JPH0211139B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel photoconductive coating and a highly sensitive electrophotographic photoreceptor using the same. Conventionally, pigments and dyes exhibiting photoconductivity have been published in numerous publications. For example, “RCAReview” Vol.23, P.413～
P.419 (September 1962), there was a presentation on the photoconductivity of phthalocyanine pigments, and electrophotographic photoreceptors using this phthalocyanine pigment were shown in U.S. Pat. No. 3,397,086, U.S. Pat. No. 3,816,118, etc. ing. In addition, examples of organic semiconductors used in electrophotographic photoreceptors include US Pat.
Publication No. 4315983, U.S. Patent No. 4327169,
Pyrylium dyes shown in “Reseach Disclosure” 20517 (May 1981), methine squaritate dyes shown in US Patent No. 3824099, US Patent No. 3898084, US Patent No.
Examples include disazo pigments disclosed in Publication No. 4251613 and the like. Such organic semiconductors are easier to synthesize than inorganic semiconductors, and can be synthesized as compounds that have photoconductivity for light in the required wavelength range. An electrophotographic photoreceptor formed on a conductive support has the advantage of improved color sensitivity, but only a few of them are practical in terms of sensitivity and durability. In particular, with the recent development of low-power semiconductor lasers,
The development of organic semiconductors with high sensitivity to long wavelength light such as 700 nm or more is becoming active. However, compounds with a large extinction coefficient for long wavelength light are generally unstable to heat, etc., and have problems such as being easily decomposed by a slight increase in temperature. This makes it substantially difficult to manufacture infrared-sensitive electrophotographic photoreceptors. Therefore, the first object of the present invention is to provide a novel organic semiconductor. A second object of the present invention is to provide a novel organic semiconductor coating. A third object of the present invention is to provide an electrophotographic photoreceptor using a novel organic semiconductor coating. A fourth object of the present invention is to provide an electrophotographic photoreceptor suitable for electrophotographic copying machines. A fifth object of the present invention is to provide an electrophotographic photoreceptor suitable for a laser beam scanning type electrophotographic printer. A sixth object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity to light in a long wavelength range. This object of the present invention is achieved by an azulenium salt compound represented by the following general formula (1). General formula (1) In the general formula, R ₁ to _{R 7} represent a hydrogen atom, a halogen atom (chlorine atom, bromine atom, iodine atom) or a monovalent organic residue. Monovalent organic residues can be selected from a wide range of options, but especially alkyl groups (methyl, ethyl, n-propyl,
isopropyl, n-butyl, t-butyl, n-amyl, n-hexyl, n-octyl, 2-ethylhexyl, t-octyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, butoxy, etc.), substituted or unsubstituted Aryl groups (phenyl, tolyl, xylyl, ethyl phenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, nitrophenyl, dimethylaminophenyl,
α-naphthyl, β-naphthyl, etc.), substituted or unsubstituted aralkyl groups (benzyl, 2-phenylethyl, 2-phenyl-1-methylethyl, bromobenzyl, 2-bromophenylethyl, methylbenzyl, methoxybenzyl, nitro benzyl), acyl groups (acetyl, propionyl, butyryl, valeryl, benzoyl, triooyl, naphthoyl, phthaloyl, furoyl, etc.), substituted or unsubstituted amino groups (amino, dimethylamino,
diethylamino, dipropylamino, acetylamino, benzoylamino, etc.), substituted or unsubstituted styryl groups (styryl, dimethylaminostyryl, diethylaminostyryl, dipropylaminostyryl, methoxystyryl, ethoxystyryl, methylstyryl, etc.), nitro group, hydroxy group, carboxyl group, cyano group, or substituted or unsubstituted arylazo group (phenylazo, α-naphthylazo, β-naphthylazo, dimethylaminophenylazo, chlorophenylazo, nitrophenylazo, methoxyphenylazo, tolylazo, etc.) be able to. Also, R ₁ and R ₂ , R ₃ and
Aromatic rings substituted or unsubstituted in at least one combination of R ₄ , R ₄ and R ₅ , R ₅ and R ₆ , and R ₆ and R ₇ (benzene, naphthalene, chlorobenzene, bromobenzene, methylbenzene , ethylbenzene, methoxybenzene, ethoxybenzene, etc.). R ₈ and R ₉ are hydrogen atoms, alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-
