JPH0645262B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "The present invention relates to an industrial heat-sensitive recording material, and more particularly to a fixable diazo heat-sensitive recording material.

"Prior Art" As a recording material used in a heat-sensitive recording method, a leuco color-forming heat-sensitive recording material is usually used. However, this heat-sensitive recording material has a drawback that color develops unexpectedly due to severe handling after recording, heating or adhesion of solvents, and the recorded image is stained. As a heat-sensitive recording material without such a defect, diazo color-developing heat-sensitive recording material has been actively researched in recent years. For example, JP-A-57-12
3086, The Institute of Image Electronics Engineers of Japan, 11 , 290 (198)
As disclosed in 2), etc., heat recording is performed on a recording material using a diazo compound, a coupling component and a basic component (including a substance that becomes basic by heat), and then light irradiation is not performed. It decomposes the diazo compound in the reaction to stop the color development. Certainly, according to this method, it is possible to stop (hereinafter, referred to as fixing) the color development of a portion where recording is unnecessary. However, also in this recording material, pre-coupling gradually progresses during storage, and undesired coloring (fog) may occur. For this reason, it has been attempted to prevent contact between the components and prevent pre-coupling by allowing any one of the coloring components to exist in the form of particles in a discontinuous state. The property (hereinafter referred to as raw storability) is not sufficient and the thermochromic property is deteriorated. As another measure, to minimize contact between the components,
It is known to separate the diazo compound and the coupling component as separate layers (for example, the above-mentioned JP-A-57-1).
23086). This method is not practical because the raw storability is satisfactorily improved, but the thermochromic property is largely lowered, and it cannot respond to high-speed recording with a short pulse width. Further, as a method for satisfying both the raw storability and the thermochromic property, either a coupling component or a basic substance is used as a non-polar wax-like substance (JP-A-57-44141 and JP-A-57-1426).
No. 36) or a hydrophobic polymer substance (JP-A-57-1929).
It is known to be isolated from other components by encapsulation with No. 44). However, in these encapsulation methods, wax or a polymer substance is dissolved in a solvent thereof, and a color-forming component is dissolved or dispersed in the solution to form a capsule, which is a shell around the core substance. Its function is different from that of the Otsuta capsule. Therefore, when the chromogenic composition is dissolved and formed, the chromogenic component does not become the core substance of the capsule but is uniformly mixed with the encapsulating substance, and the pre-coupling progresses sufficiently during storage at the capsule wall interface during storage. It is not possible to obtain good raw preservation. Further, in the case where the color-forming component is dispersed and formed, the color-forming reaction does not occur unless the wall of the capsule is melted by heat, so that the heat-coloring property is deteriorated. Further, there is a manufacturing problem in that the solvent used for dissolving the wax or the polymer substance must be removed after the capsule is formed, which is not satisfactory.

Therefore, in order to solve these problems, at least one of the components involved in the color development reaction is contained in a core substance, and a wall is formed around the core substance by polymerization to form microcapsules. It has been found that an excellent thermal recording material can be obtained.

"Problems to be Solved by the Invention" However, even in the heat-sensitive recording material prepared by this microencapsulation method, the thermochromic property is not yet sufficient, and the optical density of the image-recorded portion is increased due to long-term storage after heat recording. It may be apparently lowered, and further improvement has been desired.

"Object of the invention" Therefore, a first object of the present invention is to provide a heat-sensitive recording material which is excellent in thermal responsiveness and high in heat coloration.

A second object of the present invention is to provide a thermosensitive recording material in which the recorded image density is less likely to decrease due to long-term storage after thermal recording.

"Means for Solving Problems" As a result of earnest studies, the inventors of the present invention have shown that, in a heat-sensitive recording material in which a recording layer containing a diazo compound and a coupling component is coated on a support, the following general formula (I) is used. The object of the present invention has been achieved by a heat-sensitive recording material characterized by containing the compound shown in the recording layer. The general formula (I)
In the formula, X represents an oxygen atom or a sulfur atom, and R represents an alkyl group containing at least one of an ester group, a carbonyl group and an amide group as a substituent.

In the general formula (I), R preferably has a structure represented by the following general formula (II).

—R ₁ —Y ₁ —R ₂ (II) In the above general formula (II), Y ₁ represents any _one of an ester group, a carbonyl group and an amide group, and R ₁ represents a substituted or unsubstituted C 1-10 group. A divalent group containing a substituted alkylene group or cycloalkylene group and a substituted or unsubstituted arylene group having 6 to 12 carbon atoms, and a methylene group is particularly preferable. R ₂ represents a substituted or unsubstituted alkyl group or aryl group.

