JP3105359B2 - Electrophotographic photoreceptor - Google Patents

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 utilizing an electrophotographic method, such as an electrostatic copying machine or a laser beam printer.

2. Description of the Related Art An electrophotographic method such as the Carlson process includes a step of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge, and a step of exposing the charged surface of the electrophotographic photosensitive member to an electrostatic latent image. 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 with toner contained in the developer; And a fixing step of fixing the transferred toner image, and after the transfer step,
A cleaning step of removing toner remaining on the photoconductor. As an electrophotographic photoreceptor used in the above electrophotographic method, one using a specific bisazo pigment is known. (See Japanese Patent Application Laid-Open No. 1-220257).

By the way, in order to prepare an organic photoreceptor using a charge generation material and a charge transport material, it is necessary to satisfy electrophotographic characteristics such as sensitivity, potential holding property, potential stability and residual potential. In order to do so, it is necessary to select materials with good matching. For example, no matter how much a charge generating material generates a sufficient charge, satisfactory electrophotographic characteristics cannot be obtained unless the charge is efficiently combined with a charge transporting material capable of transporting the charge. . According to Japanese Patent Application Laid-Open No. Hei 1-220257, it is disclosed that a photoconductor stable against heat and light can be obtained by using the general formula (1) and various carrier transfer materials. However, the charge generating materials disclosed in the above-mentioned publications include phthalocyanine-based and perylene-based pigments, fluorenone-type bisazo pigments (JP-A-57-96345), which are commonly used charge generating materials, and a perinone skeleton. Ozone and nitrogen oxide NO generated in a copying machine are compared with oxadiazole type azo pigments having a coupled coupler (JP-A-59-229564).
There is a disadvantage that it is easily oxidized and degraded by x, light, and the like, and is likely to cause deterioration of the photoreceptor characteristics. It is presumed that such oxidative deterioration of the pisazo pigment (1) occurs because ozone or the like is adsorbed on the azo group to decompose the azo group. Such oxidative deterioration is accelerated when the bisazo pigment (1) is used in combination with a charge transporting material that is an electron donating compound. This is because when the electron donating compound has a strong basicity, the electron donating substance coordinates to the azo group and increases the electron density of the azo group, which makes it more susceptible to attack by ozone and nitrogen oxides. Can be Moreover, even if the carrier transfer material exemplified in the above-mentioned publication is used, a photoconductor having high sensitivity and repetition characteristics cannot be obtained without impairing the excellent characteristics of the bisazo pigment (1). Is 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 an electrophotographic photosensitive member using the bisazo pigment represented by the general formula (1). The object is to select a charge transport material that satisfies all of the requirements with high performance.

Accordingly, the present inventors have selected a specific charge transport material for the above bisazo pigment and intended to obtain high performance and satisfactory electrophotographic properties. As a result of various studies on the charge transporting material, the following general formula (1) as a charge generating material on a conductive substrate:

Embedded image (Wherein, A represents the same or different coupler residue, R1 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. And n represents 0 or 1.) and a charge transporting material represented by the following general formula (2):

Embedded image (Wherein R2, R3, R4 and R5 are the same or different and represent an alkyl group, an aryl group, or an aralkyl group;
Ar1 and Ar2 are the same or different and represent an arylene group. The alkyl group, aryl group, aralkyl group, and arylene group may have a substituent. It has been found that a photosensitive layer containing the compound represented by the formula (1) may be provided, and the present invention has been completed. The effect of the selection of the specific charge transporting material of the present invention has not been clarified, but it is understood from the comparison of Examples and Comparative Examples described later that the sensitivity is significantly improved as a result. In other words, even if the output of the exposure lamp, which is mounted as a standard in the copier, is not increased, fogging and other problems do not occur, which is expected to lead to a longer life of the exposure lamp and a reduction in power consumption. Is done.

In PREFERRED EMBODIMENTS bisazo pigment represented by the charge generating material Formula (1), the alkyl group corresponding to group R1 in the formula, such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, Examples 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,
Phenanthryl group and the like, and as the heterocyclic group,
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 include a pyranyl group, a pyridyl group, a piberidyl group, a piperidino group, a 3-morpholinyl group, a morpholino group, and a thiazolyl group. Further, it may be a heterocyclic group condensed with an aromatic ring. As the substituent for 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, and 2 to 2 carbon atoms which may have an aryl group And 6 alkenyl groups. Examples of the coupler residue represented by A include groups represented by general formulas (a) to (g).

