Thermal recording materials

Abstract

(In formula (1), R1 to R10 each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryl oxy group, an alkyl carbonyl oxy group, an aryl carbonyl oxy group, an alkyl carbonyl amino group, an aryl carbonyl amino group, an alkyl sulfonyl amino group, an aryl sulfonyl amino group, a monoalkyl amino group, a dialkyl amino group, or an aryl amino group.)

Description

[Technical field]

[0001] The present invention relates to a heat-sensitive recording material which utilizes color development caused by the reaction between a color-forming dye and a color developer. [Background technology]

[0002] In general, a thermal recording material is prepared by dispersing a leuco dye and a color developer such as a phenolic compound separately into fine particles, mixing the two, adding additives such as binders, sensitizers, fillers, and lubricants, and coating the resulting liquid on paper, film, synthetic paper, etc., and by heating, one or both of the leuco dye and the color developer melt and come into contact with each other, causing a chemical reaction to occur, resulting in a colored record. To develop the color of such a thermal recording material, a thermal printer with a built-in thermal head is used. Compared to other recording methods, this thermal recording method has the following features: (1) no noise is generated during recording, (2) no development or fixing is required, (3) maintenance is free, and (4) the machine is relatively inexpensive. Therefore, it is widely used in facsimiles, computer output, printers for calculators, medical measurement recorders, automatic ticket vending machines, thermal recording labels, etc.

[0003] In recent years, as the range of uses of thermal recording materials has expanded, the demand for high-speed recording has increased, and there has been a strong demand for the development of thermal recording materials that are excellent in thermal response and can fully accommodate high-speed recording. In order to meet such demands, research and development has been carried out on color-forming dyes, color developers, storage stabilizers, etc., but a material that satisfies the balance between color sensitivity, image storage stability, etc. has not yet been found.

[0004] Generally, color-developing compounds having a phenolic hydroxyl group have high color-developing ability, and among them, many reports have been published on bisphenol-based compounds due to their high color-developing density, and 2,2-bis(4-hydroxyphenylpropane) (bisphenol A) (Patent Document 1) and 4,4'-dihydroxydiphenyl sulfone (bisphenol S) (Patent Document 2) have been proposed. However, these compounds have a high melting point, leading to poor thermal response, and also to the drawback of poor water resistance of the printed area and poor heat resistance of the background.

[0005] In response to this, a heat-sensitive recording material using a specific color-developing compound has been disclosed that has excellent water resistance in the printed area and high stability against heat in the background (Patent Document 3), but the plasticizer resistance of the printed area is not sufficient. In addition, diphenylsulfone-bridged compounds (Patent Document 4) and urea-urethane compounds (Patent Document 5) have been proposed as color-developing compounds that have high storage stability against plasticizers, but they have a problem of low thermal responsiveness.

[0006] On the other hand, a thermal recording material has been disclosed in which the storage stability of the printed area is improved by using a combination of a specific color-developing compound and a urea-urethane compound. However, when a urea-urethane compound is combined, background fogging occurs significantly when the material is stored in a high humidity environment, and therefore it has been an issue to achieve both thermal responsiveness and storage stability of the printed area and background. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 3,539,375 [Patent Document 2] Japanese Patent Application Publication No. 57-11088 [Patent Document 3] International Publication No. 2017 / 111032 [Patent Document 4] Japanese Patent Application Publication No. 08-333329 [Patent Document 5] JP 2000-143611 A [Non-patent literature]

[0008] [Non-Patent Document 1] European Journal of Medicinal Chemistry (2017), 125, 865―880 Summary of the Invention [Problem to be solved by the invention]

[0009] In contrast to the conventional techniques, the present invention has an object to provide a recording material or recording sheet which uses a non-phenolic compound as a developer, which has excellent water resistance in the printed area and good heat resistance in the background area. [Means for solving the problem]

[0010] As a result of extensive research aimed at achieving the above-mentioned object, the present inventors have newly discovered that a thermal recording material using a compound represented by the following general formula (1) as a color-developing compound has excellent water resistance in the printed area and excellent heat resistance in the background area, and have thus completed the present invention.

