JPH11550A - Thermoresponsive microcapsule, and thermosensitive recording material and multicolored thermosensitive recording material using that - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoresponsive microcapsule showing high color developing property and excellent raw preservability which can be suitably used for a thermosensitive recording material and a multicolored thermosensitive recording material and to provide the thermosensitive recording material and the multicolored thermosensitive recording material. SOLUTION: This microcapsule includes a diazo compd. or an electron donating dye precursor. The capsule wall of the microcapsule consists of a polymer obtd. by polymn. of a compd. having two active hydrogen atoms in the molecule and having at least one of a polyether chain, a polyester chain and a polysiloxane chain with 500 to 20000 average mol.wt., and an isocyanate compd. including an additon product with polyfunctional isocyanate having two or more isocyanate groups in the 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 for 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 thermosensitive recording material which is widely used as a recording medium for a facsimile, a printer or the like mainly uses a material obtained by applying and drying a solid dispersion of an electron-donating dye precursor on a support. The recording method using an electron-donating dye precursor has the advantage that the material is easily available and exhibits a high color density and a high color developing speed, but the color is easily formed by storage conditions after recording and adhesion of heating or a solvent. However, there are problems with the storability and reliability of recorded images, and many improvements have been studied.

One method for improving the storage stability of a recorded image is to encapsulate an electron-donating dye precursor in microcapsules and isolate the developer from the dye precursor in the recording layer. There have been proposed methods for improving the storability of images. With this method, high color developability and image stability can be obtained.

As a thermal recording material other than the above, a so-called diazo type thermal recording material utilizing a diazonium salt compound has been studied. The diazonium salt compound reacts with a phenol derivative or a compound having an active methylene group (a coupler) to form a dye, but also has photosensitivity and loses its activity by light irradiation. Utilizing these properties, it has recently been applied to heat-sensitive recording materials, and a light-fixing type heat-sensitive recording material that can form an image by reacting a diazo compound and a coupler with heat and then fix it by irradiating with light is developed. Has been proposed (Koji Sato et al., "Journal of the Institute of Image Electronics Engineers of Japan," Volume 11, Issue 4 (19
82), 290-296, etc.).

However, a recording material using a diazonium salt compound has a high chemical activity, so that the diazonium salt compound and the coupler gradually react even at a low temperature, resulting in a short shelf life (shelf life). there were. As one solution to this problem, a method has been proposed in which a diazonium salt compound is encapsulated in microcapsules and isolated from couplers, water, and basic compounds (Tomomasa Usami et al., "Journal of the Electrophotographic Society", Vol. 26, No. 2 (1987), 115
１２５125).

[0006] As one of application fields of the heat-sensitive recording material, a multicolor heat-sensitive recording material has been attracting attention. It has been said that the reproduction of a multicolor image by thermal recording is more difficult than the electrophotographic recording method or the ink-jet method, but in this regard, an electron-donating dye precursor and a developer have been mainly used on a support. It has been found that a multicolor thermosensitive recording material can be obtained by laminating two or more thermosensitive coloring layers as components or a thermosensitive coloring layer containing a diazonium salt compound and a coupler which reacts with the diazonium salt compound upon heating to form a color. ing. In the case of a multicolor heat-sensitive recording material, it is essential to control the thermal coloration characteristics of the microcapsules to a high degree in order to obtain excellent color reproducibility.

Conventionally, in order to incorporate an electron-donating dye precursor or a diazonium salt compound in microcapsules, 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 aqueous phase side, a polymer wall is formed at the interface between the organic solvent phase and the aqueous phase to perform microencapsulation. Can be. These methods are described in detail in "Microcapsules" (Asashi Kondo, Nikkan Kogyo Shimbun (1970)) and "Microcapsules" (Tamotsu Kondo et al., Sankyo Publishing (1977)). As the microcapsule wall to be formed, various materials such as gelatin, alginate, celluloses, polyurea, polyurethane, melamine resin, and nylon can be used. Polyurea and urethane resins have a glass transition temperature of about room temperature to about 200 ° C., so that the capsule wall exhibits thermal responsiveness and is suitable for designing a heat-sensitive recording material.

In the case of 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. The organic phase solution is emulsified in the aqueous polymer solution. Thereafter, a method of adding a catalyst for promoting a polymerization reaction to an aqueous phase or increasing the temperature of an emulsion to polymerize a polyvalent isocyanate compound with a compound having active hydrogen such as water to form a capsule wall is conventionally known. ing.

[0009] Examples of the polyvalent isocyanate compound which is a material for forming the polyurea or polyurethane wall include an adduct of 2,4-tolylene diisocyanate and trimethylolpropane, and an adduct of xylylene diisocyanate and trimethylolpropane. It is mainly used (JP-A-62-212190 and JP-A-4-212190).
However, even with a polyurea or polyurethane capsule wall using a polyvalent isocyanate compound as described above, the short shelf life when the above-described diazonium salt compound is used has not yet been sufficiently improved. . That is, a heat-sensitive recording material having a shelf life that is not sufficiently long exhibits a background color called "fog" when exposed to high temperature and high humidity conditions, for example, between the time of manufacture and use, and the printed image To reduce visibility. In order to solve such a problem, for example, there is a method of increasing the wall thickness of the microcapsule. However, the use of such a technique causes a reduction in color development sensitivity during thermal printing.
Therefore, it has been very difficult to further improve the shelf life while maintaining high color developability.

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. Hei 5-317694 discloses a method in which a polyhydric isocyanate compound is partially reacted with a monoalcohol compound before use. However, specific examples of the monoalcohol used in this case have 2 to 2 carbon atoms.
About 9 compounds. When the use rate of alcohol is increased, sensitivity is improved, but fog is increased. Conversely, fogging can be prevented by lowering the use rate of alcohol, but the effect of improving sensitivity is insufficient. Also, Japanese Patent Application Laid-Open No. 3-51178
In Japanese Patent Application Laid-Open Publication No. H10-157, a method using microcapsules formed from a polycarbonate compound having hydroxyl groups at both ends and a polyvalent isocyanate is known. However, in this case, it is used as a pressure-sensitive recording material, and although the heat resistance of the capsule wall is improved, the effect of improving sensitivity when used as a heat-sensitive recording material is insufficient. Further, as a similar compound, an adduct of a vinyl polymer having two hydroxyl groups at the polymer terminal and a divalent isocyanate compound is known in Japanese Patent Application No. 5-27054. However, even in these compounds, when the use rate of the compound is increased, the sensitivity is improved but the fog is increased. Conversely, when the usage rate is lowered, fogging can be prevented, but the effect of improving sensitivity is insufficient. These compounds also have the problem that the synthesis process is complicated and the cost is high.

