JP6998733B2 - Thermal recording material - Google Patents

Description

The present invention relates to a heat-sensitive recording material having good color development sensitivity and excellent heat resistance.

In a heat-sensitive recording material, generally, a leuco dye and a color developer such as a phenolic compound are separately dispersed in the form of fine particles, and then the two are mixed, and a binder, a sensitizer, a filler, a lubricant, etc. are added to the mixture. The coating liquid obtained by adding the additive is applied to paper, film, synthetic paper, etc., and one or both of the leuco dye and the color developer are melted and contacted by heating to develop a color. Get a record. In order to develop the color of such a heat-sensitive recording material, a thermal printer or the like having a built-in thermal head is used. Compared to other recording methods, this heat-sensitive recording method (1) does not generate noise during recording, (2) does not require development and fixing, (3) is maintenance-free, and (4) the machine is relatively relatively. Due to its low cost, it is widely used in the facsimile field, computer output, printer field such as calculator, recorder field for medical measurement, automatic ticket vending machine field, thermal recording type label field and the like.

In recent years, as the applications of heat-sensitive recording materials have expanded, the demand for high-speed recording has increased further in order to further improve productivity, and the development of heat-sensitive recording materials capable of sufficiently supporting high-speed recording has been strongly desired. In this case, a developer with a low melting point and a small heat of fusion is required, but this property is due to deterioration of the unrecorded (uncolored) part (background) of the heat-sensitive recording material during manufacturing, use, or storage. Therefore, it is strongly desired to improve not only high whiteness but also stability.

In general, a developer having a phenolic hydroxyl group has a high bleaching ability, and among them, a bisphenol-based chromogen has a high color-developing concentration, and therefore, for example, 2,2-bis (4-hydroxyphenylpropane) shown in Patent Document 1. (Bisphenol A) and 4,4'-dihydroxydiphenyl sulfone (bisphenol S) shown in Patent Document 2 have been reported in large numbers. However, these have drawbacks such as deterioration of the skin (covering the skin).

U.S. Pat. No. 3539375 JP-A-57-11088A

The present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a heat-sensitive recording material having good color development sensitivity and high stability of the background against heat.

As a result of diligent studies to achieve the above object, the present inventor used a specific compound represented by the following general formula (1) as a color developer as a heat-sensitive recording material, and found that the color development sensitivity was good. Moreover, the present invention has been completed by newly discovering that the skin has excellent heat resistance.

［式（１）中、Ａはヘテロ原子を含んでいてもよい炭素数１０以下の２価の飽和炭化水素基である。］
（２）下記一般式（２）乃至（４）で表される化合物から選ばれる１種以上を含有することを特徴とする感熱記録材料、

（３）（１）又は（２）に記載の感熱記録材料を含む感熱記録層、
（４）（１）乃至（３）のいずれか一つに記載の感熱記録材料又は感熱記録層を含む感熱記録紙、
（５）下記式（４）で表される化合物、

に関する。 That is, the present invention
(1) A heat-sensitive recording material, which contains a compound represented by the following general formula (1).

[In the formula (1), A is a divalent saturated hydrocarbon group having 10 or less carbon atoms which may contain a hetero atom. ]
(2) A heat-sensitive recording material containing at least one selected from the compounds represented by the following general formulas (2) to (4).

(3) A heat-sensitive recording layer containing the heat-sensitive recording material according to (1) or (2).
(4) The thermal recording material or the thermal recording paper containing the thermal recording layer according to any one of (1) to (3).
(5) The compound represented by the following formula (4),

Regarding.

The present invention can provide a heat-sensitive recording material having good color development sensitivity and high stability to heat by using a specific compound represented by the above general formula (1) as a color developer. can.

The present invention will be described in detail.
The present invention uses a colorless or light-colored color-developing compound and a specific compound represented by the above general formula (1), and if necessary, other color-developing agents, sensitizers, and storage stability shown below. The present invention relates to a heat-sensitive recording material containing an improver, a binder, a filler, and other additives.

A in the general formula (1) is a linear or branched C ₁ to C ₁₀ saturated hydrocarbon group which may contain a hetero atom such as an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom.

The A of the linear saturated hydrocarbon group is an unsubstituted C ₁ to C ₁₀ alkylene group, of which C ₁ to C ₈ alkylene groups are preferable, and C ₁ to C ₄ alkylene groups are particularly preferable. Specific examples thereof include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and the like.

