 1 except that the same amount of polyhydric phenol compound represented by the following (RP-1) (compound outside the scope of the present invention) was used instead of 2).
A thermal recording material was prepared in the same manner as in.

[0120]

[Chemical 33]

[Comparative Example 3] In Example 1, (2) in the preparation of the diazonium salt capsule emulsion, 4.2 parts of isopropyl biphenyl and tricresyl phosphate were used instead of isopropyl biphenyl and tricresyl phosphate as the high boiling point solvent. And 4.2 parts of the isocyanate adduct (1) and the xylylene diisocyanate / trimethylol propane adduct (Takenate D110N) as the capsule wall forming material. A thermosensitive recording material was prepared in the same manner as in Example 1 except that 11.4 parts was used.

[Comparative Example 4] The polyhydric phenol compound (P-2) used in the synthesis of the isocyanate adduct (1) in the preparation of the coating liquid for the thermosensitive recording layer (B) in Example 1
In place of the same amount of 0.30 of a polyhydric phenol compound represented by the following (RP-2) (a compound outside the scope of the present invention).
A thermal recording material was prepared in the same manner as in Example 1 except that the mole was used.

[0123]

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Comparative Example 5 The polyhydric phenol compound (P-2) used in Example 1 to prepare the isocyanate adduct (1) in the preparation of the coating liquid for the heat-sensitive recording layer (B).
A thermosensitive recording material was prepared in the same manner as in Example 1 except that the same amount of the polyhydric phenol compound represented by the following (RP-3) (a compound outside the scope of the present invention) was used instead of.

[0125]

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(IV) Evaluation of thermal recording characteristics The thermal recording characteristics of the above thermal recording materials were evaluated as follows using a thermal head KST type (manufactured by Kyocera Corp.). (1) The applied power to the thermal head and the pulse width were set so that the recording energy per unit area was 40 mJ / mm ^2, and printing was performed on the thermosensitive recording material to record a magenta image. (2) Use the recording material with an emission center wavelength of 365 nm and an output of 4
It was irradiated with a 0 W ultraviolet lamp for 15 seconds to fix the image on the unprinted portion. The color density of the magenta image was measured by measuring the optical reflection density of the printed portion with a Macbeth densitometer (RD918 type). The larger the value, the better. (3) Further, the shelf life (raw storability) was evaluated by storing the obtained thermosensitive recording material in a thermo-hygrostat kept at 40 ° C. and 90% relative humidity for 24 hours, and fixing the non-printed portion. Then, the optical reflection density of the non-printed portion (background portion) was measured.
The smaller the value, the better. The results are shown in Table 1.

[0127]

[Table 1] Table 1 ────────────────────────── Color density of the non-printed area of the printed area Color density of the image after fixing ──── ────────────────────── Example 1 1.05 0.07 Example 2 1.08 0.08 Example 3 1.12. 0.09 Example 4 0.99 0.09 Example 5 0.98 0.10 Example 6 0.98 0.10 Example 7 0.98 0.10 Example 8 1.05 0.10 Example 9 1.01 0.09 Example 10 0.98 0.10 Example 11 1.00 0.08 Example 12 1.10 0.08 Example 13 1.14 0.09 Example 14 1.00 0.08 Example 15 1.16 0.09 Example 16 1.03 0.08 Example 17 0.98 0.08 ───────────────────── Comparative Example 1 0.96 0.10 Comparative Example 2 1.00 0.40 Comparative Example 3 0.70 0.30 Comparative Example 4 0.70 0.30 Comparative Example 5 0.70 0.50 ──────────────────────────

[Example 18] (Preparation of coating liquid for heat-sensitive recording layer (A)) (1) Preparation of diazonium salt capsule liquid The following compound (A-1) having a maximum absorption wavelength of 420 nm as a diazonium salt for decomposition. 3.5 parts and compound (A
-2) 0.9 part was dissolved in 16.4 parts of ethyl acetate, 9.8 parts of isopropyl biphenyl as a high boiling point solvent was further added, and heated to uniformly mix.