The compound represented by the general formula (I) in the present invention is preferably a compound having a melting point of 50 ° C to 250 ° C, particularly 65 ° C to 200 ° C. Furthermore, the solubility in water is 4 or less,
Particularly, 0.5 or less is preferable from the viewpoint of storage resistance of the recording material.

Further, in the present invention, it is preferable that either the diazo compound or the coupling component is contained in the microcapsules.

The microcapsule of the present invention is destroyed by heat or pressure to bring the reactive substance contained in the core of the microcapsule into contact with the reactive substance outside the microcapsule as used in conventional recording materials. The reaction does not cause a color development reaction, but the reaction occurs mainly through the walls of the microcapsule by heating the reactive substance existing outside and the core of the microcapsule.

As a result of intensive research on a heat-sensitive recording material using such microcapsules, the present inventors have excellent raw storage stability, improved thermochromic properties, and improved optical density of a recorded image by long-term storage after thermal recording. It has been found that it is extremely effective to include the compound represented by the general formula (I) in the layer in addition to the diazo component and the coupling component in order to eliminate the decrease.

Specific examples of the compound represented by formula (I) according to the present invention include the followings.

(1) Methyl 4-hydroxyphenoxyacetate (2) Ethyl 4-hydroxyphenoxyacetate (3) 4-n-butyl 4-hydroxyphenoxyacetate (4) Phenyl 4-hydroxyphenoxyacetate (5) Benzyl 4-hydroxyphenoxyacetate (6) Methyl 4-hydroxyphenoxypropionate (7) Acetic acid-4-hydroxyphenoxymethyl (8) Propionate-4-hydroxyphenoxymethyl (9) Benzoic acid -4-Hydroxyphenoxymethyl (10) 4-hydroxyphenoxyethyl acetate (11) Methyl 4-hydroxyphenylthioacetate (12) 4-Hydroxyphenylethyl thioacetate (13) 4-Hydroxyphenyl Benzyl thioacetate (14) α-4-Hydroxyphenoxyacetone (15) 4-Hydroxyphenoxymethylphenyl ketone (16) α-4-Hydroxyphenyl thioacetone (17) 4-hydroxy Cyphenyl thiomethyl phenyl ketone (18) N-methyl-4-hydroxyphenoxyacetic acid amide (19) N-benzyl-4-hydroxyphenoxyacetic acid amide and the like can be mentioned.

The diazo compound used in the present invention has a general formula of ArN ₂ ^{+ X −.}
(In the formula, Ar represents an aromatic moiety, N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion.) A diazonium salt represented by a coupling component and a coupling reaction to develop a color. It is a compound that can be decomposed by light.

As the aromatic moiety, specifically, those having the following general formula are preferred.

In the formula, Y represents a hydrogen atom, a substituted amino group, an alkoxy group, an aryloxy group, an arylthio group, an alkylthio group or an acylamino group, and R represents a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an arylamino group or Represents halogen (I, Br, Cl, F). n is 1
Or represents 2.

The substituted amino group of Y includes a monoalkylamino group, a dialkylamino group, an arylamino group, a morpholino group,
A piperidino group and a pyrrolidino group are preferred.

Specific examples of the diazonium forming a salt include 4-diazo-1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, 4-diazo-1-methylbenzylamino. Benzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methyl Benzene, 4-diazo-1-benzoylamino-
2,5-diethoxybenzene, 4-diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-
Diethoxybenzene, 4-diazo-1-morpholino-
2,5-dibutoxybenzene, 4-diazo-1-anilinobenzene, 4-diazo-1-toluylmercapto-
2,5-diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-diethoxybenzene, 4-diazo-1-pyrrolidino-2-ethylbenzene and the like can be mentioned.

Specific examples of the acid anion include CnF _{2n +} COO ⁻ (n is 3 to 9).
_{Integer), CmF 2m + 1 SO 3} - (m is 2-8 integer), (ClF
_{2l + 1 SO 2) 2 CH} - (l 1 to 18 _{integer), B (C 6 H 5} ) 4 -, Examples thereof include BF ₄ ⁻ and PF ₆ ⁻ .

In particular, as the acid anion, those containing a perfluoroalkyl group or a perfluoroalkenyl group, or PF ₆ ⁻ is preferable because it does not increase fog during storage.

Specific examples of the diazo compound (diazonium salt) include the following examples.

