JPH0533673B2 - - 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. <<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 or heating after recording or adhesion of solvents, staining the recorded image. As a heat-sensitive recording material that solves these drawbacks, a diazo color-forming heat-sensitive recording material has been proposed in recent years (for example, Japanese Patent Application Laid-open No. 57-123086, Journal of the Image Electronics Engineers of Japan, 11 , 290 (1982)). , thermal recording on a recording material using a coupling component and a basic component (including substances that become basic with heat), followed by light irradiation to decompose unreacted diazo compounds and stop color development. It is.
It is true that with this method, it is possible to stop color development (hereinafter referred to as fixing) in areas that do not require recording, but this recording material also gradually undergoes pre-coupling during storage, resulting in undesirable coloring (fogging). ) has the disadvantage of occurring. Therefore, 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).
Even in this case, there are disadvantages in that the storage stability (hereinafter referred to as raw storage stability) of the recording material is still insufficient and the thermal coloring property is 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, as described in the above-mentioned Japanese Patent Application Laid-Open No. 123086/1986). Although this method improves raw storage stability, the thermal color development is greatly reduced, and it cannot respond to high-speed recording with a short pulse width, making it impractical. In addition, 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. 142636/1983).
It is also known to isolate it from other components by encapsulating it with a hydrophobic polymeric substance (Japanese Patent Application Laid-open No. 192944/1983). However, these encapsulation methods involve dissolving the wax or polymer substance in its solvent and dissolving or dispersing the coloring component in the solution to form a capsule. This is different from the concept of a normal capsule covered with a shell. Therefore, when the coloring component is dissolved and formed, the coloring component does not become the core material of the capsule, but mixes uniformly with the encapsulating material, and pre-coupling gradually progresses at the wall interface of the capsule during storage. In addition, it has the drawback that the raw storage stability is not fully satisfied, and the coloring reaction does not occur unless the capsule wall is thermally melted, so the thermal coloring property is reduced. There was a manufacturing problem in that the solvent used to dissolve the liquid had to be removed. As a heat-sensitive material that solves these problems, at least one of the components involved in the coloring reaction is used as a core material, and a wall is formed around this core material by polymerization to form a microcapsule. 58−
65043 Specification) A heat-sensitive recording material has been proposed. <<Problems to be Solved by the Invention>> However, even with heat-sensitive recording materials produced by this microencapsulation method, the fastness of printed images to light and heat after photofixing is insufficient;
Further, since there is a drawback that the unprinted area has a high yellowish tinge, further improvements have been required. Therefore, a first object of the present invention is to provide a heat-sensitive recording material in which a printed image can be fixed and the non-printed areas have a high degree of whiteness. A second object of the present invention is to provide a heat-sensitive recording material in which a thermochromic image after fixing has good fastness to light and heat. A third object of the present invention is to provide a heat-sensitive recording material that is excellent in all of raw storage stability, image quality, and image storage stability. A fourth 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 heat-sensitive layer having a diazonium salt and a coupler is provided on a support, in which the heat-sensitive layer is o-tert-
This was achieved by a heat-sensitive recording material containing at least one selected from butylphenol and o-tert-butylphenol derivatives. O-tert-butylphenol and its derivatives used in the present invention are hindered phenol compounds that function as a dye image stabilizer and background yellowing preventive agent, and among them, preferred ones are represented by the following general formula. . General formula () General formula () In the formula, R1, R2, and R3 are hydrogen atoms, alkyl groups,
An aryl group, an alkoxy group or a halogen atom,
These may be the same or different. Among these substituents, the alkyl group, aryl group, and alkoxy group may further have a substituent. Y is -O-, -S-,

[Formula] It is an alkylene group or an arylene group, and the alkylene group and the arylene group may further have a substituent, and in this case, substitution with o-tert-butylphenol is particularly preferred. As a specific example of the general formula (), for example, 2,6
