Recording materials

Abstract

To provide a recording material excellent in storage stability (water resistance, plasticizer resistance, oil resistance and alcohol resistance) of a printed area.SOLUTION: The recording material contains a compound represented by general formula (1) in the figure and a sensitizer. (In formula (1), R1 represents a C1-4 linear or branched alkyl group or a substituted or unsubstituted C6-14 aryl group; and R2 represents a hydrogen atom or a C1-4 linear or branched alkyl group.) Also provided are a thermal recording layer containing the recording material, and thermal recording paper having the thermal recording layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a recording material excellent in storage stability and color developability of a color-developing recording portion.

Background Art

[0002] Conventionally, many scientific color-developing systems using energy such as heat, pressure, and light are known. Among them, a color-developing system consisting of a two-component color-developing system of a leuco dye, which is a dye precursor, and a developer that develops color when brought into contact with the leuco dye, is widely used in recording materials. For example, a thermosensitive recording material is generally prepared by dispersing a leuco dye and a developer such as a phenolic compound respectively into fine particles, then mixing the two, and adding additives such as a binder, a sensitizer, a filler, and a lubricant thereto to obtain a coating liquid, which is then applied to paper, film, synthetic paper, or the like. It obtains color-developed recording (printing) through a chemical reaction that occurs when one or both of the leuco dye and the developer melt and come into contact upon heating.

[0003] In order to develop color with such a thermosensitive recording material, a thermal printer or the like incorporating a thermal head is used. Compared with other recording methods, the thermosensitive recording method has the following characteristics: (1) no noise is generated during recording, (2) no development or fixing is required, (3) it is maintenance-free, (4) the machine is relatively inexpensive. Due to these characteristics, it is widely used in lottery tickets, facsimile machines, computer outputs, printers for calculators, recorders for medical measurement, automatic ticket vending machines, thermosensitive recording labels, etc. As its applications expand, it is used in various environments, so its color-developed recording is required to have heat resistance, moisture resistance, water resistance, light resistance, oil resistance, alcohol resistance, plastic resistance and the like.

[0004] Generally, color developers containing phenolic hydroxyl groups have high color-developing ability, and among them, many bisphenol compounds have been reported due to their high color intensity, such as 2,2-bis(4-hydroxyphenylpropane) (bisphenol A) shown in Patent Document 1 and 4,4'-dihydroxydiphenylsulfone (bisphenol S) shown in Patent Document 2. However, the use of phenol compounds such as bisphenol A is problematic due to the endocrine problem, and there is a demand for non-phenol color developers that do not contain a phenol structure. Examples of non-phenol color-developing compounds include diphenylurea-based or sulfonylurea color-developing compounds shown in Patent Documents 3 to 6. Furthermore, Patent Documents 7 and 8 describe attempts to combine color developers or add sensitizers to color developers with high storage stability. However, the thermal recording materials described in these documents suffer from a lack of durability under hydrophilic conditions such as water resistance and alcohol resistance, or durability under hydrophobic conditions such as oil resistance and plasticizer resistance, as well as poor color development. This has somewhat limited their range of applications, and there is a strong desire for the development of thermal recording materials with superior color development and storage stability. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent No. 3539375 [Patent Document 2] Japanese Patent Application Publication No. 57-11088 [Patent Document 3] Special Publication No. 2002-532441 [Patent Document 4] International release 2014 / 080615 [Patent Document 5] International release 2017 / 111032 [Patent Document 6] International release 2019 / 044462 [Patent Document 7] Japanese Patent Application Publication No. 09-104178 [Patent Document 8] International release 2022 / 125104 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a recording material with excellent storage stability and color development of the printed portion. [Means for solving the problem]

[0007] The inventors, after diligent research to achieve the above objectives, discovered that the above problems could be solved by using a recording material containing a compound having a specific structure as a color developer and also containing a sensitizer, thus completing the present invention. In this application, "(numerical value 1) to (numerical value 2)" indicates that upper and lower limits are included.

[0008] In other words, the present invention is [1] General formula (1)

[0009] [ka]

[0010] Recording material containing a compound represented by (general formula (1), in which R1 represents a linear or branched alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms; R2 represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms) and an aromatic compound with a melting point of 60 to 200°C.