A as the saturated hydrocarbon group of the branched chain is a C ₁ to C ₁₀ alkylene group having a substituent, and examples of the substituent include C ₁ to C ₈ alkyl groups, and specific examples thereof include C 1 to C 8 alkyl groups. Examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group and the like.

Examples of A as a saturated hydrocarbon group containing a hetero atom include a linking group represented by the following general formula (5). A ¹ and A ² of the general formula (5) represent C1 to C9 alkylene groups, respectively, and X represents a hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom, and a phosphorus atom. However, the total of A ¹ and A ² is 10 or less.

Specific examples of the compound in the present invention can be given in Table 1-1 and Table 1-2 below, but the present invention is not limited thereto.

Next, a method for producing the compound used in the present invention will be described.
Among the compounds represented by the general formula (1), for example, compound number 1 (2) shown in Table 1 contains 2 mol of amino alcohol (1-2) with respect to 1 mol of phenyl isocyanate (1-1). It can be easily produced by reacting.

In the above production process, a base can be used to accelerate the reaction if necessary, and specific examples of the base used include organic bases such as triethylamine and pyridine; sodium hydroxide, potassium hydroxide, sodium carbonate, and the like. Examples thereof include inorganic bases such as potassium carbonate.

The reaction temperature in the above-mentioned production step is usually 0 ° C. to 100 ° C., preferably 50 ° C. to 100 ° C., and the formation of by-products is small, and the reaction is smoothly carried out.

The solvent used in the above production process is not particularly limited as long as it does not affect the reaction. For example, amide compounds such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbon compounds such as methylene chloride, chloroform, dichloroethane; aromatics such as benzene, toluene, and xylene. Examples of the hydrocarbon compound are ether compounds such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether; sulfone compounds such as sulfolane; and sulfoxide compounds such as dimethyl sulfoxide, which are mixed. You may use it.

In forming the heat-sensitive recording material in the present invention, the color-developing compound is usually 1 to 50% by mass, preferably 5 to 30% by mass, and the compound represented by the above general formula (1) is usually 1 to 70% by mass. Preferably, 10 to 50% by mass, the sensitizer is usually 1 to 80% by mass, the storage improving agent is usually 0 to 30% by mass, the binder is usually 1 to 90% by mass, and the filler is usually 0 to 80% by mass. , Other lubricants, surfactants, defoaming agents, and ultraviolet absorbers are used in arbitrary proportions, for example, usually 0 to 30% by mass, respectively (mass% is the mass ratio of each component in the heat-sensitive recording material). .. In the heat-sensitive recording material of the present invention, a color developer, a sensitizer or other additives known per se may be used in combination other than the above-mentioned components.

The color-developing compound used in the present invention is not particularly limited as long as it is generally used for pressure-sensitive recording paper or thermal recording paper. Examples of the color-developing compound used include a fluorine-based compound, a triarylmethane-based compound, a spiro-based compound, a diphenylmethane-based compound, a thiazine-based compound, a lactam-based compound, and a fluorene-based compound, and a fluorine-based compound is preferable.

Specific examples of the fluorin-based compound include 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, and 3- (N-methyl-N-cyclohexyl). Amino) -6-Methyl-7-anilinofluorane, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isobutylamino) ) -6-Methyl-7-anilinofluorane, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluorane, 3- (N-ethyl-N) -Hexylamino) -6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propylamino) -6-methyl-7 -Anilinofluorane, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluorane, 3- Diethylamino-6-methyl-7- (p-fluoroanilino) fluorane, 3- [N-ethyl-N- (p-tolyl) amino] -6-methyl-7-anilinofluorane, 3-diethylamino-6 -Methyl-7- (p-toluizino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) Reno) Fluolan, 3-dibutylamino-7- (o-fluoroanilino) fluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-pyrrolidino-6-methyl-7-anilinoflu Oran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methyl Examples include fluorane, 3-diethylamino-7-octylfluorane, 3- [N-ethyl-N- (p-tolyl) amino] -6-methyl-7-phenethylfluorane, and 3-dibutylamino-6. -Methyl-7-anilinofluorane is preferred.

