JP2001191645A - Micro-capsule and heat-sensitive recording material and multi-color heat-sensitive recording material using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro-capsule which exhibits no color development by applying low energy and can realize sufficiently high density of color development by applying high energy and exhibits little blushing during storing and little yellowing with time by irradiation of light and in addition, can be inexpensively fed and a heat-sensitive recording material and a multi-color heat-sensitive recording material using it. SOLUTION: The capsule wall of the microcapsule comprises a polymer obtained by polymerizing an isocyanate compound comprizing an adduct of compounds shown by the below described general formulas (1) and/or (2) with a polyfunctional isocyanate with two isocyanate groups in the molecule. In the general formulas (1) and (2), R1-R4 are each a hydrogen, a 1-8C alkyl group, alkoxy group, aralkyl group, aryl group, etc., and 1 and m are each an integer of 0-3. However, 1+m is an integer of at most 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microcapsule, a heat-sensitive recording material using the microcapsule, and a multicolor heat-sensitive 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 heat-sensitive recording material other than the above, a so-called diazo-type heat-sensitive recording material utilizing a diazo compound has been studied. The diazo compound reacts with a phenol derivative or a compound having an active methylene group (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 thermosensitive recording materials, where a diazo compound and a coupler react with heat to form an image,
Thereafter, a light-fixing type thermosensitive recording material that can be fixed by light irradiation has been proposed (Koji Sato et al., "Journal of the Institute of Image Electronics Engineers of Japan," Vol. 11, No. 4, (1982), 290-29.
6, etc.).

However, a recording material using a diazo compound has a drawback that the storage life (shelf life) is short because the chemical activity is high and the diazo compound and the coupler gradually react even at a low temperature. . As one solution to this problem, a method has been proposed in which a diazo compound is encapsulated in microcapsules and isolated from couplers, water, and basic compounds (Masamasa Usami et al., "Journal of the Electrophotographic Society,
6, 2 (1987), 115-125).

[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 combination of a diazo compound and a thermosensitive coloring layer containing a coupler which reacts with the diazo compound when heated to form a color. Have been. 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 diazo compound in a microcapsule, these compounds are generally dissolved in an organic solvent (oil phase), and this is dissolved in 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, a diazo compound or an electron-donating dye precursor is first 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 accelerating the polymerization reaction to the aqueous phase or increasing the temperature of the emulsion to polymerize the 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).
No. 26189) As described above, polyvalent isocyanate compounds obtained by adding a polyhydric alcohol compound and a polyvalent isocyanate compound are well known.

Other examples using polyvalent isocyanate compounds include JP-A-61-169281, JP-A-5-168911, JP-A-8-230328 and JP-A-8-259.
486, Japanese Patent Application Laid-Open No. 7-883 discloses a combination example of a polyvalent isocyanate compound having three or more valences and a bifunctional isocyanate compound.
56, 7-185307, 7-204496, etc., various examples are described. Using these compounds, microcapsules containing various dye precursors have been developed and used for various heat-sensitive recording materials.

By the way, the color development start temperature and the amount of heat energy for starting color development required for the thermosensitive recording material differ depending on each recording system, and it is necessary to adjust to the desired color development start temperature and energy. For this purpose, microcapsules having different heat responsiveness have been developed by changing the degree of crosslinking and the glass transition temperature of the capsule wall by combining the various isocyanate compounds described above. For example,
In a multicolor heat-sensitive recording material, the microcapsules used for the lower layer do not cause any color development (that is, do not allow the substance to permeate) when the recording energy for coloring the upper layer is applied, and further cause the lower layer to develop color. When recording energy for recording (higher than the recording energy for coloring the upper layer) is applied, thermal responsiveness that causes rapid color development is required.

In order to solve such demands, there are, for example, means for increasing the wall thickness of the microcapsules and increasing the average particle diameter of the microcapsules. However, although the color sensitivity tends to decrease in these methods, even when high energy is applied, the density at which the color finally develops (referred to as the maximum color density) does not reach a sufficient value. However, there is a problem that a sufficiently high color density cannot be obtained because the formation of the color image does not proceed sufficiently effectively.

Although the use of the above-mentioned polyvalent isocyanate compounds has been widely studied, conventionally known polyvalent isocyanate compounds develop color even at a low applied energy (the color development is low. However, this results in a density at which the image quality is greatly reduced).

Therefore, improvements from isocyanate compounds forming capsule walls have been proposed, for example, polyvalent aromatic isocyanates such as a polymer of diphenylmethane diisocyanate and a formalin condensate of phenyl isocyanate ("MR200" manufactured by Nippon Polyurethane Industry Co., Ltd.). "etc)
Is commonly used. However, since this isocyanate is synthesized using a polycondensation reaction, the isocyanate compound itself is colored, and when used in a large amount, the coloring of the microcapsules themselves is conspicuous, and in the microcapsules obtained from this isocyanate, light irradiation causes There is a problem that yellow coloring occurs over time.

In order to solve these problems, a novel polyvalent isocyanate compound has been proposed in Japanese Patent Application No. Hei 9-25070. However, this isocyanate compound has a problem that the synthesis process is complicated and the cost of the compound is high.

In addition, when the microcapsules are stored under various conditions (high-temperature, high-humidity conditions, light-irradiation conditions, etc.), coloring (called fog) of the background occurs, and image quality and image visibility are reduced. Significantly lowers. This fog occurs, for example, during storage after production and before use. In the case of a thermosensitive recording material (a combination of an electron-donating dye precursor and a color developer) in which a fixing mechanism is not included in the dye formation reaction, the fog after printing is used. Some are generated when saving images. Since microcapsules generally used for heat-sensitive recording materials have thermal responsiveness, they cannot be said to sufficiently meet these requirements.

In particular, the multicolor heat-sensitive recording material is provided with a heat-sensitive recording layer capable of developing any of cyan, magenta, and yellow, and these may be printed by applying different heating temperatures. Therefore, it is required to control the thermal responsiveness more excellent than the heat-sensitive recording layer of a normal heat-sensitive recording material. Capsule walls obtained from conventional isocyanate compounds do not fully satisfy this requirement.

As described above, the heat-sensitive recording material does not form a color at all when low energy is applied, and develops a sufficient color density when a necessary energy is applied, and has a high storage stability. Simultaneously achieving the ability to supply materials at low cost has been very difficult.

[0019]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention can be suitably used for heat-sensitive recording materials and multicolor heat-sensitive recording materials, does not develop color at low energy application, can achieve a sufficiently high color density at high energy application, and at the time of storage It is an object of the present invention to provide a microcapsule which can be supplied at low cost with less fogging and yellowing over time due to light irradiation, and a heat-sensitive recording material and a multicolor heat-sensitive recording material using the same.

[0020]

The above object is achieved by the following means. That is, the present invention provides <1> a microcapsule containing a diazo compound or an electron-donating dye precursor, wherein the capsule wall of the microcapsule has at least (A) the following general formula (1) and / or
Or a polymer obtained by polymerization of an isocyanate compound containing an adduct of the compound represented by (2) and (B) a polyfunctional isocyanate having at least two isocyanate groups in a molecule. It is a capsule.

[0021]

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(In the general formulas (1) and (2), R ¹ , R ² ,
R ³ and R ⁴ are each independently hydrogen, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, an aralkyl group, an aryl group,
COOR ⁵ , —CONR ⁶ R ⁷ , a halogen, a cyano group, or a nitro group. R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen, an alkyl group having 1 to 8 carbon atoms, an aralkyl group, or an aryl group. l and m each independently represent an integer of 0 to 3. However, l + m is an integer of 3 or less. )

<2> A thermosensitive recording material comprising a support and a microcapsule and a coupler containing a diazo compound, or a microcapsule containing an electron-donating dye precursor and a thermosensitive recording layer containing a color developer. The microcapsules are the microcapsules according to the above <1>.

<3> Microcapsules and couplers having a support and two or more heat-sensitive recording layers capable of developing any of cyan, magenta and yellow, each of which contains a diazo compound, or A multicolor heat-sensitive recording material comprising a microcapsule containing an electron-donating dye precursor and a developer, wherein the microcapsules in at least one of the heat-sensitive recording layers are the microcapsules according to <1>. This is a multicolor heat-sensitive recording material characterized in that:

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Microcapsule) The microcapsule of the present invention contains a diazo compound or an electron-donating dye precursor, and the capsule wall is made of a polymer obtained by polymerization of an isocyanate compound.

In the microcapsule of the present invention, the capsule wall is composed of a polymer obtained by polymerization of an isocyanate compound, and the isocyanate compound contains at least an adduct of compound (A) and compound (B). Thereby, the microcapsules of the present invention do not develop color at low energy application, can realize a sufficiently high color density at high energy application, and have little fogging during storage, yellowing over time due to light irradiation, Further, supply can be performed at low cost.

The compound (A) has the following general formula (1) and / or
Or a compound represented by (2).

[0028]

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In the general formulas (1) and (2), R ¹ ,
R ² , R ³ , and R ⁴ each independently represent hydrogen, C 1-8
Alkyl group, an alkoxy group, an aralkyl group, an aryl ^{group, -COOR 5, -CONR 6 R 7} , halogen, a cyano group, a nitro group. R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen, an alkyl group having 1 to 8 carbon atoms, an aralkyl group, or an aryl group. l and m each independently represent an integer of 0 to 3. However, l + m is an integer of 3 or less.

In the general formulas (1) and (2), R ¹ ,
R ² , R ³ , and R ⁴ each independently represent hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl,
Cyclohexyl, methoxy, ethoxy, phenyl, benzyl, phenethyl and the like are preferred.
R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl,
Cyclohexyl, phenyl, benzyl, phenethyl and the like are preferred.

Specific examples of the compound represented by the general formula (1) include pyrogallol (that is, 1,2,3-trihydroxybenzene), 1,2,4-trihydroxybenzene,
Phloroglucin (that is, 1,3,5-trihydroxybenzene) and the like. The compound represented by the general formula (1) includes, for example, an alkyl group having 1 to 8 carbon atoms (eg, methyl group, ethyl group, propyl group, butyl group), an alkoxy group (eg, methoxy group, ethoxy group), and aralkyl. Group (benzyl group, phenethyl group, etc.), aryl group (phenyl group, etc.), COOR ³ group (carboxyl group, methoxycarbonyl group, etc.), CONR ⁴ R ⁵ (amide group, methylamide,
Dimethylamino group, etc.), halogen (chloro group, bromo group, etc.), cyano group, nitro group, etc., and combinations thereof.

Specific examples of the compound represented by the general formula (2) include 1,2,3-trihydroxycyclohexane,
1,2,4-trihydroxycyclohexane, 1,3
5-trihydroxycyclohexane and the like. Further, the compound represented by the general formula (2) may be substituted in the same manner as the compound represented by the general formula (1).

The compounds represented by the general formulas (1) and (2) include pyrogallol (namely, 1,2,3-trihydroxybenzene), 1,2,4-trihydroxybenzene, and phloroglucin (namely, 1,3,3). 5-trihydroxybenzene), 1,2,3-trihydroxycyclohexane, 1,2,4-trihydroxycyclohexane, 1,
3,5-Trihydroxycyclohexane is particularly preferred.

