JPH0627699A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To select a specified electric charge transferring material satisfying such electrophotographic characteristics as sensitivity, potential retentivity, potential stability and residual potential with high performance in an electrophotographic sensitive body using a specified bisazo pigment. CONSTITUTION:A photosensitive layer contg. a bisazo pigment represented by formula I [where A is a residue of a coupler, R1 is H, aryl, etc., and (n) is 0 or 1] as an electric charge generating material and a compd. represented by formula II [where each of Ar1-Ar4 is H or aryl but all of them are not H and (n) is 0 or 1] as an electric charge transferring material is formed on an electric conductive substrate.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus using an electrophotographic method such as an electrostatic copying machine and a laser beam printer.

2. Description of the Related Art The electrophotographic method such as the Carlson process is a step of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge, and exposing the charged surface of the electrophotographic photosensitive member to an electrostatic latent image on the surface. An exposure step of forming an image, a developing step of bringing a developer into contact with the formed electrostatic latent image, and developing the electrostatic latent image into a toner image by toner contained in the developer, and a toner image Transfer step of transferring the toner to paper, a fixing step of fixing the transferred toner image, and a transfer step,
And a cleaning step for removing the toner remaining on the photoconductor. As an electrophotographic photosensitive member used in the electrophotographic method, one using a specific bisazo pigment is known. (See JP-A 1-2202757).

By the way, in order to prepare an organic photoreceptor using a charge generating material and a charge transporting material, electrophotographic characteristics such as sensitivity, potential holding property, potential stability and residual potential are satisfied. In order to do so, materials with good matching must be selected. For example, no matter how much charge-generating material generates sufficient charge, satisfactory electrophotographic characteristics cannot be obtained unless it is combined with a charge-transporting material capable of efficiently injecting and transporting the charge. . JP-A-1-202757 discloses that a photosensitive member stable to heat and light can be obtained by using the general formula (1) and various carrier-moving substances. However, the charge-generating material disclosed in the above publication has a phthalocyanine-based or perylene-based pigment, a fluorenone-type bisazo pigment (JP-A-57-96345), and a perinone skeleton, which are commonly used charge-generating materials. Ozone and nitrogen oxide NO generated in the copying machine as compared with oxadiazole type azo pigments having a coupler (Japanese Patent Laid-Open No. 229564/1984)
It has a drawback that it is apt to be oxidized and deteriorated by x, light and the like, and the characteristics of the photoreceptor are likely to be deteriorated. It is presumed that such oxidative deterioration of the pisazo pigment (1) occurs because ozone or the like adsorbs to the azo group and decomposes the azo group. Such oxidative deterioration is promoted when the above bisazo pigment (1) is used in combination with a charge transport material which is an electron donating compound. This is because if the electron-donating compound has a strong basicity, the electron-donating substance coordinates with the azo group and increases the electron density of the azo group, which makes it more likely to be attacked by ozone and nitrogen oxides. To be Moreover, even if the carrier transfer material exemplified in the above publication is used, a photoreceptor having high sensitivity and repeatability cannot be obtained without impairing the excellent characteristics of the bisazo pigment (1). , I am still not fully satisfied. Therefore, the object of the present invention has been made in view of the above circumstances, and is required as an electrophotographic photosensitive member in the electrophotographic photosensitive member using the bisazo pigment represented by the general formula (1). It is to select a charge transport material that satisfies all the requirements with high performance.

Therefore, the inventors of the present invention selected a specific charge transporting material for the bisazo pigment to obtain electrophotographic characteristics satisfying high performance, and used it. As a result of various studies on the charge transport material, the following general formula (1) as a charge generating material on the conductive substrate:

[Chemical 3] (In the formula, A is the same or different and represents a coupler residue, R 1 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. The alkyl group, the aryl group, and the heterocyclic group represent a substituent. Bisazo pigment represented by the following general formula (2) as a charge transport material:

[Chemical 4] (In the formula, Ar1, Ar2, Ar3, and Ar4 are the same or different and each represents a hydrogen atom or an aryl group which may have a substituent, and n represents an integer of 0 to 1. However, Ar1, Ar2, A
Except when all of r3 and Ar4 are hydrogen atoms. It was found that a photosensitive layer containing a compound represented by the formula (4) should be provided, and the present invention has been completed. Although the effect of the selection of the specific charge transporting material of the present invention is not clear, it is understood from the comparison between the examples and the comparative examples described later that the sensitivity is remarkably improved. In other words, it is assumed that problems such as fog do not occur even if the output of the exposure lamp that is standardly installed in the copying machine is not increased, which leads to a longer life of the exposure lamp and a reduction in power consumption. To be done.