[0129]

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[0130]

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4.5 parts of a xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution) as a capsule wall forming material was added to the above mixture and the method described in Japanese Patent Application No. 5-233536. Synthesized xylylene diisocyanate /
9 parts of a mixture of the bisphenol A adduct and 4.5 parts of a 30% by weight ethyl acetate solution were further added and stirred uniformly. Separately, ScraphAG-8 (manufactured by Nippon Seika Co., Ltd.) 0.3
77 parts of a 6% by weight gelatin aqueous solution containing 6 parts was prepared, the diazonium salt mixed solution (solution) was added, and the mixture was emulsified and dispersed by a homogenizer. 20 water is added to the obtained emulsion.
After parts were added and homogenized, the encapsulation reaction was carried out for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of an ion exchange resin Amberlite IRA68 (manufactured by Organo Co.) and 13 parts of Amberlite IRC50 (manufactured by Organo Co.) were added, and the mixture was further stirred for 1 hour. After that, the ion exchange resin was filtered, and then 0.4 parts of a 1 wt% hydroquinone aqueous solution was added to 10 parts of the capsule liquid, followed by stirring. In this way, a diazonium salt capsule liquid was obtained. The average particle size of the capsule was 0.91 μm.

(2) Preparation of Coupler Dispersion Liquid 2.4 parts of the following compound (A-3) and 4.1 parts of triphenylguanidine as a coupler, 1,1- (p-hydroxyphenyl) -2-ethylhexane 4 were used. 1st part, 4, 4 '
3.6 parts of-(p-phenylenediisopropylidene) diphenol and 0.8 parts of the following compound (A-4) were dissolved in 8.0 parts of ethyl acetate, and pionein A41C (manufactured by Takemoto Yushi Co., Ltd.). After adding 1.0 part, it heated and mixed uniformly.

[0133]

[Chemical 38]

[0134]

[Chemical Formula 39]

The above mixture was mixed with gelatin (#
750 gelatin, manufactured by Nitta Gelatin Co., Ltd., was added to 75.0 parts of a 10% by weight aqueous solution and emulsified and dispersed by a homogenizer. The remaining ethyl acetate was evaporated from this emulsion to obtain the target emulsion dispersion.

(3) Preparation of coating solution The above diazonium salt capsule solution, coupler emulsion dispersion, styrene-butadiene rubber (trade name SBR-SN3
07, Sumitomo Nogatac Co., Ltd.) were mixed so that the ratio of the diazonium salt and the coupler was 1 / 3.2, and the weight of the styrene / butadiene rubber was equal to the weight of gelatin of the coating solution. A coating liquid was prepared.

(Preparation of Coating Solution for Thermal Recording Layer (C)) (4) Preparation of Electron-Donating Dye Precursor Capsule Emulsion 3- (o-methyl-p-diethylaminophenyl) -as electron-donating dye precursor 0.39 parts of 3- (1'-ethyl-2-methylindol-3-yl) phthalide, 0.19 parts of 2-hydroxy-4-methoxybenzophenone having a maximum absorption wavelength at 285 nm as an ultraviolet absorber, and an antioxidant As a result, 0.25-part of 2,5-tert-octylhydroquinone was dissolved in 0.93 part of ethyl acetate,
Further, 0.54 parts of phenethylcumene, which is a high boiling point solvent, was added and heated to uniformly mix. As a capsule wall agent, 1.0 part of xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N) was further added to this solution and stirred uniformly. Separately, 36.4 parts of a 6% by weight gelatin (MGP-9066, manufactured by Nippi Gelatin Industry Co., Ltd.) aqueous solution to which 0.07 part of a 10% sodium dodecylsulfonate aqueous solution was added was prepared, and the electron-donating dye precursor was prepared. The body solution was added and emulsified and dispersed by a homogenizer. The emulsion dispersion thus obtained is called a primary emulsion dispersion. Separately, 6.0 parts of 3- (o-methyl-p-diethylaminophenyl) -3- (1'-ethyl-2-methylindol-3-yl) phthalide, 3.0 parts of 2-hydroxy-4-methoxybenzophenone and 2,
4.4 parts of 5-tert-octylhydroquinone was dissolved in 14.4 parts of ethyl acetate, 8.4 parts of phenethylcumene as a high boiling point solvent was further added, and the solution was stirred uniformly and the takenate previously used was added. 7.8 parts D110N and methylene diisocyanate (Millionate MR200,
5.9 parts of Nippon Polyurethane Co., Ltd. was added and stirred uniformly. The solution thus obtained and 1.2 parts of a 10% sodium dodecyl sulfonate aqueous solution were added to the above primary emulsified dispersion, and the mixture was emulsified and dispersed by a homogenizer.
The liquid thus obtained is called a secondary emulsion dispersion. 60.0 parts of water and 0.4 parts of diethylenetriamine were added to this secondary emulsified dispersion liquid to homogenize the mixture, and then the mixture was mixed with stirring 6
The temperature was raised to 5 ° C. and the encapsulation reaction was carried out for 3.5 hours to obtain a target capsule emulsion. The average particle size of the capsule is 1.
It was 9 μm.