[0011] That is, the present invention is [1] A heat-sensitive recording material containing at least one compound represented by the following general formula (1):

[0012] [ka] (In formula (1), R 1 ~R 10 each independently represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group. [2] A heat-sensitive recording material, wherein the compound represented by general formula (1) is a compound represented by the following formula (2):

[0013] [ka] (In formula (2), R 1 ~R 3 has the same meaning as above.) [3] In the general formula (1), R 1 ~R 3 each independently represents a hydrogen atom or a methyl group. [4] A heat-sensitive recording layer comprising the heat-sensitive recording material according to any one of [1] to [3], and [5] A thermal recording paper comprising the thermal recording layer according to [4]. Regarding. Effect of the Invention

[0014] According to the present invention, it is possible to provide a heat-sensitive recording material in which the printed portion has excellent color development and water resistance, and the background portion has excellent heat resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in detail based on the embodiments, but is not limited to the embodiments shown below. The present invention relates to a heat-sensitive recording material containing the compound represented by the above general formula (1) as a color-developing compound, and a heat-sensitive recording layer and a heat-sensitive recording paper containing the same.

[0016] In one embodiment of the present invention, R 1 ~R 10 The halogen atom in the above formula (I) includes a fluorine atom, a chlorine atom or a bromine atom, and a fluorine atom or a chlorine atom is preferable.

[0017] In one embodiment of the present invention, R 1 ~R 10The alkyl group in may be a straight-chain, branched-chain or cyclic alkyl group, and among them, a straight-chain or branched-chain alkyl group is preferred, and a straight-chain alkyl group is more preferred. The carbon number range is usually C1 to C12, preferably C1 to C8, more preferably C1 to C6, and even more preferably C1 to C4. Specific examples thereof include straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl; branched-chain alkyl groups such as isopropyl, isobutyl, sec-butyl, t-butyl, isopentyl, isohexyl, and isooctyl; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0018] In one embodiment of the present invention, R 1 ~R 10 The alkoxy group in may be a straight-chain, branched-chain or cyclic alkoxy group, preferably a straight-chain or branched-chain alkoxy group, more preferably a straight-chain alkoxy group. The carbon number of the alkoxy group is usually in the range of C1 to C12, preferably C1 to C8, more preferably C1 to C6, and further preferably C1 to C4. Specific examples thereof include linear alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptoxy, n-octyloxy, n-nonyloxy, and n-decyloxy; branched (preferably C3 to C10) alkoxy groups such as isopropoxy, isobutoxy, sec-butoxy, t-butoxy, isoamyloxy, t-amyloxy, isohexyloxy, t-hexyloxy, isoheptoxy, t-heptoxy, isooctyloxy, t-octyloxy, 2-ethylhexyloxy, isononyloxy, and isodecyloxy; and cyclic (preferably C3 to C7) alkoxy groups such as cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexyloxy, and cycloheptoxy.

[0019] In one embodiment of the present invention, R 1 ~R 10The aryloxy group in is preferably a C6 to C12 aryloxy group, and specific examples thereof include phenoxy, naphthyloxy, biphenyloxy, and the like.

[0020] In one embodiment of the present invention, R 1 ~R 10 The alkylcarbonyloxy group in the formula (I) includes linear, branched, or cyclic alkylcarbonyloxy groups. Among them, C1 to C10 alkylcarbonyloxy groups are preferred. Specific examples thereof include linear alkylcarbonyloxy groups such as methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, n-butylcarbonyloxy, n-pentylcarbonyloxy, n-hexylcarbonyloxy, n-heptylcarbonyloxy, n-octylcarbonyloxy, n-nonylcarbonyloxy, and n-decylcarbonyloxy; isopropylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, t-butylcarbonyloxy, isoamylcarbonyloxy, t-amylcarbonyloxy, isohexylcarbonyloxy, and the like. Examples of the alkylcarbonyloxy groups include branched (preferably C3 to C10) alkylcarbonyloxy groups such as t-hexylcarbonyloxy, isoheptylcarbonyloxy, t-heptylcarbonyloxy, isooctylcarbonyloxy, t-octylcarbonyloxy, 2-ethylhexylcarbonyloxy, isononylcarbonyloxy, and isodecylcarbonyloxy; and cyclic (preferably C3 to C7) alkylcarbonyloxy groups such as cyclopropylcarbonyloxy, cyclobutylcarbonyloxy, cyclopentylcarbonyloxy, cyclohexylcarbonyloxy, and cycloheptylcarbonyloxy. Among these, linear or branched alkylcarbonyloxy groups are preferred, and linear alkylcarbonyloxy groups are more preferred. In one embodiment of the present invention, R 1 ~R 10The arylcarbonyloxy group in is preferably a C6 to C12 arylcarbonyloxy group, and specific examples thereof include phenylcarbonyloxy, naphthylcarbonyloxy, and biphenylcarbonyloxy.

