JPH0549106B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION This invention relates to electrophotographic photoreceptors, and more particularly to electrophotographic photoreceptors having an organic photoconductor that provides improved electrophotographic properties. [Prior Art] Conventionally, inorganic photoconductive materials such as cadmium selenium sulfide and zinc oxide have been known as photoconductive materials used in electrophotographic photoreceptors. On the other hand, many organic photoconductive polymers, including polyvinylcarbazole, have been proposed, but these have not yet achieved sufficient film-forming properties, and they have problems with sensitivity, durability, and stability against environmental changes. Inferior to photoconductive materials. Furthermore, low-molecular organic photoconductive materials such as hydrazone compounds, triarylpyrazoline compounds, and styryl anthracene compounds have been proposed. These low-molecular organic photoconductors have been able to overcome the film-forming problems that had been a problem in the field of organic photoconductive polymers by appropriately selecting the binder to be used. , it is still not sufficient in terms of sensitivity. For these reasons, a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has been proposed in recent years. Electrophotographic photoreceptors using this laminated structure as a photosensitive layer can now be improved in terms of sensitivity to visible light, charge retention, surface strength, and the like. Such an electrophotographic photoreceptor is disclosed in, for example, US Pat. No. 3,837,851;
This is disclosed in Publication No. 3871882, etc. However, the sensitivity of conventional electrophotographic photoreceptors using low-molecular organic photoconductors in the charge transport layer is not satisfactory, and the potential characteristics deteriorate when repeatedly charged and exposed. In particular, as the number of repetitions increases, the bright area potential and the dark area potential vary greatly, which is a fundamental defect of low-molecular organic photoconductors. [Problems to be Solved by the Invention] An object of the present invention is to provide a novel organic photoconductor that has good sensitivity and excellent durability against repeated use. Another object of the present invention is to provide a novel charge transport material in a laminated photosensitive layer in which a charge generation layer and a charge transport layer are functionally separated. [Means for Solving the Problems] According to the present invention, an electrophotographic photoreceptor is provided, which is characterized by having a photosensitive layer containing a compound represented by the following general formula or as a photoconductive substance: [In the formula, R ₁ represents a hydrogen atom or an alkyl group, an aryl group, or an aralkyl group that may have a substituent,
R ₂ represents a hydrogen atom or an alkyl group, and X ₁ and X ₂
each represents a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group, or a halogen atom;
Ar ₁ −CH=CH− or Ar ₁ −CH=CH−Ar ₂
- (where Ar ₁ and Ar ₂ each represent an aromatic ring or a heterocycle which may have a substituent), and n is an integer of 1 or more]. In the definition of R ₁ in the general formulas and formulas, the alkyl group is methyl, ethyl, propyl, butyl, etc., the aryl group is exemplified by phenyl, naphthyl, etc., and the aralkyl group is exemplified by benzyl, phenethyl, naphthylmethyl, etc. The above alkyl group may be substituted with an alkoxy group such as methoxy, ethoxy, propoxy, butoxy, or a halogen atom such as fluorine, chlorine, bromine, or iodine. Furthermore, the above aryl group and aralkyl group may be substituted with an alkoxy group such as methoxy, ethoxy, propoxy, or butoxy, a halogen atom such as fluorine, chlorine, or bromine, or a dialkylamino group such as dimethylamino, diethylamino, or dipropylamino. good. The alkyl group in R ₂ is, for example, methyl, ethyl, propyl, butyl. Examples of the alkyl group, alkoxy group, aralkyl, and halogen in X ₁ and X ₂ are the same as those mentioned above. Furthermore, in the definitions of Ar ₁ and Ar ₂ , aromatic rings are, for example, phenyl, naphthyl, etc., heterocycles are exemplified by pyridine, quinoline, etc., and furthermore, these aromatic rings and heterocycles are alkoxy groups, halogens, alkyl, It may be substituted with an amino group substituted with an aralkyl or aryl group, or a cyclic amino group. Representative examples of compounds represented by the general formulas and are shown below. Next, a synthesis example of the above compound will be shown. Synthesis of compounds (1), (27), (28), (29) N-methyldiphenylamine 18.3g (0.1mol),
7 ml of agricultural hydrochloric acid, 40 ml of ethanol, and 9.9 g (0.075 mol) of cinnamaldehyde were heated at 80°C for 30 hours with stirring, and after cooling, the liquid phase was removed by decantation, and the mixture was thoroughly washed with hot ethanol to obtain a pale yellow lumpy product. I got it. After vacuum drying, it was dissolved in hot bezene, treated with diluted soda solution, dehydrated, developed in an alumina column, the initial eluate fraction 1.2 was concentrated, and the precipitated powder was washed with hot ethanol to obtain 23.7 g of the target product. . The structure of the product was determined by NMR measurements to have a molar ratio of amine base to benzaldehyde base of approximately 4:3, i.e. n