Preferred Embodiments Charge Generating Material In the bisazo pigment represented by the general formula (1), the alkyl group corresponding to the group R1 in the formula is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group or a butyl group, Examples thereof include an isobutyl group, a t-butyl group, a pentyl group and a hexyl group. Examples of the aryl group include a phenyl group, an o-terphenyl group, a naphthyl group, an anthryl group,
Examples of the heterocyclic group include a phenanthryl group and the like.
For example, thienyl group, pyrrolyl group, pyrrolidinyl group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, 2H-imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group,
Examples thereof include pyranyl group, pyridyl group, piperidyl group, piperidino group, 3-morpholinyl group, morpholino group and thiazolyl group. It may also be a heterocyclic group condensed with an aromatic ring. The substituent to be substituted on the above group,
For example, a halogen atom, an amino group, a hydroxyl group, a carboxyl group which may be esterified, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 2 to 2 carbon atoms. And the alkenyl group of 6 and the like. Examples of the coupler residue represented by A include groups represented by general formulas (a) to (g).

[Chemical 5] In each formula, R ³⁰ represents a carbamoyl group, a sulfamoyl group, an allofanoyl group, an oxamoyl group, an anthraniloyl group, a carbazoyl group, a glycyl group, a hydantoyl group, a phthalamoyl group, and a succinamoyl group.
These groups include halogen atoms, phenyl groups which may have a substituent, naphthyl groups which may have a substituent, nitro groups, cyano groups, alkyl groups, alkenyl groups, carbonyl groups, carboxyl groups and the like. It may have a group. R
³¹ represents an atomic group necessary for forming an aromatic ring, a polycyclic hydrocarbon or a heterocycle by being condensed with the above R ³⁰ and a benzene ring having a hydroxyl group, and these rings are the same substituents as described above. May have. R ³² represents an oxygen atom, a sulfur atom or an imino group. R ³³ represents a divalent chain hydrocarbon or aromatic hydrocarbon, and these groups may have the same substituents as described above. R ³⁴ represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group, and these groups may have the same substituents as described above. R ³⁵ is a divalent chain hydrocarbon, an aromatic hydrocarbon, or the following formula (h) in the above general formulas (e) and (f).

[Chemical 6] Represents a group of atoms necessary to form a heterocycle with the moiety represented by, and these rings may have the same substituents as described above. R ³⁶ is a hydrogen atom, an alkyl group, an amino group, a carbamoyl group, a sulfamoyl group, an allofanoyl group,
It represents a carboxyl group, an ester of a carboxyl group, an aryl group, or a cyano group, and groups other than a hydrogen atom may have the same substituents as described above. R ³⁷ represents an alkyl group or an aryl group, and these groups may have the same substituents as described above. Examples of the alkyl group include lower alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group and hexyl group. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. In R ³¹ , the atomic group necessary for forming an aromatic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group is, for example, an alkylene group such as a methylene group, an ethylene group, a propylene group or a butylene group. To be Examples of the aromatic ring formed by condensation of R ³¹ and R ³⁰ and a benzene ring having a hydroxyl group include naphthalene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, and naphthacene ring. In R ³¹ , the atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a polycyclic hydrocarbon is, for example, a methylene group, an ethylene group, a propylene group, a butylene group, or a carbon atom. Examples include alkylene groups of the numbers 1 to 4. In R ³¹ , the polycyclic hydrocarbon condensed with R ³⁰ and a benzene ring having a hydroxyl group includes, for example, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring and the like. Further, in R ³¹ , the atomic group necessary for forming a heterocycle by condensing with R ³⁰ and a benzene ring having a hydroxyl group is, for example, a benzofuranyl group, a benzothiophenyl group,
Indolyl group, 1H-indolyl group, benzoxazolyl group, benzothiazolyl group, 1H-indaryl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazolinyl group, quinoxalinyl group Group, dibenzofuranyl group, carbazolyl group,
Examples thereof include a xanthenyl group, an acridinyl group, a phenanthridinyl group, a phenazinyl group, a phenoxazinyl group and a thianthrenyl group. Examples of the aromatic heterocyclic group formed by condensing R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group include a thienyl group, a furyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group and an isothiazolyl group. , Imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group,
Examples thereof include thiazolyl group. It may also be a heterocyclic group condensed with another aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group). Said R ³³ ,
In R ³⁵ , examples of the divalent chain hydrocarbon include ethylene group, propylene group and butylene group, and examples of the divalent aromatic hydrocarbon include phenylene group, naphthylene group,
Examples thereof include a phenanthrylene group. Examples of the heterocyclic group for R ³⁴ include a pyridyl group, a pyrazyl group, a thienyl group, a pyranyl group and an indolyl group. Examples of the atomic group necessary for forming a heterocycle in the R ³⁵ together with the moiety represented by the formula (h) include a phenylene group, a naphthylene group, a phenanthrylene group, an ethylene group, a propylene group, and a butylene group. can give. Examples of the aromatic heterocyclic group formed by R ³⁵ and the moiety represented by the formula (h) include, for example, benzimidazole group, benzo [f] benzimidazole group, dibenzo [e, g] benzimidazole group. Group, benzopyrimidine group and the like. These groups may have the same substituents as described above. In R ³⁶ , examples of the carboxyl group ester include methyl ester, ethyl ester, propyl ester, butyl ester and the like. Specific examples of the coupler residue A represented by the above general formulas (a) to (g) include the following groups.