-di-tert-butyl-p-cresol, 2,6-
Di-tert-butylphenol, 2,4-dimethyl-tert-butylphenol, 3-tert-butylphenol
4-hydroxyanisole is mentioned. As a specific example of the general formula (), for example, 2,
2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-
methyl-6-tert-butylphenol), 4,4'-
Methylenebis(2,6-di-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,
n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate,
Pentaerythrityl-tetrakis [3-(3,5
-di-tert-butyl-4-hydroxyphenyl)
Propionate, Bis-[3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)-butyric acid] glycol, Bis-[2-(2-hydroxy-
5-methyl-3-tert-butylbenzyl)-4-
Methyl-6-tert-butylphenyl] terephthalate, 4,4'-thiobis(3-methyl-6-tert
-butylphenol), 4,4'-thiobis(2-
methyl-6-tert-butylphenol) and the like. These compounds may be added in the form of fine particles, but if the diazonium salt or coupler is microencapsulated, they can be added inside the microcapsule or both inside and outside the microcapsule. be. When added in the form of fine particles, the amount is preferably about 0.05 to 20 parts by weight, particularly preferably 0.2 to 5 parts by weight, per 1 part by weight of the diazonium salt. When added into microcapsules, the amount is preferably about 0.01 to 5 parts by weight, particularly preferably 0.05 to 1 part by weight, per 1 part by weight of the diazonium salt. It may also be used in combination with other anti-fading agents. The diazo compound used in the present invention has the general formula
ArN ₂ +X ^- (where Ar represents an aromatic moiety,
N ₂ ⁺ represents a diazonium group and X ^- represents an acid anion. ) is a diazonium salt represented by
It is a compound that develops color by causing a coupling reaction with a coupling component and can be decomposed by light. Specifically, the aromatic moiety is preferably one of the following general formula. 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 monophorino group, a piperidino group, a pyrrolidino group, etc. are preferred. Diazonium compounds that form salts include 4-
Diazo-1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-
1-dipropylaminobenzene, 4-diazo-1
-Methylbenzylaminozene, 4-diazo-1-
Dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methylbenzene, 4-diazo-1- Benzoylamino-2,5-diethoxybenzene, 4-diazo-1
-morpholino-2,5-diethoxybenzene, 4
-Diazo-1-morpholino-2,5-dibutoxybenzene, 4-diazo-1-anilinobenzene,
4-Diazo-1-tolylmercapto-2,5-
Examples include diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-diethoxybenzene, and 4-diazo-1-pyrrolidino-2-ethylbenzene. Specific examples of acid anions include CnF ₂ n+ ₁ COO ^- (n is an integer of 3 to 9), CmF ₂ m+ ₁ SO ₃ ^- (m is an integer of 2 to 8), (ClF ₂ l+ ₁ SO ₂ ) ₂ CH ^- (l is an integer from 1 to 18), 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 it causes less 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 one that couples with a diazo compound (diazonium salt) to form a dye. As a specific example,
For example, resorcinol, phloroglycin, 2,3-
Sodium dihydroxynaphthalene-6-sulfonate, 1-hydroxy-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-
Dihydroxy-6-sulfanylnaphthalene, 2
-Hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid-
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',Four',
6′-Trichlorophenyl)-3-benzamide-
5-pyrazolone, 1-(2',4',6'-trichlorophenyl)-3-anilino-5-pyrazolone, 1-
Examples include phenyl-3-phenylacetamido-5-pyrazolone. 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. Examples of the basic substance include a poorly water-soluble or water-insoluble basic substance and a substance that generates alkali when heated. 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,
Examples include 2-amino-benzothiazole and 2-benzoylhydrazino-benzothiazole. Two or more of these basic substances can also be used in combination. The microcapsules used in the present invention can not only be destroyed by heat or pressure as used in conventional recording materials, but also be destroyed by heating to destroy reactive substances present in the core and outside of the microcapsules. It also includes microcapsules in which the microcapsules are able to penetrate the microcapsule wall and react. From the viewpoint of thermochromic properties, the latter microcapsules are preferred. The case where this latter microcapsule is used will be explained in detail below. Microcapsules are impermeable to substances at room temperature, but become permeable when heated, by dissolving or dispersing the reactive substance contained in the core material of the microcapsule in an organic solvent that is insoluble in water, and emulsifying it. Microcapsule walls are formed around oil droplets by polymerization. In this case, the organic solvent preferably has a boiling point of 180°C or higher. Specifically, phosphoric acid esters, 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, dilauryl phthalate, dicyclohexyl phthalate,
Butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, trioctyl trimellistate, acetyl triethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropyl naphthalene, 1,
Examples include 1'-ditolylethane, 2,4-di-tert-aminophenol, N,N'-dibutyl-2-butoxy-5-tert-octylaniline, and the like.