The compound (B) is a polyfunctional isocyanate having at least two isocyanate groups in the molecule. When the polyfunctional isocyanate in the compound (B) is bifunctional, for example, 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, norbornane diisocyanate, norbornene diisocyanate and the like. Further, addition products of these bifunctional isocyanates with bifunctional alcohols such as ethylene glycols and bisphenols, and phenols can also be used.

When the polyfunctional isocyanate in the compound (B) is trifunctional or higher, for example, the above-mentioned bifunctional isocyanate is used as a main raw material, and a trimer (buret or isocyanurate) thereof, trimethylolpropane or the like is used. Polyfunctional as an adduct of a polyol other than compound (A) and a bifunctional isocyanate compound, a formalin condensate of benzene isocyanate, a polymer of an isocyanate compound having a polymerizable group such as methacryloyloxyethyl isocyanate, lysine triisocyanate, etc. Is mentioned.

When the polyfunctional isocyanate in the compound (B) has three or more functional groups, in particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are mainly used, In addition to the isomer (buret or isocyanurate), a polyfunctional adduct with trimethylolpropane is preferred. These compounds are described in "Polyurethane Resin Handbook" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

As the polyfunctional isocyanate in the compound (B), when it has three or more functional groups, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-
Preference is given to 1,3-diisocyanate, adducts of trimethylolpropane with xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate, especially xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, Adducts of methylolpropane with xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate are particularly preferred.

The isocyanate compound contains at least an adduct of the compound (A) and the compound (B).
This adduct is preferably obtained by subjecting compound (A) and compound (B) to an addition reaction at a ratio of isocyanate group / OH group of 1.5 or more. The ratio of this isocyanate group / OH group is more preferably 1.5 to 6,
1.5 to 4 are particularly preferred. When the ratio of isocyanate group / OH group is less than 1.5, formation of microcapsules may be difficult due to a small number of isocyanate groups in the adduct. On the other hand, if the ratio of isocyanate group / OH group is too large, the degree of crosslinking of the obtained capsule wall becomes low, so that fog during storage tends to increase.

In the isocyanate compound, the adduct of the compound (A) and the compound (B) can be prepared by heating both compounds in an organic solvent having no active hydrogen while stirring (about 50 to 100 ° C.). ) Or by adding a catalyst such as stannous octylate, dibutyltin diacetate or the like at a relatively low temperature (about 40 to 70 ° C.), or by performing an addition reaction at room temperature. The adduct of compound (A) and compound (B) may be one type or a mixture of two or more types. Examples of the organic solvent include, for example, ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like.

The isocyanate compound may be used in combination with the above-mentioned adduct of the compound (A) and the compound (B) and other known polyfunctional isocyanates having two or more isocyanate groups for the purpose of adjusting the sensitivity and the like. it can. Examples of other polyfunctional isocyanates include, for example, the compounds exemplified as the compound (B). Other polyfunctional isocyanates include Japanese Patent Application No. 8-26.
No. 8721 and Japanese Patent Application No. 9-154699, compounds having one or two active hydrogens in the molecule and having a polyether chain or the like having an average molecular weight of 500 to 20,000 and a polyfunctional compound A reaction product with an isocyanate group is also included.

The other polyfunctional isocyanates may be used alone or in combination of two or more. However, in this case, the ratio between the compound (A) and the other polyfunctional isocyanate used in combination with the adduct of the compound (B) is 100/0 to 10/90.
The weight ratio is preferred, with 80/20 to 10/90 being particularly preferred.

In the microcapsule of the present invention, the capsule wall is made of a polymer obtained by the polymerization of the isocyanate compound. The polymerization of the isocyanate compound is performed, for example, with a compound having two or more active hydrogen atoms in the molecule. It is preferably performed in a reaction. Examples of the compound having such an active hydrogen atom include, for example, water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyamine compounds such as ethylenediamine and diethylenetriamine, and mixtures thereof. Can be Of these, it is particularly preferable to polymerize using water, but if necessary, water may be used in combination with the above-mentioned alcohols and amines. As a result, a capsule wall (polyurethane / polyurea wall) is formed.

More specifically, the microcapsule 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, phosphoric acid derivatives such as alkyl naphthalene, alkyl diphenyl ethane, alkyl diphenyl methane, diphenyl ethane alkyl adduct, alkyl biphenyl, chlorinated paraffin, tricresyl phosphate, and maleic acid such as di-2-ethylhexyl maleate Acid esters, adipic esters and the like can be mentioned. These may be used as a mixture of two or more.
When the solubility of the diazo compound or the electron-donating dye precursor in these hydrophobic solvents is not sufficient, a low-boiling solvent can be used in combination. As the low boiling organic solvent to be 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 to form a so-called coreless capsule in which only the diazo compound and the electron-donating dye precursor are present. Easy to do.

Depending on the type of the diazo compound, it may move to the aqueous phase side during the microencapsulation reaction, and in order to suppress this, an acid anion may be appropriately added to the water-soluble polymer solution in advance. Examples of the acid anion include PF ⁶⁻ , B (−Ph) ⁴ [Ph is a phenyl group], Z
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).

As the compound having active hydrogen used for the polymerization of the isocyanate compound for forming the microcapsule wall at the time of microencapsulation, water is generally used, but the polyol is used in a core organic solvent or a dispersion medium. Can be used as a compound having active hydrogen (one of the raw materials of the microcapsule wall). 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 preferred.

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 addition amount is 0.1 to 5% by weight, especially 0.5 to 2% by weight based on the weight of the oil phase.
Is preferred. In general, surfactants used for emulsification and dispersion are considered to be excellent surfactants having a relatively long-chain hydrophobic group. “Handbook of Surfactants” (Nishiichiro et al., Published by Sangyo Tosho (1980)), alkyl Alkali metal salts such as sulfonic acid and alkylbenzene sulfonic acid can be used.

Compounds such as a formalin condensate of an aromatic sulfonate and a formalin condensate of an aromatic carboxylate can also be used as a surfactant (emulsifier). Specifically, a compound represented by the following general formula (A) is preferably mentioned. This compound is disclosed in Japanese Patent Application No. 5-837.
No. 21. In addition, compounds of alkyl glucoside compounds can be used in the same manner. Specifically, a compound represented by the following formula (B) is preferably exemplified.

[0049]

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In the general formula (A), R represents 1 carbon atom
The ~ 4 alkyl group, X is SO ^3- or COO ^- and, M is a sodium atom or potassium atom and q is 1-2,
Represents an integer of 0.

[0051]

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In the general formula (B), R represents 4 carbon atoms.
And q represents an integer of 0 to 2;

In the microcapsules of the present invention, any of the surfactants may be used alone or in combination of two or more.

A solution comprising a diazo compound (or an electron-donating dye precursor), a solvent having a high boiling point and the like, and an isocyanate compound (including an adduct of compound (A) and compound (B))
(Oil phase) is added to an aqueous solution (aqueous phase) comprising a surfactant and a water-soluble polymer. At that time, while stirring the aqueous solution with a high shear stirring device such as a homogenizer,
It is emulsified and dispersed by adding. 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 the diazo compound, a coupling reaction 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 diazo 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 osmosis, etc. Methods such as 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 JP-A-61-2968.
No. 8 publication.

In the microcapsules of the present invention, the diazo compound or the electron-donating dye precursor is dissolved in a high-boiling solvent and encapsulated in the microcapsules as described above. The diazo compound and the electron donating dye precursor will be described in detail together with the heat-sensitive recording material of the present invention.

(Thermal Recording Material) The thermal recording material of the present invention comprises a support and a microcapsule and a coupler containing a diazo compound, or a microcapsule containing a precursor of an electron-donating dye and a developer containing a developer. A recording layer, and the microcapsules are the microcapsules of the present invention. By using the microcapsules of the present invention as the microcapsules, the heat-sensitive recording material of the present invention does not form a color when low energy is applied, and can realize a sufficiently high color density when high energy is applied. Fog and yellowing over time due to light irradiation are reduced.

The heat-sensitive recording layer is formed by coating a microcapsule containing a diazo compound and a preparation liquid containing a coupler and, if necessary, other additives at an appropriate ratio.
Alternatively, a coating solution in which a microcapsule containing an electron-donating dye precursor and a developer (electron-accepting compound) and, if necessary, a preparation solution of other additives are mixed at an appropriate ratio is supported. It can be formed by coating on the body. Hereinafter, each material will be described.

As the diazo compound, the following general formula (3)
Compounds represented by (6) to (6) are preferred.

[0060]

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[0061]

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[0062]

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[0063]

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In the general formula (3), Ar represents an aryl group, and R ¹¹ and R ¹² each represent a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted alkyl group having 6 to 20 carbon atoms. Represents a substituted aryl group. R ¹¹ and R ¹² may be the same or different. X ^- represents an acid anion.

In the general formula (4), R ¹⁴ , R ¹⁵ , R ¹⁶
Represents a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. R ¹⁴ , R ¹⁵ and R ¹⁶ may be the same or different. Y represents a hydrogen atom, or an OR ^17. R ¹⁷ represents a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. X ^- represents an acid anion.

In the general formula (5), Z represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, or OR
Represents ¹⁹ . R ¹⁸ and R ¹⁹ each represent a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. R ¹⁸ and R ¹⁹ may be the same or different. X ^- represents an acid anion.

In the general formulas (3) to (5), examples of the acid anion represented by X ⁻ include a polyfluoroalkyl carboxylate ion having 1 to 9 carbon atoms, an alkyl sulfonate ion having 1 to 9 carbon atoms, and tetrafluoride. Examples include boron fluoride, tetraphenylboron, hexafluorophosphate ion, aromatic carboxylate ion, and aromatic sulfonate ion.

In the general formula (6), R ¹⁹ , R ²⁰ ,
R ²¹ and R ²² each independently represent a hydrogen atom, an alkyl group,
Aryl group, -OR ²³ , -SR ²⁴ , -NR ²⁵ R ²⁶ , -C
OR ^{28 represents} a halogen atom, —SONR ²⁵ R ²⁶ . Here, R ²³ and R ²⁴ represent a hydrogen atom, an alkyl group, an aryl group, and an acyl group, respectively, and R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkylsulfonyl group, and an aryl group. Represents a sulfonyl group, and further, R ²⁵ and R ²⁶ are linked to each other to form -0-, -S
—, —SO ₂ —, or —NR ²⁷ — represents an alkylene group which may contain, where R ²⁷ is a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, an aryl Represents an oxycarbonyl group, and R ²⁸ represents a hydrogen atom, a hydroxyl group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group,
Represents NR ²⁵ R ²⁶ . Here, R ²⁵ and R ²⁶ have the same meanings as described above. Also, A is -CO -, - SO ₂ -, B stands represents -SO ₂ R ^29, the -POR ³⁰ R ^31. Here, R ²⁹ represents an alkyl group, an aryl group, a heterocyclic group, -N
R ²⁵ represents R ²⁶ . R ³⁰ and R ³¹ each independently represent an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. R ²⁵ and R ²⁶ have the same meanings as described above.

Hereinafter, specific examples of the diazo compounds represented by the general formulas (3) to (6) are shown, but the present invention is not limited thereto.

