JPH0444595B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a heat-sensitive recording material, and particularly to a fixable diazo-based heat-sensitive recording material. More specifically, it relates to a heat-sensitive recording material that has a white background tone, excellent storage stability before thermal recording, high color density during thermal recording, and light fixation after thermal recording. "Prior Art" A leuco coloring type heat-sensitive recording material is usually used as a recording material used in a heat-sensitive recording method. However, this heat-sensitive recording material has the disadvantage that color develops in unexpected places due to harsh handling, heating, or adhesion of solvents after recording, which stains the recorded image. In recent years, research has been actively conducted on diazo color-forming heat-sensitive recording materials as heat-sensitive recording materials that do not have these drawbacks. For example, JP-A-57-123086
No., Journal of the Institute of Image Electronics Engineers, 11, 290 (1982), etc., it is disclosed in After recording, light irradiation is performed to decompose unreacted diazo compounds and stop color development. Indeed, according to this method, it is possible to stop color development (hereinafter referred to as fixing) in areas that do not require recording. However, this recording material also undergoes gradual pre-coupling during storage, and undesirable coloring (fogging) may occur.
To this end, it has been attempted to prevent contact between the components and prevent pre-coupling by making one of the coloring components exist in the form of discontinuous particles (solid dispersion). It has the disadvantage that its storage stability (hereinafter referred to as raw storage stability) is not yet sufficient and that its thermochromic properties are reduced. 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 Japanese Patent Laid-Open No.
123086). Although this method improves raw storage stability, the thermal coloring properties are greatly reduced, and it cannot respond to high-speed recording with short pulse widths, making it impractical. Furthermore, as a method to satisfy both raw storage stability and heat color development, either the coupling component or the basic substance is replaced with a non-polar wax-like substance (Japanese Patent Application Laid-Open No.
It is known to isolate it from other components by encapsulating it with a hydrophobic polymer substance (Japanese Patent Application Laid-Open No. 57-192944). However, these encapsulation methods involve dissolving wax or polymeric substances in their solvents, and dissolving or dispersing coloring components in these solutions to form capsules. It is different from the concept of a normal capsule covered with For this purpose, if the coloring component is dissolved and formed, the coloring component will not become the core material of the capsule, but will mix uniformly with the encapsulating material, and pre-coupling will gradually progress during storage at the wall interface of the capsule. Raw storage stability is not fully satisfied. In addition, when a color-forming component is dispersed and formed, the color-forming reaction does not occur unless the capsule wall is thermally melted, resulting in a decrease in thermal color-forming properties. Furthermore, there is a manufacturing problem in that the solvent used to dissolve the wax or polymer substance must be removed after the capsules are formed, and this method is not completely satisfactory. Therefore, in order to solve these problems, there is a method in which at least one component involved in color reaction is contained in a core material, and a wall is formed around this core material by polymerization to form a microcapsule. Hope
58-65043), an excellent heat-sensitive recording material was discovered. ``Problems to be Solved by the Invention'' However, even with heat-sensitive recording materials made using this microencapsulation method, when photofixed after thermal recording, the background portion (parts other than the recorded image)
However, the drawback of a slight yellowish tinge was unavoidable. ``Object of the Invention'' Therefore, the first object of the present invention is to provide a heat-sensitive recording material that has a white background tone, has excellent storage stability, and has high thermochromic properties. A second object of the present invention is to provide a heat-sensitive recording material that can be fixed by photodecomposing unreacted diazo compounds after heat recording. A third object of the present invention is to provide a heat-sensitive recording material with excellent manufacturing suitability. "Means for Solving the Problems" As a result of intensive research, the present inventors have found that a recording layer containing a diazo compound, a coupling component, and a basic substance or a substance that becomes basic by heat is formed on a support. A heat-sensitive recording material provided with the diazo compound and a polymerizable compound having an ethylenically unsaturated bond are both contained in microcapsules,
