Fluorane dimer compounds and recording materials using the same

Abstract

To provide a recording material with excellent performances such as base whiteness, storage stability, and image fastness, suitable for producing vivid magenta-colored images.SOLUTION: The present invention provides a fluoran dimer compound represented by general formula (1). (In formula (1), R1 and R2 independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. R1 and R2 may bond together to form an aliphatic ring or a heterocyclic ring. A represents an alkylene group, a carbonyl group or an oxygen atom, and n represents an integer of 0-1).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fluoran dimer compound and a recording material containing the same. More specifically, a color-forming compound having an electron-donating property that develops a magenta color (true red), i.e., a fluoran dimer compound and an electron-accepting developer react with a photo-thermal conversion agent that generates heat by near-infrared light of a thermal head or a laser, and the present invention relates to a fluoran dimer compound suitable for a recording material capable of recording an image or data.

Background Art

[0002] In recent years, from the viewpoint of global environmental conservation, the development of rewritable recording material technology has been remarkable. As a reversible recording medium capable of reversibly recording and erasing information by heat or light, the spread of various prepaid cards, point cards, credit cards, IC cards, etc. has been progressing, and furthermore, the use of reversible recording media has been studied even in the field of displays. Parallel to this, full-colorization has been progressing from the viewpoint of design. Among the three primary colors, a leuco dye that develops a clear magenta color (true red) and has excellent durability before and after coloring is required.

[0003] Patent Document 1 discloses a fluoran compound that develops a magenta color (true red) as a heat-sensitive recording paper capable of two-color development recording. However, since the light resistance before and after coloring is low and the color changes, it poses a problem as a heat-sensitive recording paper capable of two-color development recording, and thus improvement is required. Patent Document 2 discloses a fluoran compound that develops a magenta color (true red) that develops a red color as a reversible multicolor recording medium. However, like Patent Document 1, the light resistance before and after coloring is low and the color changes, which poses a problem as a reversible multicolor recording medium, and thus improvement is required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The object of the present invention is to provide a full-color reversible thermal recording material containing a fluorane dimer compound that develops a high concentration of magenta (crimson) color and exhibits high lightfastness with no color change before and after development. [Means for solving the problem]

[0006] As a result of investigating the above-mentioned problems, the present inventors found that these problems could be solved by including a fluorane dimer compound with a specific structure in the color-developing composition, and thus completed the present invention.

[0007] In other words, the present invention is (i) Fluoran dimer compounds represented by general formula (1) TIFF0007850040000001.tif50157

[0008] (In formula (1), R1 and R2 operate independently. hydrogen atom, This represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. R1 and R2 may bond to each other to form an aliphatic ring or a heterocycle. A represents an alkylene group, a carbonyl group, or an oxygen atom, and n represents an integer between 0 and 1.

[0009] (ii) A fluorane dimer compound of (i) in which R1 is an alkyl group having 1 to 12 carbon atoms. (iii) In a recording material that utilizes the reaction between an electron-donating leuco dye and an electron-accepting developer, the recording material is characterized by containing a fluoran dimer compound described in any one of (i) to (ii) as the electron-donating leuco dye. (iv) The recording material according to (iii), wherein the recording material is a heat-sensitive recording material.

Effects of the Invention

[0010] The fluoran dimer compound of the present invention is colorless or almost colorless in the normal state, but upon reaction (interaction) with a developer, it develops a distinct magenta color (true red), and the developed color image has high light resistance and does not deteriorate. Therefore, it is useful as a magenta (true red) color-developing material for full-color heat-sensitive recording materials.

Modes for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail. The fluoran dimer compound of the present invention is characterized by having at least one kind in a recording material that utilizes the reaction between an electron-donating leuco dye and an electron-accepting developer. First, the fluoran dimer compound will be described below.

[0012] [Fluoran Dimer Compound] The fluoran dimer compound of the present invention is represented by the following general formula (1). TIFF0007850040000002.tif50157

[0013] (In formula (1), R1 and R2 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. R1 and R2 may be bonded to each other to form an aliphatic ring or a heterocyclic ring. A represents an alkylene group, a carbonyl group, or an oxygen atom, and n represents an integer of 0 to 1.)

