JP6971787B2 - 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 color. Get a record. In order to develop (print) 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 thermal recording materials have expanded, the demand for high-speed recording has become even higher in order to further improve productivity, and the development of thermal recording materials that can sufficiently cope with high-speed recording is 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 bleaching agent 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 is to provide a heat-sensitive recording material having good color development sensitivity and high stability of a printed portion with respect to heat.

As a result of diligent studies to achieve the above object, the present inventor has obtained a compound represented by the following general formulas (1) and (2) and a mixture of 1,3-diphenylurea as a color developer. When it was used as a heat-sensitive recording material, it was newly found that the color development sensitivity was good and the printed portion was excellent in heat resistance, and the present invention was completed.

［式（１）及び式（２）中、Ａはヘテロ原子を含んでいても良い炭素数１０以下の２価の飽和炭化水素基である。］
（２）前記一般式（１）で表される化合物が下記式（３）であり、前記一般式（２）で表される化合物が下記式（４）である（１）に記載の感熱記録材料、

（３）一般式（１）及び一般式（２）で表される化合物並びに１，３−ジフェニル尿素の混合比が、１０〜９０：５〜５０：５〜８０である（１）又は（２）に記載の感熱記録材料、
（４）（１）乃至（３）のいずれか一つに記載の感熱記録材料を含む感熱記録層、
（５）（１）乃至（４）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、
に関する。 That is, the present invention
(1) A heat-sensitive recording material comprising 1,3-diphenylurea and a compound represented by the following general formula (1) and general formula (2).

[In the formulas (1) and (2), A is a divalent saturated hydrocarbon group having 10 or less carbon atoms which may contain a heteroatom. ]
(2) The thermal recording according to (1), wherein the compound represented by the general formula (1) is the following formula (3), and the compound represented by the general formula (2) is the following formula (4). material,

(3) The mixing ratio of the compounds represented by the general formulas (1) and (2) and 1,3-diphenylurea is 10 to 90: 5 to 50: 5 to 80 (1) or (2). ) The heat-sensitive recording material,
(4) A heat-sensitive recording layer containing the heat-sensitive recording material according to any one of (1) to (3).
(5) The thermal recording paper containing the thermal recording material or the thermal recording layer according to any one of (1) to (4).
Regarding.

The present invention uses the compounds represented by the above general formulas (1) and (2) and 1,3-diphenylurea (hereinafter abbreviated as compound (5)) as a color developer to develop color sensitivity. It is possible to realize a heat-sensitive recording material in which the printed portion exhibits high stability against heat.

The present invention will be described in detail.
The present invention is a heat-sensitive recording material provided with a heat-sensitive recording layer containing a colorless or light-colored leuco dye and a color developer on a support, and the above general formulas (1) and (2) are used as the color developer. ) Is contained together with the compound (5), and if necessary, other color-developing agents and sensitizers shown below, preservative-improving agents, binders, fillers, and other additives are contained. The present invention relates to a heat-sensitive recording material containing the above.

_{A in the general formula (1) and the general formula (2) is a linear or branched C 1 to} C ₁₀ saturated hydrocarbon which may contain a hetero atom such as an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom. It is a hydrogen group.

A as a 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 a 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.

As the A as a saturated hydrocarbon group containing a hetero atom, for example, a linking group represented by the general formula (6) can be mentioned. ^{A 1} and A ² of the general formula (6) represent C _{1 to} C ₉ alkylene groups, respectively, and the total number of carbon atoms of ^{A 1} and A ^{2 is 10 or less.} Further, X represents a hetero atom such as an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom, and an oxygen atom or a nitrogen atom is preferable.

Specific examples of the compound represented by the general formula (1) used in the present invention are given in Table 1 below, but the present invention is not limited thereto.

Specific examples of the compound represented by the general formula (2) used in the present invention are given in Table 2 below, but the present invention is not limited thereto.

The mixing ratios of the compounds represented by the general formulas (1) and (2) and the compounds (5) used in the heat-sensitive recording material of the present invention are 10 to 90 for the general formula (1) and 10 to 90 for the general formula. (2) is preferably 5 to 50, compound (5) is preferably 5 to 80, formula (1) is preferably 10 to 70, formula (2) is 10 to 40, and compound (5) is more preferably 10 to 60. A mixture of these three compounds was analyzed by high performance liquid chromatography (hereinafter abbreviated as HPLC), and the area% of each obtained compound was defined by the following formula (I) as the "mixing ratio". bottom. The area% of each compound is the sum of the area% of the compounds represented by the general formulas (1) and (2) and the area% of the compound (5) as 100, and the area% of each compound is shown as a percentage. Is.
Mixing ratio = [(Area% of compound represented by general formula (1)): (Area% of compound represented by general formula (2)): (Area% of compound (5))] (I)

Next, the compounds represented by the above general formulas (1) and (2) and the compound (5) used in the present invention can be easily produced as a mixture of reaction products by the following reaction steps.