Among these, ester solvents such as dibutyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are particularly preferred. A reactant forming a polymeric material as the microcapsule wall is added inside the oil droplet and/or outside 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 polyurethanes, polyureas, polyamides, polyesters, polycarbonates, particularly preferred are polyureas and polyurethanes. The method of making the microcapsule wall of the present invention is particularly effective when using a microencapsulation method by polymerizing a reactant from inside an oil droplet. That is, since a uniform particle size is formed within a short period of time, it is preferable for producing a heat-sensitive recording material with excellent shelf life. 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 the capsule wall material, a polyvalent isocyanate and a second substance that reacts with it to form the capsule wall (such as a polyol) are mixed into the oily liquid to be encapsulated, emulsified and dispersed in water, and then By increasing the temperature, a polymer formation reaction occurs at the oil droplet interface, forming a 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 to be reacted 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. 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. or,
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 triisocyanates;
4,4'-dimethylphenylmethane-2,2',5,
Tetraisocyanates such as 5'-tetraisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, adducts of 2,4-tolylene diisocyanate and trimethylolpropane, adducts of xylylene diisocyanate and trimethylolpropane, tolylene diisocyanate and isocyanate prepolymers such as adducts of hexanetriol. Examples of the polyol as the second wall-forming substance include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, and hydroxy polyalkylene ethers. Preferred polyols include the following (), (),
Polyhydroxy compounds having a molecular weight of 5,000 or less and having () or () groups in their molecular structure can be mentioned. () 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 -CnH ₂ n-,
Hydrogen groups may be substituted with other elements. To give a specific example, as an example of (),
Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-
heptanediol, 1,8-octanediol,
Propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-
Propanediol, 2,4-pentanediol,
2,5-hexanediol, 3-methyl-1,5
-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,6-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. Polyol has 1 isocyanate group
It is preferable to use the hydroxyl group at a ratio of 0.02 to 2 moles per mole. When manufacturing microcapsules, water-soluble polymers can be used. The water-soluble polymer in this case may be any water-soluble anionic polymer, nonionic polymer, or amphoteric polymer. 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 examples of anionic natural polymers include gum arabic and alginic acid, and examples of 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. Among these, the preferred water-soluble polymer is polyvinyl alcohol, and those having a degree of saponification of 75% or more and a degree of polymerization of 300 to 2,400 are preferred. These water-soluble polymers are used as a 0.01 to 20% by weight aqueous solution. The particle size of the 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 with a thermal head is performed from the coated layer side, to avoid pressure fog.
It is preferably 8μ or less. Of the diazo compound, the coupling component, and the basic substance used if necessary, which are the main components of the heat-sensitive layer of the heat-sensitive recording material of the present invention, any one of them may be used as the core material of the microcapsules.
The species or three species can also be used as core materials for microcapsules. When two types are contained in the core material of microcapsules, they may be in the same microcapsule or in separate microcapsules.
Further, when three types are contained in the core material of 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. The hindered phenol compound used in the present invention may be present in the core of the microcapsule or outside. When manufacturing microcapsules, they can be made from an emulsion containing 0.2% by weight or more of the component to be microencapsulated. The diazo compound used in the present invention, the coupling component, and the basic substance used if necessary may be contained in the inside of the microcapsule or in the heat-sensitive layer outside the microcapsule. On the other hand, it is preferable to use the coupling component in a proportion of 0.1 to 10 parts by weight and the basic substance in a proportion of 0.1 to 20 parts by weight. Further, it is preferable to apply the diazo compound in an amount of 0.05 to 5.0 g/m ² . When the diazo compound, 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. In this case, the concentration of the water-soluble polymer is 2 to 30% by weight, and the diazo compound, coupling component, and basic substance are each 5 to 40% by weight with respect to this water-soluble polymer solution.
