JP2003127548A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material markedly excellent in light fastness and capable of effectively suppressing texture exposed coloration. SOLUTION: In the thermal recording material wherein at least one thermal recording layer is provided on a support, at least one layer of which the oxygen permeability is not more than 0.7 is provided on each of the upper and rear surfaces of the thermal recording layer. Preferably, the oxygen permeability of the thermal recording layer is not more than 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-sensitive recording material having light resistance.

[0002]

2. Description of the Related Art Thermal recording has been developed in recent years due to its simple recording device, high reliability and maintenance-free. Conventionally, the reaction between a diazonium salt compound and a coupler has been used as the thermal recording material. And those utilizing the reaction between an electron-donating colorless dye and an electron-accepting compound are widely known.

However, in a heat-sensitive recording material using a diazonium salt compound or an electron-donating colorless dye, the background is colored by the photooxide generated by the coexistence of oxygen during light irradiation, which is one of the causes of the quality deterioration. . Therefore, it has been studied to reduce the coloring by adding an undercoat layer for the purpose of blocking oxygen, or by introducing an ultraviolet absorber precursor layer, but its effect was not sufficient.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above-mentioned problems, and is a heat-sensitive material which is excellent in light resistance while maintaining glossiness and which can effectively suppress background exposure coloration. An object is to provide a recording material.

[0005]

The above-mentioned problems can be solved by providing the following heat-sensitive recording material. <1> A heat-sensitive recording material having at least one heat-sensitive recording layer on a support, and at least one layer having oxygen permeability of 0.7 or less on each of the upper and lower sides of the heat-sensitive recording layer. It is a characteristic heat-sensitive recording material. <2> The thermosensitive recording material according to <1>, wherein the thermosensitive recording layer has an oxygen permeability of 10 or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording material of the present invention is a heat-sensitive recording material having at least one heat-sensitive recording layer on a support, and at least one layer is provided above and below the heat-sensitive recording layer.
A heat-sensitive recording material having a layer having an oxygen transmission rate of 0.7 or less, preferably a heat-sensitive recording material having an oxygen transmission rate of 10 or less.

Generally, the heat-sensitive recording material is provided with a light transmittance adjusting layer and a heat-resistant protective layer in addition to the heat-sensitive recording layer, and other layers appropriately selected according to the purpose, for example, the support and the heat-sensitive recording layer. The heat-sensitive recording layer of the present invention includes the case of the whole multi-layer heat-sensitive recording layer and the case of individual heat-sensitive recording layers, although it has an undercoat layer provided between the heat-sensitive recording layers. As long as it is a layer formed above and below the heat-sensitive recording layer, the layer having an oxygen transmittance of 0.7 or less according to the present invention can be used as a light transmittance adjusting layer, an intermediate layer, an undercoat layer, or any other layer. The case where it is formed is also included. The thermal recording material of the present invention will be described in detail below.

(Oxygen permeability) The oxygen permeability is a value measured under the following conditions, and the oxygen permeability in this specification is measured by this measuring method. First, a coating solution used for a specific layer is applied on a substrate so as to have a layer thickness of 1.5 μm to prepare a measurement sample. next,
Oxygen electrode (manufactured by Iijima Electronics Co., Ltd.) on the prepared sample:
GU-B) attached, temperature 25 ℃, humidity 50% RH
Under, digital multimeter (Advantest Corporation)
Manufactured) and the oxygen permeability is measured by the following conversion formula.

[0009]

[Equation 1] [In the formula, F: Faraday constant, A: cathode area, R: internal resistance, Ps: oxygen partial pressure, respectively. ]

(Layer having oxygen permeability of 0.7 or less) The heat-sensitive recording material of the present invention has at least one layer having oxygen permeability of 0.7 or less on each of the upper and lower sides of the heat-sensitive recording layer. And more preferably a thermosensitive recording material having an oxygen transmission rate of 10 or less in the thermosensitive recording layer.

The layer having an oxygen permeability of 0.7 or less is
As described above, the light transmittance adjusting layer, the intermediate layer, the undercoat layer, and any other layer is included, but the light transmittance adjusting layer and the undercoat layer are layers having the oxygen transmittance of 0.7 or less. Most preferably.

As means for lowering the oxygen transmission rate of each layer, polyvinyl alcohol, modified polyvinyl alcohol, styrene-maleic anhydride copolymer, butadiene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer are used. , Isobutylene-maleic anhydride copolymer,
Water-soluble polymers such as polyacrylamide, polystyrene sulfonic acid, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, gelatin and carboxymethyl cellulose, styrene-butadiene copolymer, carboxy-modified styrene-butadiene copolymer, acrylonitrile-butadiene copolymer It is effective to add a latex emulsion of a hydrophobic polymer such as a polymer, a layered compound having a high aspect ratio such as mica, and various pigments to each of the above layers.

In the present invention, it is particularly preferable that each of the above layers contains polyvinyl alcohol having a saponification degree of 90 mol% or more, modified polyvinyl alcohol, or the like. Specific examples of polyvinyl alcohol having a saponification degree of 90 mol% or more include PVA105, PVA117, and PVA12.
4, PVA117C, PVA124C (all manufactured by Kuraray Co., Ltd.) and the like are specific examples of the modified polyvinyl alcohol having a saponification degree of 90 mol% or more, KL118, K.
Carboxylic acid-modified polyvinyl alcohol such as M118 and KM618 (both manufactured by Kuraray Co., Ltd.), MP103
(Kuraray Co., Ltd.) and other terminal alkyl-modified polyvinyl alcohols, M115 (Kuraray Co., Ltd.) and other terminal thiol-modified polyvinyl alcohols, and the like. Among these, it is particularly preferable to add silanol-modified polyvinyl alcohol such as R1130, R2105, and R2130 (all manufactured by Kuraray Co., Ltd.). When each layer contains polyvinyl alcohol having a saponification degree of 90 mol% or more, the oxygen transmission rate of each layer is significantly reduced.

Among them, it is particularly preferable to contain polyvinyl alcohol represented by the following general formula (1).

[0015]

[Chemical 1]

In the formula, l, m, and n represent polymerization molar ratios,
1 represents a real number of 90 to 99, m is 0 to 10, and n is a number of 0 to 10. Among them, l is 95 to 99, m is 0 to 5, n is 0 to 5
Are preferred, and particularly, l is 98 to 99, m is 0 to 1, and n is
Is most preferably 0 to 1.

A, A'and A "represent C1 to C8 alkyl groups. As the alkyl groups of A, A'and A",
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, n-pentyl group, i
-Pentyl group, n-hexyl group, i-hexyl group, n-
A heptyl group, an i-heptyl group, an n-octyl group, an i-octyl group and the like can be mentioned. A, A ′ and A ″ may be the same group or may have a substituent.

When the saponification degree of the polyvinyl alcohol represented by the general formula (1) is 90 mol% or more, the crystallization of the polyvinyl alcohol during film formation is promoted, and the oxygen permeability is significantly reduced.

(Light transmittance adjusting layer) In the present invention, a light transmittance adjusting layer formed between the heat-sensitive recording layer and the protective layer is used.
It is preferable that the layer has an oxygen permeability of 0.7 or less according to the present invention. In this case, the polyvinyl alcohol having a high degree of saponification can be used in combination with other known water-soluble polymers. Other known water-soluble polymers include polyvinyl alcohol, silanol modified polyvinyl alcohol, carboxy modified polyvinyl alcohol, amino modified polyvinyl alcohol, itaconic acid modified polyvinyl alcohol, styrene-maleic anhydride copolymer, butadiene maleic anhydride copolymer. , Ethylene maleic anhydride copolymer, isobutylene maleic anhydride copolymer, polyacrylamide, polystyrene sulfonic acid, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, gelatin and the like. In the present invention, a surfactant or the like may be added to the water-soluble polymer, if necessary, or an emulsion or latex of a hydrophobic polymer may be used in combination. In the present invention, the content of polyvinyl alcohol having a saponification degree of 90 mol% or more is preferably 10% by mass or more of the light transmittance adjusting layer.

It is preferable that the light transmittance adjusting layer contains a component that functions as a precursor of an ultraviolet absorber, in addition to the polyvinyl alcohol. The component functioning as a precursor of the ultraviolet absorber functions as an ultraviolet absorber by reacting with light or heat after the irradiation of light having a wavelength in a region necessary for fixing the thermosensitive recording layer by irradiation of light is completed. As a result, most of the light of the wavelength in the region necessary for fixing in the ultraviolet region is absorbed by the ultraviolet absorber,
Although the transmittance is low and the light resistance of the heat-sensitive recording material is improved, the visible light transmittance is substantially unchanged because there is no visible light absorption effect.

Suitable examples of the component functioning as a precursor of the ultraviolet absorber include compounds represented by any of the following general formulas (2) to (5).

[0022]

[Chemical 2]

In the general formulas (2) to (5), m is 1
Or represents 2. A is —SO ₂ —R, —C in the general formula (2) and the general formulas (3) to (5) when m = 1.
_{O-R, -CO 2 -R,} -CONH-R, -POR
¹ R ^2, represents a -CH ₂ R ³ or -SiR ⁴ R ⁵ R ^6. Also,
A is -SO ₂ in the general formula (2) when m = _{2.
^{R 7 SO 2 -, - CO}} -, - COCO -, - COR 7 CO
-, - it represents or -SO- - SO _2.

X represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group or a halogen atom in the general formulas (2), (4) and (5). Further, X is an alkylene group, —OR ⁷ O— or —O in the general formula (3).
Represents COR ⁷ CO ₂ −. W represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group or a halogen atom in the general formulas (2), (3) and (5). Also, W is
In the general formula (4), —OR ⁷ O— or —OCOR ⁷ C
Represents O ₂ −.

Y represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group or a halogen atom in the general formulas (2), (3) and (4). In addition, Y is the general formula (5)
^{In, -OR 7 O -, - OCOR} 7 CO 2 -, - CH 2
_{^{CH 2 CO 2 R 7 OCOCH 2}} CH 2 -, - CH 2 CH 2 OC
_{^{OR 7 CO 2 CH 2 CH 2}} -, or, -CH ₂ CH ₂ CON
^{(R 8) R 7 N (} R 8) COCH 2 CH 2 - represents a.

Z represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. Here, R represents an alkyl group or an aryl group. R ¹ and R ² are alkoxy groups,
It represents an aryloxy group, an alkyl group or an aryl group.
R ³ represents a phenyl group substituted with at least one nitro group or methoxy group. R ⁴ , R ⁵ and R ⁶ represent an alkyl group or an aryl group. R ⁷ represents an alkylene group or an arylene group. R ⁸ represents a hydrogen atom or an alkyl group.

The alkyl group may be linear or branched, may have an unsaturated bond, and may be an alkoxy group, an aryloxy group, an alkoxycarbonyl group, It may be substituted with an aryloxycarbonyl group, an aryl group, a hydroxy group or the like. The aryl group may be further substituted with an alkyl group, an alkoxy group, or a halogen atom.

The alkylene group may be linear or branched, and may have an unsaturated bond, an oxygen atom,
It may contain a sulfur atom or a nitrogen atom. Moreover, the alkylene group may be further substituted with an alkoxy group, a hydroxy group, an aryloxy group, or an aryl group.

The arylene group is further an alkyl group,
It may be substituted with an alkoxy group or a halogen atom.

The substituents represented by X, Y, and W include an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, a fluorine atom and a chlorine atom. , A bromine atom or a hydrogen atom is preferable, and among these, an alkyl group having 1 to 12 carbon atoms and 1 to 1 carbon atoms
Particularly preferred are the 12 alkoxy groups, phenyl group, or hydrogen atom or chlorine atom.

The substituent represented by Z is a hydrogen atom,
Chlorine atom, fluorine atom, alkyl group having 1 to 12 carbon atoms,
An alkoxy group having 1 to 12 carbon atoms is preferable, and among these, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydrogen atom or a chlorine atom is particularly preferable.

The substituent represented by R has 1 to 1 carbon atoms.
An alkyl group having 18 carbon atoms and an aryl group having 6 to 18 carbon atoms are preferable, and among these, an alkyl group having 1 to 12 carbon atoms,
An aryl group having 6 to 12 carbon atoms is particularly preferable.

The substituent represented by R ¹ and R ² includes an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, and 6 to 6 carbon atoms.
12 aryl groups are preferred.

The substituent represented by R ³ includes 2-nitrophenyl group, 3,5-dimethoxyphenyl group, 3,
The 4,5-trimethoxyphenyl group is preferred.

The substituent represented by R ⁴ , R ⁵ and R ⁶ is preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and an alkyl group having 1 to 8 carbon atoms or phenyl. Groups are particularly preferred.

In the so-called bis form having two benzotriazole rings in one molecule, the substituent represented by R7 is an alkylene group having 1 to 12 carbon atoms or 6 to 12 carbon atoms.
The arylene group of 12 is preferable, and the substituent represented by R ⁸ is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

As the substituent represented by A, --SO ₂ R
Is particularly preferable.

Specific examples of the above substituents will be given below, but the present invention is not limited thereto. X, Y, and W
Examples of the monovalent substituents represented by are hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, Pentyl group, hexyl group, octyl group, decyl group, dodecyl group, allyl group, 2-butenyl group, benzyl group, α-dimethylbenzyl group, methoxy group, ethoxy group, propyloxy group, butyloxy group,
Octyloxy group, dodecyloxy group, methoxyethoxy group, phenoxyethoxy group, methoxycarbonylethyl group, ethoxycarbonylethyl group, propyloxycarbonylethyl group, butyloxycarbonylethyl group,
Examples thereof include an octyloxycarbonylethyl group, a phenoxycarbonylethyl group, a phenyl group, a tolyl group, a chlorine atom, a fluorine atom and a bromine atom. Examples of the divalent group include the following.

[0039]

[Chemical 3]

The substituent represented by Z is a hydrogen atom,
Examples thereof include chlorine atom, methyl group, ethyl group, propyl group, hexyl group, methoxy group, ethoxy group, propyloxy group and octyloxy group.

The monovalent substituents represented by A include methanesulfonyl group, ethanesulfonyl group, butanesulfonyl group, benzenesulfonyl group, 4-methylbenzenesulfonyl group, 2-mesitylenesulfonyl group, and 4
-Methoxybenzenesulfonyl group, 4-octyloxybenzenesulfonyl group, 2,4,6-triisopropylbenzenesulfonyl group, β-styrenesulfonyl group, vinylbenzenesulfonyl group, 4-chlorobenzenesulfonyl group, 2,5-dichlorobenzenesulfonyl group Base 2,
4,5-trichlorobenzenesulfonyl group, 1-naphthalenesulfonyl group, 2-naphthalenesulfonyl group, quinolinesulfonyl group, thiophenesulfonyl group, acetyl group, propionyl group, butyryl group, pivaloyl group, lauroyl group, stearoyl group, benzoyl group, Cinnamoyl group, furoyl group, nicotinoyl group, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl group, hexylaminocarbonyl group, phenylaminocarbonyl group, diphenylphosphoryl group, diethylphosphoryl group, 2-nitrobenzyl group, 3,5-dimethoxy group Benzyl group, 3,4,5-trimethoxybenzyl group, trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group, diethylisopropylsilyl group, dimethylphenylsilyl group, Phenylmethyl silyl group, and the like triphenylsilyl group are given below in as divalent.

[0042]

[Chemical 4]

When A is —SiR ⁴ R ⁵ R ^6, a photoacid generator such as an ammonium salt, a diazonium salt, an iodonium salt, a sulfonium salt, a phosphonium salt or an onium salt is used in combination for the purpose of improving photoreactivity. You may. Specific examples of these photo-acid generators include "organic materials for imaging" (edited by Organic Electronics Materials Research Group, 199).
3 years).

The compounds represented by the general formulas (2) to (5) can be easily synthesized by a conventionally known method, and they may be used alone or in combination of two or more. You may use together.

The mode of containing the compounds represented by the general formulas (2) to (5) in the light transmittance adjusting layer is not particularly limited and can be appropriately selected according to the purpose. These include (1) a solid dispersion method, (2) an emulsification dispersion method,
(3) Polymer dispersion-containing method, (4) Latex dispersion-containing method, (5) Microcapsule-containing method, and the like. Among these, the method of incorporating by emulsifying and dispersing and the method of incorporating by microencapsulating are preferable.

As a method of emulsifying and dispersing, first, the compounds represented by the general formulas (2) to (5) are dissolved in oil. This oil may be a solid at room temperature, may be a liquid, may be a polymer, and has a low boiling auxiliary solvent such as acetic acid ester, methylene chloride, cyclohexanone and / or a phosphoric acid ester, a phthalic acid ester. ,
Acrylic ester, methacrylic acid ester, other carboxylic acid ethesul, fatty acid amide, alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, chlorinated paraffin, alcohol system, phenol system, ether system, monoolefin system, Epoxy, etc. are mentioned. Specific examples include tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilaurate phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol benzoate, dioctyl sebacate, dibutyl sebacate, Dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isoamyl biphenyl,
Chlorinated paraffin, diisopropyl naphthalene, 1,1
′ -Ditolylethane, 2,4-dita-shariamylphenol, N, N-dibutyl-2-butoxy-5-tert-aryoctylaniline, hydroxybenzoic acid 2-ethylhexyl ester, high-boiling oil such as polyethylene glycol, and the like. To be These may be used alone or in combination of two or more, and among these, alcohol-based, phosphoric acid ester-based, carboxylic acid ester-based, alkylated biphenyl, alkylated terphenyl, Alkylated naphthalene and diarylethane are preferred. In the present invention, a carbonization inhibitor such as hindered phenol or hindered amine may be added to the oil.

The oil containing the compounds represented by the general formulas (2) to (5) is added to the aqueous solution of the water-soluble polymer and emulsified and dispersed by a colloid mill, a homogenizer or ultrasonic waves.

(Undercoat Layer) In the present invention, the undercoat layer provided between the support and the thermosensitive recording layer is preferably a layer having an oxygen permeability of 0.7 or less according to the present invention. Among them, the viscosity of PAGI method is 10 to 30 mP, P
It is preferable to contain gelatin having a jelly strength of 15 to 70 g according to the AGI method (hereinafter simply referred to as "gelatin") and a layered inorganic compound. In the present invention, the oxygen permeability of the undercoat layer can be reduced by containing such gelatin and the layered inorganic compound.