Further, the multicolor heat-sensitive recording material is provided with cyan, magenta and yellow heat-sensitive recording layers, which are printed by applying different heating temperatures. Further excellent thermal responsiveness is required as compared with the heat-sensitive recording layer. The above-mentioned conventional polyurea or polyurethane capsule wall does not sufficiently satisfy this requirement.

Further, a heat sensitizer for improving heat sensitivity can be added to the heat-sensitive coloring layer of the heat-sensitive recording material. Examples of the thermal sensitizer include p-type compounds described in JP-B-6-55546.
-Toluenesulfonamide and the like are known to exhibit excellent performance, and examples of further excellent performance include arylsulfonamide compounds having a specific substituent described in Japanese Patent Application No. 7-191563. Can be In a multicolor heat-sensitive recording material, it is necessary to emulsify and use the above-mentioned arylsulfonamide compound in order to reduce the haze of the heat-sensitive coloring layer. The method of emulsification is not particularly limited, and a conventionally known method can be used. Specifically, the above arylsulfonamide compound is dissolved in an organic solvent that is hardly soluble or insoluble in water, and this is mixed with an aqueous phase having a surfactant and / or a water-soluble polymer as a protective colloid, stirred, and emulsified. Disperse. Details of the emulsification and dispersion are described in JP-A-2-141279.

However, since such a thermal sensitizer is usually a crystalline substance, an emulsion containing the same may cause problems such as precipitation of crystals over a long period of time. It has been desired to develop microcapsules having sufficient heat sensitivity without using a sensitizer or using a small amount.

[0014]

SUMMARY OF THE INVENTION The present inventors have developed a highly controllable thermo-coloring property of microcapsules required for multicolor thermosensitive recording materials in order to further improve shelf life while maintaining high color-forming properties. In order to obtain the above-described color developing property satisfying, a core-forming material of a microcapsule such as an electron-donating dye precursor or a diazonium salt compound,
Types of microcapsule wall forming materials, surfactants, etc.
As a result of intensive studies on the material for forming a microcapsule wall from among studies on the addition method and the like, the present invention has been reached. The present invention shows a high color-forming property by contact with a coupler or a color developer which can be suitably used for a heat-sensitive recording material and a multi-color heat-sensitive recording material, and without using a small amount of a heat sensitizer or a heat sensitizer. An object of the present invention is to provide a thermoresponsive microcapsule which has sufficient color developing properties and is excellent in raw preservability. Another object of the present invention is to provide a heat-sensitive recording material having high sensitivity, high color developing properties, and excellent raw storability (long shelf life). Another object of the present invention is to provide a multicolor heat-sensitive recording material having high sensitivity and excellent color reproducibility and raw preservability.

[0015]

According to the present invention, there is provided a microcapsule containing a diazo compound or an electron donating dye precursor, wherein the capsule wall of the microcapsule has at least one capsule wall in at least one kind of (A) molecule. Having at least one of a polyether chain, a polyester chain and a polysiloxane chain having an average molecular weight of 500 to 20,000, and (B) a polyfunctional compound having two or more isocyanate groups in the molecule. A thermoresponsive microcapsule comprising a polymer obtained by polymerization of an isocyanate compound containing an adduct with isocyanate; and

A heat-sensitive recording material comprising a support and a microcapsule containing a diazo compound provided thereon and a coupler, or a microcapsule containing an electron-donating dye precursor and a heat-sensitive recording layer containing a color developer. So,
A thermosensitive recording material, wherein the microcapsules are the thermoresponsive microcapsules described above;

A transparent support, and a cyan, magenta and yellow thermosensitive recording layer provided thereon, each recording layer including a microcapsule containing a diazo compound and a coupler, or an electron donating dye precursor. The present invention relates to a multicolor heat-sensitive recording material comprising a microcapsule and a developer, wherein at least one of the microcapsules is the above-mentioned heat-responsive microcapsule. Hereinafter, the present invention will be described in detail.

(A) At least one of a polyether chain, a polyester chain and a polysiloxane chain having two active hydrogens in the molecule and having an average molecular weight of 500 to 20,000.
The compound having a species will be described. Examples of the functional group having active hydrogen include a hydroxyl group, an amino group, and a carboxyl group. Of these, a hydroxyl group and an amino group are particularly preferred. When the molecular weight is smaller than 500, fogging increases due to the introduction of these compounds. On the other hand, if the molecular weight is more than 20,000, it becomes difficult to synthesize the compound, and the viscosity becomes high, so that it is difficult to prepare a liquid during encapsulation and to form a capsule.

More specifically, examples of the polyether include, for example, polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, poly (ethylenethioglycol), and copolymers thereof. Can be

As the polyester having hydroxyl groups at both ends, for example, a compound represented by the following general formula (1) or (2) can be used. H— (O—R ¹ —OCO—R ² —CO) _n —R ¹ —OH (1) wherein R ¹ is a diol residue, R ² is a dicarboxylic acid residue, and n is a positive integer HO— (R ³ —CO—O) _m —R ⁴ — (O—CO—R ³ ) ₁ —OH (2) wherein R ³ is a cyclic ester residue, a hydroxycarboxylic acid residue, a hydroxyester The residue, R ⁴ is a diol residue, and m and l are positive integers.] As the polysiloxane, for example, a polydimethylsiloxane derivative having a hydroxyl group at both terminals can be used. It is also possible to convert these terminal hydroxyl groups into terminal amino groups, carboxyl groups and the like by a known reaction.

The repeating unit of these compounds may be one type or a copolymer comprising two or more types of repeating units. These compounds may also have a melting point,
In such a case, a compound having a melting point of 40 to 180 ° C is particularly preferable. Examples of the compound having such a melting point include polyethylene oxide, polystyrene oxide, a polyester in which R ¹ is alkylene, phenylene, xylylene and the like in the above-mentioned general formula (1), R ² is phenylene and xylylene in the above-mentioned general formula (1) And polyesters in which R ³ is alkylene or the like in 2). Since this melting point varies depending on the molecular weight, it cannot be said unconditionally. For example, polyethylene oxide has such a melting point when the molecular weight is about 1,000 or more.

Among these, polyethylene oxide, polypropylene oxide, and R in the aforementioned general formula (1)
Particularly preferred are polyesters in which ¹ is alkylene and R ² is phenylene or the like, and polyesters in which R ³ is alkylene (for example, polycaprolactone) in the above general formula (2).

Next, (B) a polyfunctional isocyanate having two or more isocyanate groups in the molecule will be described. As such compounds, for example, compounds having two isocyanate groups in a molecule include 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, isophorone diisocyanate, lysine diisocyanate, etc. Is mentioned. Further, addition products of these bifunctional isocyanate compounds with low molecular bifunctional alcohols such as ethylene glycols and bisphenols, and phenols can also be used.

