JPH0437795B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Application of the Invention) 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. (Technical Background of the Invention) The thermal recording method does not require (1) phenomena. (2) When the support is paper, the paper quality is similar to ordinary paper; (3) it is easy to handle. (4) High color density. (5) The recording device is simple and inexpensive. (6) Due to its advantages such as no noise during recording, it has become rapidly popular in the field of facsimile machines and printers in recent years. As the heat-sensitive recording material, a leuco color-forming heat-sensitive recording material, which is excellent in color density and color development speed, is mainly used. However, leuco color-forming heat-sensitive recording materials have the disadvantage that they develop color when handled or heated after recording, or when solvents are attached to them, staining the recorded image, and they also have the disadvantage that the color is erased by the plasticizer in the cellophane tape. I have it. In order to prevent color development due to careless handling, granular wax is added (Japanese Patent Publication No. 14531/1983), or a coating layer is provided to prevent penetration of plasticizer (Utility Model Publication No. 14531/1983). 125354) etc. are known.
However, this method is still not completely satisfactory and has not been used particularly for the purpose of preventing falsification after recording, and improvements have been strongly desired. As a method to stop color development in unnecessary areas after thermal recording, JP-A-Sho
No. 57-123086, JP-A No. 57-125092, etc., using a heat-sensitive recording material consisting of a diazo compound, a coupling component, and an alkali generator or a coloring aid, is used for thermal recording after light irradiation. A method is known in which color development is stopped by decomposing the diazo compound in the reaction. However, this recording material also undergoes gradual pre-coupling during storage, and undesirable (fogging) may occur. For this purpose, one of the coloring components is present in the form of discontinuous particles (solid dispersion) to prevent contact between the components.
Although measures are being taken to prevent pre-coupling, the storage stability of recording materials (hereinafter referred to as storage stability)
However, it still has the disadvantage that it is not sufficient and the thermal color development is reduced. As another measure, it is known to separate the diazo compound and the coupler component in separate layers to minimize contact between the components. 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 thermal color development, either the coupling component or the basic substance is replaced with a non-polar wax-like substance (Japanese Patent Application Laid-Open No. 57-4414, JP-A No. 57-142636).
It is also known to isolate it from other components by encapsulating it with a hydrophobic polymer substance (Japanese Patent Application Laid-open No. 192944/1983). 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 typical capsule. 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, we
58-65043, in which a core substance contains at least one component involved in a color reaction, and a wall is formed around the core substance by polymerization to form a microcapsule. We have discovered a heat-sensitive recording material. However, even in this method, a heat-sensitive recording material with even higher thermochromic properties has 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 raw storage stability and high thermochromic properties. A second object of the present invention is to provide a heat-sensitive recording material that can stop color development in unnecessary areas by photodegrading unreacted diazo compounds after heat recording (hereinafter referred to as fixing). . A third object of the present invention is to provide a heat-sensitive recording material with excellent manufacturing suitability. (Structure of the Invention) As a result of intensive research, the present inventors have discovered a heat-sensitive recording material in which a recording layer containing a diazo compound, a coupling component, and a basic substance or a substance that becomes basic by heat is provided on a support. The diazo compound is contained in microcapsules, and the microcapsules contain a compound represented by (), (), (), () or () below that lowers the glass transition point of the wall material of the microcapsules. This was achieved using heat-sensitive recording materials. In the above formula, R ₁ represents