Examples of the production method thereof include phenyl isocyanate (hereinafter abbreviated as compound (1-1)), 1-aminopropan-2-ol (hereinafter abbreviated as compound (1-2)) and aniline (hereinafter abbreviated as compound (1-2)). , Compound (abbreviated as compound (1-3)) is reacted at a predetermined mixing ratio, so that the compound represented by compound number 5 shown in Table 1 (hereinafter abbreviated as compound (3)) is shown in Table 2. It can be easily produced as a mixture of the compound represented by the above compound No. 5 (hereinafter abbreviated as compound (4)) and the compound (5).

The compound (1-1) and compound (1-) used for synthesizing a mixture of the general formula (1), the general formula (2) and the compound (5) preferably used in the present invention in the above-mentioned production step. The amount of each of 2) and compound (1-3) used is usually 1.1 to 1 mol times that of compound (1-2) 1 mol, and 1.5 to 2 times. The molar number is preferable, and the compound (1-3) is usually 0.001 to 0.5 mol times, preferably 0.02 to 0.4 mol times.

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 steps is preferably 0 ° C. to 100 ° C., less by-products are produced, and the reaction is smoothly carried out.

The solvent used in the above-mentioned production step 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 producing the heat-sensitive recording material of the present invention, the color-developing compound is usually 1 to 50% by mass, preferably 5 to 30% by mass, and the compounds and compounds represented by the above general formulas (1) and (2). The mixture of 5) is usually 1 to 70% by mass, preferably 10 to 50% by mass, the sensitizer is usually 1 to 80% by mass, the storage stability improving agent is usually 0 to 30% by mass, and the binder is usually 1 to 1% by mass. 90% by mass, the filler is usually 0 to 80% by mass, and other lubricants, surfactants, antifoaming agents, and ultraviolet absorbers are used in arbitrary proportions, for example, usually 0 to 30% by mass, respectively (% by 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 a pressure-sensitive recording paper or a heat-sensitive recording paper, and is not particularly limited. , Diphenylmethane-based compound, thiazine-based compound, lactam-based compound, fluorene-based compound, and 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-ethylspirodinaphthopyrane, 3,3'-dichlorospiridinaftpyran, 3-benzylspiridinaftpyran, and 3-propylspirobenzopyrane. , 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'-isopropylidenebis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'- Dihydroxydiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 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-hydroxyisophthal. 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-7 methyl-4benzo Triazole, benzotriazole derivatives such as bromo-5 benzotriazole, saccharin, 1-bromosaccharin, 1-nitrosaccharin, 1-aminosacchari Saccharin derivatives such as saccharin, 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-toluenesulfonyl) -N'-(4-trimethylacetophenyl) urea, N- (benzenesulfonyl) -N'-(3-p-toluenesulfonyloxyphenyl) urea , N- (p-tolusolvonyl) -N'-(3-p-toluenesulfonylphenyl) urea, N- (p-toluenesulfonyl) -N'-(3-phenylsulfonyloxyphenyl) urea, tolubutamide, chlorpropa Examples thereof include sulfonylurea derivatives such as mid.

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 sulphonate, 4-methylphenylmethicylene sulphonate, 4-trylmethicylene sulphonate , 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, cesylbiphenyl compound, 1,4-diacetoxybenzene, 1,4-dipropionoxybenzene, 2-phenoxyethyl-N-phenylcarbame , 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-tbutylphenyl) 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 Compounds, Fatty Acid Anilide Compounds, 2,2'-Bis (4-Methenyl) diethyl ether, Bis (4- Methoxyphenyl) ether, adipii 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) methane 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 phenolic 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 diphenyl sulfone cross-linked compounds represented by the following formula (7) 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 / maleylan 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, antioxidant 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 wet), 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, for example, 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%.
For the follow-up of the reaction and the compounds represented by the above general formulas (1) and (2) and the mixture of the compound (5), GL Sciences was prepared by injecting an evaluation sample having a concentration of about 2500 ppm at an injection volume of 0.2 μL. It was calculated by HPLC analysis at a column oven temperature of 40 ° C. and a wavelength of 254 nm using an Inersil ODS-2 (4.6 mmφ × 15 cm, carrier particle size: 5 μm) column. For the mobile phase, eluent A is acetonitrile, eluent B is 0.05 volume% ammonium acetate aqueous solution, and each eluent composition is continuously flown from A: B = 50:50 to 90:10 for 20 minutes at a flow rate of 0. .Varied at 4 ml / min.

[Synthesis Example 1] Synthesis of a mixture of compound (3), compound (4) and compound (5) -1
To 50 parts of toluene, 2.55 parts of 1-amino-2-propanol and 0.093 parts of aniline were added, and the mixture was stirred at 0 ° C. To there, 4.16 parts of phenyl isocyanate diluted with 20 parts of toluene was added dropwise over 30 minutes. After confirming that phenyl isocyanate was completely reacted by HPLC, the reaction solution was heated to 90 ° C., 3.11 part of phenyl isocyanate was added thereto, and the mixture was stirred at the same temperature for 4 hours. After completion of the reaction, the mixture is cooled to room temperature, the reaction solution is filtered, the obtained white solid is washed with 150 parts of toluene, heated and dried, and the mixing ratio calculated by the formula (I) from the HPLC area% is obtained. A mixture of compound (3), compound (4) and compound (5) at 17:64:19 was obtained.