Further, polyfunctional isocyanate compounds can also be used. Examples of such a compound include the above-mentioned bifunctional isocyanate compound as a main raw material and a polyfunctional as an adduct of a trimer (buret or isocyanurate), a polyol such as trimethylolpropane, and a bifunctional isocyanate compound. , Isocyanate compounds having a polymerizable group such as methacryloyloxyethyl isocyanate, and lysine triisocyanate. 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 their trimers (buret or isocyanurate), adducts with trimethylolpropane are polyfunctional. Preferred is 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, especially xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, trimethylolpropane with xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate. Adducts are preferred.

The reaction ratio between the active hydrogen of (A) and the isocyanate group of (B) is 1/100 to 50/100 m
ol ratio, preferably 2/100 to 40/10
0 is particularly preferred. If the reaction ratio is less than 1/100, the effect of improving sensitivity is insufficient, and if it exceeds 50/100, the amount of isocyanate groups decreases, making it difficult to form capsules. The above-mentioned addition reaction between the active hydrogen of (A) and the isocyanate group of (B) is performed, for example, by heating both compounds in an organic solvent having no active hydrogen while stirring (about 50 to 100 ° C.). Or by heating at a relatively low temperature (about 40 to 70 ° C.) while adding a catalyst such as stannous octylate or dibutyltin diacetate. Examples of the organic solvent include, for example, ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like. The adduct of compound (A) and compound (B) may be one type or a mixture of two or more types.

In addition to the adduct of the compound (A) of the present invention and the compound (B), a known polyfunctional isocyanate having two or more isocyanate groups can be used as a raw material for the microcapsules. As an example of such a polyfunctional isocyanate, the compounds exemplified as the above-mentioned compound (B) can be used in combination at an appropriate ratio.

These polyfunctional isocyanate compounds are
They may be used alone or in combination of two or more. However, in this case,
The ratio of the compound (A) of the present invention to the polyfunctional isocyanate used in combination with the adduct of the compound (B) is 100/0 to 10/9.
A 0 weight ratio is preferred.

The polymerization of these isocyanate compounds is carried out, for example, by a reaction with a compound having two or more active hydrogen atoms in the molecule. Examples of such compounds include, in addition to water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyamine compounds such as ethylene diamine and diethylene triamine, and mixtures thereof. Of these, it is particularly preferable to carry out the polymerization using water. This results in the formation of a polyurethane / polyurea wall. The diazo compound or the electron-donating dye precursor is dissolved in a high boiling point solvent and encapsulated in microcapsules.

The thermoresponsive microcapsules of the present invention are microcapsules containing a diazo compound or an electron-donating dye precursor. Further, the heat-sensitive recording material of the present invention has a basic structure in which a heat-sensitive recording layer containing the microcapsules is provided on a support. Further, the multicolor heat-sensitive recording material of the present invention is provided with a heat-sensitive recording layer containing cyan, magenta, and yellow microcapsules on a transparent support, and at least one of these has a basic structure comprising the above microcapsules. (If desired, a black thermosensitive recording layer may be provided on the back surface of the transparent support).

The electron-donating dye precursor encapsulated in the microcapsules of the present invention includes a triarylmethane compound, a diphenylmethane compound, a thiazine compound,
Xanthene compounds, spiropyran compounds and the like can be mentioned. In particular, triarylmethane compounds and xanthene compounds are useful because of their high color density.

Specific examples thereof include 3,3-bis (p-dimethylaminophenyl) -6 dimethylaminophthalide (ie, crystal violet lactone),
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, 3- (o-methyl-p-diethylaminophenyl) -3- (1'-ethyl-2-methylindole-
3-yl) phthalide, 4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilino Lactam, rhodamine (p-nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam, 2-
Benzylamino-6-diethylaminofluoran, 2-
Anilino-6-diethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-
Anilino-3-methyl-6-cyclohexylmethylaminofluoran, 2-anilino-3-methyl-6-isoamylethylaminofluoran, 2- (o-chloroanilino) -6-diethylaminofluoran, 2-octylamino-6 -Diethylaminofluoran, 2-ethoxyethylamino-3-chloro-2-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, 3-methyl- Spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3
-Benzylpyridinaphthopyran, 3-propyl-spiro-dibenzopyran and the like.

Examples of the electron-accepting compound (color developer (not encapsulated in microcapsules)) used in combination with the above-mentioned electron-donating dye precursor include phenol derivatives, salicylic acid derivatives, and hydroxybenzoic acid esters. Of these, bisphenols and hydroxybenzoates are particularly preferred. 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 (te
rt-butyl) salicylic acid and its polyvalent metal salts, 3-
α, α-Dimethylbenzylsalicylic acid and its polyvalent metal salts, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol and p-cumylphenol be able to. In the present invention, two or more of these electron accepting compounds can be used in combination at any ratio.

It is preferable to add a sensitizer to the heat-sensitive recording layer to accelerate the reaction. As a sensitizer,
Low-melting-point organic compounds having an aromatic group and a polar group in the molecule are preferred. Specific examples thereof include p-benzyloxybenzyl benzoate, 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- Methylphenyl ether, 1-phenoxy-2- (p-tolyloxy) ethane, 1-phenoxy-2- (p-ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane, p-benzylbiphenyl, p-toluenesulfonamide, 4- (2-ethylhexylo) Shi)
Phenylsulfonamide, 4-n-pentyloxyphenylsulfonamide and the like. In the present invention, two or more of these sensitizers can be used in combination at any ratio.

As the diazonium salt compound encapsulated in the microcapsules of the present invention, known compounds can be used. The following general formula with a diazonium salt compound: ArN ₂ X ^- [wherein Ar represents an aryl group, and X ^- represents an acid anion. ] The compound represented by these.

The diazonium salt compound reacts with a phenol compound or a compound having active methylene,
It is capable of forming a so-called dye, and is further decomposed by irradiation of light (generally, ultraviolet light), denitrified, and loses its reaction activity. Specific examples of diazonium salts 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) benzenediazonium, 2,5-dibutoxy-4-
Tolylthiobenzenediazonium, 2,5-dibutoxy-4-chlorobenzenethiodiazonium, 2,5-diheptyloxy-4-chlorobenzenethiodiazonium,
3- (2-octyloxyethoxy) -4-morpholinobenzenediazonium, 4-N, N-dihexylamino-2-hexyloxybenzenediazonium, 4- (N
-Hexyl-N- (1-methyl-2- (p-methoxyphenoxy) ethyl) amino) -2-hexyloxybenzenediazonium and 4-N-hexyl-N-tolylamino-2-hexyloxybenzenediazonium salt. be able to.

The acid anion of the diazonium salt compound includes
Hexafluorophosphate salt, tetrafluoroborate salt, 1,5-naphthalene sulfonate salt, perfluoroalkyl carbonate salt, perfluoroalkyl sulfonate salt, zinc chloride salt, tin chloride salt and the like can be used. Preferably, a hexafluorophosphate salt, a tetrafluoroborate salt, and a 1,5-naphthalene sulfonate salt are suitable since they have low water solubility and are soluble in an organic solvent. In the present invention, two or more different diazonium salt compounds can be mixed and used in an arbitrary ratio.