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The diazo compounds represented by formulas (3) to (6) can be produced by a known method. That is, it is obtained by diazotizing the corresponding aniline using sodium nitrite, nitrosylsulfuric acid, isoamyl nitrite or the like in an acidic solvent.

The diazo compounds represented by the general formulas (3) to (6) may be used alone or in combination of two or more. Further, the diazo compounds represented by the general formulas (3) to (6) may be used in combination with the existing diazo compounds according to various purposes such as hue preparation. For existing diazo compounds, please refer to The Focal Press Lo.
ndon and New York "Photos
intensivediazo Compounds a
nd their uses, pp. 57-86 (196
4) etc.

For stabilizing the diazo compound, zinc chloride,
The diazo compound can be stabilized by forming a complex compound using cadmium chloride, tin chloride or the like.

As the coupler (not encapsulated in the microcapsule), any compound can be used as long as it can form a dye by coupling with a diazo compound in a basic atmosphere and / or a neutral atmosphere. All so-called 4-equivalent couplers for silver halide photographic materials can be used as couplers. These can be selected according to the desired hue.

For example, there are a so-called active methylene compound having a methylene group next to a carbonyl group, a phenol derivative, a naphthol derivative, and the like. Specific examples thereof include the following, which are used in a range meeting the object of the present invention.

As the coupler, a compound represented by the following general formula (7) is particularly preferred.

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In the general formula (7), the electron-withdrawing groups represented by E ¹ and E ² are substituents having a positive Hammett σ value, which may be the same or different. Preferred are an acyl group, an alkoxycarbonyl group, a carbamoyl group, a cyano group, a nitro group, an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic group, a phosphono group and the like. Acetyl, propionyl, pivaloyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, 1-methylcyclopropylcarbonyl, 1
Acyl groups such as -ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group, and thenoyl group, methoxycarbonyl group, ethoxycarbonyl group, 2-methoxyethoxycarbonyl group, and 4-methoxyphenoxy An oxycarbonyl group such as a carbonyl group, a carbamoyl group, N, N-
Dimethylcarbamoyl group, N, N-diethylcarbamoyl group, N-phenylcarbamoyl group, N- [2,4-bis (pentyloxy) phenyl] carbamoyl group, N-
[2,4-bis (octyloxy) phenyl] carbamoyl group, carbamoyl group such as morpholinocarbonyl group,
Alkylsulfonyl or arylsulfonyl such as methanesulfonyl, benzenesulfonyl, and toluenesulfonyl, phosphono such as diethylphosphono, benzoxazol-2-yl, and benzothiazole-2-
Yl group, 3,4-dihydroquinazolin-4-one-2-
Yl group, 3,4-dihydroquinazoline-4-sulfone-
A heterocyclic group such as a 2-yl group, a nitro group, an imino group, and a cyano group are preferred.

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

Specific examples of the compound represented by the general formula (7) include resorcin, phloroglucin, 2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene-
Sodium 6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 2-hydroxy-3
-Sodium naphthalene sulfonate, 2-hydroxy-
3-naphthalenesulfonic acid anilide, 2-hydroxy-
3-naphthalenesulfonic acid morpholinopropylamide,
2-hydroxy-3-naphthalenesulfonic acid-2-ethylhexyloxypropylamide, 2-hydroxy-3
-Naphthalenesulfonic acid-2-ethylhexylamide,
5-acetamido-1-naphthol, 1-hydroxy-
Sodium 8-acetamidonaphthalene-3,6-disulfonic acid, 1-hydroxy-8-acetamidonaphthalene-3,6-disulfonic acid dianilide, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2 -Hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid anilide, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclopentanedione, 5- (2-n
-Tetradecyloxyphenyl) -1,3-cyclohexanedione, 5-phenyl-4-methoxycarbonyl-
1,3-cyclohexanedione, 5- (2,5-di-n
-Octyloxyphenyl) -1,3-cyclohexanedione, N, N′-dicyclohexylbarbituric acid,
N, N'-di-n-dodecylbarbituric acid, Nn-
Octyl-N'-n-octadecylbarbituric acid, N
-Phenyl-N '-(2,5-di-n-octyloxyphenyl) barbituric acid, N, N'-bis (octadecyloxycarbonylmethyl) barbituric acid,

1-phenyl-3-methyl-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-anilino-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3 -Benzamide-5-pyrazolone, 6
-Hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) -2-pyridone, 2,4-bis- (benzoylacetamido) toluene, 1,3-bis- (pivaloylacetoamidomethyl) benzene, Benzoylacetonitrile, thenoylacetonitrile, acetoacetanilide, benzoylacetanilide, pivaloylacetanilide, 2-chloro-5- (Nn-butylsulfamoyl) -1-pivaloylacetamidebenzene, 1-
(2-ethylhexyloxypropyl) -3-cyano-
4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (dodecyloxypropyl) -3-
Acetyl-4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (4-n-octyloxyphenyl) -3-tert-butyl-5-aminopyrazole and the like.

For the details of the coupler, see JP-A-4-24-2
01483, JP-A-7-223267, JP-A-7-223
223368, JP-A-7-323660, Japanese Patent Application No. 5
-278608, Japanese Patent Application No. 5-297024, Japanese Patent Application No. 6-18669, Japanese Patent Application No. 6-18670, Japanese Patent Application No. 7
-316280, Japanese Patent Application No.8-027095, Japanese Patent Application No.8-027096, Japanese Patent Application No.8-030799, Japanese Patent Application No.8-12610, Japanese Patent Application No.8-132394, Japanese Patent Application No.8-358755. And Japanese Patent Application Nos. 8-358756 and 9-069990.

Specific examples of the coupler represented by the general formula (7) are shown below, but the present invention is not limited thereto.

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Examples of the electron-donating dye precursor include a triarylmethane compound, a diphenylmethane compound, a thiazine compound, a xanthene compound, and a spiropyran compound. In particular, a triarylmethane compound and a xanthene compound are preferred. High color density is useful.

Specific examples of the electron donating dye precursor include:
3,3-bis (p-dimethylaminophenyl) -6 dimethylaminophthalide (that is, 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, 3- (o-methyl-p-diethylaminophenyl) -3- (1'-ethyl-2-methylindol-3-yl) Phthalide, 4,4'-bis (dimethylamino) benzhydrin benzyl ether,
N-halophenyl leuco auramine, N-2,4,5-
Trichlorophenylleuco auramine, rhodamine-B
-Anilinolactam, 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 developer (electron-accepting compound (not encapsulated in microcapsules)) include phenol derivatives,
Salicylic acid derivatives, hydroxybenzoic acid esters and the like. 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-hydroxy Phenyl)
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 salts, 3,5-di (tert-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 Can be mentioned. In the present invention,
These electron accepting compounds can be used in combination of two or more at any ratio.

In the heat-sensitive recording layer, a reaction between a diazo compound and a coupler or a reaction between an electron-donating dye precursor and a developer together with a coupler or a developer (electron accepting compound) is carried out. It is preferable to add a sensitizer. As the sensitizer, a low-melting organic compound having an aromatic group and a polar group in the molecule is preferable. Specific examples thereof include benzyl p-benzyloxybenzoate,
α-naphthyl benzyl ether, β-naphthyl benzyl 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-ethylhexyloxy) 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.

When a combination of a microcapsule encapsulating a diazo compound and a coupler is used in the heat-sensitive recording layer, a base finely dispersed by emulsification and / or solid dispersion together with the coupler for the purpose of accelerating the dye formation reaction. It is common to add a toxic substance. Examples of the basic substance include an inorganic or organic basic compound, and a compound that releases 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,
4'-dithiomorpholine, morpholinium trichloroacetate, 2-aminobenzothiazole, and 2-benzoylhydrazinobenzothiazole. These may be used in combination of two or more.

When a combination of a microcapsule containing a diazo compound and a coupler is used in the heat-sensitive recording layer, a color-forming aid is added together with the coupler in addition to the above-mentioned basic substance in order to promote a color-forming reaction. be able to. Coloring aids are used to increase the color density during heating recording,
Alternatively, it is a substance that lowers the minimum color development temperature.Diazo compounds, basic substances, couplers, etc. react by lowering the melting point of couplers, basic substances, diazo compounds, etc., or lowering the softening point of the capsule wall. This is to create a situation that is easy to do. As a color-forming aid, for example, phenol derivatives, naphthol derivatives, alkoxy-substituted benzenes, alkoxy-substituted naphthalenes, aromatic ethers, thioethers, esters, amides in the color-forming layer so that thermal printing is performed quickly and completely with low energy. , Ureido, urethane, sulfonamide compound hydroxy compound, and the like.

The heat-sensitive recording layer may be used together with a coupler or a color developer (electron accepting compound) to improve the fastness of the thermochromic image to light and heat, or to prevent yellowing due to light in the unprinted portion after fixing. For the purpose of reduction, it is preferable to use the following known antioxidants and the like. Regarding the above-mentioned antioxidants, for example, European Patent Publication No. 2,237,939, Japanese Patent Publication No. 309401, Japanese Patent Publication No. 309402, Japanese Patent Publication No. 310510, Japanese Patent Publication No. 310552, Japanese Patent Publication No. 559416, and German Publication No. Patent No. 343
5443, JP-A-54-48535, 6
JP-A-2-262407, JP-A-63-113536, JP-A-63-163351, JP-A-2-2626
54, JP-A-2-71262, JP-A-3-
JP-A-121449, JP-A-5-61166, JP-A-5-119449, U.S. Pat.
262, U.S. Pat. No. 4,980,275, and the like.

It is also effective to add, to the heat-sensitive recording layer, various known additives already used in heat-sensitive recording materials and pressure-sensitive recording materials, together with a coupler or a color developer (electron-accepting compound). Specific examples of these various additives include JP-A-60-107384 and JP-A-60-107384.
7383, 60-125470, 60
-125471, 60-125472,
JP-A-60-287485, JP-A-60-287486, JP-A-60-287487, and JP-A-60-2874
Nos. 88, 61-160287, 61-1
Nos. 85483, 61-211079, 6
2-146678, 62-146680, 62-146679, and 62-28888.
No. 5, JP-A-63-051174, JP-A-63-89
877, 63-88380, 63-0
Nos. 88381, 63-203372, 6
JP-A-3-22489, JP-A-63-251282, JP-A-63-267594, JP-A-63-18248.
No. 4, JP-A-1-239282, 4-29
Nos. 1685, 4-291684, 5-1
Nos. 88687, 5-188686, 5-
Compounds described in JP-A-110490, JP-A-5-1108437, JP-A-5-170361, JP-B-48-043294 and JP-A-48-033212 can be exemplified.

Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2 -Dihydroquinoline, 6-ethoxy-1-
Phenyl-2,2,4-trimethyl-1,2,3,4-
Tetrahydroquinoline, 6-ethoxy-1-octyl-
2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, nickel cyclohexanoate, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2- Ethyl hexane, 2
-Methyl-4-methoxy-diphenylamine, 1-methyl-2-phenylindole and the like.

The addition amount of these antioxidants and various additives is 0.05 to 100 parts by weight based on 1 part by weight of the diazo compound.
It is preferable that the ratio is part by weight, particularly 0.2 to 30 parts by weight.
It is preferably in parts by weight. Such known antioxidants and various additives may be used in a microcapsule together with a diazo compound, or may be used together with a coupler, a basic substance, and other color-forming auxiliaries as a solid dispersion or an appropriate emulsification. It can be used in the form of an emulsion together with the auxiliary agent, or both. It goes without saying that antioxidants and various additives can be used alone or in combination. Further, it can be added to or present in the protective layer.