hydrogen or an alkyl group, an aralkyl group, or an aryl group, and R ₂ , R ₃ , R ₄ , R ₅ and R ₆ represent an alkyl group or an aralkyl group. The heat-sensitive recording material of the present invention can stop the color-forming property of the diazo compound by photodecomposing the unreacted diazo compound after it is thermally colored. It is also possible to first imagewise expose and then uniformly heat the unexposed portions to thermally color them. The microcapsules of the present invention are destroyed by heat or pressure, as used in conventional recording materials, to bring the reactive substance contained in the core of the microcapsule into contact with the reactive substance outside the microcapsule. Rather than causing a coloring reaction, the reactive substance present in the core and outside of the microcapsule is heated to permeate the microcapsule wall and cause a reaction. When used in combination with the microcapsules used in the present invention, the compound that lowers the glass transition point of the wall material of the microcapsules used in the present invention (hereinafter referred to as a transition point adjusting agent) is a commonly used thermoplastic material. Thermal coloring properties can be significantly improved compared to the above. The glass transition point of the present invention is Viblon DDV-
Using a mold (manufactured by Toyo Baldwin Co., Ltd.), the peak humidity of tan δ obtained from the following formula was taken as the glass transition point. (For the measurement of glass transition point, please refer to "Mechanical Properties of Polymers")
(LE Hielsen, “Mechanical property of
Marcel Dekker Inc., New York
(published in 1975)). ) tan δ=dynamic loss modulus/dynamic storage modulus The transition point adjusting agent of the present invention is preferably one that lowers the glass transition point of the wall material of the microcapsules to 80 to 150°C. More preferably, the temperature is lowered to 100 to 130°C. Specific examples of the transition point adjusting agent of the present invention include the following. p-t-butylphenol, p-t-octylphenol, p-α-cumylphenol, p-t
-pentylphenol, m-xylenol, 2,
5-dimethylphenol, 3-methyl-4-isopropylphenol, p-benzylphenol,
o-cyclohexylphenol, p-(diphenylmethyl)phenol, p-(α,α-diphenylethyl)phenol, o-phenylphenol, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, Benzyl p-hydroxybenzoate, p-
Methoxyphenol, p-butoxyphenol,
p-heptyloxyphenol, p-benzyloxyphenol, p-dimethoxybenzene, p-
Examples include benzyloxymethoxybenzene. One or more of these compounds can be selected and used depending on the wall material of the microcapsule. Furthermore, 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, so if such compounds are selected,
It is effective because the coloring temperature is further lowered. Particularly preferred transition point regulators are p-benzyloxyphenol, pt-butylphenol, p-xylylene diol, and 2,6-dimethylphenol. The transition point regulator of the present invention is used in an amount of 0.1 to 10 parts by weight per 1 part by weight of the basic substance. More preferably, it is in the range of 0.5 to 5 parts by weight. or,
The transition point adjusting agent is not particularly limited in the production of heat-sensitive recording materials, but it is preferable to use it after adjusting it to be the same as the basic substance. The diazo compound used in the present invention has the general formula
It is a diazonium salt represented by ArN ₂ +X ^- , and it is a compound that can develop a color by causing a coupling reaction with a coupling component, and can be decomposed by light. (In the formula, Ar represents an aromatic moiety, N ₂ + ⁺ represents a diazonium group,
X ^- represents an acid anion. ) The aromatic moiety is represented by the following general formula. In the formula, Y represents a substituted amino group, alkoxy group, arylthio group, alkylthio group, or acylamino group, and R represents an alkyl group, alkoxy group, arylamino group, or halogen (I, Br, Cl, F)
represents. Preferred examples of the substituted amino group for Y include a monoalkylamino group, dialkylamino group, arylamino group, morpholino 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, 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 2 to
(ClF _2l+1 SO ₂ ) ₂ CH ^- (l is an integer from 1 to 18),

[Formula] (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, among the acid anions, those containing a perfluoroalkyl group or perfluoroalkenyl group, or PF ₆ ^- are preferable because they cause 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 a diazo compound (diazonium salt) in a basic atmosphere.