In addition, the walls of the microcapsules are covered with a heat-sensitive recording material made of a polymer material formed around the core material by polymerization after emulsifying the core material of the microcapsules. The heat-sensitive recording material of the present invention can stop the coloring property of the diazo compound by photodecomposing the unreacted diazo compound after it is thermally colored. It is also possible to first imagewise expose and then uniformly heat the unexposed portions to thermally color them. "Operation" The microcapsules of the present invention can be destroyed by heat or pressure, as used in conventional recording materials, to separate the reactive substances contained in the core of the microcapsules and the reactive substances outside the microcapsules. This method does not cause a coloring reaction by contacting the microcapsules with each other, but by heating the reactive substance present in the core and outside of the microcapsules, the reaction mainly occurs through the microcapsule walls. This reaction is called a coupling reaction, and although a colored image is obtained by this reaction, the diazo compound that is not used in the reaction is decomposed by light and converted into a compound that is incapable of coupling reaction. At this time, the diazo compound generally takes on a yellowish tinge due to photolysis, but if a polymerizable compound is present as in the present invention, the diazo compound will not take on a yellowish tinge due to photolysis, and the coupling reaction ability will also be improved. It gets lost. This mechanism is not clear, but since the effect does not occur when the polymerizable compound polymerizes, a polymerization initiator is not necessarily required, and it does not need to be included to the extent that it will harden through polymerization. The effect is seen. The present invention will be described in further detail. In the present invention, the polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as a vinyl monomer) is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure. and has chemical forms such as monomers, prepolymers, dimers, trimers and other oligomers, mixtures thereof, and copolymers thereof. Examples thereof include unsaturated carboxylic acids and their salts, esters with aliphatic polyhydric alcohol compounds, amides with aliphatic polyhydric amine compounds, and the like. Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid. Salts of unsaturated carboxylic acids include sodium and potassium salts of the aforementioned acids. Specific examples of esters of aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids include acrylic esters such as ethylene glycol diacrylate, triethylene glycol triacrylate,
1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, 1,4-cycloxanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol Diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, sorbitol triacrylate, sorbitol tetraacrylate,
Examples include sorbitol pentaacrylate, sorbitol hexaacrylate, and polyester acrylate oligomers. Examples of methacrylic esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate,
Trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol dimethacrylate, sorbitol trimethacrylate,
Sorbitol tetramethacrylate, bis-[p
-(3-methacryloxy-2-hydroxypropoxy)phenyl]dimethylmethane, bis-[p
-(acryloxyethoxy)phenyl]dimethylmethane, etc. Examples of itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, and pentaerythritol diitaconate. , sorbitol tetrataconate, etc. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaeryloritol dicrotonate, and sorbitol tetracrotonate. Isocrotonic acid esters include ethylene glycol diisocrotonate, puntaerythritol diisocrotonate, sorbitol tetraisocrotonate, and the like. Examples of maleic esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, mixtures of the aforementioned esters may also be mentioned. Specific examples of amides of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide,
1,6-hexamethylenebis-acrylamide,
Examples include 1,6-hexamethylenebis-methacrylamide, diethylenetriamine trisacrylamide, xylylenebisacrylamide, xylylenebismethacrylamide, and the like. Other examples include polyisocyanate compounds having two or more isocyanate groups in one molecule described in Japanese Patent Publication No. 48-41708,
Examples include vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule to which a vinyl monomer containing a hydroxyl group represented by the following general formula is added. CH ₂ =C(R)COOCH ₂ CH(R')OH (where R and R' represent H or _CH3 . Preferred vinyl monomers used in the present invention include monofunctional or polyfunctional methacrylates and polyfunctional The vinyl monomer is used in an amount of 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, per 1 part by weight of the diazo compound.The vinyl monomer is used as the core material of the microcapsules together with the diazo compound. The diazo compound used in the present invention has the general formula ArN ₂ ⁺ X ^- (In the formula, Ar represents an aromatic moiety, and N ₂ ⁺
represents a diazonium group, and X ^- represents an acid anion. ) is a diazonium salt that can develop a color by causing a coupling reaction with a coupling component, and is a compound that can be decomposed by light. Specifically, as the aromatic moiety, those having the following general formula are preferable. In the formula, Y represents a substituted amino group, alkoxy group, arylthio group, alkylthio group, or acylamino group, and R represents an alkyl group, alkoxy group, arylamino group, or halogen (I, Br, Cl, F)
represents. The substituted amino group of Y includes a monoalkylamino group, a dialkylamino group, an arylamino group,
A morpholino group, a piperidino group, a pyrrolidino group, etc. are preferred. Specific examples of diazonium that form salts include:
4-Diazo-1-dimethylaminobenzene, 4-
Diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylamino benzene,
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-tolylmercapto-2,5-diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-diethoxybenzene, 4-diazo-1-pyrrolidino-2-ethylbenzene, etc. It will be done. A specific example of an acid anion is C _o F _2o+1 COO ^-
(n is an integer from 3 to 9), C _n F _2n+1 SO ₃ ^- (m is from 2 to
(C _l F _2l+1 SO ₂ ) ₂ CH ^- (l is an integer from 1 to 18), (n is an integer from 3 to 9) (n is an integer of 3 to 9) BF ₄ ^- , PF ₆ ^- and the like. In particular, as the acid anion, one containing a perfluoroalkyl group or a perfluoroalkenyl group, or PF ₆ ^- is preferable because there is little increase in 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 a diazo compound (diazonium salt) in a basic atmosphere.