These antioxidants and various additives need not be added to the same layer. When a plurality of these antioxidants and various additives are used in combination, structurally classify them as anilines, alkoxybenzenes, hindered phenols, hindered amines, hydroquinone derivatives, phosphorus compounds, and sulfur compounds. Alternatively, different structures may be combined, or a plurality of same structures may be combined.

In the heat-sensitive recording layer, together with a coupler or a developer (electron-accepting compound), a free radical generator (such as a photopolymerizable composition) used in a photopolymerizable composition or the like for the purpose of reducing yellowing of the background after recording. A compound that generates free radicals upon irradiation with light). Examples of the free radical generator include aromatic ketones, quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, acyl oxime esters, and the like. The amount to be added is preferably 0.01 to 5 parts by weight of a free radical generator per 1 part by weight of the diazo compound.

In the heat-sensitive recording layer, a polymerizable compound having an ethylenically unsaturated bond (hereinafter, referred to as a compound or a compound having an ethylenically unsaturated bond) together with a coupler or a color developer (electron-accepting compound) for the purpose of reducing yellowing.
Vinyl monomers). A vinyl monomer is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and has a chemical form of a monomer or prepolymer. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, and amides of unsaturated carboxylic acids and aliphatic polyamine compounds. The vinyl monomer is used in an amount of 0.2 to 20 parts by weight based on 1 part by weight of the diazo compound. The free radical generator and the vinyl monomer can be used in a microcapsule together with a diazo compound or an electron-contributing dye precursor.

To the heat-sensitive recording layer, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like can be added as an acid stabilizer together with a coupler or a color developer (electron accepting compound).

In the heat-sensitive recording layer, a known water-soluble polymer compound or latex can be used as a binder used together with a coupler or a color developer (electron accepting compound). Examples of the water-soluble polymer compound include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivatives, casein, gum arabic, gelatin, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, and polyvinyl alcohol. , Epichlorohydrin-modified polyamide, isobutylene-maleic salicylic anhydride copolymer, polyacrylic acid, polyacrylamide, and the like, and modified products thereof. Examples of the latex include styrene-butadiene rubber latex and methyl acrylate-butadiene rubber. Latex, vinyl acetate emulsion and the like.

In the heat-sensitive recording layer, known pigments, whether organic or inorganic, can be used as a pigment to be used together with a coupler or a color developer (electron accepting compound).
More specifically, kaolin, calcined kaolin, talc, lauric stone, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone, silica, magnesium carbonate , Titanium oxide, alumina, barium carbonate,
Examples include barium sulfate, mica, microballoons, urea-formalin filler, polyester particles, cellulose filler and the like.

In the heat-sensitive recording layer, a known wax, an antistatic agent, a defoaming agent, a conductive agent, a fluorescent dye, a surfactant, an ultraviolet ray, if necessary, together with a coupler or a color developer (electron accepting compound). Various additives such as an absorbent and a precursor thereof can also be added.

In the heat-sensitive recording layer, a preparation liquid such as a coupler or a color developer (electron accepting compound) and, if necessary, various additives (sensitizers, basic substances, etc.) described above is prepared by using these materials. The mixture may be added as appropriate, and then separately emulsified or dispersed to form fine particles after being dispersed or solid-dispersed. In the method of emulsifying and dispersing, it is preferable that these compounds are dissolved in an organic solvent, and an aqueous solution of a water-soluble polymer is added while stirring with a homogenizer or the like. As a method of solid dispersion, it is preferable that these materials are put into an aqueous solution of a water-soluble polymer and finely divided using a known dispersing means such as a ball mill.
In order to promote fine particles by emulsification dispersion or solid dispersion, it is preferable to use the above-mentioned hydrophobic organic solvent, surfactant and water-soluble polymer. In addition, when the fine particles are formed, it is preferable to obtain a particle diameter that satisfies the properties required for a multicolor heat-sensitive recording material such as heat sensitivity, storage stability, transparency of the recording layer, suitability for production, and a method for producing the same. .

In the heat-sensitive recording layer, the amount of the coupler to be added is 1 to 10 mol, preferably 2 to 6 mol, per 1 mol of the diazo compound. The amount of basic substance added is
Depending on the basic strength, it is suitably 0.5 to 5 mol per 1 mol of the diazo compound. The amount of the developer added is 0.5 to 30 mol per 1 mol of the electron-donating dye precursor,
It is preferably 1 to 20 mol, more preferably 3 to 15 mol. The amount of the heat sensitizer to be added is generally 0.1 to 1 mol per mol of the diazo compound or the electron donating dye precursor.
20 mol, preferably 0.5 to 10 mol, is suitable.

The heat-sensitive recording layer is prepared by mixing a microcapsule containing a diazo compound or an electron-donating dye precursor with a preparation solution containing a coupler or a developer and, if necessary, various additives described above. Prepare a coating solution, bar coating, blade coating on a support such as paper or synthetic resin film,
It is preferable that the coating is performed by applying and drying by a coating method such as air knife coating, gravure coating, roll coating coating, spray coating, dip coating, curtain coating or the like. The heat-sensitive recording layer is preferably provided so as to have a solid content of 2.5 to 30 g / m ² .

In the heat-sensitive recording material of the present invention, microcapsules, couplers, developers, and other basic substances containing a diazo compound or an electron-donating dye precursor may be contained in the same layer. It is also possible to adopt a laminated type structure included in a layer. Further, after providing an intermediate layer as described in Japanese Patent Application No. 59-177669 on a support, a heat-sensitive recording layer can be applied.

In the heat-sensitive recording material of the present invention, in the case of a single layer structure (single color), the same heat-sensitive recording layer is used in combination with the microcapsules of the present invention and other conventionally known microcapsules for the purpose of sensitivity adjustment and the like. You can also. In this case, the microcapsule of the present invention contains 20
It is suitable to use them together in an amount of at least 30% by weight, more preferably at least 40% by weight, more preferably at least 40% by weight.

The heat-sensitive recording material of the present invention may be provided with a protective layer on the surface of the heat-sensitive recording layer, if necessary. Two or more protective layers may be laminated as necessary. Materials used for the protective layer include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose,
Hydroxymethyl cellulose, gelatin, gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative Water-soluble polymer compounds such as polyvinylpyrrolidone, sodium polystyrenesulfonate and sodium alginate; and latexes such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. . The water-soluble polymer compound of the protective layer can be cross-linked to further improve the storage stability, and a known cross-linking agent can be used as the cross-linking agent. Specifically, N-methylol urea, N-methylol melamine, urea
Examples include water-soluble initial condensates such as formalin, dialdehyde compounds such as glyoxal and glutaraldehyde, inorganic crosslinking agents such as boric acid and borax, and polyamide epichlorohydrin. For the protective layer, known pigments, metal soaps, waxes, surfactants and the like can be further used.
The coating amount of the protective layer is preferably 0.2-5 g / m ^2, more preferably 0.5 to 2 g / m ^2. Further, the film thickness is preferably from 0.2 to 5 μm, particularly preferably from 0.5 to 2 μm.

When a protective layer is used in the heat-sensitive recording material of the present invention, the protective layer may contain a known ultraviolet absorbent or a precursor thereof.

In the case where a heat-sensitive recording layer using a diazo compound is provided in the heat-sensitive recording material of the present invention, the light transmittance adjusting layer in which the light transmittance in the wavelength region where light is fixed to the heat-sensitive recording layer decreases after fixing on the support. Is preferably provided, and a protective layer is further provided thereon.

In the heat-sensitive recording material of the present invention, the light transmittance adjusting layer contains a component functioning as a precursor of an ultraviolet absorber, and is used as an ultraviolet absorber before irradiation with light having a wavelength necessary for fixing. Since it does not function, the light transmittance is high, and when fixing the heat-sensitive recording layer, it sufficiently transmits the wavelength in the area necessary for fixing, and the transmittance of visible light is high, which hinders the fixing of the heat-sensitive recording layer. Absent.

The precursor of the ultraviolet absorber may function as an ultraviolet absorber by reacting with light or heat after light irradiation of a wavelength necessary for fixing the heat-sensitive recording layer by light irradiation is completed. Most of the light having a wavelength in the ultraviolet region is absorbed by the ultraviolet absorbent, the transmittance is reduced, and the light resistance of the heat-sensitive recording material is improved. The transmittance does not substantially change.

In the heat-sensitive recording material of the present invention, at least one light transmittance adjusting layer can be provided in the heat-sensitive recording material, and is most preferably formed between the heat-sensitive recording layer and the protective layer. Alternatively, the light transmittance adjusting layer may be used also as the protective layer. The characteristics of the light transmittance adjusting layer can be arbitrarily selected according to the characteristics of the heat-sensitive recording layer.

In the heat-sensitive recording material of the present invention, as the support, any paper support used for ordinary pressure-sensitive paper, heat-sensitive paper, dry or wet diazo copy paper, etc. can be used. , Neutral paper, coated paper, plastic film laminated paper, synthetic paper, plastic film and the like can be used. A back coat layer may be provided to correct the curl balance of the support or to improve the chemical resistance from the back surface, or to form a label by combining release paper with an adhesive layer on the back surface. You may. This back coat layer can be provided in the same manner as the above protective layer.

In the heat-sensitive recording material of the present invention, when the recording surface is heated with a thermal head or the like, the capsule wall of the microcapsules is softened, and the coupler and the base compound outside the capsule enter the capsule to form a color. After color development, irradiation with light having an absorption wavelength of the diazo compound causes decomposition of the diazo compound and loss of reactivity with the coupler, thereby fixing an image.

[0124] As the fixing light source, various fluorescent lamps,
A xenon lamp, a mercury lamp or the like is used, and it is preferable that the emission spectrum substantially coincides with the absorption spectrum of the diazo compound used in the heat-sensitive recording material because it can be efficiently fixed. In the present invention, the emission center wavelength is 360 to 440.
nm fixing light sources are particularly preferred.

(Multicolor heat-sensitive recording material) The multicolor heat-sensitive recording material of the present invention has a support, and two or more heat-sensitive recording layers capable of coloring in any of cyan, magenta and yellow.
Each heat-sensitive recording layer contains a microcapsule and a coupler containing a diazo compound, or a microcapsule containing a electron-donating dye precursor and a color developer, and the microcapsules in at least one layer of the heat-sensitive recording layer are the same as those described above. It is a microcapsule of the invention. By using the microcapsules of the present invention as the microcapsules, the multicolor thermosensitive recording material of the present invention does not develop color when low energy is applied, and can realize a sufficiently high color density when high energy is applied, and can be stored. Fog at the time and yellowing over time due to light irradiation are reduced. In addition, each thermosensitive recording layer, support,
Other layers such as a protective layer and a light transmittance adjusting layer can be prepared in the same manner as in the heat-sensitive recording material of the present invention.