[Synthesis Example 2] Synthesis of a mixture of compound (3), compound (4) and compound (5) -2
To 50 parts of toluene, 2.55 parts of 1-amino-2-propanol and 0.19 parts of aniline were added, and the mixture was stirred at 0 ° C. 4.29 parts of phenyl isocyanate diluted with 20 parts of toluene was added dropwise thereto over 30 minutes. After confirming that phenyl isocyanate was completely reacted by HPLC, the reaction solution was heated to 90 ° C., 3.10 parts of phenyl isocyanate was added thereto, and the mixture was stirred at the same temperature for 4 hours. After completion of the reaction, the mixture is cooled to room temperature, the reaction solution is filtered, the obtained white solid is washed with 150 parts of toluene, heated and dried, and the mixing ratio calculated by the formula (I) from the HPLC area% is obtained. A mixture of compound (3), compound (4) and compound (5) at 15:54:31 was obtained.

[Example 1] Preparation of heat-sensitive recording material A mixture of compound (3), compound (4) and compound (5) obtained in Synthesis Example 1 was mixed with a multi-bead shocker manufactured by Yasui Kikai Co., Ltd. with the following composition. Model: PV1001 (S)) was used to grind and disperse for 1 hour to prepare the solution [A].

[A] Liquid: 15 parts of the mixture of Synthesis Example 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 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

Then, a heat-sensitive recording layer coating solution was prepared by mixing the liquid and the following agents obtained above in the following composition, mass upon drying on a high-quality paper with a basis weight of 50 g / m ² is a 5 g / m ² The heat-sensitive recording material of the present invention was prepared by applying and drying so as to be.
[A] Liquid 33.3 parts [B] Liquid 8.6 parts 67% Calcium carbonate aqueous dispersion 6.7 parts 15% PVA aqueous solution 20 parts 37% Zinc stearate aqueous dispersion 2.7 parts Water 18.2 parts

[Example 2]
The heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the mixture obtained in Synthesis Example 2 was used instead of the mixture obtained in Synthesis Example 1.

[Comparative Example 1]
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that only compound (3) was used instead of the mixture obtained in Synthesis Example 1.

[Comparative Example 2]
A thermal recording material for comparison was obtained in the same manner as in Example 2 except that only compound (4) was used instead of the mixture obtained in Synthesis Example 1.

[Comparative Example 4]
A mixture having the following composition was crushed and dispersed by a laser diffraction / scattering particle size distribution measuring device LA-950 (manufactured by HORIBA, Ltd.) using a sand grinder so that the median particle size was 1 μm, and the [C] liquid was prepared. A heat-sensitive recording material for comparison was obtained in the same manner as in Example 5 except that the composition of the heat-sensitive recording layer coating liquid described in Example 5 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 heat-sensitive recording materials obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were printed with a pulse width of 0.9 msec using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd. The Macbeth reflection density of the color-developing part 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 below. It can be seen that the higher the Macbeth reflection density, the better the color development.

As is clear from Table 3, in Examples 1 and 2 in which the heat-sensitive recording layer contains the compound (3), the compound (4) and the compound (5) of each of the above mixed ratios, only the compound (3) is used. Compared with Comparative Example 1 using only Comparative Example 1 or Compound (4), and Comparative Example 3 using bisphenol S, which is a color developer described in Patent Document 2, the Macbeth reflection density of the printed portion is higher and the color development property is improved. Is excellent.

[Residual rate of print density]
The heat-sensitive recording materials obtained in Examples 1 and 2 and Comparative Examples 2 and 3 were printed with a pulse width of 1.4 msec using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd. This sample was held at 90 ° C. for 1 hour using a blower constant temperature incubator manufactured by Yamato Kagaku Co., Ltd., trade name DKN402. The Macbeth reflection density of the printing unit 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 4 below. The residual rate of print density was calculated according to the following formula (II).
Residual rate (%) = [(Macbeth reflection density of printed part after heat resistance test) / (Macbeth reflection density of printed part before heat resistance test)] (II)

As is clear from Table 4 above, in Examples 1 and 2 in which the compound (3), the compound (4) and the compound (5) were contained in the heat-sensitive recording layer at the above mixing ratio, the print densities before and after the heat resistance test were obtained. Since the residual ratio of the above is large, the printed portion shows extremely high stability against heat as compared with Comparative Examples 1 and 2.

Claims (4)

A heat-sensitive recording material comprising the compound represented by the following general formula (1) and the general formula (2) and 1,3-diphenylurea.

[In the formulas (1) and (2), A is a divalent saturated hydrocarbon group having 10 or less carbon atoms which may contain a heteroatom. ] Claimed that the compound represented by the general formula (1) is a compound represented by the following formula (3), and the compound represented by the general formula (2) is a compound represented by the following formula (4). Item 1. The heat-sensitive recording material according to Item 1.

A heat-sensitive recording layer containing the heat-sensitive recording material according to claim 1 or 2. A thermal recording paper comprising the thermal recording material or thermal recording layer according to any one of claims 1 to 3.