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

The coupler which forms a dye by reacting with a diazonium salt compound is used in the form of fine particles by emulsification dispersion and / or solid dispersion. Specific examples of the coupler include resorcin, flurgurcine, 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-dodecyloxypropylamine, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetoanilide, 2-chloro-5-octylacetoacetanilide, 2,5 -Di-n-heptyloxyacetanilide, 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-methylcarbonatocyclohexane-3,5-dione, 1- (2-dodecyloxy Phenyl) cyclohexane-3,5-dione, N-phenyl-N-dodecylbarbituric acid, N-phenyl-N
-(2,5-dioctyloxyphenyl) barbituric acid and N-phenyl-N- (3-stearyloxy) butyl barbituric acid can be mentioned. These couplers can be used in combination of two or more to obtain a desired color hue.

Further, in order to accelerate the dye-forming reaction, it is common to add a basic compound which has been emulsified and / or solid-dispersed to form fine particles. The basic substance includes, in addition to inorganic or organic basic compounds, compounds that release an alkaline substance by decomposition or the like when heated. Representative examples include organic ammonium salts, organic amines, amides, ureas and thioureas and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles , Morpholines,
Examples include nitrogen-containing compounds such as piperidines, amidines, formazines, and pyridines. Specific examples of these include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine,
Allyl urea, thiourea, methyl thiourea, allyl thiourea, ethylene thiourea, 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, 2,
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, alkyl naphthalene, alkyl diphenyl ethane,
Phosphoric acid derivatives such as alkyl diphenylmethane, diphenylethane alkyl adduct, alkyl biphenyl, chlorinated paraffin, tricresyl phosphate, maleic esters such as maleic acid-di-2-ethylhexyl, and adipic esters be able to. These may be used as a mixture of two or more. When the solubility of the diazonium salt compound or the electron-donating dye precursor in these hydrophobic solvents is not sufficient, a low-boiling solvent can be further used. As the low boiling organic solvent used in combination, an organic solvent having a boiling point of 40 to 100 ° C. is preferable, and specific examples thereof include ethyl acetate, butyl acetate, methylene chloride, tetrahydrofuran, and acetone. These may be used in combination of two or more. When only a solvent having a low boiling point (having a boiling point of about 100 ° C. or less) is used for the capsule core, the solvent evaporates, and a so-called coreless capsule in which only the diazonium salt compound or the electron-donating dye precursor is present on the capsule wall. Easy to form.

Depending on the type of diazonium salt, micro
It may move to the aqueous phase during the encapsulation reaction.
In order to suppress the
May be appropriately added to the secondary solution. As this acid anion
Is PF₆ ^-, B (-Ph) _Four ^-[Ph is phenyl
Group), ZnCl_Two ^-, Cn H_{2n + 1}COO^-(N is 1 to 9
Integer) and Cp F_{2p + 1}SO_Three ^-(P is an integer from 1 to 9)
Can be mentioned.

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

Examples of the water-soluble polymer for dispersing the oil phase of the microcapsules in the aqueous phase include polyvinyl alcohol and its modified products, polyacrylamide and its derivatives, ethylene / vinyl acetate copolymer, and 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. It is preferable that these water-soluble polymers do not react with the isocyanate compound or very hardly react with them. For example, those having a reactive amino group in the molecular chain such as gelatin should be deactivated in advance. is necessary.

In the present invention, the surfactant may be added to either the oil phase or the aqueous phase, but it is easier to add the surfactant to the aqueous phase because of its low solubility in organic solvents.
The amount of addition is 0.1 to 5% by weight, especially 0.1% by weight, based on the weight of the oil phase.
5 to 2% by weight is preferred. Generally, surfactants used for emulsification and dispersion are considered to be excellent surfactants having a relatively long-chain hydrophobic group, and are described in "Surfactant Handbook" (Nishiichiro et al.,
Industrial book publication (1980)), and alkali metal salts such as alkylsulfonic acid and alkylbenzenesulfonic acid can be used.

In the present invention, a surfactant (emulsifier)
Compounds such as a formalin condensate of an aromatic sulfonate and a formalin condensate of an aromatic carboxylate can also be used. Specifically, the following general formula:

[0047]

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

[0050] Alkyl glucoside compounds can also be used. Specifically, the following general formula:

[0050]

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[R is an alkyl group having 4 to 18 carbon atoms, and q is an integer of 0 to 2]. In the present invention, any of the surfactants may be used alone or in combination of two or more.

A mixture (oil phase) of a solution comprising the above diazonium salt compound (or electron donating dye precursor), a solvent having a high boiling point and the like and the polyfunctional isocyanate compound (adduct) of the present invention is treated with a surfactant and It is added to an aqueous solution (water phase) composed of a water-soluble polymer. At this time, the aqueous solution is emulsified and dispersed by adding the aqueous solution while stirring it with a high shear stirring device such as a homogenizer. After the emulsification, a polymerization reaction catalyst for the isocyanate compound is added or the temperature of the emulsified product is increased to perform a capsule wall forming reaction.

To the prepared microcapsule solution containing a diazonium salt, a coupling quencher can be further added as appropriate. Examples of the reaction inactivating agent include hydroquinone, sodium bisulfite, potassium nitrite, hypophosphorous acid, stannous chloride and formalin. These compounds are described in JP-A-60-214992. In general, the diazonium salt compound often elutes in the aqueous phase during the encapsulation process, and as a method for removing this, filtration, ion exchange, electrophoresis, chromatography, gel filtration, reverse filtration, etc. Methods such as osmosis treatment, ultrafiltration treatment, dialysis treatment, and activated carbon treatment can be used. Of these, ion exchange treatment, reverse osmosis treatment, ultrafiltration treatment and dialysis treatment are preferred, and treatment with a cation exchanger and treatment with a combination of a cation exchanger and an anion exchanger are particularly preferred. These methods are described in
No. 1-219688.

In the present invention, an electron-accepting compound, a heat sensitizer, a coupler, a basic compound and the like can be added to the thermosensitive coloring layer. These are appropriately mixed, separately emulsified and dispersed, or solid dispersed, added after being atomized, or appropriately mixed, then emulsified and dispersed or solid dispersed,
It can be added after being atomized. In the method of emulsifying and dispersing, these compounds are dissolved in an organic solvent, and an aqueous solution of a water-soluble polymer is added with stirring using 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.

