JPH0448221B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a novel photoconductive coating and a highly sensitive electrophotographic photoreceptor using the same. BACKGROUND ART Conventionally, pigments and dyes exhibiting photoconductivity have been published in numerous publications. For example, “RCA Review” 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, as organic semiconductors used in electrophotographic photoreceptors, for example, US Pat.
4315983, U.S. Patent No. 4327169 and “Reseach Disclosure” 20517 (May 1981), pyrylium dyes, U.S. Patent No. 3824099, methine squaritate dyes, U.S. Patent No. 3898084 Publication, U.S. 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. Electrophotographic photoreceptors formed on conductive supports have the advantage of improved color sensitivity, but only a few of them have the sensitivity and durability to be used. Problems to be Solved by the Invention The first object of the present invention is to provide a highly sensitive organic semiconductor coating. A second object of the present invention is to provide an electrophotographic photoreceptor using a photoconductive film made of a highly sensitive organic semiconductor. A third object of the present invention is to provide an electrophotographic photoreceptor suitable for electrophotographic copying machines. Means and Effect for Solving the Problems The present invention provides a photoconductive film containing a dithiylium salt compound represented by the following general formula (1), (2) or (3) and a conductive support as shown below. General formula (1), (2) or (3)
The electrophotographic photoreceptor is characterized by being provided with a photosensitive layer containing a dithiylium salt compound represented by: General formula (1) In the formula, l is an integer of 0, 1 or 2; , lower alkyl groups such as ethyl, propyl, and butyl; aralkyl groups such as benzyl and phenethyl; and aryl groups such as phenyl, naphthyl, and insulin; Lower alkyl groups such as, halogen atoms such as fluorine, chlorine, bromine, iodine, nitro groups,
It may be substituted with a cyano group, a lower alkoxy group such as methoxy, ethoxy, or propoxy, or a substituted amino group such as dimethylamino, diethylamino, or dibenzylamino. R ₁ is an aromatic hydrocarbon group derived from benzene, naphthalene, anthracene, pyrene, fluorene, etc., which may have a substituent, or phenothiazine, phenoxazine, carbazole, indole, pyrrole, ifrane, thiophene, dibenzofuran, acridine, etc. Represents a derived heterocyclic group, and substituents include lower alkyl groups such as methyl, ethyl, propyl, butyl, lower alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, aryloxy groups such as phenoxy, methyl mercapto, ethyl mercapto. Alkylmercapto groups such as amino groups, dialkylamino groups such as dimethylamino, diethylamino, dipropylamino, dibutylamino, dialkylamino groups such as dibenzylamino, diarylamino groups such as diphenylamino, methylphenylamino, ethylphenylamino , alkylaryl amino groups such as dianoethylphenylamino and chloroethylphenylamino, alkylararylamino groups such as benzylmethylamino, benzylethylamino, and benzylcyanoethylamino, aralkylarylamino groups such as benzylphenylamino, piperidino, Cyclic amino groups such as morpholino and pyrrolidino, β-arylethylene groups such as p-dimethylaminostyryl, p
Examples include arylazo groups such as -dimethylaminophenylazo. A ^- is an anionic group, and specific examples include:
I ^- , Br ^- , Cl ^- , ClO ₄ ^- , BF ₄ ^- , PF ₄ ^- ,

[Formula] Anions such as CH ₃ SO ₃ ^- , C ₂ H ₃ SO ₃ ^- , CH ₃ SO ₄ ^- are included. General formula (2) _{In the formula , _} ^- has the same meaning as A ^- in general formula (1). General formula (3) In the formula, m is an integer of 0, 1, 2 or 3, and n is 0
or an integer of 1, X and ^{A -} in general formula (1)
Synonymous with , Y represents an O, S, Se or Te atom as Y' or >N-R ₄ as Y'', provided that,
_R4 is an alkyl group such as methyl, ethyl, propyl, butyl, 2-hydroxyethyl, 2-methoxyethyl, 2-ethoxyethyl, 3-hydroxypropyl, 3-methoxypropyl, 3-ethoxypropyl, 3-chloropropyl , 3-bromopropyl, substituted alkyl groups such as 3-carboxypropyl, substituted or unsubstituted aralkyl groups such as benzyl, phenethyl, α-naphthylmethyl, chlorobenzyl, bromobenzyl, etc., substitutions such as phenyl, tolyl, naphthyl, nitrophenyl, etc. or represents an unsubstituted aryl group, etc. Z is pyridine, thiazoline, thiazole, benzthiazole, naphthothiazole, oxazoline, oxazole, benzoxazole, naphthoxazole, imidazoline, imidazole, benzimidazole, naphthimidazole, benzselenazole, quinoline,
isoquinoline, indole, oxadiazole,
Thiadiazole, pyrylium, benzpyryllium, naphtopyrylium and its 0 atoms are replaced with S, Se,
Te-substituted heterocycles and benzdithygyllium,
Indicates a residue forming a heterocycle containing >N-R ₄ or -O-, -S-, -Se-, -Te- in the ring such as naphthothiillium, and such a heterocycle includes fluorine,
Substituted with halogen atoms such as chlorine, bromine, and iodine, alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, and aryl groups such as nitro, phenyl, and tolyl. It's okay. Substituents for the H atom attached to the C atom in the chain connecting two heterocycles include halogen atoms such as fluorine, chlorine, bromine, and iodine; cyano groups; alkyl groups such as methyl, ethyl, propyl, and butyl; Examples include alkoxy groups such as methoxy, ethoxy, propoxy and butoxy; alkylmercapto groups such as methylmercapto, ethylmercapto and butylmercapto; and aryl groups such as phenyl. Next, a general method for producing the dithiylium salt compound used in the present invention will be described. The compound represented by general formula (1) is (The symbols in each reaction formula have the same meaning as the symbols in general formula (1), and l' indicates l-1). This method is described in Helv.Chim.Acta. 46 , 2167 (1963) J.Org.
Chem, 29 , 1711 (1964) and others. The compound of general formula (2) is (The symbols in each reaction formula have the same meaning as the symbols in general formula (2)) are generally synthesized. The compound of general formula (3) is It is generally synthesized by methods such as (The symbols in the reaction formula have the same meanings as those in general formula (3), and R ₅ represents a hydrogen atom or a substituent thereof in the chain connecting the two heterocycles). Methods for synthesizing these compounds are described in Helv. Chim. Acta. 46 , 2167 (1963) Introduction to Photographic Pigments (Kogyo Tosho Co., Ltd., published in 1938). Specific examples of the dithiylium salt compounds used in the present invention are listed below. The coating containing the dithiylium salt compound described above exhibits photoconductivity and can therefore be used in the photosensitive layer of the electrophotographic photoreceptor described below. That is, in a specific example of the present invention, an electrophotographic photoreceptor is formed by forming a film of the above-mentioned dithiylium salt compound on a conductive support by vacuum evaporation, or by dispersing it in a suitable binder and forming a film. 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, 5μ or less, in order to shorten the range of the generated charge carriers. ,Preferably
Preferably, the layer has a thickness of 0.01 to 1 μm. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection. The charge generation layer can be formed by dispersing the above-mentioned compound in a suitable binder and coating it on the substrate, or it can be obtained by forming a vapor deposited film using a vacuum vapor deposition apparatus. . The binder that can be used when forming the charge generation layer by coating can be selected from a wide range of insulating resins.
It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide,
Polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein,
Examples include insulating resins such as 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-dimethylseketamide,
Sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogens such as chloroform, methylene chloride, dichloroethylene, 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 can be carried out at a temperature of 30 to 200° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation. 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, if the charge generation layer is the uppermost layer, the coating may be scratched during repeated use, causing a change in sensitivity, so it is desirable that the charge transport layer be 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 trap 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-fluoretone, 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. Generally, it is 5μ to 30μ, with a preferred range of 8μ to 20μ. 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 the 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 (such as 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 to 5μ, preferably 0.5 to 3μ.
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 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 transporting substance is used. Furthermore, it is also possible to form a single-layer type photoreceptor in which a dithiylium salt compound is dispersed in the binder resin. 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 dithiylium salt compound described above as a sensitizer for photoconductive substances and inorganic photoconductive substances such as zinc oxide, cadmium sulfide, and selenium. This photosensitive film is formed by coating these photoconductive substances and the above-mentioned dithiylium salt compound together with a binder. Further, as another specific example of the present invention, JP-A-49-
It can also be used as a type of photoreceptor in which a charge generating material is dispersed in a charge transfer complex as disclosed in Japanese Patent No. 91648 (photoconductive member). General formula (1), (2) or (3) in any photoreceptor
The sensitivity of this photoreceptor can be increased by containing at least one type of dithiylium salt compound selected from the compounds represented by: It is also possible to prepare a photoreceptor that is highly sensitive or panchromatic. The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines but also for laser beam printers,
It can also be widely used in electrophotographic applications such as LED printers and CRT printers. Hereinafter, the present invention will be explained according to examples. Example 1 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 1.0μ, and dried. Next, to a solution of 2 g of butyral resin (degree of butyralization: 63 mol %) dissolved in 95 ml of isopropyl alcohol, 5 g of each of the 33 types of dithiylium salt compounds listed in the table below were added to prepare 33 types of coating solutions. After dispersing each coating solution in a sand mill for 4 hours, each coating solution was applied onto the casein undercoat layer using a Mayer bar so that the film thickness after drying was 0.1μ, and dried to form a charge generation layer. Ta. 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 μm, and dried to form a charge transport layer. The 33 types of electrophotographic photoreceptors prepared in this way were tested using an electrostatic copying paper tester Model SP-428 manufactured by Kawaguchi Electric Co., Ltd.
The sample was statically charged with a corona at -5KV using a 1000V, held in a dark place for 1 second, and then exposed to light for 4 seconds at an illuminance of 5lux to examine the charging characteristics. As for the charging characteristics, the initial charging potential (V ₀ ) and the exposure amount (El/2) required to attenuate the potential to 1/2 after dark decay for 1 second were measured. The results are shown in Table 1. In addition, the residual potential after 20 lux·sec exposure was expressed as _VR .

【table】

[Table] Comparative Examples 1 to 5 Photoreceptors were prepared in exactly the same manner as in Example 1 except that the dithiylium salt compound of Example 1 was replaced with the following comparative compounds, and the characteristics were investigated. The results are shown in Table 2.

【table】

【table】

[Table] All comparative examples have lower sensitivity and higher residual potential than the examples. Furthermore, using the charge measuring device of Example 1, corona charging was performed statically with an applied voltage of -5 KV, dark decay was performed for 1 second, and then exposed to light at an illuminance of 20 lux for 1 second, and the same charging operation was repeated 5000 times until the initial charging potential was V ₀ . The changes in residual potential V _R after exposure were investigated and the results are shown in Table 3. In addition, Examples 21, 22, 1,
The same measurements were performed on photoreceptors Nos. 4, 14, and 19.

[Table] Although the photoreceptors in the comparative examples all have high initial residual potentials, the residual potentials during repeated use are extremely high and are pushed up to the residual potential, resulting in high V ₀ and low potential stability during use, which is a major problem. be. On the other hand, the examples according to the present invention have excellent characteristics in both initial sensitivity and residual potential, and the characteristics after repeated use are also extremely stable. Example 34 Polyester resin (manufactured by Toyobo Co., Ltd., Vylon)
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 dithiylium salt compound No. 21 was added and dispersed.
A photoreceptor having a photosensitive layer with a dry film thickness of 13 μm was prepared by coating and drying on a polyester film on which aluminum was vapor-deposited. The characteristics of this photoreceptor were determined by using the same method as in Example 1 to determine the initial charging potential (V ₀ ) and the exposure amount required to attenuate the charging potential by half (El/2 ) was measured, and the results were as follows. (However, the charging polarity was set.) V ₀ : +570V E1/2 : 3.4lux・sec Example 35 1 g of poly-N-vinylcarbazole and 5 mg of the aforementioned dithiylium salt compound No. 22 were added to 10 g of 1,2-dichloroethane. After the addition, the mixture was thoroughly stirred. The coating solution thus prepared was applied onto a polyethylene terephthalate film on which aluminum was vapor-deposited using a doctor blade so that the dry film thickness was 15 μm. 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 : +560V E1/2 : 3.4lux・sec Example 36 The dithiylium salt compound No. 44 was used in place of the dithiylium salt compound No. 22 used when preparing the electron photoreceptor of Example 35. A photoreceptor was prepared in exactly the same manner as in the example, and then the charging characteristics of this photoreceptor were measured. The results are shown below. However, the charging polarity was taken into account. V ₀ : +580V E1/2: 3.3lux・sec Example 37 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 dithiylium salt compound No. 38 were thoroughly mixed in a ball mill, and the resulting coating solution was used for aluminum vapor deposition. The film was coated onto the prepared polyethylene terephthalate film using a doctor blade to a dry film thickness of 21 μm, 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 zinc oxide coating that did not contain the dithiylium salt compound mentioned above. It turned out that it has. Example 38 A polyvinyl alcohol film having a thickness of 1.1 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, a coating solution containing the same dithiylium salt compound as in Example 6 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.1μ, and dried. A charge generation layer was formed. Then, the structural formula A solution prepared by dissolving 5 g of pyrazoline compound and 5 g of polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 70 ml of tetrahydrofuran was placed on the charge generation layer to determine the film thickness after drying.
It was applied to a thickness of 10μ and dried to form a charge transport layer. The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in the examples. The results are shown below. V ₀ :-610V E1/2 : 2.4lux·sec Example 39 An ammonia aqueous solution of casein was coated on an aluminum plate with a thickness of 100μ and dried to form a subbing layer with a thickness of 1.1μ. Next, 5 g of 2,4,7-trinitro-9-fluorenone and 5 g of poly-N-vinylcarbazole (number average molecular weight 300,000) were added to 70 ml of tetrahydrofuran.
to form a charge transfer complex. This charge transfer complex compound and the aforementioned dithiylium salt compound No.
15. 1g of polyester resin (Byron: Toyobo
Co., Ltd.) was dissolved in 70 ml of tetrahydrofuran and dispersed. This dispersion was applied onto the undercoat layer so that the film thickness after drying was 12 μm, and dried. The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. These results were as follows. However, the charging polarity was determined. V ₀ : +580V E1/2 : 3.2lux·sec Example 40 A polyvinyl alcohol film having a thickness of 1.1 μm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film. Next, the above-mentioned dispersion of dithiylium compound No. 36 used in Example 27 was applied onto the previously formed polyvinyl alcohol layer using a Mayer bar so that the film thickness after drying was 0.5μ, and then dried. A charge generation layer was formed. Next, the structural formula A solution prepared by dissolving 5 g of pyrazoline compound and 5 g of polyarylate resin (condensation polymer of bisphenol A and terephthalic acid-isophthalic acid) in 70 ml of tetrahydrofuran was placed on the charge generation layer to determine the film thickness after drying.
It was applied to a thickness of 10μ and dried to form a charge transport layer. Example 1 shows the charging characteristics of the photoreceptor thus prepared.
It was measured using the same method as above. The results were as follows. V ₀ :-600V E1/2 : 2.3lux・sec Effects of the Invention As described above, the present invention provides a highly sensitive photoconductive film and realizes a highly sensitive electrophotographic photoreceptor. be.

Claims (1)

[Scope of Claims] 1. A photoconductive coating containing a dithiylium salt compound represented by the following general formula (1), (2) or (3). General formula (1) In the formula, l is an integer of 0, 1 or 2, X is a dithiylium ring which may have a substituent, a residue for forming a 4,5-dihydrodithiylium ring, R ₁ is
The aromatic hydrocarbon group or heterocyclic group which may have a substituent, A ^- represents an anion group. General formula (2) In the formula, X has the same meaning as X in general formula (1), and R ₂ and R ₃ are
Synonymous with R ₁ in general formula (1), provided that R ₂ and R ₃ may be the same or different, and A ^- has the same meaning as A ^- in general formula (1). General formula (3) In the formula, m is an integer of 0, 1, 2 or 3, and n is 0
or an integer of 1, X is synonymous with x in general formula (1), Y
is an O, S, Se or Te atom or
Y'' represents >N-R ₄ , provided that R ₄ is a substituted or unsubstituted alkyl group, aralkyl group, or aryl group, and Z is a 5- to 6-membered heterocyclic ring that may have a substituent. , or a residue for forming a 5- to 6-membered heterocycle condensed with an aromatic ring such as benzene or naphthalene which may have a substituent, and 2
The hydrogen attached to the carbon atom in the chain connecting the heterocycles may be substituted with a functional group, and A ^- is
It has the same meaning as A ^- in general formula (1). 2 The following general formula (1), (2) or (3) is placed on the conductive support.
An electrophotographic photoreceptor comprising a photosensitive layer containing a dithiylium salt compound represented by: General formula (1) In the formula, l is an integer of 0, 1 or 2, X is a dithiylium ring which may have a substituent, a residue for forming a 4,5-dihydrodithiylium ring, R ₁ is
The aromatic hydrocarbon group or heterocyclic group which may have a substituent, A ^- represents an anion group. General formula (2) In the formula, X has the same meaning as X in general formula (1), and R ₂ and R ₃ are
Synonymous with R ₁ in general formula (1), provided that R ₂ and R ₃ may be the same or different, and A ^- has the same meaning as A ^- in general formula (1). General formula (3) In the formula, m is an integer of 0, 1, 2 or 3, and n is 0
or an integer of 1, X is synonymous with x in general formula (1), Y
is an O, S, Se or Te atom or
Y'' represents >N-R ₄ , provided that R ₄ is a substituted or unsubstituted alkyl group, aralkyl group, or aryl group, and Z is a 5- to 6-membered heterocyclic ring that may have a substituent. , or a residue for forming a 5- to 6-membered heterocycle condensed with an aromatic ring such as benzene or naphthalene which may have a substituent, and 2
The hydrogen attached to the carbon atom in the chain connecting the heterocycles may be substituted with a functional group, and A ^- is
It has the same meaning as A ^- in general formula (1). 3. The electrophotographic photoreceptor according to claim 2, wherein the photosensitive layer is formed by sequentially laminating at least a charge generation layer containing a dithiylium salt compound according to claim 2 and a charge transport layer.