Specific examples include resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, and 1,5-dihydroxynaphthalene. , 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-
naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-2'-methylanilide, 2-hydroxy-
3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyl-oxy-
Propylamide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetanilide, 1
-Phenyl-3-methyl-5-pyrazolone, 1-
(2',4',6'-trichlorophenyl)-3-benzamido-5-pyrazolone, 1-(2',4',6'-trichlorophenyl)-3-anilino-5-pyrazolone, 1- Phenyl-3-phenylacetamide-
Examples include 5-pyrazolone and the like. Furthermore, by using two or more of these coupling components in combination, an image of any color tone can be obtained. As the basic substance of the present invention, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali upon heating is used. Basic substances include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, and triazoles. Examples include nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines, and pyridines. Specific examples of these are:
For example, ammonium acetate, tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allyl urea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenylimidazole, 2-phenyl-4 -Methyl-imidazole, 2-undecyl-imidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2
-imidazoline, 2-phenyl-2-imidazoline, 1,2,3-triphenylguanidine, 1,
2-ditolylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetate,
N,N'-dibenzylpiperazine, 4,4'-dithiomorpholine, morpholinium trichloroacetic acid hydrochloride,
These include 2-amino-benzothiazole and 2-benzoylhydrazino-benzothiazole. Two or more of these basic substances can also be used in combination. In the present invention, the diazo compound contained in the core material of the microcapsule is dissolved in a water-insoluble organic solvent, and after emulsification, a microcapsule wall is formed around it by polymerization, which improves the shelf life. It is effective in increasing the color development speed and color density. The organic solvent preferably has a boiling point of 180°C or higher, such as phosphoric acid ester, phthalic acid ester, other carboxylic acid ester, fatty acid amide, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane, etc. used. Specific examples include tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, and dioctyl sebacate. , dibutyl sebacate, dioctyl adipate, trioctyl trimellistate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1'-ditolylethane, 2, 4-Jitter
Syaryaminophenol, N,N-dibutyl-2
-butoxy-5-tertiaryoctylanili and the like. Among these, ester solvents such as dibutyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are preferred. The organic solvent is used as a core material in the emulsified droplets (consisting of diazo compounds, organic solvents, capsule wall forming substances, etc.).
It is preferable to contain up to 70% by weight. More preferably, it is 20 to 55% by weight. The microcapsules of the present invention are produced by emulsifying a core material containing a diazo compound and then forming a wall of a polymeric material around the oil droplets. A reactant forming a polymeric substance is added to the interior of the oil droplet and/or to the exterior of the oil droplet. Specific examples of polymeric substances include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, etc. can be mentioned. Two or more types of polymeric substances can also be used in combination.
Preferred polymeric materials are polyurethane, polyurea, polyamide, polyester, polycarbonate, and more preferred are polyurethane and polyurea. Among the diazo compounds, coupling components, and basic substances that are the main components used in the present invention, in addition to diazo compounds, diazo compounds and coupling components, diazo compounds and basic substances, or diazo compounds and couplings can be used as core materials for microcapsules. Components and basic substances can be used. 2
If seeds are used as core materials, they can be contained in the same microcapsule or in separate microcapsules. When three types are used as core substances, it is not possible to contain the three types in the same microcapsule, but there are various combinations. Other ingredients not used as the core material of the microcapsules are used in the heat-sensitive layer outside the microcapsules. 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 (such as 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. By rising, 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. 3468922, No. 3773695, No. 3793268, Tokko Akira
No. 48-40347, No. 49-24159, JP-A No. 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. Furthermore, by combining polyvalent isocyanate, which is the first wall-forming substance, and polyol, which is the second wall-forming substance, the thermal permeability of the reactive substance can be changed arbitrarily. Examples of the polyvalent isocyanate that is the first wall-forming substance in the present invention 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'-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, tetraisocyanates such as 4,4′-dimethyldiphenylmethane-2,2′,5,5-tetraisocyanate, Isocyanate preforms such as adducts of hexamethylene diisocyanate and trimethylolpropane, adducts of 2,4-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 in the present invention include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, and hydroxy polyalkylene ethers. Preferred polyols include two Examples include polyhydroxy compounds with a molecular weight of 5000 or less that have the following groups (), (), (), or () in the molecular structure between the hydroxyl groups. ()Aliphatic hydrocarbon group having 2 to 8 carbon atoms Here, Ar in (), (), () represents a substituted or unsubstituted aromatic moiety, and the aliphatic hydrocarbon group in () has -CnH _2o - as its basic skeleton,
A hydrogen group may be substituted with an element. 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 hydrogen groups of 0.02 to 2 moles per mole of isocyanate groups. Water-soluble polymers can be used when making microcapsules, but water-soluble polymers include water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. Can be used both natural and synthetic
For example, those having -COO ^- , -SO ₃ groups, etc. can be mentioned. Specifically, anionic natural polymers include gum arabic and 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 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. When making microcapsules, they can be made from an emulsion containing 0.2 wt% or more of the diazo compound to be microencapsulated. Whether the coupling component or basic substance used in the present invention is contained inside the microcapsule or in the photosensitive layer outside the microcapsule, the coupling component is 0.1 to 1 part by weight of the diazo compound. 10 parts by weight, basic substance is
It is preferable to use it in a proportion of 0.1 to 20 parts by weight. Moreover, it is preferable to apply the diazo compound at 0.05 to 2.0 g/m ² . When the coupling component, basic substance, and transition point regulator used in the present invention are not microencapsulated, they are preferably used after being dispersed in solid form 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 coupling component, the basic substance, and the transition point regulator are each added in an amount of 5 to 40 wt% 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/m ² . Specific examples of heat-melting substances include fatty acid amides, N-substituted fatty acid amides, ketone compounds, urea compounds, esters, and the like. The heat-sensitive recording material of the present invention can be coated with a suitable binder. As a binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose,
Hydroxypropyl cellulose, gum arabic,
Various emulsions such as gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic ester, and ethylene-vinyl acetate copolymer can be used. The amount used is 0.5 to 5 g/m ² of solid content. In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, and pyrophosphoric acid can be added as acid stabilizers. The heat-sensitive recording material of the present invention comprises a coupling component,
The basic substance, the main component of the transition point adjuster, and other additives are added as the core material of microcapsules, or they are solidly dispersed, or dissolved as an aqueous solution and then mixed to make a coating solution, which can be used for paper or synthetic materials. It is coated onto a support such as a 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 form a solid content of 2.5 to 25.