For solid dispersion of a coupler, a basic substance, an electron-accepting compound, a thermal sensitizer, etc., these powders are put into an aqueous solution of a water-soluble polymer, and fine particles are dispersed using a known dispersing means such as a ball mill. Can be used.
The fine particles are preferably formed so as to obtain a particle diameter that satisfies the properties required for the multicolor heat-sensitive recording material such as heat sensitivity, storage stability, transparency of the recording layer, and suitability for production, and the method for producing the same.

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

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

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

The multicolor heat-sensitive recording material and its recording method will be described. First, the outermost thermosensitive layer containing a diazonium compound (first thermosensitive recording layer, usually a yellow coloring layer) is colored by low-energy thermal recording, and then the absorption wavelength range of the diazonium compound contained in the thermosensitive layer is obtained. Irradiates the entire surface with a light source that emits light of the type described above to photodecompose the diazonium compound remaining in the uppermost thermosensitive layer.

Next, the second heat-sensitive layer (the second heat-sensitive layer) containing a diazonium compound having a higher energy than the previous time and having a light absorption wavelength range different from that of the diazonium compound contained in the first layer. (2) heat-sensitive recording layer, usually a magenta color-forming layer), and then irradiate the entire surface again with a light source that emits light in the absorption wavelength range of the diazonium compound, thereby remaining in the second heating layer. Photo-decomposed diazonium compound. Finally, the innermost layer (third heat-sensitive recording layer, usually a cyan coloring layer) containing the electron-donating dye precursor (third layer) is colored with higher energy to complete 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 a support and applying one of the three layers to the back surface of the transparent support. In this case, the uppermost thermosensitive layer on the side opposite to the image viewing side does not need to be transparent.

As a light source used for the photolysis of the diazonium compound, an ultraviolet lamp is usually used. The ultraviolet lamp is a fluorescent tube in which mercury vapor is filled in a tube, and a fluorescent tube having various emission wavelengths can be obtained depending on the type of phosphor applied to the inner wall of the tube.

In the multicolor heat-sensitive recording material, the third heat-sensitive recording layer can be formed by combining an appropriate diazonium salt compound and a coupler compound.

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

[0065]

【Example】

Synthesis Example 1 90 parts of polyethylene glycol (average molecular weight: 3000, melting point: about 64 ° C.) is dissolved in 112.6 parts of dry chloroform, and 9.5 parts of molecular sieve 4A is added. Drying is performed for 3 hours under a stream of dry nitrogen gas. Here, 22.6 parts of m-xylylene diisocyanate are added. In a water bath, 160 mg of stannous octoate (Stannoct, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) is added.
Thereafter, the mixture was stirred at 50 ° C. for 3 hours. Thus, a solution (50% by weight) of the isocyanate compound (1) was obtained.

[Synthesis Example 2] In a flask connected with a gas trap, 70.9 parts of 1,6-hexanediol and 109.6 parts of isophthalic dichloride were weighed, and the internal temperature was gradually raised. Since foaming occurs while melting gradually, the internal temperature is controlled while observing this state.
React at 00 ° C for 3 hours. By cooling this, a polyester having hydroxyl groups at both ends was obtained (in the general formula (1), R ¹ is hexamethylene, R ² is m-phenylene, the average molecular weight is about 2,400, and the melting point is about 80 ° C.). 40.0 parts of this polyester is dissolved in 106.7 parts of dry chloroform, and 2.0 parts of molecular sieve 4A is added.
Drying is performed for 3 hours under a stream of dry nitrogen gas. Here m-
53.3 parts of xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) are added. Stannous octoate in a water bath (Stanoct, Yoshitomi Pharmaceutical Co., Ltd.)
160 mg). Thereafter, the mixture was stirred at 50 ° C. for 3 hours. Thus, the isocyanate compound (2)
Was obtained (50% by weight).

Synthesis Example 3 In a flask connected with a gas trap, 70.9 parts of 1,6-hexanediol and 109.6 parts of terephthalic acid dichloride were weighed, and the internal temperature was gradually raised. Since foaming occurs while melting gradually, the internal temperature is controlled while observing this state.
React at 60 ° C for 3 hours. By cooling this, a polyester having hydroxyl groups at both terminals was obtained (in the general formula (1), R ¹ is hexamethylene, R ² is p-phenylene, the average molecular weight is about 2,400, and the melting point is about 132 ° C.). 70.6 parts of this polyester is dissolved in 186.4 parts of dry chloroform, and dried under a stream of dry nitrogen gas for 3 hours.
Here, 22.6 parts of m-xylylene diisocyanate are added. In a water bath, 160 mg of stannous octoate (Stannoct, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) is added. Thereafter, the mixture was stirred at 50 ° C. for 3 hours. Thus, a solution (50% by weight) of the isocyanate compound (3) was obtained.

[Synthesis Example 4] Ethylene glycol 1.24
Parts, 114.14 parts of ε-caprolactone at 100 ° C.
Heat and stir at 170 ° C for 40 hours. This is poured into 800 parts of a mixed solution of hexane / ethyl acetate = 4/1 to precipitate the polymer. This is filtered to obtain a polyester having hydroxyl groups at both ends (in formula (2), R ³ is pentamethylene, R ⁴ is ethylene, and the average molecular weight is about 500).
0, melting point: about 60 ° C.). 50.0 parts of this polyester is dissolved in 83.3 parts of dry chloroform, and 5.0 parts of Molecular Sieve 4A is added. Drying is performed for 3 hours under a stream of dry nitrogen gas. To this, 66.7 parts of m-xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) is added. Stannous octylate in a water bath (Stanoct, manufactured by Yoshitomi Pharmaceutical Co., Ltd.)
Add 160 mg. Thereafter, the mixture was stirred at 50 ° C. for 3 hours. Thus, a solution (50% by weight) of the isocyanate compound (4) was obtained.

[Synthesis Example 5] n-butyl alcohol 2.5
Part, polyvalent isocyanate compound (xylylene diisocyanate / trimethylolpropane adduct (takenate D
110N, 75% by weight ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.
Was dissolved in 52.5 parts of ethyl acetate. Stannous octoate in a water bath (Stanoct, Yoshitomi Pharmaceutical Co., Ltd.)
80 mg). The mixture was stirred at room temperature for 1 hour and then at 50 ° C. for 3 hours. Thus, a solution (50% by weight) of the isocyanate compound (5) was obtained.

Example 1 (I) Preparation of Coating Solution for Thermosensitive Recording Layer (A) (1) Preparation of Diazonium Salt Compound Solution The following compound (A-A) having a maximum absorption wavelength of decomposition at 420 nm as a diazonium salt compound was prepared. 1) Dissolve 3.5 parts and 0.9 part of compound (A-2) in 16.4 parts of ethyl acetate, and add 7.3 parts of isopropyl biphenyl which is a high boiling point solvent and 2.5 parts of dibutyl phthalate. , Heated and mixed uniformly.