Specific examples of the triarylmethane compound include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL) and 3,3-bis (p-dimethylamino). Phenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindole-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindole-3) -Il) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-3-yl) phthalide, 3,3-bis (1,2-dimethylindole-3-yl) -5-dimethyl Aminophthalide, 3,3-bis (1,2-dimethylindole-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazole-3-yl) -5-dimethylaminophthalide , 3,3- (2-Phenylindole-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrole-2-yl) -6-dimethylaminophthalide Indole etc. can be mentioned.

Specific examples of the spiro compound include 3-methylspirodinaphthopylan, 3-ethylspirodinaphthopylan, 3,3'-dichlorospirininaphthopyran, 3-benzylspirinaftpyran, and 3-propylspirobenzopyran. , 3-Methylnaphtho- (3-methoxybenzo) spiropiran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indrin-2,2'-benzopyran), etc .; Specific examples of diphenylmethane compounds include , For example, N-halophenyl-leucooramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucooramine, etc .; Specific examples of thiazine compounds include, for example. Benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc .; Specific examples of lactam compounds include, for example, Rhodamine B anilinolactam, Rhodamine B-p-chloroanilinolactum, etc .; Specific examples of fluorene-based compounds include, for example, 3. , 6-bis (dimethylamino) fluorenspiro (9,3') -6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenspiro (9,3') -6'-pyrrolidinoftalide , 3-Dimethylamino-6-diethylaminofluorenspiro (9,3') -6'-pyrrolidinophthalide and the like. These color-developing compounds are used alone or in combination.

The color developer used in the present invention is not particularly limited, but may be any one generally used for pressure-sensitive recording papers and heat-sensitive recording papers, for example, α-naphthol, β-naphthol, p-octylphenol, 4 -T-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (also known as bisphenol A or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol, 4,4'-cyclo-hexylidenediphenol, 2,2' -Bis (2,5-dibrom-4-hydroxyphenyl) propane, 4,4'-isopropyridenebis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'- Dihydroxydiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy -4'-Butoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, Phenolic compounds such as 2,4-dihydroxy-2'-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, 5-hydroxyisophthalate Aromatic carboxylic acid derivatives such as ethyl acid, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof, benzotriazoles, 5-methyls. -1H-benzotriazole, 4-methyl-1H-benzotriazole, phenyl-6-benzotriazole, phenyl-5-benzotriazole, chloro-5-benzotriazole, chloro-5-methylbenzotriazole, chloro-5-isopropyl- Benzotriazole derivatives such as 7-methyl-4-benzotriazole and bromo-5-benzotriazole, saccharin, 1-bromosaccharin, 1-nitrosaccharin, 1 -Saccharin derivatives such as aminosaccharin, methanylanilide, N-phenyl-4-aminobenzenesulfonamide, neourylon, N-phenyl-3-nitrobenzenesulfonamide, N- (4-methyl-2-nitrophenyl) benzenesulfonamide, N Sulfonamide derivatives such as-(2-methoxyphenyl) -p-toluenesulfonamide, N- (2- (3-phenylureido) phenyl) benzenesulfonamide, N- (p-toluenesulfonyl) -N'-(3) -N-Butylaminosulfonylphenyl) urea, N- (p-tolusolvonyl) -N'-(4-trimethylacetonyl) urea, N- (benzenesulfonyl) -N'-(3-p-toluenesulfonyloxyphenyl) ) Urea, N- (p-toluenesulfonyl) -N'-(3-p-toluenesulfonylphenyl) urea, N- (p-toluenesulfonyl) -N'-(3-phenylsulfonyloxyphenyl) urea, tolubutamide, Examples thereof include sulfonylurea derivatives such as chlorpropamide.