A heat-sensitive layer of g/m ² is provided. Another method is to add the coupling component, the basic substance, the main component of the transition point regulator, 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 them. Prepare a coating solution, apply it on the support, dry it, and reduce the solid content to 2.
A precoat layer of ~10 g/m ² is provided, and the main component diazo compound and other additives are added as a core material of microcapsules, or they are dispersed as a solid or dissolved as an aqueous solution and then mixed. It is also possible to form a laminated type by applying a coating solution prepared by the method and drying it to form 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 an alkyl ketene dimer (described in JP-A-55-14281) is recommended in terms of storage stability over time. It's 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 size degree/(meter basis weight) ² described in JP-A-57-116687 is used. ≧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-57-20047, JP-A-58-20047
Paper with a density of 0.9 g/cm ³ or less and an optical contact ratio of 15% or more as described in 69091, beaten to 400 c.c. or more at the Canadian standard water level (JIS P8121) described in JP-A-58-69097. Paper made from pulses to prevent coating liquid from seeping in, improved color density and resolution by using the glossy side of base paper made by Yankee machine as the coating surface, described in JP-A-58-65695, JP-A-58-65695. The paper described in 145872/1982, 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 gives 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 thermal phenomenon type 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 1 Two parts of the following diazo compound and 18 parts of an adduct of xylylene diisocyanate and trimethylolpropane (3:1) were added and dissolved in a mixed solvent of 24 parts of dibutyl phthalate and ethyl acetate. This diazo compound solution was mixed with an aqueous solution containing 3.5 parts of polyvinyl alcohol, 1.7 parts of gelatin, and 58 parts of water, and emulsified and dispersed at 20°C to obtain an emulsion with an average particle size of 3 μm. 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, 2hydroxy-3-naphthoic acid anilide 20
100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed with a sand mill for about 24 hours to determine the average particle size.
A 3μ coupling component dispersion was obtained. Next, 20 parts of triphenylguanidine was added to 100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours to obtain a dispersion of triphenylguanidine with an average particle size of 3 μm. Furthermore, 20 parts of pt-butylphenol was added to 100 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours to obtain a dispersion of pt-butylphenol having an average particle size of 3 .mu.m. To 50 parts of the capsule liquid of the diazo compound obtained as above, 15 parts of a dispersion of a coupling component and 15 parts of a dispersion of triphenylguanidine, p-t-
A coating solution was prepared by adding 30 parts of a dispersion of butylphenol. Apply this coating solution to smooth high-quality paper (50 g/m ² ) using a coating rod to give a dry weight of 20 g/m ^{2 .}
It was coated with a bar so as to have the following properties and dried at 45°C for 30 minutes to obtain a heat-sensitive recording material. The image density and color development start temperature of the obtained heat-sensitive recording material were measured by the following test methods. The results are shown in Table 1. Separately, 20 parts of an adduct of xylylene diisocyanate and trimethylol pane (3:1) was dissolved in 30 parts of ethyl acetate, coated on a polyethylene sheet with a bar, reacted in water at 40 to 60°C, peeled off, and then peeled off at 24°C. ,
A film with a thickness of 10 to 20 μm was obtained by air drying at 64% RH for 1 day. This membrane was mixed with 20% pt-butylphenol.