Embedded image 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 a halogen atom, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a nitro group, a cyano group, an alkyl group, an alkenyl group, a carbonyl group and a carboxyl group. It may have a group. R
³¹ represents an atomic group necessary for forming an aromatic ring, a polycyclic hydrocarbon or a heterocyclic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group, and these rings are the same as those described above. May be provided. R ³² represents an oxygen atom, a sulfur atom, or an imino group. R ³³ represents a divalent chain hydrocarbon or an aromatic hydrocarbon, and these groups may have the same substituent 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 substituent 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).

Embedded image Represents an atomic group necessary for forming a heterocyclic ring together with the moiety represented by, and these rings may have the same substituent as described above. R ³⁶ represents a hydrogen atom, an alkyl group, an amino group, a carbamoyl group, a sulfamoyl group, an allophanoyl group,
It represents a carboxyl group, an ester of a carboxyl group, an aryl group, or a cyano group, and a group other than a hydrogen atom may have the same substituent as described above. R ³⁷ represents an alkyl group or an aryl group, and these groups may have the same substituent as described above. Examples of the alkyl group include a lower alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, and a 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 , examples of the atomic group necessary for forming an aromatic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group include an alkylene group such as a methylene group, an ethylene group, a propylene group, and a butylene group. Can be Examples of the aromatic ring formed by condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group include a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, and a naphthacene ring. In R ³¹ , an atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a polycyclic hydrocarbon includes, for example, carbon atoms such as a methylene group, an ethylene group, a propylene group, and a butylene group. Examples include alkylene groups of the formulas 1 to 4. Examples of the polycyclic hydrocarbon condensed with R ³⁰ and a benzene ring having a hydroxyl group in R ³¹ include, for example, a carbazole ring, a benzocarbazole ring, and a dibenzofuran ring. In R ³¹ , an atomic group necessary for forming a heterocyclic ring by condensing with R ³⁰ and a benzene ring having a hydroxyl group includes, for example, a benzofuranyl group, a benzothiophenyl group,
Indolyl group, 1H-indolyl group, benzoxazolyl group, benzothiazolyl group, 1H-indolyl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonyril group, quinoxalinyl 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 condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group include, for example, thienyl group, furyl group, pyrrolyl group, oxazolyl group, isoxazolyl group, thiazolyl group, and isothiazolyl group. , Imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group,
And thiazolyl groups. Further, it may 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, etc.). R ³³ ,
In R ³⁵ , examples of the divalent chain hydrocarbon include an ethylene group, a propylene group, and a butylene group. Examples of the divalent aromatic hydrocarbon include a phenylene group, a naphthylene group,
A phenanthrylene group and the like. In the R ^34, examples of the heterocyclic group, a pyridyl group, pyrazinyl group, thienyl group, pyranyl group, indolyl group and the like. In R ³⁵ , examples of the atomic group necessary for forming a heterocyclic ring 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 a benzimidazole group, a benzo [f] benzimidazole group, and a dibenzo [e, g] benzimidazole And benzopyrimidine groups. These groups may have the same substituents as described above. In the R ^36, the ester of a carboxyl group, a methyl ester, ethyl ester, propyl ester, butyl ester, and the like. Specific examples of the coupler residue A represented by the general formulas (a) to (g) include the following groups.

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Embedded image Specific examples of the azo compound include compounds represented by the following formulas (B1) to (B10).

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Embedded image In addition, 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 photoreceptor so as to have an absorption wavelength region in a desired region, the charge generation material is further added. Alternatively, other known charge generation materials may be used in combination. As other charge generating materials, selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salt, azo pigments other than those represented by the general formula (1), perylene pigments, ansanceron pigments, Examples include phthalocyanine pigments, indigo pigments, triphenylmethane pigments, sulene pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, and pyrrolopyrrole pigments. Charge transport material In the compound represented by the general formula (2), R in the formula
Examples of the alkyl group and the aryl group corresponding to 2 to R4 include the same groups as the groups represented by the general formula (1). Examples of the aralkyl group include a benzyl group, an α-phenethyl group, a β-phenethyl group, a 3-phenylpropyl group, a benzhydryl group, and a trityl group. Examples of the arylene group include a phenylene group, an o-terphenylene group, a naphthylene group, an anthrylene group, and a phenanthrylene group. Examples of the substituent for the alkyl group or the like include, for example, those similar to the group represented by the general formula (1). The general formula (2)
Specific examples of the compound represented by are, for example, those represented by the following formulas (A1) to (A17).

