JPH02668A - Imidazole dye excellent in spectral absorption characteristic and the like - Google Patents

Abstract

PURPOSE:A cyan dye small in pH dependency, not requiring any mordant, having absorption characteristics preferable as a cyan colorant, and excellent light resistance, and suitable for image media in, e.g., photography, thermal transfer, ink jet, printing, etc., comprising an imidazole compound of a specified formula. CONSTITUTION:An imidazole compound of formula I [wherein R1 and R2 are each H, a (substituted) alkyl, R1 and R2 may be bonded together to form a five- or six-membered ring, R3-R6 are each H, a halogen a (substituted) alkyl, a (substituted) alkoxy, or an acylamino; R7 is a monovalent organic group; n is 0-5; and A is an organic group bonded to the imidazole ring through a C, N, O or S atom], e.g., a compound of formula II. A compound of formula I can be synthesized by oxidatively coupling a p-phenylenediamine compound of formula III (wherein R7, A and m are as defined above) with a coupler in the presence of an oxidizing agent.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a novel imidazole dye useful for color image formation, filter use, etc.

[Conventional technology]

British patents 1 and 5 show that diphenylimidazoles form pigments through oxidative coupling with aminophenols.
No. 45,507. These diphenylimidazoles are useful as photographic couplers, and it has been shown that dyes oxidatively coupled with aminophenols can be mordanted with quaternary ammonium mordants to produce images with good light resistance. However, the color tone of oxidatively coupled dyes with aminophenol is highly dependent on pH, and the absorption wavelength λmax becomes significantly shorter at neutral pH. Therefore, when used as an image, the presence of a quaternary mordant is essential. It is. Therefore, in systems where these mordants do not exist, the light absorption λmax of these dyes is at the edge of the visible light range, and various color reproduction methods using subtractive color methods such as photography, thermal transfer, inkjet, and printing are difficult to reproduce. It cannot be used as a cyan dye in image forming means. As a result of various studies, the present inventors replaced the amine phenol with a specific para-phenylene diamine compound, and found that an organic compound bonded to the imidazole ring at the 2-position via a carbon atom, nitrogen atom, oxygen atom, or sulfur atom. By using the cyan dye as a cyan dye, a compound suitable as a cyan dye in the above-mentioned image forming means can be obtained, which has less pH dependence, does not require a mordant, has more preferable spectral absorption characteristics as a cyan dye, and has excellent heat resistance. The present inventors have discovered that the present invention is possible.

[Purpose of the invention]

The purpose of the present invention is to provide photographic, thermal transfer, and ink cyanide dyes with less pH dependence, no need for mordant, more preferable absorption characteristics as a cyan dye, and excellent light resistance.
An object of the present invention is to provide a cyan dye suitable for image media such as printing.

[Structure of the invention]

The above objects of the present invention are achieved in the dyes shown below. An imidazole dye characterized by being represented by the following CI). one-forming CI) represents a group or a substituted alkyl group, and R and R2 may be bonded to each other to form a 5- or 6-membered ring. R1,
R5 and R6 are each a hydrogen atom, a halogen atom,
