JPH0643146B2 - Thermal recording material - Google Patents

Description

The present invention relates to a heat-sensitive recording material, and more particularly to a diazo heat-sensitive recording material which can be fixed. More specifically, the present invention relates to a heat-sensitive recording material which is excellent in preservability before heat recording, has a high color density during heat recording, and is capable of optical fixing after heat recording.

"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 precoupling by allowing any one of the coloring components to exist in the form of particles in a discontinuous state. (Hereinafter, referred to as raw storability) is not yet sufficient, and there is a drawback that the thermochromic property is deteriorated.
As another measure, it is known to separate the diazo compound and the coupling component as separate layers in order to minimize contact between the components (for example, the above-mentioned JP-A-57-123).
086). 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 nonpolar wax-like substance (JP-A-57-44141 and JP-A-57-14263).
No. 6) and hydrophobic macromolecular substances (JP-A-57-19294).
It is known to be isolated from other components by encapsulating (No. 4). However, these encapsulation methods are ones in which 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, and a shell is surrounded around the core substance. Its function is different from that of the Otsuta capsule. Therefore, when the color-forming component is formed by dissolving, the color-forming component is not mixed with the capsule and the core substance but uniformly mixed with the encapsulating substance, and the pre-coupling progresses sufficiently during storage at the capsule wall interface during storage. Raw preservation cannot be obtained. 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 by this microencapsulation method, the thermal response at the time of high-speed recording cannot be said to be sufficient, and the long-term storage after the thermal recording causes the image The optical density of the recorded portion may be apparently lowered, and further improvement has been desired.

"Object of the invention" Therefore, a first object of the present invention is a heat-sensitive material which has excellent raw storability, quick thermal response, high thermochromic property, and little decrease in recorded image density due to long-term storage after thermal recording. To provide recording material.

A second object of the present invention is to provide a heat-sensitive recording material capable of photolyzing and fixing unreacted diazo compound after thermal recording.

A third object of the present invention is to provide a heat-sensitive recording material having excellent manufacturability.

“Means for Solving Problems” As a result of earnest research by the present inventors, in a heat-sensitive recording material having a recording layer containing a diazo compound and a coupling component on a support, either the diazo compound or the coupling component was used. One is contained in microcapsules,
The above object was achieved by using a heat-sensitive recording material characterized in that the recording layer contains a phenol derivative whose ortho position is substituted with a hydroxymethyl group.

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. In order to eliminate the decrease, it is extremely effective to include, in addition to the diazo component and the coupling component, a phenol derivative in which at least one of the two ortho positions is substituted with a hydroxymethyl group in the layer. I found it.

Preferred examples of the phenol derivative in the present invention include compounds represented by the following general formula (I).

In the above formula, R ₁ , R ₂ and R ₃ are a hydrogen atom, an alkyl group,
Aryl group, alkoxy group, aryloxy group, arylalkyloxy group, alkylthio group, arylthio group, acylthio group, halogen atom, carbamoyl group, sulfamoyl group, hydroxyalkyl group, substituted amino group, cyano group, nitro group, acyl group, Represents an acyloxy group or a sulfo group. Any _{two of} R ₁ , R ₂ and R ₃ may combine with each other to form a ring.

Of these, compounds having a melting point of 50 ° C to 250 ° C, particularly 65 ° C to 200 ° C are preferred for the present invention. Further, a compound having a solubility in water of 4 or less, particularly 0.5 or less is preferable from the viewpoint of resistance of the recording material obtained.

Of the phenol derivatives represented by the above general formula (I), those represented by the following general formulas (II) and (III) are particularly preferable.

In the above formula, X represents an oxygen atom or a sulfur atom, and R ₄
Represents an alkyl group or an aryl group which may have a substituent, and the substituent of R ₅ , R ₆ and R ₄ is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, an amino group or a substituted amino group. Group, cyano group, nitro group,
Acyl group, acyloxy group, sulfo group, carbamoyl group, sulfamoyl group, alkylthio group, aryl group,
It represents an arylthio group or an acylthio group.

Further, as the phenol derivative of the present invention, a derivative in which both ortho positions of the phenolic hydroxyl group are substituted with hydroxymethyl groups also gives preferable results.

Examples of specific compounds are as follows.