[0021] In one embodiment of the present invention, R 1 ~R 10 The alkylcarbonylamino group in the formula (I) may be a straight-chain, branched-chain or cyclic alkylcarbonylamino group. Among these, a C1 to C10 alkylcarbonylamino group is preferred. Specific examples thereof include straight-chain alkylcarbonylamino groups such as methylcarbonylamino, ethylcarbonylamino, n-propylcarbonylamino, n-butylcarbonylamino, n-pentylcarbonylamino, n-hexylcarbonylamino, n-heptylcarbonylamino, n-octylcarbonylamino, n-nonylcarbonylamino and n-decylcarbonylamino; isopropylcarbonylamino, isobutylcarbonylamino, sec-butylcarbonylamino, t-butylcarbonylamino, isoamylcarbonylamino, t-amylcarbonylamino and isohexylcarbonylamino. branched (preferably C3 to C10) alkylcarbonylamino groups such as t-hexylcarbonylamino, isoheptylcarbonylamino, t-heptylcarbonylamino, isooctylcarbonylamino, t-octylcarbonylamino, 2-ethylhexylcarbonylamino, isononylcarbonylamino, and isodecylcarbonylamino; cyclic (preferably C3 to C7) alkylcarbonylamino groups such as cyclopropylcarbonylamino, cyclobutylcarbonylamino, cyclopentylcarbonylamino, cyclohexylcarbonylamino, and cycloheptylcarbonylamino. Among these, linear or branched alkylcarbonylamino groups are preferred, and linear alkylcarbonylamino groups are more preferred.

[0022] In one embodiment of the present invention, R 1 ~R 10The arylcarbonylamino group in is preferably a C6 to C12 arylcarbonylamino group, specific examples of which include phenylcarbonylamino, naphthylcarbonylamino, and biphenylcarbonylamino.

[0023] In one embodiment of the present invention, R 1 ~R 10 The alkylsulfonylamino group in the formula (I) may be a straight-chain, branched-chain or cyclic alkylsulfonylamino group. Among them, a C1 to C10 alkylsulfonylamino group is preferred. Specific examples thereof include straight-chain alkylsulfonylamino groups such as methylsulfonylamino, ethylsulfonylamino, n-propylsulfonylamino, n-butylsulfonylamino, n-pentylsulfonylamino, n-hexylsulfonylamino, n-heptylsulfonylamino, n-octylsulfonylamino, n-nonylsulfonylamino and n-decylsulfonylamino; isopropylsulfonylamino, isobutylsulfonylamino, sec-butylsulfonylamino, t-butylsulfonylamino, isoamylsulfonylamino, t-amylsulfonylamino and isohexylsulfonylamino. branched (preferably C3 to C10) alkylsulfonylamino groups such as t-hexylsulfonylamino, isoheptylsulfonylamino, t-heptylsulfonylamino, isooctylsulfonylamino, t-octylsulfonylamino, 2-ethylhexylsulfonylamino, isononylsulfonylamino, and isodecylsulfonylamino; cyclic (preferably C3 to C7) alkylsulfonylamino groups such as cyclopropylsulfonylamino, cyclobutylsulfonylamino, cyclopentylsulfonylamino, cyclohexylsulfonylamino, and cycloheptylsulfonylamino. Among these, linear or branched alkylsulfonylamino groups are preferred, and linear alkylsulfonylamino groups are more preferred.

[0024] In one embodiment of the present invention, R 1 ~R 10The arylsulfonylamino group in is preferably a C6 to C12 arylsulfonylamino group, specific examples of which include phenylsulfonylamino, toluenesulfonylamino, naphthylsulfonylamino, and biphenylsulfonylamino.

[0025] In one embodiment of the present invention, R 1 ~R 10 The monoalkylamino group in the above formula (I) includes linear, branched or cyclic monoalkylamino groups, and among these, mono C1 to C10 alkylamino groups are preferred. Specific examples thereof include linear monoalkylamino groups such as methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino, and n-decylamino; branched (preferably C3 to C10) monoalkylamino groups such as isopropylamino, isobutylamino, sec-butylamino, t-butylamino, isoamylamino, t-amylamino, isohexylamino, t-hexylamino, isoheptylamino, t-heptylamino, isooctylamino, t-octylamino, 2-ethylhexylamino, isononylamino, and isodecylamino; and cyclic (preferably C3 to C7) monoalkylamino groups such as cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino, and cycloheptylamino. Among these, linear or branched monoalkylamino groups are preferred, and linear monoalkylamino groups are more preferred.

[0026] In one embodiment of the present invention, R 1 ~R 10The dialkylamino group in the formula (I) may be a straight-chain, branched-chain or cyclic dialkylamino group. Among these, a di-C1-C10 alkylamino group is preferred. Specific examples thereof include straight-chain dialkylamino groups such as dimethylamino, diethylamino, di-n-propylamino, di-n-butylamino, di-n-pentylamino, di-n-hexylamino, di-n-heptylamino, di-n-octylamino, di-n-nonylamino and di-n-decylamino; diisopropylamino, diisobutylamino, di-sec-butylamino, di-t-butylamino, diisoamylamino, di-t-amylamino, diisohexylamino, di-t-hexylamino, Examples of such dialkylamino groups include branched (preferably having two C3-C10 branched) groups such as diisoheptylamino, di-t-heptylamino, diisooctylamino, di-t-octylamino, di-(2-ethylhexyl)amino, diisononylamino, and diisodecylamino; and cyclic (preferably having two C3-C7 cyclic groups) groups such as dicyclopropylamino, dicyclobutylamino, dicyclopentylamino, dicyclohexylamino, and dicycloheptylamino. Among these, linear or branched dialkylamino groups are preferred, and linear dialkylamino groups are more preferred.

[0027] In one embodiment of the present invention, R 1 ~R 10 In the above, the arylamino group may be a monoarylamino group or a diarylamino group. Among them, a mono C6-C12 arylamino group is preferred. Specific examples thereof include phenylamino (anilino), naphthylamino, biphenylamino, etc. Similarly, the arylamino group may be a di C6-C12 arylamino group. Specific examples thereof include diphenylamino, dinaphthylamino, di(biphenyl)amino, etc.

[0028] In one embodiment of the present invention, the compound represented by general formula (1) is preferably a compound represented by the above general formula (2). R in the above general formula (2) 1 ~R 3is preferably an alkyl group or a hydrogen atom, more preferably a linear C1 to C4 alkyl group or a hydrogen atom, and particularly preferably a methyl group or a hydrogen atom.

[0029] In the above general formula (1), the substitution position of the substituent represented by the following general formula (3) can be the ortho-position, meta-position, or para-position, with the para-position or meta-position being preferred.

[0030] [ka]

[0031] Specific examples of the compound according to the present invention are shown in Table 1 below, but the compound is not limited thereto.

[0032] [Table 1-1] [Table 1-2]

[0033] The compound of the present invention represented by the above general formula (1) can be obtained by a known synthesis method described, for example, in European Journal of Medicinal Chemistry (2017), 125, 865-880 (Non-Patent Document 1). [Manufacturing process]

[0034] [ka] (In the formula, R 1 ~R 10 has the same meaning as above.)

[0035] The compound of the above general formula [1-2] can be produced by reacting the compound of the general formula [1-1] with a phenyl isocyanate compound in the presence or absence of a base. The solvent used in this reaction is not particularly limited as long as it does not affect the reaction, but examples thereof include amide compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbon compounds such as methylene chloride and chloroform; aromatic hydrocarbon compounds such as benzene, toluene, and xylene; ether compounds such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and diethylene glycol diethyl ether; nitrile compounds such as acetonitrile; ketone compounds such as acetone and 2-butanone; ester compounds such as ethyl acetate and butyl acetate; sulfone compounds such as sulfolane; sulfoxide compounds such as dimethyl sulfoxide, water, etc., which may be used in admixture.

[0036] The amount of the phenyl isocyanate compound used in this reaction is usually 0.1 to 50 times by mol, and preferably 0.5 to 3 times by mol, based on the amount of the compound of the general formula [1-1].

[0037] Examples of the base that can be used in this reaction if desired include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydrogen carbonate, potassium carbonate, and cesium carbonate, and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used is 0.1 to 50 times by mole, and preferably 0.5 to 5 times by mole, relative to the compound of the general formula [1-1].

[0038] The reaction temperature for this reaction is usually −78 to 120° C., and preferably −10 to 80° C. The reaction may be carried out for 10 minutes to 24 hours.

[0039] The compound of the above general formula [1-3] can be produced by reacting the compound of the general formula [1-2] with phosphorus oxychloride, thionyl chloride, chlorosulfonic acid, oxalyl chloride, etc., in the presence or absence of a base, to obtain a sulfonyl chloride, which is then reacted with a phenol compound, or by reacting it with a phenol compound by direct dehydration condensation.

[0040] The solvent used in this reaction is not particularly limited as long as it does not affect the reaction, and examples thereof include amide compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbon compounds such as methylene chloride and chloroform; aromatic hydrocarbon compounds such as benzene, toluene, and xylene; ether compounds such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and diethylene glycol diethyl ether; nitrile compounds such as acetonitrile; ketone compounds such as acetone and 2-butanone; ester compounds such as ethyl acetate and butyl acetate; sulfone compounds such as sulfolane; sulfoxide compounds such as dimethyl sulfoxide, water, and the like, which may be used in combination.

[0041] The amount of the phenol compound used in this reaction is 0.1 to 50 times by mol, and preferably 0.7 to 3 times by mol, relative to the amount of the compound of the general formula [1-2], and the reaction temperature is usually −78 to 100° C., and preferably −20 to 80° C. The reaction time may be 10 minutes to 24 hours.

[0042] In forming the thermosensitive recording material of the present invention, the color-forming compound is usually used in an amount of 1 to 50 mass %, preferably 5 to 30 mass %, the compound represented by the above general formula (1) is usually used in an amount of 1 to 70 mass %, preferably 10 to 50 mass %, the sensitizer is usually used in an amount of 1 to 80 mass %, the storage stability improver is usually used in an amount of 0 to 30 mass %, the binder is usually used in an amount of 1 to 90 mass %, the filler is usually used in an amount of 0 to 80 mass %, and other lubricants, surfactants, antifoaming agents and ultraviolet absorbers are each used in any desired ratio, for example, usually 0 to 30 mass % each (mass % refers to the mass ratio of each component in the thermosensitive color-forming layer).

[0043] In a more preferred embodiment, the compound represented by formula (1) is used in the above composition in an amount of 0.5 to 20 times, more preferably 1 to 5 times, by mass ratio relative to the color-forming compound of 1. In the heat-sensitive recording material of the present invention, a color-developing compound, a sensitizer or other additives that are themselves known in the art may be used in combination with the above-mentioned components.

[0044] The color-forming compound used in the present invention is not particularly limited, and may be any compound generally used in pressure-sensitive recording paper or heat-sensitive recording paper.Examples of the color-forming compound used include fluoran-based compounds, triarylmethane-based compounds, spiro-based compounds, diphenylmethane-based compounds, thiazine-based compounds, lactam-based compounds, and fluorene-based compounds, and fluoran-based compounds are preferred.

[0045] Specific examples of fluoran-based compounds include 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran, 3-[N-ethyl-N-(3-ethoxypropyl)amino]-6-methyl fluoran, 3-(N-ethyl-N-hexylamino)-6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-tetrahydrofurylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(p-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-(p-fluoroanilino)fluoran fluoran, 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-7-(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-diethylamino-7-(o-fluoroanilino)fluoran, 3-dibutylamino-7-(o-fluoroanilino)fluoran, 3-diethylamino-7-(3,4-dichloroanilino)fluoran, 3-pi Examples of the fluoran include lolizino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-octylfluoran, and 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-phenethylfluoran, and 3-dibutylamino-6-methyl-7-anilinofluoran is preferred.

[0046] Specific examples of triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylaminoindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, and 3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl). Examples of such phthalides include 3,3-bis(1,2-dimethylindol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-(2-phenylindol-3-yl)-5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethylaminophthalide, and the like.

[0047] Specific examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho-(3-methoxybenzo)spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro(indoline-2,2'-benzopyran), and the like; specific examples of diphenylmethane compounds include N-halophenyl-leucoauramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucoauramine, and the like. Specific examples of thiazine compounds include benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc. Specific examples of lactam compounds include rhodamine B anilinolactam, rhodamine B p-chloroanilinolactam, etc. Specific examples of fluorene compounds include 3,6-bis(dimethylamino)fluorene spiro(9,3')-6'-dimethylaminophthalide, 3,6-bis(dimethylamino)fluorene spiro(9,3')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorene spiro(9,3')-6'-pyrrolidinophthalide, etc. These color-developing compounds can be used alone or in combination.

[0048] The color-developing compound that can be used in combination with the present invention is not particularly limited, and may be any compound that is generally used in pressure-sensitive recording paper or heat-sensitive recording paper, such as 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'-cyclohexylidene diphenol, 2,2'-bis(2,5-dibromo-4-hydroxyphenyl)propane, 4,4'-isopropylidenebis(2-t-butylphenol), 2,2'-methylenebis(4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4' phenolic compounds such as 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, and 2,4-dihydroxy-2'-methoxybenzanilide; aromatic carboxylic acid derivatives such as benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, and 3,5-di-α-methylbenzyl salicylic acid; aromatic carboxylic acids; and polyvalent metal salts thereof.

[0049] Specific examples of the sensitizer (heat-fusible compound) used in the present invention include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, aromatic ketone derivatives, and aromatic hydrocarbon compounds.

[0050] Specific examples of waxes include wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, polyethylene oxide, etc.; specific examples of higher fatty acids include stearic acid, behenic acid, etc.; specific examples of higher fatty acid amides include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide ... Examples of the anilides include stearic acid anilide and linoleic acid anilide; examples of the naphthalene derivatives include 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, and 2,6-diisopropylnaphthalene; examples of the aromatic ethers include 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methoxyphenoxy)ethane, 1,2-bis(3,4-diphenyl ether), 1,2-bis(4-phenyl ... Examples of aromatic carboxylic acid derivatives include, for example, p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, and terephthalic acid dibenzyl ester; examples of aromatic sulfonic acid ester derivatives include, for example, p-toluenesulfonic acid phenyl ester, phenyl nylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, 4-tolylmesitylenesulfonate, etc.; carbonic acid or oxalic acid diester derivatives include, for example, diphenyl carbonate, oxalic acid dibenzyl ester, oxalic acid di(4-chlorobenzyl) ester, oxalic acid di(4-methylbenzyl) ester, etc.; biphenyl derivatives include, for example, p-benzylbiphenyl, p-allyloxybiphenyl, etc.; terphenyl derivatives include, for example, m-terphenyl, etc.;Examples of the sulfone derivatives include p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide, 4,4'-diallyloxydiphenylsulfone, and diphenylsulfone; examples of the aromatic ketone derivatives include 4,4'-dimethylbenzophenone and dibenzoylmethane; examples of the aromatic hydrocarbon compounds include p-acetotoluidine;

[0051] Specific examples of the preservative used in the present invention include 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'-hydro 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'-tetramethyl Hindered phenol compounds such as diphenyl sulfone, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-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 ethylene glycol Examples of the epoxy resin include epoxy compounds such as epoxy resins, phenol novolac type epoxy resins, and bisphenol A type epoxy resins; N,N'-di-2-naphthyl-p-phenylenediamine; sodium or polyvalent metal salts of 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate; bis(4-ethyleneiminocarbonylaminophenyl)methane; urea urethane compounds (such as color developer UU manufactured by Chemipro Chemical Co., Ltd.); and diphenyl sulfone crosslinked compounds represented by the following formula (4) or mixtures thereof.

[0052] [ka] (In formula (4), a is an integer of 0 to 6.)

[0053] Specific examples of binders used in the present invention include water-soluble polymers such as 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, silyl group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, water-soluble isoprene rubber, alkali salts of styrene / maleic anhydride copolymers, and alkali salts of iso(or diiso)butylene / maleic anhydride copolymers; p) Acrylic acid ester copolymer, styrene / (meth)acrylic acid ester copolymer, polyurethane, polyester polyurethane, polyether polyurethane, polyvinyl acetate, 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 copolymer, acrylonitrile / butadiene (NB) copolymer, carboxylated acrylonitrile / butadiene (NB) copolymer, hydrophobic polymers such as colloidal silica and (meth)acrylic resin composite particles, etc. These are usually used as emulsions.

[0054] 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, polystyrene resin, and urea-formalin resin.

[0055] Furthermore, in the present invention, various additives other than those mentioned above can be used. Examples of such additives include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head wear and sticking, etc.; ultraviolet absorbents such as phenol derivatives, benzophenone compounds, and benzotriazole compounds for imparting antioxidant or anti-aging effects; and various surfactants and defoamers.

[0056] Next, the method for preparing the heat-sensitive recording material and heat-sensitive recording sheet of the present invention will be described. The color-developing compound and the compound represented by the above general formula (1) used in the present invention are separately ground and dispersed in a dispersing machine such as a ball mill, attritor, or sand mill together with a binder or, if necessary, other additives to prepare a dispersion (usually, when grinding or dispersing is performed in a wet manner, water is used as a medium), and the dispersions are mixed to prepare a heat-sensitive recording material coating solution, which is then applied to a support such as paper (plain paper, wood-free paper, coated paper, etc. can be used), a plastic sheet, or synthetic paper, usually with a dry mass of 1 to 20 g / m. 2 The mixture is then coated with a bar coater, blade coater or the like so as to obtain a thermal recording layer, which is then dried to prepare a thermal recording sheet.

[0057] If necessary, an intermediate layer may be provided between the thermosensitive recording layer and the support, or an overcoat layer (protective layer) may be provided on the thermosensitive recording layer. The intermediate layer and overcoat layer (protective layer) are prepared by, for example, crushing and dispersing the intermediate layer coating liquid or overcoat layer (protective layer) coating liquid together with the above-mentioned binder or other additives as necessary in the same manner as in the preparation of the thermosensitive recording material coating liquid, and then drying the intermediate layer coating liquid or overcoat layer (protective layer) coating liquid to a mass of usually 0.1 to 10 g / m. 2 The coating can be formed by applying the coating to a thickness of about 100 μm and drying it. EXAMPLES

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" means parts by mass, and "%" in the explanation of the solutions means % by mass.

[0059] [Synthesis Example 1] Synthesis of Compound No. 2 in Table 1 (see Non-Patent Document 1) [ka] 100 parts of 3-aminobenzenesulfonic acid [2-1] (Tokyo Chemical Industry Co., Ltd.) was added to 100 parts of DMF and stirred, and then 69 parts of phenyl isocyanate (Tokyo Chemical Industry Co., Ltd.) was added dropwise at room temperature. After stirring at the same temperature for 4 hours, the reaction solution was dropped into 250 parts of water to precipitate crystals, and [2-2] was obtained. Next, 90 parts of phosphorus oxychloride (Tokyo Chemical Industry Co., Ltd.) was added dropwise at 0°C and stirred at room temperature for 12 hours. Then, 60 parts of phenol (Tokyo Chemical Industry Co., Ltd.) was added dropwise at room temperature, 80 parts of potassium carbonate was slowly added, and stirred at room temperature for 12 hours. Then, the reaction solution was dropped into 200 parts of water to precipitate crystals, which were then washed with dichloromethane and water in that order and dried to obtain 200 parts of compound number 2 in Table 1 as a white solid. MS(ESI):[MH] - :cal.:381.4,found:381.4.

[0060] [Example 1] Preparation of thermal recording material Compound No. 2 obtained in Synthesis Example 1 and shown in Table 1 was ground and dispersed for 1 hour using a Multi-Beads Shocker (model: PV1001(S)) manufactured by Yasui Kikai Co., Ltd. in the following composition to prepare liquid [A].

[0061] [Table 2]

[0062] A mixture of the following composition was ground and dispersed using a sand grinder to a median particle size of 1 μm as measured by a laser diffraction / scattering particle size distribution analyzer LA-950 (Horiba, Ltd.) to prepare a dispersion liquid [B] of a color-forming compound. [Table 3]

[0063] Next, the above obtained solutions and the following chemicals were mixed in the following compositions to prepare coating solutions for thermal recording materials. 2 Dry weight of 5g / m2 on wood-free paper 2 The resulting mixture was then dried to form a heat-sensitive recording layer. [Table 4]

[0064] (Formation of protective layer) Next, a protective layer coating solution having the following composition is applied onto the thermal recording layer so that the dry weight is 2 g / m 2 The coating was then dried to prepare a thermal recording paper with a protective layer. [Table 5]

[0065] [Comparative Example 1] A mixture of the following composition was ground and dispersed using a sand grinder to a median particle size of 1 μm as measured with a laser diffraction / scattering particle size distribution analyzer LA-950 (Horiba, Ltd.) to prepare liquid [C]. A comparative thermal recording paper with a protective layer was obtained in the same manner as in Example 1, except that, of the composition of the thermal recording layer coating liquid described in Example 1 above, liquid [C] was used instead of liquid [A] and mixed in the following composition ratio to prepare a thermal recording material coating liquid. [Table 6]

[0066] [Water resistance evaluation test] The thermal recording papers obtained in Example 1 and Comparative Example 1 were printed with a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd. with a pulse width of 1.2 msec, and the samples were immersed in water at 25°C for 24 hours. The Macbeth reflection density of the colored portion of the sample before and after the test was measured using a colorimeter manufactured by Gretag-Macbeth, product name "SpectroEye". The color measurements were performed 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 retention rate, the better the water resistance. The retention rate was calculated using the following calculation formula (I). Residual rate (%) = (Macbeth reflection density of the colored part of the sample after the test) / (Macbeth reflection density of the colored part of the sample before the test) × 100 (I)

[0067] [Table 7]

[0068] As is clear from Table 2 above, Example 1, in which the compound of the present invention was used as the color-developing compound, had a higher retention rate than Comparative Example 1, in which bisphenol S, a color-developing compound described in Patent Document 2, was used, and it can be said that the present invention has superior water resistance to the color-developing part compared to the prior art.

[0069] [Heat resistance evaluation test for scalp] The thermal recording papers obtained in Example 1 and Comparative Example 1 were kept at 90°C for 1 hour using a constant temperature incubator with a blower (trade name: DKN402) manufactured by Yamato Scientific Co., Ltd. The ISO whiteness of the background before and after the test was measured using a colorimeter (trade name: SpectroEye) manufactured by Gretag-Macbeth. The colorimeter was 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 smaller the change in ISO whiteness before and after the test, the more excellent the heat resistance of the background.

[0070] [Table 8]

[0071] As is clear from Table 3 above, Example 1, which uses the color-developing compound of the present invention, has a small change in ISO whiteness before and after the heat resistance test, and therefore has superior heat resistance of the background compared to Comparative Example 1, which uses bisphenol S, a color-developing compound described in Patent Document 2.

Claims

1. A heat-sensitive recording material comprising a compound represented by the following general formula (1): 【Chemistry 1】 (In formula (1), R １ ~R 10 each independently represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.

2. 2. The heat-sensitive recording material according to claim 1, wherein the compound represented by formula (1) is a compound represented by the following formula (2): 【Chemistry 2】 (In formula (2), R 1 ~R ３ has the same meaning as above.)

3. In the general formula (2), R 1 ~R ３ 3. The heat-sensitive recording material according to claim 1, wherein each of the groups independently represents a hydrogen atom or a methyl group.

4. A thermosensitive recording layer comprising the thermosensitive recording material according to claim 1 .

5. A thermal recording paper comprising the thermal recording layer according to claim 4.

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