The viscosity of the PAGI method and the jelly strength of the PAGI method are the same as those of the Paggi method published by the Joint Examination Committee for Photographic Gelatin Testing Method: Photographic Gelatin Testing Method, 7th Edition (199).
It was measured based on the test by the 2nd year edition). The gelatin can be obtained by lowering the molecular weight of known gelatin produced by an ordinary method (hereinafter referred to as "ordinary gelatin"). However, the term "normal gelatin" as used herein means, for example, "raw and gelatin (raw materials such as cow bone, cow hide, pig skin, as described in Yoshihiro Abiko, Nippon Niwa, published by Gelatin Industry Association (1987). Is produced by treating lime with an acid or the like, and has much higher viscosity and jelly strength than the above gelatin.

The usual gelatin is characterized by conditions such as raw material, treatment method (for example, lime treatment, acid treatment) and extraction conditions (temperature, number of extractions). The gelatin may be obtained by lowering the molecular weight based on any gelatin, but the number of extractions is small, and the one extracted at low temperature can achieve both low viscosity and jelly strength within the above numerical range. Is preferred. Examples of the method for lowering the molecular weight include a method using an enzyme and a method using heat, and among these, the method using an enzyme is preferable. In the case of the method using heat, the jelly strength may decrease when the viscosity is reduced to a preferable value. Preferable examples of the enzyme include papain.

In the gelatin, the PAGI method has a viscosity of 10 to 30 mP, and the PAGI method has a jelly strength of 15 to 70 g. However, when the PAGI method has a viscosity of less than 10 mP, the viscosity of the coating solution decreases. Becomes larger,
The dispersed state of the pigment (mica) in the coating liquid may be deteriorated, and if it exceeds 30 mP, the viscosity of the coating liquid may be increased and the coating failure may be easily caused. When the jelly strength of the PAGI method is less than 15 g, the coating strength may decrease and the adhesive strength with the support may decrease, and when the jelly strength of the PAGI method is more than 70 g, the coating strength may decrease. The curl of the film may increase due to environmental changes.

If desired, the gelatin may be crosslinked with a hardener, and in this case, the hardener may be a known one used as a hardener for gelatin. Examples thereof include vinyl sulfone compounds, active halogen compounds, isocyanate compounds, epoxy compounds, and the like. Among these, an epoxy compound is particularly preferable, and as the epoxy compound, for example, the following compounds are suitable.

[0053]

[Chemical 5]

The coating amount of the gelatin in the undercoat layer is preferably 0.5 g / m ² or more from the viewpoint of suppressing a prestar (fine swelling phenomenon due to heat of the printer thermal head during recording of an image).

Preferable examples of the layered inorganic compound include swellable inorganic layered compounds. Specific examples of the swellable inorganic layered compound include bentonite, hectorite, saponite, beidellite, nontronite, stevensite, beidellite, swelling viscosity minerals such as montmorillonite, swelling synthetic mica, swelling synthetic smectite, and the like. Can be mentioned.

These swellable inorganic layered compounds have a laminated structure consisting of unit crystal lattice layers having a thickness of about 10 to 15 angstroms, and the substitution of metal atoms in the lattice is significantly larger than that of other clay minerals. As a result, the lattice layer causes a shortage of positive charges, and Na ⁺ , C between the layers are provided to compensate for it.
^Adsorbs cations such as a ²⁺ and Mg ²⁺ . The cations existing between these layers are called “exchangeable cations” and exchange with various cations. In particular, when the cations between the layers are Li ⁺ , Na ^+, etc., the ionic radius is small, so that the bond between the layered crystal lattices is weak and the layer swells greatly with water. When shear is applied in that state, it is easily cleaved to form a stable sol in water. Among the specific examples of the swellable inorganic layered compound, bentonite and swellable synthetic mica are preferable because of their strong tendency, and swellable synthetic mica is particularly preferable.

Suitable examples of the swellable synthetic mica include the following compounds. Na tetrasic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (NaLi) Mg ₂ (Si ₄ O ₁₀ ) F ₂ , Na or Li hectorite (NaLi) _{/ 3} Mg _2/3 Li _{1 / 3} (Si
₄ O ₁₀ ) F ₂ and the like.

The swelling synthetic mica has a thickness of 1 to 50 nm and a plane size of 1 to 20 μm. From the viewpoint of diffusion control, the thickness is preferably as thin as possible, and the plane size is preferably as large as possible in the range not deteriorating the smoothness and transparency of the coated surface. The aspect ratio of the swellable synthetic mica is usually 100 or more, preferably 200 or more, more preferably 500 or more.

When the above-mentioned ordinary gelatin is used, if the ratio of mica (to gelatin of 1.5 to 10 or more) is increased, the viscosity and gelation proceed at a constant solid concentration (for example, 5 to 10%). , It is necessary to lower the viscosity. To reduce the viscosity, there is a method of lowering the concentration, but lowering the concentration increases the drying load of the coating film, resulting in deterioration of the coated surface state due to thick coating. There is also a method of adding urea, salt or the like to the coating liquid, but the viscosity cannot be sufficiently reduced and the surface condition after coating is poor. On the other hand, the gelatin can remarkably reduce the thickening and gelation without causing such an adverse effect, and can remarkably reduce the thickening and gelation even when it is mixed with mica. , Is advantageous.

The content of the water-swellable synthetic mica in the undercoat layer is 1 / mass ratio of mica / gelatin.
20 to 1/2 are preferable. If the content of the water-swellable synthetic mica is less than 1/20, the undercoat layer may not function sufficiently as an oxygen barrier layer, and if it exceeds 1/2, the production suitability such as coating property may be poor. It may get worse.

The coating amount of mica in the undercoat layer is usually 0.01 g / m ² or more and 0.02 g.
/ M ² or more is preferable. The coating amount of the mica is 0.01
If it is less than g / m ² , the oxygen blocking ability of the undercoat layer may be deteriorated, and it may not be possible to exhibit the property of preventing coloring of the background portion.

(Intermediate Layer) In the present invention, when the thermosensitive recording layer has a laminated structure of thermosensitive coloring layers having different hues, an intermediate layer for preventing color mixture or the like is provided between the thermosensitive recording layers. It is preferable that the intermediate layer is a layer having an oxygen permeability of 0.7 or less according to the present invention. Also in this case, the oxygen permeability of the intermediate layer is reduced by using the polyvinyl alcohol having a saponification degree of 90% or more or the swelling inorganic layered compound. The known material is not particularly limited and can be formed using a water-soluble polymer compound or the like. Examples of the water-soluble polymer compound include polyvinyl alcohol, modified polyvinyl alcohol, methyl cellulose, sodium polystyrene sulfonate, styrene-maleic acid copolymer, gelatin and /
Alternatively, those comprising a zetillane derivative, polyethylene glycol and / or a polyethylene glycol derivative are preferred.

The inorganic layered compound can be preferably added to the intermediate layer. When the intermediate layer contains the inorganic layered compound, color transfer can be prevented by suppressing / preventing mass transfer between layers, and raw storage property and color image storage property are improved by suppressing supply of oxygen. Can be made.

(Protective Layer) The protective layer is a layer provided for sticking the heat-sensitive recording layer and protecting the heat-sensitive recording layer from a solvent and the like, and the oxygen permeability of the present invention is 0.7 or less. Can be a layer. in this case,
By using the polyvinyl alcohol having a high degree of saponification in combination with a known material appropriately selected according to the purpose of the protective layer, the oxygen permeability of the protective layer is reduced. As the binder preferably used in the protective layer, modified polyvinyl alcohol (silanol modified polyvinyl alcohol, long chain alkyl ether modified polyvinyl alcohol,
Acetoacetyl-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, etc.), polyvinyl alcohol silicone-modified polymer, carboxymethyl cellulose, hydroxyethyl cellulose, etc. may be used alone or in combination of two or more. In the present invention, the content of polyvinyl alcohol having a saponification degree of 90 mol% or more is preferably 10% by mass or more of the intermediate layer.

The protective layer preferably contains a pigment. As the pigment, inorganic ultrafine particles are preferable, and examples of the inorganic ultrafine particles include colloidal silica, zirconia oxide, barium sulfate, aluminum oxide (alumina), zinc oxide, magnesium oxide, calcium oxide, cerium oxide, titanium oxide and the like. These may be used alone or in combination of two or more.

The protective layer is preferably prepared by applying a protective layer coating solution containing silanol-modified polyvinyl alcohol and colloidal silica onto a heat-sensitive recording layer using a bar coater, air knife coater, blade coater, curtain coater or the like. Apply and dry. However, the protective layer may be applied at the same time as the heat-sensitive recording layer by a superposition method, or after the heat-sensitive recording layer or the like is applied, the heat-sensitive recording layer or the like may be dried and then applied. The dry coating amount of the protective layer is preferably 0.1 to 3 g / m ^{2, and} is 0.3 to 2.0.
g / m ² is more preferable. If the coating amount is large, the thermal sensitivity is remarkably lowered, and if the coating amount is too low, the function as a protective layer (friction resistance, lubricity, scratch resistance, etc.) cannot be exhibited. Further, after coating the protective layer, a calendering treatment may be carried out if necessary.

(Thermal Recording Layer) The thermal recording layer of the present invention preferably has an oxygen permeability of 10 or less. The heat-sensitive recording layer of the present invention is filled with minute voids present in the layer,
The oxygen permeability of the heat-sensitive recording layer can be 10 or less.

