JPH0513500B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to electrophotographic photoreceptors, and more particularly to electrophotographic photoreceptors containing a low molecular weight organic photoconductor that provides improved electrophotographic properties. [Prior Art] Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are conventionally known as photoconductive materials used in electrophotographic photoreceptors. These photoconductive materials have many advantages, such as being able to be charged to an appropriate potential in the dark, having little charge dissipation in the dark, or quickly dissipating the charge when irradiated with light. However, it also has various drawbacks. For example, selenium-based photoreceptors easily crystallize due to factors such as temperature, humidity, dust, and pressure. Especially when the ambient temperature exceeds 40°C, crystallization becomes significant, resulting in decreased charging performance and white spots on images. Disadvantages that arise: Cadmium sulfide photoreceptors cannot provide stable sensitivity in humid environments, and zinc oxide photoreceptors require the sensitizing effect of a sensitizing dye such as rose bengal. but,
Such sensitizing dyes suffer from charging deterioration due to corona charging and photobleaching due to exposure light, so they have the disadvantage that they cannot provide stable images over a long period of time. On the other hand, various organic photoconductive polymers including polyvinylcarbazole have been proposed, but these polymers are superior to inorganic photoconductive materials in terms of film formability and light weight. However, it has been difficult to put them into practical use until now because they have not yet achieved sufficient film formation properties, and they are inferior to inorganic photoconductive materials in terms of sensitivity, durability, and stability against environmental changes. It was because it was hot. Also, hydrazone compounds described in US Pat. No. 4,150,987, triarylpyrazoline compounds described in US Pat. Low-molecular organic photoconductors have been proposed, such as the 9-styrylanthracene compound described in . These low-molecular-weight organic photoconductors have been able to overcome the film-forming drawbacks that had been a problem in the field of organic photoconductive polymers by appropriately selecting the binder used. , cannot be said to be sufficient in terms of sensitivity. For this reason, in recent years, a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has been proposed. An electrophotographic photoreceptor with this laminated structure as a photosensitive layer has high sensitivity to visible light, charge retention ability,
It has become possible to improve aspects such as surface strength. Such electrophotographic photoreceptors are described, for example, in US Pat. No. 3,837,851, US Pat. Furthermore, electrophotographic photoreceptors using low-molecular organic photoconductors in the charge transport layer are disclosed in Japanese Patent Publications No. 55-42380, Japanese Patent Application Laid-open No. 123544-1982, and Japanese Patent Publication No. 58-32372.
JP-A-58-197043 and the like are known. However, photoreceptors using these low-molecular-weight organic photoconductors in the charge transport layer are not necessarily satisfactory in terms of sensitivity, residual potential, or stability during repeated use, and the selection range of charge-generating materials is limited. However, it does not fully satisfy the wide range of requirements of electrophotographic processes. [Problems to be Solved by the Invention] An object of the present invention is to provide a novel organic photoconductive material, an electrophotographic photosensitive material containing a specific compound that is stable to heat and light and has excellent carrier transport. The object of the present invention is to provide an electrophotographic photoreceptor that can be used in all current electrophotographic processes and has practical high sensitivity characteristics and stable potential characteristics during repeated use. [Means for Solving the Problems, Effects] The present invention comprises an electrophotographic photoreceptor characterized by having a layer containing a compound represented by the following general formula (). general formula In the formula, X is an oxygen atom, a sulfur atom, or =NR ₂
, R ₁ is a hydrogen atom, an alkyl group, an alkoxy group, an alkylthio group, a halogen atom, a nitro group or a cyano group, and R ₂ is an alkyl group, an aralkyl group which may have a substituent, an aromatic ring group or a heterocycle Ar ₁ and Ar ₂ represent an alkyl group, an aromatic ring group that may have a substituent, or a heterocyclic group. Specifically, in R ₁ above, the alkyl group includes methyl, ethyl, propyl, butyl, etc., and the alkoxy group includes methoxy, ethoxy,
Groups such as propoxy, alkylthio groups include methylthio and ethylthio, halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, etc. In R ₂ above, alkyl groups include methyl, ethyl, propyl, etc. Examples of the aralkyl group include benzyl, phenethyl, naphthylmethyl, etc., aromatic ring groups include phenyl, naphthyl, etc., and heterocyclic groups include pyridyl, quinolyl, thienyl, furyl, etc. In Ar ₁ and Ar ₂ above, the alkyl group is a group such as methyl, and the aromatic ring group is phenyl,
Groups such as naphthyl, pyridyl as heterocyclic groups,
Examples include groups such as thienyl and furyl. Substituents for the above aralkyl group, aromatic ring group and heterocyclic group include fluorine atom, chlorine atom,
Halogen atoms such as iodine atoms and bromine atoms; alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy, ethoxy, and propoxy;
Alkylthio groups such as methylthio and ethylthio,
Examples include nitro group and cyano group. Representative examples of the compound represented by the general formula () are listed below. Synthesis Example (Synthesis of Compound Example (2)) 21.8 g (0.08 mol) of anisoin was added to a 300 ml three-necked flask equipped with a Gene Stark water separator.
7.44g (0.08mol) of aniline, 200ml of xylene
was added and stirred under reflux for 2 hours. At this time, water
1.3 ml was separated using a water separator. After cooling, the reaction solution was washed successively with water, dilute hydrochloric acid, 2% aqueous sodium carbonate solution, and saturated brine. After drying the organic layer with Glauber's salt, xylene was distilled off, and ethanol was added to the residue. The precipitated crystals were filtered and dried, and N-[p
22.2 g (yield 79.8%) of -methoxy-α-(p-methoxyphenyl)phenacyl]aniline was obtained. Next, in a 50 ml three-neck flask equipped with an air condenser, add 17.4 g (0.050 mol) of N-[p-methoxy-α-(p-methoxyphenyl) phenacyl]aniline, 12 ml of aniline, and 3 drops of 10% hydrochloric acid. Get in,
Heated at 160°C for 6 hours. After cooling, the reaction product was dissolved in ether, washed with 2% hydrochloric acid and water, and the ether layer was dried over sodium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography to obtain 15.3 g of 2,3-di(p-methoxyphenyl)indole (yield: 47.0
%)Obtained. 2,3-di(p-methoxyphenyl)indo-
Dissolve 14.0 g (0.043 mol) of 60% oil-based sodium hydride in 200 ml of DMF and stir under ice-cooling.
mol) slowly. 2 at room temperature after the addition is complete.
Stir for an hour. Then, under ice-cooling and stirring, methyl iodide was added.
3.5 ml (0.056 mol) was added dropwise over 30 minutes, and after the addition was completed, the mixture was stirred at room temperature for 3 hours. After the reaction is completed, the reaction product is poured into 1 liter of ice water and extracted with ether. The ether layer is dried with sodium sulfate and the solvent is distilled off. 1-Methyl-2,3-di(p-methoxyphenyl)indole (compound example (2)) was precipitated by adding petroleum ether to the residue.
Colorless crystals were collected by filtration. Yield: 11.8g Yield: 81.0% Melting point: 133-134°C Elemental analysis Calculated value (%) Experimental value (%) C 80.44 80.40 H 6.16 6.19 N 4.08 4.11 In addition, compounds represented by general formula () other than synthesis examples are also generally Synthesized using a similar method. In a preferred embodiment of the present invention, a compound represented by the above general formula () is used as a charge transporting substance in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. The charge transport layer in the present invention has the general formula ()
It is preferable to form the film by applying a solution in which the compound represented by and a binder are dissolved in a suitable solvent and drying the solution. Examples of the binder used here include polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester, alkyd resin, polycarbonate, polyurethane, or copolymer. Mention may be made of polymers such as styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and the like. In addition to such insulating polymers, organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene, and polyvinylpyrene can also be used. The blending ratio of this binder and the specific charge transport substance is 10 parts by weight of the charge transport substance per 100 parts by weight of the binder.
The amount is preferably 500 parts by weight. The charge transport layer is electrically connected to the charge generation layer described below, 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. are doing. 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. Since this charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 40 μm, but the preferred range is 10 to 30 μm. The organic solvent used to form such a charge transport layer varies depending on the type of binder used, and is preferably selected from those that do not dissolve the charge generation layer or the subbing layer described below. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol;
Ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, and methyl acetate. , esters such as ethyl acetate,
methylene chloride, dichloroethylene, carbon tetrachloride,
Aliphatic halogenated hydrocarbons such as trichloroethylene, aromatics such as benzene, toluene, xylene, 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 is generally preferably carried out at a temperature of 30 to 200° C. for 5 minutes to 2 hours, either stationary or under ventilation. The charge transport layer in the present invention may contain various additives. For example, plasticizers such as diphenyl, m-terphenyl, dibutyl phthalate, silicone oil, grafted silicone polymers, surface lubricants such as various fluorocarbons, dicyanovinyl compounds, potential stabilizers such as carbazole derivatives, β-carotene, Nickel complex, 1,4-diazabicyclo[2,2,
2] Antioxidants such as octane can be mentioned. The charge generation layer in the present invention includes inorganic charge generation substances such as selenium, selenium-tellurium, and amorphous silicone; cationic dyes such as pyrylium dyes, thiapyrylium dyes, azulenium dyes, thiacyanine dyes, and quinocyanine dyes;
Polycyclic quinone pigments such as squbarium salt dyes, phthalocyanine pigments, anthorone pigments, dibenzpyrenequinone pigments, and pyranthrone pigments, indigo pigments, quinacridone pigments,
Materials selected from organic charge-generating substances such as azo pigments can be used alone or in combination as a vapor deposited layer or a coating layer. Among the above-mentioned charge-generating substances, there are a wide variety of azo pigments in particular, and typical structural examples of particularly effective azo pigments will be described below. The general formula of an azo pigment is shown below as A for the central skeleton and Cp for the coupler part, where n
is 2 or 3, and a specific example will be given. A (N=N-Cp)n As a specific example of A, Examples include. The central skeleton A and the coupler Cp form a pigment serving as a charge-generating substance by appropriate combination. The charge-generating layer can be formed by dispersing the charge-generating substance described above in a suitable binder and coating it on a support, or by forming a vapor-deposited film using a vacuum evaporation device. It can be formed by twisting it. The binder can be selected from a wide range of insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (such as a polycondensate of bisphenol A and phthalic acid), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, Examples include epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and the like. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. Organic solvents used during coating include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl Sulfoxides such as sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and aliphatic halogenated compounds such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using a coating method similar to that used in forming the charge transport layer. The charge generation layer contains as much of the organic photoconductor as possible in order to obtain sufficient absorbance and contains a thin film layer, e.g. 5μm
Hereinafter, it is preferable to use a thin film layer having a thickness of preferably 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. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a support having a conductive layer. As the support having a conductive layer, the support itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel,
Vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. Plastics with formed layers (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g. aluminum powder, titanium oxide, tin oxide, zinc oxide,
A support obtained by coating plastic or the above-mentioned conductive support with carbon black, silver particles, etc.) together with a suitable binder, a support obtained by impregnating plastic or paper with conductive particles, a plastic containing a conductive polymer, etc. may be used. I can do it. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer is casein, polyvinyl alcohol,
It can be formed from nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, and the like. The thickness of the undercoat layer is 0.1 to 5 μm, preferably 0.5 to 5 μm.
3 μm 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, since the charge transport compound in the present invention has hole transport properties, it is necessary to charge the surface of the charge transport layer negatively; When exposed to light after being charged, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface to neutralize the negative charge, resulting in attenuation of the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use positively charged toner. In another embodiment of the present invention, the aforementioned disazo pigments or the disazo pigments described in U.S. Pat.
The photoconductivity of pyrylium dyes, thiapyrylium dyes, selenapyrylium dyes, benzopyrylium dyes, benzothiapyryllium dyes, naphtopyrylium dyes, naphthothiapyrylium dyes, etc. disclosed in 3567438, 3586500, etc. Pigments and dyes can also be used as sensitizers. In another specific example, a eutectic complex of a pyrylium dye and an electrically insulating polymer having an alkylidene diarylene moiety as disclosed in US Pat. No. 3,684,502 and the like can be used as a sensitizer. This eutectic complex is composed of, for example, 4-[4-bis(2-chloroethyl)aminophenyl]-2,6-diphenylthiapyrylium perchlorate and poly(4,
4'-isopropylidene diphenylene carbonate) in a halogenated hydrocarbon solvent such as dichloromethane, chloroform, carbon tetrachloride, 1,1-
dichloroethane, 1,2-dichloroethane, 1,
After dissolving in 1,2-trichloroethane, chlorobenzene, bromobenzene, 1,2-dichlorobenzene, etc., add a non-polar solvent such as hexane, octane, decane, 2,2,4-trimethylbenzene, ligroin, etc. can be obtained as a particulate eutectic complex by adding . The electrophotographic photoreceptor in this specific example includes styrene-butadiene copolymer, silicone resin,
Contains vinyl resin, vinylidene chloride-acrylonitrile copolymer, styrene-acrylonitrile copolymer, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, polymethyl methacrylate, poly-N-butyl methacrylate, polyesters, cellulose esters, etc. as a binder. I can do it. The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, and electrophotographic plate making systems. The electrophotographic photoreceptor of the present invention has the advantage of high sensitivity and small fluctuations in bright area potential and dark area potential when repeatedly charged and exposed. [Examples] Example 1 A coating solution was prepared by dispersing 5 g of a disazo pigment represented by the following structural formula together with a solution in which 2 g of butyral resin (degree of butyralization: 63 mol %) dissolved in 100 ml of scrohexanone in a sand mill for 24 hours. Apply this coating solution on an aluminum sheet until the dry film thickness is
A charge generation layer was formed by coating with a Meyer bar to a thickness of 0.2 μm. Next, 10g of compound example (2) as a charge transport substance
10 g of polycarbonate (average molecular weight: 20,000) were dissolved in 70 g of monochlorobenzene, and this solution was applied onto the charge generation layer using a Mayer bar to form a charge transport layer with a dry film thickness of 20 μm. A photoreceptor was created. The electrophotographic photoreceptor thus created was sold to Kawaguchi Electric Co., Ltd.
Using an electrostatic copying paper tester Model SP-428, the paper was corona charged at 5KV using static method, held in a dark place for 1 second, and then exposed to light at an illuminance of 20 lux.
The charging characteristics were investigated. As for charging characteristics, the surface potential (V ₀ ) and the exposure amount (E1/2) required to attenuate the potential (V ₁ ) by 1/2 when dark decayed for 1 second were measured. Furthermore, in order to measure the fluctuations in bright area potential and dark area potential during repeated use, the electrophotographic photoreceptor prepared in this example was used on a PPC copier NP manufactured by Canon Inc.
Attach it to the -3525 photosensitive drum cylinder,
5,000 copies were made using the same machine, and changes in dark area potential (V _D ) and light area potential (V _L ) were measured at the initial stage and after 5,000 copies were made. Note that the initial V _D and V _L were set to −700 V and −200 V, respectively. For comparison, compounds (A), (B), and
A similar electrophotographic photoreceptor was prepared using (C) and measured in the same manner. (Comparative Examples 1 to 3) Show the results.

[Table] As is clear from the above results, it can be seen that when the charge transport compound specified in the present invention is used, it has good sensitivity and less potential fluctuation during durability. Examples 2 to 15 In each of these Examples, in place of the charge transport compound example (2) used in Example 1, compound examples (3), (5), (6),
(7), (12), (15), (23), (24), (26), (28), (35), (40
),
An electrophotographic photoreceptor was prepared using (44) and (49) and a pigment having the following structural formula as a charge generating substance, but in the same manner as in Example 1 except for the following conditions. The electrophotographic properties of each photoreceptor were measured in the same manner as in Example 1. Show the results.

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[Table] Example 16 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 22.2 ml of water) was coated on an aluminum cylinder by a blade coating method to form a subbing layer with a dry film thickness of 1 μm. Next, 10 g of a charge generating substance shown by the following structural formula, 5 g of butyral resin (butyralization degree: 63 mol %) and 200 g of cyclohexanone were dispersed for 48 hours using a ball mill disperser. This dispersion was applied onto the previously formed subbing layer by a blade coating method to form a charge generation layer with a dry film thickness of 0.15 μm. Next, 10 g of compound example (2) and 10 g of polymethyl methacrylate (average molecular weight 50,000) were added to chlorobenzene.
Dissolved in 70g and coated on the previously formed charge generation layer using the blade coating method to determine the dry film thickness.
A charge transport layer of 19 μm was formed. A corona discharge of -5 KV was applied to the electrophotographic photoreceptor thus prepared. The surface potential at this time was measured (initial potential V ₀ ). Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 1 second. Sensitivity was evaluated by measuring the amount of exposure (E1/2, microjoule/cm ² ) required to attenuate the potential V ₁ after dark decay to 1/2. At this time, gallium/aluminum/
An arsenic ternary semiconductor laser (output: 5 mw, oscillation wavelength 780 nm) was used. Show the results. V ₀ : -720V V ₁ : -710V E1/2: 2.5 microjoules/cm ² Next, we used a laser beam printer (manufactured by Canon Inc.), which is a reversal development type electrophotographic printer equipped with the same semiconductor laser as above. , LBP-CX) was set in place of the photoreceptor of LBP-CX, and an actual image forming test was conducted. The conditions are: surface potential after primary charging: -700V, surface potential after image exposure: -150V (exposure amount: 2.0 microjoules/cm ² ), transfer potential: +700V, developer polarity: negative polarity, process speed: 50mm. /sec,
Development conditions (development bias): -450V, image exposure scan method: image scan, exposure before primary charging:
The entire surface was exposed to red light at 50 lux, sec. Image formation was performed by line scanning a laser beam in accordance with character and image signals, and good prints were obtained for both characters and images. Furthermore, when printing 3000 images continuously, good prints were obtained that were stable from the initial stage up to 3000 sheets. Example 17 4-(4-dimethylaminophenyl)-2,6-
3 g of diphenylthiapyrylium perchlorate and 5 g of Compound Example (15) were mixed into a toluene (50 parts by weight) - dioxane (50 parts by weight) solution of polyester (Polyester Adhesive 49000, manufactured by DuPont).
The mixture was mixed in 100ml and dispersed for 6 hours using a ball mill disperser. This dispersion was applied onto an aluminum sheet using a Mayer bar so that the film thickness after drying was 15 μm. The electrophotographic properties of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results. V ₀ : -690V V ₁ : -675V E1/2: 3.1lux, sec Initial V _D : -700V V _L : -200V After 5,000 sheets durability V _D : -695V V _L : -210V Example 18 4-( 4-dimethylaminophenyl)-2,6-
After fully dissolving 3 g of diphenylthiapyrylium perchlorate and 3 g of poly(4,4'-isopropylidene diphenylene carbonate) in 200 ml of dichloromethane, 100 ml of toluene was added to precipitate a eutectic complex. After filtering this precipitate, add dichloromethane to redissolve it, and then add n to this solution.
- 100 ml of hexane was added to obtain a precipitate of the eutectic complex. 5g of this eutectic complex and 2g of polyvinyl butyral
The mixture was added to 95 ml of a methanol solution containing 100 ml of methanol, and dispersed using a ball mill dispersion machine for 6 hours. This dispersion was spread on an aluminum plate with a casein layer so that the film thickness after drying was
A charge generation layer was formed by coating with a Mayer bar to a thickness of 0.4 μm. Next, a charge transport layer was formed on the charge generation layer in exactly the same manner as in Example 1 except that Compound Example (28) was used. The electrophotographic properties of the thus produced electrophotographic photoreceptor were measured in the same manner as in Example 1. Show the results. V ₀ : −720V V ₁ : −690V E1/2: 2.7lux, sec Initial V _D : −700V V _L : −200V After 5,000 sheets durability V _D : −695V V _L : −205V Example 19 On aluminum plate An ammonia aqueous solution of casein (described above) was applied to the substrate using a Mayer bar to form a subbing layer with a dry thickness of 1 μm. The charge transport layer and charge generation layer of Example 2 were sequentially laminated thereon, and an electrophotographic photoreceptor was prepared in the same manner as in Example 2 except for the layer structure, and the charging properties were the same as in Example 2. was measured. However, the charging polarity was set to +. Show the results. V ₀ : +750V V ₁ : +720V E1/2: 2.8lux, sec Example 20 Soluble nylon (6-66-610-
A 5% methanol solution of 12 quaternary nylon copolymer) was applied to form an undercoat layer with a dry thickness of 0.5 μm. Next, 5 g of a pigment having the following structural formula was dispersed in 95 ml of tetrahydrofuran using a sand mill disperser for 20 hours. Next, 5 g of compound example (1) and bisphenol Z type polycarbonate (viscosity average molecular weight 30,000) 10
A solution obtained by dissolving g in 30 ml of monochlorobenzene was added to the dispersion prepared earlier, and the mixture was further dispersed in a sand mill for 2 hours. This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying would be 20 μm, and then dried. The electrophotographic properties of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results. V ₀ :-705V V ₁ :-690V E1/2 : 3.0lux, sec [Effect of the invention] The electrophotographic photoreceptor containing the compound represented by the general formula () of the present invention has high sensitivity and can be repeatedly charged. There is an electrophotographic photoreceptor that has excellent durability and has small fluctuations in bright area potential and dark area potential during continuous image formation by exposure.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a layer containing a compound represented by the following general formula (). general formula In the formula, X is an oxygen atom, a sulfur atom, or =NR ₂
, R ₁ is a hydrogen atom, an alkyl group, an alkoxy group, an alkylthio group, a halogen atom, a nitro group or a cyano group, and R ₂ is an alkyl group, an aralkyl group which may have a substituent, an aromatic ring group or a heterocycle Ar ₁ and Ar ₂ represent an alkyl group, an aromatic ring group that may have a substituent, or a heterocyclic group.