JPH0655546B2 - 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 pre-coupling by allowing any one of the coloring components to exist in the form of discontinuous particles (solid dispersion). The storage stability (hereinafter referred to as raw storage stability) is not sufficient and 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 the contact between the components (see, for example, the above-mentioned Japanese Patent Laid-Open No. Sho 5).
7-123086). 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 raw storability and 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-57-1).
No. 42636) and hydrophobic macromolecular substances (JP-A-57-1).
It is known to be separated from other components by encapsulation with No. 92944). 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. It is different from the general concept of capsules.
Therefore, when the color-forming component is formed by dissolution, the color-forming component does not become the core substance of the capsule but is uniformly mixed with the encapsulating substance, and the pre-coupling gradually progresses during storage at the capsule wall interface. Raw shelf life is not fully satisfied. 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 the core substance, and a wall is formed around the core substance by polymerization to form microcapsules. An excellent heat-sensitive recording material was found in Japanese Patent Application No. 58-65043).

"Problems to be Solved by the Invention" However, even in the case of the heat-sensitive recording material prepared by the microencapsulation method, the optical density of the image-recorded portion may be apparently lowered due to long-term storage after the heat-recording. Was 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 raw storability, has a high thermochromic property, and has a small decrease in recorded image density due to long-term storage after thermal recording. Especially.

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" An object of the present invention is to provide a arylsulfonamide represented by the following general formula (I) in a heat-sensitive recording material in which a recording layer containing a diazo compound and a coupling component is coated on a support. This has been achieved by a heat-sensitive recording material characterized in that at least one compound is contained in the recording layer.

In the above formula, R represents an alkyl group having 2 to 12 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. Incidentally, it is preferable that either one of the diazo compound and 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 a sulfonamide compound in the layer in addition to the diazo component and the coupling component in order to eliminate the decrease.

Preferable examples of the arylsulfonamide compound in the present invention include p-ethylbenzenesulfonamide, p-methoxybenzenesulfonamide, p-ethoxybenzenesulfonamide and p-isopropylbenzenesulfonamide.

The diazo compound used in the present invention has the general formula ArN ₂ ⁺ X
^- (wherein, Ar represents an aromatic moiety, N ₂ ⁺ represents a diazonium group, X ^-. Is representative of the acid anion) a diazonium salt represented by the color development undergoes a coupling component and a coupling reaction 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).

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-etherbenzene and the like can be mentioned.

Specific examples of the acid anion include CnF _{2n + 1} COO ⁻ (n
Is an integer of 3 to 9), CmF _{2m + 1} SO ₃ ⁻ (m is an integer of 2 to 8), ClF _{2l + 1} SO ₂ ) ₂ CH ⁻ (l is an integer of 1 to 18), 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 raw 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 monofolinopropylamide, 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, 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, dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate. , Dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, 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. As it rises, a polymer forming reaction occurs 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, 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, 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, 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.

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 of (I) include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, and 1,7. -Heptanedinol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3
-Dihydroxybutane, 2,2-dimethyl-2,3-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 propylene oxide with bisphenol A. Examples include adjuncts. The polyol has a ratio of hydroxyl groups of 0.1 mol to 1 mol of isocyanate groups.
It is preferably used in an amount of 02 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.
The anionic polymer can be used even as be of natural or synthetic, for example -COO ^{-, -S} ▲ O - ₃
▼ Those having a group and the like can be mentioned. Specific anionic natural polymers include arabic gum and alginic acid, and semi-synthetic products include carboxymethyl cellulose and
Examples include phthalated gelatin, sulfated starch, sulfated cellulose and lignin sulfonic acid.

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 arylsulfonamide compound of the present invention may be applied to the core of the microcapsule or to the outside thereof.

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.

A hydroxy compound, a carbamic acid ester compound, an aromatic methoxy compound or an organic sulfonamide compound can be added to the heat-sensitive recording material of the present invention for the purpose of improving the thermochromic property. It is considered that these compounds lower the melting point of the coupling component or the basic substance or improve the heat permeability of the microcapsule wall, resulting in a higher practical concentration.