(5) Preparation of Electron Accepting Compound Dispersion Liquid 30 parts of bisphenol P as an electron accepting compound was gelatin (MGP-9066, Nippi Gelatin Industry Co., Ltd.).
Manufactured by K.K.) to 82.5 parts of a 2.0% by weight aqueous solution, and further 7.5 parts of a 2% by weight aqueous solution of sodium 2-ethylhexylsulfosuccinate, and the resulting mixture is dispersed and dispersed in a ball mill for 24 hours. A liquid was prepared. To this dispersion was added 36.0 parts of a 15 wt% gelatin (# 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.) aqueous solution, and the mixture was stirred uniformly to obtain an electron-accepting compound dispersion. The average particle size of the electron-accepting compound in the dispersion was 0.5 μm.

(6) Preparation of coating liquid Next, the above-mentioned electron-donating dye precursor capsule liquid, electron-accepting compound dispersion liquid, 15 wt% gelatin (# 750 gelatin, Nitta Gelatin Co., Ltd.) aqueous solution and Stilbene-based optical brightener (Whitex-BB, manufactured by Sumitomo Chemical Co., Ltd.)
The ratio of electron-donating dye precursor / electron-accepting compound is 1/14, electron-donating dye precursor / # 750 gelatin =
1.1 / 1, and electron donor dye precursor / fluorescent whitening agent = 5.3 / 1 were mixed to prepare a target coating solution.

(7) Preparation of Liquid of Intermediate Layer (E) 8.2 parts of 4% by weight boric acid solution in 14% by weight gelatin (# 750 gelatin, Nitta Gelatin Co., Ltd.) aqueous solution,
1.2 parts of a 2 wt% aqueous solution of sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate and 7.5 parts of a 2 wt% aqueous solution of the following compound (E-1) were added,
The desired coating liquid was prepared by uniformly stirring.

[0141]

[Chemical 40]

(8) Coating On the surface of a printing paper support in which polyethylene is laminated on high-quality paper, a thermosensitive recording layer (C),
The intermediate layer (E), the heat-sensitive recording layer (B) described in Example 1, the intermediate layer (E), the heat-sensitive recording layer (A) and the protective layer (D) are applied and dried in this order to obtain the desired multicolor heat-sensitive property. A recording material was obtained.
The coating amount as solid content is 7 g, 3 g, and 8 per 1 m ² respectively.
It was g, 3 g, 6 g, and 1 g.

Example 19 The same as Example 18 except that (2) the diazonium salt capsule liquid described in Example 2 was used as the diazonium salt capsule liquid used in the thermosensitive coloring layer (B). A multicolor thermosensitive recording material was obtained.

(9) Evaluation of Thermal Recording Characteristics Using a thermal head KST type (manufactured by Kyocera Corp.), the thermal recording characteristics of the above thermal recording materials were evaluated as follows. (1) The applied power to the thermal head and the pulse width were adjusted so that the recording energy per unit area was 35 mJ / mm ^2, and printing was performed on the thermal recording material to record a yellow image. (2) Use the recording material with an emission center wavelength of 420 nm and an output of 4
It was irradiated with a 0 W ultraviolet lamp for 10 seconds, and (3) the applied power to the thermal head and the pulse width were determined again so that the recording energy per unit area was 80 mJ / mm ^2, and printing was performed to record a magenta image. . In addition, (4) 15 minutes with an ultraviolet lamp with an emission center wavelength of 365 nm and an output of 40 W
It was irradiated for 2 seconds, and (5) the applied power to the thermal head and the pulse width were adjusted again so that the recording energy per unit area was 140 mJ / mm ^2, and printing was performed to record a cyan image. As a result, in addition to the yellow, magenta, and cyan color-developed images, the recording area where the yellow and magenta recording overlap is red, the area where the magenta and cyan overlap is blue, and the area where the yellow and cyan overlap is green. , And the image portion where the yellow, magenta, and cyan recordings were overlapped developed a black color. The unrecorded area was grayish white.
The optical reflection densities of the yellow, magenta, and cyan color-developed portions were measured with a Macbeth RD918 densitometer. The shelf life (storability) was evaluated by leaving the obtained multicolor heat-sensitive recording material in a constant temperature and humidity bath kept at 40 ° C. and 90% relative humidity for 24 hours and then fixing it to determine the optical reflection density of the background part. It was measured.