The coupling component used in the present invention is one that couples with a diazo compound (diazonium salt) in a basic atmosphere to form a dye, and specific examples include resorcin, phloroglucin and 2,3-dihydroxynaphthalene-6-sulfonic acid. Sodium, 1-hydroxy-2-
Naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene,
2,3-dihydroxy-6-sulfanylnaphthalene,
2-Hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-2'-methylanilide, 2
-Hydroxy-3-naphthoic acid ethanolamide, 2-
Hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyl-oxy-propylamide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide,
Benzoyl acetanilide, 1-phenyl-3-methyl-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl) -3-benzamido-5-pyrazolone, 1
Examples include-(2 ', 4', 6'-trichlorophenyl) -3-anilino-5-pyrazolone and 1-phenyl-3-phenylacetamido-5-pyrazolone. Further, by using two or more of these coupling components in combination, an image of any color tone can be obtained.

It is preferable to add a basic substance to the heat-sensitive recording material of the present invention in order to promote color development, but as the basic substance, a poorly water-soluble or water-insoluble basic substance or a substance which generates an alkali by heating is used. Used.

As the basic substance, inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. And nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines and pyridines. Specific examples thereof include ammonium acetate, tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allylurea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenyl. Imidazole, 2-
Phenyl-4-methyl-imidazole, 2-undecyl-imidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2-
Imidazoline, 2-phenyl-2-imidazoline, 1,
2,3-triphenylguanidine, 1,2-ditolylguanidine, 1,2-dicyclohexylguanidine, 1,
2,3-tricyclohexylguanidine, guanidine trichloroacetate, N, N'-dibenzylpiperazine,
There are 4,4'-dithiomorpholine, morpholinium trichloroacetate, 2-amino-benzothiazole, 2-benzoylhydrazino-benzothiazole. These basic substances can be used in combination of two or more.

In the present invention, the reactive substance contained in the core substance of the microcapsule is dissolved or dispersed in a water-insoluble organic solvent, and after emulsification, the microcapsule wall is formed by polymerization. Those having a boiling point of 180 ° C. or higher are preferable. Specifically, phosphoric acid ester, phthalic acid ester, other carboxylic acid ester, fatty acid amide, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane and the like are used. Specific examples include tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate,
Dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyl triethyl citrate, octyl maleate, dibutyl maleate, isopropyl Biphenyl, isoamylbiphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane, 2,
4-ditersialinaminophenol, N, N-dibutyl-2-butoxy-5-tersialyoctylaniline and the like can be mentioned.

Of these, ester solvents such as dibutyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are particularly preferable.

The microcapsules of the present invention are produced by emulsifying a core substance containing a reactive substance and then forming a wall of a polymer substance around the oil droplets. The reactant forming the polymer substance is added inside the oil droplet and / or outside the oil droplet. Specific examples of the polymer substance include polyurethane, polyurea,
Polyamide, polyester, polycarbonate, urea-
Formaldehyde resin, melamine resin, polystyrene,
Examples thereof include styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like.

Two or more polymer substances can be used in combination. Preferred polymeric substances are polyurethane, polyurea, polyamide,
Polyester and polycarbonate, more preferably polyurethane and polyurea.

As a method of producing the microcapsule wall of the present invention, the effect is particularly large when the microencapsulation method by polymerizing the reactant from the inside of the oil droplet is used. That is, it is possible to obtain capsules having a uniform particle size within a short period of time, which are preferable as a recording material having excellent raw storability.

This technique and specific examples of compounds are described in the specifications of US Pat. Nos. 3,726,804 and 3,796,669.

For example, when polyurethane is used as a capsule wall material, a polyisocyanate and a second substance (for example, a polyol) which reacts with the polyisocyanate to form a capsule wall are mixed in an oily liquid to be encapsulated, emulsified and dispersed in water, and then the temperature is increased. By rising, a polymer forming reaction is caused at the oil droplet interface to form a microcapsule wall. At this time, an auxiliary solvent having a low boiling point and a strong dissolving power can be used in the oily liquid.

In this case, regarding the polyisocyanate to be used and the polyol and polyamine to be reacted therewith, U.S. Pat. Nos. 3,281,383, 3,773,695, 3,793,268, and JP-B-48-40347 are used. 49-24159, JP-A-48-80191, and JP-A-48-80191.
No. 8-84086, and they can also be used.

Further, tin salt or the like can be used together to accelerate the urethanization reaction.

In particular, it is preferable to use polyisocyanate as the first wall film-forming substance and polyol as the second wall film-forming substance because of good raw storability. Also, by combining the two, the thermal permeability of the reactive substance can be arbitrarily changed.