In the multicolor heat-sensitive recording material of the present invention, the microcapsules of the present invention do not form a color when a low energy is applied, and from the viewpoint that a sufficiently high color density can be realized when a high energy is applied, the microcapsules have the highest temperature (high energy). Is preferably contained in the heat-sensitive recording layer (generally, the lowermost layer) to be colored by the application of a color. Thereby, at the time of coloring of the heat-sensitive recording layer for low-temperature coloring (low energy application), the heat-sensitive recording layer containing the microcapsules of the present invention does not develop color, and a pure color-developed image of the heat-sensitive recording layer for coloring at low temperature can be obtained. Image quality is improved.

The multicolor heat-sensitive recording material of the present invention can be produced by using a photodegradable diazo compound having different photodecomposition wavelengths for two or more heat-sensitive recording layers.
By changing the hue of two or more thermosensitive recording layers, a full-color multicolor thermosensitive recording material is obtained. For example, a full-color image can be recorded by selecting the coloring hues of the respective heat-sensitive recording layers so as to be three primary colors in subtractive color mixing, yellow, magenta, and cyan. In this case, directly on the support surface
The color-forming mechanism of the heat-sensitive recording layer laminated (the lowermost layer of the heat-sensitive recording layer) comprises a diazo color-forming system comprising a diazo compound and a coupler which reacts with the diazo compound to form a color, and comprises an electron-donating dye and a developer. Any of a leuco coloring system, a base coloring system that forms a base upon contact with a basic compound, a chelate coloring system, and a coloring system that reacts with a nucleophile to cause a desorption reaction to form a color may be used. It is preferable to provide two heat-sensitive recording layers each containing a diazo compound having a different maximum absorption wavelength and a coupler which reacts with the diazo compound to give a color, and a light transmittance adjusting layer and a protective layer are sequentially provided on this layer.

In the multicolor heat-sensitive recording material of the present invention, as the heat-sensitive recording layer, a heat-sensitive recording layer containing a diazo compound having a maximum absorption wavelength of 360 ± 20 nm and a coupler which reacts with the diazo compound and forms a color is used. Wavelength 400 ± 20
It is preferable to contain a thermosensitive recording layer containing a diazo compound having a diameter of nm and a coupler which reacts with the diazo compound to form a color.

The multicolor heat-sensitive recording material of the present invention includes a heat-sensitive recording layer containing an electron-donating dye and an electron-accepting compound on a support, a diazo compound having a maximum absorption wavelength of 360 ± 20 nm, and a diazo compound. A heat-sensitive recording layer containing a coupler which reacts with and forms a color, and a maximum absorption wavelength of 400 ± 20.
a thermosensitive recording layer containing a diazo compound having a diameter of nm and a coupler which reacts with the diazo compound to form a color, and
It is preferable that a light transmittance adjusting layer is provided on this layer.

The multicolor heat-sensitive recording material of the present invention includes, on a support, a heat-sensitive recording layer containing a diazo compound having a maximum absorption wavelength of 310 ± 20 nm or less, and a coupler capable of performing a color reaction with the diazo compound. Maximum absorption wavelength 360 ± 20nm
A thermosensitive recording layer containing a diazo compound and a coupler which reacts with the diazo compound to form a color.
It is preferable that a thermosensitive recording layer containing a diazo compound having a diameter of 0 ± 20 nm and a coupler which reacts with the diazo compound and forms a color is sequentially provided, and a light transmittance adjusting layer is provided on this layer.

In the multicolor heat-sensitive recording material of the present invention, since a plurality of heat-sensitive recording layers are laminated, an intermediate layer may be provided between the heat-sensitive recording layers for the purpose of preventing color mixing between the heat-sensitive recording layers. This intermediate layer is made of a water-soluble polymer compound such as gelatin, phthalated gelatin, polyvinyl alcohol, and polyvinylpyrrolidone, and may appropriately contain various additives.

The multicolor heat-sensitive recording material and the recording method of the present invention will be described in more detail. First, the outermost thermosensitive layer containing a diazo 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 diazo compound contained in the thermosensitive layer is obtained. Irradiates the entire surface with a light source that emits light of the above formula to photodecompose the diazo compound remaining in the uppermost thermosensitive layer.

Next, a second heat-sensitive layer (second layer) containing a diazo compound having a higher energy than the previous one and having a light absorption wavelength range different from the absorption wavelength range of the diazo compound contained in the first layer. (2) heat-sensitive recording layer, usually a magenta color-forming layer), and the entire surface is again irradiated with a light source that emits light in the absorption wavelength range of the diazo compound.
The diazo compound remaining in the second heating layer is photolyzed. 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 be transparent heat-sensitive layers, since 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 recording 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 diazo 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 a multicolor heat-sensitive recording material, the third heat-sensitive recording layer can be formed by combining an appropriate diazo compound and a coupler.

Hereinafter, the thermosensitive recording material and the multicolor thermosensitive recording material of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the thermosensitive recording material of the present invention. The thermal recording material shown in FIG. 1 has a support 11, a thermal recording layer 12, and a protective layer 13. Thermal recording layer 12
Contains a coupler and a microcapsule containing a diazo compound A which reacts with the coupler to form an azo dye. When heat is applied to the heat-sensitive recording layer from the protective layer 13 by a thermal head or the like, the coupler outside the capsule penetrates into the capsule (and / or the diazo compound A inside the capsule is released outside the capsule), and And the diazo compound A undergo a coupling reaction. The resulting azo dye has the color of the heat-donating portion, and a single-color image is formed. After image formation, it is preferable that the diazo compound A in the unprinted area is decomposed by light irradiation to fix the image, from the viewpoint of image storage stability. For fixing the image, a fixing process may be performed using a light source corresponding to the decomposition wavelength of the diazo compound A.

FIG. 2 is a schematic sectional view showing an example of the multicolor heat-sensitive recording material of the present invention. The multicolor thermosensitive recording material shown in FIG. 2 is a subtractive color mixture system having a support 21 and three thermosensitive recording layers of a yellow layer 22, a cyan layer 23, and a magenta layer 24. An intermediate layer 25 is provided between the yellow layer 22 and the cyan layer 23, and an intermediate layer 26 is provided between the cyan layer 23 and the magenta layer 24, so that the diffusion of the coupler or the like between the layers is suppressed. ing. An ultraviolet transmittance adjusting layer 27 is provided on the magenta layer 24, and a protective layer 28 is further provided thereon to prevent the heat-sensitive recording layer such as the magenta layer 24 from being physically and / or chemically deteriorated. are doing. The magenta layer 24 contains a coupler M and a diazo compound M, and the yellow layer 22 contains a coupler Y and a diazo compound Y. The cyan layer 23 contains a coupler C and a diazo compound C. Resolution wavelength λ of each of diazo compound M, diazo compound C, and diazo compound Y
The relationship with 1, λ2, λ3 is λ3 <λ2 <λ1. The diazo compound of each thermosensitive recording layer is encapsulated in thermoresponsive microcapsules, and is in a non-contact state with the coupler at room temperature.

When heat is applied to the magenta layer 24 by a thermal head or the like, similar to a single-layered thermosensitive recording material,
The reaction between the coupler M and the diazo compound M proceeds to form an image. Then, the decomposition wavelength λ1 (3
(90 nm to 440 nm), and the image is fixed. Next, when heat of a higher energy amount than that described above is provided by the thermal head, the diazo compound C in the cyan layer 23 reacts with the coupler C, and the printed portion develops cyan. As described above, the decomposition wavelength λ of the diazo compound C
2 (330 nm to 380 nm) is irradiated to fix the image. Next, similarly, when a higher energy amount of heat is supplied to the yellow layer 22, a yellow image is formed in the heat supplying portion, and a full-color image is obtained as a whole. Thereafter, the image may be fixed with light having a decomposition wavelength λ3 of the diazo compound Y. However, since the decomposition wavelength λ3 of the diazo compound Y is a very short wavelength and does not affect the image without decomposition, Image fixation need not be performed.

In FIG. 2, the yellow layer 22 may be a heat-sensitive recording layer containing an electron-donating dye precursor that develops yellow and an electron-accepting compound. In this case, light fixing of the yellow layer becomes unnecessary. A multicolor heat-sensitive recording material having three heat-sensitive recording layers, in which the layer 22 is a cyan layer, the layer 23 is a magenta layer, and the layer 24 is a yellow layer, by changing the type of the coupler to be used and the type of the electron-donating dye precursor. It may be. Further, two or more diazo compounds may be used in each heat-sensitive recording layer.

[0141]

EXAMPLES 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.

[Synthesis Example 1] 6.3 parts of pyrogallol sufficiently dried is dissolved in 43.9 parts of dry ethyl acetate. 37.6 parts of xylylene diisocyanate are added here. To this solution, 0.02 parts of stannous octylate (Stannoct, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) is added. Thereafter, the mixture is heated and stirred at 50 ° C. for 3 hours under a nitrogen stream, and a 50% solution of an isocyanate compound (isocyanate compound solution (1))
I got

[Synthesis Examples 2 to 9] Each of the isocyanate compounds (2) to (9) was prepared in the same manner as in Synthesis Example 1 except that the compounds used in Synthesis Example 1 were changed to the compounds shown in Table 1. % Solution (isocyanate compound solution (2) to
(9)) was obtained.

[0144]

[Table 1]

(Example 1) (Preparation of microcapsule solution A containing diazo compound) A diazo compound (exemplified compound (4)-) was added to 17.5 parts of ethyl acetate.
2) 4.4 parts and 7.5 parts of isopropyl biphenyl were added and mixed uniformly. Next, 5.6 parts of the isocyanate compound solution (1) obtained in Synthesis Example 1 as a capsule wall material and Takenate D110N (Takeda Pharmaceutical Co., Ltd. Trimethylolpropane and xylylene diisocyanate addition reaction product) 75% ethyl acetate solution)
7 parts, 4.2 parts of a 50% acetonitrile solution of a 50/50 weight ratio reaction product of Takenate D110N and polyethylene glycol monomethyl ether (Mw: about 4000) were added and mixed to obtain a homogeneous solution (I). Next, the homogeneous solution (I) was added to a mixture of 60 parts of an 8% aqueous solution of phthalated gelatin, 16.6 parts of water, and 2 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate.
Milk dispersion at 5000 rpm for 10 minutes. After adding 20 parts of water and 0.25 parts of diethylenetriamine to the obtained emulsion to homogenize, an encapsulation reaction was carried out at 40 ° C. for 1 hour with stirring, 30 parts of water was added, and 3 hours at 60 ° C.
Capsule liquid A was obtained by allowing the encapsulation reaction to proceed for an hour. The average particle size of the capsule was 0.58 micrometers.

(Preparation of Coupler Emulsion Dispersion B) In 3.2 parts of ethyl acetate, 2.2 parts of coupler (B-11), 2.3 parts of triphenylguanidine and 1.8 parts of tricresyl phosphate were dissolved. A liquid was obtained. Next, 31.4 parts of a 15% aqueous solution of lime-processed gelatin, 8.8 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, and 42.4 parts of water were added to 40 parts.
The solution II was added while uniformly mixed at a temperature of 0 ° C, and emulsified and dispersed at 10,000 rpm at 40 ° C using a homogenizer for 10 minutes. After stirring the obtained emulsion at 40 ° C. for 2 hours to remove ethyl acetate, the amount of evaporated ethyl acetate and water was not reduced by water to obtain a coupler emulsified dispersion B.