Butyl, t-butyl, n-amyl, n-hexyl, n-octyl, 2-ethylhexyl, t-octyl, nonyl, dodecyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, butoxy,
amyloxy, hexoxy, octoxy, etc.), substituted or unsubstituted aryl groups (phenyl, tolyl, xylyl, ethyl phenyl, methoxyphenyl, chlorophenyl, nitrophenyl, dimethylaminophenyl, dibenzylaminophenyl, α
-naphthyl, β-naphthyl, etc.), substituted or unsubstituted styryl group, or 4-phenyl-1,3-
Butadienyl group (styryl, methoxystyryl,
Dimethoxystyryl, ethoxystyryl, diethoxystyryl, dimethylaminostyryl, diethylaminostyryl, 4-phenyl-1,3-butadienyl, 4-(p-dimethylaminophenyl)-
1,3-butadienyl, 4-(p-diethylaminophenyl)-1,3-butadienyl, and the like. ) or a substituted or unsubstituted heterocyclic group (3-carbazolyl, 9-methyl-3-carbazolyl, 9-ethyl-3-carbazolyl, 9-carbazolyl, etc.), and R ₈ and R ₉ are bonded together. A substituted or unsubstituted benzene ring may be formed. Z represents a sulfur atom, an oxygen atom or a selenium atom. A represents an atom necessary to complete pyran, thiopyran, selenapyran, benzopyran, benzothiopyran, benzoselenapyran, naphthopyran, naphthothiopuran or naphthoselenapyran. These rings contain alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-butyl,
t-butyl, n-acyl, t-acyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, butoxy, etc.), substituted or unsubstituted aryl groups ( Phenyl, tolyl, xylyl, biphenyl, ethyl phenyl, methoxyphenyl, ethoxyphenyl, diethoxyphenyl,
Hydroxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, dibromophenyl,
nitrophenyl, diethylaminophenyl, dimethylaminophenyl, dibenzylaminophenyl, etc.), styryl, 4-phenyl-1,3-butadienyl, methoxystyryl, dimethoxystyryl, ethoxystyryl, diethoxystyryl, dimethylaminostyryl, 4- (p-dimethylaminophenyl)-1,3-butadienyl, 4-(p-
styryl group such as (diethylaminophenyl)-1,3-butadienyl or 4-phenyl-1,
It can be substituted by 3-butadienyl or a substituent thereof or a heterocyclic group such as 3-carbazolyl, 9-methyl-3-carbazolyl, 9-ethyl-3-carbazolyl, 9-carbazolyl. X represents an anionic residue such as perchlorate, picrate, fluoroborate, p-toluenesulfonate, periodide, chloride, bromide or iodide. n is 0 or 1. Representative examples of the compound represented by the general formula (1) are as follows.

【table】

【table】

[Table] The azulenium salt compound of the present invention has the following general formula:
A formyl azulene compound represented by (2) and general formula (2) (In the formula, R ₁ to _{R 7} mean the same as defined above.) The compound represented by the general formula (3) and the general formula (3) (In the formula, R ₈ , R ₉ , A, Z, X and n mean the same as defined above.) It can be easily obtained by reacting in a solvent. A wide range of organic solvents can be used as the solvent, but in particular alcohols such as ethanol, propanol, and butanol, nitriles such as acetone trile, ketones such as methyl ethyl ketone, nitro compounds such as nitrobenzene, and tetrachloroethane. Halogenated hydrocarbons such as , organic acids such as acetic acid, and acid anhydrides such as acetic anhydride are used. Next, a method for synthesizing typical azulenium salt compounds of the present invention will be described. Synthesis Example 1 Compound No. (2) In a three-necked flask, 1-formyl-3,8-
Dimethyl-5-isopropylazulene 3.0g, 4
-Methyl-2,6-diphenylpyrylium perchlorate (4.6 g) and acetic anhydride (100 ml) were charged, heated and stirred, and reacted at 80 to 90°C for 20 minutes. After cooling, the precipitated crystals were separated, washed with 50 ml of glacial acetic acid, and further washed twice with 600 ml of water and 250 ml of ethanol, and then dried to obtain 6.7 g of an azulenium salt compound. Yield: 91% Decomposition point: 260℃ or above Solution absorption spectrum: λmax 686nm in dichloromethane Elemental analysis: Molecular formula C ₃₄ H ₃₁ ClO ₅ Calculated value (%) Analytical value (%) C 73.56 73.43 H 5.64 5.80 Cl 6.39 6.45 Synthesis example 2 Compound No. (7) In a three-neck flask, add 3.0 g of 1-formyl-3,8-dimethyl-5-isoprolazulene, 4.8 g of 2-methyl-4,6-diphenylthiopyrylium perchlorate, and 100 ml of acetic anhydride. The mixture was charged, heated and stirred, and reacted at 90 to 105°C for 40 minutes.
After cooling, the precipitated crystals were separated, washed with 50 ml of glacial acetic acid, and further washed twice with 500 ml of water and 250 ml of ethanol, and then dried to obtain 7.0 g of an azulenium salt compound. Yield: 93% Decomposition point: 240-242℃ Solution absorption spectrum: λmax 743nm in dichloromethane Elemental analysis: Molecular formula C ₃₄ H ₃₁ ClO ₄ S Calculated value (%) Analytical value (%) C 71.49 71.36 H 5.48 5.54 Cl 6.21 6.29 The coating containing the azulenium salt compound described above exhibits photoconductivity, and therefore can be used as a photosensitive layer of an electrophotographic photoreceptor as described below. That is, in a specific example of the present invention, an electrophotographic photoreceptor is formed by forming a film of the azulenium salt compound on a conductive support by vacuum evaporation, or by forming a film by dispersing the azulenium salt compound in a suitable binder. It can be prepared. In a preferred embodiment of the present invention, the photoconductive coating described above can be applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5 microns or less, in order to shorten the range of the generated charge carriers. , preferably a thin film layer having a thickness of 0.01 micron to 1 micron. This means that most of the incident light is absorbed by the charge generation layer and generates a large number of charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, and the charge transport layer This is due to the need to inject. The charge generation layer can be formed by dispersing the above-mentioned compound in a suitable binder and coating it on the substrate. The binder that can be used to form the charge generating layer by coating can be selected from a wide range of insulating resins, as well as organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. can. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylpyridine, cellulose resin, urethane. Examples include insulating resins such as resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. The solvent that dissolves these resins varies depending on the type of resin, and is preferably selected from those that do not dissolve the charge transport layer or undercoat layer described below. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide,
Amides such as N,N-dimethylacetamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and aliphatic halogens such as chloroform, methylene chloride, cycloethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying at a temperature of 30℃ to 200℃ for 5 minutes to 2
It can be carried out stationary or under blown air for a period of time. The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. At this time, this charge transport layer may be laminated on or under the charge generation layer. However, it is desirable that the charge transport layer is laminated on the charge generation layer. The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" used herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both layers capture each other, resulting in a decrease in sensitivity. Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4,7-trinitro-9-fluorenone. , 2, 4, 5, 7-
Tetranitro-9-fluorenone, 2,4,7-
trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone,
Examples include electron-withdrawing substances such as 2,4,8-trinitrothioxanthone, and polymerization of these electron-withdrawing substances. Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
N-Methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-
3-methylidene-10-ethylphenothiazine,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, P-diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N
-α-naphthyl-N-phenylhydrazone, P-
Pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone hydrazones such as 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1
-Phenyl-3-(P-diethylaminostyryl)
-5-(P-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]- 3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[6-methoxy-pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1- [Pyridyl(3)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[Lepidyl(2)]-3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-
3-(P-diethylaminostyryl)-4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(P-diethylaminostyryl)-4-methyl-5
-(P-diethylaminophenyl)pyrazoline,
1-Phenyl-3-(α-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(P-diethylaminostyryl)
-6-diethylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2
Thiazole compounds such as -(P-diethylaminostyryl)-6-diethylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N -diethylamino-2-methylphenyl)heptane, 1,
Polyarylalkanes such as 1,2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-
N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Examples include poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin. In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used. Moreover, these charge transport substances may be one or two types.
More than one species can be used in combination. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N- Mention may be made of organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene, polyvinylpyrene. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Typically it is between 5 microns and 30 microns, with a preferred range between 8 microns and 20 microns. When forming the charge transport layer by coating, an appropriate coating method as described above can be used. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. As the substrate having a conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic, resin, polyethylene fluoride, etc.), conductive particles (e.g. carbon black,
A substrate made of plastic coated with silver particles (silver particles, etc.) together with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon
610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 micron to 5 micron.
Preferably, 0.5 micron to 3 micron is appropriate. When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones. On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged.
After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used. In another specific example of the present invention, organic photoconductive materials such as the aforementioned hydrazones, pyrazolines, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamines, poly-N-vinylcarbazoles, etc. The photosensitive coating may contain the above-mentioned compounds as sensitizers for inorganic photoconductive substances such as photoconductive substances, zinc oxide, cadmium sulfide, and selenium. This photosensitive film is formed by coating these photoconductive substances and the above-mentioned compound together with a binder. Each photoreceptor contains at least one kind of azulenium salt selected from the compounds represented by the general formula (1), and is used in combination with other photoconductive pigments or dyes having different light absorptions as necessary. In particular, it is possible to increase the sensitivity of this photoreceptor or to prepare it as a panchromatic photoreceptor. Hereinafter, the present invention will be explained according to examples. Examples 1 to 11 Ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 222 ml of water) on an aluminum plate
was applied with a Mayer bar so that the film thickness after drying was 1.0 microns, and dried. Next, 5 g of the 11 types of azulenium salts listed in the table below were added to a solution of 2 g of butyral resin (butyralization degree: 63 mol %) dissolved in 95 ml of isopropyl alcohol to prepare 11 types of coating solutions. After each coating liquid is dispersed with an attritor, the dry film thickness is
Apply with a Mayer bar to a thickness of 0.1 micron,
A charge generation layer was formed by drying. Then, the structural formula 5 g of hydrazone compound and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were added to benzene.
The solution was dissolved in 70 ml and applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 12 microns, and dried to form a charge transport layer. The 11 types of electrophotographic photoreceptors created in this way were tested using an electrostatic copying paper tester Model SP- manufactured by Kawaguchi Electric Co., Ltd.
428 using a static method with a corona charge of -5 KV, held in a dark place for 10 seconds, and then exposed to light at an illuminance of 5 lux to examine charging characteristics. The charging characteristics are the initial charging potential (V ₀ ) and 10
The exposure amount (E _1/2 ) required to attenuate the potential to 1/2 when dark decaying for a second was measured. This result is the first
Shown in the table. Further, the charge retention rate when dark decayed for 10 seconds was expressed as V _k (%).

[Table] Example 12 Polyester resin (manufactured by Toyobo Co., Ltd., Byron
200) 5g and 1-[pyridyl-(2)]-3-(4-N,
N-diethylaminostyryl)-5-(4-N,N
After dissolving 5 g of (diethylaminophenyl) pyrazoline in 80 ml of methyl ethyl ketone, 1.0 g of the aforementioned azulenium salt compound No. (7) was added and dispersed.
A photoreceptor having a photosensitive layer with a dry film thickness of 13 microns was prepared by coating and drying on a polyester film deposited with aluminum. The characteristics of this photoconductor were determined by the same method as in Example 1, including the initial charging potential (V ₀ ), the charge retention rate (V _k ) when dark decayed for 10 seconds, and the charging potential when dark decay was carried out for 10 seconds. When we measured the exposure amount required to attenuate by 1/2 (E _1/2) , it was as follows: V ₀ : -510 volts V _k : 80% E _1/2 : 34 lux.sec Example 13 1 g of poly-N-vinylcarbazole and 5 mg of the aforementioned azulenium salt compound No. (2) were added to 10 g of 1,2-dichloroethane and thoroughly stirred.The thus prepared coating solution was applied to a polyethylene terephthalate film on which aluminum was deposited. Dry film thickness on top of
It was applied with a doctor blade to a thickness of 15 microns. The charging characteristics of this photoreceptor were measured in the same manner as in Example 1. However, the charging polarity was determined.
The results are shown below. V ₀ : +490 volts V _k : 84% E _1/2 : 36.8 lux·sec Example 14 In place of the azulenium salt compound No. (2) used when preparing the electrophotographic photoreceptor of Example 13, the After preparing a photoreceptor in exactly the same manner as in Example 13 except for using azulenium salt compound No. (5),
The charging characteristics of this photoreceptor were measured. The results are shown below. However, the charging polarity was taken into account. V ₀ : +410 volts V _k : 79% E _1/2 : 32.0 lux・sec Example 15 Particulate zinc oxide (Sazex2000 manufactured by Sakai Chemical Co., Ltd.) 10
g, 4 g of acrylic resin (Dyanal LR009 manufactured by Mitsubishi Rayon Co., Ltd.), 10 g of toluene, and 10 mg of the above-mentioned azulenium salt compound No. (1) were thoroughly mixed in a ball mill, and the resulting coating liquid was applied to aluminum. It was applied onto the vapor-deposited polyethylene terephthalate film using a doctor blade to a dry film thickness of 21 microns, and dried to prepare an electrophotographic photoreceptor. When the spectral sensitivity of this electrophotographic photoreceptor was measured using spectrophotography using electrophotography, it was found that the photoreceptor of this example showed sensitivity on the long wavelength side compared to the aforementioned zinc oxide coating that did not contain an azulenium salt compound. It turned out that it has.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are explanatory diagrams showing visible-infrared absorption spectra of Compound No. (2) and Compound No. (7) in dichloromethane solutions.

Claims (1)

[Scope of Claims] 1. A photoconductive coating characterized by containing a compound represented by the following general formula (1). General formula (1) (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ represent a hydrogen atom, a halogen atom or a monovalent organic residue, and R ₁ and R ₂ , R ₃ and R ₄ , R ₄ and R ₅ , R ₅ and R ₆ , and R ₆ and R ₇ , at least one combination may form a substituted or unsubstituted aromatic ring. R ₈ and R ₉ is a hydrogen atom, an alkyl group,
It represents an alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted styryl group, a substituted or unsubstituted 4-phenyl-1,3-butadienyl group, or a substituted or unsubstituted heterocyclic group.
Furthermore, R ₈ and R ₉ may form a substituted or unsubstituted benzene ring. Z represents a sulfur atom, an oxygen atom or a selenium atom. A is optionally substituted pyran, thiopyran, selenapyran, benzopyran, benzothiopyran,
Indicates the atomic groups necessary to complete benzoselenapyran, naphthopyran, naphthothiopyran, or naphthoselenapyran. X represents an anionic residue. n is 0 or 1. ) 2 An electrophotographic photoreceptor comprising a photosensitive layer containing a compound represented by the following general formula (1) on a conductive support. General formula (1) (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ represent a hydrogen atom, a halogen atom or a monovalent organic residue, and R ₁ and R ₂ , R ₃ and R ₄ , R ₄ and R ₅ , R ₅ and R ₆ , and R ₆ and R ₇ , at least one combination may form a substituted or unsubstituted aromatic ring. R ₈ and R ₉ is a hydrogen atom, an alkyl group,
It represents an alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted styryl group, a substituted or unsubstituted 4-phenyl-1,3-butadienyl group, or a substituted or unsubstituted heterocyclic group.
Furthermore, R ₈ and R ₉ may form a substituted or unsubstituted benzene ring. Z represents a sulfur atom, an oxygen atom or a selenium atom. A is optionally substituted pyran, thiopyran, selenapyran, benzopyran, benzothiopyran,
Indicates the atomic groups necessary to complete benzoselenapyran, naphthopyran, naphthothiopyran, or naphthoselenapyran. X represents an anionic residue. n is 0 or 1. )