Examples of the polyvalent isocyanate that is the first wall film forming substance include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and naphthalene-1,4. -Diisocyanate, diphenylmethane-
4,4'-diisocyanate, 3,3'-dimethoxy-
4,4'-biphenyl-diisocyanate, 3,3'-
Dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4 '
-Diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate,
Propylene-1,2-diisocyanate, butylene-
1,2-diisocyanate, cyclohexylene-1,2
-Diisocyanates, diisocyanates such as cyclohexylene-1,4-diisocyanate, 4,4 ', 4 "-
Triphenylmethane triisocyanate, toluene-
Triisocyanates such as 2,4,6-triisocyanate, 4,4'-dimethyldiphenylmethane-2,
Tetraisocyanate such as 2 ', 5,5'-tetraisocyanate, addition product of hexamethylene diisocyanate and trimethylolpropane, addition product of 2,4-tolylene diisocyanate and trimethylolpropane, addition of xylylene diisocyanate and trimethylolpropane And an isocyanate prepolymer such as an addition product of tolylene diisocyanate and hexanetriol.

Examples of the polyol that is the second wall film forming substance include aliphatic and aromatic polyhydric alcohols, hydroxypolyesters, and hydroxypolyalkylene ethers. Examples of preferable polyols include polyhydroxy compounds having a molecular weight of 5000 or less and having the following group (I), (II), (III) or (IV) in the molecular structure between two hydroxyl groups.

(I) Aliphatic hydrocarbon group having 2 to 8 carbon atoms (II) (III) (IV) Here, (II), (III) , Ar is a substituted or a (IV), represents an aromatic moiety of unsubstituted, and aliphatic hydrocarbon group (I), -CnH ₂ n- was a basic skeleton The hydrogen group may be replaced with another element.

Specific examples thereof include (I) ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3
-Dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,4-pentanediol, 2,5-
Hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,
Examples thereof include 6-trihydroxyhexane, phenylethylene glycol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, and glycerin.

Examples of (II) include condensation products of aromatic polyhydric alcohols such as 1,4-di (2-hydroxyethoxy) benzene and resorcinol dihydroxyethyl ether with alkylene oxides.

Examples of (III) include p-xylylene glycol, m
-Xylylene glycol, α, α'-dihydroxy-p
-Examples include diisopropylbenzene.

Examples of (IV) include 4,4'-dihydroxy-diphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl) benzyl alcohol, an adduct of ethylene oxide with bisphenol A, and a propylene oxide with bisphenol A. Things can be given. Polyol has a ratio of hydroxyl groups of 0.0 with respect to 1 mol of isocyanate groups.
It is preferably used in an amount of 2 to 2 mol.

When making the microcapsules, a water-soluble polymer can be used, and the water-soluble polymer may be any of a water-soluble anionic polymer, nonionic polymer and amphoteric polymer.
Examples of the anionic polymer, either natural can be used even be synthetic, for example -C00 ^-, include those having a -SO ₃ group, and the like. Specific anionic natural polymers include arabic gum and alginic acid, and semi-synthetic products include carboxymethyl cellulose, phthalated gelatin, sulfated starch, sulfated cellulose,
Lignin sulfonic acid etc.

Further, synthetic products include maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid-based) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, Examples include carboxy-modified polyvinyl alcohol.

Examples of the nonionic polymer include polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose and the like.

Examples of amphoteric compounds include gelatin.

These water-soluble polymers are used as 0.01-10 wt% aqueous solutions. The particle size of the microcapsules is adjusted to 20 μm or less. Generally, when the particle size exceeds 20 μ, the print image quality tends to deteriorate.

In particular, when heating with a thermal head is performed from the coating layer side, it is preferably 8 μm or less in order to avoid pressure fog.

The diazo compound which is the main component used in the present invention, the coupling component and the basic substance which is optionally used are used as any one of them as the core substance of the microcapsules, or two or three of them. Can be used. When two kinds are contained in the core substance of the microcapsules, the same microcapsules or separate microcapsules may be used. Further, when three kinds are contained in the core substance of the microcapsule, the same microcapsule cannot contain three kinds at the same time, but there are various combinations. Other components not contained in the core material of the microcapsules are used in the heat-sensitive layer outside the microcapsules.

The compound represented by the general formula (I) of the present invention may be the core or the outside of the microcapsule.

When making a microcapsule, it can be made from an emulsion containing 0.2 wt% or more of a component to be microencapsulated.

A diazo compound used in the present invention, a coupling component,
And, if the basic substance used as necessary is contained in the inside of the microcapsule or in the heat-sensitive layer outside the microcapsule, the coupling component is 0.1 to 10 parts by weight with respect to 1 part by weight of the diazo compound. It is preferable to use 0.1 part to 20 parts by weight of the basic substance. The diazo compound is preferably applied in an amount of 0.05 to 5.0 g / m ² .

When the diazo compound, the coupling component and the basic substance used in the present invention are not microencapsulated, it is preferable to use them by solid dispersion with a water-soluble polymer by a sand mill or the like. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules.
At this time, the concentration of the water-soluble polymer is 2 to 30 wt%,
The diazo compound, the coupling component, and the basic substance are added to the water-soluble polymer solution so as to be 5 to 40 wt% each.