(Preparation of Coating Solution C for Thermosensitive Recording Layer) 1.4 parts of Capsule Liquid A, 0.7 parts of water, Emulsion Dispersion of Coupler B 6.2
And 1.7 parts of an 8% aqueous solution of phthalated gelatin,
A thermosensitive recording layer coating solution C was obtained.

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

(Coating) A thermosensitive recording layer coating solution C and a protective layer coating solution D were sequentially coated and dried at 50 ° C. in that order on a photographic paper support obtained by laminating polyethylene on high quality paper with a wire bar. A heat-sensitive recording material was obtained. The coating amounts as solids were 8.0 g / m ² and 1.2 g / m ^{2, respectively.}
Met.

[Examples 2 to 9] The isocyanate compound solution (1) obtained in Synthesis Example 1 was used in Synthesis Examples 2 to 8 respectively.
A diazo compound-containing microcapsule solution A was prepared in the same manner as in Example 1 except that the isocyanate compound solutions (2) to (9) obtained in the above were used, and a thermosensitive recording material was obtained in the same manner as in Example 1. Was.

[Comparative Example 1] 5.6 parts of the isocyanate compound solution (1) obtained in Synthesis Example 1 and Takenate D1
The portion corresponding to 2.7 parts of 10N was taken with Takenate D11
A diazo compound-containing microcapsule liquid A was prepared in the same manner as in Example 1, except that one type of 0N was changed to 6.4 parts (the solid content of the wall material was equivalent to that of Example 1).
A heat-sensitive recording material was obtained in the same manner as in Example 1.

[Comparative Example 2] 5.6 parts of the isocyanate compound solution (1) obtained in Synthetic Example 1 was mixed with millionate MR.
A diazo compound-containing microcapsule liquid A was prepared in the same manner as in Example 1 except that 2.8 parts (manufactured by Nippon Polyurethane Industry Co., Ltd.) were changed to 2.8 parts (the solid content of the wall material was equivalent to that of Example 1). Then, a heat-sensitive recording material was obtained in the same manner as in Example 1.

Using the heat-sensitive recording materials obtained in Examples 1 to 9 and Comparative Examples 1 and 2, the following color development test, light resistance test and thermo test were carried out. Table 2 shows the results.

(Coloring test) Using a thermal head (KST type) manufactured by Kyocera Corporation, the recording energy per unit area was 45 mj / mm ² , 60 mj / mm ² , 90 mj /
The power applied to the thermal head and the pulse width were determined so as to obtain mm ^2, and the image was obtained by thermal printing on the thermosensitive recording material. The coloring density and the background density were measured. Here, the color density refers to the density of the image portion, and the background density refers to the density of the non-image portion. (Light fastness test) Thermal head (KS
(T-type) was used to irradiate the color-developed portion with a fluorescent lamp tester at 30,000 lux for 72 hours, and then the optical reflection density of the background portion was measured. (Thermo Test) After leaving the obtained heat-sensitive recording material in a constant temperature and high humidity bath maintained at 40 ° C. and a relative humidity of 90% for 20 hours, it was fixed and the optical reflection density of the background was measured. (Density measurement) Color density and background density are measured using a densitometer "Macb
The optical reflection density at the Y position was measured using “eth RD918”.

[0155]

[Table 2]

According to Table 2, the heat-sensitive recording material using the microcapsules of the present invention did not develop color when low energy was applied, but developed color only when heat was applied at an energy of 60 mJ / mm ² , and further applied energy. Then, it can be seen that a sufficient color density can be obtained. Light resistance test,
It can be seen that the density of the background is kept low (that is, no fog or coloring occurs) even after the thermotest.

(Example 10) [Preparation of coating solution (1) for thermosensitive recording layer] <Preparation of capsule solution containing diazo compound> Diazo compound A
2.8 parts of a diazo compound represented by the following structural formula 1 having a maximum absorption wavelength of decomposition at 365 nm, and 0.2 parts of a diazo compound represented by the following formula 2 having a maximum absorption wavelength of decomposition at 420 nm as diazo compound B. 08 parts, dibutyl sulfate 2.8 parts, and ethyl acetate 19.0 parts.
To this solution, 5.9 parts of isopropyl biphenyl as a high boiling point solvent and 2.5 parts of tricresyl phosphate were further added, and the mixture was heated and uniformly mixed. To this solution, 7.6 parts of xylylene diisocyanate / trimethylolpropane adduct (75% ethyl acetate solution, Takeda Pharmaceutical Co., Ltd., Takenate D110N) was further added as a capsule wall material, and the mixture was stirred uniformly. . Separately, 64 parts of a 6% by weight aqueous solution of gelatin (manufactured by Nippi Gelatin Industries, Inc., MGP-9066) to which 2.0 parts of a 10% by weight aqueous solution of sodium dodecyl sulfonate were added, and the above solution of the diazo compound was added thereto. Then, the mixture was emulsified and dispersed by a homogenizer. After 20 parts of water was added to the obtained emulsified dispersion to homogenize, the temperature was raised to 40 ° C. while stirring, and an encapsulation reaction was performed for 3 hours.
Thereafter, the liquid temperature was lowered to 35 ° C., and 6.5 parts of an ion exchange resin (Amberlite IRC50 manufactured by Organo) and 6.5 parts of an ion exchange resin (Amberlite IRC50 manufactured by Organo).
13 parts were added and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was filtered to prepare a target capsule liquid. The average particle size of the microcapsules was 0.64 μm.

[0158]

Embedded image

<Preparation of Coupler Emulsion Dispersion> 3.0 parts of a compound represented by the following structural formula 3 as a coupler, 4.0 parts of triphenylguanidine as a base, and 1,1-
4.0 parts of (p-hydroxyphenyl) -2-ethylhexane, 8.0 parts of 4,4 ′-(p-phenylenediisopropylidene) diphenol, 2-ethylhexyl-4
8.0 parts of hydroxybenzoate, 2.0 parts of a compound represented by the following structural formula 4 as an antioxidant,
1,3, -tris (2-methyl-4-hydroxy-5-
2.0 parts of t-butylphenyl) butane and 1 part of ethyl acetate
The mixture was dissolved in 0.5 part, and 0.48 part of tricresyl phosphate, which is a high boiling point solvent, 0.24 part of diethyl maleate, and 1.27 part of pionin A41C (manufactured by Takemoto Yushi Co., Ltd.) were added, followed by heating. Mix evenly. This was separately added to 93 parts of an aqueous 8% by weight gelatin ("# 750 gelatin", manufactured by Nitta Gelatin Co., Ltd.) and emulsified and dispersed by a homogenizer. The remaining ethyl acetate was evaporated from this emulsified dispersion to prepare a desired coupler emulsified dispersion.

[0160]

Embedded image

<Preparation of Coating Solution for Thermosensitive Recording Layer> A diazo compound-containing capsule solution, a coupler emulsified dispersion, and a styrene-butadiene rubber ("SBR: SN307", manufactured by Sumitomo Nogatack Co., Ltd.) were each used as a diazo compound A / coupler. And the ratio of diazo compound A and diazo compound B / styrene-butadiene rubber is reduced to 1/2.
6.4, and further mixed such that the ratio of L-ascorbic acid ("Vitamin C", manufactured by Takeda Pharmaceutical Company Limited) / diazo compound A becomes 1/40, and A coating solution (1) was prepared.

[Preparation of Coating Solution for Protective Layer] 5.0% by weight of itaconic acid-modified polyvinyl alcohol (“KL-31
8 ", manufactured by Kuraray Co., Ltd.) in 61 parts of an aqueous solution, 20.5% by weight of zinc stearate dispersion (" Hydrin F115 ",
2.0 parts by weight of Chukyo Yushi Co., Ltd. were added, and C ₁₂ H ₂₅ O (C
8.4 parts of a 2% by weight aqueous solution of H ₂ CH ₂ O) H, 8.0 parts of a fluorine-based release agent (“ME-313”, manufactured by Daikin),
And flour starch ("KF-4", Kagoshima Starch Co., Ltd.) 0.5
Was added and stirred uniformly. This will be referred to as "mother liquor". Separately, 12.5 parts of a 20% by weight aqueous solution of ion-exchanged chao gloss (manufactured by Shiraishi Industry Co., Ltd.)
0.06 parts (manufactured by Kao Corporation), 1.87 parts of Hydrin Z-7 (manufactured by Chukyo Yushi Co., Ltd.), 1.25 parts of 10% by weight polyvinyl alcohol ("PVA105", manufactured by Kuraray Co., Ltd.), and
2% by weight aqueous solution of sodium dodecyl sulfonate 0.39
Parts were mixed and finely dispersed with a Dynomill. This liquid is referred to as “pigment liquid”. 4.4 parts of the pigment liquid was added to 80 parts of the mother liquor and stirred for 30 minutes or more. After that, Wet
2.8 parts of master500 (manufactured by Toho Chemical Co., Ltd.) was added, and the mixture was further stirred for 30 minutes or more to prepare a target coating liquid for a protective layer.

[Preparation of Coating Solution (2) for Thermosensitive Recording Layer] <Preparation of Capsule Solution for Electron Donating Dye Precursor> 3- (o-methyl-p-diethylaminophenyl) -3 was used as the electron donating dye precursor. 0.39 parts of-(1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 2
-Hydroxy-4-methoxybenzophenone 0.19
Was dissolved in 0.93 part of ethyl acetate, and 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, xylylene diisocyanate / trimethylolpropane adduct (75% by weight ethyl acetate solution: “Takenate D110”)
N ", manufactured by Takeda Pharmaceutical Co., Ltd.) was further added to this solution, and the mixture was stirred uniformly.

Separately, 6% by weight gelatin (“M”) to which 0.07 part of a 10% aqueous solution of sodium dodecyl sulfonate was added.
GP-9066 ", manufactured by Nippi Gelatin Industries) Aqueous solution 3
6.4 parts were prepared, and the above-mentioned electron donor dye precursor solution was added thereto, and the mixture was emulsified and dispersed with a homogenizer to obtain an emulsified dispersion (hereinafter, referred to as "primary emulsified dispersion"). Separately, 3-
(O-methyl-p-diethylaminophenyl) -3-
(1-ethyl-2-methylindol-3-yl) -4
-6.0 parts of azaphthalide, 3.0 parts of 2-hydroxy-4-methoxybenzophenone and 4.4 parts of 2,5-tert-octylhydroquinone are dissolved in 14.4 parts of ethyl acetate, and the solvent is a high boiling point solvent. To a solution obtained by adding 8.4 parts of phenethyl cumene and uniformly stirring, 7.8 parts of “Takenate D110N” used earlier and 11.8 parts of the isocyanate compound solution (1) obtained in Synthesis Example 1 were added. And stirred uniformly. This solution and 1.2 parts of a 10% aqueous sodium dodecyl sulfonate solution were added to the primary emulsified dispersion described above, and emulsified and dispersed with a homogenizer to obtain an emulsified dispersion (hereinafter, referred to as “second emulsified dispersion”). Liquid ").
To this secondary emulsified dispersion, 60.0 parts of water and 0.4 part of diethylenetriamine were added, and the mixture was homogenized.
The temperature was raised to 5 ° C., and the encapsulation reaction was carried out for 3.5 hours to obtain the desired electron-donating dye precursor capsule liquid. The average particle size of the capsule was 1.7 μm.