Specific examples of the sensitizer (heat-soluble compound) used in the present invention include wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, amide wax, polyethylene oxide, stearic acid, and the like. Bechenic acid, stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylol behenic acid amide, methylol stearate amide, methylene bisstearic acid amide, ethylene bisstearic acid amide, stearic acid anilide, linoleic acid. Anilide, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 1,4-diethoxynaphthalene, 2,6-diisopropylnaphthalene, 1,2-diphenoxyetane, 1,4-di Phenoxybutane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1,2-bis (3,4-dimethylphenyl) ethane, 1-phenoxy-2- (4-Chlorophenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane, 1,2-diphenoxymethylbenzene, o-xylylenebis (phenylether), diphenylglycol, p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, terephthalic acid dibenzyl ester, dimethyl phthalate, dibenzyl isophthalate, p-toluenesulfonic acid phenylester, phenylmethicylene sulfonate, 4-methylphenylmethicylene sulfonate, 4-tolylmethicylene sulfonate , Carbonated diphenyl, oxalic acid dibenzyl ester, oxalic acid di (4-chlorobenzyl) ester, oxalic acid di (4-methylbenzyl) ester, p-benzylbiphenyl, 4-methoxybiphenyl, 4-methylphenylbiphenyl ether, p. -Allyloxybiphenyl, 4- (m-methylphenoxymethyl) biphenyl, m-terphenyl, p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide, 4,4'-diallyloxydiphenylsulfone, diphenylsulfone, 4,4'-dimethylbenzophenone, dibenzoylmethane, p-acetotoluidine, cecilbiphenyl compound, 1,4-diacetoxybenzene, 1,4-dipropionoxybenzene, 2-phenoxyethyl-N-phenylcarba Mate, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4'-(2-methylglycidyloxy) diphenylsulfone, 2,2'-methylenebis (4,6) -Di-t-butylphenyl) phosphate, 2,2'-methylenebis (4,6-di-t-butylphenyl) phosphate metal salt, ammonium salt and polyvalent metal salt, p-nitrobenzoic acid metal salt, Metal salt of phthalic acid monobenzyl ester, metal salt of carcinic acid, p-hydroxyacetanilide, p-hydroxybutyranide, p-hydroxynonalinide, 2,2'-methylenebis (4-methyl-6-t-butylphenol) ), 4,4'-Butylidene-bis (3-methyl-6-t-butylphenol), 4,4'-thiobis (2-t-butyl-5-methylphenol), 1,1,3-Tris (2) -Methyl-4-hydroxy-5-t-butylphenyl) butane, bis (3-t-butyl-4-hydroxy-6-methylphenyl) sulfone, bis (3,5-dibromo-4-hydroxyphenyl) sulfone, 4,4'-sulfonylbis (2-t-butyl-5-methylphenol), 4- [α- (hydroxymethyl) benzyloxy] -4-hydroxydiphenylsulfone, palmitic acid amide, ethylenebisamide, o-toluene sulfone Amid, montanic acid wax, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 4,4'-ethylenedioxy-bis benzoic acid dibenzyl ester, p-nitromethyl benzoate, dibenzoyloxymethane, bis [ 2- (4-Methenylphenoxy) ethyl] ether, methoxycarbonyl-N-stearate benzamide, N-benzoylstearate amide, N-ecoic acid amide, behenic acid amide, p-acetotoluidide, p-acetophenetidine, N -Acetoacetyl-p-toluidine, dimethyl terephthalate, p-methylthiophenylbenzyl ether, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, 1, 4-Di (Phenylthio) Butane, N-Stearyl Steeric Acid Amid, N-Stearyl Urea, Acetate Acetate Anilide Compound, Fatty Acid Anilide Compound, 2,2'-Bis (4-methoxyphenyl) diethyl Ether, Bis (4-Methenylphenyl) ) Ether, Ajipi Diphenyl acid, benzenesulfonic acid phenyl ester, 4-acetylacetophenone, benzamide, thioacetanilide acrylic acid amide, diethyl isophthalate, equal mixture of dibenzyl oxalate and di (4-chlorobenzyl) oxalate, di oxalate (4) Equal mixture of -methylbenzyl) and di (4-chlorobenzyl) oxalate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di- t-butylphenol), 4,4'-dimethoxydiphenylsulfone, 2,4'-dimethoxydiphenylsulfone, 1,2-bis (4-methoxyphenylthio) ethane, 1,2-bis (4-methoxyphenoxy) propane, 1,3-Phenoxy-2-propanol, 1,4-diphenylthio-2-butene, 1,4-diphenylthiobutane, 1,4-diphenoxy-2-butene, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, 1,3-dibenzoyloxypropane, 4,4'-ethylenedioxy-2-bisbenzoic acid dibenzyl ester, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4 -Dibenzyloxynaphthalene, 1,4-dimethoxynaphthalene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-propargyloxybiphenyl, p-benzyloxybenzyl alcohol , Di-β-naphthylphenylenediamine, diphenylamine, carbazole, 2,3-di-m-tolylbutane, 4,4'-dimethylbiphenyl, 2,3,5,6-tetramethyl-4'-methyldiphenylmethane, 4- Acetylbiphenyl, triphenylmethane, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, N-octadecyl-carbamoyl-p-methoxycarbonylbenzene, phenyl β-naphthoate, guaiacol carbonate , Di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,1-diphenylpropanol, 1,1-diphenylethanol, N-octadecylcarbamoylbenzene, dibenzyl sulfide, amido AP-1, aluminum stearate, calcium stearate , Zinc stearate, zinc palmitate, zinc behenate, etc.