The dispersed particle size is preferably 10 μm or less.

In the heat-sensitive recording material of the present invention, various compounds such as ethers, phenols, sulfonamides, carboxylic acid amides, esters, ketones, aryls and alkanols may be used in combination with the thiohydroquinone derivative for the purpose of further improving the thermochromic property.

For example, 2-benzyloxynaphthalene 1-p-biphenyloxy-2-phenylethane, 2-benzyloxynaphthalene, 2-
Benzoyloxynaphthalene 2-phenoxyacetyloxynaphthalene 2-p-chlorobenzyloxynaphthalene 1-hydroxy-2-phenoxycarbonylnaphthalene, 1,4-bisphenoxybutane 1,2-bis-m-tolyloxy Ethane 1-phenoxy-2-p-ethylphenoxyethane,
1,2-diphenoxyethane 1-phenoxy-2-p-chlorophenoxyethane, bis (phenoxyethyl) oxalate 1-phenoxy-2-p-methoxyphenoxyethane,
β-chloroethoxynaphthalene 1-phenoxy-2-p-tolyloxyethane, bis (phenoxyethyl) carbonate, biphenyl-β-
Methoxyethyl ether p-biphenyl-β-cyclohexyloxyethyl ether, β-cyanoethoxynaphthalene, β-chloroethoxy-p-biphenyl 2-phenoxyphenyloxycarbonylphenol,
2-p-biphenyloxycarbonylphenol, 2-
β-naphthyloxycarbonylphenol, bis (2-
p-methoxyphenoxyethyl) ether, bis (2-
p-Ethoxyphenoxyethyl) ether bis (2-p-methoxyphenoxyethoxy) methyl ether, 1,2-bis-4-methoxythiophenoxyethane, or other ether, or butylphenol, p-t -Octylphenol, p-
α-cumylphenol, pt-pentylphenol,
2,5-Dimethylphenol, 2,4,5-Trimethylphenol, 3-Methyl-4-isopropylphenol, p-Benzylphenol, o-Cyclohexylphenol, p- (Diphenylmethyl) phenol, p-
(Α, α-Diphenylethyl) phenol, o-phenylphenol, ethyl p-hydroxybenzoate, chloropyr p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-methoxyphenol, p- Butoxyphenol, p-heptyloxyphenol, p-benzyloxyphenol, 3
-Hydroxyphthalic acid, dimethyl vanillin 2,5-diethylphenol, 1,1-bis (4-hydroxyphenyl) dodecane, 1,1-bis (4-hydroxyphenyl) -2-ethyl-hexane, 1,1 -Bis (4-hydroxyphenyl) -2-methyl-pentane,
2,2-bis (4-hydroxyphenyl) -heptane,
Vanillin 2-t-butyl-4-methoxyphenol, 2,6-dimethoxyphenol, 2,2'-dihydroxy-4-methoxybenzophenone, β-resorcinic acid phenoxyethyl ester, orseric acid-α-methylbenzyl Ester, phenol such as methyl hydroxycinnamate, or ethylbenzenesulfonamide, toluenesulfonamide, methoxybenzenesulfonamide, ethyltoluenesulfonamide, chloroethoxybenzenesulfonamide, (iso) propylbenzenesulfonamide, ethoxytoluenesulfonamide, t -Sulfones such as amylbenzenesulfonamide, diethylbenzenesulfonamide, allylbenzenesulfonamide, ethoxybenzenesulfonamide and cyclohexylbenzenesulfonamide. Alternatively de acid, Benz amides, m- methoxy benz amide, methyl Benz amides, ethyl Benz amides, isopropyl Benz amides, butyl Benz amides,
t-amylbenzamide, cyclohexylbenzamide, dimethylbenzamide, nicotinamide, picolinamide, naphthamide, phenylbenzamide, chlorobenzamide, o-chlorobenzamide, methoxychlorobenzamide, methoxytoluamide, ethoxybenzamide, Butylbenzamide, dimethylnaphthamide,
Trimethylbenzamide, dimethylchlorobenzamide, dimethoxychlorobenzamide, dimethoxybenzamide, diethoxybenzamide, chlorophenoxyacetamide, pivaloylamide, 2-ethylhexanoic acid amide, p-acetoxybenzamide, diethylaminobenzamide, phthalamide, methoxy Carbonyl benzamide, methoxy naphthamide, benzyl benzamide, chloroethyl benzamide, chloroethoxy benzamide, cyano benzamide, benzyloxy benzamide and the like, more preferably o-toluamide, o
-Chlorobenzamide, p-ethylbenzamide, p-
Isopropylbenzamide, p-phenylbenzamide, α-toluamide, 2,4-dichlorobenzamide,
2,4-dimethylbenzamide, o, m or p-methoxybenzamide, o, m or p-ethoxybenzamide, 2,4-diethoxybenzamide, 4-ethoxy-
An amide compound such as 2-hydroxybenzamide, acetoxybenzamide, o, m or p-butoxybenzamide, or hydroxybenzoin, p-methylbenzoin, p,
p'-dimethylbenzoin, p-methoxybenzoin,
Xylylenediol, hydroxymethylbiphenyl, hydroxymethyltoluene, p-methoxybenzyl alcohol, β, β-bis-p-chlorophenylethanol,
p-hydroxybenzyl alcohol, 3-methoxy-4
-Hydroxybenzyl alcohol, 3-butoxy-4-
Hydroxybenzyl alcohol, 2,3-dihydroxypropoxybiphenyl, 1-phenoxy-3-p-hydroxyphenoxypropanol, 2-hydroxymethyl-4-phenylphenol, α, α-bishydroxyphenylmethylbenzyl alcohol , P-carbamoylbenzyl alcohol, p-sulfamoylbenzyl alcohol, 4-β-phenethylbenzyl alcohol and other arylalkanols.