[0072]

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Synthesis Example 1 of the above mixture as a capsule wall material, 3.0 parts of an xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) Was added, and the mixture was uniformly stirred. Separately, 77 parts of a 6% by weight aqueous gelatin solution to which 0.36 parts of ScrapAG-8 (manufactured by Nippon Seika Co., Ltd.) has been added is prepared. Emulsified and dispersed. After adding 20 parts of water to the obtained emulsion and homogenizing it, 4
The encapsulation reaction was performed for 3 hours while stirring at 0 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., and 6.5 parts of ion-exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added.
The mixture was further stirred for 1 hour. Then, after filtering the ion exchange resin, 0.4 part of a 1% by weight aqueous solution of hydroquinone was added to 10 parts of the capsule liquid, followed by stirring. Thus, a capsule solution of the diezonium salt compound was obtained. The average particle size of the capsule was 1.1 μm.

(2) Preparation of Coupler Emulsion Dispersion 2.4 parts of 2,5-di-n-heptyloxyacetanilide and 2.5 parts of triphenylguanidine were used as couplers.
3.3 parts of 4- (2-ethylhexyloxy) phenylsulfonamide, 1.7 parts of 4-n-pentyloxyphenylsulfonamide, 5.0 parts of 4,4 '-(m-phenylenediisopropylidene) diphenol Was dissolved in 8.0 parts of ethyl acetate, and 1.0 part of Pionin A41C (manufactured by Takemoto Yushi Co., Ltd.) was added, followed by heating and uniform mixing. This mixture was mixed with a separately prepared 10% by weight aqueous solution of gelatin (# 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.) 7
In addition to 5.0 parts, the mixture was emulsified and dispersed with a homogenizer. The remaining ethyl acetate was evaporated from this emulsion to obtain a target emulsified dispersion.

(3) Preparation of Coating Solution The above-mentioned diazonium salt compound capsule solution, coupler emulsified dispersion, styrene / butadiene rubber (trade name: SBR-S)
N307, manufactured by Sumitomo Nogatack Co., Ltd.) such that the ratio of diazonium salt compound / coupler becomes 1 / 3.2 and the weight of styrene-butadiene rubber becomes equal to the weight of gelatin in the coating solution. Was prepared.

(II) Preparation of Coating Solution for Heat-Sensitive Protective Layer (D) 5.0 parts by weight of an itaconic acid-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.)
0.5 wt% zinc stearate dispersion (Hydrin F
115, manufactured by Chukyo Yushi Co., Ltd.), and 8.4 parts of a 2% by weight aqueous solution of the following compound (D-1):
Fluorine release agent (ME-313, manufactured by Daikin) 8.0
Part, flour starch (KF-4, manufactured by Kagoshima Starch Co., Ltd.) 0.5
Was added and stirred uniformly. This is called mother liquor.

D-1 C ₁₂ H ₂₅ O- (C ₂ H ₄ O) ₁₀ -H

Separately, 12.5 parts of a 20% by weight aqueous solution of ion-exchanged chaogloss (manufactured by Shiraishi Industry Co., Ltd.),
32A (manufactured by Kao Corporation) 0.06 parts, Hydrin Z-7
1.87 parts (manufactured by Chukyo Yushi Co., Ltd.), 1.25 parts of a 10% by weight aqueous solution of polyvinyl alcohol (PVA105, Kuraray Co., Ltd.), and 0.39 part of a 2% by weight aqueous solution of sodium dodecyl sulfonate were mixed. Fine dispersion was performed using a dyno mill. This liquid is called a pigment liquid. 4.4 parts of the pigment liquid was added to 80 parts of the mother liquor, and the mixture was stirred for 30 minutes or more. Then we
Add 2.8 parts of tmaster500 (manufactured by Toho Chemical Co.), and add 3
The mixture was stirred for 0 minutes or more to obtain the intended coating solution for the heat-sensitive protective layer (D).

(III) Coating The heat-sensitive recording layer (A) and the protective layer (D) are coated and dried in this order on a surface of a photographic paper support obtained by laminating polyethylene on a high-quality paper with a wire bar. A heat-sensitive recording material was obtained. The application amounts as solids were 4.5 g and 1 g, respectively, per m 2.

(IV) Thermal Recording Using a thermal head KST type (manufactured by Kyocera Corporation), the thermal recording characteristics of the above-mentioned thermosensitive recording material were evaluated as follows. (1) The power applied to the thermal head and the pulse width were set so that the recording energy per unit area was 34 mJ / mm2, and printing was performed on the thermosensitive recording material to record a yellow image. (2) The recording material is made to have an emission center wavelength of 420 nm and output of 4
Irradiation was performed for 10 seconds with a 0 W ultraviolet lamp to fix an image in an unprinted portion. The color density of the yellow image was determined by measuring the optical reflection density of the color portion using a Macbeth densitometer (RD918). The results are shown as the color density in Table 1. (3) The shelf life (raw storage) was evaluated by storing the obtained heat-sensitive recording material in a thermo-hygrostat kept at 40 ° C. and a relative humidity of 90% for 24 hours, and then fixing the non-printed portion. The optical reflection density of the background was measured. The results are shown as fog density in Table 1.

Example 2 Xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) as a capsule wall material in the preparation of the capsule solution described in Example 1 ) A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 4.6 parts and 2.3 parts of the isocyanate compound (2) described in Synthesis Example 2 were used. The average particle size of the capsule is 0.
It was 9 μm.

Example 3 The isocyanate compound (3) described in Synthesis Example 3 was used instead of the isocyanate compound (1) described in Synthesis Example 1 as a capsule wall material in the preparation of the capsule liquid described in Example 1. Otherwise, the procedure of Example 1 was repeated to prepare a thermosensitive recording material. The average particle size of the capsule was 1.8 μm.

[Example 4] Xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.) was used as a capsule wall material in the preparation of the capsule liquid described in Example 1. 6.5 parts of a mixture of 4.5 parts) and 4.5 parts of a 30% by weight ethyl acetate solution of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in Japanese Patent Application No. 5-233536. Example 1 except that 2.3 parts of the isocyanate compound (4) described in Synthesis Example 4 was used.
A capsule liquid was obtained in the same manner as described above. The average particle size of the capsule was 0.9 μm.

[Comparative Example 1] In the preparation of the capsule liquid described in Example 1, as a capsule wall material, xylylene diisocyanate / trimethylolpropane adduct (takenate D110N, 75% by weight ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.) Capsule solution was obtained in the same manner as in Example 1 except that 6.0 parts of the above-mentioned product were used and the isocyanate compound (1) described in Synthesis Example 1 was not used. The average particle size of the capsule is 1.1 μm
Met. This capsule liquid was used in the same manner as in Example 1 to obtain a thermosensitive recording material.