<Preparation of Electron-Accepting Compound Dispersion> Bisphenol P (30 parts) was used as an electron-accepting compound in gelatin ("MGP-9066", manufactured by Nippi Gelatin Industries Co., Ltd.).
22.5% by weight of a 2.0% by weight aqueous solution
Aqueous solution of sodium ethylhexylsulfosuccinate7.
5 parts were added, and the mixture was dispersed in a ball mill for 24 hours to prepare a dispersion. To this dispersion, 15% by weight aqueous solution of gelatin (“# 750 gelatin”, manufactured by Nitta Gelatin Co., Ltd.) was added.
6.0 parts were added, and the mixture was stirred uniformly to obtain a target dispersion of the electron-accepting compound. The average particle size of the electron accepting compound in the dispersion was 0.5 μm.

<Preparation of Coating Solution for Thermosensitive Recording Layer> An electron-donating dye precursor capsule solution, an electron-accepting compound dispersion,
15% by weight gelatin ("# 750 gelatin", Nitta Gelatin Co., Ltd.) aqueous solution, stilbene-based optical brightener ("Whi
tex-BB "(manufactured by Sumitomo Chemical Co., Ltd.) at a content weight ratio of electron-donating dye / electron-accepting compound of 1/14 and a weight ratio of electron-donating dye precursor /"# 750 gelatin "of 1.14. 1/1 and the content ratio by weight of the electron-donating dye precursor / fluorescent whitening agent was 5.3 / 1 to obtain the intended coating solution (2) for the heat-sensitive recording layer.

[Preparation of Coating Solution (1) for Intermediate Layer] 14 wt.
% Gelatin (“# 750 gelatin”, Nitta Gelatin Co., Ltd.)
8.2 parts of a 4% by weight aqueous solution of boric acid
Nylphenoxytrioxyethylene) butylsulfonic acid
1.2 parts of a 2% by weight aqueous solution of sodium, (CH_Two= CH
SO_TwoCH _TwoCONHCH_Two)-(CH_TwoNHCOCH_TwoS
O_TwoCH = CH_Two) And CH_Two− (CH _TwoNHCOCH_TwoSO
_TwoCH = CH_Two)_Two2% by weight of a 3: 1 mixture (weight ratio) of
Add 7.5 parts of an aqueous solution, stir evenly, and mix
An application liquid (1) was obtained.

[Preparation of Coating Solution for Light Transmittance Adjusting Layer] A compound represented by the following structural formula 6 (5.3 parts) was prepared by adding ethyl acetate 6.3.
6 parts and 2.9 parts of a phthalate ester solvent represented by the following structural formula 5 were mixed. Xylylene diisocyanate / trimethylolpropane adduct (75% ethyl acetate solution: “Takenate D110N”) as a capsule wall material,
2.0 parts (manufactured by Takeda Pharmaceutical Co., Ltd.) was added to this solution, and the mixture was stirred to be uniform. Separately, 60 parts of a 10% by weight aqueous solution of polyvinyl alcohol ("PVA217E", manufactured by Kuraray Co., Ltd.) to which 3.2 parts of a 10% by weight aqueous solution of sodium dodecylsulfonate were added was prepared, added to the above solution, and homogenized. Emulsified and dispersed. The obtained emulsified dispersion was heated to 50 ° C. while stirring, and an encapsulation reaction was performed for 3 hours to obtain a capsule liquid. The average particle size of the capsule in the capsule liquid was 0.2 μm. 50 parts of ion-exchanged water was added to 13 parts of the capsule liquid, and the mixture was stirred uniformly to prepare a target coating liquid for a light transmittance adjusting layer.

[0169]

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[Preparation of Coating Solution (3) for Thermosensitive Recording Layer] <Preparation of Microcapsule Solution Containing Diazo Compound> A diazo compound represented by the following structural formula 7 (decomposition absorption wavelength 420
3.5), 0.9 parts of a diazo compound represented by the following structural formula 8 (decomposition absorption wavelength: 420 nm) and 16.4 parts of ethyl acetate, and isopropyl biphenyl which is a high boiling point solvent. 8 parts were added and mixed by heating. As a capsule wall material, 4.5 parts of xylylene diisocyanate / trimethylolpropane adduct (75% ethyl acetate solution: "Takenate D110N", manufactured by Takeda Pharmaceutical Co., Ltd.), 30% by weight of xylylene diisocyanate / bisphenol A adduct A further 4.2 parts of ethyl acetate solution were added to this solution and stirred uniformly.

Separately, ScrapAG is used as a surfactant.
77 parts of a 6% by weight gelatin aqueous solution to which 0.36 parts of -8 (manufactured by Nippon Seika Co., Ltd.) was added was prepared, and the above diazo compound solution was added, followed by emulsification and dispersion with a homogenizer. After adding 20 parts of water to the obtained emulsified dispersion and homogenizing the mixture, the mixture was heated to 40 ° C. with stirring and subjected to a capsule reaction for 3 hours. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of an ion exchange resin “Amberlite IRA68” (manufactured by Organo) and 13 parts of “Amberlite IRC50” (manufactured by Organo) were added, and 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 and stirred. Thus, the desired capsule liquid was obtained. The average particle size of the capsule was 0.91 μm.

[0172]

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<Preparation of Coupler Emulsion Dispersion> As a coupler, 2.4 parts of a compound represented by the following structural formula 9, 2.5 parts of triphenylguanidine, 1,1- (p-hydroxyphenyl) -2-ethylhexane 2.5 parts, 4,4 '
3.6 parts of-(p-phenylenediisopropylidene) diphenol, 3.2 parts of 2-ethylhexyl-4-hydroxybenzoate, 0.8 part of the compound represented by the following structural formula 10, and 8.8 parts of ethyl acetate. After dissolving in 0 parts, 1.0 part of "Bionin A41C" (manufactured by Takemoto Yushi Co., Ltd.) was added, and the mixture was heated and uniformly mixed. Separately, it was added to 75.0 parts of a 10% by weight aqueous gelatin solution ("# 750 gelatin", manufactured by Nitta Gelatin Co., Ltd.), and then emulsified and dispersed with a homogenizer. The remaining ethyl acetate was evaporated to obtain the desired coupler emulsified dispersion.

[0174]

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<Preparation of Coating Solution for Thermosensitive Recording Layer> A diazo compound-containing microcapsule solution, a coupler emulsified dispersion,
Further, styrene-butadiene rubber (“SBR: SN30
7 ", manufactured by Sumitomo Nogatack Co., Ltd.) such that the weight ratio of the diazo compound to the coupler is 1 / 3.2,
Further, the styrene-butadiene rubber was mixed so that the weight of the styrene-butadiene rubber was equal to the weight of the gelatin of the coating solution to obtain a coating solution (3) for a heat-sensitive recording layer.

[Preparation of Coating Solution (2) for Intermediate Layer] 2 parts by weight of sodium (4-nonylphenoxytrioxyethylene) butylsulfonate was added to 57 parts of a 13% aqueous gelatin solution.
Aqueous solution 0.4 part, (CH ₂ 2CHSO ₂ CH ₂ CONHC
_{H 2) - (CH 2 NHCOCH} 2 SO 2 CH = CH 2) and C
_{H 2 - (CH 2 NHCOCH 2} SO 2 CH = CH 2) 2 of 3:
8.3 parts of a 2% by weight aqueous solution of 1 mixture (weight ratio), "PV
P-k15 "(manufactured by GAF Gokyo Sangyo Co., Ltd.) (2.4 parts) was added thereto, and the mixture was stirred uniformly to prepare a target coating solution (2) for an intermediate layer.

[Manufacture of thermosensitive recording material]
Place the Meyer Bar on the photographic paper support
And the coating solution for the heat-sensitive recording layer (2) and the coating solution for the intermediate layer
(1), coating solution for heat-sensitive recording layer (1), coating solution for intermediate layer
(2), coating solution for heat-sensitive recording layer (3), for light transmittance adjusting layer
The coating solution and the coating solution for the protective layer are sequentially applied from the support side
And dried to form a thermosensitive recording material having three thermosensitive recording layers.
Produced. Each coating amount was 7.12 g / dry weight.
m ^Two3.28 g / m^Two, 8.33 g / m^Two3.13 g
/ M^Two, 8.06 g / m^Two, 2.50 g / m^TwoAnd 1.2
3g / m^TwoMet.

The obtained heat-sensitive recording material was printed using the above-mentioned thermal head by (1) deciding the applied power and pulse width to the thermal head so that the recording energy per unit area was 35 mJ / mm ^2, and printed. Images were recorded. After that, the emission center wavelength was 420 nm and the output was 4
Exposed for 10 seconds under 0W ultraviolet lamp, (2) Again,
Printing was performed with the applied power and pulse width determined so that the recording energy per unit area was 66 mJ / mm ^2, and a magenta image was recorded. After that, the luminescence center 365n
m, irradiate an ultraviolet lamp of 40 W output for 15 seconds, (3)
Again the recording energy per unit area is 90 mJ / mm
Printing was performed with the power applied to the thermal head and the pulse width determined so as to be ^2, 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 records overlap is red, the portion where magenta and cyan overlap is blue, the portion where yellow and cyan overlap is green, and the image portion where the yellow, magenta and cyan records overlap is It developed a black color. When the obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1, the background density was 0.14, which was very good.

(Comparative Example 3) 7.8 parts of Takenate "D110N" used as an isocyanate compound and Synthesis Example 1
11.8 parts of the isocyanate compound (1) obtained in
15.7 parts of Takenate "D110N" (the solid content of the wall material is equivalent to the coating solution for the heat-sensitive recording layer (2)) (the average particle size of the capsule is 2). A heat-sensitive recording material was obtained in the same manner as in Example 10, except for using 1.3 μm). When printing was performed on the obtained heat-sensitive recording material in the same manner as in Example 10, a part of the cyan layer was also colored when the magenta layer was colored, a pure magenta-colored image was not obtained, and the image quality was very low. Was something. When the obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1, the background density was 0.13, which was very good.

(Comparative Example 4) The isocyanate compound (1) obtained in Synthesis Example 1 used as an isocyanate compound
The heat-sensitive recording layer coating solution (2) (11.8 parts) was changed to 5.9 parts of the millionate “MR200” (the solid content of the wall material is equivalent to the heat-sensitive recording layer coating solution (2)). A thermosensitive recording material was obtained in the same manner as in Example 10, except that the average particle size of the capsule was 1.4 μm. When printing was performed on the obtained heat-sensitive recording material in the same manner as in Example 10, good images were obtained as in Example 10 for each color-developed image. However, when the obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1, the background density was 0.28, which was a very large discoloration.

(Example 11) [Preparation of coating solution (4) for thermosensitive recording layer] Instead of the coupler emulsifying dispersion in coating solution (1) for thermosensitive recording layer, a coupler emulsifying dispersion prepared as follows was used. Except for using, a coating solution (4) for a thermosensitive recording layer was obtained in the same manner as the coating solution (1) for a thermosensitive recording layer.

