JPH0568356B2 - - 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 compound-based heat-sensitive recording material. <<Prior Art>> As a recording material used in a heat-sensitive recording method, a leuco color-forming heat-sensitive recording material is usually used. However, this heat-sensitive recording material has 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. These are, for example,
As disclosed in No. 57-123086, Journal of the Institute of Image Electronics Engineers, 11290 (1982), etc., recording materials using diazo compounds, coupling components, and basic components (including substances that become basic when heated) record heat,
Light irradiation is then performed to decompose the unreacted diazo compound and stop color development. It is true that this method can stop color development in areas that do not require recording (hereinafter referred to as fixing), but this recording material also gradually undergoes pre-coupling during storage, resulting in 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). The problem was that the storage stability (hereinafter referred to as raw storage stability) was still insufficient, and the thermal coloring property was reduced. On the other hand, in order to minimize contact between the components, it is known to separate the diazo compound and the coupling component as separate layers (for example, in the above-mentioned Japanese Patent Laid-Open No.
57-123086). Although this method improves raw storage stability, there is a significant decrease in thermal color development.
It is not practical because it cannot respond to high-speed recording with a short pulse width. Furthermore, as a method to satisfy both raw storage stability and thermochromic properties, 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
Capsules are formed by dissolving wax or polymeric substances in their solvents, and dissolving or dispersing color-forming ingredients in these solutions, and are different from ordinary capsules in which a core substance is surrounded by a shell. This is different from the concept, and when a capsule is formed by dissolving a coloring component, the coloring component does not become the core material of the capsule and is uniformly mixed with the encapsulating material. For this reason, pre-coupling gradually progresses at the wall interface of the capsule during storage, making the raw storage property unsatisfactory. In addition, when a color-forming component is dispersed and formed, the color-forming reaction does not occur unless the walls of the capsule are 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, so that they are not fully satisfactory as heat-sensitive recording materials. In order to solve these problems, at least one of the components involved in the color reaction is contained in a core material, and a wall is formed around this core material by polymerization to form a microcapsule. 59-190886) was disclosed. <<Problems to be Solved by the Invention>> However, even in the heat-sensitive recording material using the above-mentioned microencapsulation, when thermally recorded and then light-fixed, the background part (parts other than the recorded image) has a slight yellowish tinge. It was impossible to avoid the disadvantage of having Therefore, the first objective of the present invention is to provide a heat-sensitive recording material which 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>> The above-mentioned objects of the present invention are to provide a heat-sensitive recording material in which a recording layer containing at least a diazo compound and a coupling component is provided on a support, in which the diazo compound is added to the light amount. This was achieved by a heat-sensitive recording material that does not contain an initiator and is contained in microcapsules together with a polymerizable compound having an ethylenically unsaturated bond. After the heat-sensitive recording material of the present invention is thermally colored, it can be uniformly irradiated with light to stop the thermal coloring property of the uncolored diazo compound. Further, by uniformly heating after imagewise exposure, the diazo compound in the unexposed area can be thermally colored. The diazo compound used in the heat-sensitive recording material of the present invention is a diazonium salt represented by the general formula ArN ₂ +X ^- , and can develop a color by causing a coupling reaction with a coupling component, and can be decomposed by light irradiation. This is the compound obtained. (In the formula, Ar represents a substituted or unsubstituted aromatic moiety, N ₂ + represents a diazonium group, and X ⁻ represents an acid anion.) The aromatic moiety is represented by the following general formula.

embedded image In the formula, Y represents a substituted amino acid, an alkoxy group, an arylthio group, an alkylthio group, or an acylamino group, and R represents an alkyl group, an alkoxy group, an arylamino group, or a halogen (I, Br, Cl, F). Preferred examples of the substituted amino group for Y include a monoalkylamino group, dialkylamino group, arylamino group, monophorino group, piperidino group, and pyrrolidino group. 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, and the like. Specific examples of acid anions include CnF ₂ n+
1COO ^- (n is an integer from 3 to 9), CmF ₂ m + 1SO ₃ ^-
(m is an integer from 2 to 8), (ClF ₂ l+1SO ₂ )2CH ^- (l
is an integer from 1 to 18),

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[Chemical] Examples include BF ₄ ^- and PF ₆ ^- . In particular, as the acid anion, one containing a perfluoroalkyl group or a perfluoroalkenyl group, or PF ₆ ^- is preferable because of less increase in fog during raw storage. Specific examples of the diazo compound (diazonium salt) include the following examples.