These compounds can be used by forming microcapsules with the core substance of the microcapsules or by adding them to the coating liquid of the heat-sensitive recording material and existing outside the microcapsules. Is preferred. In any case, the amount used is 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, relative to 1 part by weight of the coupling component, but it may be appropriately selected in order to adjust the desired color density. Good.

To the heat-sensitive recording material of the present invention, a free radical generator (a compound capable of generating a free radical upon irradiation with light) used in a photopolymerizable composition or the like for the purpose of reducing yellowing of the background portion after light fixation is added. be able to. As the free radical generator, aromatic ketones (for example, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamine) benzophenone, 4-methoxy-4 ′ (dimethylamino) benzophenone, 4,4'-dimethoxybenzophenone, 4-dimethylaminobenzophenone, 4-
Methoxy-3,3'-dimethylbenzophenone, 1-hydroxycyclohexylphenyl ketone, 4-dimethylaminoacetophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1.
-Acetophenone-benzyl), cyclic aromatic ketones (eg, fluorenone, anthrone, xanthone, thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, acridone, N-ethylacridone, benz Anthrone), quinones (eg, benzoquinone 2,3,5-
Trimethyl-6-bromobenzoquinone, 2,6-di-n
-Decylbenzoquinone, 1,4-naphthoquinone, 2-isopropoxy-1,4-naphthoquinone, 1,2-naphthoquinone, anthraquinone, 2-chloro-anthraquinone, 2-methylanthraquinone, 2-tert-butylanthraquinone, phenanthra Quinone), benzoin,
Benzoin ethers (eg, benzoin methyl ether, benzoin ethyl ether, 2,2-dimethoxy-
2-phenylacetophenone, α-methyl benzoin methyl ether), aromatic polycyclic hydrocarbons (for example,
Naphthalene, anthracene, phenanthrene, pyrene), azo compounds (for example, azobisisobutyronitrile, α-azo-1-cyclohexanecarbonitrile, azobisvaleronitrile), organic disulfides (for example, thiuram disulfide), acyloxy Esters (eg, benzyl- (o-ethoxycarbonyl)-
α-monooxime).

The amount added is based on 1 part by weight of the diazonium compound.
The free radical generator is preferably 0.01 to 5 parts by weight. More preferably, it is in the range of 0.1 to 1 part by weight.

By encapsulating the free radical generator together with the diazonium salt as the core substance of the microcapsule, it is possible to reduce the yellow coloring of the background portion after the above-mentioned photofixation.

In the heat-sensitive recording material of the present invention, a polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as a vinyl monomer) can be used for the purpose of reducing yellow coloring of the background portion after light fixation. A vinyl monomer is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and is a monomer, a prepolymer, that is, a dimer, a tripler or another oligomer. It has a chemical form such as a mixture thereof or a copolymer thereof. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids with aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids with aliphatic polyhydric amine compounds.

Vinyl monomer is 0.2 with respect to 1 part by weight of diazo compound.
Used in a proportion of up to 20 parts by weight. The proportion is preferably 1 to 10 parts by weight.

The vinyl monomer is used by containing it in the core material of the microcapsule together with the diazo compound. At this time, part or all of the organic solvent used as the solvent (or dispersion medium) of the core material can be replaced with the vinyl monomer. It need not be added to harden the material.

When the thermosensitive recording material of the present invention contains a diazo compound as a core substance, the coupling reaction deactivator is contained in addition to the microcapsules so that the diazo compound existing in the aqueous phase and the diazo compound in the incomplete capsule are contained. The compound (that is, the diazo compound that is not completely blocked by the capsule wall) reacts with the coupling reaction deactivator, and the diazo compound undergoes the coupling reaction (coloring reaction).
You can lose the ability and prevent fogging.