It couples with the pigment to form the pigment,
Specific examples include resorcinol, phloroglucin,
Sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfonate Phanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-2'-methylanilide, 2-hydroxy-3-naphthoic acid anilide
-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, acetylamide Acetanilide, 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-phenylacetamide-
Examples include 5-pyrazolone and the like. Furthermore, by using two or more of these coupling components in combination, an image of any tone can be obtained. As the basic substance of the present invention, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali upon heating is used. Basic substances include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, and triazoles. Examples include nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines, and pyridines. Specific examples of these are:
For example, ammonium acetate, tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allyl urea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenylimidazole, 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, 4,4'-dithiomorpholine, morpholinium trichloroacetate,
These include 2-amino-benzothiazole and 2-benzoylhydrazino-benzothiazole. Two or more of these basic substances can also be used in combination. In the present invention, the diazo compound and vinyl monomer contained in the core material of the microcapsule are dissolved or dispersed in a water-insoluble organic solvent, and after emulsification, a microcapsule wall is formed around it by polymerization. The organic solvent preferably has a boiling point of 180°C or higher. Specifically, phosphate ester,
Phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane, etc. 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, and dioctyl sebacate. , dibutyl sebacate, dioctyl adipate, trioctyl trimellistate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane, 2, 4
- ditertiaryaminophenol, N,N-dibutyl-2-butoxy-5-tertiaryoctylaniline, and the like. Among these, ester solvents such as dibutyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are particularly preferred. Note that the organic solvent is used as a core material for emulsified droplets (consisting of diazo compounds, organic solvents, capsule-forming substances, etc.)
It is preferable to contain it in an amount of 10 to 70% by weight. More preferably, it is 20 to 55% by weight. The microcapsules of the present invention are made by emulsifying a core material containing a diazo compound and a vinyl monomer, and then forming a wall of a polymeric material around the oil droplets. A reactant forming a polymeric substance is added to the interior of the oil droplet and/or to the exterior of the oil droplet.
Specific examples of polymeric substances include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, etc. can be mentioned. Two or more types of polymeric substances can also be used in combination.
Preferred polymeric materials are polyurethane, polyurea, polyamide, polyester, polycarbonate, more preferably polyurethane and polyurea. The microcapsule wall of the present invention is particularly effective when using a microencapsulation method by polymerizing a reactant from inside an oil droplet. Achieves uniform particle size quickly and within a short time.
Capsules suitable as recording materials with excellent shelf life can be obtained. This method and specific examples of compounds are described in the specifications of US Pat. No. 3,726,804 and US Pat. No. 3,796,669. For example, when polyurethane is used as a capsule wall material, a polyvalent isocyanate and a second substance (such as a polyol) that reacts with it to form the capsule wall are mixed into the oily liquid to be encapsulated, emulsified and dispersed in water, and then heated to a temperature. Rather than rising,
A polymer formation reaction occurs at the oil droplet interface to form the microcapsule wall. At this time, a co-solvent with a low boiling point and strong dissolving power can be used in the oily liquid. In this case, regarding the polyisocyanate to be used and the polyol and polyamine that react with it, US Pat.