The results obtained above are shown in Table 2.

[0146]

[Table 2] Table 2 ────────────────────────────── Color density of the printed area After fixing the non-printed area Yellow Magenta Cyan Color developed Concentration (magenta) ────────────────────────────── Example 18 0.80 1.00 1.20 0.12 Implementation Example 19 0.80 0.95 1.20 0.12 ───────────────────────────────

[0147]

The thermoresponsive microcapsules of the present invention are
It has excellent properties such as high sensitivity to heat, high color development by contact with a coupler or a color developer, and excellent storage properties (long shelf life) when a diazonium salt is used as a core material. Therefore, when the above-mentioned microcapsules are used for the heat-sensitive recording layer of the heat-sensitive recording material, a recording material having high sensitivity and high color developability and using a diazonium salt can be obtained with excellent storability. Further, when the above-mentioned microcapsules are used for a heat-sensitive recording layer (effectively used for a cyan color-developing layer which requires particularly high sensitivity), a multicolor heat-sensitive recording material having high sensitivity and excellent in color reproducibility and storability. Can be obtained.

Claims (4)

[Claims] 1. A microcapsule containing a diazonium salt or an electron-donating dye precursor, wherein the capsule wall of the microcapsule has the following general formula (1): [However, R ¹ and R ² are each independently a hydrogen atom,
Represents a methyl group, a methoxymethyl group or a cycloalkyl group having 3 to 6 carbon atoms, R ³ represents a hydrogen atom, a methyl group or (However, R ¹ and R ² have the same meanings as described above, and n
Is 1 or 2), R ⁴ is a methyl group or (However, R ¹ and R ² have the same meanings as described above, and n
Is 0, 1 or 2) and R ⁵ is (Provided that R ¹ and R ² have the same meanings as described above), and when R ⁵ represents a group having one hydroxyl group, either or both R ³ and R ⁴ have a hydroxyl group. Represents ] Or general formula (2): [However, R ⁶ represents a hydrogen atom, a methyl group, a phenyl group or a cyclohexyl group, and R ⁷ and R ⁸ are each independently a hydrogen atom, a methyl group, a methoxymethyl group or a cycloalkyl having 3 to 6 carbon atoms. Represents a group, and m represents 0 or 1. ] An isocyanate compound consisting of an adduct of a polyhydroxyl compound consisting of a polyhydric phenol compound having three or more hydroxyl groups in the molecule and a bifunctional isocyanate containing two isocyanate groups in the molecule; A thermoresponsive microcapsule, which is composed of a polymer obtained by polymerization with a compound having two or more active hydrogen atoms. 2. The polyhydroxyl compound comprises two or more polyhydric compounds represented by the general formula (1) or (2) in the molecule in an amount equal to or less than the equimolar amount of the polyhydric phenol compound. The thermoresponsive microcapsule according to claim 1, comprising an aliphatic polyhydric alcohol compound having a hydroxy group. 3. A thermosensitive recording comprising a support and a microcapsule and a coupler which encapsulates a diazonium salt and which is provided thereon, or a microcapsule which encapsulates an electron-donating dye precursor and a thermosensitive recording layer containing a color developer. A material, wherein the microcapsules are the thermoresponsive microcapsules according to claim 1 or 2. 4. A microcapsule and a coupler containing a transparent support and a thermosensitive recording layer of cyan, magenta and yellow provided thereon, each recording layer containing a diazo compound, or an electron-donating dye precursor. A multicolor heat-sensitive recording material containing a microcapsule enclosing a body and a color developer, wherein the microcapsule is the thermoresponsive microcapsule according to claim 1 or 2. Color heat-sensitive recording material.