It is invested so that it becomes. The dispersed particle size is preferably 10μ or less. A hydroxy compound, a carbamate 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 thermal color development. These compounds can lower the melting point of the coupling component or basic substance or improve the thermal permeability of the microcapsule wall, and as a result, the practical concentration during thermal recording can be increased. Conceivable. Specific examples of hydroxy compounds include p-t-
Butylphenol, p-t-octylphenol, p-α-cumylphenol, p-t-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-diphenylmethyl)phenol, o-phenylphenol, ethyl p-hydroxybenzoate, p-hydroxy Propyl benzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-methoxyphenol, p-butoxyphenol, p-heptyloxyphenol, p-benzyloxyphenol,
Dimethylvanillin 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-
Phenol compounds such as bis(4-hydroxyphenyl)-heptane vanillin, 2-t-butyl-4-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-xylylene diol, 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,
Alcohol compounds such as Specific examples of carbamate ester compounds include N-phenylcarbamate ethyl ester, N-phenylcarbamate benzyl ester, N-phenylcarbamate phenethyl ester, carbamate benzyl ester, carbamate butyl ester, and carbamate. Examples include isopropyl ester and the like. Specific examples of aromatic methoxy compounds include 2
-methoxybenzoic acid, 3,5-dimethoxyphenylacetic acid, 2-methoxynaphthalene, 1,3,5-
Examples include trimethoxybenzene, p-dimethoxybenzene, p-benzyloxymethoxybenzene, and the like. Specific examples of organic sulfonamides include p-toluenesulfonamide, o-toluenesulfonamide, p-ethylbenzenesulfonamide, o-
Ethylbenzenesulfonamide, m-ethylbenzenesulfonamide, benzenesulfonamide,
p-Toluenesulfonamide, N-(p-methoxyphenyl)-p-toluenesulfonamide, N-
(o-methoxyphenyl)-p-toluenesulfonamide, N-(p-chlorophenyl)-p-toluenesulfonamide, N-(o-chlorophenyl)
-p-toluenesulfonamide, N-(p-tolyl)-p-toluenesulfonamide, N-(o-hydroxyphenyl)-p-toluenesulfonamide, N-benzyl-p-toluenesulfonamide, N-( 2-phenethyl)-p-toluenesulfonamide, N-(2-hydroxyethyl)-p-toluenesulfonamide, N-(3-methoxypropyl)-p-toluenesulfonamide, methanesulfonamide, N-(p- tolyl) sulfonamide, N-(o-tolyl) sulfonamide, N-(p
-methoxyphenyl)sulfonamide, N-(o
-methoxy)sulfonamide, N-(p-chlorophenyl)sulfonamide, N-(o-chlorophenyl)sulfonamide, N-(2,4-xylyl)sulfonamide, N-(p-ethoxyphenyl)sulfonamide, N-benzylmethanesulfonamide, N-(2-phenoxyethyl)methanesulfonamide, 1,3-bis(methanesulfonylamino)benzene, 1,3-bis(p-toluenesulfonylamino)propane, etc. It is not limited. These compounds can be used by making microcapsules together with the core material of the microcapsules, or by being added to the coating solution of the heat-sensitive recording material and existing outside the microcapsules. is preferred. In either case, the amount used is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 1 part by weight of the coupling component, and can be selected as appropriate to adjust the coloring density to a desired level. 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 yellowing of the background after photofixing. Vinyl monomer is a compound that has at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and is a compound that has at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and is a compound that has monomers, prepolymers, dimers, trimers, and other oligomers. They have chemical forms such as mixtures thereof and copolymers thereof. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, amides of unsaturated carboxylic acids and aliphatic polyhydric amine compounds, and the like. 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 by being contained in the core material of the microcapsule together with the diazo compound, but at this time, part or all of the organic solvent used as the solvent (or dispersion medium) for the core material can be replaced with the vinyl monomer. In this case, it is not necessary to add enough to harden the core material. When the heat-sensitive recording material of the present invention contains a diazo compound as a core material, by containing a coupling reaction deactivator outside the microcapsules, the diazo compound present in the aqueous phase and the diazo compound in the incomplete capsules can be removed. The compound (i.e., the diazo compound that is not completely blocked by the capsule wall) and the coupling reaction quencher react to cause the diazo compound to lose its coupling reaction (coloring reaction) ability, thereby preventing fogging. can. The coupling reaction deactivator may be any substance that reduces the coloring of a solution containing a diazo compound, and the diazo compound is dissolved in water or an organic solvent, and then other substances dissolved in water or an organic solvent are added to the diazo compound. Selection can be made by adding the compound and observing the change in color of the diazo compound. Specifically, hydroquinone, sodium bisulfite, potassium nitrite, hypophosphorous acid, monochloride
Examples include tin and formalin. Besides this, KH
The Aromatic Diazo by Sawn ders
Compounds and Their Technical
Applications” MC, MA (Cant ab.) B.Sc.
(London), published in 1949, pages 105-306. The coupling reaction quencher is preferably one that has little coloring itself and has few side effects.
Particularly preferred are water-soluble substances. The coupling reaction quencher is used to the extent that it does not inhibit the thermal coloring reaction of the diazo compound, but it is usually used in the range of 0.01 to 0.02 mol, particularly in the range of 0.02 to 1 mol, per 1 mol of the diazo compound. It is preferable to use within a range. The coupling reaction deactivator used in the present invention is
It can be used by dissolving microcapsules containing a diazo compound in a solvent and then adding a coupling agent or a basic substance to a dispersion solution, or a mixture thereof. It is preferable to use it in the form of an aqueous solution. 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, calcium carbonate,
Fine powders such as styrene beads, urea-melamine resin, etc. can be used. Similarly, metal soaps can also be used to prevent statesking. The usage amount of these is 0.2 to 7g/m ²
is appropriate. 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. Such a heat-melting substance is a substance with a melting point of 50 to 150°C that is solid at room temperature and melts when heated with a thermal head, and is a substance that dissolves a diazo compound, a coupling component, or a basic substance. The heat-melting substance is dispersed in the form of particles of 0.1 to 10μ, with a solid content of 0.2
Used in amounts of ~7 g/ ^m2 . 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 using a suitable binder. As a binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose,
Bidroxypropyl 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, pyrophosphoric acid, etc. can be added as acid stabilizers. The heat-sensitive recording material of the present invention can be produced by preparing a coating solution containing a diazo compound, a coupling component, a basic substance, other additives, etc., and coating it on a support such as paper or synthetic resin film by bar coating, blade coating, or air knife coating. It is manufactured by applying and drying by a coating method such as coating, gravure coating, roll coating, spray coating, or dip coating to form a heat-sensitive layer having a solid content of 2.5 to 25 g/m ² . Another method is to add the main component of the coupling component, a basic substance, and other additives as the core material of the microcapsules, or to form a coating liquid by dispersing them as a solid or dissolving them as an aqueous solution and then mixing them. Making,
A precoat layer with a solid content of 2 to 10 g/m ² is provided by coating and drying on a support, and a diazo compound as a main component and other additives are further added thereon as a core material of microcapsules, or It is also possible to form a laminate type in which a coating layer of 1 to 15 g/m ² is formed by applying a coating liquid prepared by solid dispersing or dissolving it as an aqueous solution and then mixing it and drying it. The laminated heat-sensitive recording material may have a layered layer in the reverse order, and the coating method may be sequential coating or simultaneous coating of the laminated layers. It is also possible to provide an intermediate layer on the support as described in Japanese Patent Application No. 59-177669, and then apply the heat-sensitive layer. 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. <<Effects of the Invention>> Although the heat-sensitive recording material of the present invention can obtain high image density, it has good raw storage stability and image storage stability after recording, and also has good coloring of the background area after photofixing. Since the density is low, it is particularly effective for long-term storage of recorded images. The shelf life of the photosensitive material and the shelf life of recorded images can be further improved by microencapsulating at least one of the compounds involved in color development. <<Example>> Examples are shown below, but the present invention is not limited thereto. Note that "parts" indicating the amount added represent "parts by weight." Example 1 To 100 g of compound A, 200 g of 5% polyvinyl alcohol (PVA205: trade name manufactured by Kuraray Co., Ltd.) aqueous solution was added.
g was added and dispersed in a ball mill for 24 hours to obtain Solution A. 18g of compound B-1, 2g of compound B-2
g, 20 g of compound C and 60 g of compound D-1.
% polyvinyl alcohol aqueous solution is added,
The mixture was dispersed in a ball mill for 24 hours to obtain liquid BD. Next, 600 g of water was added to 400 g of minor calcium carbonate and dispersed with a dissolver to obtain a pigment liquid. Furthermore, 170 g of a 5% polyvinyl alcohol aqueous solution was added to 30 g of Compound E-1, and the mixture was milled with a ball mill for 24 hours.
Liquid E was obtained by time-dispersing. Prepare a coating liquid by measuring 2 parts of liquid A, 10 parts of liquid B-D, 5 parts of pigment liquid, and 3 parts of liquid E, and apply on high-quality paper so that the coating amount after drying is 8 g/m ² . Bar coated. Drying was performed at room temperature to obtain a thermosensitive recording material (1). ≪Test method≫ Heat recording was performed on the obtained heat-sensitive recording material using a G-mode thermal printer (UF-2: manufactured by Matsushita Electric Transmission Co., Ltd.), and then a Ricopy Super Dry 100 (Ricoh
Co., Ltd.), the entire surface was exposed and fixed. The density of the obtained recorded image was measured using a Macbeth reflection densitometer. In addition, the yellow density of the background portion was also measured in the same manner. The results are shown in Table 1. On the other hand, when thermal recording was attempted again on the fixed portions, it was confirmed that the images were fixed without being recorded. Next, in order to examine the shelf life of the heat-sensitive recording material, we performed a forced deterioration test by storing the heat-sensitive recording material in a dark place for 24 hours at a temperature of 40°C and a relative humidity of 90% RH. The fog after printing was measured using a Macbeth reflection densitometer, and changes in fog density were measured.
After fixing, in order to check the stability of the dye image and the yellowing of the background, the recorded image obtained by fixing was measured using a xenon fade meter (Suga Test Instruments, FAL-25AX-
After 24 hours of irradiation with the HC type, the density of the recorded image area and the background area was measured. The results are shown in Table 1. The compounds used for sample preparation are as follows. Compound A: Diazonium salt Compound B-1: Coupler Compound B-2: Coupler Compound C: Organic basic compound Compound D-1: Color development improver Compound E-1: Hindered phenol compound

[Table] Examples 2 to 4 The same procedure as in Example 1 was performed except that compounds E-2, E-3, and E-4 were used as liquid E in Example 1, respectively, to produce heat-sensitive recording materials (2), ( 3) and (4) are obtained,
A test similar to Example 1 was conducted. The results are shown in Table 1. In addition, compounds E-2, E-3 and E-4 are as follows, respectively. Compound E-2: Hindered phenol compound Compound E-3: Hindered phenol compound Compound E-4: Hindered phenol compound Comparative Example 1 A comparative sample (ratio -1) was obtained in the same manner as in Example 1 except that liquid E was not used. The results of the test conducted in the same manner as in Example 1 are shown in Table 1.
It was as shown in. As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has low background density during recording, image deterioration after recording,
It was demonstrated that both the yellowing of the skin after recording and the shelf life before recording were improved. Example 5 Next, as an example, an example in which Compound A was microencapsulated is shown. 50g of compound A, 150g of methylene chloride,
50 g of tricresyl phosphate, 150 g of trimethylolpropane trimethacrylate, 75% ethyl acetate solution of trimethylolpropane 3:1 adduct of m-xylylene diisocyanate (Takenate
DIION (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.) (200 g) was uniformly mixed to form an oil phase liquid. On the other hand, 600 g of 7% polyvinyl alcohol (PVA217E: degree of saponification 88-89%, degree of polymerization 1700: trade name manufactured by Kuraray Co., Ltd.) was prepared to prepare a water-soluble polymer aqueous solution. Attach a dissolver to a 5 stainless steel pot equipped with a warm bath, add the protective colloid aqueous solution, then add the oil phase solution while stirring the dissolver, and perform emulsification and dispersion until the average particle size becomes approximately 1.5μ when observed with a microscope. Ivy. After the dispersion was completed, stirring was loosened, and hot water at 42°C was poured into the hot bath to carry out the encapsulation reaction at an internal temperature of 40°C for 3 hours. The obtained solution A' was used after removing the diazonium salt that could not be encapsulated with the ion exchange resin. A coating solution was prepared using 5 parts of A' solution, 7 parts, 3.5 parts, and 2.1 parts of B-D solution, pigment solution, and E solution used in Example 1, respectively, and the coating amount after drying on high-quality paper. but
A heat-sensitive recording material (5) was prepared by coating at a density of 10 g/m ² . The results of the test conducted in the same manner as in Example 1 are shown in Table 2.