2-hydroxymethyl-4-methylphenol, 2-hydroxymethyl-4-ethylphenol, 2-hydroxymethyl-4-phenylphenol, 2-hydroxymethyl-4-benzylphenol, 2-hydroxymethyl-4-methoxyphenol , 2-hydroxymethyl-4
-Phenoxyphenol, 2-hydroxymethyl-4-
Benzyloxyphenol, 2-hydroxymethyl-4
-Methoxycarbonylphenol, 2-hydroxymethyl-4-phenoxycarbonylphenol, 2-hydroxymethyl-4-benzyloxycarbonylphenol, 2-hydroxymethyl-4-acetylphenol,
2-hydroxymethyl-4-benzoylphenol, 2
-Hydroxymethyl-4-benzylcarbonylphenol, 2-hydroxymethyl-4-phenylthiophenol, 2-hydroxymethyl-4-benzylthiophenol, 2-hydroxymethyl-4-N-benzylaminophenol, 2-hydroxymethyl -4- (2-phenoxyethylthio) phenol, 2-hydroxymethyl-4
-(2-phenylthioethylthio) phenol, 2-hydroxymethyl-4-chlorophenol, 2-hydroxymethyl-4-bromophenol, 2,6-bis (hydroxymethyl) -4-methylphenol, 2,6 -Bis (hydroxymethyl) -4-ethylphenol, 2,6-bis (hydroxymethyl) -4-
Phenylphenol, 2,6-bis (hydroxymethyl) -4-benzylphenol, 2,6-bis (hydroxymethyl) -4-methoxyphenol, 2,6-bis (hydroxymethyl) -4-phenoxyphenol ,
2,6-bis (hydroxymethyl) -4-benzyloxyphenol, 2,6-bis (hydroxymethyl) -4
-Methoxycarbonylphenol, 2,6-bis (hydroxymethyl) -4-phenoxycarbonylphenol, 2,6-bis (hydroxymethyl) -4-benzyloxycarbonylphenol, 2,6-bis (hydroxymethyl)- 4-acetylphenol, 2,6-bis (hydroxymethyl) -4-benzoylphenol,
2,6-bis (hydroxymethyl) -4-benzoylcarbonylphenol, 2,6-bis (hydroxymethyl) -4-benzylthiophenol, 2,6-bis (hydroxymethyl) -4-N-benzylaminophenol, 2,6-bis (hydroxymethyl) -4- (2-phenoxyethylthio) phenol, 2,6-bis (hydroxymethyl) -4- (2-phenylthioethylthio)
Phenol, 2,6-bis (hydroxymethyl) -4-
Chlorophenol, 2,6-bis (hydroxymethyl)
-4-Bromophenol 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 the formula, which undergoes a coupling reaction with a coupling component 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 , 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-dibenzinluminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2- Methylbenzene, 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 C _n F _{2n + 1} COO ⁻ (n is 3 to
9 _{integer), C m F 2m + 1} SO 3 - (m is 2-8 integer), (C _l F
_{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 the increase of fog during storage is small.

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, benzoylacetanilide, 1- Phenyl-3-methyl-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl) -3-benzamido-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl) ) −
3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamido-5-pyrazolone and the like can be mentioned.
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, stearinamine, 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 decomposed by a water-insoluble organic solvent, and after emulsification, the microcapsule wall is formed by polymerization around the organic solvent. It is preferable that it has a boiling point of 180 ° C. or higher. Specifically, phosphate ester,
Phthalates, other carboxylic esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylethanes 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 trimitrate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamylbiphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane,
2,4-diter-sialinaminophenol, N, N-dibutyl-2-butoxy-5-tersiaoctylaniline 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, uric acid-
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 the compounds are described in the specifications of US Pat. Nos. 3,726,804 and 3,796,669.

For example, when polyurethane is used as the 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 wall of the microcapsule. 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, and 3,793 are used.
No. 268, Japanese Patent Publication No. 48-40347, and No. 49-241.
59, JP-A-48-80191 and 48-8408.
No. 6, which can 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, adduct of hexamethylene diisocyanate and trimethylolpropane, adduct 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, Ar in (II), (III) and (IV) represents a substituted or unsubstituted aromatic moiety, and the aliphatic hydrocarbon group in (I) means -CnH _2n -as 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'-dihydroxyphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl) benzyl alcohol, an adduct of ethylene oxide with bisphenol A, and propylene oxide with bisphenol A. And the like. The proportion of hydroxyl groups in polyol is 0.02 per mol of isocyanate group.
It is preferred to use ~ 2 moles.

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.
As the anionic polymer, a natural one or a synthetic one can be used, and examples thereof include those having a —COO ⁻ , —SO ₃ ^— group and the like. Specific examples of anionic natural polymers include arabic gum and alginic acid, and semi-synthetic products include carboxymethyl cellulose, phthalated gelatin, sulfated starch, sulfated cellulose, ligninsulfonic acid and the like.