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Embedded image The compound represented by the general formula (2), which is a charge transport material, can be used alone or in combination with another conventionally known charge transport material. As a conventionally known charge transporting 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-dibutyl diphenoquinone, malononitrile, thiopyran-based compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone,
Examples thereof include 3,4,5,7-tetranitro-9-fluorenone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of the electron donating compound include 2,5-di (4-methylaminophenyl),
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 exemplified. These charge transport materials are used alone or in combination of two or more. When a charge transporting material having a film forming property such as polyvinyl carbazole is used, a binder resin is not necessarily required. Examples of the binder resin a binder resin, can be used various resins. For example, styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic copolymers, styrene-acrylic acid copolymers, 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 include phenolic resins, urea resins, melamine resins, other thermosetting resins having a cross-linking property, and photo-curing 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).

Embedded image (Where a, b and d each represent a hydrogen atom or a monovalent organic residue, E1, E2, E3 and E4 each represent a hydrogen atom or an alkyl group, and E5 and E6 each represent a hydrogen atom, a halogen atom or an alkyl group , Represents a hydroxyl group.)

Embedded image (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.)

Embedded image (Wherein, e and f are alkylene groups, E12, E13,
E14 and E15 each 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. ) Also, in order to improve the sensitivity of the charge generation layer, for example, terphenyl,
Known sensitizers such as halonaphthoquinones and acenaphthylene may be used in combination with the charge generating material. Conductive Substrate As the conductive substrate on which the organic photosensitive layer is formed, various materials having conductivity can be used, for example, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium , Nickel, palladium, indium, stainless steel, brass and other simple metals,
Examples of the material include a plastic material on which the above metal is deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide, and the like. The conductive substrate may be in the form of a sheet, a drum, or the like, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. In addition, the conductive substrate preferably has sufficient mechanical strength when used. Configuration of Photoreceptor The photoreceptor of the present invention can be applied to a single-layer type or a multilayer type as a photosensitive layer. However, the effect of the combination of the charge generation material and the charge transport material is more remarkable in a single-layer photosensitive layer in which both materials are contained in the same layer. It can be said that application to an electrophotographic photoreceptor having a layer is more preferable. In order to obtain a single-layer type photoreceptor, the charge-generating material represented by the general formula (1)
And a photosensitive layer containing a compound represented by the general formula (2), which is a charge transport material, a binder resin and the like, is formed on a conductive substrate by means such as coating. Good. In order to obtain a laminated 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, a charge transport layer may be formed on a conductive substrate, and then a charge generation layer may be formed. In the laminated photoreceptor, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios.
00 parts (parts by weight, the same applies hereinafter) to the charge generation material 5
Preferably, it is used in a proportion of up to 1000 parts, especially 30 to 500 parts. The charge transport material and the binder resin constituting the charge transport layer can be used in various ratios in a range that does not hinder charge transport and a range that does not crystallize,
The charge transporting material 1 is added to 100 parts of the binder resin so that the charges generated in the charge generation layer by light irradiation can be easily transported.
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 such that the charge generation layer is formed to have a thickness of about 0.01 to 5 μm, particularly about 0.1 to 3 μm, and the charge transport layer has a thickness of 2 to 100 μm.
In particular, it is preferably formed to a thickness of about 5 to 50 μm. In the single-layer type photoreceptor, the charge generation material is 0.1 to 50 parts, particularly 0.5 to 30 parts, and the charge transport material is 20 to 200 parts, particularly 30 to 150 parts, based on 100 parts of the binder resin. Is appropriate. The thickness of the single-layer type photosensitive layer is 5-1.
It is preferably formed to a thickness of about 00 μm, especially about 10 to 50 μm. In the case of a single layer type photoreceptor, between the conductive substrate and the photosensitive layer, and in the case of the laminated type photoreceptor, between the conductive substrate and the charge generation layer, or between the conductive substrate and the charge transport. A barrier layer may be formed between the charge transport layer and the charge generation layer or between the charge transport layer and the charge transport layer as long as the properties of the photoreceptor are not impaired. You may. Preparation of the photoreceptor When the above layers are formed by a coating method, the above-described examples of the charge generation material, the charge transport material, the binder resin and the like, together with a suitable solvent, a known method, for example, a roll mill,
Disperse and mix using a ball mill, attritor, paint shaker or ultrasonic disperser to adjust the coating solution,
This may be applied and dried by known means. As a solvent for preparing the coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, n-hexane, octane, cyclohexane, aliphatic hydrocarbons such as 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. 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. Further, in order to improve the dispersibility of the charge transporting 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 (laminated photoreceptor) 1 part of a charge generating material, 1 part of a polyvinyl butyral resin, and a predetermined amount of tetrahydrofuran were mixed with a paint shaker using glass beads (2 mm in diameter). Dispersed for 2 hours. The obtained dispersion 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 above as specific examples (B1) to (B1).
This is shown using the compound number of (B10). A solution prepared by dissolving 1 part of a charge transport material and 1 part of a bisphenol A-type polycarbonate resin in a predetermined amount of dichloromethane is coated on the charge generation layer by a bar coating method using a wire bar, and dried at 100 ° C. for 1 hour. Then, a charge transporting layer having a thickness of 22 μm was formed to obtain a negatively charged laminated electrophotographic photosensitive member. The charge transport materials used are shown in Tables 1 and 2 using the compound numbers of the specific examples (A1) to (A17) described above for the examples and the compound numbers of the following formulas (D1) to (D11) for the comparative examples. It was shown to.