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[Chemical] The coupling component used in the present invention includes one that promotes the formation of a pigment by coupling with a diazo compound (diazonium salt) in a basic atmosphere, and a basic substance as a coloring aid. There are some that can cause coupling even if they are not present. Specific examples of coupling components in which a basic substance is preferably present include resorcinol, phloroglycin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,
3-dihydroxy-6-sulfanylnaphthalene, 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-
Examples include hydroxy-3-naphthoic acid tetradecylamide. Examples of the coupling component which does not require the presence of a basic substance include compounds having active methylene in the molecule, aromatic amine compounds, and aromatic hydroxy compounds having a basic group in the molecule. Examples of active methylene compounds include β-ketocarboxylic acid amides [e.g., benzoylacetanilide, pivaloylacetanilide, 1,3-bis(benzoylacetamino)toluene, 1,3-
bis(pivaloylacetaminomethyl)benzene, etc.], pyrazolones [e.g., 3-hexylcarbamoyl-1-phenylpyrazolone, 3-myristoylamino-1-(2,4,6-trichlorophenyl)pyrazolone, etc.], Barbiturates [e.g. 1,3-didodecylbarbituric acid, 1,3-
dicyclohexylbarbituric acid, 1-octyl-3-stearylbarbituric acid, etc.], 1,3-
Examples include cyclohexanediones [for example, 5,5-dimethyl-1,3-cyclohexanedione, 5,5-dimethyl-4-phenyl-1,3-diclohexanedione, etc.]. Examples of aromatic amine compounds include α-naphthylamine, β-naphthylamine, 1-anilino-naphthalene, 2-anilino-naphthalene, 3-amino-diphenylamine, 4,4'-diaminodiphenylmethane, N,N-dicyclohexylaniline. , 2-aminocarbazole, 2-phenylindole, 1-phenyl-2-methylindole and organic acids of aromatic amines such as P-toluenesulfonate of N,N-dimethylaniline, α-naphthylamine hydrochloride, etc. These include salts and inorganic acid salts. Examples of aromatic hydroxy compounds having a basic group in the molecule include 2-hydroxy-3-naphthoic acid-3'-morpholinopropylamide, 2-hydroxy-3-naphthoic acid-2'-diethylaminoethylamide, and 2-hydroxy-3-naphthoic acid-2'-diethylaminoethylamide. -3-naphthoic acid-3-
Piperidinopropylamide, 2-hydroxy-3
-naphthoic acid-3'-piperidinopropylamide,
2-Hydroxy-3-naphthoic acid-P-(3'-
N'-dianoguanidinopropyl)oxyanilide, P-(3'-morpholinopropyl) salicylate
Oxyanilide, 1-naphthol-4-sulfonic acid-3'-diethylaminopropylamide, 8-hydroxyquinoline-4-sulfonic acid-2'-diethylaminoethylamide, and organic carbons of amines that generate basicity when heated. Aromatic hydroxy compounds having residues such as acid salts [e.g. 2-
trichloroacetate of hydroxy-3-naphthoic acid-3'-monopholinopropylamide, phenylthioacetate of 1-naphthol-4-sulfonic acid-3'-diethylaminopropylamide, etc.). In the present invention, an image of any tone can be obtained by using two or more of the above coupling components in combination. In the present invention, a poorly water-soluble or water-insoluble basic substance, a substance that generates an alkali upon heating (hereinafter referred to as a basic substance), etc. can be used as a coloring aid. Basic substances used as coloring aids include inorganic and organic ammonium salts, organic amines and amides, urea and thiourea and their derivatives, thiazoles, pyrroles,
Pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines,
triazoles, morpholines, piperidines,
Nitrogen-containing compounds such as amidines, formazines, and biridines, and specific examples thereof include 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,
Examples include N,N'-dibenzylpiperazine, 4,4-dithiomorpholine, morpholinium trichloroacetate, 2-amino-benzothiazole, 2-benzoylhydrazino-bendithiazole, and the like. Two or more of these basic substances can also be used in combination. The coupling agent and/or the basic substance can be contained in a separate microcapsule from the diazo compound or simply added to the layer of the microcapsule containing the diazo compound. When not contained in microcapsules, it is preferable to finely disperse it in the form of particles. Incidentally, in the case of a coupling agent that can couple with a diazo compound only in a basic atmosphere, it is natural that the diazo compound and the coupling agent can be contained in the same microcapsule. In the present invention, the amount of diazo compound applied is
The amount of the coupling agent is preferably 0.05 to 5.0 g/ ^m2 , and the amount of the coupling agent is 0.1 to 10 g/m2 per 1 part by weight of the diazo compound.