The coupling reaction deactivator may be any substance that reduces the coloration of the solution in which the diazo compound is dissolved, and the diazo compound may be dissolved in water or an organic solvent and then dissolved in water or an organic solvent. It can be selected by adding the compound and observing the color change of the diazo compound.

Specific examples thereof include hydroquinone, sodium bisulfite, potassium nitrite, hypophosphorous acid, stannous chloride and formalin. Besides this, K. H. Sawn ders "The Aromatic Diazo-Compo
unds and Their Technical
Applications "M. C. , M .; A (Can
t ab. ) B. Sc. (London), published in 1949, pages 105 to 306.

The coupling reaction quenching agent is preferably one in which the quenching agent itself is less colored and has less side effects. More preferably, it is a water-soluble substance.

The coupling reaction deactivator is used to the extent that it does not hinder the thermal color development of the diazo compound, but the deactivator is usually used in the range of 0.01 to 2 mol per mol of the diazo compound. It is more preferably used in the range of 0.02 mol to 1 mol.

The coupling reaction quencher of the present invention is prepared by dissolving microcapsules containing a diazo compound after being dissolved in a solvent,
Alternatively, it is used by adding it to a liquid in which a coupling agent or a basic substance is dispersed, or a mixed liquid thereof. Preferably, the quenching agent is used as an aqueous solution.

The heat-sensitive recording material of the present invention contains silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide, for the purpose of preventing sticking to the thermal head and improving the writability.
Pigments such as calcium carbonate and fine powders such as styrene beads and urea-melamine resin can be used.

Similarly, metal soaps can be used to prevent staking. The amount of these used is 0.
It is ² to 7 g / cm ² .

Further, in the heat-sensitive recording material of the present invention, a heat-melting substance can be used to increase the heat-recording density. The heat-melting substance is a substance that is solid at room temperature and has a melting point of 50 to 150 ° C. that melts when heated by a thermal head, and is a substance that dissolves a diazo compound, a coupling component or a basic substance. The heat-fusible substance is dispersed in the form of particles of 0.1 to 10 μ, and is used in an amount of solid content of 0.2 to 7 g / m ² . Specific examples of the heat-fusible substance include fatty acid amide, N-substituted fatty acid amide, Kent compound, urea compound and ester.

The heat-sensitive recording material of the present invention can be coated with a suitable binder.

As the binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, arabic rubber, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic ester, ethylene-vinyl acetate copolymer Various emulsions of polymers can be used. The amount used is a solid content of 0.5 to 5 g / m ² .

In the present invention, in addition to the above materials, citric acid as an acid stabilizer,
Tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid can be added.

The heat-sensitive recording material of the present invention is a coating solution containing a diazo compound, a main component of a coupling component, a basic substance and other additives, and is bar-coated or blade-coated on a support such as paper or a synthetic resin film. The solid content is 2.5 to 2 by coating and drying by a coating method such as air knife coating, gravure coating, roll coating coating, spray coating, and dip coating.
A thermosensitive layer of 5 g / m ² is provided. As another method, the main component of the coupling component and the basic substance and other additives are added as the core substance of the microcapsules, or they are dispersed as a solid, or they are dissolved as an aqueous solution and mixed to prepare a coating liquid, A precoat layer having a solid content of ² to 10 g / m ² is provided on the support by coating and drying, and the diazo compound as the main component and other additives are further added as the core substance of the microcapsule on the precoat layer, or It is also possible to form a laminated type in which a coating solution prepared by dispersing a solid or dissolving as an aqueous solution and then mixing is applied and dried to provide a coating layer having a solid content of 1 to 15 g / m ² . The lamination type thermal recording material may be formed by laminating the layers in the reverse order, and the coating method may be sequential coating or simultaneous coating of the layers. This laminated-type heat-sensitive recording material is particularly excellent in long-term storability.

It is also possible to apply a heat-sensitive layer after providing an intermediate layer described in Japanese Patent Application No. 177669/1984 on the support.

As the paper used for the support, heat extraction pH 6 sized by neutral size such as alkyl ketene dimer is used.
~ 9 neutral paper (as described in JP-A-55-14281)
Is advantageous in terms of storage stability over time.

Further, in order to prevent the penetration of the coating liquid into the paper and to improve the contact between the recording heat head and the heat-sensitive recording layer, JP-A-57-116 is used.
687, Moreover, paper having a smoothness of 90 seconds or more is advantageous.