represents an alkyl group, a substituted alkyl group, an alkoxy group, a substituted alkoxy group, or an acylamino group, R7 represents a monovalent organic group, m represents an integer of 0 to 5, and when m is 2 or more, multiple R2 are They can be the same or different. A represents an organic group bonded to the imidazole ring via a carbon atom, nitrogen atom, oxygen atom or sulfur atom. In one form CI), R and R2 are preferably hydrogen atoms, alkyl groups and substituted alkyl groups such as hydroxyalkyl, alkoxyalkyl, alkoxyalkoxyalkyl and alkylsulfonamidoalkyl groups. Examples of these groups include alkyl groups having 1 to 18 carbon atoms such as methyl, ethyl, furoyl, isopropyl, 5ec-butyl, butyl, isobutyl, t-butyl, octyl, dodecyl, octadecyl, cyclohexyl, hydroquinethyl, etc. , methoxybutyl, ethoxyethyl, methoxyethoxyethyl, ethoxyethoxyethyl, β-methanesulfonamidoethyl, and other substituted alkyl groups. Examples of the 5-membered ring or 6-membered ring formed by combining R1 and R2 include groups such as pyrrolidino, piperidino, piperazino, and morpholino. R1, R5 and R6 may be the same or different, preferably a hydrogen atom, a halogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group,
These include an alkylsulfonamide alkyl group, an alkoxy group, and the like. Examples of these include atoms or groups such as chlorine, bromine, methyl, ethyl, hydroxymethyl, hydroxyethyl, methoxyethyl, methanesulfonamidoethyl, methquine, ethoxy, acetamide, and the like. Preferred examples of the monovalent organic group represented by R7 include a halogen atom (preferably fluorine, chlorine, and bromine), an ano group, a nitro group, a carboxyl group, an optionally substituted alkyl group, an alkoxy group, and an alkyl group. Amide group, arylamide group, alkylsulfonamide group, arylsulfonamide group, carbamoyl group, sulfamoyl group, dialkylcarbamoylamino group, dialkylsulf. Moylamino group; each optionally substituted arylcarbamoylaminocarbonylamino group, imido group, alkylamido group/yl group, alkylsulfamoyl group, arylcarbamoyl group, arylsulfamoyl group, alkoxycarbonyl group, alkoxysulfonyl group Groups such as groups and the like can be mentioned. Among these, it is particularly preferable for the cyan dye to have a hydrogen-bonding group at the position ortho to the bonding position of the phenyl group at the 4-position of the imidazole ring to the imidazole ring in -formation CI) from the viewpoint of absorption wavelength. Examples of the hydrogen-bonding group include an amide group, a carbamoylamino group, a sulfamoylamino group, a sulfamoylamino group, and preferable substituents include an optionally substituted alkylamido group and an optionally substituted aryl group. Amide group (preferably substituted or unsubstituted benzamide group)
, an optionally substituted alkylsulfonamide group, an optionally substituted arylsulfonamide group, a dialkylcarbamoylamino group, a dialkylsulfamo.f
Examples include ruamino group. A is an organic group bonded to the imidazole ring via a carbon atom, nitrogen atom, oxygen atom or sulfur atom. Organic groups via carbon atoms include alkyl groups (for example, methyl, i-propyl, t-butyl, trifluoromethyl, benzyl, 3-(4-aminophenyl)propyl, allyl, 2-dodecyloxyethyl, 3 -phenoxyfurovir, 2-hexylsulfonylethyl, 3-C4-
C4-dodenyloxybenzene)sulfonamidophenyl]propyl, ■-methyl-2-((2-year-old ctyloxy-5-t-octylphenyl)sulfonamidophenyl]ethyl, ■-methyl-2-(2-year-old ctyloxy/-
5-(2-octyloxy-5-t-octylphenylsulfonamide) phenylsulfonamide]ethyl, 2
-(2-octyloxy-5-(2-octyloxy-
5-L-octylphenylsulfonamide) phenylsulfonamide]ethyl, etc.), heterocyclic groups (e.g., 4-pyridyl, 2-benzimidazolyl, etc.), cyano group, carboxyl group, acyl group, carbamoyl group, alkoxycarbonyl group, aryl Examples include oxycarbonyl group. Examples of organic groups via a cognition atom include acylamino groups (e.g., acetamide, benzamide, 2.4-di-monoamylphenoxyacetamide, 2.4-dichloropensamide, etc.), alkoxycarbonylamine groups (e.g., methoxy carbonylamino, propoquinecarbonylamino, t-butoxycarbonylamino, etc.), aryloxycarbonylamino groups (e.g., phenoxycarbonylamino), sulfonamide groups (e.g., methanesulfonamide, octanesulfonamide, benzenesulfonamide, 4-dodecyl oxybenzenesulfonamide, etc.), anilino groups (e.g., phenylamino, 2-chloroanilino, 2-chloro-4-tetradecanamidoanilino, etc.), ureido groups (e.g., N-methylureido, N
-butylureido, N-phenylureido, NN-dibutylureido, etc.), sulfamoylamino groups (e.g.