The basic substance is preferably used in an amount of 0 to 20 parts by weight. In the present invention, a polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as a vinyl monomer) to be encapsulated together with a diazo compound in a microcapsule is defined as having at least one ethylenically unsaturated bond (vinyl group) in its chemical structure. , vinylidene groups, etc.), and has chemical forms such as monomers, prebolimers, that is, 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. Examples of the salts of unsaturated carboxylic acids include sodium salts 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-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol Examples include diacrylate, pentaerythritol triacrylate, pentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, and polyester acrylate oligomer. Examples of methacrylic acid esters include tetramethylene glycol dimethacrylate, trimethylene 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-
Examples include [p-acryloxyethoxy)phenyl]dimethylmethane. Examples of itaconic acid include ethylene glycol diitaconate, propylene glycol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, and sorbitol tetrataconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaeryloritol dicrotonate, and sorbitol tetracrotonate.
Isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, sorbitol tetraisocrotonate, and the like. Examples of maleic esters include ethylene glycol maleate, 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 (However, R and R' represent H or CH _3. ) Preferred vinyl monomers used in the present invention include monofunctional or polyfunctional methacrylates and polyfunctional methacrylates. acrylate. <<Operation>> When a diazo compound is used as a coloring agent as in the present invention, fixation can be achieved by exposing the entire surface of the recording material after thermal recording. In this case, the skin becomes stained brown due to decomposition of the diazo compound, but the polymerizable compound having an ethylenically unsaturated bond used in the present invention prevents the above-mentioned skin stain, although the details of its action are not clear. can do. The amount of vinyl monomer used in the present invention is 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, per 1 part by weight of the diazo compound. The above-mentioned vinyl monomer can not only prevent background staining during photofixing, but also maintain good thermochromic properties and develop color at room temperature by incorporating it into the core of microcapsules together with a diazo compound. Prevent contact between substances involved in the reaction,
It also contributes to improving shelf life. In this case, in addition to the above vinyl monomer, a part thereof,
By replacing water with an organic solvent that is insoluble in water,
It is possible to increase the reactivity during heating recording and improve the color density of the recording material. As the organic solvent that can be used for this purpose, it is preferable to use one with a boiling point of 180° C. or higher because evaporation loss during raw storage is small. Organic solvents that can be preferably used in the present invention include phosphoric acid esters, phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane, etc. can be,
Specific examples include tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilaurate phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, and sebacic acid. Dioctyl, dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane, 2 ，
Examples include 4-di-tert-aminophenol and N,N-dibutyl-2-butoxy-5-tert-octylanilic acid. Among these, ester solvents such as diethyl phthalate, dibutyl phthalate, tricresyl phosphate, and dibutyl maleate are particularly preferred. In addition, the organic solvent is used as a core material for emulsified droplets (diazo compounds, vinyl monomers, organic solvents,
It is preferably contained in the capsule wall-forming substance in an amount of 10 to 70% by weight, particularly 20 to 55% by weight. Next, the microcapsules used in the present invention will be explained in detail. The microcapsules that can be used in the present invention can be appropriately selected from known ones, but it is especially important to select ones that are not easily destroyed by heat or pressure. It is preferable from the viewpoint of ease of handling. Such preferable microcapsules are those in which reactive substances present in the core and outside of the microcapsules are heated to permeate the microcapsule wall and react. Therefore, the capsule walls of the microcapsules used in the present invention do not necessarily need to be melted by heat, and it is preferable that the walls have a higher melting point because they have better shelf life. In addition, as the size of the microcapsules increases, the thermal contact between the core substance of the microcapsules and other substances decreases with short-term heating, resulting in a decrease in color density, so the average particle size is preferably 20μ or less, especially It is preferably 8μ or less. Next, the method for manufacturing the microcapsules used in the present invention will be described in detail. The microcapsules used in the present invention are preferably made by emulsifying a core material containing a diazo compound and then forming a wall of a polymer material around the oil droplets. In this case, the reactant forming the polymeric substance is added to the interior of the oil droplet and/or to the exterior of the oil droplet. Specific examples of such polymeric materials include polyurethane, polyurea, polyamide,
Polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene,
Examples include styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, and the like. Two or more of these polymeric substances can also be used in combination. Among the above-mentioned polymeric substances, polyurethane, polyurea, polyamide, polyester, and polycarbonate are preferred in the present invention, and polyurethane and polyurea are particularly preferred. The microcapsule wall using the above-mentioned polymeric substance is particularly effective when using a microencapsulation method by polymerizing a reactant from inside the oil droplet. That is, when this method is used, it is possible to obtain capsules having a uniform particle size and excellent shelf life, which are suitable as recording materials, within a short period of time. Such techniques and specific examples of compounds are described in 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 that reacts with it to form the capsule wall (e.g. polyol, polyamine) are mixed into the oily liquid to be encapsulated and emulsified and dispersed in water. , Next, by increasing the temperature, a polymer formation reaction occurs at the oil droplet interface to form a microcapsule wall. At this time, an auxiliary 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 to be reacted with it, US Pat.
No. 3468922, No. 3773695, No. 3793268, Special Publication No. 1973
−40347, No. 49-24159, JP-A-48-80191,
No. 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 react with water to form a polymer film. Further, by combining polyvalent isocyanate, which is the first wall film-forming substance, and polyol, which is the second wall film-forming substance, the thermal permeability of the reactive substance can be changed arbitrarily. In the present invention, as the polyvalent isocyanate which is the first wall film forming substance, for example, 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'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,
Diisocyanates such as 2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, 4,4',
Triisocyanates such as 4″-triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate, and tetraisocyanates such as 4,4′-dimethyldiphenylmethane-2,2′,5,5′-tetraisocyanate. , an adduct of hexamethylene diisocyanate and trimethylolpropane, an adduct of 2,4-tolylene diisocyanate and trimethylolpropane, an adduct of xylylene diisocyanate and trimethylolpropane, an adduct of tolylene diisocyanate and hexanetriol. Prepolymers, etc. can be used. On the other hand, 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 polyhydroxy compounds with a molecular weight of 5000 or less, which have the following groups (), (), (), or () between two hydroxyl groups in their molecular structure. () Number of carbon atoms 2 to 8 aliphatic hydrocarbon groups

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[C] Here, Ar in (), (), and () represents a substituted or unsubstituted aromatic moiety, and the aliphatic hydrocarbon group in () is one whose basic skeleton is -CnH ₂ n-. and the hydrogen atom may be replaced with another element. Examples of () are 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,
Examples include 1,2,6-trihydroxyhexane, phenylethylene glycol, 1,1,1-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. Examples of () are 4,4-dihydroxy-
Examples include diphenylmethane, 2-(p,p'-dihydroxydiphenylmethyl)benzyl alcohol, an adduct of bisphenol A and ethylene oxide, an adduct of bisphenol A and propylene oxide, and the like. The polyol is preferably used in a proportion of hydroxyl groups of 0.02 to 2 moles per mole of isocyanate groups. When producing microcapsules as described above, water-soluble polymers can be used. Here, water-soluble polymers include water-soluble anionic polymers, nonionic polymers, and amphoteric polymers, and anionic polymers can be either natural or synthetic. For example, -COO- ^,
Examples include those having an SO ₃ ^- group and the like. Specific examples of anionic natural polymers include gum arabic,
Examples include alginic acid, and semi-synthetic products include carboxymethyl cellulose, 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-based) 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% by weight water-soluble liquid. When making microcapsules, they can be made from an emulsion containing 0.2% by weight or more of the ingredient to be microencapsulated. As mentioned above, the microcapsules produced as described above are destroyed by heat and pressure, such as those used in conventional recording materials, and the reactive substance contained in the core of the microcapsules is removed from the outside of the microcapsules. This method does not cause a coloring reaction by bringing reactive substances into contact with each other, but by heating the reactive substances present in the core and outside of the microcapsules, the reaction is caused mainly by permeation through the microcapsule walls. . In this case, if the recording layer