The heat-sensitive recording material of the present invention may have one heat-sensitive recording layer or a plurality of heat-sensitive recording layers. When providing multiple,
It is necessary to use color formers having different energies required for color development. The heat-sensitive recording material of the present invention may be full-color or mono-color, but it contains a diazonium salt compound on the support, a diazo color-forming agent containing a coupler that undergoes a coupling reaction with the diazonium salt compound, and a binder as main components. It is desirable to have at least one heat-sensitive recording layer (light fixing type heat-sensitive recording layer). Further, as the color former of the heat-sensitive recording layer, in addition to the above-mentioned diazo color former, a leuco color former containing an electron-donating dye and an electron-accepting compound, a base color-forming system that develops a color by contact with a basic compound, Any of a chelate coloring system, a coloring system that reacts with a nucleophile to cause an elimination reaction to develop a color, and the like may be used.

When the heat-sensitive recording layer contains the diazonium salt compound and a coupler which reacts with the diazonium salt compound to produce a color when heated, the heat-sensitive recording layer contains the diazonium salt compound and the coupler. A basic substance or the like that accelerates the color forming reaction is preferably added.

The diazonium salt compounds are compounds represented by the following general formula (B), and their maximum absorption wavelength can be controlled by the position and type of the substituent of the Ar moiety. Formula _{(B): Ar-N 2} + X - In the general formula (B), Ar represents an aryl group. X ⁻ represents an acid anion.

Specific examples of the diazonium salt compound include 4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4-dioctylaminobenzenediazonium, 4
-(N- (2-ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium, 4-N-ethyl-N-
Hexadecylamino-2-ethoxybenzodiazonium, 3-chloro-4-dioctylamino-2-octyloxyobenzenediazonium, 2,5-dibutoxy-
4-morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-
Dibutoxy-4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzene Diazonium, 2,5-dibutoxy-4-tolylthiobenzenediazonium, 3- (2-octyloxyethoxy) -4-
Examples thereof include acid anion salts such as morpholinobenzenediazonium and the following diazonium salt compounds (D-1 to 5). These may be used alone or in combination of two or more. Among these, hexafluorophosphate salts, tetrafluoroborate salts, 1,5-
Naphthalene sulfonate salts are particularly preferred.

[0072]

[Chemical 6]

Among these diazonium salt compounds,
Photodecomposes by light with a wavelength of 300 to 400 nm, 4-
(N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4
-Dioctylaminobenzenediazonium, 4- (N-
(2-Ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium, 4-N-ethyl-N-hexadecylamino-2-ethoxybenzodiazonium, 2,5
-Dibutoxy-4- (N- (2-ethylhexanoyl))
Piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, the diazonium salts shown in Specific Examples D-3 to 5 above. Compounds are particularly preferred. The maximum absorption wavelength of the diazonium salt compound here is measured by a spectrophotometer (Shimazu MPS-2000) prepared by coating each diazonium compound at a coating amount of 0.1 to 1.0 g / m ^2. It was done.

Examples of couplers that develop a color by reacting with the diazonium salt compound under heat include resorcin, flurglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, and 1-hydroxy-2-naphthoic acid morpholinopropylamide. 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-
Naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyloxypurupyramide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, Benzoylacetanilide, 2-chloro-5-octylacetoacetanilide,
1-phenyl-3-methyl-5-pyrazolone, 1-
(2'-octylphenyl) -3-methyl-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl)
-3-benzamido-5-pyrazolone, 1- (2 ',
4 ', 6'-trichlorophenyl) -3-anilino-5
-Pyralone, 1-phenyl-3-phenylacetamido-5-pyrazolone, compounds shown in the following (C-1 to 6),
And so on. These couplers may be used alone or in combination of two or more.

[0075]

[Chemical 7]

[0076]

[Chemical 8]

The basic substance is not particularly limited and may be appropriately selected from known ones depending on the purpose. In addition to inorganic or organic basic compounds, alkaline substances that cause decomposition or the like when heated are used. Releasing compounds are also included, and typical examples thereof include organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, and indoles. , Imidazoles, imidazolines, triazoles, morpholines,
Examples thereof include nitrogen-containing compounds such as piperidines, amidines, formazines and pyridines.

Specific examples thereof include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allylurea, thiourea,
Methylthiourea, allylthiourea, ethylenethiourea,
2-benzylimidazole, 4-phenylimidazole, 2-phenyl-4-methylimidazole, 2-undecylimidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-
2-imidazoline, 2-phenyl-2-imidazoline,
1,2,3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetate, N, N '
-Dibenzylpiperazine, 4,4'-dithiomorpholine, morpholinium trichloroacetate, 2-aminobenzothiazole, 2-benzoylhydrazinobenzothiazole and the like can be mentioned. These may be used alone or in combination of two or more.

The electron donating colorless dye is not particularly limited and may be appropriately selected from known ones according to the purpose. In the present invention, an electron donating colorless dye precursor can be used. .

Examples of the electron-donating colorless dye precursor include
For example, triarylmethane compounds, diphenylmethane compounds, thiazine compounds, xanthene compounds,
Examples include spiropyran compounds. They are,
One kind may be used alone, or two or more kinds may be used in combination. Among these, a triarylmethane compound and a xanthene compound are preferable from the viewpoint of high color density and usefulness. Examples of these are 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (ie, crystal violet lactone), 3,3-bis (p
-Dimethylamino) phthalide, 3- (p-dimethylaminophenyl) -3- (1,3-dimethylindole-3)
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (o-methyl-p-diethylaminophenyl)
-3- (2-methylindol-3-yl) phthalide,
4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenyl leuco auramine, N
-2,4,5-trichlorophenyl leuco auramine,
Rhodamine-B-anilinolactam, Rhodamine (p-
Nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam,

2-benzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethyl Aminofluorane, 2-anilino-3-methyl-6-isoamylethylaminofluorane, 2-
(O-chloroanilino) -6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-2-diethylaminofluorane, 2-anilino-3-chloro-6
-Diethylaminofluorane, benzoyl leuco methylene blue, p-nitrobenzyl leuco methylene blue,
3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-
Dinaphthopyran, 3-benzylspirodinaphthopyran,
3-propyl-spiro-dibenzopyran, and the like.

Examples of the electron accepting compound include phenol derivatives, salicylic acid derivatives, hydroxybenzoic acid esters and the like. Among these, bisphenols and hydroxybenzoic acid esters are particularly preferable, and specifically, 2,2-bis (p-hydroxyphenyl) propane (that is, bisphenol A) and 4,4′-
(P-Phenylenediisopropylidene) diphenol (ie, bisphenol P), 2,2-bis (p-hydroxyphenyl) pentane, 2,2-bis (p-hydroxyphenyl) ethane, 2,2-bis (p -Hydroxyphenyl) butane, 2,2-bis (4'-hydroxy-
3 ', 5'-dichlorophenyl) propane, 1,1-
(P-Hydroxyphenyl) cyclohexane, 1,1-
(P-Hydroxyphenyl) propane, 1,1- (p-
Hydroxyphenyl) pentane, 1,1- (p-hydroxyphenyl) -2-ethylhexane, 3,5-di (α
-Methylbenzyl) salicylic acid and its polyvalent metal salts,
3,5-di (tert-butyl) salicylic acid and its polyvalent metal salt, 3-α, α-dimethylbenzylsalicylic acid and its polyvalent metal salt, butyl p-hydroxybenzoate, p
-Benzyl hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol, p
-Cumylphenol and the like are particularly preferred.

In the present invention, the heat-sensitive recording layer preferably contains a sensitizer, and the sensitizer has a low aromatic group and a polar group in the molecule. An organic compound having a melting point is preferable, and specifically, benzyl p-benzyloxybenzoate, α-naphthylbenzyl ether,
β-naphthylbenzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p-chlorobenzyl) ether, 1,4-butanediol phenyl ether,
1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m-methylphenyl ether, 1-phenoxy-2- (p-tolyloxy) Ethane, 1-phenoxy-2- (p-ethylphenoxy)
Examples thereof include ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane, p-benzylbiphenyl, and the like.

The heat-sensitive recording layer preferably contains the compound represented by the following general formula (A) in an amount of 0.05 g / m ² or more. When the heat-sensitive recording layer is composed of a plurality of layers, the layer containing the compound represented by formula (A) is not particularly limited and can be appropriately selected according to the purpose.
It is preferably a layer composed of a solid dispersion.

General formula (A): R-SO ₃ M

In the above general formula (A), R represents an alkyl group, an aryl group, an alkoxyl group, an aryloxy group, a polyoxyethylene aryl group, or a polyoxyethylene alkyl group, and has 1 to 20 carbon atoms. A group is preferable, an aryl group having 1 to 30 carbon atoms is preferable, an alkoxyl group having 1 to 20 carbon atoms is preferable, an aryloxy group having 1 to 30 carbon atoms is preferable, and
A polyoxyethylene aryl group having 30 is preferable, and a polyoxyethylene alkyl group having 1 to 20 carbon atoms is preferable. M represents an alkali metal, and sodium, potassium and the like are preferable.

Specific examples of the compound represented by the general formula (A) include sodium lauryl sulfate, sodium higher alcohol sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, and alkyldiphenyletherdisulfonic acid. Sodium, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium alkane sulfonate, sodium salt of β-naphthalene sulfonic acid formalin condensate, special aromatic sulfonic acid formalin Sodium salt of a condensate, etc. are mentioned. These may be used alone or in combination of two or more. In the present invention, among these, sodium dodecylbenzenesulfonate represented by the following formula is preferable because it can improve the exposure coloration of the background part.