[0014] R1 to R2 are more preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cyclic alkyl group having 5 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 25 carbon atoms, even more preferably, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 19 carbon atoms, a substituted or unsubstituted aryl group having 6 to 11 carbon atoms, Most preferably, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms can be mentioned.

[0015] Examples of these substituents are shown below. Examples of unsubstituted alkyl groups include linear or branched unsubstituted alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, 1-methylpentyl group, 4-methyl-2-pentyl group, 2-ethylbutyl group, n-heptyl group, 1-methylhexyl group, n-octyl group, 1-methylheptyl group, 2-ethylhexyl group, etc.

[0016] Examples of substituted alkyl groups include for example, alkyl groups having an alkyloxy group or an alkenyloxy group such as methoxymethyl group, ethoxymethyl group, n-butoxymethyl group, n-hexyloxymethyl group, (2-ethylbutyloxy)methyl group, 2-(4'-pentenyloxy)ethyl group, etc., for example, alkyl groups having an aralkyloxy group such as benzyloxymethyl group, 2-(benzyloxymethoxy)ethyl group, etc., for example, alkyl groups having an aryloxy group such as phenyloxymethyl group, 4-chlorophenyloxymethyl group, 4-(2'-phenyloxyethoxy)butyl group, etc. For example, alkyl groups having a thioalkyl group such as n-butylthiomethyl group and 2-n-octylthioethyl group, Examples include alkyl groups having halogen atoms such as fluoromethyl, trifluoromethyl, perfluoroethyl, 4-fluorocyclohexyl, dichloromethyl, 4-chlorocyclohexyl, and 7-chloroheptyl groups.

[0017] As substituted or unsubstituted cyclic alkyl groups: For example, cyclopentyl group, cyclohexyl group, 4-methylcyclohexyl group, 3-methylcyclohexyl group, 2-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-isopropylcyclohexyl group, 3,3,5-trimethylcyclohexyl group, 4-dimethylaminocyclohexyl group, 4-butylcyclohexyl group, 4-tert-butylcyclohexyl group, 4-sec-butylcyclohexyl group, 4-trifluoromethylcyclohexyl group, 3-trifluoromethylcyclohexyl group, 4-Amylcyclohexyl group,

[0018] As for substituted or unsubstituted aralkyl groups, For example, aralkyl groups that are unsubstituted or have alkyl groups, such as benzyl group, α-methylbenzyl group, phenethyl group, α-methylphenethyl group, α,α-dimethylbenzyl group, α,α-dimethylphenethyl group, 4-methylphenethyl group, 4-methylbenzyl group, and 4-isopropylbenzyl group. For example, aralkyl groups having an allyl group or aralkyl group such as 4-benzylbenzyl group, 4-phenethylbenzyl group, 4-phenylbenzyl group, For example, aralkyl groups having substituted oxy groups such as 4-methoxybenzyl group, 4-n-tetradecyloxybenzyl group, 4-n-heptadecyloxybenzyl group, 3,4-dimethoxybenzyl group, 4-methoxymethylbenzyl group, 4-vinyloxymethylbenzyl group, 4-benzyloxybenzyl group, and 4-phenethyloxybenzyl group. For example, aralkyl groups having halogen atoms such as 4-fluorobenzyl group, 3-chlorobenzyl group, and 3,4-dichlorobenzyl group, Furthermore, examples include 2-furfuryl group, diphenylmethyl group, 1-naphthylmethyl group, and 2-naphthylmethyl group.

[0019] As substituted or unsubstituted aryl groups: For example, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2-n-propylphenyl group, 3-n-propylphenyl group, 4-n-propylphenyl group, 4-isopropylphenyl group, 3-n-butylphenyl group, 4-n-butylphenyl group, 4-isobutylphenyl group, 4-tert-butylphenyl group, 2-n-pentylphenyl group, 3-n-pentylphenyl group, 4-n-pentylphenyl group, 4-isopentylphenyl group, 4-tert-pentylphenyl group, 3-n-hexylphenyl group, 4-n-hexylphenyl group, 4-cyclohexylphenyl group, 3-n-heptylphenyl group, 4-n-heptylphenyl group, 2-n- Cutylphenyl group, 3-n-octylphenyl group, 4-n-octylphenyl group, 3-n-nonylphenyl group, 4-n-nonylphenyl group, 3-n-decylphenyl group, 4-n-decylphenyl group, 4-n-undecylphenyl group, 3-n-dodecylphenyl group, 4-n-dodecylphenyl group, 4-n-tetradecylphenyl group, 2,3-dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 3,4,5-trimethylphenyl group, 2,3,5,6-tetramethylphenyl group, 5-indanyl group, 1,2,3,4-tetrahydro-5-naphthyl group, 1,2,3,4-tetrahydro-6-naphthyl group,

[0020] 2-Methoxyphenyl group, 3-Methoxyphenyl group, 4-Methoxyphenyl group, 3-Ethoxyphenyl group, 4-Ethoxyphenyl group, 4-n-Propoxyphenyl group, 4-Isopropoxyphenyl group, 2-n-Butoxyphenyl group, 3-n-Butoxyphenyl group, 4-n-Butoxyphenyl group, 4-Isobutoxyphenyl group, 4-n-Pentyloxyphenyl group, 2-n-Hexyloxyphenyl group, 3-n-Hexyloxyphenyl group, 4-n-Heptyloxyphenyl group, 3-n-Octyloxyphenyl group, 4-n-Octyl Oxyphenyl group, 4-n-nonyloxyphenyl group, 4-n-decyloxyphenyl group, 4-n-undecyloxyphenyl group, 4-n-dodecyloxyphenyl group, 4-n-tetradecyloxyphenyl group, 2,3-dimethoxyphenyl group, 2,4-dimethoxyphenyl group, 2,5-dimethoxyphenyl group, 3,4-dimethoxyphenyl group, 3,5-dimethoxyphenyl group, 3,5-diethoxyphenyl group, 2-methoxy-4-methylphenyl group, 2-methoxy-5-methylphenyl group, 2-methyl-4-methoxyphenyl group, 3-methyl-4-methoxyphenyl group, 3-methyl-5-methoxyphenyl group, 2-Fluorophenyl group, 3-Fluorophenyl group, 4-Fluorophenyl group, 2-Chlorophenyl group, 3-Chlorophenyl group, 4-Chlorophenyl group, 4-Bromophenyl group, 3-Trifluoromethylphenyl group, 4-Trifluoromethylphenyl group, 3-Trifluoromethyloxyphenyl group, 4-Trifluoromethyloxyphenyl group, 2,4-Difluorophenyl group, 2,4-Dichlorophenyl group, 3,4-Difluorophenyl group, 3,4-Dichlorophenyl group, 3,5-Difluorophenyl group, 3,5-Dichlorophenyl group, 3,4,5-Trifluorophenyl group, 2-Methyl-4-Chlorophenyl group, 2-Chloro-4-methylphenyl group, 3-Chloro-4-methylphenyl group, 2-Chloro-4- Methoxyphenyl group, 3-methoxy-4-fluorophenyl group, 3-methoxy-4-chlorophenyl group, 3-fluoro-4-methoxyphenyl group, 2,3,4,5,6-pentafluorophenyl group, 4-phenylphenyl group, 3-phenylphenyl group, 4-(4'-methylphenyl)phenyl group, 4-(4'-methoxyphenyl)phenyl group, 1-naphthyl group, 2-naphthyl group, 4-methyl-1-naphthyl group, 4-ethoxy-1-naphthyl group, 6-n-butyl-2-naphthyl group, 6-methoxy-2-naphthyl group, 7-ethoxy-2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 9-anthracenyl group, 2-tetracerenyl group, 2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 9,9-di-n-propyl-2-fluorenyl group, 2-furyl group, 5-n-butyl-2-furyl group, 5-n-hexyl-2-furyl group, 5-n-octyl-2-furyl group, 2-thienyl group, 5-n-propyl-2-thienyl group, 5-n-butyl-2-thienyl group, 5-n-hexyl-2-thienyl group, 5-n-octyl-2-thienyl group, 5-n-decyl-2-thienyl group, 5-n-tridecyl-2-thienyl group Examples of substituted or unsubstituted aryl groups include 5-phenyl-2-thienyl group, 5-(2'-thienyl)-2-thienyl group, 5-(5'-n-butyl-2'-thienyl)-2-thienyl group, 5-(5'-n-hexyl-2'-thienyl)-2-thienyl group, 5-(5'-n-decyl-2'-thienyl)-2-thienyl group, 3-thienyl group, 2-pyridyl group, 3-pyridyl group, and 4-pyridyl group.

[0021] A concrete example of a case where R1 and R2 are linked to each other to form a heteroalgebra is: Examples include pyrrolidino group, piperidino group, 4-methylpiperidino group, 4-isopropylpiperidino group, pyrrolidino group, and 3-methylpyrrolidino group.

[0022] In general formula (1), A is preferably an oxygen atom, a carbonyl group, or an alkylene group having 1 to 6 carbon atoms. A is more preferably an oxygen atom, a carbonyl group, or an alkylene group having 1 to 3 carbon atoms. Examples of alkylene groups include methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl, propane-1,1-diyl, propane-2,2-diyl, butane-1,4-diyl, butane-2,3-diyl, 1,1,2,2-tetramethylethane-1,2-diyl, butane-1,2-diyl, pentane-1,5-diyl, pentane-1,2-diyl, 2,4-diethylpentane-1,5-diyl, 3-methylpentane-1,5-diyl, cyclopentane-1,3-diyl, hexane-1,6-diyl, hexane-1,4-diyl, hexane-2,4-diyl, cyclohexane-1,4-diyl, cyclohexane-1,3-diyl, and cyclohexane-1,2-diyl. Alkylene groups having 1 to 6 carbon atoms are particularly preferred, and alkylene groups having 1 to 3 carbon atoms are more preferred. n is preferably an integer between 0 and 1.

[0023] Specific examples of the fluorane dimer compound of general formula (1) contained in the recording material of the present invention are shown in the table below, but the invention is not limited to these examples. TIFF0007850040000003.tif249170

[0024] TIFF0007850040000004.tif250170

[0025] TIFF0007850040000005.tif250170

[0026] TIFF0007850040000006.tif251170

[0027] TIFF0007850040000007.tif250170

[0028] TIFF0007850040000008.tif248167

[0029] TIFF0007850040000009.tif249169

[0030] TIFF0007850040000010.tif249170

[0031] TIFF0007850040000011.tif250170

[0032] TIFF0007850040000012.tif250169

[0033] The fluorane dimer compound of general formula (1) of the present invention can be produced, for example, by reacting a compound represented by general formula (2) and a compound represented by general formula (3) at a temperature of 0 to 100°C for several tens of hours in the presence of a dehydrating condensation agent, followed by treatment with alkali.

[0034] TIFF0007850040000013.tif35146 (In formula (2), R1~R2, A, and n represent the same values ​​as R1~R2, A, and n in general formula (1))

[0035] TIFF0007850040000014.tif17141 (In formula (3), R represents a hydrogen atom or a lower alkyl group)

[0036] As dehydrating condensation agents, concentrated sulfuric acid, fuming sulfuric acid, polyphosphate, and phosphorus pentoxide can be used, but concentrated sulfuric acid is particularly preferred. When concentrated sulfuric acid is used as a dehydrating condensation agent, the reaction temperature is preferably in the range of 0 to 80°C.

[0037] Alkaline treatment involves reacting the two raw materials mentioned above in the presence of a dehydrating condensation agent, and then placing the resulting product under alkaline conditions at a constant temperature for a certain period of time. Sodium hydroxide, potassium hydroxide, sodium carbonate, etc., can be used as the alkali, but sodium hydroxide is particularly preferred, and it is preferable to use it as an aqueous solution. The temperature for alkali treatment is 0 to 100°C, preferably 50 to 100°C, but generally the higher the temperature, the more efficiently the treatment proceeds. The amount of alkali used is preferably such that the pH of the treatment solution becomes 9 or higher. The reaction product treated with alkali is purified by extraction with an organic solvent. Alternatively, the organic solvent may be present during the alkali treatment. Benzene, toluene, xylene, chlorobenzene, etc., can be used as organic solvents, but toluene is usually preferred. Methanol, ethanol, n-propanol, and isopropanol may be used in combination when precipitating the target product from the organic solvent.

[0038] Recording materials composed of an electron-donating color-developing compound that produces a magenta (crimson) color, i.e., the fluorane dimer compound of the present invention, and an electron-accepting color developer, include thermal recording materials that react and produce color using a photoconverter such as a thermal head or laser light as a heat source, and pressure-sensitive recording materials that react and produce color due to the pressure of a pen, etc.

[0039] The reason why the color images produced by recording materials containing the fluorane dimer compound of the present invention exhibit excellent lightfastness is not entirely clear. However, it is thought that, for example, the dye becomes excited by light and enters an activated state that undergoes a photobleaching reaction, but durability is improved by rapidly deactivating the excited state back to the ground state. The fluorane dimer compound of the present invention has a structure in which two fluorane derivatives are linked at A in general formula (1), so it is thought that the dye molecules become dye particles, i.e., an associated state, and relaxation back to the ground state is promoted. Furthermore, by forming a dimer compound, the solubility in oils and plasticizers is reduced compared to general fluorane compounds, resulting in color images with superior oil and plasticizer resistance.

[0040] [Thermal recording material] Thermal recording materials can be manufactured by various known methods disclosed, for example, in Japanese Patent Publication No. 45-14039. Generally, a leuco dye, a developer, and a sensitizer are dispersed in an aqueous solution of a water-soluble polymer such as polyvinyl alcohol using an attritor, sand mill, etc., so that the particle size of the agents is several microns or less. The sensitizer may be added to either the leuco dye or the developer, or both, and dispersed simultaneously. Alternatively, a eutectic mixture with the leuco dye or developer may be prepared in advance and dispersed. These dispersions are mixed, and pigments, binders, waxes, metal soaps, antioxidants, ultraviolet absorbers, etc., are added as needed to obtain a thermal coating solution. The obtained thermal coating solution is applied to a support such as fine paper, synthetic paper, or plastic film, and smoothness is imparted by calendering to obtain thermal recording paper. The thermal coating solution may also be applied to a support having an undercoat layer of plastic pigment or an insulating material such as silica, if necessary, to improve color development. Furthermore, to provide water resistance and chemical resistance as needed, a topcoat layer of a water-soluble polymer aqueous solution or the like may be applied to the thermal recording layer.

[0041] Various phenolic compounds can be used as color developers for thermal recording paper. Specific examples include bisphenol A, 2,2-bis(p-hydroxyphenyl)-4-methylpentane, 1,1-bis(p-hydroxyphenyl)cyclohexane, bisphenol S, 4-hydroxy-4'-isopropoxydiphenylsulfone, 3,3-diallyl-4,4'-dihydroxydiphenylsulfone, 1,5-bis(p-hydroxyphenylmercapto)-3-oxapentane, benzyl p-hydroxybenzoate, tetrabromobisphenol A, and tetrabromobisphenol S. Bisphenol A is particularly preferred.

[0042] Examples of sensitizers include p-benzylbiphenyl, metaterphenyl, 2-benzyloxynaphthalene, 1,4-dibenzyloxynaphthalene, benzyl oxalate, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, 1,2-diphenoxyethane, 1,2-m-toluoxyethane, 1,2-di-p-toluoxyethane, 1,4-diphenoxyethane, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, and benzyl terephthalate. In particular, p-benzylbiphenyl, metaterphenyl, 2-benzyloxynaphthalene, di-p-methylbenzyl oxalate, and 1,2-m-toluoxyethane are preferred. Organic and inorganic pigments can be used as pigments. Preferred examples include calcium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, amorphous silica, urea-formaldehyde resin powder, polyethylene resin powder, and the like.

[0043] As binders, water-soluble polymers and water-insoluble polymers can be used. Preferred examples of water-soluble polymers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, styrene-maleic anhydride copolymer hydrolysate, isobutylene-maleic anhydride copolymer hydrolysate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and polyacrylamide. Examples of water-insoluble polymers include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, and vinyl acetate emulsion. Preferred examples of waxes include paraffin wax, carboxy-modified paraffin wax, and polyethylene wax. As metal soaps, higher fatty acid metal salts are used. Preferred examples include zinc stearate, calcium stearate, and aluminum stearate. Hindered phenols are used as antioxidants. Benzophenone-based and benzotriazole-based UV absorbers are used as UV absorbers.

[0044] In addition, rewritable recording materials can also be mentioned as examples of rewritable thermal recording materials. Rewritable recording materials consist of a paper or synthetic resin film support on which a recording layer is formed, comprising a leuco dye, a smear-decreasing agent or long-chain developer (a compound having both a group that develops color and a group that reduces color in the same molecule upon the action of heat), and a binder. On the surface, a protective layer for improving durability, a UV protective layer, and a protective layer for wear resistance are added as needed. When using a symmetric color-reducing agent, the lactone ring of the leuco dye is cleaved and color develops when it comes into contact with a color-developing group by controlling the thermal energy. Conversely, when it comes into contact with a color-reducing group, the lactone ring closes and the color disappears. When using a long-chain color developer, heating it above its melting point causes it to melt and come into contact with the leuco dye, resulting in color development. Slow cooling then causes separation and crystallization of the leuco dye and color developer, leading to decolorization. However, rapid cooling allows the color developer to aggregate regularly while maintaining its bond with the leuco dye, preserving the colored state. Furthermore, heating it beyond the colored state breaks down the aggregated structure of the colored state, and at temperatures below the color development temperature, the color developer becomes a stable crystalline state on its own, separating from the leuco dye and decolorizing.

[0045] Examples of leuco dyes that can be used include phthalide compounds, azaphthalide compounds, diazaphthalide compounds, and fluorane compounds. Examples of discriminant color reducers include amphoteric compounds having at least one phenolic hydroxyl group and / or carboxyl group, and having an amino group as a functional group or as part of a salt compound, or salts or complex salts of a compound having at least one phenolic hydroxyl group and / or carboxyl group with an aliphatic amine. Examples include aliphatic amines, aminobenzoic acids, hydroxyamino acids, or ester compounds thereof. Examples of long-chain color developers include compounds having a group that develops color for leuco dyes, such as a phenolic hydroxyl group or a carboxyl group, and a group that controls the cohesive force between molecules, such as a group linked to a long-chain hydrocarbon group. [Examples]

[0046] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0047] [Example 1] Production of specific compound (1) 67 g of 98% sulfuric acid was mixed with 12.5 g of compound (A) in small increments at temperatures below 25°C. After dissolution, 6.3 g of compound (B) was added at 10-20°C. The mixture was stirred at room temperature for 1 hour, then heated to 40-50°C and stirred for 20 hours. The reaction mixture was then drained into 700 g of ice water, and the precipitated material was filtered off. The resulting precipitate was refluxed with 300 mL of toluene and 40 g of 30% sodium hydroxide aqueous solution under stirring for 1 hour. The toluene layer was then separated and washed with hot water. The toluene solution was concentrated under reduced pressure, and 200 mL of isopropanol was added to the residue. The mixture was stirred under reflux for 1 hour and then cooled. The precipitate was filtered off, washed with 50 mL of isopropanol, and dried. 13.9 g of the compound (specific example compound (1)) with the following structural formula was obtained as a pale reddish-white powder. Thermal decomposition temperature (TG-5%); 331.3℃ Thermogravimetric thermal analysis was performed, and the temperature at which the weight decreased by 5% was defined as the thermal decomposition temperature (TG-5%). The same method was used thereafter. The obtained compound was confirmed to be the target compound based on the analysis results below. TIFF0007850040000015.tif58170·ESI-Mass: 841(M+H) + • Elemental analysis values: Measured values ​​(C: 79.96%, H: 5.23%, N: 3.36%); Theoretical values ​​(C: 79.98%, H: 5.27%, N: 3.33%)

[0048] [Example 2] Production of specific compound (2) Except for using 14.7g of compound (C) instead of 12.5g of compound (A) in Example 1, 16.5g of compound (2) with the following structural formula was obtained as a pale yellowish-white powder in the same manner as in Example 1. Thermal decomposition temperature (TG-5%); 357.1℃ The obtained compound was confirmed to be the target compound based on the analysis results below. TIFF0007850040000016.tif58170·ESI-Mass: 953(M+H) + • Elemental analysis values: Measured values ​​(C: 80.51%, H: 6.28%, N: 2.97%); Theoretical values ​​(C: 80.65%, H: 6.34%, N: 2.94%)

[0049] [Example 3] Production of specific compound (3) Except for using 15.9g of compound (D) instead of 12.5g of compound (A) in Example 1, 15.4g of compound (3) with the following structural formula was obtained as a light brownish-white powder in the same manner as in Example 1. Thermal decomposition temperature (TG-5%); 331.7℃ The obtained compound was confirmed to be the target compound based on the analysis results below. TIFF0007850040000017.tif58170·ESI-Mass: 1009(M+H) + • Elemental analysis values: Measured values ​​(C: 80.87%, H: 6.69%, N: 2.85%); Theoretical values ​​(C: 80.92%, H: 6.79%, N: 2.78%)

[0050] [Example 4] Production of specific compound (21) Except for using 15.1g of compound (E) instead of 12.5g of compound (A) in Example 1, 17.5g of compound (21) with the following structural formula was obtained as a pale pinkish-white powder in the same manner as in Example 1. Thermal decomposition temperature (TG-5%); 331.4℃ The obtained compound was confirmed to be the target compound based on the analysis results below. TIFF0007850040000018.tif46170·ESI-Mass: 969(M+H) + • Elemental analysis values: Measured values ​​(C: 79.19%, H: 6.17%, N: 2.93%); Theoretical values ​​(C: 79.31%, H: 6.24%, N: 2.89%)

[0051] [Example 5] Production of specific compound (39) Except for using 15.3g of compound (F) instead of 12.5g of compound (A) in Example 1, 13.5g of compound (39) with the following structural formula was obtained as a pale yellow powder in the same manner as in Example 1. Thermal decomposition temperature (TG-5%); 330.4℃ The obtained compound was confirmed to be the target compound based on the analysis results below. TIFF0007850040000019.tif53170·ESI-Mass: 981(M+H) + • Elemental analysis values: Measured values ​​(C: 79.52%, H: 6.13%, N: 2.88%); Theoretical values ​​(C: 79.57%, H: 6.16%, N: 2.86%)

[0052] [Example 6] Production of specific compound (60) Except for using 15.5g of compound (H) instead of 12.5g of compound (A) in Example 1, 12.9g of compound (60) with the following structural formula was obtained as a pale yellowish-white powder in the same manner as in Example 1. Thermal decomposition temperature (TG-5%); 359.1℃ The obtained compound was confirmed to be the target compound based on the analysis results below. • ESI-Mass: 991 (M+H) + • Elemental analysis values: Measured values ​​(C: 71.21%, H: 4.43%, N: 2.87%); Theoretical values ​​(C: 71.51%, H: 4.48%, N: 2.83%)

[0053] [Example 7] Manufacturing of thermal recording material 5 g of specific compound (1) prepared in Example 1 was ground together with 45 g of a 2.5% polyvinyl alcohol aqueous solution using a sand mill to obtain an average particle size of 1 micron, and a dispersion was prepared. On the other hand, 10 g of bisphenol A and 10 g of parabenzyl biphenyl were ground together with 80 g of a 2.5% polyvinyl alcohol aqueous solution using a sand mill to obtain an average particle size of 3 microns, and a dispersion was prepared. After mixing the two dispersions prepared in this way, 30 g of a 50% calcium carbonate dispersion and a 30% paraffin wax dispersion were added and thoroughly mixed to prepare a heat-sensitive coating solution. The basis weight of the heat-sensitive coating solution prepared in this way was 50 g / m². 2 High-quality paper with a solid content coating amount of 5g / m² 2 The material was applied in this manner, and after drying, it was calendered to achieve a Beck smoothness of 400-500 seconds on the thermal recording surface, thereby producing a white thermal recording material.

[0054] [Example 8] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of specific compound (2) prepared in Example 2 was used instead of 5 g of specific compound (1) used in Example 7.

[0055] [Example 9] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of specific compound (3) prepared in Example 3 was used instead of 5 g of specific compound (1) used in Example 7.

[0056] [Example 10] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of specific compound (21) prepared in Example 4 was used instead of 5 g of specific compound (1) used in Example 7.

[0057] [Example 11] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of specific compound (39) prepared in Example 5 was used instead of 5 g of specific compound (1) used in Example 7.

[0058] [Example 12] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of specific compound (60) prepared in Example 6 was used instead of 5 g of specific compound (1) used in Example 7.

[0059] [Comparative Example 1] Manufacturing of thermal recording material A white thermal recording material was prepared in the same manner as in Example 7, except that 5 g of Comparative Example Compound (I) was used instead of 5 g of Specific Example Compound (1) used in Example 7. TIFF0007850040000021.tif42127

[0060] [Quality performance testing of thermal recording materials] Surface whiteness and surface stability tests, and color image stability tests of the thermal recording materials prepared in Examples 7-12 and Comparative Example 1. Measurement of scalp lightfastness: After irradiating a thermal recording material with a 20,000 lux fluorescent lamp for 72 hours, the scalp coloring density (OD value) was measured using a reflectance densitometer RD-914.

[0061] [Table 1]

[0062] Scalp whiteness: A lower number indicates a higher degree of whiteness. Scalp storage stability: A smaller value after each test indicates higher scalp stability. Next, the thermal paper prepared in Examples 7-12 and Comparative Examples 1-2 was printed using a TH-PMD printer (manufactured by Okura Electric) with a pulse width of 0.95 ms, and the colored image density (OD value) was measured using a Macbeth RD-914. Stability testing was performed according to the following method. Measurement of image humidity and heat resistance: After exposing a color image to 50°C and 90%RH for 72 hours, the image density (OD value) was measured using a reflectance densitometer RD-914. Image heat resistance measurement: After exposing a color image to 60°C and 20% RH for 72 hours, the image density (OD value) was measured using a reflectance densitometer RD-914. Image lightfastness measurement: After irradiating a color image with a 20,000 lux fluorescent lamp for 72 hours, the image density (OD value) was measured using a reflectance densitometer RD-914. The image robustness of each image was expressed by the following formula.

[0063]

number

[0064] These results are shown in Table 2. [Quality performance testing of thermal recording materials] [Table 2] [Industrial applicability]

[0065] The recording material using the fluorane dimer compound of the present invention exhibits excellent properties in terms of background whiteness, storage stability, and image fastness, and produces vivid magenta-colored images, making it extremely useful as a colorant for full-color thermal recording materials.

Claims

1. A fluorane dimer compound represented by general formula (1). (In formula (1), R １ , R ２ Each is independent hydrogen atom, This represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. R １ and R ２ These elements may also bond to each other to form aliphatic rings or heterocycles. (A represents an alkylene group, a carbonyl group, or an oxygen atom, and n represents an integer between 0 and 1.)

2. R １ The fluorane dimer compound according to claim 1, wherein is an alkyl group having 1 to 12 carbon atoms.

3. A recording material that utilizes the reaction between an electron-donating leuco dye and an electron-accepting color developer, characterized in that the electron-donating leuco dye contains the fluorane dimer compound described in any one of claims 1 to 2.

4. The recording material according to claim 3, wherein the recording material is a thermal recording material.

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