[Comparative Example 2] In the preparation of the capsule liquid described in Example 1, as a capsule wall material, a xylylene diisocyanate / trimethylolpropane adduct (takenate D110N, 75% by weight ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.) 8.6 parts of a mixture of 4.5 parts and 4.5 parts of a 30% by weight ethyl acetate solution of xylylene diisocyanate / bisphenol A adduct synthesized according to the method described in Japanese Patent Application No. 5-233536. A capsule liquid was obtained in the same manner as in Example 1 except that the isocyanate compound (1) described in Synthesis Example 1 was not used. The average particle size of the capsule was 1.0 μm. This capsule liquid was used in the same manner as in Example 1 to obtain a thermosensitive recording material.

Comparative Example 3 Xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.) 6.0 parts as the capsule wall material described in Comparative Example 1 Was used in the same manner as in Example 1 except that 9.0 parts of the isocyanate compound (5) described in Synthesis Example 5 was used. The average particle size of the capsule was 1.1 μm.

The heat-sensitive recording material obtained above (Examples 2 to 5)
4 and Comparative Examples 1 to 3, the color density and the density of the non-colored portion were measured in the same manner as in the thermal recording of Example 1. Table 1 shows the results.

Table 1 色 Coloring density Fog density ────────────── {Example 1 0.75 0.09 Example 2 0.75 0.13 Example 3 0.75 0.13 Example 4 0.82 0.10} ──────────────────────── Comparative Example 1 0.48 0.12 Comparative Example 2 0.60 0.13 Comparative Example 3 0.53 0. 13 ──────────────────────────

Example 5 2.4 parts of 2,5-di-n-heptyloxyacetanilide, 1.2 parts of triphenylguanidine, and 4,4 '
An emulsified dispersion was prepared in the same manner as in Example 1 except that 2.4 parts of-(m-phenylenediisopropylidene) diphenol was dissolved in 8.0 parts of ethyl acetate, and the mixture was heated and uniformly mixed. A recording material was obtained. The coating amount as a solid content of the heat-sensitive recording layer was 3.2 g / m 2.

Comparative Example 4 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the capsule liquid described in Comparative Example 2 was used and the coupler dispersion described in Example 5 was used.

For the heat-sensitive recording materials obtained above (Example 5 and Comparative Example 4), the color density and the density of the non-color-formed portion were measured in the same manner as in the heat recording of Example 1. Table-
It is shown in FIG.

Table 2 色 Coloring density Fog density ────────────── ──────────── Example 5 0.65 0.12 比較 Comparative Example 4 0.20 0.12 ──────────────────────────

Example 6 (Preparation of coating solution for heat-sensitive recording layer (B)) As a diazonium salt compound, 2.8 parts of the compound shown in the following (B-1) having a maximum absorption wavelength of decomposition at 365 nm, dibutyl sulfate 2.8
Part, 2,2-dimethoxy-1,2-diphenylethane-
1-one (Irgacure 651, Ciba Geigy, Inc.)
(0.56 parts) was dissolved in 10.0 parts of ethyl acetate. Further, 5.9 of isopropyl biphenyl which is a high boiling point solvent is added.
Parts and 2.5 parts of tricresyl phosphate were added and mixed by heating.

[0094]

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As a capsule wall material, 7.6 parts of an xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% by weight ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) was further added to the above mixture, Stir evenly. Separately, 6 parts by weight of gelatin added with 2.0 parts of a 10% by weight aqueous solution of sodium dodecylsulfonate (trade name: MGP-9066, manufactured by Nippi Gelatin Industries Co., Ltd.)
64 parts of an aqueous solution was prepared, a mixed solution of the above diazonium salt compound was added, and the mixture was emulsified and dispersed with a homogenizer.

(3) Encapsulation reaction 20 parts of water was added to the obtained emulsion to homogenize, and the mixture was reacted at 40 ° C. for 30 minutes with stirring, then heated to 60 ° C. and encapsulated for 3 hours. Was performed. Thereafter, 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
0 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was filtered to obtain a desired capsule liquid. The average particle size of the capsule was 0.64 μm.

(4) Preparation of Coupler Emulsion Dispersion Compound (B-2) 3.0 shown below was used as a coupler.
Parts, triphenylguanidine 8.0 parts, 1,1- (p-
Hydroxyphenyl) -2-ethylhexane 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-tert-butylphenyl) butane are dissolved in 10.5 parts of ethyl acetate, and 0.48 part of tricresyl phosphate, a high boiling solvent, 0.24 part of diethyl maleate and pionin A41C ( Takemoto Yushi Co., Ltd.
Was added, and the mixture was heated and uniformly mixed.
This mixture was mixed with 8% by weight gelatin (# 750 gelatin,
The solution was added to 93 parts of an aqueous solution (manufactured by Nitta Gelatin Co., Ltd.) and emulsified and dispersed by a homogenizer. The remaining ethyl acetate was evaporated from this emulsion to obtain a target emulsified dispersion.

[0098]

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[0099]

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(Preparation of Coating Solution for Thermosensitive Recording Layer (C)) (4) Preparation of Electron-donating Dye Precursor Capsule Emulsion 3- (o-methyl-p-diethylaminophenyl)- 0.39 part of 3- (1'-ethyl-2-methylindol-3-yl) phthalide, 0.19 part of 2-hydroxy-4-methoxybenzophenone having a maximum absorption wavelength at 285 nm as an ultraviolet absorber, and an antioxidant Dissolve 0.29 parts of 2,5-tert-octylhydroquinone in 0.93 parts of ethyl acetate as
Further, 0.54 part of phenethyl cumene which is a high boiling point solvent was added, and the mixture was heated and uniformly mixed. As a capsule wall material, 1.0 part of xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N) was further added to this solution, and the mixture was stirred uniformly. Separately, 36.4 parts of a 6% by weight aqueous solution of gelatin (MGP-9066, manufactured by Nippi Gelatin Industries Co., Ltd.) to which 0.07 part of a 10% aqueous solution of sodium dodecyl sulfonate was added was prepared, and the above electron-donating dye precursor was prepared. The body solution was added and emulsified and dispersed with a homogenizer. The thus-obtained emulsified dispersion is referred to as a primary emulsified dispersion.

Separately, 6.0 parts of 3- (o-methyl-p-diethylaminophenyl) -3- (1'-ethyl-2-methylindol-3-yl) phthalide, 2-hydroxy-
3.0 parts of 4-methoxybenzophenone and 2,5-te
4.4 parts of rt-octylhydroquinone was dissolved in 14.4 parts of ethyl acetate, and 8.4 parts of phenethyl cumene, which is a high boiling point solvent, was added. The previously used Takenate D110N was added to a uniformly stirred solution. 7.8 parts and 5.9 parts of methylene diisocyanate (Millionate MR200, manufactured by Nippon Polyurethane Co., Ltd.) were added, and the mixture was stirred uniformly. The solution thus obtained and 1.2 parts of a 10% aqueous solution of sodium dodecylsulfonate were added to the primary emulsified dispersion and emulsified and dispersed with a homogenizer. The liquid obtained in this way is called a secondary emulsified dispersion. After adding 60.0 parts of water and 0.4 parts of diethylenetriamine to the secondary emulsified dispersion to homogenize, the mixture is heated to 65 ° C. with stirring, and an encapsulation reaction is performed for 3.5 hours to obtain the desired capsule. An emulsion was obtained. The average particle size of the capsule is 1.9 μm
Met.