[0088]

[Chemical 9]

The content of the compound represented by the general formula (A) in the thermosensitive recording layer is 0.05 g / m ^2.
It is above, and 0.05 to 0.50 g / m ² is preferable,
It is preferably 0.05 to 0.20 g / m ² . When the content is less than 0.05 g / m ² , the heat resistance of the heat-sensitive recording material is not sufficient and the background exposure coloration is not preferable, while when it is 0.05 g / m ² , This is preferable because the weather resistance of the heat-sensitive recording material is remarkably improved and the background light exposure coloring is effectively suppressed.

In the heat-sensitive recording layer, the diazonium salt compound, the coupler that reacts with the diazonium salt compound to produce a color when heated, the basic substance, the electron-donating colorless dye, the electron-accepting compound, and the additive. There is no particular limitation on the mode of containing the sensitizer and the like, and it can be appropriately selected according to the purpose. For example, (1) a solid dispersion method and (2) an emulsification dispersion method. , (3) a method of incorporating by polymer dispersion,
(4) Method of incorporating by latex dispersion, (5) Method of incorporating by microcapsule, and the like.

Among these, from the viewpoint of storage stability, a method of microencapsulating the microcapsules is preferable. When utilizing a color-forming reaction between the diazonium salt compound and the coupler, the diazonium salt compound is microencapsulated. It is preferably contained in the heat-sensitive recording layer. When the color-forming reaction between the electron-donating colorless dye and the electron-accepting compound is used, the electron-donating colorless dye is microencapsulated to form the heat-sensitive recording layer. It is preferable to contain it.

When the thermosensitive recording layer has a multilayer structure, a multicolor thermosensitive recording material can be obtained by changing the hue of each thermosensitive recording layer. In this case, the layer structure is
It is not particularly limited and may be appropriately selected depending on the intended purpose. In the present invention, two diazonium salt compounds having different photosensitizing wavelengths react with each diazonium salt compound under heat to develop different hues. It is preferable to form a multicolor heat-sensitive recording layer by laminating two heat-sensitive recording layers in which a coupler is combined and a heat-sensitive recording layer in which an electron-donating colorless dye and an electron-accepting compound are combined. That is, a thermosensitive recording layer A containing an electron-donating colorless dye and an electron-accepting compound on the support, a diazonium salt compound having a maximum absorption wavelength of 360 ± 20 nm, and a reaction with the diazonium salt compound during thermal exposure. A heat-sensitive recording layer B-1 containing a coupler for coloring, a heat-sensitive recording layer B-containing a diazonium salt compound having a maximum absorption wavelength of 400 ± 20 nm, and a coupler which reacts with the diazonium salt compound to develop a color. A multicolor thermosensitive recording material in which 2 is laminated in this order is preferable.

As a recording method of this multicolor heat-sensitive recording material, first, the heat-sensitive recording layer B-2 is heated and then the heat-sensitive recording layer B-
The diazonium salt compound contained in 2 and the coupler are colored. Next, after irradiating with light of 400 ± 20 nm to decompose the unreacted diazonium salt compound contained in the heat-sensitive recording layer B-2, sufficient heat is developed for the heat-sensitive recording layer B-1 to develop color. In addition, the diazonium salt compound and the coupler contained in the thermosensitive recording layer B-1 are allowed to develop color. At this time, the heat-sensitive recording layer B-2 is also strongly heated at the same time, but since the diazonium salt compound has already been decomposed and the color forming ability has been lost, no color is formed. Further, the diazonium salt compound contained in the thermosensitive recording layer B-1 is decomposed by irradiating with light of 360 ± 20 nm, and finally, sufficient heat for the thermosensitive recording layer A to develop color is applied to develop the color. At this time, the thermal recording layer B-
2 and the heat-sensitive recording layer B-1 are also heated strongly at the same time, but the diazonium salt compound is already decomposed and the color forming ability is lost, so that no color is formed.

Further, in the present invention, a three-layer thermosensitive recording layer comprising a combination of three kinds of diazonium salt compounds having different photosensitizing wavelengths and a coupler which reacts with each of the diazonium salt compounds to form a different hue when heated is provided. It is also preferable to form a laminated multicolor heat-sensitive recording layer. That is, the maximum absorption wavelength on the support is 350 nm or less, preferably 34 nm or less.
Thermosensitive recording layer A-1 containing a diazonium salt compound having a size of 0 nm or less and a coupler that reacts with the diazonium salt compound to produce a color, and the maximum absorption wavelength is 360 ± 20 nm.
A thermosensitive recording layer A-2 containing a diazonium salt compound which is a compound and a coupler which reacts with the diazonium salt compound to produce a color when heated, a diazonium salt compound having a maximum absorption wavelength of 400 ± 20 nm, the diazonium salt compound and a heat Thermosensitive recording layer A-3 containing a coupler that reacts with time to develop a color
A multicolor thermosensitive recording material in which the above are laminated in this order is preferable.

In the case of the above multicolor heat-sensitive recording layer,
If the coloring hue of each heat-sensitive recording layer is selected to be the three primary colors in subtractive color mixing, yellow, magenta, and cyan,
Full-color image recording is possible.

(Microcapsule) When the diazonium salt compound, the electron-donating colorless dye precursor, or the compound represented by the general formulas (2) to (5) is microencapsulated, the microencapsulation method is used. As the above, a conventionally known method can be used. For example, the diazonium salt compound, the electron-donating colorless dye precursor, or the compounds represented by the general formulas (2) to (5) and the microcapsule wall precursor are sparingly soluble or insoluble in water in an organic solvent. By dissolving it in an aqueous solution of a water-soluble polymer, emulsifying and dispersing using a homogenizer, etc., and raising the temperature to form a wall film at the oil / water interface of the polymer substance to be the microcapsule wall, Microcapsules of the diazonium salt compound, the electron-donating colorless dye precursor, or the compounds represented by the general formulas (2) to (5) can be prepared.

Specific examples of the microcapsule wall film include, for example, polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin, styrene-acrylate copolymer resin, and styrene. Examples of the wall film include an ethylene-methacrylate copolymer resin, gelatin, polyvinyl alcohol, and the like. Among these, a wall film made of polyurethane / polyurea resin is preferable.

The microcapsules having a wall film made of the polyurethane / polyurea resin are prepared by mixing a microcapsule wall precursor such as polyisocyanate with a core substance to be microencapsulated, and then adding a water-soluble highly soluble material such as polyvinyl alcohol. It is produced by emulsifying and dispersing it in an aqueous solution of molecules and raising the liquid temperature to cause a polymer formation reaction at the oil droplet interface.

Specific examples of the polyvalent isocyanate compound include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate and diphenylmethane-. 4,
4'-diisocyanate, 3,3'-diphenylmethane-4,4'-diisocyanate, xylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2- Diisocyanates such as diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, toluene-2, Triisocyanates such as 4,6-triisocyanate, tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, hexamethylene diisocyanate and triisocyanate Adduct of trimethylolpropane,
An isocyanate prepolymer such as an adduct of 2,4-tolylene diisocyanate and trimethylolpropane, an adduct of xylylene diisocyanate and trimethylolpropane, an adduct of tolylene diisocyanate and hexanetriol, and the like can be given. These may be used alone or in combination of two or more, and among these, those having three or more isocyanate groups in the molecule are particularly preferable.

In the above microencapsulation method,
The diazonium salt compound, or the general formula (2) to
As the organic solvent in which the compound represented by (5) is dissolved, the oil described in the above emulsification and dispersion method can be used. The same applies to water-soluble polymers.

The average particle size of the microcapsules is preferably 0.1 to 1.0 μm, more preferably 0.2 to 0.7 μm.
m is more preferred.

(Support) As the support, for example,
Polyester film such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative film such as cellulose triacetate film, polystyrene film, polypropylene film, polyolefin film such as polyethylene film, polyimide film, polyvinyl chloride film, polyvinylidene chloride film,
Examples include plastic films such as polyacrylic acid copolymer film and polycarbonate film, paper, synthetic paper, paper having a plastic resin layer, and the like, and the support having the plastic film layer is preferable. These may be transparent or opaque, and may be used alone or in combination of two or more.

Suitable examples of the support having the plastic layer include those having a thermoplastic resin layer formed on both sides of the base paper or at least on the side where the recording layer is formed. For example, (1) A base paper on which a thermoplastic resin is melt-extrusion coated, (2) A base paper on which a gas barrier layer is applied on a melt-extrusion-coated thermoplastic resin,
(3) Plastic paper with low oxygen permeability of the base paper adhered, (4) Thermoplastic resin provided by melt extrusion on the surface of the plastic film adhered to the base paper, (5) Thermoplastic base paper Examples include those obtained by melt extrusion coating a resin and then adhering a plastic film thereto.

Examples of the thermoplastic resin melt-extruded onto the base paper include ethylene, olefin polymers such as homopolymers of α-olefins such as polyethylene and polypropylene, and mixtures of these various polymers, and ethylene. Preferable examples include random copolymers with vinyl alcohol. Examples of the polyethylene include LDPE
(Low density polyethylene), HDPE (high density polyethylene), L-LDPE (linear low density polyethylene) and the like.

The method for adhering the plastic film to the base paper is not particularly limited and may be appropriately selected from known lamination methods as described in "New Laminating Manual" edited by the Processing Technology Research Group. Suitable examples include so-called dry lamination, solventless dry lamination, dry lamination using an electron beam or ultraviolet curable resin, and hot dry lamination. In the present invention, among the above-mentioned supports, a base paper containing natural pulp as a main component and coated on both sides with an olefin polymer is particularly preferable.