N,N-diethylsulfamoylamino, N-phenylsulfamoylamino, etc.), amino groups (e.g., unsubstituted amino, N-methylamino, N,N-diethylamino, etc.), heterocyclic groups (e.g., 3.5- dimethyl l-pyrazolyl, 2,6-dimethylmorpholino, etc.). Examples of organic groups via an oxygen atom include alkoxy groups (e.g., methoxy, ethoxy, i-propoxy, butquine,
2,2.2-trifluoroethoxy, 3,3.3-trifluoropropoxy, 2-chloroethoxy, 2-cyanoethoxy, 2-butanesulfonylethoxy, etc.) arylamide group (e.g., phenoxy, 4-methoxyphenoxy, 2.4-dichlorophenoxy, 4(2-ethylhexaneamido)phenoxy, etc.), silyloxy groups (e.g., trimethylsilyloxy, dimethylphenylsilyloxy, dimethyl-t-butylsilyloxy, etc.), heterocyclic oxy groups (e.g., tetrahydro pyranyloxy, 3
-pyridyloxy, 2-(1,3-benzimidazolyl)oxy, etc.). Examples of organic groups via a sulfur atom include alkylthio groups (for example, methylthio, ethylthio, butylthio, 3-(4
-aminophenyl) furovirthio, hexasubylthio,
Benzylthio, 4-aminobenzylthio, 3- (4-
(4-dodecyloxybenzene)sulfonamidophenyl]propylthio, 4-(2-butoxy-5-t-octylphenylsulfonamido)benzylthio, etc.), arylthio groups (e.g., phenylthio, 2-su7tylthio, 2.5- dichlorophenylthio, 4-dodecylphenylthio, 2-butoxy-5-t-octylphenylthio, etc.), heterocyclic thio groups (e.g., 2-pyridylthio, 2-
(1,3-benzoxasilyl)thio group, 1-hexadecyl1.2,3.4-tetrazolyl-5thio group, 1-(
3-N-octadecylcarbamoyl)phenyl-1,2
, 3,4-tetrazolyl-5-thio, etc.). To explain in more detail the monovalent organic group represented by R7, examples of unsubstituted alkyl groups include methyl, ethyl,
Straight chain or branched alkyl groups having 1 to 22 carbon atoms are preferred, such as 5eC-butyl, t-octyl, dodecyl, etc., and substituted alkyl groups include hydroxy-substituted alkyl groups, such as hydroxyethyl, and methoxyethyl. , methoxyethoxyethyl and the like are preferred. Examples of unsubstituted alkokyne groups include methoxy, ethoxy, n-butoxy, 5ec-butoxy, dodecyloquine, octadecyloxy, etc. having 1 to 1 carbon atoms.
22 straight chain or branched alkoxy groups are preferred, and the substituted alkoxy group is preferably an alkoxy-substituted alkoxy group represented by methquine]-oxy and the like. The unsubstituted alkylamide group is preferably an amide group of an alkane having 1 to 22 carbon atoms, such as acetamide, propionamide, pentanamide, laurylamide, stearylamide, etc., and the substituted alkylamide group is preferably 2.4- D-L-amylphenoxyacetamide,
Preferred are phenoxy-substituted alkylamide groups such as 2-(m-hentadecylphenoxy)butanamide, and halogen-substituted alkylamide groups such as chloroacetamide, trifluoroacetamide, and perfluorobutanamide. Examples of the arylamide group include unsubstituted arylamide groups such as benzamide and naphthamide, alkoxy-substituted benzamide groups such as 0-tetradecaoxybenzamide, ■-laurylamide benzamide, m-(2-(
2,4-di-t-amylphenoxy)hexanamide)
Amide- and sulfonamide-substituted benzamides represented by benzamide, 0-hexadecanesulfonamide benzamide, and the like. -A halogen-substituted benzamide group represented by chlorobenzamide, perfluorobenzamide, etc. is preferred. The alkylsulfonamide group has 1 carbon atom and is represented by methanesulfonamide, ethanesulfonamide, butanesulfonamide, hexadecanesulfonamide, etc.
-22 alkane sulfonamide groups are preferred. Examples of arylsulfonamides include unsubstituted arylamide groups such as benzenesulfonamide and naphthalenesulfonamide, as well as p-toluenesulfonamide, xylenesulfonamide, dodecylbenzenesulfonamide, and p-dodecyloxybenzenesulfonamide. An alkyl-substituted benzenesulfonamide group and an alkoxy-substituted benzenesulfonamide group are preferred as the substituted benzenesulfonamide group. Further, as the alkyl group of the dialkylcarbamoylamino group and the dialkylsulfamoylamino group, an alkyl group having 1 to 8 carbon atoms is preferable, and methyl, ethyl, propyl, and butyl each having 1 to 4 carbon atoms are representative and preferable. . In addition, as the arylcarbamoylamino group, unsubstituted phenylcarbamoylamino groups such as phenylcarbamoylamino, p-cyanophenylcarbamoylamino and p-cyanophenylcarbamoylamino
A halogen-substituted phenylcarbamoyl group represented by -chlorophenylcarbamoylamino is preferable as the substituted phenylcarbamoyl group. The alkyl of the alkyloxycarbonylamino group has 1 to 1 carbon atoms, such as methyl, ethyl, butyl, dodecyl, etc.
An unsubstituted alkyl group of 22 is preferable, and the imide group is preferably succinimide, phthalimide, or an alkyl substituted product thereof. The alkyl of the alkylcarbamoyl group and alkylsulfamoyl group has 1 to 2 carbon atoms, such as butyl, dodecyl, etc.
Alkylcarbamoyl groups and alkylsulfamoyl groups with unsubstituted alkyl groups such as the alkyl group in 2, and γ
- Substituted alkylcarbamoyl group or substituted alkylsulfamoyl group having a phenoxy-substituted alkyl group such as -(2,4-di-t-amylphenoquine)butyl, an alkoxy-substituted alkyl group such as n-dodecyloxypropyl, etc. Groups are preferred. Arylcarbamoyl and arylsulfamoyl groups include unsubstituted arylcarbamoyl groups such as phenylcarbamoyl and phenylsulfamoyl, unsubstituted arylsulfamoyl groups, phenylcarbamoyl groups and phenylsulfamoyl substituted with alkyl groups and halogen atoms. A substituted phenylcarbamoyl group and a substituted phenylsulfamoyl group represented by the following groups are preferred. In addition, carbon atoms represented by methoxy, ethoxy, butquine, etc. as alkoxycarbonyl groups and alkoxysulfonyl groups that may be substituted, respectively, and alkoxy groups of alkoxycarbonyl groups and alkoxysulfonyl groups that may be substituted, respectively. number 1~2
2 is preferably an unsubstituted alkoxy group. Representative examples of imidazole dyes of the present invention are listed below. CH. cioy(1) oHs SO7Nt12 0C1211□. C.O. Q Q C0゜N CI. , C0 C11゜C5H++(t) C,O++(t) rH7 General formula [■] The imidazole dye represented by the general formula (1) is a coupler represented by the following -formation CI+) and the following -formation [■]
It can be synthesized by oxidative coupling of a p-phenylenediamine developing agent represented by the formula in the presence of an oxidizing agent. General formula [) (Here, R7, 8 and m are the general formula [■
] This coupling reaction is Preferably, the reaction is carried out under basic conditions, and the reaction medium may be an organic solvent, an aqueous organic solvent, or an aqueous solution. Further, the oxidizing agent may be any one having a potential capable of oxidizing p-phenylenediamine, whether organic or inorganic. Examples of the oxidizing agent include silver halide, hydrogen peroxide, manganese dioxide, potassium persulfate, Inorganic oxidizing agents such as oxygen,
Furthermore, various organic oxidizing agents such as NBS and chloramine T can be used. The cyan dye of the present invention can be obtained by oxidative coupling of an imidasol coupler and p-phenylene diamines as described above. Typical synthesis examples are shown below. Synthesis Example 1 (Synthesis of Compound Example (4)) o-(α-(2,4-di-monoamylphenoxy)β-
Megulbutanamide)-α-bromoacetophenone 1
Suspend 3.3g in 100mQ of acetonitrile,
-dimethylpyrazole-1-lupoxamidine 6.9g
was added and stirred at room temperature for 1 hour. The solvent was distilled off, and the residue was extracted with ethyl acetate and treated with a silica gel column to obtain an amorphous intermediate. Yield 3.3g0 Synthesis of dye 3.3g of the above intermediate was dissolved in 300a+Q of ethyl acetate, 300mQ of 10% potassium carbonate aqueous solution was added, and while stirring at room temperature, 4-amino-3-methyl-N-ethyl-N
(β-methanesulfonamidoethyl)aniline sulfate 1
Added 0g. Next, add 10% red blood salt aqueous solution 70roQ.
It dripped in time. After completion of the dropwise addition, the reaction was allowed to proceed at room temperature for 1 hour. After discarding the aqueous layer and washing with water twice, the solvent was distilled off. /
Power gel column (developing solvent is ethyl acetate:hexane = 1
= 3) to obtain an amorphous solid. Yield 2.2
g0 Synthesis Example 2 (Synthesis of Compound Example (10)) 3 g of the intermediate synthesized in Synthesis Example 1 was added to 100 m of chloroform.
(Dissolved in 2, N-chlorosuccinimide (NC3) 1
g was added thereto, and the mixture was stirred at room temperature for 15 hours. After distilling off the solvent,
Ethyl acetate and water were added and washed, and the organic layer was dried over magnesium sulfate. The solvent was distilled off and hexane was added directly to the residue to solidify it. An intermediate was obtained by purification using a gel ram. Yield: 2.2g. Synthesis of dye Dissolve 2.2 g of the above compound in 200 m of ethyl acetate (2), add 200 m of 10% potassium carbonate aqueous solution (2, and dissolve 4-
6 g of amino N-ethyl-N-(β-hydroxyethyl)aniline sulfate was added. The rest was treated in the same manner as in Synthesis Example 1 to obtain an amorphous solid. Yield 0.8g. Synthesis Example 3 (Synthesis of Compound Example (5)) 9.5 g of o-(α-(2,4-di-monoamylphenoxy)hexanamide)-α-bromoacetophenone was added to 50 mL of chloroform. 6 g of acetamidine was added thereto, and the mixture was heated at 45°C for 3 hours. Distill the solvent and ace)
When the mixture was dissolved in nitrile 20 mC and concentrated hydrochloric acid 1IIIQ was added dropwise, a solid was precipitated. Yield: 1.4 g Synthesis of Dye The desired product was obtained by carrying out the same reaction using 1.4 g of the above compound instead of the intermediate in Synthesis Example 1. Yield 0.5g
. Synthesis Example 4 (Synthesis of Compound Example (30)) 0-(α-(2,4-di-1-amylphenoquine)β-
methylbutanamide) α-bromoaceto7enone lO,
6 g was suspended in 100 mQ of acetonitrile, and 12.9 g of S hexadenyl isothiourea was added. Next, add 30m+2 of dimedylformamide and heat at 60°C for 5 minutes. Pour the reaction solution into 500 mQ of water, and add 200 mQ of ethyl acetate.
After extraction with α and drying with red sea bream sulfate, the solvent was distilled off under reduced pressure. A paste-like intermediate was obtained by purification with a silica gel column (developing solution: ethyl acetate:hexane=1:6). Collection fiLO-3g. Synthesis of Dye 2.5 g of an amorphous solid was obtained by carrying out the same process as in Synthesis Example 1 except that 3.0 g of the above compound was used. Synthesis Example 5 (Synthesis of Compound Example (28)) o-(α-(2,4-di) of Synthesis Example 4

[-amylphenoxy)-β-methylbutanamide)-0-ethoxycarbonylamino-σ- in place of α-bromoacetophenone
The same procedure was performed except that 5.7 g of bromoacetophenone was used to obtain 1.5 g of the desired product. The imidazole dye of the present invention uses a coupler represented by the above-mentioned -formation (If) as a cyan coupler used in silver halide color photographic light-sensitive materials, and p-F22 represented by the above-mentioned -formation [■]. A cyan image is obtained by developing with a color developing solution containing a cyan diamine color developing agent, and coupling the coupler with the p-p-fluorinated diamine developing agent oxidized by exposed silver halide. It is particularly useful as a photographic cyan dye. At this time, the coupler is normally contained in the photographic light-sensitive material, but it can also be used in an external color development method in which the coupler is dissolved together with a color developing agent in the developer. The imidazole dye of the present invention can also be used as a filter dye for photography, and
No. 8-18169, No. 58-205798, No. 58-
It is also useful as a cyan dye for images in thermal transfer processes, ink transfer processes, color electrophotography, printing, etc. as shown in No. 219086. In order to improve the stability of the dye of the present invention against light or heat, known stabilizers can be used in combination. Such stabilizers include, for example, U.S. Pat. No. 3,935,016
hydroquinone derivatives described in U.S. Pat. No. 4,254,216 and JP-A-55-21004; Phenol derivatives, British Patent Publication No. 2,077.45
Spiroindane derivatives and methylenedioxybenzene derivatives described in U.S. Pat. No. 5 J and U.S. Pat. No. 2,062,888, U.S. Pat.
No. 00, No. 3574, No. 627, No. 3,573,05
No. 0, JP-A-51-152225, JP-A No. 53-2032
Taloman derivatives, spirochroman derivatives and coumaran derivatives described in No. 7 and No. 53-17729,
JP 55-6321, British Patent No. 1.347556, British Patent Publication No. 2,066.975 and Japanese Patent Publication No. 1983
Hydroquinone heptanoether derivatives and p-aminophenol derivatives described in No.-12337, Japanese Patent Publication No. 4
Examples thereof include bisphenol derivatives described in US Pat. No. 8-31625 and US Pat. No. 3,700.455, and metal complexes such as those described in US Pat. No. 4.245.018. Effects of the Invention The dye of the present invention is useful as a cyan dye for color image formation using a subtractive color method, and can also be used as a filter dye for solid-state image pickup tubes, color LCD televisions, etc. by mixing with a yellow or magenta dye to produce a green color image. Or it can be used as a blue filter. At least in the above applications, the dye of the present invention has an extremely good hue as a cyan dye, and has a molar extinction coefficient (
ε) and high heat resistance. Compared to known phenolic and naphtholic indoaniline cyan dyes, the dye of the present invention has a sharp tail on the short wavelength side of the spectral transmittance curve, and therefore has a large subabsorption in the line region. It has a significantly reduced width, less irregular absorption, and a molar absorption coefficient in the red region that is more than twice as large.It also has good light fastness and heat resistance, making it suitable for color photography based on the subtractive color method. The dyes of the present invention have improved pH dependence compared to known dyes formed by oxidative coupling of imidazoles and aminophenols. , there is no shortening of the neutral absorption wavelength λmax in the absence of a quaternary mordant. [Example] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited by these. Example 1 Exemplary compounds (4), (5), (lO) of the dye of the present invention,
(11), (28), (30) and (38) and the following comparative dyes (A) and (B), the absorption spectra and molar extinction coefficient (ε) in the visible light region were measured in ethyl acetate solvent. The results are shown in the table below. -2 Comparative dye (A) Comparative dye (B) Auxiliary undercoat [Note 1 (1) Δλ (0,2) is a value indicating the sharpness of absorption on the short wavelength side, and the absorbance is 20% of the absorbance at λmax. It is defined as the difference between the wavelength λ(0,2) on the short wave side and λmax, that is, Δλ(0,2)−λmax−λ(0,2). (2) λ1/2: As can be seen from the half-width or more, the cyan dye of the present invention has sharper absorption and higher ε (molar extinction coefficient) than conventional phenolic dyes. For example, when used as a cyan dye for imaging, this means that less dye is required to achieve a certain density, and the sharpness of the absorption means less secondary absorption in the edge regions. This shows that it is very advantageous in terms of color reproduction. Example 2 A coloring agent layer coating solution using a dispersion A having the following composition was coated on a polyethylene terephthalate film base having a thickness of 6 μm using a wire bar and dried to prepare a thermal transfer recording medium sample 1. Next, Samples 2.3 and 4 were prepared in the same manner as Sample 1 using the compounds (2), (3) and (4) of the present invention in place of the comparative dye (A). (Dispersion A) Comparative dye (A) Ig and tricresyl phosphene 1-
After dissolving 0.5 g in 3 mQ of ethyl acetate, 12 mff of 10% gelatin aqueous solution and 3.75% alkanol XC
4.5 mf2 of an aqueous solution (manufactured by DuPont) was added and dispersed for about 20 minutes using an ultrasonic disperser. After dispersion, about 80
Ethyl acetate was removed by heating to °C, and water was added to bring the total volume to 30 mQ. Each sample obtained was thermally transferred onto plain paper using a thermal head. However, the heating time is constant and the heating temperature is 10
It was varied in the range of 0 to 200°C. FIG. 1 shows the relationship between transfer temperature and transfer density. As is clear from FIG. 1, according to the present invention, a significant increase in sensitivity can be achieved even in thermal transfer. Example 3 A dispersion liquid having the following composition was applied using a wire bar onto a 9 μm thick polyethylene terephthalate film whose back surface had been heat-resistant treated and dried to form heat-sensitive recording medium samples 5 to 5.
7 was created. Next, Samples 8 to 13 were prepared using compounds (52), (53), and (54) of the present invention in place of the comparative dye (C). (Dispersion B) lOg of comparative dye (C), log of polysulfone resin, and 80g of chlorobenzene were mixed and treated with a paint conditioner for 10 minutes to prepare an ink. The dye and resin should be completely dissolved to obtain a uniform dispersion. (Dispersion C) Comparative dye (C) 3g, polyvinyl butyral resin 4.
5g, methyl ethyl ketone 45g, toluene 45g
g was mixed and prepared in the same manner as dispersion (B). (Dispersion D) 2 g of comparative dye (C), 8 g of ethyl cellulose, and 90 g of isopropanol were mixed and treated with a paint conditioner using glass beads for 30 minutes. Each of the obtained samples was thermally transferred onto the following image receiving paper using a thermal head. Receiving paper (1) Aqueous dispersion of 34% by weight of saturated polyester (Toyobo 1st grade ε Pyronal MD-1200) log and silica gel (Japan/Rica Kogyo N1psil E22OA) 5
Apply the paint prepared by mixing g to high-quality paper using a wire bar. Receiving paper (2) Polyester resin (Vylon 103 manufactured by Toyobo Co., Ltd.)
8 g, EVA polymer plasticizer (Mitsui Polychemical Elvaloy 741P) 2 g, amino-modified silicone (
Shin-Etsu Chemical KF-857) 0.4g, epoxy modified silicone (Shin-Etsu Chemical KF-103) 0.4
g, methyl ethyl ketone 36 g, t. toluene 36 g
, and 18 g of cyclohexane was applied to synthetic paper (Yupo FPG #150 manufactured by Oji Yuka Co., Ltd.). Receiving paper (3) Polycarbonate resin (1jakrolo manufactured by Bayer)
n5705) was dissolved in a mixture of methylene chloride and trichloroethylene and coated on a white polyester support, Merrix 990) manufactured by CICI. The above-mentioned thermal recording medium sample and the above-mentioned image-receiving paper are stacked with their respective dye-carrying layers and dye-receiving surfaces facing each other,
Head applied voltage 10V1 application time 4.0 from the back side of the sample
Recording was performed with a thermal head under m5ec conditions, and the following results were obtained. Shimano comparative dye (C)

Claims (1)

[Claims] An imidazole dye characterized by being represented by the following general formula [I]. General formula [I] ▲ Numerical formulas, chemical formulas, tables, etc. may form a ring. R
_3, R_4, R_5 and R_6 are each a hydrogen atom,
Represents a halogen atom, an alkyl group, a substituted alkyl group, an alkoxy group, a substituted alkoxy group or an acylamino group,
R_7 represents a monovalent organic group, m represents an integer of 0 to 5, and when m is 2 or more, plural R_7 may be the same or different. A represents an organic group bonded to the imidazole ring via a carbon atom, nitrogen atom, oxygen atom or sulfur atom. ]