After immersion in methanol solution for 30 hours, 24℃, 64%
It was air-dried at RH for one day to obtain a sample of the glass transition point adjusting agent for capsule wall material. The glass transition point of the obtained sample film was measured by the following test method. The results are shown in Table 1. Meanwhile, the melting point of a 1:1 mixture of triphenylguanidine and pt-butylphenol was investigated and the results are shown in Table 1. (Test method) (1) Measurement of image density and color development start temperature G mode (high fax
700) (manufactured by Hitachi, Ltd.), and then the entire surface was exposed and fixed using Ricopy Super Dry 100 (manufactured by Ricoh, Ltd.). The image density, which is the blue density, of the obtained recorded image was measured using a Macbeth reflection densitometer. In addition, heat-sensitive recording materials are heated in the temperature range of 60 to 150℃,
It was heated with a heat stamp at 300 g/cm ² and the temperature at which color development started was examined. (2) Measurement of glass transition point Vibron DDV-type (Toyo Baldwin
Co., Ltd.) to measure the dynamic storage modulus (E') and dynamic loss modulus (E'') of the sample membrane, tanδ=
E″/E′ was calculated and the temperature at which the peak tanδ was obtained was taken as the glass transition point. The heating rate at this time was 2°C/min. (3) Measurement of melting point The mixture was measured using a scanning differential calorimeter DSC- (manufactured by PerkinElmer Co., Ltd.) at a heating rate of 10°C/min.
Measured by. The results are shown in Table 1. Examples 2 to 6 Instead of p-t-butylphenol in Example 1, p-benzyloxyphenol, p-xylylene diol, benzyl p-oxybenzoate,
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 2,6-dimethylphenol or 1,4-dimethoxybenzene was used. The color development start temperature and image density of the five types of heat-sensitive recording materials obtained were measured in the same manner as in Example 1. Next, a sample for measuring the glass transition point of the capsule wall material was prepared in the same manner as in Example 1 using the above transition point adjusting agent instead of pt-butylphenol. The transition point was measured. Furthermore, the melting point of a 1:1 mixture of triphenylguanidine and the above transition point regulator was measured in the same manner as in Example 1. The above results are shown in Table 1. Comparative Example 1 Samples for measuring the glass transition point of heat-sensitive recording materials and capsule wall materials were prepared in the same manner as in Example 1, except that pt-butylphenol in Example 1 was removed, and in the same manner as in Example 1. It was tested. on the other hand,
The melting point was determined by measuring the melting point of pt-butylphenol alone. The results obtained are shown in Table 1. Comparative Example 2 A thermosensitive recording material and a capsule wall material were prepared in the same manner as in Example 1 except that 2,4-di-t-butyl-5-methylphenol was used instead of pt-butylphenol in Example 1. A sample for glass transition point measurement was prepared and tested in the same manner as in Example 1. Also, triphenylguanidine and 2,4-di-
The melting point was determined on a 1:1 mixture with t-butyl-5-methylphenol. The results obtained are shown in Table 1.

[Table] As can be seen from Table 1, in the case of Examples 1, 2, 3, 4, 5, and 6, in which compounds that have the effect of significantly lowering the glass transition point of the capsule wall material were added, Compared to Comparative Example 1, in which no compound was added, or Comparative Example 2, in which a compound that did not have the effect of lowering the glass transition point of the capsule wall material (although it had the effect of lowering the melting point of triphenylguanidine) was added, the coloring temperature was It is an excellent heat-sensitive recording material, with a low image density and an equally high image density.

Claims (1)

[Scope of Claims] 1. In a heat-sensitive recording material in which a recording layer containing a diazo compound, a coupling component, and a basic substance or a substance that becomes basic by heat is provided on a support, the diazo compound is microencapsulated. A heat-sensitive recording material characterized by containing a compound represented by (), (), (), () or () below, which is contained in the microcapsule wall material and lowers the glass transition point of the wall material of the microcapsule. . In the above formula, R ₁ is hydrogen, an alkyl group, an aralkyl group, an aryl group, R ₂ , R ₃ , R ₄ , R ₅ and R ₆
represents an alkyl group or an aralkyl group.