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10] Specific examples of the azo compounds include compounds represented by the following formulas (B1) to (B10).

[Chemical 11]

[Chemical 12]

[Chemical 13] As the charge generating material, in addition to the pigment represented by the general formula (1), for the purpose of expanding the sensitivity region of the electrophotographic photosensitive member so as to have an absorption wavelength region in a desired region, Also, other conventionally known charge generating materials can be used together. Other charge generating materials include selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo pigments other than those represented by the general formula (1), perylene pigments, anthanthrone pigments, Examples thereof include phthalocyanine pigments, indigo pigments, triphenylmethane pigments, slene pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, and pyrrolopyrrole pigments. Charge Transport Material In the compound represented by the general formula (2), A in the formula
Examples of the aryl group corresponding to r1 to Ar4 include the same groups as those represented by the general formula (1). Further, as the substituent for substituting the aryl group and the like, for example, the same groups as those represented by the general formula (1) can be mentioned. Specific examples of the compound represented by the general formula (2) include compounds represented by the following formulas (A1) to (A20).

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17] The compound represented by the general formula (2), which is a charge transport material, can be used alone or in combination with other conventionally known charge transport materials. As the conventionally known charge transport material, various electron-withdrawing compounds and electron-donating compounds can be used. As the electron-withdrawing compounds, e.g., ^{2,6-dimethyl-2,, 6,} - di ter
diphenoquinone derivatives such as t-dibutyldiphenoquinone, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone,
Examples include 3,4,5,7-tetranitro-9-fluorenone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride and dibromomaleic anhydride. Further, as the electron-donating compound, 2,5-di (4-methylaminophenyl), 1,
Oxadiazole compounds such as 3,4-oxadiazole, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, 1-phenyl-3- (p-dimethylaminophenyl) ) Pyrazoline compounds such as pyrazoline, hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds Nitrogen-containing cyclic compounds such as
Fused polycyclic compounds are illustrated. These charge transport materials are used alone or in combination of two or more. When using a charge transport material having film-forming properties such as polyvinylcarbazole, the binder resin is not always necessary. Binder Resin Various resins can be used as the binder resin. For example, styrene-based polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer , Chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, Thermoplastic resin such as polyester resin, silicone resin, epoxy resin,
Examples thereof include phenol resins, urea resins, melamine resins, other crosslinkable thermosetting resins, and photocurable resins such as epoxy acrylate and urethane-acrylate.
These binder resins can be used alone or in combination of two or more. Additives The organic photosensitive layer may contain additives such as a sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and a plasticizer. Examples of the antioxidant include compounds represented by the following formulas (e1), (e2) and (e3).

[Chemical 18] (In the formula, a, b and d represent a hydrogen atom and a monovalent organic residue, E1, E2, E3 and E4 represent a hydrogen atom and an alkyl group, and E5 and E6 represent a hydrogen atom, a halogen atom and an alkyl group. , Indicates a hydroxyl group.)

[Chemical 19] (In the formula, E7, E8, E9, E10, and E11 represent a hydrogen atom, a halogen atom, a hydroxyl group, or an alkyl group which may have a substituent.)

[Chemical 20] (In the formula, e and f are alkylene groups, E12, E13,
E14 and E15 represent a hydrogen atom or an alkyl group,
16 represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and r represents an integer of 3 to 40. In addition, in order to improve the sensitivity of the charge generation layer, known sensitizers such as terphenyl, halonaphthoquinones and acenaphthylene may be used in combination with the charge generation material. As the conductive substrate on which the organic photosensitive layer is formed, various conductive materials can be used, such as aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium and titanium. , Single metal such as nickel, palladium, indium, stainless steel, brass,
Examples include a plastic material obtained by vapor deposition or laminating of the above metal, glass coated with aluminum iodide, tin oxide, indium oxide, or the like. The conductive substrate may be in the form of a sheet, a drum, or the like, and the substrate itself may be conductive, or the surface of the substrate may be conductive. Further, it is preferable that the conductive substrate has sufficient mechanical strength when used. Structure of Photoreceptor The photoconductor of the present invention can be applied to either a single layer type or a laminated type as a photosensitive layer. However, since the effect of the combination of the charge generating material and the charge transporting material becomes more remarkable especially in the single layer type photosensitive layer in which both materials are contained in the same layer, the present invention provides a single layer type photosensitive layer. It can be said that it is more preferable to apply to an electrophotographic photosensitive member having a layer. In order to obtain a single-layer type photoreceptor, the above-mentioned general formula (1) which is a charge generating material is used.
When a photosensitive layer containing a compound represented by the formula (1), a compound represented by the general formula (2) which is a charge transporting material, and a binder resin is formed on a conductive substrate by a means such as coating. Good. In order to obtain a laminated type photoreceptor, a charge generation layer containing the pigment represented by the general formula (1) is formed on a conductive substrate by means such as vapor deposition or coating. A charge transport layer containing the compound represented by the general formula (2) and a binder resin may be formed thereon. Also,
Conversely, the charge transport layer may be formed on the conductive substrate, and then the charge generation layer may be formed. In the laminated photoreceptor, the charge generating material and the binder resin which form the charge generating layer can be used in various ratios.
Charge generation material 5 to 00 parts (parts by weight, the same applies hereinafter)
It is preferably used in an amount of ˜1000 parts, especially 30 to 500 parts. The charge transport material constituting the charge transport layer and the binder resin can be used in various proportions within a range that does not inhibit charge transport and a range that does not crystallize,
In order to easily transport the charges generated in the charge generation layer by light irradiation, the charge transport material 1 is added to 100 parts of the binder resin.
It is preferably used in a proportion of 0 to 500 parts, particularly 25 to 200 parts. The thickness of the laminated photosensitive layer is preferably about 0.01 to 5 μm, particularly 0.1 to 3 μm for the charge generation layer, and 2 to 100 μm for the charge transport layer.
It is particularly preferable that the thickness is about 5 to 50 μm. In the single-layer type photoreceptor, the charge generating material is 0.1 to 50 parts, particularly 0.5 to 30 parts, and the charge transporting material is 20 to 200 parts, especially 30 to 150 parts, relative to 100 parts of the binder resin. Is appropriate. The thickness of the single-layer type photosensitive layer is 5 to 1
The thickness is preferably 00 μm, particularly preferably 10 to 50 μm. In the case of a single-layer type photoreceptor, it is between the conductive base and the photosensitive layer, and in the case of the multilayer type photoreceptor, it is between the conductive base and the charge generating layer, and between the conductive base and the charge transport layer. A barrier layer may be formed between the layers or between the charge generation layer and the charge transport layer as long as the characteristics of the photoreceptor are not impaired, and a protective layer is formed on the surface of the photoreceptor. May be. Preparation of Photoreceptor When forming each of the above layers by a coating method, the charge generation material, charge transport material, binder resin and the like exemplified above, together with a suitable solvent, in a known method, for example, a roll mill,
Prepare a coating solution by dispersing and mixing with a ball mill, attritor, paint shaker or ultrasonic disperser.
This may be applied and dried by a known means. As the solvent for forming the coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, benzene, Aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone, etc. Examples thereof include ketones, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like.
These solvents can be used alone or in combination of two or more. Furthermore, in order to improve the dispersibility of the charge transport material and the charge generating material and the smoothness of the photosensitive layer surface, a surfactant,
A leveling agent or the like may be used. Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Examples 1 to 6 and Comparative Examples 1 to 6 (multilayer type photoreceptor) 1 part of the charge generating material, 1 part of polyvinyl butyral resin, and a predetermined amount of tetrahydrofuran were mixed in a paint shaker using glass beads (2 mm diameter). Dispersed for 2 hours. The obtained dispersion liquid was applied to the surface of an aluminum sheet as a conductive substrate by a bar coating method using a wire bar and dried at 100 ° C. for 1 hour to form a charge generation layer having a thickness of 0.5 μm. . The charge generation materials used are shown in Tables 1 and 2 as specific examples (B1) to
The numbers are shown using the compound number of (B10). A solution prepared by dissolving 1 part of the charge transport material and 1 part of bisphenol A type polycarbonate resin in a predetermined amount of dichloromethane was applied onto the charge generation layer by a bar coating method using a wire bar, and dried at 100 ° C. for 1 hour. Then, a charge transport layer having a film thickness of 22 μm was formed to obtain a negative charging type laminated electrophotographic photoreceptor. The charge transporting materials used are the compound numbers of the specific examples (A1) to (A20) described above for the examples, and the compound numbers of the following formulas (D1) to (D11) for the comparative examples. It was shown to.

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23] Examples 7 to 12 and Comparative Examples 7 to 12 (single layer type photoreceptor) 10 parts of charge generating material, 75 parts of charge transporting material, 100 parts of bisphenol A type polycarbonate resin, together with a predetermined amount of dichloromethane, a paint shaker. Was dispersed for 2 hours to prepare a coating liquid for a single-layer type photosensitive layer. Then, this coating solution is applied to the surface of an aluminum sheet as a conductive substrate by a bar coating method using a wire bar and dried at 100 ° C. for 1 hour to give a film thickness of 2
A single layer type photosensitive layer having a thickness of 5 to 30 μm was formed to obtain a positive charging type single layer type electrophotographic photosensitive member. The charge generation material used is
In Tables 1 and 2, the above-mentioned specific examples (B1) to (B1
The charge transporting materials used in the examples are shown in the above specific examples (A1) to (0).
Regarding the compound numbers of (A20) and Comparative Examples, the following formula (D
The numbers are shown using the compound numbers 1) to (D11). The following tests were carried out on the electrophotographic photoreceptors of the above-mentioned respective Examples and Comparative Examples, and their characteristics were evaluated. Electric characteristics By adjusting the flow-in current value by an electrostatic copying tester (Gentec Cynthia 30M manufactured by Gentec), the surface of the sheet-shaped electrophotographic photosensitive member prepared in Examples and Comparative Examples is adjusted to about ± 800V. After measuring the initial surface potential (V) at the time of charging, the most necessary 55 for the photoconductor for PPC.
The half-exposure amount was measured using 0 nm light. That is,
550n taken out from the xenon lamp using a spectrometer
m light was exposed with an intensity of 0.2 mW / cm ² and an exposure time of 1 second to obtain a half-exposure amount (μJ / cm ² ). Further, the surface potential at the time point when 0.5 seconds passed immediately after the exposure was determined as the post-exposure potential (V). Repetitive characteristics The electrophotographic photoreceptors obtained in each of the above Examples and Comparative Examples,
After sticking on each of the aluminum cylinders using an adhesive tape, they were mounted on an electrostatic copying machine DC-1670M (manufactured by Mita Industry Co., Ltd.). Next, copying was repeated 10,000 times, and then the surface potential (V) and the half-exposure amount (μ
J / cm ² ) and the potential (V) after exposure were measured. The above results are shown in Tables 1 and 2.

[Table 1]

[Table 2] As is clear from Tables 1 and 2, the electrophotographic photosensitive members of the present invention represented by Examples 1 to 12 are excellent in post-exposure potential, half-exposure amount and repetitive characteristics. It can be seen that the characteristics show high performance. On the other hand, the electrophotographic photosensitive members represented by Comparative Examples 1 to 12 had high post-exposure potential and poor sensitivity. Therefore, fog has occurred from the beginning of copying, and even if the exposure lamp, which is standardly installed in the electrostatic copying machine, outputs at maximum, the potential corresponding to the white background is high and fog occurs. Further, as is clear from Table 2, the electrophotographic photosensitive members of Comparative Examples 1, 4, 6, 7, 8, and 12 had extremely lowered surface potentials due to repeated use. Therefore, in the image confirmation after repeated copying, the contrast potential was reduced and the image density was also reduced.

According to the present invention, by selecting the compound represented by the general formula (2) as the charge transporting material, the azo pigment represented by the general formula (1) as the charge generating material is selected. It was possible to provide an organic photoreceptor having excellent electrophotographic characteristics.

Claims (1)

[Claims] 1. The following general formula (1) as a charge generating material on a conductive substrate: (In the formula, A is the same or different and represents a coupler residue, R 1 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. The alkyl group, the aryl group, and the heterocyclic group represent a substituent. Bisazo pigment represented by the following general formula (2) as a charge transporting material: (In the formula, Ar1, Ar2, Ar3, and Ar4 are the same or different and each represents a hydrogen atom or an aryl group which may have a substituent, and n represents an integer of 0 to 1. However, Ar1, Ar2, A
Except when all of r3 and Ar4 are hydrogen atoms. An electrophotographic photosensitive member comprising a photosensitive layer containing a compound represented by the formula (1).