contains a compound that lowers the glass transition point of the wall material in order to promote softening of the wall of the microcapsule during heating and make it easier for the reactant to pass through, color development is possible. The temperature can be reduced substantially. Such a glass transition point adjusting agent is preferably one that lowers the glass transition point of the wall material of the microcapsules to 80 to 150°C, particularly one that lowers it to 100 to 130°C. Specific examples include, for example, hydroxyl compounds, carbamate ester compounds, aromatic methoxy compounds, and the like. Some of these compounds not only lower the glass transition point of the microcapsule wall material, but also lower the melting point of coupling components and basic substances. This is particularly effective as it further reduces the These compounds are introduced into the recording layer in the same way as basic substances. 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 added. Similarly, metal soaps can also be added to prevent statesking. The amount used is 0.2-7g/ ^m2 . Furthermore, a heat-melting substance can be added to the heat-sensitive recording material of the present invention in order to increase the heat recording speed. Such thermofusible substances are substances with a melting point of 50°C to 150°C that are solid at room temperature but melt when heated with a thermal head, and include substances that dissolve diazo compounds, coupling agents, or basic substances. It is. The heat-fusible substance is dispersed in particles of 0.1-10μ and used in an amount of 0.2-7g/m ² solids. Specific examples of the heat-melting substance include fatty acid amides, N-substituted fatty acid amides, ketone compounds, N-substituted carbamate compounds, urea compounds, and esters. Substances not contained in microcapsules are preferably used after being dispersed in solid form using a sand mill or the like. In this case, they are each dispersed separately or simultaneously in an aqueous polymer solution. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules. In this case, the concentration of the water-soluble polymer is 2 to 30% by weight, and the amount of the material to be dispersed in the water-soluble polymer solution is 5 to 40% by weight. The dispersed particle size is
It is preferably 10μ or less. The heat-sensitive recording material of the present invention can be coated using a suitable binder. As a binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose,
Hydroxypropyl cellulose, gum arabic,
Various emulsions such as gelatin, polyvinylpyrodrine, 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 as solid content. In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, etc. can be added as acid stabilizers. The heat-sensitive recording material of the present invention is prepared by preparing a coating liquid by dispersing microcapsules containing a diazo compound and an organic solvent and other components in a solid state (which can also be microcapsulated) or by dissolving them as an aqueous solution and then mixing them. , coated on a support such as paper or synthetic resin film by a coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating, spray coating, dip coating, etc., and dried to a solid content of 2.5 to 15 g. /m ² of heat-sensitive layer. 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 alkyl ketene dimer (described in JP-A No. 55-14281) is recommended in terms of storage stability over time. It is advantageous. In addition, in order to prevent the coating from penetrating the paper and improve the contact between the recording heat head and the heat-sensitive recording layer,
Steckigt size degree/(meter basis weight) ² ≧3×10 ^- as described in No. 57-116687
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 as described in JP-A No. 58-136492, and paper with a density as described in JP-A-58-69091
Paper with an optical contact ratio of 0.9 g/cm ³ or less and 15% or more, from pulp beaten to a Canadian standard freeness (JIS P8121) of 400 c.c. or more as described in JP-A-58-69097. A paper made by paper making to prevent penetration of coating liquid, described in JP-A No. 58-65695, which improves color density and resolution by using the glossy side of base paper made by a Yankee machine as the coating surface, JP-A-58-65695. 59−
Papers described in No. 35985, in which base paper is subjected to corona discharge treatment to improve 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 the unreacted coloring agent. . In addition, it can also be used as a heat-developable copying paper. <<Effects of the Invention>> Since the heat-sensitive recording material of the present invention contains at least a diazo compound in microcapsules, the recording material has good shelf life, and the polymerizable compound having an ethylenically unsaturated bond is not included in the diazo compound. Since the ink is allowed to coexist with the toner, there is no background staining when photofixing is performed, and the recorded image can also be stored in good condition after recording. It goes without saying that these effects of the present invention can be similarly obtained in multicolor thermosensitive recording materials using one or more color formers. Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited thereby.
