Thermal recording material

Abstract

Disclosed is a thermal recording material characterized by including at least one compound represented by general formula (1). (In formula (1), R1 to R10, R21, and R22 each independently represent 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.) In formula (1), two or more of R1 to R5 may be hydrogen atoms and two or more of R6 to R10 may be hydrogen atoms. In formula (1), R4 and R5 may be hydrogen atoms and R9 and R10 may be hydrogen atoms.

Description

thermal recording materials

[0001] The present invention relates to a heat-sensitive recording material that utilizes color development due to the reaction between a color-forming dye and a color-developing compound, and to a compound suitable for use in the heat-sensitive recording material. In particular, the present invention relates to a heat-sensitive recording material that preferably has excellent heat resistance in the background and excellent water resistance, plasticizer resistance, and / or oil resistance in the printed area, and to a compound suitable for use in the heat-sensitive recording material.

[0002] Thermal recording materials are generally prepared by dispersing a leuco dye and a color-developing compound, such as a phenolic compound, separately into fine particles, mixing the two, and adding additives such as binders, sensitizers, fillers, and lubricants to obtain a coating solution, which is then coated onto paper, film, synthetic paper, or the like. In thermal recording materials, a color record is obtained by heating the leuco dye and / or the color-developing compound, which melt and contact each other, resulting in a chemical reaction. To develop the color in such thermal recording materials, a thermal printer with a built-in thermal head is typically used. Compared to other recording methods, this thermal recording method has several advantages: (1) no noise during recording, (2) no need for development or fixing, (3) no maintenance, and (4) relatively low cost. For these reasons, it is widely used in fields such as facsimiles, computer output, printers for calculators, medical measurement recorders, automatic ticket vending machines, and thermal recording labels.

[0003] In recent years, as the range of uses for thermal recording materials has expanded, the demand for high-speed recording has become even stronger in order to further improve productivity. Therefore, there is a strong demand for the development of thermal recording materials that are capable of high-speed recording and have excellent thermal responsiveness. In this case, a color-developing compound with a low melting point and a small heat of fusion is required. However, this property can easily cause the unrecorded areas (background) of the thermal recording material to deteriorate during production, use, or storage, resulting in background fogging (unwanted color development on the background). Therefore, there is a demand for not only high whiteness but also improved stability of the background of the thermal recording material.

[0004] Generally, color-developing compounds having a phenolic hydroxyl group have high color-developing ability. Among these, many bisphenol-based color-developing compounds have been reported due to their high color density, including, for example, 2,2-bis(4-hydroxyphenylpropane) (bisphenol A) disclosed in Patent Document 1 and 4,4'-dihydroxydiphenyl sulfone (bisphenol S) disclosed in Patent Document 2. However, these color-developing compounds having a phenolic hydroxyl group have drawbacks such as poor thermal response due to their high melting points and poor water resistance of printed areas. Furthermore, the use of phenolic compounds such as bisphenol A has been problematic due to endocrine problems, and there is a demand for non-phenolic color-developing compounds that do not contain a phenol structure.

[0005] Various non-phenolic color-developing compounds, such as diphenylurea-based and sulfonylurea-based compounds, have been proposed (Patent Documents 3 to 6). However, thermal recording materials using these color-developing compounds have drawbacks, such as poor thermal stability of the background and low plasticizer resistance of the printed area. When exposed to heat for a relatively short period of time or when used as food labels, the colored image fades or disappears, limiting their potential for wider applications. Therefore, no color-developing compound has yet been found that satisfies market demands in a balanced manner. In particular, there is a strong demand for the development of a thermal recording material that exhibits excellent heat resistance of the background and excellent plasticizer resistance of the printed area.

[0006] US Patent No. 3539375 JP 57-11088 JP 8-59603 JP 8-156426 WO 2014 / 080615 WO 2019 / 044462

[0007] One object of the present invention is to provide a thermal recording material which has excellent heat resistance in the background and excellent water resistance and / or plasticizer resistance and / or oil resistance in the printed area. Another object of the present invention is to provide a thermal recording layer containing such a thermal recording material, and thermal recording paper or thermal film containing this thermal recording layer. A further object of the present invention is to provide a novel compound which can be used as a color-developing compound.

[0008] As a result of extensive research into achieving the above-mentioned object, the present inventors have newly discovered that a compound having a certain specific structure can solve the above-mentioned problems, and that a thermal recording material using this compound as a color-developing compound has excellent heat resistance of the background and excellent water resistance, plasticizer resistance, and oil resistance of the printed area, and preferably all of these properties, and have thus completed the present invention.

[0009] Various aspects and embodiments of the present invention relate to the following items [1] to [7]: [1] A heat-sensitive recording material characterized by containing at least one compound represented by the following general formula (1): (In the formula, R １ ~R １０ , R ２１ , and R ２２ 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] In the formula (1), R １ ~R ５ Two or more of R are hydrogen atoms, and ６ ~R １０ [3] In the formula (1), two or more of R are hydrogen atoms. ４ and R ５ is a hydrogen atom, and R ９ and R １０ is a hydrogen atom, provided that R １ ~R ３ , R ６ ~R ８ , R ２１ , and R ２２ [4] In the formula (1), R ３ and R ８ are each independently a hydrogen atom or an alkyl group, and R １ , R ２ , R４ ~R ７ , R ９ , R １０ , R ２１ and R ２２ is a hydrogen atom. [5] A thermosensitive recording material according to the above [1]. [6] A thermosensitive recording paper or a thermosensitive film comprising the thermosensitive recording material according to any one of the above [1] to [4]. [7] A compound represented by the following general formula (2): (In the formula, R １ ~R １０ , R ２１ , and R ２２ 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.

[0010] According to one aspect of the present invention, by using at least one compound represented by general formula (1) as a color-developing compound, a thermal recording material can be provided which has excellent heat resistance in the background and excellent water resistance, plasticizer resistance, and / or oil resistance in the printed area. Because of the above-mentioned excellent properties, such a thermal recording material can be suitably used for a thermal recording layer, and thermal recording paper or thermal film containing a thermal recording layer. Furthermore, according to another aspect of the present invention, a novel compound represented by general formula (2) is provided which can be used as a color-developing compound.

[0011] The present invention relates to a heat-sensitive recording material that contains a color-forming compound that is usually colorless or pale in color, a color-developing compound represented by the above formula (1), and optionally contains other color-developing compounds, a sensitizer, a storage stability improver, and further contains the following binder, and optionally a filler, other additives, etc.

[0012] [Compound represented by formula (1)] R of formula (1) １ ~R １０, R ２１ , and R ２２ Examples of the halogen atom in the formula (I) include a fluorine atom, a chlorine atom, and a bromine atom, with a fluorine atom and a chlorine atom being preferred.

[0013] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The alkyl group in the formula (I) may be a straight-chain, branched-chain, or cyclic alkyl group. Of these, a straight-chain or branched-chain group is preferred, and a straight-chain 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 of the alkyl group 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. Of these, preferred are methyl, ethyl, and n-propyl, more preferred are methyl and ethyl, and particularly preferred is methyl.

[0014] R in formula (1) １ ~R １０ , R ２１ , and R ２２The alkoxy group in the formula (I) may be a straight-chain, branched-chain, or cyclic alkoxy group. Of these, a straight-chain or branched-chain alkoxy group is preferred, and a straight-chain alkoxy 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 of the alkoxy group include straight-chain alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptoxy, n-octyloxy, n-nonyloxy, and n-decyloxy; branched-chain (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. Of these, methoxy, ethoxy and n-propoxy are preferred, methoxy and ethoxy are more preferred, and methoxy is particularly preferred.

[0015] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The aryloxy group in the formula (I) is not particularly limited as long as it has a structure in which an aromatic hydrocarbon is bonded via an oxygen atom. The aromatic hydrocarbon can be arbitrarily selected from, for example, a monocyclic structure, a polycyclic structure, a condensed ring structure, a heterocyclic structure, etc. Examples of aromatic hydrocarbons constituting the aryloxy group include benzene, pyrrole, thiophene, furan, naphthalene, anthracene, biphenyl, indole, etc. These aromatic hydrocarbons may further have a substituent. R １ The aryloxy group in may be, for example, phenoxy, naphthyloxy, anthracenoxy, halogenated phenoxy, alkylphenoxy, biphenoxy, etc. Preferably, it is a C6 to C12 aryloxy group, and specific examples include phenoxy, naphthyloxy, biphenoxy, etc.

[0016] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The alkylcarbonyloxy group in the formula (I) includes a straight-chain, branched-chain, or cyclic alkylcarbonyloxy group, and is preferably a C1 to C10 alkylcarbonyloxy group. Specific examples of the alkylcarbonyloxy group include straight-chain 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, and iso Branched chain (preferably C3 to C10) alkylcarbonyloxy groups such as hexylcarbonyloxy, 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. Of these, linear or branched alkylcarbonyloxy groups are preferred, and linear alkylcarbonyloxy groups are more preferred.

[0017] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The arylcarbonyloxy group in may be preferably a C6 to C12 arylcarbonyloxy group. Specific examples of the arylcarbonyloxy group include phenylcarbonyloxy, naphthylcarbonyloxy, biphenylcarbonyloxy, etc. Of these, the phenylcarbonyloxy group is preferred.

[0018] R in formula (1)１ ~R １０ , R ２１ , and R ２２ The alkylcarbonylamino group in the formula (I) includes linear, branched, or cyclic alkylcarbonylamino groups, and is preferably a C1 to C10 alkylcarbonylamino group. Specific examples of the alkylcarbonylamino group include linear ones 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 iso Examples of the alkylcarbonylamino group include branched (preferably C3 to C10) groups such as hexylcarbonylamino, t-hexylcarbonylamino, isoheptylcarbonylamino, t-heptylcarbonylamino, isooctylcarbonylamino, t-octylcarbonylamino, 2-ethylhexylcarbonylamino, isononylcarbonylamino, and isodecylcarbonylamino; and cyclic (preferably C3 to C7) groups such as cyclopropylcarbonylamino, cyclobutylcarbonylamino, cyclopentylcarbonylamino, cyclohexylcarbonylamino, and cycloheptylcarbonylamino. Preferred are linear or branched alkylcarbonylamino groups, more preferably linear alkylcarbonylamino groups. Of the linear alkylcarbonylamino groups, preferred are methylcarbonylamino, ethylcarbonylamino, and n-propylcarbonylamino groups, more preferably methylcarbonylamino and ethylcarbonylamino groups, and particularly preferably methylcarbonylamino groups.

[0019] R in formula (1) １ ~R １０ , R ２１ , and R ２２The arylcarbonylamino group in may be preferably a C6 to C12 arylcarbonylamino group. Specific examples of the arylcarbonylamino group include a phenylcarbonylamino group, a naphthylcarbonylamino group, and a biphenylcarbonylamino group. Of these, the phenylcarbonylamino group is preferred.

[0020] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The alkylsulfonylamino group in the formula (I) may be a straight-chain, branched-chain, or cyclic alkylsulfonylamino group, and may preferably be a C1 to C10 alkylsulfonylamino group. Specific examples of the alkylsulfonylamino group 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 isopropylsulfonylamino. branched-chain (preferably C3 to C10) sulfonylamino groups such as 2-ethylhexylsulfonylamino, t-hexylsulfonylamino, isoheptylsulfonylamino, t-heptylsulfonylamino, isooctylsulfonylamino, t-octylsulfonylamino, 2-ethylhexylsulfonylamino, isononylsulfonylamino, and isodecylsulfonylamino; and cyclic (preferably C3 to C7) sulfonylamino groups such as cyclopropylsulfonylamino, cyclobutylsulfonylamino, cyclopentylsulfonylamino, cyclohexylsulfonylamino, and cycloheptylsulfonylamino. Of these, preferred are linear or branched-chain alkylsulfonylamino groups, and more preferred are linear alkylsulfonylamino groups.

[0021] R in formula (1) １ ~R １０ , R ２１ , and R ２２The arylsulfonylamino group in may be preferably a C6 to C12 arylsulfonylamino group. Specific examples of the arylsulfonylamino group include phenylsulfonylamino, toluenesulfonylamino, naphthylsulfonylamino, biphenylsulfonylamino, etc.

[0022] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The monoalkylamino group in the formula (I) may be a straight-chain, branched-chain, or cyclic monoalkylamino group, and is preferably a mono-C1 to C10 alkylamino group. Specific examples of the monoalkylamino group include straight-chain groups such as methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino, and n-decylamino; branched-chain (preferably C3 to C10) 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) groups such as cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino, and cycloheptylamino. Preferably, the polymer is a straight chain or branched chain, more preferably a straight chain.

[0023] R in formula (1) １ ~R １０ , R ２１ , and R ２２The dialkylamino group in the formula (I) may be a straight-chain, branched-chain, or cyclic dialkylamino group, and may preferably be a di-C1 to C10 dialkylamino group. Specific examples of the dialkylamino group include straight-chain ones 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, and di-t-heptylamino; Examples of the alkylamino group include branched amino groups (preferably having two C3 to C10 branched chains) such as dicyclopropylamino, dicyclobutylamino, dicyclopentylamino, dicyclohexylamino, dicycloheptylamino, and dicycloheptylamino. These alkylamino groups are preferably straight-chain or branched, and more preferably straight-chain.

[0024] R in formula (1) １ ~R １０ , R ２１ , and R ２２ The arylamino group in may be a monoarylamino group or a diarylamino group, and is preferably a mono C6-C12 arylamino group or a di C6-C12 arylamino group. Specific examples of the arylamino group include phenylamino (anilino), naphthylamino, biphenylamino, diphenylamino, dinaphthylamino, and di(biphenyl)amino.

[0025] The substituent R in the present invention １ ~R 10 As the group, a hydrogen atom, a methyl group, or a phenyl group is particularly preferred.

[0026] Preferred examples of the compound represented by formula (1) are listed below. i) R １ ~R ５Two or more of R are hydrogen atoms, and ６ ~R １０ ii) A compound in which two or more of R １ ~R ５ Two of the groups are hydrogen atoms, and R ６ ~R １０ iii) Compounds in which two of R are hydrogen atoms. ４ and R ５ is a hydrogen atom, and R ９ and R １０ is a hydrogen atom. １ , R ２ , R ４ ~R ７ , R ９ and R １０ is a hydrogen atom. ３ and R ８ are each independently a hydrogen atom or an alkyl group, and R １ , R ２ , R ４ ~R ７ , R ９ and R １０ is a hydrogen atom. ３ and R ８ is a hydrogen atom or a methyl group, and R １ , R ２ , R ４ ~R ７ , R ９ and R １０ is a hydrogen atom. １ ~R １０ A compound in which all atoms are hydrogen atoms.

[0027] The compound represented by formula (1) according to the present invention may be any of the compounds listed as specific examples in Tables 1 to 6 below, but is not limited thereto.

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034] [Method for producing the compound represented by formula (1)] The compound represented by formula (1) can be synthesized by any of the following four methods, without any particular limitation: <Production method 1> The compound represented by formula (1) can be synthesized according to the following reaction route. R in the above formulas [1-1] to [1-3] １ ~R １０ , R ２１ , R ２２ is R in the above formula (1). １ ~R １０ , R ２１ , R ２２ is synonymous with.

[0035] The compound of general formula [1-2] can be produced by reacting the compound of general formula [1-1] with phosgene or triphosgene, urea, or a chloroformate, in the presence or absence of a base. The compound of formula [1-1] is available, for example, as sulfanilic acid from Tokyo Chemical Industry Co., Ltd. (see Chemical Communications (Cambridge, United Kingdom) (2020), 56(18), 2735-2738; Communications (2018), 48(3), 247-254).

[0036] The solvent used in this reaction is not particularly limited as long as it does not affect the reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbons such as methylene chloride and chloroform; aromatic hydrocarbons such as toluene, xylene, and mesitylene; ethers such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and diethylene glycol diethyl ether; nitriles such as acetonitrile; ketones such as acetone and 2-butanone; esters such as ethyl acetate and butyl acetate; sulfones such as sulfolane; sulfoxides such as dimethyl sulfoxide, and water. Two or more of these solvents may be mixed and used.

[0037] The amount of phosgene or triphosgene, urea, or chloroformate used in this reaction is usually 0.1 to 50 times by mole, preferably 0.2 to 20 times by mole, and more preferably 0.4 to 1.3 times by mole, relative to the amount of the compound of the general formula [1-1].

[0038] Examples of the base optionally used in this reaction include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, and cesium carbonate; and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used may be 0.01 to 50 times, and preferably 0.1 to 2 times, the molar amount of the compound of general formula [1-1].

[0039] The reaction temperature for this reaction may usually be −10 to 250° C., preferably 0 to 200° C. The reaction may be carried out for, for example, 10 minutes to 48 hours.

[0040] The compound of formula [1-3] can be produced by reacting the compound of formula [1-2] with phosphorus oxychloride, thionyl chloride, chlorosulfonic acid, oxalyl chloride, phosphorus pentachloride, or the like in the presence or absence of a base to obtain a sulfonyl chloride, which is then reacted with a phenol, or by reacting the compound of formula [1-2] with a phenol by direct dehydration condensation. The solvent used in this reaction is not particularly limited as long as it does not affect the reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbons such as methylene chloride and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and diethylene glycol diethyl ether; nitriles such as acetonitrile; ketones such as acetone and 2-butanone, esters such as ethyl acetate and butyl acetate, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, and water. Two or more of these solvents may be mixed and used.

[0041] The amount of the phenol used in this reaction may be 0.1 to 50 times, and preferably 0.7 to 3 times, the molar amount of the compound of general formula [1-2]. The reaction temperature may usually be −78 to 200° C., and preferably −20 to 120° C. The reaction may be carried out for, for example, 10 minutes to 24 hours.

[0042] <Production Method 2> The compound represented by the above formula (1) can be synthesized according to the following reaction route. R in the above formulas [2-1] and [2-2] １ ~R １０ , R ２１ , R ２２ is R in the above formula (1). １ ~R １０ , R ２１ , R ２２ is synonymous with.

[0043] The compound of general formula [2-2] can be produced by reacting the compound of general formula [2-1] with phosgene, triphosgene, urea, chloroformate, or the like in the presence or absence of a base. The compound of formula [2-1] can be synthesized by a known method using aminobenzenesulfonic acid (obtained from Tokyo Chemical Industry Co., Ltd.) and a phenol compound as starting materials. The solvent used in this reaction is not particularly limited as long as it does not affect the reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; halogenated hydrocarbons such as methylene chloride and chloroform; aromatic hydrocarbons such as toluene, xylene, and mesitylene; ethers such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and diethylene glycol diethyl ether; nitriles such as acetonitrile; ketones such as acetone and 2-butanone; esters such as ethyl acetate and butyl acetate; sulfones such as sulfolane; sulfoxides such as dimethyl sulfoxide; and water. Two or more of these solvents may be mixed and used.

[0044] Examples of the base optionally used in this reaction include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, and cesium carbonate; and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used may be 0.01 to 50 times, and preferably 0.1 to 2 times, the molar amount of the compound of general formula [2-1].

[0045] The reaction temperature for this reaction may usually be −10 to 250° C., preferably 0 to 200° C. The reaction may be carried out for, for example, 10 minutes to 48 hours.

[0046] <Production Method 3> The compound represented by the above formula (1) can be synthesized according to the following reaction route. R in the above formulas [3-1] to [3-3] １ ~R１０ , R ２１ , R ２２ is R in the above formula (1). １ ~R １０ , R ２１ , R ２２ is synonymous with.

[0047] The compound of general formula [3-3] can be produced by reacting a compound of general formula [3-1] with a compound of general formula [3-2] in the presence or absence of a base. The compound of formula [3-1] can be synthesized by a known method using the compound of formula [2-1] as a starting material. The solvent used in this reaction is not particularly limited as long as it does not affect the reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone; halogenated hydrocarbons such as methylene chloride or chloroform; aromatic hydrocarbons such as toluene, xylene, or mesitylene; ethers such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, or diethylene glycol diethyl ether; nitriles such as acetonitrile; ketones such as acetone or 2-butanone; esters such as ethyl acetate or butyl acetate; sulfones such as sulfolane; sulfoxides such as dimethyl sulfoxide; and water. These solvents may be used in combination of two or more.

[0048] Examples of the base optionally used in this reaction include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, and cesium carbonate; and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used may be 0.01 to 50 times, and preferably 0.1 to 2 times, the molar amount of the compound of general formula [3-1].

[0049] The reaction temperature for this reaction may usually be −10 to 200° C., preferably 0 to 120° C. The reaction may be carried out for, for example, 10 minutes to 24 hours.

[0050] <Production Method 4> The compound represented by the above formula (1) can be synthesized according to the following reaction route. R in the above formulas [4-1] to [4-3] １ ~R １０ , R ２１ , R ２２ is R in the above formula (1). １ ~R １０ , R ２１ , R ２２ Also, R １１ represents an alkyl group or an aryl group. １１ may be, for example, a methyl group, an ethyl group, a phenyl group, a chlorophenyl group, a nitrophenyl group, etc. １１ is not particularly limited as long as it is a group that does not hinder the synthesis of the compound [4-3].

[0051] The compound of general formula [4-3] can be produced by reacting a compound of general formula [4-1] with a compound of general formula [4-2] in the presence or absence of a base. The compound of formula [4-1] can be synthesized by a known method using the compound of formula [2-1] or [3-1] as a starting material. The solvent used in this reaction is not particularly limited as long as it does not affect the reaction. Examples of the solvent include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone; halogenated hydrocarbons such as methylene chloride or chloroform; aromatic hydrocarbons such as toluene, xylene, or mesitylene; ethers such as dioxane, tetrahydrofuran, anisole, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, or diethylene glycol diethyl ether; nitriles such as acetonitrile; ketones such as acetone or 2-butanone; esters such as ethyl acetate and butyl acetate; sulfones such as sulfolane; sulfoxides such as dimethyl sulfoxide; and water. These solvents may be used in combination of two or more.

[0052] Examples of the base optionally used in this reaction include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, and cesium carbonate; and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used may be 0.01 to 50 times, and preferably 0.1 to 2 times, the molar amount of the compound of general formula [4-1].

[0053] The reaction temperature for this reaction may usually be −10 to 200° C., preferably 0 to 120° C. The reaction may be carried out for, for example, 10 minutes to 24 hours.

[0054] [Thermal Recording Material] The thermal recording material of the present invention typically contains a color-developing compound including the compound represented by formula (1) above, and a color-forming compound. Other known color-developing compounds, sensitizers, binders, shelf-life improvers, fillers, and other additives may also be used. To form the thermal recording material of the present invention, the color-forming compound is typically used in an amount of 1 to 50% by weight, preferably 5 to 30% by weight; the compound represented by formula (1) is typically used in an amount of 1 to 70% by weight, preferably 10 to 50% by weight; the sensitizer is typically used in an amount of 0 to 80% by weight, preferably 1 to 80% by weight; the shelf-life improver is typically used in an amount of 0 to 30% by weight; the binder is typically used in an amount of 0 to 90% by weight, preferably 1 to 90% by weight; the filler is typically used in an amount of 0 to 80% by weight; and other lubricants, surfactants, antifoaming agents, and ultraviolet absorbers are each used in any proportion, for example, in an amount of 0 to 30% by weight (where "mass %" refers to the mass percentage of each component in the thermal color-forming layer). However, the total content of the color-forming compound, the compound represented by the above formula (1), and other optional components constituting the heat-sensitive recording material is 100% by mass.

[0055] In a more preferred embodiment, the compound represented by formula (1) can be used in a mass ratio of usually 0.5 to 20 times, more preferably 1 to 5 times, the mass of the color-forming compound.

[0056] <Color-forming compound> The color-forming compound used in the present invention is not particularly limited, as long as it is 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.Among these, fluoran-based compounds are preferred.

[0057] Specific examples of fluoran 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, and 3-[N-ethyl-N-(3-ethoxypropyl)amino] -6-methyl-7-anilinofluoran, 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, 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- Examples thereof include (3,4-dichloroanilino)fluoran, 3-pyrrolidino-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. Among these, 3-dibutylamino-6-methyl-7-anilinofluoran is preferred.

[0058] 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).

[0033] 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, and 3-p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethylaminophthalide.

[0059] 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), etc. Specific examples of diphenylmethane compounds include N-halophenyl-leucoauramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenylleucoauramine, etc. Specific examples of thiazine compounds include benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc. Specific examples of lactam compounds include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam. 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, and 3-dimethylamino-6-diethylaminofluorene spiro(9,3')-6'-pyrrolidinophthalide. These color-forming compounds may be used alone or in combination of two or more.

[0060] <Other Color-Developer Compounds> The heat-sensitive recording material of the present invention contains the compound represented by (1) above as a color-developing compound, but may also use one or a mixture of two or more other color-developing compounds in combination. The color-developing compounds that can be used in combination with the compound represented by (1) above as a color-developing compound are not particularly limited, and may be any compounds that are generally used in pressure-sensitive recording paper or heat-sensitive recording paper.Other color-developing compounds include, for example, α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, p-t-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'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone phenolic compounds such as 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; benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, 5-hydroxybenzoic acid, methyl 4-hydroxybenzoate ...phthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, methyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, methyl 4-hydroxyphthalate, aromatic carboxylic acid derivatives such as ethyl 4-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, and 3,5-di-α-methylbenzylsalicylic acid; aromatic carboxylic acids or polyvalent metal salts thereof; and urea compounds such as [3-(3-phenylureido)phenyl]-4-methylbenzenesulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide, N-p-toluenesulfonyl-N'-3-(p-toluenesulfonyloxy)phenylurea and diphenylurea.

[0061] <Sensitizer> Specific examples of sensitizers (heat-fusible compounds) that may be used in the heat-sensitive recording material of 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, sulfonic acid derivatives, aromatic ketone derivatives, aromatic hydrocarbon compounds, etc. These sensitizers may be used alone or in combination of two or more.

[0062] <Waxes> Specific examples of waxes that may be used in the thermal recording material of the present invention include Japan wax, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax, and oxidized polyethylene; higher fatty acids such as stearic acid and behenic acid; higher fatty acid amides such as stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, and ethylenebisstearic acid amide; and higher fatty acid anilides such as Examples of naphthalene derivatives include 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 2,6-diisopropylnaphthalene, and the like; examples of 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-dimethylphenyl)ethane, 1-phenoxy-2-(4-chlorophenoxy)ethane, and the like. Examples of aromatic carboxylic acid derivatives include p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, and terephthalic acid dibenzyl ester. Examples of aromatic sulfonic acid ester derivatives include p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, and 4-tolylmesitylenesulfonate. Examples of carbonic acid or sulfuric acid derivatives include toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate, and 4-tolylmesitylenesulfonate. Examples of oxalic acid diester derivatives include diphenyl carbonate, oxalic acid dibenzyl ester, oxalic acid di(4-chlorobenzyl) ester, and oxalic acid di(4-methylbenzyl) ester; examples of biphenyl derivatives include p-benzylbiphenyl and p-allyloxybiphenyl; examples of terphenyl derivatives include m-terphenyl; and examples of sulfone derivatives include p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide, 4,4'-diallyloxydiphenyl sulfone, and diphenyl sulfone;Examples of aromatic ketone derivatives include 4,4'-dimethylbenzophenone and dibenzoylmethane; examples of aromatic hydrocarbon compounds include p-acetotoluidine. These waxes may be used alone or in combination of two or more.

[0063] <Storability Improver> Specific examples of the storage stability improver that may be used in the heat-sensitive recording material of the present invention include 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-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-tert-butylphenyl)butane, tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate, 4,4'-thiobis(3-methylphenol), 4,4'-dihydroxy-3,3',5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3',5 hindered phenol compounds such as 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4'-(2-methylglycidyloxy)diphenyl sulfone, diglycidyl terephthalate, cresol novolac type olefins, and the like; Examples of epoxy compounds include epoxy resins, phenol novolac epoxy resins, and bisphenol A epoxy resins; N,N'-di-2-naphthyl-p-phenylenediamine, sodium or polyvalent metal salts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate, bis(4-ethyleneiminocarbonylaminophenyl)methane, urea urethane compounds (such as color-developing compound "UU" manufactured by Chemipro Chemical Co., Ltd.), and diphenyl sulfone-bridged compounds represented by the following formula (3) or mixtures thereof.These preservatives may be used alone or in combination of two or more.

[0064] (In the formula, a is an integer of 0 to 6.)

[0065] <Binder> Specific examples of binders that may be used in the present invention include water-soluble binders 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, polyvinyl pyrrolidone, 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, or (meth)acrylic Examples of binders include acrylic acid ester copolymers, styrene / (meth)acrylic acid ester copolymers, polyurethanes, polyester polyurethanes, polyether polyurethanes, polyvinyl acetate, ethylene / vinyl acetate copolymers, polyvinyl chloride, vinyl chloride / vinyl acetate copolymers, polyvinylidene chloride, polystyrene, styrene / butadiene (SB) copolymers, carboxylated styrene / butadiene (SB) copolymers, styrene / butadiene / acrylic acid copolymers, acrylonitrile / butadiene (NB) copolymers, carboxylated acrylonitrile / butadiene (NB) copolymers, and hydrophobic polymer emulsions such as composite particles of colloidal silica and (meth)acrylic resin. These binders may be used alone or in combination of two or more.

[0066] <Filler> Specific examples of fillers that may be 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, urea-formalin resin, etc. These fillers may be used alone or as a mixture of two or more.

[0067] Furthermore, various additives other than those mentioned above can be used in the present invention. Examples of such additives include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purposes of preventing thermal head wear and sticking, ultraviolet absorbers such as phenol derivatives, benzophenone compounds, and benzotriazole compounds for providing antioxidant or anti-aging effects, various surfactants, and antifoaming agents. These additives may be used alone or in combination.

[0068] [Method for preparing a thermal recording material] A typical example of a method for preparing a thermal recording material of the present invention will now be described. The color-forming compound and the compound represented by formula (1) used in the present invention are separately pulverized and dispersed in a dispersing machine such as a ball mill, attritor, or sand mill together with a binder and, if necessary, other additives to prepare dispersions (usually, water is used as a medium when pulverization or dispersion is carried out wet), and these dispersions are then mixed to prepare a thermal recording material coating liquid, which is then applied to a support such as paper (plain paper, wood-free paper, coated paper, etc.), a plastic sheet, or synthetic paper in an amount of usually 0.1 to 20 g / m2 in dry weight. ２ The thermal recording layer containing the thermal recording material of the present invention, and thermal recording paper or thermal recording film having the thermal recording layer can be prepared by applying the coating solution using a bar coater, blade coater, or the like so that the coating solution has a thickness of 100 μm or more and drying the coating solution.

[0069] If necessary, an intermediate layer may be provided between the thermosensitive recording layer and the support, and / or an overcoat layer (protective layer) may be provided on the thermosensitive recording layer. The intermediate layer and the overcoat layer (protective layer) are prepared by, for example, pulverizing and dispersing the intermediate layer coating liquid or the overcoat layer (protective layer) coating liquid together with the above-mentioned binder and / or other additives as required in the same manner as in the preparation of the thermosensitive recording material coating liquid, and then coating the intermediate layer coating liquid or the overcoat layer (protective layer) coating liquid in a dry weight of usually 0.1 to 10 g / m ２ The thermosensitive recording paper or thermosensitive recording film of the present invention can be produced by a process including coating the composition to a desired thickness and drying the coating.

[0070] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In the examples, "parts" refers to parts by mass, and "%" in the explanation of solutions refers to % by mass.

[0071] Example 1: Synthesis of Compound No. 1 in Table 1 [Step 1] To 100 parts of DMF, 100.0 parts of 3-aminobenzenesulfonic acid (the above-mentioned compound [1-1]: obtained from Tokyo Chemical Industry Co., Ltd.) and 40 parts of urea were added, and the mixture was stirred at 160°C for 12 hours. After that, the reaction solution was added dropwise to 250 parts of water to precipitate crystals. The crystals were washed successively with methanol and water, and then dried to obtain 70 parts of the above-mentioned compound [1-2] as a pale yellowish white solid. MS (ESI): [M-H] － :cal. :371.4, found:371.4. [Step 2] 30.0 parts of compound [1-2] were added to 100 parts of DMF and stirred, and then 22 parts of thionyl chloride were added dropwise and reacted at room temperature for 2 hours. Next, a DMF solution of 35 parts of phenol was added, and the mixture was stirred at 65°C for 2 hours. The reaction solution was then added dropwise to 250 parts of water to precipitate crystals. The precipitate was filtered off, washed with methanol and water, and dried to obtain the compound [1-3] (32 parts) as a pale yellowish white solid. MS (ESI): [M+H] ＋ :cal. :525.6, found:525.6.

[0072] Example 2: Preparation of thermal recording material Compound No. 1 obtained in 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 the following solution [A].

[0073] Solution [A]: Compound No. 1 listed in Table 1 15 parts 25% aqueous PVA solution 20 parts Water 65 parts

[0074] 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 (manufactured by Horiba, Ltd.) to prepare a dispersion liquid [B] of a color-forming compound. [B] Solution: 35 parts 3-dibutylamino-6-methyl-7-anilinofluoran, 40 parts 15% aqueous PVA solution, 25 parts water

[0075] Next, the above-obtained solutions and the following chemicals were mixed in the following compositions to prepare coating solutions for the thermal recording material. ２ Dry weight of 5g / m on fine paper ２ The mixture was coated and dried to prepare a thermosensitive recording paper containing a thermosensitive recording layer of the present invention.

[0076] (Formation of Protective Layer) Next, a protective layer coating solution having the following composition was applied to the heat-sensitive recording layer so that the dry weight was 2 g / m ２ The mixture was coated and dried to prepare a heat-sensitive recording layer with a protective layer: 40% styrene / acrylic acid ester copolymer emulsion 115 parts, 5% bentonite aqueous dispersion 17 parts, 45% styrene-acrylic copolymer aqueous emulsion 44 parts, 39% zinc stearate aqueous dispersion 103 parts, 67% calcium carbonate aqueous dispersion 15 parts

[0077] 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 by a laser diffraction / scattering particle size distribution analyzer LA-950 (manufactured by Horiba, Ltd.) to prepare solution [C], and a comparative thermosensitive recording paper was obtained in the same manner as in Example 1, except that solution [C] was used instead of solution [A] of the thermosensitive recording layer coating solution described in Example 2 above, and mixed in the following composition ratio to prepare a thermosensitive recording material coating solution. Solution [C]: 25 parts bisphenol S (Tokyo Chemical Industry Co., Ltd.), 20 parts 25% aqueous PVA solution, 55 parts water

[0078] [Water Resistance Evaluation Test] Samples of the thermal recording paper obtained in Example 2 and Comparative Example 1 were printed using 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 printed area (colored area) of the samples before and after the test was measured using a colorimeter manufactured by GRETAG-MACBETH, trade name "SpectroEye." 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 7 below. Note that a higher survival rate in this test indicates better water resistance. The survival rate was calculated using the following formula (I): survival rate (%) = [(Macbeth reflection density of the printed area of ​​the sample after the test) / (Macbeth reflection density of the printed area of ​​the sample before the test)] x 100 (I)

[0079]

[0080] As is clear from Table 7 above, Example 2, in which the compound represented by formula (1) above was used as the color-developing compound, had a higher survival rate in the above test than Comparative Example 1, in which bisphenol S, the color-developing compound described in Patent Document 2, was used, and it can be said that the present invention has superior water resistance in the printed area to the prior art.

[0081] [Heat Resistance of Background] The thermal recording paper samples obtained in Example 2 and Comparative Example 1 were kept at 90°C for 1 hour using a constant temperature incubator (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. All color measurements were performed using 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 8 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.

[0082]

[0083] As is clear from Table 8 above, Example 2, in which the compound of the present invention was used as the color-developing compound, showed a smaller change in ISO whiteness in the above test than Comparative Example 1, in which bisphenol S, the color-developing compound described in Patent Document 2, was used, and it can be said that the present invention has superior heat resistance in the background area to the prior art.

[0084] [Test for Plasticizer Resistance of Printed Area] A vinyl chloride film (containing a plasticizer) was wrapped around a glass plate in a single layer. Each thermal recording paper, printed using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd. at an applied energy of 0.34 mJ / dot, was placed on top of the film. A vinyl chloride wrap film was then wrapped around the film in a single layer and the resulting sheet was then stored in a 40°C environment for 2 hours. The Macbeth reflection density of the printed area of ​​each sample before and after the test was measured using a colorimeter manufactured by GRETAG-MACBETH, trade name "SpectroEye." All color measurements were performed using Illuminant C as the light source, ANSI A as the density standard, and a viewing angle of 2 degrees. The remaining rate of the printed area was calculated using the following formula. The higher the remaining rate in this test, the better the plasticizer resistance of the printed area. Residual rate (%)=[(reflection density of printed area after test) / (reflection density of printed area before test)]×100 The results are shown in Table 9 below.

[0085] As is clear from Table 9 above, Example 2, in which the compound of the present invention was used as the color-developing compound, had a higher residual rate in the above test 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 plasticizer resistance in the printed area compared to conventional technology.

[0086] [Oil Resistance Test for Printed Area] Three drops of salad oil were placed on the printed area (color-developing area) of each thermal recording paper, which had been printed with an applied energy of 0.34 mJ / dot using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd., and the paper was then left at 40°C for 1 hour. The Macbeth reflection density of the printed area of ​​each sample was measured before and after the test using a colorimeter manufactured by GRETAG-MACBETH, trade name "SpectroEye." All color measurements were performed using Illuminant C as the light source, ANSI A as the density standard, and a viewing angle of 2 degrees. The print retention rate was calculated using the following formula. The higher the retention rate in this test, the better the oil resistance of the printed area. Retention rate (%) = [(Reflection density of printed area after test) / (Reflection density of printed area before test)] x 100. The results are shown in Table 10 below.

[0087] As is clear from Table 10 above, Example 2, in which the compound of the present invention was used as the color-developing compound, had a higher residual rate in the above test 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 oil resistance in printed areas compared to conventional technology.

[0088] The present invention provides a heat-sensitive recording material that has excellent heat resistance in the background and excellent water resistance, plasticizer resistance, and oil resistance in the printed area, and overcomes the drawback of color fading and loss of colored records under various conditions, thereby enabling the development of a wide range of applications for non-phenolic heat-sensitive recording materials, including food labels.

Claims

1. A heat-sensitive recording material characterized by containing at least one compound represented by the following general formula (1): (In the formula, R １ ~R １０ , R ２１ , and R ２２ 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. In the formula (1), R １ ~R ５ Two or more of R are hydrogen atoms, and ６ ~R １０ 2. The heat-sensitive recording material according to claim 1, wherein two or more of the following are hydrogen atoms:

3. In the formula (1), R ４ and R ５ is a hydrogen atom, and R ９ and R １０ is a hydrogen atom, provided that R １ ~R ３ , R ６ ~R ８ , R ２１ , and R ２２ 2. The heat-sensitive recording material according to claim 1, wherein is as defined above.

4. In the formula (1), R ３ and R ８ are each independently a hydrogen atom or an alkyl group, and R １ , R ２ , R ４ ~R ７ , R ９ , R １０ , R ２１ and R ２２ 2. The heat-sensitive recording material according to claim 1, wherein is a hydrogen atom.

5. A heat-sensitive recording layer comprising the heat-sensitive recording material according to any one of claims 1 to 4.

6. A thermal recording paper or a thermal film comprising the thermal recording layer according to claim 5.

7. A compound represented by the following general formula (2): (In the formula, R １ ~R １０ , R ２１ , and R ２２ 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.

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