Paper having an optical surface roughness of 8 .mu.m or less and a thickness of 40 to 75 .mu.m described in JP-A-58-136492,
Paper having a density of 0.9 g / cm ³ or less and an optical contact ratio of 15% or more, described in JP-A No. 8-69091, JP-A-58-690.
Canadian standard water degree described in No. 97 (JIS P812
Paper is made from beating pulp of 400cc or more in 1),
Paper that prevents the coating liquid from soaking in, and JP-A-58-6569.
No. 5, which improves the color density and resolution by using the glossy surface of the base paper produced by the Yankee machine as the coating surface, and the coating suitability of corona discharge treatment on the base paper described in JP-A-59-35985. Papers and the like with improved properties are also used in the present invention and give good results. In addition to these, any of the supports generally used in the field of heat-sensitive recording paper can be used as the support of the present invention.

The heat-sensitive recording material of the present invention can be used as printer paper for facsimiles and electronic calculators that require high-speed recording, and can be fixed by exposing after exposure to heat and decomposing unreacted diazo compounds. . In addition to this, it can also be used as a thermal phenomenon type copying paper.

"Examples of the Invention" Examples will be shown below, but the present invention is not limited thereto. In addition, "part" indicating the addition amount represents "part by weight".

Example 1 3.45 parts of the following diazo compound and a (3: 1) adduct 1 of trimethylolpropane with xylylene diisocyanate 1
8 parts was added to a mixed solvent of 24 parts tricresyl phosphate and 5 parts ethyl acetate and dissolved. The solution of this diazo compound was mixed with an aqueous solution in which 5.2 parts of polyvinyl alcohol was dissolved in 58 parts of water, and the mixture was emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 2.5 μ. 100 parts of water is added to the obtained emulsion.
Parts were added, and the mixture was heated to 60 ° C. with stirring, and after 2 hours, a capsule liquid containing a diazo compound in the core substance was obtained.

(Diazo compound) Next, 10 parts of 2-hydroxy-3-naphthoic acid anilide and 10 parts of triphenylguanidine were added to 100 parts of a 5% aqueous solution of polyvinyl alcohol and dispersed in a sand mill for about 24 hours to obtain an average particle size of 3 μ coupling component and triphenylguanidine. A dispersion was obtained.

Further, add 4 parts of methyl 4-hydroxyphenoxyacetate 20 parts.
Add 100 parts of polyvinyl alcohol aqueous solution and 100 parts of water and disperse with a paint shaker for 2 hours to obtain an average particle diameter of 3 μm.
Dispersion A was obtained.

Capsule liquid 5 of diazo compound obtained as described above
A coupling component, 24 parts of a dispersion of triphenylguanidine, and 28 parts of a dispersion A were added to 0 part to prepare a coating solution.
This coating solution was applied onto smooth wood free paper (50 g / m ² ) using a coating bar so that the dry weight was 10 g / m ² , and dried at 25 ° C. for 30 minutes to obtain a heat-sensitive material.

Examples 2 to 7 In the same manner as in Example 1 except that the compound represented by the general formula (I) of the present invention shown in Table 1 was used in place of the methyl 4-hydroxyphenoxyacetate of Example 1. A thermosensitive recording material was obtained.

Comparative Examples 1 to 2 Thermal recording materials were obtained in the same manner as in Example 1 except that the sensitivity improvers shown in Table 1 were used instead of the 4-hydroxyphenoxymethyl acetate of Example 1.

(Test Method) The obtained thermal recording material was thermally recorded using a GIII mode thermal printer (Hyfax 700; manufactured by Hitachi Ltd.), and then Ricopy Super Dry 100.
The entire surface was exposed using (Ricoh Co., Ltd.) and fixed.
The blue density of the obtained recorded image was measured by a Macbeth reflection densitometer. In addition, the yellow density of the background part was also measured.

The results are shown in Table 1. On the other hand, when heat recording was performed again on the fixed portion, it was confirmed that no image was recorded on any of the fixed portions.

Next, in order to examine the decrease in the optical density of the color-developed portion due to long-term storage after thermal recording, the recorded image of the thermal recording material was
It was stored in the dark for 16 hours under the condition of ° C, and the degree of decrease in the density of the recorded image after the forced deterioration test was evaluated.

The results are shown in Table 1.

From these results, it can be seen that the effect of the compound of the present invention is remarkable in improving the image density and effective in preserving recorded images.

Claims (1)

[Claims] 1. A heat-sensitive recording material in which a recording layer containing a diazo compound and a coupling component is coated on a support, wherein the compound represented by the following general formula (I) is contained in the recording layer. Thermosensitive recording material. In the above general formula, X represents an oxygen atom or a sulfur atom,
R represents an alkyl group containing at least one of an ester group, a carbonyl group and an amide group.