（式中、ａは０～６の整数である。） Specific examples of the storage stability improving agent used in the present invention include 2,2'-methylenebis (4-methyl-6-t-butylphenol) and 2,2'-methylenebis (4-ethyl-6-t-butylphenol). , 2,2'-Etilidenebis (4,6-di-t-butylphenol), 4,4'-thiobis (2-methyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-butyl) -M-cresol), 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α', α'-bis (4'-hydroxyphenyl) ethyl] benzene, 1,1, 3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-Tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, Tris (2,6- Dimethyl-4-t-butyl-3-hydroxybenzyl) isocyanurate, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3', 5,5'-tetrabromodiphenylsulfone , 4,4'-Dihydroxy-3,3', 5,5'-Tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-) Hindered phenolic compounds such as hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4'-di Glycidyloxydiphenylsulfone, 4-benzyloxy-4'-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin and other epoxy compounds, N , N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-di-t-butylphenyl) sodium or polyvalent metal salt of phosphate, bis (4-ethyleneiminocarbonylamino Phenol) Methyl and the like can be mentioned. For example, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-ethylidenebis (4,6-di). -T-butylphenol), 4,4'-thiobis (2-methyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-butyl-m-cresol), 1- [α-methyl-α) -(4'-Hydroxyphenyl) ethyl] -4- [α', α'-bis (4'-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-4-hydroxy-5- Cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, tris (2,6-dimethyl-4-t-butyl-3-hydroxybenzyl) isocia Nurate, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3', 5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3', 5 , 5'-Tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2- Hindered phenol compounds such as bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4'-( 2-Methylglycidyloxy) Diphenyl sulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin and other epoxy compounds, N, N'-di-2-naphthyl-p-phenylenediamine , 2,2'-Methylenebis (4,6-di-t-butylphenyl) phosphate sodium or polyvalent metal salt, bis (4-ethyleneiminocarbonylaminophenyl) methane, urea urethane compound (Chemiplo Kasei Co., Ltd.) Coloring agents UU and the like), and diphenylsulfone cross-linked compounds represented by the following formula (6) or mixtures thereof and the like can be mentioned.

(In the formula, a is an integer from 0 to 6.)

Specific examples of the binder used in the present invention include methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group modified polyvinyl alcohol, sulfonic acid group modified polyvinyl alcohol, and silyl. Basically modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, water-soluble isoprene rubber, alkali salts of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleyl anhydride. Water-soluble ones such as alkali salts of acid copolymers or (meth) acrylic acid ester copolymers, styrene / (meth) acrylic acid ester copolymers, polyurethanes, polyester-based polyurethanes, polyether-based polyurethanes, polyacetic acid Vinyl, ethylene / vinyl acetate copolymer, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinylidene chloride, polystyrene, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer , Styrene / butadiene / acrylic acid-based copolymer, acrylonitrile / butadiene (NB) copolymer, carboxylated acrylonitrile / butadiene (NB) copolymer, hydrophobicity of composite particles of colloidal silica and (meth) acrylic resin, etc. Examples include polymer emulsions.

Specific examples of the filler used in the present invention include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, and polystyrene resin. Examples include urea-formalin resin.

Further, in the present invention, various additives other than the above can be used, for example, higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head wear and sticking, and antioxidation or antiaging. Examples thereof include a phenol derivative for imparting an effect, an ultraviolet absorber such as a benzophenone compound and a benzotriazole compound, various surfactants, and an antifoaming agent.