Specific examples of the hydroxy compound include pt-butylphenol, pt-octylphenol, p-α-cumylphenol, pt-pentylphenol, m-xylenol, 2,5-dimethylphenol, 2, 4,5-
Trimethylphenol, 3-methyl-4-isopropylphenol, p-benzylphenol, o-cyclo-hexylphenol, 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, dimethyl vanillin 3-hydroxyphthalate,
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
-Phenol compounds such as -methoxyphenol, 2,6-dimethoxyphenol, 2,2'-dihydroxy-4-methoxybenzophenone, 2,5-dimethyl-2,
5-hexanediol, resorcinol di (2-hydroxyethyl) ether, resorcinol mono (2-hydroxyethyl) ether, salicyl alcohol, 1,4
-Di (hydroxyethoxy) benzene, p-xylylenediol, 1-phenyl-1,2-ethanediol, diphenylmethanol, 1,1-diphenylethanol,
2-methyl-2-phenyl-1,3-propanediol, 2,6-dihydroxymethyl-p-cresol benzyl ether, 2,6-dihydroxymethyl-p-cresol benzyl ether, 3- (o-methoxyphenoxy) ) -1,2-Propanediol, and other alcohol compounds. Specific examples of the carbamic acid ester compound include N-phenylcarbamic acid ethyl ester,
Examples thereof include N-phenylcarbamic acid benzyl ester, N-phenylcarbamic acid phenethyl ester, carbamic acid benzyl ester, carbamic acid butyl ester, and carbamic acid isopropyl ester. Specific examples of the aromatic methoxy compound include 2-methoxybenzoic acid, 3,5-dimethoxyphenylacetic acid, 2-methoxynaphthalene, 1,3,5-trimethoxybenzene, p-dimethoxybenzene, p-benzyloxymethoxy. Examples thereof include benzene.

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 capable of generating free radicals upon irradiation with light) used in a photopolymerizable composition or the like for the purpose of reducing the background and yellow coloring after photofixing is added. be able to. 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'-methoxybenzophenone, 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 (for example, fluorenone, anthrone, xanthone, thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone,
Acridone, N-ethylacridone, benzoanthrone), 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-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 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-Comounds and Their Technical
Applications "M. C. , M .; A. (Cant ab.)
B. Sc. (London) Issued 1949, pages 105-30
You can also select from the ones listed on page 6.

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 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, 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 a solid content of 0.5 to ⁵ g to 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 comprises a diazo compound, a coupling component, a main component of a coating solution containing a basic substance and other additives, bar coating on a support such as paper or a synthetic resin film, and a blade. Solid content of 2.5 to 2.5 after coating and drying by coating methods such as 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 main component of the coupling component, the basic substance and other additives are added as the core substance of the microcapsules, or they are dispersed in the solid form, or they are dissolved as an aqueous solution and mixed to prepare a coating liquid. Or by coating on a support and drying to form a precoat layer having a solid content of ² to 10 g / m ² , and further adding a diazo compound as the main component and other additives as a core substance of the microcapsule thereon, Alternatively, 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.

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.

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-58-6909.
Canadian standard water degree described in No. 7 (JIS P8121)
Paper made from pulp that has been beaten to 400 CC or more in order to prevent the penetration of the coating liquid, the glossy surface of the base paper made by the Yankee machine, as described in JP-A-58-65695, is used as the coating surface, and the color density and Papers having improved resolving power, such as those described in JP-A-59-35985, in which base paper is subjected to corona storage treatment to improve coating suitability, 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 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 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 the 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. A dispersion of

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

Capsule liquid 5 of diazo compound obtained as described above
A coupling solution, 24 parts of a dispersion of triphenylguanidine, and 28 parts of a dispersion of p-ethylbenzenesulfonamide were added to 0 part to prepare a coating solution. This coating solution was applied to a smooth high-quality 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.

Example 2 Except that p-methoxybenzenesulfonamide was used in place of p-ethylbenzenesulfonamide of Example 1,
A heat-sensitive recording material was obtained in the same manner as in Example 1.

Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that p- (2-chloroethoxy) benzenesulfonamide was used in place of p-ethylbenzenesulfonamide of Example 1.

Example 4 Except that p-octylbenzenesulfonamide was used in place of p-ethylbenzenesulfonamide of Example 1,
A heat-sensitive recording material was obtained in the same manner as in Example 1.

Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that p-toluenesulfonamide was used instead of p-ethylbenzenesulfonamide in Example 1.

(Test method) The obtained thermal recording material was subjected to thermal recording using a GIII mode thermal printer (Hyfax 700; manufactured by Hitachi, Ltd.), and then the entire surface was recorded using Ricopy Super Dry 100 (manufactured by Ricoh Co., Ltd.). It was exposed 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 check the raw storability, the background density (fog) of the thermosensitive recording material was measured, and the thermosensitive recording material was further tested at 40 ° C. and a relative humidity of 9
It was stored in a dark place for 24 hours under the condition of 0% RH, and the fog after the forced deterioration test was measured with a Macbeth reflection densitometer,
I saw the change in fog.

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.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a recording layer containing a diazo compound and a coupling component coated thereon, wherein at least one arylsulfonamide compound represented by the following general formula (I) is contained in the recording layer. A heat-sensitive recording material comprising: In the above formula, R represents an alkyl group having 2 to 12 carbon atoms or an alkoxy group having 1 to 5 carbon atoms.