No. 3793268, Special Publication No. 48-40347, No. 49-24159,
It is disclosed in JP-A-48-80191 and JP-A-48-84086, and they can also be used. Furthermore, a tin salt or the like can also be used in combination to promote the urethanization reaction. Note that polyvalent isocyanate can also react with water to form a polymer film. In particular, it is preferable to use a polyvalent isocyanate as the first wall-forming substance and a polyol as the second wall-forming substance because of their good shelf life. Furthermore, by combining the two, it is also possible to arbitrarily change the thermal permeability of the reactive substance. 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, 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'-
Diisocyanates such as diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4′,4″-triphenylmethane triisocyanate, toluene-2,4,6-
Triisocyanates such as triisocyanate, 4,4'-dimethyldiphenylmethane-2,
Tetraisocyanates such as 2',5,5'-tetraisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, 2,4
- Isocyanate prepolymers such as adducts of tolylene diisocyanate and trimethylolpropane, adducts of xylylene diisocyanate and trimethylolpropane, and adducts of tolylene diisocyanate and hexanetriol. Examples of the polyol that is the second wall-forming substance include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, and hydroxy polyalkylene ethers. Preferred polyols include the following (), (),
Examples include polyhydroxy compounds having a molecular weight of 5,000 or less and having () or () groups in their molecular structure. () C2-8 aliphatic hydrocarbon group Here, Ar in (), (), and () represents a substituted or unsubstituted aromatic moiety, and the aliphatic hydrocarbon group in () has a basic skeleton of -C _o H _2o -,
Hydrogen groups may be substituted with other elements. To give a concrete example, as an example of (),
Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-
heptandinol, 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, 1,2,6-trihydroxyhexane, phenylethylene glycol, 1,
Examples include 1,1-trimethylolpropane, hexanetriol, pentaerythritol, and glycerin. Examples of () include condensation products of aromatic polyhydric alcohols and alkylene oxides such as 1,4-di(2-hydroxyethoxy)benzene and resorcinol dihydroxyethyl ether. Examples of () include p-xylylene glycol, m-xylylene glycol, α,α'-dihydroxy-p-diisopropylbenzene, and the like. An example of () is 4,4'-dihydroxy-
Examples include diphenylmethane, 2-(p,p'-dihydroxydiphenylmethyl)benzyl alcohol, an adduct of ethylene oxide to bisphenol A, and an adduct of propylene oxide to bisphenol A. It is preferable to use polyol in a ratio of 0.02 to 2 moles of hydroxyl groups per mole of isocyanate groups. When making microcapsules, water-soluble polymers can be used, and the water-soluble polymers may be any of water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. As the anionic polymer, both natural and synthetic polymers can be used, and examples thereof include those having -COO ^- , -SO ₃ ^- groups, and the like. Specific anionic natural polymers include gum arabic and alginic acid.
Carboxymethyl cellulose is a semi-synthetic product,
Examples include phthalated gelatin, sulfated starch, sulfated cellulose, and lignin sulfonic acid. Synthetic products include maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, Examples include carboxy-modified polyvinyl alcohol. Examples of nonionic polymers include polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose. Examples of amphoteric compounds include gelatin. These water-soluble polymers are used as a 0.01 to 10 wt% aqueous solution. The particle size of microcapsules is
Adjusted to 20μ or less. Generally, if the particle size exceeds 20μ, the print quality tends to be poor. In particular, when heating is performed from the coated layer side using a thermal head, the thickness is preferably 8 μm or less to avoid pressure fog. The diazo compound, which is the main component used in the present invention, the coupling component, and the diazo compound among the basic substances are used as the core material of the microcapsule, but the other two types may be contained in the core material of the microcapsule. It may exist outside the microcapsule. When the diazo compound and one other species are contained in microcapsules, they may be in the same microcapsule or in separate microcapsules. When the other two types are contained in a microcapsule, it is not possible to simultaneously contain the three types in the same microcapsule, but there are various combinations. Other ingredients not contained in the core material of the microcapsules are used in the heat-sensitive layer outside the microcapsules. When making microcapsules, diazo compounds are used
It can be made from an emulsion containing 0.2wt% or more. Whether the coupling component or basic substance used in the present invention is contained inside the microcapsule or in the heat-sensitive layer outside the microcapsule, the coupling component is 0.1 to 1 part by weight of the diazo compound. 10 parts by weight, basic substance is
It is preferable to use it in a proportion of 0.1 to 20 parts by weight. Moreover, it is preferable to apply the diazo compound at 0.05 to 5.0 g/m ² . When the coupling component and basic substance used in the present invention are not microencapsulated, they are preferably used after being dispersed in solid form with a water-soluble polymer using 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%, and the coupling component and the basic substance are each added to the water-soluble polymer solution at a concentration of 5 to 40 wt%. The dispersed particle size is preferably 10μ or less. The heat-sensitive recording material of the present invention contains the following ingredients for the purpose of preventing staking on a thermal head and improving writing properties.