Next, a method for preparing the heat-sensitive recording material of the present invention will be described. The color developer and sensitizer used in the present invention are separately pulverized and dispersed in a disperser such as a ball mill, an attritor, and a sand mill together with a binder or other additives as necessary to form a dispersion liquid. After that (usually, water is used as a medium when pulverizing or dispersing in a wet manner), the dispersion liquid is mixed to prepare a heat-sensitive recording layer coating liquid, and paper (plain paper, woodfree paper, coated paper, etc.) can be used. ), A support such as a plastic sheet or synthetic paper, which is usually coated with a bar coater, a blade coater or the like so as to have a dry mass of 1 to 20 g / m ² , and dried to produce the heat-sensitive recording material of the present invention.

Further, if necessary, an intermediate layer may be provided between the heat-sensitive recording layer and the support, or an overcoat layer (protective layer) may be provided on the heat-sensitive recording layer. The intermediate layer and the overcoat layer (protective layer) are pulverized and dispersed as necessary in the same manner as in the preparation of the heat-sensitive recording layer coating liquid, together with the above-mentioned binder or other additives if necessary, and are intermediate. It is provided by preparing a coating liquid for a layer or a coating liquid for an overcoat layer (protective layer), applying the coating liquid so that the mass at the time of drying is usually about 0.1 to 10 g / m ² , and drying.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In the examples, "part" is a mass part and "%" is a mass%.

[Example 1] Synthesis of compound number 1 (formula (2)) shown in Table 1-1 3.66 parts of ethanolamine was added to 60 parts of toluene and heated to 70 ° C. When 14.3 parts of phenyl isocyanate diluted with 20 parts of toluene was added dropwise thereto over 30 minutes, the solid content was precipitated and the mixture was stirred as it was at the same temperature for 1 hour. After completion of the reaction, the mixture is cooled to room temperature, the reaction solution is filtered, the obtained white solid is washed with 50 parts of toluene and 50 parts of water, and heated and dried to be represented by Compound No. 1 shown in Table 1-1. 15.4 parts of the compound to be used was obtained.
MS (ESI): [M + H] ⁺ : cal. : 300.1, found: 300.1

[Example 2] Synthesis of compound number 5 (formula (3)) shown in Table 1-1 To 90 parts of toluene was added 3.27 parts of 1-amino-2-propanol and heated to 70 ° C. When 10.4 parts of phenyl isocyanate diluted with 20 parts of toluene was added dropwise thereto over 30 minutes, the solid content was precipitated and the mixture was stirred as it was at the same temperature for 1 hour. After completion of the reaction, the mixture is cooled to room temperature, the reaction solution is filtered, the obtained solid is washed with 50 parts of toluene and 50 parts of water, and heated and dried to be represented by the compound number 5 shown in Table 1-1. 11.5 parts of the compound was obtained.
MS (ESI): [M + H] ⁺ : cal. : 314.1, found: 314.1

[Example 3] Synthesis of compound number 9 (formula (4)) shown in Table 1-1 8.8 parts of 2- (2-aminoethoxy) ethanol was added to 70 parts of toluene and heated to 70 ° C. 20 parts of phenyl isocyanate diluted with 20 parts of toluene was added dropwise thereto over 30 minutes. The reaction solution was filtered, the obtained solid was washed with 50 parts of toluene and 50 parts of water, and dried as shown in Table 1-1 to obtain 25 parts of the compound represented by Compound No. 9.
MS (ESI): [M + H] ⁺ : cal. : 344.2, found: 344.2

[Example 4] Preparation of heat-sensitive recording material The compound (formula (2)) represented by compound number 1 shown in Table 1-1 obtained in Example 1 was prepared by Yasui Kikai Co., Ltd. with the following composition. The solution [A] was prepared by pulverizing and dispersing for 1 hour using a multi-bead shocker (model: PV1001 (S)) manufactured by the same company.