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 grain 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 of microcapsules are contained in the core material of the microcapsules, they may be the same microcapsules or different microcapsules. Further, when three kinds are contained in the core material of the microcapsule, the same microcapsule cannot contain three kinds at the same time, but there are various combinations. The other part not contained in the core material of the microcapsule is used for the heat-sensitive layer outside the microcapsule.

The arylalkanol compound of the present invention may be placed on the core or 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 and ketones may be used in combination with the phenol derivative of the present invention for the purpose of further improving the thermochromic property.

2-benzyloxyquinaphthalene, 1-p-biphenyloxy-2-phenylethane, 2-benzoyloxynaphthalene, 2-phenoxyacetyloxynaphthalene, 2
-P-chlorobenzyloxynaphthalene, 1-hydroxy-2-phenoxycarbonylnaphthalene, 1,4-bisphenoxybutane, 1,2-bis-m-tolyloxyethane, 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
Ether such as -bis-4-methoxyphenoxyethane, or butylphenol, pt-octylphenol, p-α-cumylphenol, pt-pentylphenol, 2,5-dimethylphenol, 2,4,4 5-trimethylphenol, 3-methyl-4-isopropylphenol, p-benzylphenol, o-cyclohexylphenol, p- (diphenylmethyl) phenol,
p- (α, α-diphenylethyl) phenol, o-phenylphenol, ethyl p-hydroxybenzoate, p
-Chloropyl hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-methoxyphenol, p-butoxyphenol, p-heptyloxyphenol, p-benzinyloxyphenol, 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 hydroxycinnamic acid or ethylbenzenesulfonamide, toluenesulfonamide, methoxybenzenesulfonamide, ethyltoluene Sulfonamide, chloroethoxybenzenesulfonamide, (iso) propylbenzenesulfonamide,
Sulfonamides such as ethoxytoluenesulfonamide, t-amylbenzenesulfonamide, diethylbenzenesulfonamide, allylbenzenesulfonamide, ethoxybenzenesulfonamide and cyclohexylbenzenesulfonamide, or benzamide, m-methoxybenzamide, methylbenzamide, Ethylbenzamide, isopropylbenzamide, butylbenzamide, t-amylbenzamide, cyclohexylbenzamide, dimethylbenzamide, nicotinamide, picolinamide, naphthamide, phenylbenzamide, chlorobenzamide, o-chlorobenzamide, methoxy Chlorobenzamide, methoxytoluamide, ethoxybenzamide, butylbenzamide, dimethylnaphthamide, trimethylbenzamide Amide, dimethylchlorobenzamide, dimethoxychlorobenzamide, dimethoxybenzamide, diethoxybenzamide, chlorophenoxyacetamide, pivaloylamide, 2-ethylhexanoic acid amide, p-acetoxybenzamide, diethylaminobenzamide, phthalamide, methoxycarbonylbenz Amide, methoxynaphthamide, benzylbenzamide, chloroethylbenzamide, chloroethoxybenzamide, cyanobenzamide, benzyloxybenzamide 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-2-hydroxybenzamide, acetoxybenzamide, o, m
Alternatively, an amide compound such as p-butoxybenzamide can be used.

These compounds can be used either by forming a microcapsule together with the core substance of the microcapsule or by adding it to the coating liquid of the heat-sensitive recording material and existing outside the microcapsule. Is preferred. In any case, the amount used is 0.01 to 10 parts by weight, preferably 0.1 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 to a desired color density. Good.

To the heat-sensitive recording material of the present invention, a free radical generator (a compound that generates a free radical upon irradiation with light) used in a photopolymerizable composition or the like for the purpose of reducing yellow coloring of the background portion after light fixation is added. You can As the free radical generator, aromatic ketones (for example, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) 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, phenanthraquinone), benzoin,
Benzoin ethers (eg, benzoin methyl ether, benzoin ethyl ether, 2,2-dimethoxy-
2-phenylacetophenone, α-methylolbenzoin 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, prepolymer, that is, dimer, trimer or other The oligomer has a chemical form such as a mixture thereof and 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 cyazo compound that is not completely blocked by the capsule wall) reacts with the coupling reaction quencher, and the diazo compound reacts with 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 medium. It is possible to make a selection by adding the above 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-Compounds and Their Technical Appli
cations ”MC, MA (Cant ab.) B. Sc. (London) 194
You can also choose from the ones listed on pages 105 to 306, issued 9 years.

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 such an extent that it does not interfere with the thermal coloring reaction of the diazo compound, but it is usually the diazo compound 1
The deactivator is used in the range of 0.01 to 2 mol per mol. It is more preferably used in the range of 0.02 mol to 1 mol.

The coupling reaction quencher of the present invention is a liquid in which microcapsules containing a diazo compound are dispersed 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 / m 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 μm and used in an amount of 0.2 to 7 g / m ² of solid content.
Specific examples of the heat-fusible substance include fatty acid amide, N-substituted fatty acid amide, ketone compound, urea compound, ester and the like.

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 0.5 to 5 g / m ² of solid content.

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 comprises a diazo compound, a coupling component, a main component of a coating solution containing a basic substance and other additives, and a bar is coated on a support such as paper or a synthetic resin film, Solid content of 2.5 after coating and drying by a coating method such as blade coating, air knife coating, gravure coating, roll coating coating, spray coating, and dip coating.
A heat sensitive layer of ˜25 g / m ² is provided. As another method, the coupling component, the main component of the basic substance and other additives are added as the core substance of the microcapsule,
Alternatively, it may be dispersed in a solid state or dissolved in an aqueous solution and then mixed to prepare a coating solution, which is coated on a support and dried to provide a precoat layer having a solid content of ² to 10 g / m ² , and the main component is further formed thereon. A diazo compound and other additives are added as a core substance of microcapsules, or they are dispersed in a solid state or dissolved in an aqueous solution and mixed to prepare a coating solution, which is then dried to obtain a solid content of 1 to 15 g / m 2. ^Two
It is also possible to use a laminated type in which a coating layer is provided. 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.

The paper used for the support is heat extracted pH 6 sized with a neutral sizing agent such as alkyl ketene dimer.
~ 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.

Further, papers having an optical surface roughness of 8 μm or less and a thickness of 40 to 75 μm described in JP-A-58-136492,
-69091, paper having a density of 0.9 g / cm ³ or less and an optical contact ratio of 15% or more, JP-A-58-69097.
Paper made from pulp that has been beaten to 400 CC or more according to Canadian Standard Freeness (JIS P8121) described in Japanese Patent No. 58-65695, and made by a Yankee machine described in JP-A-58-65695. Also used in the present invention are those which use the glossy surface of the coated base paper as a coating surface to improve the color density and resolution, and which are described in JP-A-59-35983, in which the coating suitability is improved by subjecting the base paper to corona discharge treatment. The
Gives 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 heat-developing copying paper.

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

"Examples of the invention" Example 1 3.45 parts of the following diazo compound and (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 was emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle diameter of 2.5 μ. Water 10 is added to the obtained emulsion.
0 part was 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 a coupling component having an average particle size of 3 μm and triphenylguanidine. I got a fraction of

Further, 20 parts of 2-hydroxymethyl-4-benzylthiophenol was added to 100 parts of a 4% polyvinyl alcohol aqueous solution,
100 parts of water was added and dispersed with a paint shaker for 2 hours to obtain a dispersion liquid having an average particle diameter of 3 μm.

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 of 2-hydroxymethyl-4-benzylthiophenol were added to 0 parts to prepare a coating solution. This coating solution was applied to 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 and 3 Instead of 2-hydroxymethyl-4-benzylthiophenol of Example 1, 2,6-bis (hydroxymethyl)-
4-benzylthiophene, 2-hydroxymethyl-
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 4-methylphenol was used.

Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1, except that 4-benzyloxyphenol was used instead of 2-hydroxymethyl-4-benzylthiophenol 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.

In addition, in order to investigate the raw storability under high temperature and high humidity conditions,
60 ° C, 30% RH, 24 hours (dry thermo) and 40 ° C, 90% RH, 24 hours (wet thermo)
The background color development (background fogging) was measured under the following two conditions.

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.

As a result, in all of Examples 1 to 3, image density> 1.2, background yellow density <0.08, decrease in recorded image density after forced deterioration test <5%, dry thermo coloring <
0.15 and wet thermo coloration <0.15, showing excellent characteristics as compared with the one using 4-benzyloxyphenol of Comparative Example 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, excellent in raw storage stability, and effective in storage stability of recorded images.

Claims (1)

[Claims] 1. A heat-sensitive recording material having a recording layer containing a diazo compound and a coupling component on a support,
One of the diazo compound and the coupling component is contained in a microcapsule, and the recording layer contains a phenol derivative in which the ortho position is substituted with a hydroxymethyl group.