[0011] [2] General formula (2) below

[0012] [ka]

[0013] In general formula (2), R3 represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, and n represents an integer of 1 to 5. A recording material comprising a compound represented by the above and an aromatic compound having a melting point of 60 to 200°C,

[0014] A thermosensitive recording layer comprising the recording material according to [3][1] or [2], A thermosensitive recording paper comprising the thermosensitive recording layer according to [4][3], and An ink comprising the recording material according to [5][1] or [2], relates to the above. Effects of the Invention

[0015] By combining a sensitizer with the compound represented by general formula (1), it is possible to provide a thermosensitive recording material in which a printed portion has excellent storage stability and excellent color developability. Mode for Carrying Out the Invention

[0016] The present invention will be described in detail. The recording material of the present invention contains the compound represented by the above general formula (1) as a color developer.

[0017] In general formula (1), R1 represents a linear or branched alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms. Specific examples of the alkyl group represented by R1 in general formula (1) include linear methyl group, ethyl group, n-propyl group and n-butyl group, preferably methyl group or ethyl group, and branched isopropyl group, isobutyl group, sec-butyl group and tert-butyl group, preferably isopropyl group.

[0018] The aryl group represented by R1 in general formula (1) is not particularly limited as long as it has 6 to 12 carbon atoms, but an aryl group having 6 to 10 carbon atoms is preferred. Specific examples thereof include a phenyl group and a naphthyl group, and phenyl is preferred.

[0019] The aryl group represented by R1 in general formula (1) may have substituents. Examples of substituents on the aryl group represented by R1 in general formula (1) include linear or branched alkyl groups having 1 to 4 carbon atoms, with methyl groups being preferred. The number of substituents on the aryl group represented by R1 in general formula (1) is not particularly limited as long as it is less than or equal to the number of substituted sites (5 in the case of a phenyl group, and 7 in the case of a naphthyl group). However, when R1 is a phenyl group, the number of substituents (i.e., the number of integers n in general formula (2) described later) is preferably 1 to 3, and more preferably 1. Furthermore, the substitution position of the substituents on the aryl group represented by R1 in general formula (1) is not particularly limited, but when R1 is a phenyl group and there is one substituent, the substitution position is preferably the 2nd, 3rd, or 4th position of the phenyl group, more preferably the 2nd or 4th position, and even more preferably the 4th position.

[0020] In general formula (1), R2 represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. Specific examples and preferred examples of the linear or branched alkyl group having 1 to 4 carbon atoms represented by R2 in general formula (1) are the same as the specific examples and preferred examples of the alkyl group represented by R1 in general formula (1). The substitution position of R2 in general formula (1) is not particularly limited, but it is preferably one of the carbon atoms adjacent to the carbon atom bonded to the nitrogen atom on the benzene ring specified in the central part of general formula (1).

[0021] As the compound represented by general formula (1), a combination of the preferred embodiments of R1 and R2 described above is preferred. That is, as the compound represented by general formula (1), the compound represented by general formula (2) described above is preferred.

[0022] In general formula (2), R3 represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, and n represents an integer from 1 to 5. Specific examples and preferred examples of linear or branched alkyl groups with prime numbers 1 to 4 represented by R3 in general formula (2) are the same as the specific examples and preferred examples of alkyl groups represented by R1 in general formula (1). Specific examples of the alkoxy group represented by R3 in general formula (2) include linear methoxy groups, ethoxy groups, n-propoxy groups, and n-butoxy groups, preferably methoxy or ethoxy groups, and branched isopropoxy groups, isobutoxy groups, sec-butoxy groups, and t-butoxy groups, preferably t-butoxy groups.

[0023] Specific examples of compounds represented by general formula (1) are listed below, but the compounds represented by general formula (1) contained in the color developer of the present invention are not limited to these.

[0024] [Table 1]

[0025] [Table 2]

[0026] [Table 3]

[0027] [Table 4]

[0028] [Table 5]

[0029] [Table 6]

[0030] Next, we will explain the method for producing the compound represented by general formula (1). Compounds represented by general formula (1) can be produced by combining known synthesis methods. An example of a synthesis flow is shown below, but the method for producing compounds represented by general formula (1) is not limited to this synthesis flow. In the synthesis flow below, R1 and R2 have the same meaning as R1 and R2 in general formula (1).

[0031] [ka]

[0032] First, in "STEP 1," intermediate compound 1 represented by formula [1-3] is obtained by reacting 2-nitroaniline represented by formula [1-1] with a sulfonate salt represented by formula [1-2] in the presence or absence of a base. In the following "STEP 2," intermediate compound 2, represented by formula [1-4], is obtained by reducing intermediate compound 1, represented by formula [1-3], which was obtained in STEP 1. Finally, in "STEP 3," the intermediate compound 2 represented by formula [1-4] obtained in STEP 2 is reacted with the diisocyanate compound represented by formula [2-1], either in the presence or absence of a base, to obtain the compound represented by general formula (1).

[0033] Examples of bases that can be optionally used in STEP 1 and 3 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, diisopropylethylamine, pyridine, and dimethylaminopyridine. The amount of these bases used is preferably 1 to 3 times the molar equivalent of the compound represented by formula [1-1].

[0034] The reactions in STEP 1 to 3 are preferably carried out in solution, with the starting materials and intermediates dissolved in a solvent. The solvents that can be used in the reaction are not particularly limited as long as they do not affect the reaction, but examples 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, and diethylene glycol diethyl ether; nitrile compounds such as acetonitrile; ketone compounds such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester compounds such as ethyl acetate and butyl acetate; sulfone compounds such as sulfolane; sulfoxide compounds such as dimethyl sulfoxide; and alcohol compounds such as methanol, ethanol, and isopropyl alcohol. These may be used individually or in combination.

[0035] The reducing agent used in STEP 2 is not particularly limited as long as it does not affect the sulfonyl group, but examples include hydrogen, iron powder, and hydrazine. When using hydrogen or hydrazine, catalysts such as palladium / carbon or iron chloride / carbon may also be used.

[0036] The reaction temperature for SETP 1-3 is typically -78 to 110°C, preferably 0 to 100°C, and the reaction time is typically 10 minutes to 24 hours.

[0037] In the present invention, the sensitizer (thermofusible compound) used is an aromatic compound with a melting point of 60 to 200°C, such as naphthalene derivatives, aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, aromatic ketone derivatives, benzhydrol derivatives, aromatic hydrocarbon compounds, and animal and plant waxes. However, non-aromatic compounds such as synthetic waxes, waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, carbonic acid or oxalic acid diester derivatives may also be used in combination.

[0038] Aromatic waxes include, as naphthalene derivatives, for example, 1-benzyloxynaphthalene (melting point 74°C), 2-benzyloxynaphthalene (melting point 101-104°C), 1-hydroxynaphthoate phenyl ester (melting point 94-96°C), 2,6-diisopropylnaphthalene (melting point 67-70°C), etc.; as aromatic ethers, for example, 1,2-diphenoxyethane (melting point 95-98°C), 1,4-diphenoxybutane, 1,2-bis(3-methylphenoxy)ethane (melting point 96-100°C), 1,2-bis(4-methoxyphenoxy)ethane Examples of aromatic carboxylic acid derivatives include 1,2-bis(3,4-dimethylphenyl)ethane, 1-phenoxy-2-(4-chlorophenoxy)ethane, 1-phenoxy-2-(4-methoxyphenoxy)ethane, 1,2-diphenoxymethylbenzene (melting point 90-100°C), diphenyl glycol, etc.; for example, benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, dibenzyl terephthalate, etc.; for example, phenyl p-toluenesulfonate, phenyl mesitylene, Examples of biphenyl derivatives include 4-methylphenylmesitylene sulfonate, 4-tolylmesitylene sulfonate, etc.; for example, p-benzylbiphenyl (melting point 85-88°C), p-allyloxybiphenyl, etc.; for example, m-terphenyl, etc.; for example, p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide, 4,4'-diallyloxydiphenylsulfone, diphenylsulfone (melting point 125-130°C), 4,4'-diaminodiphenylsulfone, etc.; aromatic compounds Examples of ton derivatives include 4,4'-dimethylbenzophenone and dibenzoylmethane (melting point 77-80°C); examples of benzhydrol derivatives include 2-methylbenzhydrol (melting point 90-93°C) and 1,1-diphenylethanol (melting point 79-82°C); examples of aromatic hydrocarbon compounds include p-acetoluidine; examples of carbonic acid or oxalate diester derivatives include diphenyl carbonate, dibenzyl oxalate (melting point 80-82°C), di(4-chlorobenzyl) oxalate, and di(4-methylbenzyl) oxalate esters;Examples of higher fatty acid anilides include anilide stearate (melting point 94°C) and anilide linoleate.

[0039] Examples of non-aromatic waxes include wood wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax, and polyethylene oxide; examples of higher fatty acids include stearic acid (melting point 67-72°C) and behenic acid (melting point 72-80°C); and examples of higher fatty acid amides include stearic acid amide (melting point 98-102°C), oleic acid amide (melting point 70°C), N-methyl stearate amide, erucic acid amide (melting point 75-85°C), methylol behenic acid amide, methylene bis-stearate amide, and ethylene bis-stearate amide.

[0040] The recording material of the present invention uses an aromatic compound with a melting point of 60 to 200°C. Preferably, the aromatic compound has a melting point of 80 to 150°C. Below 60°C, under high-temperature conditions such as on a car dashboard, areas other than the printed portion may develop color, potentially making the printed material unreadable (background blurring). Above 200°C, the dissolution-promoting effect of the low-melting-point compound diminishes, reducing its contribution to improving color development.

[0041] The color developer of the present invention may be used in combination with other color developers other than the compound represented by general formula (1), as long as it does not impair the effects of the invention. The color developers that can be used in combination are those that are generally used in pressure-sensitive recording paper and thermal recording paper, for example, α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol A or BPA), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4- Hydroxyphenyl)cyclohexane, 4,4'-thiobisphenol, 4,4'-cyclohexylidenediphenol, 2,2'-bis(2,5-dibrom-4-hydroxyphenyl)propane, 4,4'-isopropylidenebis(2-t-butylphenol), 2,2'-methylenebis(4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone , phenolic compounds such as 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-allyloxy-4'-hydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, methyl bis(4-hydroxyphenyl)acetate, butyl bis(4-hydroxyphenyl)acetate, benzyl bis(4-hydroxyphenyl)acetate, 2,4-dihydroxy-2'-methoxybenzanilide, etc., 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, 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or their polyvalent metal salts, N 1 ,N 3Examples include acid amide derivatives such as -di-m-tolyl-5-(N-(m-tolyl)sulfamoyl)isophthalamide, N-(2-(3-phenylureido)phenyl)benzenesulfonamide, 3-(3-phenylureido)phenyl=4-methylbenzenesulfonate, 1,3-diphenylurea, 3-(3-phenylureido)benzenesulfonamide, N-(2-(3-phenylureido)phenyl)acetamide, 3-(3-tosylureido)phenyl=4-methylbenzenesulfonate, and sulfonylurea derivatives such as 4,4'-bis(3-tosylureido)diphenylmethane.

[0042] The recording material of the present invention comprises a compound represented by general formula (1), and may optionally be used in combination with other color developers, sensitizers, color-developing compound binders, preservation enhancers, fillers, and other additives.

[0043] The content of each component in the recording material of the present invention, expressed as a mass ratio of the solid content in the recording material, is typically 1 to 70% by mass, preferably 5 to 50% by mass, for color developers (compounds represented by general formula (1) and / or other color developers); typically 1 to 50% by mass, preferably 5 to 30% by mass, for color-developing compounds; typically 1 to 80% by mass, preferably 5 to 50% by mass; typically 1 to 90% by mass for binders; typically 30% by mass or less for preservation enhancers; typically 80% by mass or less for fillers; and typically 30% by mass or less for other additives (lubricants, surfactants, defoamers, ultraviolet absorbers, etc.).

[0044] The content of the compound represented by general formula (1) in the recording material of the present invention is usually 60% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more. Furthermore, 98% by mass or more is particularly preferred, and 100% by mass is most preferred.

[0045] Furthermore, it is preferable to use 0.5 to 20 parts by mass, preferably 1 to 5 parts by mass, of a color developer containing the compound represented by general formula (1) per 1 part by mass of the color-developing compound.

[0046] The color-developing compound used in the recording material of the present invention is not particularly limited as long as it is commonly used in pressure-sensitive recording paper or thermal recording paper. Examples of color-developing compounds include fluorane compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds, with fluorane compounds being preferred.

[0047] Specific examples of fluorane compounds include 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluorane, and 3-[N-ethyl-N-(3-ethoxypropyl)amino]-6-methyl-7 -Anilinofluorane, 3-(N-ethyl-N-hexylamino)-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-tetrahydrofurylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(p-chloroanilino)fluorane, 3-diethylamino-6-methyl-7-(p-fluoroanilino)fluorane , 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(p-toluidino)fluorane, 3-diethylamino-7-(o-chloroanilino)fluorane, 3-dibutylamino-7-(o-chloroanilino)fluorane, 3-diethylamino-7-(o-fluoroanilino)fluorane, 3-dibutylamino-7-(o-fluoroanilino)fluorane, 3-diethylamino-7-(3,4-dichloroanilino)fluorane, 3-pyro Examples include lysino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-ethoxyethylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-octylfluorane, and 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-phenethylfluorane, with 3-dibutylamino-6-methyl-7-anilinofluorane being preferred.

[0048] 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-dimethylaminoindole-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole-3-yl)phthalide, and 3-(p-dimethylaminophenyl)-3-(2-phenyl Examples include 3,3-(1,2-dimethylindole-3-yl)-5-dimethylaminophthalide, 3,3-(1,2-dimethylindole-3-yl)-6-dimethylaminophthalide, 3,3-(9-ethylcarbazole-3-yl)-5-dimethylaminophthalide, 3,3-(2-phenylindole-3-yl)-5-dimethylaminophthalide, and 3-p-dimethylaminophenyl-3-(1-methylpyrrole-2-yl)-6-dimethylaminophthalide.

[0049] Specific examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho-(3-methoxybenzo)spiropyran, and 1,3,3-trimethyl-6-nitro-8'-methoxyspiro(indoline-2,2'-benzopyran).

[0050] Specific examples of diphenylmethane compounds include N-halophenyl-leucoauramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, and N-2,4,5-trichlorophenylleucoauramine.

[0051] Specific examples of thiazine compounds include benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue.

[0052] Specific examples of lactam compounds include rhodamine B-anilinolactam and rhodamine Bp-chloroanilinolactam.

[0053] Specific examples of fluorene compounds include 3,6-bis(dimethylamino)fluorenespiro(9,3')-6'-dimethylaminophthalide, 3,6-bis(dimethylamino)fluorenespiro(9,3')-6'-pyrrolidinophthalide, and 3-dimethylamino-6-diethylaminofluorenespiro(9,3')-6'-pyrrolidinophthalide.

[0054] These color-developing compounds are used individually or in combination.

[0055] Specific examples of binders preferably used in the heat-sensitive material of the present invention include water-soluble ones such as methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, 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, alkali salts of iso(or diiso)butylene / maleic anhydride copolymers, or (Me Examples include hydrophobic polymer emulsions such as 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 composite particles of colloidal silica and (meth)acrylic resin.

[0056] Specific examples of preservation-enhancing agents that can be used in combination with the 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), and 1-[α-methyl-α-(4'-hydroxy [Ciphenyl)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' -Hindered phenol compounds such as tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenylsulfone, 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'-diglycidyloxydiphenylsulfone, 4-benzyl oxybenzene Examples include epoxy compounds such as xy-4'-(2-methylglycidyloxy)diphenylsulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type epoxy resin, and bisphenol A type epoxy resin; sodium or polyvalent metal salts of N,N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate; and bis(4-ethyleneiminocarbonylaminophenyl)methane.For example, 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] [L]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'-tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl Hindered phenol compounds such as sulfones, 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'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4'-(2-methylglycidyloxy)diphenylsulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, Examples include epoxy compounds such as phenol novolac type epoxy resins and bisphenol A type epoxy resins, sodium or polyvalent metal salts of N,N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate, bis(4-ethyleneiminocarbonylaminophenyl)methane, urea urethane compounds (such as the color-developing compound UU manufactured by Chemipro Chemicals Co., Ltd.), and diphenyl sulfone crosslinked compounds represented by the following formula (6) or mixtures thereof. In formula (6), a is an integer from 0 to 6.

[0057] [ka]

[0058] Specific examples of fillers that can be used in combination with the recording material of 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-formaldehyde resin, and the like.

[0059] Other additives that can be used in combination with the recording material of the present invention include, for example, metal salts of higher fatty acids such as zinc stearate and calcium stearate, which are used for purposes such as preventing thermal head wear and sticking; ultraviolet absorbers such as phenol derivatives, benzophenone compounds and benzotriazole compounds, which are used to impart antioxidant and anti-aging effects; and various surfactants and defoaming agents.

[0060] Next, the method for preparing the recording material and thermal recording paper of the present invention will be described. A color developer, sensitizer, and preferably used color-developing compound containing the compound represented by general formula (1), which is an essential component of the recording material of the present invention, are pulverized and dispersed together with a binder or other additives as needed using a disperser such as a ball mill, attritor, or sand mill to form a dispersion (usually, when pulverization or dispersion is performed wet, water is used as the medium). The dispersions are then mixed together to prepare a coating solution for the recording material, which is then applied to a support such as paper (plain paper, fine paper, coated paper, etc. can be used), a plastic sheet, or synthetic paper at a dry weight of 1 to 20 g / m². 2 By applying the material using a bar coater, blade coater, etc., and drying it, a thermal recording paper having a thermal recording layer containing the recording material of the present invention can be obtained. Furthermore, the term "thermal recording paper" in this specification also includes materials on which a thermal recording layer is provided on a support other than paper.

[0061] If necessary, an intermediate layer may be provided between the thermal recording layer and the support, or an overcoat layer (protective layer) may be provided on the thermal recording layer. The intermediate layer and overcoat layer (protective layer) are prepared, for example, in the same way as the preparation method for the coating solution of the recording material described above, by grinding and dispersing the necessary components for the intermediate layer and overcoat layer together with a binder or other additives used as needed to form a coating solution, and then the dry weight is usually 0.1 to 10 g / m². 2 Apply to the desired consistency and allow to dry to form the desired shape.

[0062] Furthermore, the coating solution (dispersion) of the recording material of the present invention described above can also be incorporated into general writing instrument inks and inkjet inks. For example, writing instrument inks can be produced by mixing the dispersion of the recording material with an aqueous ink, which is appropriately blended with water as a solvent, a water-soluble organic solvent, a thickener, a lubricant, a rust inhibitor, a preservative, or an antibacterial agent depending on the application, or with an oil-based ink, which is appropriately blended with a main solvent such as polypropylene glycol, polybutylene glycol, and polyoxypropylene diglyceryl ether, a resin, a lubricant, a rust inhibitor, a preservative, or an antibacterial agent depending on the application. [Examples]

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by the following examples. In the examples, "parts" means parts by weight, and "%" means percentage by weight.

[0064] Synthesis Example 1 (Synthesis of Compound No. 30 in Table 1 (hereinafter referred to as No. 30)) (Step 1) Synthesis of the compound represented by the following formula (100-4) 420 parts of methyl isobutyl ketone were mixed with 75 parts of 2-nitroaniline (Tokyo Chemical Industry Co., Ltd.) represented by formula (100-1), 129 parts of p-toluenesulfonyl chloride (represented by formula (100-2)), and 110 parts of pyridine (Junsei Chemical Co., Ltd.) represented by formula (100-3). The mixture was stirred at 100°C until the p-toluenesulfonyl chloride was completely reacted. After cooling the reaction mixture to room temperature, it was stirred for 1 hour to precipitate crystals. The precipitate was removed by liquid filtration, and the resulting filtrate was concentrated. Methanol was added to precipitate crystals. The precipitated crystals were collected by filtration, washed with methanol, and dried to obtain 80 parts of the compound represented by formula (100-4) (4-methyl-N-(2-nitrophenyl)benzenesulfonamide) as a yellow solid.

[0065] [ka]

[0066] (Step 2) Synthesis of the compound represented by the following formula (101-3) 500.0 parts methanol, 50.0 parts of the compound obtained in step 1, 7.3 parts activated carbon, and 7.6 parts iron(III) chloride hexahydrate were added and the mixture was heated to reflux temperature. Then, 45.0 parts of hydrazine monohydrate (Tokyo Chemical Industry Co., Ltd.), represented by the following formula (101-1), were added dropwise and the mixture was stirred under reflux for 3 hours. The activated carbon was removed by liquid filtration, and the resulting filtrate was concentrated to precipitate crystals. The precipitated crystals were collected by filtration, washed with a 30% methanol aqueous solution, and dried to obtain 32.0 parts of a pale yellow solid of the compound (N-(2-aminophenyl)-4-methylbenzenesulfonamide), represented by the following formula (101-3).

[0067] [ka]

[0068] 80.0 parts of ethyl acetate were added to 8.0 parts of the compound obtained in step 2, and the mixture was stirred at room temperature. Then, 2.3 parts of 2,4-tolylene diisocyanate (Tokyo Chemical Industry Co., Ltd.), represented by the following formula (102-1), were added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitated crystals were filtered off, washed with ethyl acetate, and dried to obtain 8.0 parts of a white solid of compound (No. 30), represented by the following formula [102-2].

[0069] [ka]

[0070] [Creation of thermal recording material] (Preparation of solution [A]) Using a multi-bead shocker (model: PV1001(S)) manufactured by Yasui Kikai Co., Ltd., No. 30 obtained in Synthesis Example 1 was mixed with the composition shown in Table 7 below, ground for 1 hour, and dispersed to prepare solution [A] of Synthesis Example 1.

[0071] [Table 7]

[0072] The "other ingredients" used in solution [A] are as follows: • 20% PVA aqueous solution: 20% aqueous solution of Gosenex L-3266 (manufactured by Mitsubishi Chemical Corporation) • SF104: Surfinol 104PG-50 (50% propylene glycol solution of Surfinol 104 manufactured by Nisshin Chemical Industry Co., Ltd.)

[0073] (Preparation of solution [B]) Using a sand grinder, a mixture of the following composition was ground and dispersed to a median particle size of 1 μm using a laser diffraction / scattering particle size distribution analyzer LA-950 (manufactured by Horiba, Ltd.) to prepare a dispersion of the chromogenic compound [B]. 2-anilino-6-dibutylamino-3-methylfluorane 35 parts 15% PVA aqueous solution 40 parts Water 25 parts The components used in solution [B] are as follows: 2-Anilino-6-dibutylamino-3-methylfluorane:PSD-290 (manufactured by Nippon Soda Co., Ltd.) • 15% PVA aqueous solution: 15% aqueous solution of Gosenex L-3266 (manufactured by Mitsubishi Chemical Corporation)

[0074] (Preparation of solution [C]) Solution [C] was prepared in the same manner as above, except that No. 30 in Table 7 was replaced with the sensitizer shown in Table 8.

[0075] [Table 8]

[0076] [Examples 1-13] (Preparation of the coating solution for the recording material) The [A] solution, [B] solution, [C-1] to [C-13] solutions and other components obtained above were mixed in the composition shown in Table 9 to prepare a coating solution for the recording material. The components other than [A'] solution and [B] solution were the same as those in the examples.

[0077] [Table 9]

[0078] The "other components" used in the coating solution for the recording material are as follows: • 67% calcium carbonate aqueous dispersion: YCC-FD (manufactured by Yabashi Kogyo Co., Ltd.) • 15% PVA aqueous dispersion: A 15% aqueous dispersion of polyvinyl alcohol (PVA-110, manufactured by Kuraray Co., Ltd.) • 27% St-Zn dispersion: A 27% aqueous dispersion of zinc stearate (manufactured by Go-o Chemical Industry Co., Ltd.)

[0079] (Preparation of thermal recording paper) The coating solution of the recording material obtained in Example 1 was prepared with a basis weight of 50 g / m². 2 The dry weight on high-quality paper is 6.8g / m². 2The thermal recording paper of the present invention was prepared by coating and drying it in such a manner, and its water resistance, plasticizer resistance, oil resistance, and alcohol resistance were evaluated as follows.

[0080] [Comparative Examples 1-8] (Preparation of solution A') In Table 7, except for [Comparative Example 1], solution [A'] was prepared in the same manner, except that No. 30 was replaced with the color developer shown in Table 10.

[0081] [Table 10]

[0082] Prepare a thermal recording material coating solution by mixing solutions [A'-1] to [A'-8], solution [B], and the following chemicals in the composition shown in Table 11, with a basis weight of 50 g / m². 2 The dry weight on high-quality paper is 5.0g / m². 2 The materials were coated and dried to prepare comparative thermal recording paper, and their color development, water resistance, plasticizer resistance, oil resistance, and alcohol resistance were evaluated as follows. The components other than [A'] solution and [B] solution were the same as those in the examples.

[0083] [Table 11]

[0084] (Color development evaluation) Using a thermal printer (TH-M2 / PP) manufactured by Okura Engineering Co., Ltd., printing was performed on the thermal recording paper obtained in Examples 1-13 and Comparative Examples 1-8 with a pulse width of 1.4 msec. The reflectance density of the color-developing area was measured using a colorimeter manufactured by X-Rite, product name "eXact," and the color development performance was evaluated according to the following evaluation criteria. A higher reflectance density indicates superior color development, and evaluation criterion D indicates insufficient performance for practical use, thus limiting its applications. The results are shown in Table 12. • Evaluation criteria A: Reflection density 0.9 or more B: Reflectance between 0.8 and less than 0.9 C: Reflectance between 0.7 and less than 0.8 D: Reflectance less than 0.7

[0085] (Water resistance evaluation) Each thermal recording paper printed using the same method as described in the "Color Development Evaluation" was immersed in water and left for 24 hours, then removed and dried. Using an X-Rite colorimeter, product name "eXact," the reflectance density of the colored area of ​​the thermal recording paper was measured before and after immersion, under the conditions of illuminant C as the light source, status A as the density standard, and a viewing angle of 2 degrees. Remaining percentage (%) = Reflectance after immersion / Reflectance before immersion × 100 The percentage of color remaining in the colored area was calculated using the formula shown, and water resistance was evaluated according to the following evaluation criteria. A higher percentage of color remaining indicates superior water resistance. Evaluation criterion D indicates insufficient performance for practical use, thus limiting its applications. The results are shown in Table 12. • Evaluation criteria A: Survival rate 90% or more B: Survival rate between 85% and less than 90% C: Survival rate 80% or more but less than 85% D: Survival rate less than 80%.

[0086] (Plasticizer resistance evaluation) Each thermal recording paper, printed using the same method as described in the "Color Development Evaluation," was double-wrapped with PVC wrap (product name: Denka Wrap Fresh, manufactured by Denka Polymer Co., Ltd.) on both the recording layer and the back surface. After being left at 40°C for 2.5 hours, the PVC wrap was removed. Using the same method and calculation formula as described in the "Water Resistance Evaluation of Thermal Recording Paper" above, the percentage of color remaining in the colored area before and after being left at 40°C for 2.5 hours was calculated, and the plasticizer resistance was evaluated according to the evaluation criteria below. A higher percentage of remaining plasticizer resistance indicates superior plasticizer resistance. Evaluation criterion D indicates insufficient performance for practical use, thus limiting its applications. The results are shown in Table 12. • Evaluation criteria A: Survival rate 90% or more B: Survival rate between 85% and less than 90% C: Survival rate 80% or more but less than 85% D: Survival rate less than 80%.

[0087] (Oil resistance evaluation) Cottonseed oil (Tokyo Chemical Industries) was applied to the printed area of ​​each thermal recording paper printed using the same method as in the "Color Development Evaluation" described above. After being left at room temperature for 1.5 hours, the cottonseed oil was wiped off. The remaining percentage (%) of the colored area before and after being left at room temperature for 1.5 hours was calculated using the same method and formula as in the "Water Resistance Evaluation of Thermal Recording Paper" described above, and the oil resistance was evaluated according to the evaluation criteria below. A higher remaining percentage indicates better oil resistance, and evaluation criterion D indicates insufficient performance for practical use, thus limiting its applications. The results are shown in Table 12. • Evaluation criteria A: Survival rate 90% or more B: Survival rate between 85% and less than 90% C: Survival rate 80% or more but less than 85% D: Survival rate less than 80%.

[0088] (Alcohol resistance evaluation) Each thermal recording paper, printed using the same method as in the "Color Development Evaluation" described above, was immersed in a 20% ethanol aqueous solution, left at room temperature for 2 hours, and then removed and dried. Using the same method and calculation formula as in the "Water Resistance Evaluation of Thermal Recording Paper" described above, the percentage of color remaining in the colored area before and after being left at room temperature for 2 hours was calculated, and the alcohol resistance was evaluated according to the evaluation criteria below. A higher percentage of remaining color indicates better alcohol resistance, and evaluation criterion D indicates insufficient performance for practical use, thus limiting its applications. The results are shown in Table 12. • Evaluation criteria A: Survival rate 90% or more B: Survival rate between 85% and less than 90% C: Survival rate 80% or more but less than 85% D: Survival rate less than 80%.

[0089] The results of the color development test, water resistance test, plasticizer resistance test, oil resistance test, and alcohol resistance test are summarized in Table 12 below. A rating of D in each property is undesirable in practical use and limits its applications. As is clear from this table, Examples 1 to 13 using the compound of the present invention show a good overall balance in color development and storage stability compared to Comparative Example 1 which does not use a sensitizer and Comparative Examples 2 to 8 which use the compounds described in Patent Documents 2 to 8.

[0090] Table 12

Claims

1. The following general formula (1) 【Chemistry 1】 (In general formula (1), R １ R represents a linear or branched alkyl group with 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group with 6 to 14 carbon atoms. ２ A recording material containing a compound represented by (where represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms) and an aromatic compound with a melting point of 60 to 200°C.

2. The following general formula (2) 【Chemistry 2】 (In general formula (2), R ３ A recording material containing a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, where n is an integer from 1 to 5, and an aromatic compound with a melting point of 60 to 200°C.

3. A thermal recording layer comprising the recording material according to claim 1 or claim 2.

4. A thermal recording paper comprising the thermal recording layer described in claim 3.

5. An ink comprising the recording material according to claim 1 or claim 2.

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