It turns out that the number is 2. 15.4g of N-methyldiphenylamine
(0.0844mol) 14.8g (0.0808mol) 14.2g
Compounds (27), (28), and (29) were synthesized by changing (0.0774 mol) and treating the same as above. However, (28) and (29) required reaction times of 60 hours and 100 hours, respectively. Also (27),
For (28) and (29), NMR and GPC are used for n number.
It was used in conjunction with molecular weight measurement by Other compounds were basically synthesized by condensation reactions of aldehyde derivatives and diphenylamine derivatives or carbazole derivatives in accordance with the above synthesis method. The control of n number is the charging molar ratio and
This can be achieved by adjusting the heating time. Note that the products obtained by the above synthesis method often contain a polymeric component and the number n is not necessarily single, but since the polymeric component is usually in a small amount, it is used as is. If the number n is 10 or less, it is possible to remove the polymer component by preparative GPC to obtain a single product, but there is almost no difference in the properties as an organic photoreceptor whether it is a single product or a mixture. In a preferred embodiment of the present invention, a compound of the above general formula can be used as a charge transport substance and binder in an electrophotographic photoreceptor having functionally separated charge generation layer and charge transport layer. The larger the number of n in the general formula and, the higher the performance of the compound as a binder, but on the other hand, the properties as a photoconductor deteriorate, so the number of n is preferably 30 or less. However, if n is 0, defects in the low-molecular charge transport material will appear strongly, so n must be 1 or more. Further preferred embodiments of the present invention include using a compound with a small n number together with a suitable binder, using a compound with a large n number together with a known low-molecular charge transport substance, and using a suitable binder and a known low-molecular charge transport substance. Examples include using a mixture of the transport substance and the compound according to the invention. By using the organic photoconductor of the present invention in the photosensitive layer, the amount of binder that cannot become a photosensitive component can be eliminated or greatly reduced, making it possible to achieve high sensitivity and also Because it has better stability than other low-molecular charge transport materials, it is characterized by less deterioration of potential characteristics due to repeated charging and exposure. The charge transport layer according to the present invention is a coating solution prepared by dissolving or dispersing the compound represented by the above general formulas and, if necessary, a known binder and, if necessary, a known low-molecular charge transport substance in a suitable solvent. It is preferable to form the film by coating the film directly or through another layer on the substrate and drying it. Examples of the binder used here include polyarylate resin, polysulfone resin, polyamide resin,
Acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenolic resin, epoxy resin, polyester resin,
Examples include alkyd resins, polycarbonates, polyurethanes, and copolymer resins containing two or more repeating units of these resins, such as styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and the like. In addition, other low molecular charge transport substances include chloranyl, promoanil, toteracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7- Examples of electron-withdrawing substances include tetranitro-9-fluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone, and 2,4,8-trinitrothioxanthone. Examples of hole transporting substances include pyrene, 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,
Hydrazones such as P-diethylbenzaldehyde-3-methylbenzthiazolino-2-hydrazone, 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-penzyl-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 and the like can be used. When the compound of the general formula and according to the present invention is used as a charge transport material, the compounding ratio with the binder is 100 to 100 parts by weight of the compound per 100 parts by weight of the binder.
The amount is preferably 500 parts by weight. In addition, when the compound is used as a charge transport substance and also as a binder, the blending ratio with other low molecular charge transport substances is 0 to 300 parts by weight per 100 parts by weight of the compound. It is preferable to set it as part.
In this case, the necessary binder performance is imparted when the number n of the compound is 7 or more. When using a three-component system by adding a known binder, the proportion of the binder is preferably 40% or less of the solid content. 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. Since this charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. In general,
5 microns to 30 microns, with a preferred range of 8 microns to 20 microns. 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 acetone, methyl ethyl ketone,
Ketones such as cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, methyl acetate, ethyl acetate, etc. esters, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzene. Can be used. Coating can be performed 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 within a range of hours. The charge transport layer of the present invention can contain various additives. Such additives include diphenyl, diphenyl chloride, O-terphenyl,
P-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, dilaurylthiopropionate, 3,5-dinitrosalicylic acid,
Examples include various fluorocarbons. The charge generating layer used in the present invention includes amorphous silicon, selenium-arsenic, selenium-tellurium, cadmium sulfide, pyrylium, thiopyrylium, azulenium dye, phthalocyanine pigment, anthorone pigment, dibenzpyrenequinone pigment, pyranthrone pigment, trisazo pigment. , disazo pigments, azo pigments, indigo pigments, quinacridone pigments, thiacyanine asymmetric quinocyanine, quinocyanine, or a separate vapor deposited layer or resin dispersion selected from charge generating substances such as amorphous silicon described in JP-A-54-143645. Layers can be used. The charge-generating layer can be formed by dispersing the above-mentioned charge-generating substance in a suitable binder and coating it on the substrate, or by forming a vapor-deposited film using a vacuum evaporator. Obtainable. Binders that can be used to form the charge generating layer by coating can be selected from a wide range of insulating resins, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. You can choose. 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. Examples of organic solvents used during coating 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, 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 in the same manner as for the charge transport layer. The charge generation layer contains as much of the organic photoconductor as possible in order to obtain sufficient absorbance and is preferably a thin film layer, for example less than 5 microns, in order to shorten the range of the generated charge carriers. teeth
A thin film layer having a thickness of 0.01 micron to 1 micron is preferable. 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. 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 (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, Ataryl resin, polyethylene fluoride, etc.) or conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic together with a suitable binder; substrates made of plastic or paper impregnated with conductive particles; For example, plastics containing polymers having a high molecular weight can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing 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. 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 surface level attenuation and creating static between the unexposed area and the exposed 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. According to the present invention, it is possible to provide a highly sensitive electrophotographic photoreceptor, and it is possible to provide a highly sensitive electrophotographic photoreceptor, and it is also possible to provide an electrophotographic photoreceptor that can be repeatedly charged and exposed.
It has the advantage of providing a highly durable electrophotographic photoreceptor with small fluctuations in bright area potential and dark area potential when repeated over 100,000 times. Hereinafter, the present invention will be explained according to examples. Example 1 7 g of a pigment purified by sequentially refluxing β-type copper phthalocyanine (trade name: Lionol Blue NCB Toner) manufactured by Toyo Ink Manufacturing Co., Ltd. in water, ethanol and benzene, and filtering; : Polyester adhesive 49000 (solid content 20%)” 14
A coating solution was prepared by mixing 35 g of toluene and 35 g of dioxane and dispersing the mixture in a ball mill for 6 hours. This coating solution was applied onto an aluminum sheet using a Mayer bar to a dry film thickness of 0.5 microns to form a charge generation layer. Next, the above-mentioned exemplary compound (1) is used as a charge transport compound.
and 7 g of polycarbonate resin (trade name (Panlite K-1300) manufactured by Teijin Kasei Ltd.) were stirred and dissolved in a mixed solvent of 35 g of tetrahydrofuran and 35 g of chlorobenzene. An electrophotographic photoreceptor with a two-layer photosensitive layer was created by coating the top with a Meyer bar to a dry film thickness of 15 microns. Using an electrostatic copying paper tester Model-SP-428 manufactured by Denki Co., Ltd., the sample was statically charged with a corona at -5 kV, held in a dark place for 1 second, and then exposed to light at an illuminance of 5 lux to examine the charging characteristics. As for charging characteristics, we measured the surface potential (V ₀ ) and the exposure amount (E _1/2 ) required to attenuate the potential (V ₁ ) by 1/2 when dark decaying for 1 second. In order to measure the fluctuations in bright area potential and dark area potential during use, the photoreceptor prepared in this example was attached to the photosensitive drum cylinder of a PPC copier NP-105Z manufactured by Canon Inc.
100,000 copies were made, and the fluctuations in the light area potential (V _L ) and the dark area potential (V _D ) at the initial stage and after 100,000 copies were measured. Comparative sample 1 was prepared in the same manner as in Example 1 except that N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole was used in place of the exemplified compound (1). It was measured.
The results are shown below.

[Table] Examples 2 to 12 An ammonia aqueous solution of casein (11.2 g of casein/1 g of 28% ammonia water was placed on an aluminum plate)
The film thickness after drying (dissolved in 222ml) with a Mayer bar is
It was applied to a thickness of 1.0 micron and dried. Next, commercially available disazo pigment Chlorodian Blue 5
g, 3 g of butyral resin manufactured by Sekisui Chemical Co., Ltd. (trade name: ESLETSUKU BM-2), and 3 g of methyl ethyl ketone.
It was added to the solution dissolved in 90 ml and dispersed with an attritor for 2 hours. This dispersion was applied onto the previously formed casein layer using a Mayer bar so that the film thickness after drying would be 0.3 microns, and dried at 50° C. for 10 minutes to form a charge generation layer. Next, exemplified compounds (2), (3), (7), (8), (9), (10),
For (11), (17), (18), (20) and (25), 7gr each was dissolved in 45g of monochlorobenzene, and a film thickness was applied on the charge generation layer by Mayer bar coating in the same manner as in Example 1. A 15 micron charge transport layer was created. The electrophotographic properties of these photoreceptors were measured in the same manner as in Example 1. The results are shown below.

【table】

[Table] Examples 13 to 30 In Example 2, 4-(4-dimethylaminophenyl)-2,6- was used instead of chlorodiane blue.
A charge generation layer having a thickness of 0.3 microns was prepared in the same manner as in Example 2 except that diphenylthiapyrylium perchlorate was used. Next, exemplified compounds (1), (4), (5), (6), (12), (13), (1
Four),
(15), (16), (19), (21), (22), (23) and (24)
7 g of each were dissolved in a toluene:dioxane (40 g:40 g) mixed solvent together with the amounts of P-diethylaminobenzaldehyde-N,N-diphenylhydrazone and Polyester Adhesive 49000 manufactured by DuPont as shown in Table 3. A charge transport layer of 16 microns was formed on the charge generation layer using the same recipe as in Example 1. The electrophotographic properties of these photoreceptors were measured in the same manner as in Example 1. The results are shown in Table 4.

【table】

[Table] *2 Percentage of total solid content

【table】

[Table] Examples 32 to 36 A 0.3 micron charge generation layer was prepared by using a disazo pigment having the following structure in place of the chlorodiampule used in Example 2. On the charge generating layer, 5 g of 2,4,7-trinitro-9-fluorenone, 5 g of poly-4,4'-dioxydiphenyl-2,2'-propane carbonate (molecular weight 300,000) and the exemplified compound ( 26),
A coating solution was prepared by dissolving 5 g each of (1), (27), (28), and (29) in 80 ml of tetrahydrofuran. On the other hand, as a comparative sample, a compound having the same structure as Exemplified Compound (1) and n number of 0 was synthesized in advance, and a coating liquid was prepared in the same manner as above. These coating solutions were applied and dried so that the coating amount after drying was 10 g/m ² . The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the settings of the electrostatic copying paper tester were changed so that the charging polarity was as follows, and the NP-150Z was modified. The results are shown in Table 5.

[Table] Example 37 4-(4-dimethylaminophenyl)-2,6-
After fully dissolving 3 g of diphenylthiapyrylium perchlorate and 3 g of poly(4,4'-isopropylidene diphnylene carbonate) in 200 ml of dichloromethane, 100 ml of toluene was added to precipitate a eutectic complex. After separating this precipitate, dichloromethane was added to redissolve it, and then this solution was added with n-
100 ml of hexane was added to obtain a precipitate of the eutectic complex. 5 g of the above eutectic complex and 5 g of exemplified compound (26) were added to polyester (polyester adhesive).
49000: Dupont) tetrahydrofuran solution
The mixture was added to 150 ml and thoroughly mixed and stirred. This liquid was applied onto an aluminum sheet using a Mayer bar so that the film thickness after drying was 15 μm. The electrophotographic properties of this photoreceptor were measured in the same manner as in Example 1. The results are shown below. V ₀ : -610 volts V ₁ : -595 volts E _1/2 : 3.9lux.sec Initial V _D : -705 volts V _L : -70 volts After 100,000 sheets endurance V _D : -665 volts V _L : -110 bolt.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor characterized by having a photosensitive layer containing a compound represented by the following general formula or as a photoconductive substance: [In the formula, R ₁ represents a hydrogen atom or an alkyl group, an aryl group, or an aralkyl group that may have a substituent,
R ₂ represents a hydrogen atom or an alkyl group, and X ₁ and X ₂
each represents a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group, or a halogen atom;
Ar ₁ −CH=CH− or Ar ₁ −CH=CH−Ar ₂
- (where Ar ₁ and Ar ₂ each represent an aromatic ring or a heterocycle which may have a substituent), and n is an integer of 1 or more].