Pigments such as silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide, and calcium carbonate, and fine powders such as styrene beads and urea-melamine resin can be used. Similarly, metal soaps can also be used to prevent statesking. The amount of these used is 0.2 to 7 g/m ² . Furthermore, a heat-melting substance can be used in the heat-sensitive recording material of the present invention in order to increase the heat-recording density. As a heat-melting substance, it is solid at room temperature and melts when heated with a thermal head, with a melting point of 50 to 150℃.
It is a substance that dissolves diazo compounds, coupling components, or basic substances. Heat-melting substances are dispersed into particles of 0.1 to 10 μm to reduce the solid content.
It is used in amounts of 0.2-7 g/m ² . Specific examples of heat-melting substances include fatty acid amides, N-substituted fatty acid amides, ketone compounds, urea compounds, esters, and the like. The heat-sensitive recording material of the present invention can be coated with a suitable binder. As a binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose,
Hydroxypropyl cellulose, gum arabic,
Various emulsions such as gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic ester, and ethylene-vinyl acetate copolymer 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, tartaric acid, oxalic acid, boric acid, phosphoric acid, and pyrophosphoric acid can be added as acid stabilizers. The heat-sensitive recording material of the present invention is produced by preparing a coating liquid containing a diazo compound, a coupling component, a basic substance as a main component, and other additives, and coating it on a support such as paper or a synthetic resin film by bar coating or blade coating. , applied by air knife coating, gelavia coating, roll coating coating, spray coating, dip coating, etc. and dried to a solid content of 2.5 to 25 g/m ²
A heat-sensitive layer is provided. Another method is to prepare a coating liquid by adding the coupling component, the main component of the basic substance, and other additives as the core material of the microcapsules, or by solid dispersing them, or by dissolving them as an aqueous solution and then mixing them. A precoat layer with a solid content of 2 to 10 g/m ² is formed by coating and drying on a support, and on top of that a coating solution containing a diazo compound as the main component and other additives as the core material of the microcapsules is applied. Coating, drying, solid content 1
It is also possible to use a laminated type with a coating layer of ~15 g/m ² . The laminated type heat-sensitive recording material may have a reverse order of lamination, and the coating method may be sequential coating or simultaneous coating of the laminated layers. This laminated type heat-sensitive recording material exhibits particularly excellent long-term storage stability. As the paper used for the support, heat-extracted neutral paper with a pH of 6 to 9 (described in JP-A-55-14281) sized with a neutral sizing agent such as an alkyl ketene dimer (described in JP-A No. 55-14281) can be used to improve storage stability over time. It is advantageous. In addition, in order to prevent the coating liquid from penetrating the paper and to improve the contact between the recording heat head and the heat-sensitive recording layer, the Steckigt sizing degree/(meter basis weight) described in JP-A-57-116687 is used. ² ≧3
×10 ^-3 and paper with a Beck smoothness of 90 seconds or more is advantageous. Also, paper with an optical surface roughness of 8μ or less and a thickness of 40 to 75μ described in JP-A-58-136492, JP-A-58-136492,
- Paper with a density of 0.9 g/cm ³ or less and an optical contact ratio of 15% or less as described in No. 69091, with a Canadian standard water level (JIS P8121) of 400 c.c. or more as described in JP-A-58-69097. A paper made from beaten pulp to prevent coating liquid from seeping in. The glossy side of base paper made by a Yankee machine is used as the coating surface to improve color density and resolution, as described in Japanese Patent Application Laid-Open No. 58-65695. Also, the paper described in Japanese Patent Application No. 57-145872, in which the base paper is subjected to a corona discharge treatment to improve its coating suitability, can also be used in the present invention and give good results. In addition to these, any support commonly 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 computers that require high-speed recording, and can be fixed by exposing it to light after heating and decomposing unreacted diazo compounds. . In addition, it can also be used as a heat-developable copying paper. Examples are shown below, but the present invention is not limited thereto. Note that "parts" indicating the amount added represent "parts by weight.""Example" Example 1 4 parts of the following diazo compound and xylylene diisocyanate and trimethylolpropane (3:1)
18 parts of the adduct were added to and dissolved in a mixed solvent of 6 parts of tricresyl phosphate, 18 parts of trimethylolpropane trimethacrylate, and 6 parts of dichloromethane. This diazo compound solution was mixed with polyvinyl alcohol.