(5) Preparation of Electron-Accepting Compound Dispersion As an electron-accepting compound, bisphenol P (30 parts) was gelatinized (MGP-9066, Nippi Gelatin Industry Co., Ltd.)
82.5 parts by weight of a 2.0% by weight aqueous solution, and 7.5 parts by weight of a 2% by weight aqueous solution of sodium 2-ethylhexylsulfosuccinate, and the resulting mixture was dispersed and dispersed by a ball mill for 24 hours. A liquid was prepared. To this dispersion was added 36.0 parts of a 15% by weight aqueous solution of gelatin (# 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 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 Solution Next, the above-mentioned capsule solution of the electron-donating dye precursor, the dispersion of the electron-accepting compound, a 15% by weight aqueous solution of gelatin (# 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.) and Stilbene-based fluorescent whitening agent (Whitex-BB, manufactured by Sumitomo Chemical Co., Ltd.)
The ratio of electron donor dye precursor / electron accepting compound is 1/14, electron donor dye precursor / # 750 gelatin =
1.1 / 1, and electron-donating dye precursor / fluorescent brightener = 5.3 / 1 to prepare a target coating solution.

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

E-1 (CH ₃ CH ₂ SO ₂ CH ₂ CONHCH ₂ ) _2-

(8) Coating The heat-sensitive recording layer (C) was coated with a wire bar on the surface of a photographic paper support in which polyethylene was laminated on high-quality paper.
The intermediate layer (E), the heat-sensitive recording layer (B), the intermediate layer (E), the heat-sensitive recording layer (A) and the protective layer (D) described in Example 1 are coated and dried in this order to obtain the desired multicolor heat-sensitive material. A recording material was obtained.
The application amount as solid content is 9g, 3g, 8m / m2 respectively.
g, 3 g, 4.5 g, and 1 g.

(9) Thermal Recording Using a thermal head KST type (manufactured by Kyocera Corp.), the thermal recording characteristics of the above-mentioned thermosensitive recording material were evaluated as follows. (1) The power applied 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 thermosensitive recording material to record a yellow image. (2) Using the recording material with a light emission center wavelength of 420
irradiate for 10 seconds with an ultraviolet lamp with a power of 40 W
(3) The recording energy per unit area is again 80 mJ / m
applying power to the thermal head such that m ^2, determines the pulse width, and printed, were recorded images of magenta. Further, (4) irradiation with an ultraviolet lamp having an emission center wavelength of 365 nm and an output of 40 W for 15 seconds, and (5) adjusting the applied power and pulse width to the thermal head so that the recording energy per unit area becomes 140 mJ / mm ² again. The image was printed and a cyan image was recorded. As a result, in addition to the yellow, magenta, and cyan color images, the recording portion where the yellow and magenta recordings overlap is red, the portion where magenta and cyan overlap is blue, and the portion where yellow and cyan overlap is green. , And the image portion where the recordings of yellow, magenta, and cyan overlapped developed black. The unrecorded area was grayish white. The optical reflection densities of the yellow, magenta, and cyan coloring portions were measured with a Macbeth RD918 densitometer. The shelf life (raw storage property) was evaluated by leaving the obtained multicolor heat-sensitive recording material in a thermo-hygrostat kept at 40 ° C. and a relative humidity of 90% for 24 hours, fixed, and fixed the optical reflection density of the background. Was measured.

Example 7 The procedure of Example 6 was repeated, except that the diazonium salt compound capsule solution described in Example 2 was used as the diazonium salt compound capsule solution used in the thermosensitive coloring layer (A). Thus, a multicolor heat-sensitive recording material was obtained. For the heat-sensitive recording material obtained above, the color development density and the density of the non-printed portion were measured in the same manner as in the heat recording of Example 6. Table 3 shows the results.

Table 3 (4) Color density of printed part Yellow magenta cyan color after fixing of non-printed part Density (yellow) ────────────────────────────── Example 6 0.80 1.00 1.10 0.12 Example 7 0.78 0.95 1.15 0.12──────────────────────────────

[0110]

The heat-responsive microcapsules of the present invention
High sensitivity to heat, high color development upon contact with couplers or color developers, and excellent properties when using diazo compounds as core material, showing excellent raw preservability (long shelf life) . Also, it has a sufficient color-forming property without reducing or using a heat sensitizer. Therefore, when the microcapsules are used for the heat-sensitive recording layer of a heat-sensitive recording material, a recording material having high sensitivity and color developing property can be obtained. Furthermore, when the above-mentioned microcapsules are used for the heat-sensitive recording layer, a multicolor heat-sensitive recording material having high sensitivity, excellent color reproducibility and excellent raw storability can be obtained.

Claims (5)

[Claims] 1. A microcapsule containing a diazo compound or an electron-donating dye precursor, wherein the capsule wall of the microcapsule has two active hydrogens in at least one kind of (A) molecule, And an adduct of a compound having at least one of a polyether chain, a polyester chain and a polysiloxane chain having an average molecular weight of 500 to 20,000 and a polyfunctional isocyanate having two or more isocyanate groups in the molecule (B). A thermoresponsive microcapsule comprising a polymer obtained by polymerization of an isocyanate compound. 2. The thermoresponsive microcapsule according to claim 1, wherein the compound (A) is a compound having a melting point of 40 to 180 ° C. 3. The thermoresponsive microcapsule according to claim 1, wherein the compound (A) is a polyethylene oxide or a polyester having hydroxyl groups at both ends. 4. A thermosensitive recording system comprising a support and a microcapsule and a coupler provided thereon and containing a diazo compound or a microcapsule containing an electron-donating dye precursor and a thermosensitive recording layer containing a color developer. Claims 1. A material, wherein the microcapsules are according to claim 1 or claim 2,
A heat-sensitive recording material, which is the heat-responsive microcapsule according to claim 3. 5. A transparent support, and a cyan, magenta and yellow heat-sensitive recording layer provided thereon, wherein each recording layer includes a microcapsule containing a diazo compound and a coupler, or an electron-donating dye precursor. A heat-responsive microcapsule according to claim 1, wherein the microcapsule contains a microcapsule and a color developer, wherein at least one of the microcapsules is a thermosensitive microcapsule according to claim 1. A multicolor heat-sensitive recording material, characterized in that: