Novel Colorant and Recording Material

Abstract

To provide a recording material that serves as a thermal recording layer of thermal recording paper with its printed part demonstrating superior thermal stability.SOLUTION: The present invention provides a developer represented by the general formula (1) (where R1 is a halogen atom or a C1-8 linear or branched alkoxy group, and one of R2 and R3 is a hydrogen atom while the other is a C3-8 branched alkyl group), a recording material including the developer, a thermal recording layer including the recording material, and thermal recording paper including the thermal recording layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel color former and a recording material containing the color former.

Background Art

[0002] Conventionally, many scientific color development systems using energy such as heat, pressure, and light are known. Among them, a color development system composed of a two-component color development system of a leuco dye which is a dye precursor and a color former that develops color upon contact with the leuco dye is widely used in recording materials. For example, a thermal recording material is generally obtained by dispersing a leuco dye and a color former such as a phenolic compound in fine particle form and then mixing the two, and adding additives such as a binder, a sensitizer, a filler, and a lubricant to the mixture to obtain a coating solution, which is then applied to paper, film, synthetic paper, etc. Color recording (printing) is obtained by a chemical reaction that occurs when one or both of the leuco dye and the color former melt and come into contact upon heating. In order to develop such a thermal recording material, a thermal printer incorporating a thermal head or the like is used. Compared with other recording methods, the thermal recording method has the following characteristics: (1) no noise is generated during recording, (2) there is no need for development and fixing, (3) it is maintenance-free, and (4) the machine is relatively inexpensive. Therefore, it is widely used in the fields of facsimile, computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, and thermal recording type labels.

[0003] In recent years, the uses of recording materials containing a leuco dye and a color former have expanded in the fields of food and beverages as a temperature indicating material and in the fields of toys and writing instruments as a discoloring material by utilizing the reversible reaction between a pigment and a leuco dye. As the usage environment diversifies with the expansion of applications, various environmental resistances are required for the obtained color recordings, such as heat resistance, moisture resistance, water resistance, light resistance, oil resistance, alcohol resistance, and plasticity resistance.

[0004] Generally, color developers having phenolic hydroxyl groups have high color-developing ability. Among them, due to the high color density, many bisphenol-based compounds such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) shown in Patent Document 1 and 4,4'-dihydroxydiphenyl sulfone (bisphenol S) shown in Patent Document 2 have been reported. However, the use of phenolic compounds such as bisphenol A has been a problem due to endocrine issues, and non-phenolic color developers that do not contain a phenol structure are desired. As non-phenolic color developers, for example, diphenylurea-based color developers shown in Patent Document 3 have been reported. However, the diphenylurea-based color developers shown in Patent Document 3 have a drawback that they have lower thermal stability compared to phenolic color developers and the color-developed records fade and disappear only by being exposed to heating for a relatively short time. Therefore, there are certain restrictions on the expansion of their applications, and the development of recording materials with excellent thermal stability is strongly desired.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a recording material in which the printing portion has excellent thermal stability.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventor has found that the above problems can be solved by using a recording material containing a compound having a specific structure as a color developer, and has completed the present invention. That is, the present invention relates to [1] A developer represented by the following general formula (1):

[0008] [Chemical formula]

[0009] (In formula (1), R 1 represents a halogen atom or a linear or branched alkoxy group having 1 to 8 carbon atoms. One of R 2 and R 3 represents a hydrogen atom, and the other represents a branched alkyl group having 3 to 8 carbon atoms.) [2] The developer according to the above item [1], wherein R 1 is a halogen atom or a linear or branched alkoxy group having 1 to 4 carbon atoms, one of R 2 and R 3 is a hydrogen atom, and the other is a branched alkyl group having 3 or 4 carbon atoms. [3] The developer according to the above item [2], wherein R 1 is a halogen atom or a linear or branched alkoxy group having 1 to 3 carbon atoms, one of R 2 and R 3 is a hydrogen atom, and the other is a t-butyl group. [4] A recording material containing the developer according to any one of the above items [1] to [3]. [5] A thermal recording layer containing the recording material according to the above item [4]. [6] A thermal recording paper having the thermal recording layer according to the above item [5], and [7] An ink containing the recording material according to the above item [4]. The present invention relates to the above. [Advantages of the Invention]

[0010] By using the compound represented by the general formula (1) as a developer, a recording material in which the printed portion exhibits high thermal stability can be provided. [Embodiments for Carrying Out the Invention]

[0011] The present invention will be described in detail. The color former of the present invention contains a compound represented by the above general formula (1).

[0012] In formula (1), R 1 represents a halogen atom or a linear or branched alkoxy group having 1 to 8 carbon atoms. R 2 and R 3 one of them represents a hydrogen atom, and the other represents a branched alkyl group having 3 to 8 carbon atoms. Examples of the halogen atom represented by R 1 in formula (1) include a fluorine atom, a chlorine atom, and a bromine atom, and a fluorine atom and a chlorine atom are preferred.

[0013] The alkoxy group represented by R 1 in formula (1) may be linear or branched as long as it has 1 to 8 carbon atoms, and a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, and a t-butoxy group having 1 to 4 carbon atoms are preferred, and a linear or branched alkoxy group having 1 to 3 carbon atoms is more preferred. In addition, in the present specification, for example, the "linear or branched alkoxy group having 1 to 8 carbon atoms" does not include the non-existent "branched alkoxy group having 1 or 2 carbon atoms".

[0014] The branched alkyl group represented by R 2 or R 3 in formula (1) is not particularly limited as long as it has 3 to 8 carbon atoms, but an isopropyl group, an isobutyl group, a sec-butyl group, and a t-butyl group having 3 or 4 carbon atoms are preferred, and a t-butyl group is more preferred.

[0015] As R 1 to R 3 in formula (1), it is particularly preferred that R 1 is a halogen atom or a linear or branched alkoxy group having 1 to 4 carbon atoms, R 2 is a branched alkyl group having 3 or 4 carbon atoms, and R 3 is a hydrogen atom, and R 1is a halogen atom or a linear or branched alkoxy group having 1 to 3 carbon atoms, and R 2 is a t-butyl group, and R 3 is most preferably a hydrogen atom.

[0016] Specific examples of the color former (compound) represented by the following formula (1) are given below, but the color former of the present invention is not limited thereto.

[0017] [Table 1]

[0018] [Table 2]

[0019] Next, the production method of the color former of the present invention will be described. The color former of the present invention can be produced by a method according to the following known production flow (the upper is the production flow of the color former where R 3 is a hydrogen atom, and the lower is the production flow of the color former where R 2 is a hydrogen atom). In the following production flow, R 1 to R 3 are synonymous with R 1 to R 3 in the formula (1).

[0020] [Chemical formula]

[0021] The color former (compound) represented by the above general formula (1-1) can be produced by reacting isocyanates represented by the formula (A) with amines represented by the formula (B-1) in the presence or absence of a base. Further, the color former (compound) represented by the above general formula (1-2) can be produced by reacting isocyanates represented by the formula (A) with amines represented by the formula (B-2) in the presence or absence of a base.

[0022] Examples of the base optionally used in the above production method include inorganic bases such as sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium hydrogen carbonate, potassium carbonate, and cesium carbonate; and organic bases such as triethylamine and diisopropylethylamine. The amount of these bases used is preferably 1 to 3 moles per mole of the isocyanates represented by formula (A).

[0023] The solvent used in the above production method is not particularly limited as long as it does not affect the reaction. 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 and 2-butanone; ester compounds such as ethyl acetate and butyl acetate; sulfone compounds such as sulfolane; and sulfoxide compounds such as dimethyl sulfoxide. These may be used alone or in combination.

[0024] The reaction temperature in the above production method is usually -78 to 100 °C, preferably 0 to 80 °C, and the reaction time is usually 10 minutes to 24 hours.

[0025] The recording material of the present invention contains a color former represented by formula (1), and preferably a color-developing compound, a sensitizer, and a binder, and may further contain a preservative improver, a filler, and other additives as optional components. The content of each component in the recording material of the present invention is in terms of mass ratio in the recording material. The color-forming compound is preferably 1 to 50% by mass, more preferably 5 to 30% by mass; the color developer represented by the general formula (1) is preferably 1 to 70% by mass, more preferably 5 to 50% by mass; the sensitizer is preferably 1 to 80% by mass, and the binder is preferably 1 to 90% by mass. Also, the content of the optional component is that the preservative improver is preferably 30% by mass or less, the filler is preferably 80% by mass or less; other additives (lubricants, surfactants, defoamers, ultraviolet absorbers, etc.) are preferably 30% by mass or less.

[0026] Moreover, it is a more preferred embodiment to use 0.5 to 20 parts by mass of the color developer represented by the general formula (1) with respect to 1 part by mass of the color-forming compound, and it is a particularly preferred embodiment to use 1 to 5 parts by mass. Incidentally, in the recording material of the present invention, a color developer other than the color developer represented by the formula (1) may be used in combination as long as the effects of the invention are not impaired.

[0027] The color-forming compound preferably used in the recording material of the present invention is not particularly limited as long as it is generally used in pressure-sensitive recording paper or thermal recording paper. Examples of the color-forming compound include fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds, etc., and fluoran compounds are preferred.

[0028] Specific examples of the fluoran compound include 3 - diethylamino - 6 - methyl - 7 - anilinofluoran, 3 - dibutylamino - 6 - methyl - 7 - anilinofluoran, 3-(N - methyl - N - cyclohexylamino)-6 - methyl - 7 - anilinofluoran, 3-(N - ethyl - N - isopentylamino)-6 - methyl - 7 - anilinofluoran, 3-(N - ethyl - N - isobutylamino)-6 - methyl - 7 - anilinofluoran, 3-[N - ethyl - N-(3 - ethoxypropyl)amino]-6 - methyl - 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-(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, etc. Among them, 3 - dibutylamino - 6 - methyl - 7 - anilinofluoran is preferred.

[0029] 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, 3-(p-dimethylaminophenyl)-3-(2-phenylindol-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, etc.

[0030] Specific examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho-(3-methoxybenz)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-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenylleucoauramine, etc. Specific examples of thiazine compounds include benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc.

[0031] Specific examples of lactam compounds include rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam, etc. Specific examples of the fluorene-based compounds include 3,6-bis(dimethylamino)fluorene spiro(9,3’)-6’-dimethylaminophthalide, 3,6-bis(dimethylamino)fluorene spiro(9,3’)-6’-pyrrolidinophthalide, 3-dimethylamino-6-diethylamino fluorene spiro(9,3’)-6’-pyrrolidinophthalide, and the like. These coloring compounds are used alone or in admixture.

[0032] Sensitizers (thermofusible compounds) preferably used in the 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, sulfone derivatives, aromatic ketone derivatives, and aromatic hydrocarbon compounds, and the like.

[0033] Examples of waxes include wood rosin, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax, oxidized polyethylene, etc.; examples of higher fatty acids include stearic acid, behenic acid, etc.; examples of higher fatty acid amides include stearic acid amide, oleic acid amide, N-methyl stearic acid amide, erucic acid amide, methylol behenic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, etc.; examples of higher fatty acid anilides include stearic acid anilide, linoleic acid anilide, etc.; examples of naphthalene derivatives include 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, phenyl 1-hydroxynaphthoate, 2,6-diisopropylnaphthalene, etc.; 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, 1-phenoxy-2-(4-methoxyphenoxy)ethane, 1,2-diphenoxymethylbenzene, diphenyl glycol, etc.; examples of aromatic carboxylic acid derivatives include benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, dibenzyl terephthalate, etc.; examples of aromatic sulfonic acid ester derivatives include phenyl p-toluenesulfonate, phenyl mesitylenesulfonate, 4-methylphenyl mesitylenesulfonate, 4-tolyl mesitylenesulfonate, etc.; examples of carbonic acid or oxalic acid diester derivatives include diphenyl carbonate, dibenzyl oxalate, di(4-chlorobenzyl) oxalate, di(4-methylbenzyl) oxalates, etc.; examples of biphenyl derivatives include p-benzylbiphenyl, p-allyloxybiphenyl, etc.; examples of terphenyl derivatives include m-terphenyl, etc.; examples of sulfone derivatives include p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide, 4,4'-diallyloxydiphenyl sulfone, diphenyl sulfone, etc.;Examples of the aromatic ketone derivatives include 4,4'-dimethylbenzophenone, dibenzoylmethane, etc.; examples of the aromatic hydrocarbon compounds include p-acetotoluidine, etc.

[0034] Specific examples of the binder preferably used in the heat-sensitive material of the present invention include methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, 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 copolymer, alkali salts of iso(or diiso)butylene / maleic anhydride copolymer, etc., water-soluble ones or (meth)acrylic acid ester copolymers, styrene / (meth)acrylic acid ester copolymers, polyurethanes, polyester-based polyurethanes, polyether-based polyurethanes, polyvinyl acetate, ethylene / vinyl acetate copolymer, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinylidene chloride, polystyrene, styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid-based copolymer, acrylonitrile / butadiene (NB) copolymer, carboxylated acrylonitrile / butadiene (NB) copolymer, and composite particles of colloidal silica and (meth)acrylic resin, etc., hydrophobic polymer emulsions, etc.

[0035] The developer other than the one represented by the formula (1) that can be used in combination with the recording material of the present invention is not particularly limited as long as it is generally used in pressure-sensitive recording paper or thermal recording paper. Examples include 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'-cyclo-hexylidenediphenol, 2,2'-bis(2,5-dibromo-4-hydroxyphenyl)propane, 4,4'-isopropylidenebis(2-t-butylphenol), 2,2'-methylenebis(4-chlorophenol), 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-methoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 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, phenolic compounds such as 2,4-dihydroxy-2'-methoxybenz anilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acid derivatives, aromatic carboxylic acids, or their polyvalent metal salts, etc.

[0036] Specific examples of the preservative improver 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), 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-tertiary butyl-3-hydroxybenzyl) isocyanurate, 4,4'-thiobis(3-methylphenol), 4,4'-dihydroxy-3,3',5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl sulfone, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane and other hindered phenol compounds, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4'-(2-methylglycidyloxy)diphenyl sulfone, diglycidyl terephthalate, cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin and other epoxy compounds, 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 and the like.For example, hindered phenol compounds such as 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',5,5'-tetramethyldiphenyl sulfone, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane; epoxy compounds such as 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4'-(2-methylglycidyloxy)diphenyl sulfone, diglycidyl terephthalate, cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin; 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, ureaurethane compounds (such as developer UU manufactured by Chemipro Kasei Co., Ltd.), and diphenyl sulfone crosslinked type compounds represented by the following formula (6) or mixtures thereof. In the formula (6), a is an integer from 0 to 6.

[0037] [Chemical formula]

[0038] Specific examples of the filler 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-formalin resin, and the like.

[0039] Other additives that can be used in combination with the recording material of the present invention include, for example, zinc stearate and other higher fatty acid metal salts such as calcium stearate used for the purpose of preventing wear and sticking of the thermal head, phenolic derivatives used to impart an antioxidant effect and an anti-aging effect, ultraviolet absorbers such as benzophenone-based compounds and benzotriazole-based compounds, and various surfactants and defoaming agents.

[0040] Next, the method for preparing the recording material and the thermal recording paper of the present invention will be described. The color former represented by the formula (1), which is an essential component of the recording material of the present invention, and the color-developing compound preferably used are each pulverized and dispersed with a disperser such as a ball mill, an attritor, or a sand mill together with a binder or other additives used as necessary to form a dispersion (usually, when pulverizing and dispersing are carried out wet, water is used as a medium). Then, the respective dispersions are mixed to prepare a coating liquid for the recording material, and on a support such as paper (ordinary paper, high-quality paper, coated paper, etc. can be used), a plastic sheet, or synthetic paper, the dry weight is usually 1 to 20 g / m 2 By coating and drying with a bar coater, a blade coater, etc. so as to obtain the thermal recording paper having a thermal recording layer containing the recording material of the present invention. In addition, the category of "thermal recording paper" in this specification includes those in which a thermal recording layer is provided on a support other than paper.

[0041] If necessary, an intermediate layer may be provided between the heat-sensitive recording layer and the support, or an overcoat layer (protective layer) may be provided on the heat-sensitive recording layer. The intermediate layer and the overcoat layer (protective layer) can be formed, for example, in the same manner as the method for adjusting the coating liquid of the above-described recording material. That is, the components necessary for the intermediate layer and the overcoat layer are pulverized and dispersed together with a binder or other additives used as necessary to form a coating liquid, and then coated and dried so that the dry weight is usually 0.1 to 10 g / m 2 It may be formed by coating and drying to such an extent.

[0042] In addition, the coating liquid (dispersion liquid) of the recording material of the present invention described above can also be contained in general writing instrument inks and inkjet inks. For example, an aqueous ink appropriately blended with a solvent such as water, a water-soluble organic solvent, a thickener, a lubricant, a rust inhibitor, a preservative or an antibacterial agent according to the application, and a main solvent such as polypropylene glycol, polybutylene glycol and polyoxypropylene diglyceryl ether, A writing instrument ink can be prepared by mixing a resin, a lubricant, a rust inhibitor, a preservative or an antibacterial agent, etc., appropriately blended according to the application, and a dispersion liquid of the recording material.

Examples

[0043] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" means parts by mass and "%" means mass%.

[0044] Example 1 (Synthesis of Color Developer of the Present Invention) 7.9 parts of 4-tert-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (100-1) was added to 200.0 parts of methyl isobutyl ketone and stirred at room temperature, and then cooled to 3°C. Next, 8.0 parts of 2-chlorophenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (100-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was filtered off, washed successively with hexane and water, and dried to obtain 11.3 parts of a white solid of a color developer 1 (compound of compound number 1 in Table 1) represented by the following formula (100-3).

[0045] [Chemical formula]

[0046] Example 2 (Synthesis of the Color Developer of the Present Invention) 8.9 parts of 4-tert-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 200.0 parts of methyl isobutyl ketone and stirred at room temperature, and then cooled to 3°C. Next, 8.0 parts of 2-fluorophenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (101-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 12.4 parts of a white solid of a color developer 2 (the compound of Compound No. 2 in Table 1) represented by the following formula (101-3).

[0047] [Chemical formula]

[0048] Example 3 (Synthesis of the Color Developer of the Present Invention) 7.7 parts of 4-tert-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 200.0 parts of acetone and stirred at room temperature. Next, 7.5 parts of 2-methoxyphenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (102-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 10.0 parts of a white solid of a color developer 3 (the compound of Compound No. 4 in Table 1) represented by the following formula (102-3).

[0049] [Chemical formula]

[0050] Example 4 (Synthesis of the Color Developer of the Present Invention) To 200.0 parts of acetone, 7.4 parts of 4-sec-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature. Next, 7.5 parts of 2-methoxyphenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (100-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 9.3 parts of a white solid of a color developer 4 (compound of compound number 13 in Table 1) represented by the following formula (103-3).

[0051]

Chemical formula

[0052] Comparative Example 1 (Synthesis of a comparative color developer) To 200.0 parts of acetone, 10.2 parts of 4-n-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (200-1) was added, and the mixture was stirred at room temperature. Next, 8.0 parts of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (200-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 12.7 parts of a white solid of a comparative color developer 1 represented by the following formula (200-3).

[0053]

Chemical formula

[0054] Comparative Example 2 (Synthesis of a comparative color developer) To 200.0 parts of acetone, 10.2 parts of 4-tert-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature. Next, 8.0 parts of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise, and after stirring at room temperature for 1 hour, 50.0 parts of hexane was added dropwise to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 11.1 parts of a white solid of a comparative color developer 2 represented by the following formula (201-3).

[0055]

Chemical formula

[0056] Comparative Example 3 (Synthesis of a Comparative Color Former) To 200.0 parts of acetone, 8.8 parts of 4-n-hexylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (202-1) was added, and the mixture was stirred at room temperature. Next, 7.5 parts of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 13.7 parts of a white solid of a comparative color former 3 represented by the following formula (202-3).

[0057]

Chemical formula

[0058] Comparative Example 4 (Synthesis of a Comparative Color Former) To 200.0 parts of acetone, 7.4 parts of 4-n-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature. Next, 7.5 parts of 4-chlorophenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (203-2) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 13.2 parts of a white solid of a comparative color former 4 represented by the following formula (203-3).

[0059]

Chemical formula

[0060] Comparative Example 5 (Synthesis of a Comparative Color Former) To 200.0 parts of acetone, 8.4 parts of p-anisidine (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula (204-1) was added, and the mixture was stirred at room temperature. Next, 8.0 parts of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise, and the mixture was stirred at room temperature for 1 hour to precipitate crystals. The precipitate was separated by filtration, washed successively with hexane and water, and dried to obtain 13.5 parts of a white solid of a comparative color former 5 represented by the following formula (204-3).

[0061]

Chem.

[0062] Examples 5 to 8 and Comparative Examples 6 to 10 (Adjustment of Recording Material and Preparation of Thermal Recording Paper Having a Thermal Recording Layer Containing the Recording Material) (Adjustment of Solution [A]) Using a multi-bead shocker (Model: PV1001(S)) manufactured by Yasui Kikai Co., Ltd., each color former and other components obtained in Examples 1 to 4 and Comparative Examples 1 to 5 were pulverized and dispersed for 1 hour with the compositions shown in Table 3 to prepare Solution [A] of A-1 to A-9, respectively. The "other components" used in Solution [A] are as follows. · Aqueous PVA solution: 20% aqueous solution of Gosenex L-3266 (manufactured by Mitsubishi Chemical Corporation) · SF104: 50% propylene glycol solution of Surfynol 104PG-50 (Surfynol 104 manufactured by Nissin Chemical Industry Co., Ltd.)

[0063]

Table 3

[0064] (Adjustment of Solution [B]) Using a sand grinder, a mixture having the following composition was pulverized and dispersed so that the median particle size measured by a laser diffraction / scattering type particle size distribution measuring apparatus LA-950 (manufactured by Horiba, Ltd.) became 1 μm to prepare Solution [B] of the color-forming compound. 35 parts of 2-anilino-6-dibutylamino-3-methylfluorane 40 parts of aqueous PVA solution 25 parts of water Each component used in Solution [B] is as follows. · 2-anilino-6-dibutylamino-3-methylfluorane: PSD-290 (manufactured by Nippon Soda Co., Ltd.) · Aqueous PVA solution: 15% aqueous solution of Gosenex L-3266 (manufactured by Mitsubishi Chemical Corporation)

[0065] (Adjustment of Coating Liquid for Recording Material) The [A] liquid, [B] liquid and other components obtained above were mixed in the composition shown in Table 4 to prepare a coating liquid for the recording material. The "other components" used in the coating liquid for the recording material are as follows. CaCO3 dispersion: 67% aqueous dispersion of calcium carbonate (YCC-FD, manufactured by Yabashi Kogyo Co., Ltd.) PVA aqueous solution: 15% aqueous solution of polyvinyl alcohol (PVA-110, manufactured by Kuraray Co., Ltd.) StZn dispersion: 37% aqueous dispersion of zinc stearate (manufactured by Gohou Chemical Industry Co., Ltd.)

[0066]

Table 4

[0067] (Production of Thermal Recording Paper) The coating liquids of the recording materials obtained in Examples 5 to 8 and Comparative Examples 6 to 10 were each applied onto high-quality paper with a basis weight of 50 g / m 2 and dried so that the weight during drying was 5 g / m 2 to produce the thermal recording papers of the present invention and for comparison.

[0068] (Evaluation of Heat Resistance of Thermal Recording Paper) Each thermal recording paper obtained using the coating liquids of the recording materials in Examples 5 to 8 and Comparative Examples 6 to 10 was printed using a thermal printer (TH-M2 / PP) manufactured by Ookura Engineering Co., Ltd. at a pulse width of 1.4 msec, and the printed matter was heated at 60°C for 24 hours. The reflection density of the colored part of the sample before and after heating was measured using a colorimeter manufactured by X-Rite, product name "eXact", and the residual rate was calculated by the following formula (I). The color measurement was performed under the conditions of using illuminant C as the light source, the density standard was status A, and the viewing angle was 2 degrees. The results are shown in Table 5. The higher the residual rate in Table 5, the better the heat resistance. Formula (I); Residual rate (%) = (Reflection density of colored part after heating) / (Reflection density of colored part before heating) × 100

[0069]

Table 5

[0070] From the results of Table 5 above, it can be seen that the thermal recording paper of the example using the recording material containing the color former with the specific structure of the present invention is superior in heat resistance of the printed portion (color-developed portion) to the thermal recording paper of the comparative example using the recording material containing the color former (the color former described in Patent Document 3) of the comparative example.

Claims

Claim 1 A color former represented by the following general formula (1): 【Chemical 1】 (In formula (1), R １ represents a halogen atom or a linear or branched alkoxy group having 1 to 8 carbon atoms. One of R ２ and R ３ represents a hydrogen atom, and the other represents a branched alkyl group having 3 to 8 carbon atoms.) Claim 2 Claim 3 R １ is a halogen atom or a linear or branched alkoxy group having 1 to 4 carbon atoms, R ２ and R ３ wherein one of them is a hydrogen atom and the other is a branched alkyl group having 3 or 4 carbon atoms, the developer according to claim 1. Claim 4 R １ is a halogen atom or a linear or branched alkoxy group having 1 to 3 carbon atoms, R ２ and R ３ wherein one of them is a hydrogen atom and the other is a t-butyl group, the color former according to claim 2. A recording material containing the color former according to any one of Claims 1 to 3. Claim 5 A heat-sensitive recording layer containing the recording material according to Claim 4. Claim 6 A heat-sensitive recording paper having the heat-sensitive recording layer according to Claim 5. Claim 7 An ink containing the recording material according to Claim 4. ​

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