Note that "parts" indicating the amount added represent "parts by weight." 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 a diazo compound in the core substance was obtained. (diazo compound)

Next, 10 parts of 2-hydroxy-3-naphthoic acid 3'-morpholinopropylamide and 15 parts of p-benzyloxyphenol were added to 100 parts of a 5% polyvinyl alcohol aqueous solution, and dispersed in a sand mill for about 24 hours.
A dispersion of a coupling component and p-benzyloxyphenol having an average particle size of 2 μm was obtained. A coating solution was prepared by adding 36 parts of a dispersion of a coupling component and p-benzyloxyphenol 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 10 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.).
Next, the entire surface was exposed using Ricopy Super Dry 100 (manufactured by Ricoh Co., Ltd.) and fixed. 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. Tested in the same manner. The results are shown in Table 1.

[Table] Example 7 In Example 1, the following co-dispersion was prepared instead of the co-dispersion of the coupling component and p-benzyloxyphenol. 2-Hydroxy-3-naphthoic acid anilide 10
10 parts of triphenylguanidine and 20 parts of p-benzyloxyphenol were added to 120 parts of 5% polyvinyl alcohol, and the same operation as in Example 1 was carried out to obtain a dispersion. A coating solution was prepared by adding 80 parts of a dispersion of a coupling component to 50 parts of a capsule of a diazo compound, and a dry recording material was obtained using a coating rod. Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethylolpropane trimethacrate was omitted and 24 parts of tricresyl phosphate was used instead. The test results are shown in Table 1. Comparative Example 2 In Example 1, except for trimethylolpropane trimethacrylate and tricresyl phosphate,
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 24 parts of dibutyl phthalate was used instead. The test results are shown in Table 1. Comparative Example 3 A thermosensitive capsule was prepared in the same manner as in Example 1, except that 0.3 parts of benzoin methyl ether was added as a photopolymerization initiator to the capsule liquid containing the diazo compound and vinyl monomer in Example 1 to prepare a capsule liquid. Obtained recording materials. The test results are shown in Table 1. Comparative Example 4 A thermosensitive capsule was prepared in the same manner as in Example 2, except that 0.3 parts of benzoin methyl ether was added as a photopolymerization initiator to the capsule liquid containing the diazo compound and vinyl monomer of Example 2 to prepare a capsule liquid. Obtained recording materials. The test results are shown in Table 1. Comparative Example 5 Thermosensitive was prepared in the same manner as in Example 3, except that 0.3 parts of benzoin methyl ether was added as a photopolymerization initiator to the capsule liquid containing the diazo compound and vinyl monomer of Example 3 to prepare a capsule liquid. Obtained recording materials. The test results are shown in Table 1. Comparative Example 6 In the capsule liquid containing the diazo compound and vinyl monomer of Example 1, 2,
2-dimethoxy-2-phenylacetophenone
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 0.5 part of the solution was added to prepare a capsule liquid. The test results are shown in Table 1. Comparative Example 7 In the capsule liquid containing the diazo compound and vinyl monomer of Example 2, 2,
2-dimethoxy-2-phenylacetophenone
A heat-sensitive recording material was obtained in the same manner as in Example 2, except that 0.5 part of the solution was added to prepare a capsule liquid. The test results are shown in Table 1. Comparative Example 8 In the capsule liquid containing the diazo compound and vinyl monomer of Example 3, 2,
2-dimethoxy-2-phenylacetophenone
A heat-sensitive recording material was obtained in the same manner as in Example 3, except that 0.5 part of the solution was added to prepare a capsule liquid. The test results are shown in Table 1.

【table】

[Table] As is clear from Table 1, (1) Comparative Examples 1 and 2 have considerably high yellow density in the background, whereas Examples 1 to 7 of the present invention have low yellow density; (2)
The blue density of the background part after the deterioration test of Comparative Examples 3 to 8 is higher than the blue density of Examples 1 to 7 of the present invention in all cases, indicating that the more manufactured heat-sensitive material is superior. has been proven.

Claims (1)

[Claims] 1. In a heat-sensitive recording material in which a recording layer containing at least a diazo compound and a coupling component is provided on a support, the diazo compound is used together with a polymerizable compound that does not contain a photoinitiator and has an ethylenically unsaturated bond. A heat-sensitive recording material characterized by being contained in microcapsules.