<Preparation of Coupler Emulsion Dispersion> 3.0 parts of a coupler (pyrrolopyrimidione coupler) represented by the following structural formula 11, 3.6 parts of triphenylguanidine as a base, and 4,4′- 6.6 parts of (p-phenylenediisopropylidene) diphenol were added to ethyl acetate 1
The mixture was dissolved in 0.5 part, and 0.48 part of tricresyl phosphate, a high boiling point solvent, 0.24 part of diethyl maleate, and 1.27 part of Bionin A41C (manufactured by Takemoto Yushi Co., Ltd.) were added, followed by heating. Mix evenly. This was separately added to 93 parts of an aqueous solution of 8% by weight of gelatin (manufactured by Nitta Gelatin Co., Ltd., # 750 gelatin), and emulsified and dispersed by a homogenizer. The remaining ethyl acetate was evaporated from this emulsified dispersion to prepare a desired coupler emulsified dispersion.

[0183]

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[Preparation of Coating Solution (5) for Thermosensitive Recording Layer] <Preparation of Microcapsule Solution Containing Diazo Compound> In 13.7 parts of ethyl acetate, 4.6 parts of a diazo compound represented by the following structural formula 12 and phthalic acid were added. Diphenyl ester 10.4
Parts were added and mixed uniformly. Next, 5.5 parts of “Takenate D110N” (manufactured by Takeda Pharmaceutical Co., Ltd.) as a wall material and 5.6 parts of the aqueous isocyanate compound solution (8) obtained in Synthesis Example 8 were added to the mixture to obtain a liquid X. next,
67.4 parts of 8% aqueous solution of phthalated gelatin and 17.4 parts of water
Part, sucrapAG-8 (manufactured by Nippon Seika Co., Ltd.)
The above-mentioned liquid X was added to 0.4 parts of the mixed liquid, and emulsified and dispersed at 40 ° C. and a rotation number of 8000 rpm for 10 minutes using a homogenizer. After 50 parts of water and 0.26 parts of diethylenetriamine were added to the obtained emulsion to homogenize it, a microcapsulation reaction was carried out at 60 ° C. for 3 hours with stirring to obtain a desired capsule liquid. The average particle size of the microcapsules was 0.6 μm.

[0185]

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<Preparation of Coupler Emulsion Dispersion> 3.5 parts of the compound represented by the structural formula 3 as a coupler and 1.9 parts of triphenylguanidine were used as couplers in 12.5 parts of ethyl acetate.
And tricresyl phosphate (3.3 parts) were dissolved to obtain a liquid Y. Next, a 15% aqueous solution of lime-processed gelatin 50
Part, an aqueous solution obtained by uniformly mixing 0.5 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate and 50 parts of water at 40 ° C., and emulsifying at 40 ° C. and 10,000 rpm for 10 minutes using a homogenizer. Dispersed. The obtained emulsion was stirred at 40 ° C. for 2 minutes to remove ethyl acetate, and water was added to obtain a coupler emulsified dispersion.

<Preparation of Coating Solution for Thermosensitive Recording Layer> 10 parts of a diazo compound-containing microcapsule solution and 30 parts of a coupler emulsified dispersion were mixed to obtain a coating solution (5) for a thermosensitive recording layer.

[Preparation of Coating Solution (6) for Thermosensitive Recording Layer] <Preparation of Microcapsule Solution Containing Diazo Compound> In 19 parts of ethyl acetate, 2.8 parts of a diazo compound represented by the following structural formula 13 and tricresyl phosphate were added. 10 parts and mixed uniformly. Next, 7.6 parts of Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) was added as a wall material to the mixed solution, and mixed to obtain Liquid I. Next, the above-mentioned solution I was added to a mixture of 46 parts of an 8% aqueous solution of phthalated gelatin, 17.5 parts of water, and 2 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, and the mixture was added at 40 ° C and 10,000 rpm using a homogenizer.
Milk dispersed for 0 minutes. After adding 20 parts of water to the obtained emulsion to homogenize it, an encapsulation reaction was carried out at 40 ° C. for 3 hours with stirring to obtain a desired capsule liquid. The average particle size of the capsule was 0.7-0.8 micrometers.

[0189]

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<Preparation of Coupler Emulsion Dispersion> Coupler 3 represented by the following structural formula 14 was added to 10.5 parts of ethyl acetate.
, 3 parts of triphenylguanidine, 0.5 part of tricresyl phosphate and 0.24 part of diethyl maleate were dissolved to obtain a solution II. Next, 49 parts of a 15% aqueous solution of lime-processed gelatin, 9.5 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, and 35 parts of water were uniformly mixed at 40 ° C., and II solution was added. ° C, 10
The mixture was emulsified and dispersed at 000 rpm for 10 minutes. After stirring the obtained emulsion at 40 ° C. for 2 hours to remove ethyl acetate, the amounts of evaporated ethyl acetate and water were supplemented with water to obtain a coupler emulsified dispersion.

[0191]

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<Preparation of Coating Solution for Thermosensitive Recording Layer> 3.6 parts of a diazo compound capsule solution, 3.3 parts of water and 9.5 parts of a coupler emulsified dispersion were mixed to prepare a coating solution (6) for a thermosensitive recording layer. Obtained.

[Production of thermosensitive recording material] A coating solution for thermosensitive recording layer (5) was coated on a photographic paper support obtained by laminating polyethylene on wood free paper, using a Meyer bar in the same manner as in Example 9.
Coating solution for intermediate layer (1), coating solution for heat-sensitive recording layer (4), coating solution for intermediate layer (2), coating solution for heat-sensitive recording layer (6), coating solution for light transmittance adjusting layer, and Examples The coating solution for protective layer prepared in 1 was applied sequentially from the support side and dried to prepare a thermosensitive recording material having three thermosensitive recording layers. Each coating amount by dry weight ^{7.12g / m 2, 3.28g / m} 2,
^{8.33g / m 2, 3.13g / m} 2, 8.06g /
m ^2, and was 2.50 g / m ² and 1.23 g / m ^2.

The obtained heat-sensitive recording material was printed using the above-described thermal head by (1) determining the applied power and pulse width to the thermal head so that the recording energy per unit area was 35 mJ / mm ² , Images were recorded. After that, the emission center wavelength was 420 nm and the output was 4
The sheet was exposed to a 0 W ultraviolet lamp for 10 seconds, and (2) printing was performed again with the applied power and pulse width determined so that the recording energy per unit area was 66 mJ / mm ^2, and a cyan image was recorded. After that, an ultraviolet lamp having an emission center of 365 nm and an output of 40 W is irradiated for 15 seconds, and (3) printing is performed by again determining the applied power and pulse width to the thermal head so that the recording energy per unit area becomes 90 mJ / mm ² . A yellow image was recorded. As a result,
In addition to the yellow, magenta, and cyan color images, the recording portion where the yellow and magenta records overlap is red, the portion where magenta and cyan overlap is blue, the portion where yellow and cyan overlap is green, and the like. The image portion where the recordings of yellow, magenta, and cyan overlapped was colored black. The obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1. As a result, the background density was 0.15, which was very good.

(Comparative Example 5) 5.5 parts of Takenate "D110N" used as an isocyanate compound and Synthesis Example 8
In which 5.6 parts of the isocyanate compound (8) obtained in (1) above was changed to 9.2 parts of Takenate “D110N” (the solid content of the wall material is equivalent to the coating solution (5) for the heat-sensitive recording layer). A heat-sensitive recording material was obtained in the same manner as in Example 11 except that the recording layer coating solution (5) (the average particle size of the capsule was 1.3 μm) was used. When printing was performed on the obtained heat-sensitive recording material in the same manner as in Example 11, a part of the yellow layer was also colored when the cyan layer was colored, a pure cyan-colored image was not obtained, and the image quality was very low. Was something. When the obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1, the background density was 0.13, which was very good.

(Comparative Example 6) The isocyanate compound (8) obtained in Synthesis Example 8 used as an isocyanate compound
5.6 parts of the coating solution for the heat-sensitive recording layer (5) was changed to 2.8 parts of millionate “MR200” (the solid content of the wall material is equivalent to the coating solution for the heat-sensitive recording layer (5)). Example 1 except that the average particle size of the capsule was 1.3 μm).
In the same manner as in Example 1, a heat-sensitive recording material was obtained. When printing was performed on the obtained heat-sensitive recording material in the same manner as in Example 11, good images were obtained as in Example 11 for each color-developed image.
However, when the obtained heat-sensitive recording material was subjected to a light resistance test in the same manner as in Example 1, the background density was 0.30, which was a very large discoloration.

[0197]

As described above, according to the present invention, a color can not be formed at a low energy application, which is suitable for a heat-sensitive recording material and a multicolor heat-sensitive recording material, and a sufficiently high color density can be realized at a high energy application. Provided are microcapsules that are possible, have little fog during storage and yellow coloring over time due to light irradiation, and can be supplied at low cost, and a thermosensitive recording material and a multicolor thermosensitive recording material using the same. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a heat-sensitive recording material of the present invention.

FIG. 2 is a schematic sectional view showing an example of the multicolor heat-sensitive recording material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Support 12 Thermal recording layer 13 Protective layer 21 Support 22 Yellow layer (thermal recording layer) 13 Cyan layer (thermal recording layer) 24 Magenta layer (thermal recording layer) 25, 26 Intermediate layer 27 Ultraviolet transmittance adjusting layer (light) (Transmittance adjusting layer) 28 Protective layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H026 AA07 AA14 AA28 AA32 BB01 BB41 DD01 DD45 DD48 DD53 FF05 FF07 HH03 4G005 AA01 AB14 AB27 BA02 BB06 DB27X DC09X DC18Y DC41W DC41X DC42Y DC46Y DD02Z DD04Z DD08 DD08 DD08

Claims (3)

[Claims] 1. A microcapsule containing a diazo compound or an electron-donating dye precursor, wherein the capsule wall of the microcapsule is represented by at least (A) the following general formula (1) and / or (2): A microcapsule comprising a polymer obtained by polymerization of an isocyanate compound containing an adduct of a compound and (B) a polyfunctional isocyanate having at least two isocyanate groups in a molecule. Embedded image (In the general formulas (1) and (2), R ¹ , R ² , R ³ , and R ⁴ are
Each independently represents hydrogen, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, an aralkyl group, an aryl group, —COOR ⁵ ,
—CONR ⁶ R ⁷ represents a halogen, a cyano group, or a nitro group. R ⁵ , R ⁶ , and R ⁷ each independently represent hydrogen, carbon atom 1
Represents an alkyl group, an aralkyl group, and an aryl group.
l and m each independently represent an integer of 0 to 3. However,
l + m is an integer of 3 or less. ) 2. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a microcapsule containing a diazo compound and a coupler, or a microcapsule containing an electron-donating dye precursor and a color developer. A heat-sensitive recording material, wherein the microcapsules are the microcapsules according to claim 1. 3. A microcapsule and a coupler each having a support and two or more heat-sensitive recording layers capable of coloring in any of cyan, magenta, and yellow, wherein each heat-sensitive recording layer contains a diazo compound, or A multicolor heat-sensitive recording material comprising a microcapsule containing an electron-donating dye precursor and a developer, wherein the microcapsules in at least one of the heat-sensitive recording layers are the microcapsules according to claim 1. A multicolor heat-sensitive recording material characterized by the following: