JPH0410876B2 - - 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, the present invention relates to a heat-sensitive recording material that has excellent storage stability before thermal recording, high color density during thermal recording, and is capable of light fixing 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 Image Electronics Engineers of Japan, 11 , 290 (1982), etc., the recording materials using diazo compounds, coupling components, and basic components (including substances that become basic with heat) are 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 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 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, the heat-sensitive recording materials produced by this microencapsulation method do not always have satisfactory color density, and further improvements have been desired. ``Object of the Invention'' Therefore, the first object of the present invention is to provide a heat-sensitive recording material that has excellent shelf life and 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 purpose of the present inventors is to provide a heat-sensitive recording material in which a recording layer containing at least a diazo compound and a coupling component is coated on a support. The problem was solved by a heat-sensitive recording material characterized by containing either one of them in microcapsules and further containing at least one organic sulfonamide compound in the recording layer. "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. It does not cause a coloring reaction upon contact, but rather allows the reaction to occur primarily through the microcapsule wall by heating the reactive substance present in the core and outside of the microcapsule. That is, the microcapsule wall functions to prevent contact between the diazo component and the coupling component until heating, thereby suppressing unnecessary fogging during raw storage. As a result of various studies on heat-sensitive recording materials using such microcapsules, the present inventors found that the above-mentioned diazo component and coupling component were added to improve color development at low temperatures and to reduce fog during raw storage. In addition, we discovered that it is extremely effective to include an organic sulfonamide compound in the layer.
This means that the present invention has been achieved. That is, when the organic sulfonamide compound of the present invention is used in combination with the microcapsules used in the present invention, the thermal coloring property can be significantly improved compared to when it is not used. Presumably, these compounds lower the melting point of the coupling component and the basic substance added if necessary, and also improve the heat permeability of the microcapsule wall, resulting in a higher practical coloring density. Specific examples of organic sulfonamides include the following compounds. That is, p-toluenesulfonamide, o-toluenesulfonamide,
Benzenesulfonamide, p-toluenesulfonanilide, 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-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, methanesulfonanilide, 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(methanesulnylamino)benzene,
1,3-bis(p-toluenesulfonylamino)
Examples include, but are not limited to, propane. Particularly preferred is p-toluenesulfonamide. The amount of the organic sulfonamide compound of the present invention used is 0.01 to 10 parts by weight per 1 part by weight of the coupling component.
Parts by weight, preferably 0.1 to 5 parts by weight, may be selected as appropriate in order to adjust the desired color initiation temperature. The diazo compound used in the present invention has the general formula
ArN ₂ ⁺ X ^- (where Ar represents an aromatic moiety, and N ₂ ⁺
represents a diazonium group, and X ^- represents an acid anion. ) It is a compound that can develop color by causing a coupling reaction with a coupling component, and can be decomposed by light. Specifically, as the aromatic moiety, those having the following general formula are preferable. 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 (1,
Br, Cl, F). The substituted amino group of Y includes a monoalkylamino group, a dialkylamino group, an arylamino group,
A morpholino group, a piperidino group, 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 CnF _2o+1 COO ^-
(n is an integer from 3 to 9), CmF _2n+1 SO ₃ ^- (m is from 2 to
(ClF _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-sulfanyl Naphthalene, 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. It is preferable to add a basic substance to the layer of the present invention for the purpose of making the system basic and promoting the coupling reaction. As these basic substances, used are sparingly water-soluble or water-insoluble basic substances and substances that generate alkali upon heating. Basic substances include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their dielectrics, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, Examples include nitrogen-containing compounds such as triazoles, 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. The microcapsules of the present invention can be obtained by dissolving or dispersing the reactive substance contained in the core substance in a water-insoluble organic solvent, emulsifying it, and then forming a microcapsule wall around it by polymerization. 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, dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, and dioctyl sebacate. ,
Dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane, 2,4 -Ditertiaryaminophenol, N,N-dibutyl-
Examples include 2-butoxy-5-tertiary octylaniline. Among these, ester solvents such as dibutyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are particularly preferred. The microcapsules of the present invention are made by emulsifying a core material containing a reactive substance 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 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 types of polymeric substances can also be used in combination.
Preferred polymeric materials are polyurethane, polyurea, polyamide, polyester, polycarbonate, and more preferred are 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. That is, it has a uniform particle size 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 (for example, a polyol) that reacts with it to form the capsule wall are mixed into an oily liquid to be encapsulated, emulsified and dispersed in water, and then heated to a temperature. As it rises, 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 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. 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: good storage stability is achieved. 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, xylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1 , 2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, etc., 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. () Aliphatic hydrocarbon group having 2 to 8 carbon atoms 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 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. The polyol is preferably used in a proportion of hydroxyl groups of 0.02 to 2 moles per mole of isocyanate groups. Water-soluble polymers that can be used when making microcapsules may be any of water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. As an anionic polymer,
Both natural and synthetic compounds can be used, including those having -COO ^- , -SO ₃ ^- groups, etc. Specific anionic natural polymers include gum arabic and alginic acid, while 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 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 with a thermal head is performed from the coated layer side, the thickness is preferably 8 μm or less to avoid pressure fog. Regarding the diazo compound and the coupling component, which are the main components used in the present invention, either one of them can be used as the core material of the microcapsule, or two kinds can be used. When it is contained in the core material of two types of microcapsules, they may be the same microcapsule or separate microcapsules. Other ingredients not contained in the core material of the microcapsules are used in the heat-sensitive layer outside the microcapsules. The organic sulfonamide compound of the present invention and the basic substance used if necessary may be present in the core of the microcapsule or outside. Moreover, the organic sulfonamide compound can be contained in the microcapsule wall. However, the basic substance cannot be contained in the core of the microcapsule containing the diazo compound and the coupling component at the same time. When making microcapsules, they can be made from an emulsion containing 0.2wt% or more of the ingredient to be microencapsulated. Whether the diazo compound, coupling component, and basic substance used in the present invention are contained inside the microcapsule or outside the microcapsule, the coupling component is 0.1 to 1 part by weight of the diazo compound. It is preferable to use the basic substance in a proportion of 10 parts by weight and 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 diazo compound, coupling component, organic sulfonamide compound, 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 water-soluble polymer is 2
The diazo compound, coupling component, and basic substance are each added in an amount of 5 to 40 wt% with respect to this water-soluble polymer solution. 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/ ^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 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 pyrolic acid can be added as acid stabilizers. The heat-sensitive recording material of the present invention is produced by preparing a coating solution containing a diazo compound, a coupling component, an organic sulfonamide compound as a main component, and basic substances and other additives, and coating it on a support such as paper or a synthetic resin film. A heat-sensitive layer having a solid content of 2.5 to 25 g/m ² is provided by coating and drying by coating methods such as coating, blade coating, air knife coating, gravure coating, roll coating, spray coating, and dip coating. Another method is to add the coupling component, the main component of the organic sulfonamide compound, a basic substance, and other additives as the core material of the microcapsules, or to disperse them as solids, or to dissolve them as an aqueous solution and then mix and apply. A liquid is prepared, applied onto a support, and dried to form a precoat layer with a solid content of 2 to 10 g/m ² .Furthermore, the main component diazo compound and other additives are added as the core material of the microcapsules. Alternatively, it is also possible to apply a coating liquid made by dispersing it as a solid or dissolving it as an aqueous solution and then mixing it, and then drying it to form a layered layer with a coating layer with a solid content of 1 to 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 heat-sensitive recording material exhibits particularly excellent performance in long-term storage. 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 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 a 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,
- Paper with a density of 0.9 g/cm ³ or less and an optical contact ratio of 15% or more as described in No. 69091, and a paper 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 3.45 parts of the following diazo compound, xylylene diisocyanate and trimethylolpropane (3:
1) 18 parts of the adduct were added to and dissolved in a mixed solvent of 24 parts of tricresyl phosphate and 5 parts of ethyl acetate. This diazo compound solution was mixed with polyvinyl alcohol.
5.2 parts are mixed into 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. while stirring, and after 2 hours, a capsule liquid containing a diazo compound in the core substance was obtained. (diazo compound) Next, 10 parts of 2-hydroxy-3-naphthoic acid anilide and 10 parts of triphenylguanidine were added to 100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours. A dispersion of was obtained. Furthermore, 20 parts of p-toluenesulfonamide was added to 100 parts of a 4% polyvinyl alcohol aqueous solution and 100 parts of water, and dispersed in a paint shaker for 2 hours to determine the average particle size.
A 3 μm p-toluenesulfonamide dispersion was obtained. A coupling component, 24 parts of a triphenylguanidine dispersion, and 28 parts of a p-toluenesulfonamide dispersion were added to 50 parts of the diazo compound capsule solution obtained as described above to prepare a coating solution. This coating solution was coated on smooth high-quality paper (50 g/m ² ) using a coating bar to give a dry weight of 10 g/m ² and dried at 25° C. for 30 minutes to obtain a heat-sensitive material. Example 2 A thermosensitive recording material was obtained in the same manner as in Example 1, except that N-(o-chlorophenyl)sulfonamide was used instead of p-toluenesulfonamide. Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that N-(p-methoxyphenyl)sulfonamide was used instead of p-toluenesulfonamide. Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that p-toluenesulfonamide in Example 1 was omitted. Comparative Example 2 Example 1 except that stearic acid amide was used instead of p-toluenesulfonamide in Example 1.
A heat-sensitive recording material was obtained in the same manner as above. (Test method) Heat recording was performed on the obtained heat-sensitive recording material using G mode (HIFAX 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. 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 raw storage stability, the background density (fog) of the heat-sensitive recording material and their temperature were measured at 40°C and relative humidity at 90%.
After storing in a dark place under RH conditions for 24 hours and performing a forced deterioration test, fog was measured using a Macbeth reflection densitometer to observe changes in fog. those results first
Shown in the table.

[Table] "Effects of the Invention" As can be seen from Table 1, Examples 1, 2, and 3 in which a diazo compound was encapsulated and further added a sulfonamide compound were compared to Comparative Example 1 in which no sulfonamide compound was added.
It is an excellent heat-sensitive recording material with the same high image density and less increase in fog after the forced deterioration test. Furthermore, it can be seen that the thermal coloring properties are significantly superior compared to Comparative Example 2 in which a commonly used thermofusible substance was added. Further, in Examples 1 to 3, the whiteness of the heat-sensitive recording materials was improved, and the staking properties were also good.

Claims (1)

[Claims] 1. A heat-sensitive recording material in which a recording layer containing at least a diazo compound and a coupling component is coated on a support, which contains either the diazo compound or the coupling component in microcapsules, and further contains an organic sulfonamide compound. A heat-sensitive recording material characterized in that the recording layer contains at least one species.