[Table] Examples 6 to 8 Thermal recording materials (6) to (8) were prepared in exactly the same manner as in Example 1, except that the E liquid used in Examples 2 to 4 was used as the E liquid in Example 5. I got it. The results of the test conducted in the same manner as in Example 1 are shown in Table 2. Example 9 Next, as an example, Compound A and Compounds E-1 to E-4
An example of microencapsulation is shown below. Microencapsulation was carried out in exactly the same manner as in Example 5, except that 5 g of compound E-1 was added to the oil phase solution of Example 5 to obtain A'' liquid, and heat-sensitive recording material (9) was prepared in the same manner as in Example 5. The results of the test conducted in the same manner as in Example 1 are shown in Table 2. Examples 10 to 12 Compounds E-2 and E were used in place of Compound E-1 used in Example 9, respectively. Thermal recording material (10) to
(12) was obtained. The results of the test conducted in the same manner as in Example 1 are shown in Table 2. Comparative Example 2 A comparative sample (ratio-2) was obtained in exactly the same manner as in Example 5, except that liquid E was not used. The results of the test conducted in the same manner as in Example 1 are shown in Table 2. The results in Table 2 show that the effect of hindered phenol is clear even when diazo compounds are microencapsulated, and from these examples,
The effective shelf life of the present invention was demonstrated. Example 13 In preparing liquid B-D, liquid (B-D)' was prepared in exactly the same manner as in Example 1, except that the following color development improver D-2 was used instead of compound D-1. Created. Next, in the same manner as in Example 5, 5 parts of liquid A',
A coating solution was prepared using 7 parts of B-D solution, 3.5 parts of pigment solution, and 2.1 parts of E solution using compound E-1, and coated on high-quality paper so that the coating amount after drying was 10 g/m ² . A thermosensitive recording material (13) was obtained. The results of the test conducted in the same manner as in Example 1 are shown in Table 3. Compound D-2 Examples 14 to 16 Example 13 except that the E liquid used in Examples 2 to 4 was used instead of the E liquid in Example 13.
Thermosensitive recording materials (16) to (14) were obtained in exactly the same manner as described above. The results of the test conducted in the same manner as in Example 1 are shown in Table 3. Comparative Example 3 A comparative sample (ratio-3) was obtained in exactly the same manner as in Example 13, except that Liquid E was not used.

[Table] The results of the test conducted in the same manner as in Example 1 are shown in Table 3. The results in Table 3 also demonstrate that the heat-sensitive recording material of the present invention has excellent performance.
As described above, even if the color development improver is changed, the effectiveness of the present invention does not change, so the effects of the present invention are as follows:
In particular, it has been demonstrated that this can be obtained by adding hindered phenol. Examples 17 to 21 Next, in an example in which Compound (A) was microencapsulated, an example in which Compound E-2 was used to investigate the dependence on the added amount of the hindered phenol compound will be shown. As in Example 5, 5 parts of liquid A', 7 parts of liquids B to D,
Coating liquids were prepared using 0.085 parts, 0.34 parts, 1.7 parts, 5.1 parts, and 10.2 parts of E-liquid using E-2 in 3.5 parts of pigment liquid, and the coating amount after drying on high-quality paper was 10 g/
^heat -sensitive recording materials (17), (18), (19),
(20) and (21) were obtained. The results of the test conducted in the same manner as in Example 1 are shown in Table 4.

[Table] Comparative Example 4 Comparative samples (ratio-
4) was obtained. The results of the test conducted in the same manner as in Example 1 are shown in Table 4.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a heat-sensitive layer containing a diazonium salt and a coupler on a support,
The heat sensitive layer contains o-tert-butylphenol and o-
A heat-sensitive recording material comprising at least one selected from tert-butylphenol derivatives. 2. The heat-sensitive recording material according to claim 1, wherein at least one of the diazonium salt and coupler in the heat-sensitive layer is encapsulated in microcapsules. 3. The heat-sensitive recording material according to claim 2, wherein the diazonium salt is encapsulated in microcapsules.