[A] Liquid: Compound No. 1 15 parts in Table 1-1
20 parts of 25% PVA aqueous solution
65 parts of water

A mixture having the following composition is crushed and dispersed by a laser diffraction / scattering type particle size distribution measuring device LA-950 (manufactured by HORIBA, Ltd.) to a median particle size of 1 μm using a sand grinder to disperse the color-developing compound. Liquid [B] was prepared.
[B] Liquid: 3-dibutylamino-6-methyl-7-anilinofluorane 35 parts
40 parts of 15% PVA aqueous solution
25 copies of water

Next, each liquid obtained above and the following chemicals were mixed with the following composition to prepare a thermal recording layer coating liquid, and the mass at the time of drying was 5 g / m ^{2 on high-quality paper having a basis weight of 50 g / m 2 .} The heat-sensitive recording material of the present invention was prepared by applying and drying so as to be.
[A] Liquid 40.0 parts [B] Liquid 8.6 parts 67% Calcium carbonate water dispersion 9.0 parts 48% modified styrene-butadiene copolymer latex 6.3 parts Water 36.1 parts

(Formation of protective layer)
Next, a protective layer coating liquid having the following composition was applied onto the heat-sensitive recording layer so that the mass at the time of drying was 2 g / m ² , and dried to prepare a heat-sensitive recording material with a protective layer.
40% styrene / acrylic acid ester copolymer emulsion 115 parts 5% bentonite water dispersion 17 parts 45% styrene / acrylic copolymer aqueous emulsion 44 parts 39% zinc stearate aqueous dispersion 103 parts 67% calcium carbonate aqueous dispersion 15 copies

[Example 5]
Example 4 except that the compound represented by compound number 5 in Table 1-1 (formula (3)) was used instead of the compound represented by compound number 1 in Table 1-1 (formula (2)). The heat-sensitive recording material of the present invention was obtained in the same manner as above.

[Example 6]
Example 4 except that the compound represented by compound number 9 in Table 1-1 (formula (4)) was used instead of the compound represented by compound number 1 in Table 1-1 (formula (2)). The heat-sensitive recording material of the present invention was obtained in the same manner as above.

[Comparative Example 1]
A mixture having the following composition is crushed and dispersed by a laser diffraction / scattering type particle size distribution measuring device LA-950 (manufactured by HORIBA, Ltd.) using a sand grinder so that the median particle size becomes 1 μm, and the [C] solution is prepared. A heat-sensitive recording material for comparison was obtained in the same manner as in Example 4 except that the composition of the heat-sensitive recording layer coating liquid described in Example 4 was changed from the liquid [A] to the liquid [C]. ..
[C] Liquid: 25 parts of bisphenol S
20 parts of 25% PVA aqueous solution
55 parts of water

[Color development test]
The color-developing portion of each of the heat-sensitive recording materials obtained in Examples 4 to 6 and Comparative Example 1 printed with a pulse width of 1.0 msec using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd. The Macbeth reflection density was measured using a colorimeter manufactured by X-Rite, trade name "eXact". The colors were measured under the conditions of Illuminant C as the light source, ANSI A as the density standard, and a viewing angle of 2 degrees. The results are shown in Table 2 below. It can be seen that the higher the Macbeth reflection density, the better the color development.

As is clear from Table 2, Examples 4 to 6 in which the compound represented by the general formula (1) is used as a color developer are comparative examples in which bisphenol S, which is a color developer described in Patent Document 2, is used. Compared to No. 1, the Macbeth reflection density of the color-developing portion is high, and the color-developing property is excellent.

[Heat resistance of the skin]
The heat-sensitive recording materials obtained in Examples 4 to 6 and Comparative Example 1 were held at 90 ° C. for 1 hour using a blower constant temperature incubator manufactured by Yamato Kagaku Co., Ltd., trade name DKN402. The ISO whiteness of the background before and after the test was measured using a colorimeter manufactured by X-Rite, trade name "eXact". The colors were measured under the conditions of Illuminant C as the light source, ANSI A as the density standard, and a viewing angle of 2 degrees. The results are shown in Table 3. It can be seen that the smaller the amount of change in ISO whiteness before and after the test, the better the heat resistance of the skin.

As is clear from Table 3 above, in Examples 4 to 6 in which the compound represented by the formula (1) was used as a color developer, the amount of change in ISO whiteness before and after the heat resistance test was small, and therefore, Patent Documents Compared with Comparative Example 1 using bisphenol S, which is the color developer described in 2, the skin shows extremely high stability against heat.

Claims (4)

A heat-sensitive recording material containing at least one selected from the compounds represented by the following general formulas (2) to (4) .

A heat-sensitive recording layer containing the heat-sensitive recording material according to claim 1 . A thermal recording paper comprising the thermal recording material or thermal recording layer according to claim 1 or 2 . A compound represented by the following formula (4).