5.2 parts are added to an aqueous solution in which 58 parts of water are dissolved,
Emulsification and dispersion was carried out at 20°C to obtain an emulsion with an average particle size of 2.5μ. 100 parts of water was added to the obtained emulsion and heated to 60° C. with stirring, and after 2 hours, a capsule liquid containing the diazo compound in the core material was obtained. (diazo compound) Next, 2-hydroxy-3-naphthoic acid anilide
10 parts of triphenylguanidine were added to 100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours to obtain a dispersion of the coupling component and triphenylguanidine with an average particle size of 3 μm. A coating solution was prepared by adding 24 parts of a dispersion of a coupling component and triphenylguanidine to 50 parts of the diazo compound capsule solution obtained as described above. This coating solution was coated on smooth high-quality paper (50 g/m ² ) using a coating rod to give a dry weight of 6 g/m ² and dried at 40° C. for 30 minutes to obtain a heat-sensitive recording material. The obtained heat-sensitive recording material was thermally recorded using G mode (Hi-Fax 700; manufactured by Hitachi, Ltd.), and then recorded using Ricopy Super Dry 100 (Ricoh Corporation).
The entire surface was exposed to light and fixed using a commercially available commercially available commercially available commercially available product. The blue density of the obtained recorded image was measured using a Macbeth reflection densitometer. Similarly, the yellow density of the background was measured. The results are shown in Table 1. On the other hand, when thermal recording was performed again on the fixed portions, no image was recorded on any of them, and it was confirmed that they were fixed. Next, in order to examine the shelf life of the heat-sensitive recording material, we examined the background density (fog) of the heat-sensitive recording material and
After storing in a dark place for 24 hours at ℃ and relative humidity of 90% RH, fog was measured using a Macbeth reflection densitometer after performing a forced deterioration test, and changes in fog were observed. The results are shown in Table 1. Examples 2 to 6 Heat-sensitive recording materials 2 to 6 were prepared in the same manner as in Example 1, except that the vinyl monomer shown in the table below was used instead of trimethylolpropane trimethacrylate in Example 1. It was tested in the same way. The results are shown in Table 1.

[Table] Example 7 In Example 1, 16 parts of the dispersion of p-benzyloxyphenol shown below was further added to the capsule liquid, and the resulting coating liquid was applied at a dry weight of 8 g/m ² A heat-sensitive recording material was obtained in the same manner as in Example 1. The recording material obtained was tested in the same manner as in Example 1, and the results are shown in Table 1. (Dispersion of p-benzyloxyphenol) 20 parts of p-benzyloxyphenol was added to 100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours to prepare a dispersion with an average particle size of 3 μm. Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethylolpropane trimethacrylate was omitted and 24 parts of tricresyl phosphate was used instead. The test results are shown in Table 1. Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethylolpropane trimethacrylate and tricresyl phosphate were removed and 24 parts of dibutyl phthalate was used instead. The test results are shown in Table 1.

【table】

[Table] "Effects of the Invention" As is clear from Table 1, the yellow density of the background part of Comparative Examples 1 and 2 is quite high, but the yellow density of Examples 1 to 7 of the present invention is low and has been improved. .

Claims (1)

[Claims] 1. A heat-sensitive recording material in which a recording layer containing a diazo compound, a coupling component, and a basic substance or a substance that becomes basic by heat is provided on a support, which contains the diazo compound and an ethylenically unsaturated bond. Both polymerizable compounds are contained in microcapsules, and the walls of the microcapsules are made of a polymer material formed by polymerization around the core material after emulsifying the core material of the microcapsule. Features of heat-sensitive recording material.