(Antioxidant) In the invention, in order to further improve the light resistance, the following known antioxidants can be added to the heat-sensitive recording material. Examples of such antioxidants include European Patent No. 310551 and German Patent No. 3435443.
Japanese Patent Publication, European Patent Publication No. 310552, Japanese Patent Laid-Open No. 3-121449, European Patent Publication No. 4
59416, JP-A-2-262654, JP-A-2-71262, JP-A-63-163351.
U.S. Pat. No. 4,814,262, JP-A-54
-48535, JP-A-5-61166, JP-A-5-119449, and U.S. Pat. No. 4980.
275, JP-A-63-113536, JP-A-6-
No. 2-262047, European Published Patent No. 223
The antioxidants and the like described in JP 739, European Patent Publication 309402, European Patent Publication 309401 and the like can be mentioned, and specifically, the following can be mentioned.

[0107]

[Chemical 10]

[0108]

[Chemical 11]

[0109]

[Chemical 12]

[0110]

[Chemical 13]

[0111]

[Chemical 14]

[0112]

[Chemical 15]

[0113]

[Chemical 16]

[0114]

[Chemical 17]

Further, Japanese Patent Laid-Open No. 60-125470,
JP-A-60-125471, JP-A-60-125
472, JP 60-287485, JP 60-287486, and JP 60-28748.
7, JP 62-146680 A, JP 6
0-287488, JP-A-62-282885, JP-A-63-89877, and JP-A-63-8.
8380, JP-A-63-088831, JP-A-01-239282, and JP-A-04-2916.
No. 85, No. 04-291684, No. 05-1888687, No. 05-188686.
Japanese Patent Laid-Open No. 05-110490, Japanese Patent Laid-Open No. 05-110490
-1108437, JP-A-05-170361, JP-A-63-203372, JP-A-63-
224989, JP-A-63-267594, JP-A-63-182484, JP-A-60-1.
07384, JP-A-60-107383,
JP-A-61-160287, JP-A-61-185
483, JP 61-211079, JP 63-251282, and JP 63-05117.
Japanese Patent Publication No. 4 and Japanese Patent Publication No. 043294, Japanese Patent Publication No.
The antioxidants described in JP-A-8-033212 and the like can be mentioned.

Specific examples include 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-hydroxyphenylpropane, 1,1-bis-4
-Hydroxyphenyl-2-ethylhexane, 2-methyl-4-methoxy-diphenylamine, 1-methyl-2
-Phenylindole and the like.

These antioxidants are used for the heat-sensitive recording layer,
It can be added to the intermediate layer, the light transmittance adjusting layer, and the protective layer.

[0118]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified.

[Example 1] <Preparation of phthalated gelatin solution> Phthalated gelatin (trade name; MGP gelatin, manufactured by Nibbi Collegn Ltd.) 3
2 parts, 1,2-benzothiazolin-3-one (3.5%
Methanol solution, Daito Chemical Industry Co., Ltd. 0.914
3 parts and 367.1 parts of ion-exchanged water were mixed and dissolved at 40 ° C. to obtain a phthalated gelatin aqueous solution.

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

(1) Yellow thermosensitive recording layer coating liquid (a)
Preparation <Diazonium salt compound-encapsulating microcapsule liquid (a)
Preparation of> In 16.1 parts of ethyl acetate, 2.2 parts of the following diazonium salt compound (A) (maximum absorption wavelength 420 nm) and the following diazonium salt compound (B) (maximum absorption wavelength 420n)
m) 2.2 parts, monoisopropyl biphenyl 4.8 parts,
4.8 parts of diphenyl phthalate and diphenyl- (2,
4,6-Trimethylbenzoyl) phosphine oxide (trade name; Lucillin TPO, BASF Japan Ltd.)
(Manufactured by Mitsui Chemical Co., Ltd.) 0.4 part was added and the mixture was heated to 40 ° C. and uniformly dissolved. A mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the obtained mixed liquid (trade name; Takenate D119N (50% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd. )) Was added and stirred uniformly to obtain a mixed solution (I).

[0122]

[Chemical 18]

Separately, 50 parts of the above phthalated gelatin aqueous solution was added to 16.3 parts of ion-exchanged water and ScrapH (AG-8).
(50%) manufactured by Nippon Seika Co., Ltd. (0.34 parts) was added to obtain a mixed solution (II). The mixed solution (I) was added to the mixed solution (II), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 20 water is added to the obtained emulsion.
After adding parts to homogenize, the mixture was stirred at 40 ° C., and an encapsulation reaction was carried out for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corporation) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corporation) were added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin is removed by filtration, and the concentration of the solid content of the capsule liquid is adjusted to 20.0%, and the diazonium salt compound-encapsulating microcapsule liquid (a) is added.
Got The particle size of the obtained microcapsules was measured by a particle size measurement (LA-700, measured by Horiba Ltd.),
The median diameter was 0.36 μm.

<Preparation of coupler compound emulsion (a)> The following coupler compound (C) 9.9 was added to 33.0 parts of ethyl acetate.
Part, triphenylguanidine (Hodogaya Chemical Co., Ltd.)
9.9 parts, 4,4 '-(m-phenylene diisopropylidene) diphenol (trade name; bisphenol M, Mitsui Petrochemical Co., Ltd.) 20.8 parts, 4- (2-ethylhexyloxy) benzene Sulfonamide (Manac Co., Ltd.
13.6 parts, 4-n-pentyloxy benzene sulfonic acid amide (manufactured by Manac Co., Ltd.) 6.8 parts, calcium dodecyl benzene sulfonate (trade name Pionine A-4)
1-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) 4.
Two parts were dissolved to obtain a mixed solution (III).

[0125]

[Chemical 19]

Separately, the above alkali-treated gelatin aqueous solution 20
Ion-exchanged water (107.3 parts) was mixed with 6.3 parts to obtain a mixed solution (IV). The mixed solution (III) was added to the mixed solution (IV), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The resulting coupler compound emulsion was depressurized and heated to remove ethyl acetate, and then the concentration was adjusted so that the solid concentration was 26.5%. The particle size of the obtained coupler compound emulsion was measured by particle size measurement (LA-7
00, measured by Horiba, Ltd.), and the median diameter was 0.21 μm. Furthermore, with respect to 100 parts of the above coupler compound emulsion, SBR latex (trade name SN-3
07,48% liquid, Sumika ABS Latex Co., Ltd.
(Manufactured by Mitsui Chemicals Co., Ltd.) having a concentration adjusted to 26.5% was added and uniformly stirred to obtain a coupler compound emulsion (a).

<Preparation of coating liquid (a)> The mass ratio of coupler compound / diazo compound in which the above-mentioned microcapsule liquid containing a diazonium salt compound (a) and the above-mentioned coupler compound emulsion (a) are contained is 2. The mixture was mixed at a ratio of 2/1 to obtain a yellow thermosensitive recording layer coating liquid (a).

(2) Preparation of magenta thermosensitive recording layer liquid <diazonium salt compound-encapsulating microcapsule liquid (b)
Preparation of ## STR00003 ## 2.8 parts of the following diazonium salt compound (D) (maximum absorption wavelength 365 nm), 1.9 parts of diphenyl phthalate, 3.9 parts of phenyl 2-benzoyloxybenzoic acid ester, and 15.1 parts of ethyl acetate. Compound (E) below
(Product name: Light Ester TMP, Kyoei Yushi Kagaku Co., Ltd.)
4.2 parts) and 0.1 parts of calcium dodecylbenzene sulfonate (trade name: Pionin A-41-C 70% methanol solution, Takemoto Yushi Co., Ltd.) were added and heated to uniformly dissolve. A mixture of a xylylene diisocyanate / trimethylol propane adduct and a xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the above mixture (trade name: Takenate D119N (50
% Ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) 2.5 parts and xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) 6.8 parts was added and stirred uniformly to obtain a mixed solution (V).

[0129]

[Chemical 20]

Separately, the phthalated gelatin aqueous solution 55.
21.0 parts of ion-exchanged water was added to 3 parts and mixed to obtain a mixed solution (VI). Add the mixed solution (V) to the mixed solution (VI),
4 using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.)
It was emulsified and dispersed at 0 ° C. After 24 parts of water was added to the obtained emulsion and the mixture was homogenized, the mixture was stirred at 40 ° C. and the encapsulation reaction was carried out for 3 hours while removing ethyl acetate. After this, ion exchange resin Amberlite IRA68 (Organo Corporation)
4.1 parts, Amberlite IRC50 (organo)
(Manufactured by K.K.) 8.2 parts was added, and the mixture was further stirred for 1 hour. Then, the ion exchange resin was removed by filtration, and the concentration of the solid content of the capsule liquid was adjusted to 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (b).
The particle size of the obtained microcapsules was measured by a particle size measurement (LA-7
00, measured by Horiba, Ltd.), and the median diameter was 0.43 μm.

<Preparation of coupler compound emulsion (b)> The following coupler compound (F) was added to 36.9 parts of ethyl acetate.
9 parts, triphenylguanidine (Hodogaya Chemical Co., Ltd.)
14.0 parts, 4,4 '-(m-phenylene diisopropylidene) diphenol (trade name; bisphenol M, Mitsui Petrochemical Co., Ltd.) 14.0 parts, 1,1- (p-
14 parts of hydroxyphenyl) -2-ethylhexane,
3,3,3 ', 3'-tetramethyl-5,5'6,6'
-Tetra (1-propoxy) -1,1'-spirobisindane 3.5 parts, the following compound (G) 3.5 parts, tricresyl phosphate 1.7 parts, diethyl maleate 0.8 parts, dodecyl benzene sulfone Calcium acid (trade name: Pionin A-41-C 70% methanol solution, Takemoto Yushi Co., Ltd.)
(Manufactured by Mfg. Co., Ltd.) was dissolved to obtain a mixed solution (VII).

[0132]

[Chemical 21]

Separately, the above gelatin aqueous solution for emulsion preparation 20
Ion-exchanged water (107.3 parts) was mixed with 6.3 parts to obtain a mixed solution (VIII). The mixed solution (VII) was added to the mixed solution (VIII), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The obtained coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration was 24.5% to obtain a coupler compound emulsion (b). The particle size of the obtained coupler compound emulsion was measured by particle size measurement (LA-700, Horiba Seisakusho).
(Measured by Co., Ltd.), the median diameter was 0.22 μm.

<Preparation of coating liquid (b)> The mass ratio of coupler compound / diazo compound encapsulating the microcapsule liquid (b) encapsulating the diazonium salt compound and the emulsion emulsion (b) of the coupler compound is 3. Mix to 5/1. Further, a polystyrene sulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) was added to the capsule liquid volume 10
The mixture was mixed so as to be 0.2 part with respect to 1 part to obtain a magenta thermosensitive recording layer coating liquid (b).

(3) Preparation of cyan thermosensitive recording layer liquid <electron donating dye precursor encapsulated microcapsule liquid (c)
Preparation of> In 18.1 parts of ethyl acetate, 7.6 parts of the following electron-donating dye (H), 1-methylpropylphenyl-phenylmethane and 1- (1-methylpropylphenyl)-
2-phenylethane mixed solution (trade name; Hysol SA
8.0 parts of S-310, manufactured by Nippon Oil Co., Ltd., and 8.0 parts of the following compound (I) (trade name; trade name of Irgaperm 2140 Ciba-Geigy Co., Ltd.) were added and heated to uniformly dissolve. Xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) 7.2 parts as a capsule wall material in the above mixture and polymethylene polyphenyl polyisocyanate (Product name: Millionate MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.) 1
0.6 part was mixed and stirred uniformly to obtain a mixed solution (IX).

[0136]

[Chemical formula 22]

Separately, the phthalated gelatin aqueous solution 28.
8 parts of ion-exchanged water 9.5 parts, ScrapH AG-8
(50%) Nippon Seika Co., Ltd. 0.17 parts and sodium dodecylbenzene sulfonate (10% aqueous solution) 4.
3 parts were added and mixed to obtain a mixed solution (X). Mixture (X)
The mixed liquid (IX) was added to the mixture, and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 50 parts of water and tetraethylenepentamine of 0.
12 parts were added and homogenized, the mixture was stirred at 65 ° C. and the ethyl acetate was removed for 3 hours to carry out an encapsulation reaction, and the solid content concentration of the capsule solution was adjusted to 33% to obtain a microcapsule solution. . The particle size of the obtained microcapsules was measured (measured by LA-700, manufactured by Horiba Ltd.)
As a result, the median diameter was 1.00 μm. Furthermore, with respect to 100 parts of the microcapsule solution, 3.7 parts and 4,4 ′ of 25% sodium dodecylbenzenesulfonate aqueous solution (trade name; Neoperex F-25, manufactured by Kao Corporation).
-Bistriazinylaminostilbene-2,2'-disulfone derivative (trade name; Kaycall BXNL, manufactured by Nippon Soda Co., Ltd.) was added and uniformly stirred to obtain a microcapsule dispersion (c).

<Preparation of Electron Accepting Compound Dispersion Liquid (c)>
7. To the above phthalated gelatin aqueous solution 11.3 parts, ion-exchanged water 30.1 parts, 4,4 '-(p-phenylenediisopropylidene) diphenol (trade name; bisphenol P, manufactured by Mitsui Petrochemical Co., Ltd.) 8. 5 parts, 3.8 parts of 2% -2-ethylhexyl sodium succinate aqueous solution was added, and the mixture was dispersed overnight in a ball mill to obtain a dispersion liquid. The solid content concentration of this dispersion was 26.6%. After adding 45.2 parts of the alkali-treated gelatin aqueous solution to 100 parts of the above dispersion and stirring for 30 minutes, the solid content concentration of the dispersion was 23.5.
Ion-exchanged water was added so that the amount became 100% to obtain an electron-accepting compound dispersion liquid (c).

<Preparation of coating liquid (c)> The above-mentioned microcapsule liquid (c) containing an electron-donating dye precursor in the interior and the above-mentioned electron-accepting compound dispersion liquid (c) were used as an electron-accepting compound / electron-donating dye precursor Were mixed so that the mass ratio was 10/1 to obtain a cyan thermosensitive recording layer coating liquid (c).

(4) Preparation of coating liquid for intermediate layer Alkali-treated low ionic gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.) 100.0 parts, 1,2-benzothiazolin-3-one ( 3.5% methanol solution,
2.857 parts of Daito Chemical Industry Co., Ltd.), 0.5 parts of calcium hydroxide, 521.643 parts of ion-exchanged water are mixed,
It melted at 50 ° C. to obtain an aqueous gelatin solution for preparing an intermediate layer. 10.0 parts of the aqueous gelatin solution for preparing the intermediate layer, (4
-Sodium nonylphenoxytrioxyethylene) butyl sulfonate (2.0% aqueous solution manufactured by Sankyo Chemical Co., Ltd.)
0.05 part, boric acid (4.0% aqueous solution) 1.5 parts, polystyrene sulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%) 0.19 part, 4% aqueous solution of the following compound (J) (Wako Pure Chemical Industries, Ltd.) 4.53 parts, ion-exchanged water 0.67
The parts were mixed to obtain a coating liquid for the intermediate layer.

[0141]

[Chemical formula 23]

(5) Preparation of coating liquid for light transmittance adjusting layer <Preparation of UV absorber precursor microcapsule liquid> 200 parts of ethyl acetate was used as a UV absorber precursor [2-allyl-6- (2H-benzo Triazol-2-yl) -4
-T-octylphenyl] benzenesulfonate 46
Part, 2,5-di-t-octylhydroquinone (trade name: AF317) 16 parts, tricresyl phosphate 6 parts, α-
Methyl styrene dimer (trade name: MSD-100, manufactured by Mitsui Chemicals, Inc.) 19 parts, calcium dodecylbenzene sulfonate (trade name: Pionin A-41-C (70% methanol solvent), manufactured by Takemoto Yushi Co., Ltd.) 1.6 parts were uniformly dissolved. 94 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the above mixture as a capsule wall material, and the mixture was uniformly stirred and ultraviolet rays were added. An absorbent precursor mixed solution (VII) was obtained.

Separately, 3 parts were added to 52 parts of itaconic acid-modified polyvinyl alcohol (trade name: KL-318, manufactured by Kuraray Co., Ltd.).
PV for UV absorber precursor microcapsule liquid by mixing 8.9 parts of 0% phosphoric acid aqueous solution and 532.6 parts of ion-exchanged water
A aqueous solution was prepared. The ultraviolet absorber precursor mixture (VII) was added to 1155 parts of the PVA aqueous solution for the ultraviolet absorber precursor microcapsule liquid, and the mixture was emulsified and dispersed at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). did. After adding 450 parts of ion-exchanged water to the obtained emulsion and homogenizing it, the encapsulation reaction was carried out for 3 hours while stirring at 40 ° C. After this, ion exchange resin Amberlite M
100 parts of B-3 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Then, the ion-exchange resin was removed by filtration, and the concentration of the solid content of the capsule liquid was adjusted to 13%. The particle size of the obtained microcapsules was measured by the particle size measurement (LA
-700, measured by Horiba Ltd.), and the median diameter was 0.23 ± 0.05 μm. In 1244 parts of this capsule liquid, silica-modified polyvinyl alcohol (trade name: R-1130, manufactured by Kuraray Co., Ltd., saponification degree 98
%) 10% aqueous solution 793 parts, carboxy-modified styrene butadiene latex (trade name: SN-307, (48
% Aqueous solution) and 3.9 parts of Sumitomo Nogatac Co., Ltd.) were mixed to obtain an ultraviolet absorber precursor microcapsule liquid.

<Preparation of Coating Solution for Light Transmittance Adjustment Layer> 1000 parts of the above UV absorber precursor microcapsule solution was added to 296.4 parts of ion-exchanged water, 15.0 parts of 4% aqueous sodium hydroxide solution, and (4- Nonylphenoxytrioxyethylene) sodium butyl sulfonate (Sankyo Chemical Co., Ltd.,
A 2.0% aqueous solution) (51.36 parts) was mixed to obtain a coating liquid for a light transmittance adjusting layer. The content of the silica-modified polyvinyl alcohol (trade name: R-1130, manufactured by Kuraray Co., Ltd., saponification degree: 98%) was 30% by mass of the light transmission adjusting layer. The coating solution was applied to form a dry film, and the oxygen permeability was measured to be 0.52.

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

<Preparation of Pigment Dispersion Liquid for Protective Layer> Barium sulfate (trade name; BF-21F, barium sulfate content 93%)
As described above, in 8 parts of Sakai Chemical Industry Co., Ltd., an anionic special polycarboxylic acid type polymer activator (trade name: Poise 532A (4
0% aqueous solution), Kao Co., Ltd.) 0.2 parts, ion-exchanged water 1
1.8 parts were mixed and dispersed with Dynomill to prepare a barium sulfate dispersion liquid. This dispersion was measured for particle size (LA-9
As a result of No. 10, carried out by Horiba, Ltd.), the median diameter was 0.15 μm or less. Barium sulfate dispersion 4
To 5.6 parts, 8.1 parts of colloidal silica (trade name: Snowtex O (20% aqueous dispersion), manufactured by Nissan Kagaku Co., Ltd.) was added to obtain a pigment dispersion for a protective layer.

<Preparation of Matting Agent Dispersion for Protective Layer> Wheat starch (trade name; wheat starch S, Shinshin Food Industry Co., Ltd.) 220
Aqueous dispersion of 1-2 benzisothiazoline 3-one (trade name: PROXEL BD, manufactured by ICI Co., Ltd.)
3.81 parts, deionized water 1976.19 parts are mixed,
It was uniformly dispersed to obtain a protective layer matting agent dispersion.

<Preparation of Coating Blend Solution for Protective Layer> 1000 parts of the polyvinyl alcohol solution for the protective layer was mixed with the compound (K) (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink and Chemicals, Inc.). ) 40 parts, (4-nonylphenoxytrioxyethylene) sodium butylsulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution) 50 parts, 49.87 parts of the pigment dispersion liquid for the protective layer, the protective layer Matting agent dispersion 16.65 parts, zinc stearate dispersion (trade name:
Hydrin F115, 20.5% aqueous solution, Chukyo Yushi Co., Ltd.
48.7 parts were uniformly mixed to obtain a coating liquid for coating a protective layer.

(7) Support with undercoat layer <Preparation of undercoat layer liquid> Enzyme-decomposed gelatin (average molecular weight:
10,000, PAGI viscosity: 1.5 mPa · s (15
40 parts of mP) and PAGI method jelly strength: 20 g) were added to 60 parts of ion-exchanged water and dissolved by stirring at 40 ° C. to prepare a gelatin aqueous solution for the undercoat layer. Separately water-swellable synthetic mica (Aspect ratio: 1000, Brand name: Somasif ME10
No. 0 (manufactured by Co-op Chemical Co., Ltd.) and 92 parts of water were mixed and wet-dispersed with Viscomill to obtain a mica dispersion having an average particle size of 2.0 μm. Water was added to this mica dispersion so that the mica concentration was 5%, and the mixture was uniformly mixed to prepare a desired mica dispersion.

40% gelatin aqueous solution of 40% at 40 ° C.
To 0 parts, add 120 parts of water and 556 parts of methanol,
After thoroughly stirring and mixing, 208 parts of 5% of the above mica dispersion was added, thoroughly mixed and stirred, and 9.8 parts of 1.66% polyethylene oxide-based surfactant was added. And the liquid temperature to 35
The coating solution for the undercoat layer (5.7%) was prepared by keeping 7.3 to 40 ° C. and adding 7.3 parts of a gelatin hardener for an epoxy compound to obtain a coating solution for the undercoat layer.

<Preparation of Support with Undercoat Layer> LBPS5
Wood pulp consisting of 0 parts and 50 parts LBPK was beaten by a disc refiner to a Canadian freeness of 300 ml, and 0.5 parts of epoxidized behenic acid amide, 1.0 part of anionic polyacrylamide, and aluminum sulfate 1.
0 part, polyamide polyamine epichlorohydrin 0.1
Parts and 0.5 parts of cationic polyacrylamide were added at an absolutely dry mass ratio to pulp, and a base paper having a basis weight of 114 g / m ² was made into paper by a Fourdrinier paper machine, and the thickness was adjusted to 100 μm by calendering.

Next, after corona discharge treatment was applied to both sides of the base paper, polyethylene was applied to a resin thickness of 36 using a melt extruder.
A resin layer composed of a matte surface was formed by coating so as to have a thickness of μm (this surface is called a back surface). Next, on the side opposite to the surface on which the above resin layer was formed, a melt extrusion machine was used to coat polyethylene containing 10% of anatase type titanium dioxide and a trace amount of ultramarine blue to a resin thickness of 50 μm. A layer was formed (this side is called the front side). After the corona discharge treatment on the polyethylene resin coated surface of the back side, aluminum oxide (trade name; alumina sol 100, Nissan Chemical Industries, Ltd.) was used as an antistatic agent.
Silicon dioxide (trade name: Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) = 1/2 (mass ratio) was dispersed in water and applied with a weight of 0.2 g / m ² after drying. . Next, the polyethylene resin-coated surface of the front surface was subjected to corona discharge treatment, and then the above undercoat liquid was applied so that the coating amount of mica was 0.26 g / m ² , to obtain a support with an undercoat layer.

(8) Application of coating liquid for each heat-sensitive recording layer On the support with the undercoat layer, from the bottom, the coating liquid (c) for the yellow heat-sensitive recording layer, the coating liquid for the intermediate layer, and the magenta heat-sensitive layer. The recording layer coating liquid (b), the intermediate layer coating liquid, the cyan thermosensitive recording layer coating liquid (a), the light transmittance adjusting layer coating liquid, and the protective layer coating liquid are continuously formed in seven layers in this order. Apply 30 ℃ humidity 30%, and 40 ℃ humidity 3
It was dried under the condition of 0% to obtain a multicolor heat-sensitive recording material of Example 1.

At this time, the coating amount of the coating liquid (a) for the heat-sensitive recording layer was the same so that the coating amount of the diazo compound (A) contained in the liquid was 0.078 g / m ^{2 in} terms of solid coating amount. The coating amount of the coating solution (b) for the heat-sensitive recording layer was 0.20 in terms of the coating amount of the solid content of the diazo compound (D) contained in the liquid.
Similarly, the coating amount of the coating liquid (c) for the thermosensitive recording layer is 6 g / m ² and the electron donating dye contained in the liquid.
Coating was performed so that the coating amount of (H) was 0.355 g / m ^{2 in} terms of solid coating amount. In addition, the coating liquid for the intermediate layer has a solid coating amount of 2.39 g / m between (a) and (b).
^{2. Between} the (b) and (c), the solid coating amount is 3.34 g.
/ M ² , the coating liquid for the light transmittance adjusting layer has a solid coating amount of 2.35 g / m ² , and the protective layer has a solid coating amount of 1.39 g.
The coating was carried out so as to be / m ² . The oxygen permeability of each layer is as shown in Table 1.

The multicolor heat-sensitive recording material thus obtained was measured at a wavelength of 4 using a weather meter (manufactured by Atlas, Ci65 type).
An exposure test was conducted by continuous irradiation for 48 hours and 96 hours under an artificial solar light source with an output of 20 nm of 0.9 w / cm ² . The yellow density of the obtained image is calculated by X-rite model
It was measured by 310 (X-rite, manufactured by Incorporated). The results are shown in Table 2.

Example 2 15.0 parts of an alkali-treated gelatin aqueous solution was used instead of 45.2 parts of the alkali-treated gelatin aqueous solution used in <Preparation of electron-accepting compound dispersion (c)> in Example 1. A multicolor heat-sensitive recording material of Example 2 was prepared in the same manner as in Example 1 except that the above-described preparation was performed, and the same evaluation was performed. The results are shown in Tables 1 and 2.

[Comparative Example 1] Silica-modified polyvinyl alcohol (trade name: R-11) used in <Preparation of UV absorber precursor microcapsule liquid> in Example 2
3, 793 parts of 10% aqueous solution of Kuraray Co., Ltd., saponification degree of 98%), carboxy-modified styrene butadiene latex (trade name: SN-307, (48% aqueous solution), Sumitomo Nogatak Co., Ltd.) 3. Carboxy modified styrene butadiene latex (trade name: SN-
307, (48% aqueous solution), Sumitomo Nogatak Co., Ltd.
A multicolor thermosensitive recording material of Comparative Example 1 was prepared in the same manner as in Example 2 except that 2.416 parts was used, and the same evaluation was made. The results are shown in Tables 1 and 2. [Comparative Example 2] A multicolor heat-sensitive recording material of Comparative Example 2 was produced in the same manner as in Example 2 except that the undercoat layer used in <Preparation of support with undercoat layer> in Example 2 was removed. The same evaluation was made. The results are shown in Tables 1 and 2.

[0158]

[Table 1]

[0159]

[Table 2]

As is clear from Table 2, in the heat-sensitive recording material of Comparative Example 1, the increase in the coloring density of the background due to light irradiation increases with time, whereas in the heat-sensitive recording material of Example 1, light irradiation The increase in the coloring density due to was lower than that in Comparative Example 1, and the background light exposure coloring could be effectively suppressed.

[0161]

According to the heat-sensitive recording material of the present invention, the light resistance is remarkably excellent and the background exposure coloring can be effectively suppressed.

Claims (2)

[Claims] 1. A heat-sensitive recording material having at least one heat-sensitive recording layer on a support, and at least one layer having an oxygen permeability of 0.7 or less is provided above and below the heat-sensitive recording layer. A heat-sensitive recording material characterized in that 2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer has an oxygen permeability of 10 or less.