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Embedded image Examples 7 to 12 and Comparative Examples 7 to 12 (Single-layer type photoreceptor) A paint shaker was prepared by charging 10 parts of a charge generating material, 75 parts of a charge transporting material, and 100 parts of a bisphenol A type polycarbonate resin together with a predetermined amount of dichloromethane. For 2 hours to prepare a coating solution 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, dried at 100 ° C. for 1 hour, and
A single-layer type photosensitive layer having a thickness of 5 to 30 μm was formed to obtain a positively charged single-layer type electrophotographic photosensitive member. The charge generation material used was
In Tables 1 and 2, the above specific examples (B1) to (B1)
0), and the charge transporting material used was the same as the specific examples (A1) to (3) described above with respect to Examples.
Regarding the compound number of (A17) and the comparative example, the following formula (D)
The results are shown using the compound numbers of 1) to (D11). The following tests were performed on the electrophotographic photosensitive members of each of the above Examples and Comparative Examples, and the characteristics were evaluated. Electric characteristics The flow-in current value was adjusted by an electrostatic copying test apparatus (Gentec Cynthia 30M manufactured by Gentech) so that the surface of the sheet-like electrophotographic photosensitive member prepared in each of the examples and comparative examples was brought to around ± 800 V. After measuring the initial surface potential (V) at the time of charging, the most necessary 55
The half-exposure amount was measured using 0 nm light. That is,
550n taken out of the xenon lamp using a spectroscope
m light with an intensity of 0.2 mW / cm ² and an exposure time of 1 second to determine a half-reduced exposure amount (μJ / cm ² ). Further, the surface potential at the point when 0.5 seconds had elapsed immediately after the exposure was determined as the post-exposure potential (V). The electrophotographic photoreceptor obtained in each of the above Examples and Comparative Examples was repeated ,
After each was pasted on an aluminum cylinder using an adhesive tape, it was mounted on an electrostatic copying machine DC-1670M (manufactured by Mita Kogyo Co., Ltd.). Next, copying was repeated 10,000 times, and then the surface potential (V) and half-exposure amount (μ
J / cm ² ) and the post-exposure potential (V) were measured. The results are shown in Tables 1 and 2.

[Table 1]

[Table 2] As is clear from Tables 1 and 2, the electrophotographic photoreceptors of the present invention represented by Examples 1 to 12 have excellent post-exposure potentials, half-exposure amounts, and repetition characteristics. It can be seen that high performance is exhibited as a characteristic. In contrast, the electrophotographic photosensitive members of Comparative Examples 1 to 12 had higher potentials after exposure and had lower sensitivity. For this reason, fogging occurred from the beginning of copying, and even if the exposure lamp, which is standardly mounted in the electrostatic copying machine, was set to the maximum output, the potential corresponding to a white background was high and fogging occurred. Further, as is clear from Table 2, the electrophotographic photosensitive members of Comparative Examples 1, 4, 6, 7, 8, and 12 had extremely low 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, the compound represented by the general formula (2) is selected as the charge transporting material from the azo pigment represented by the general formula (1) as the charge generating material. Thus, an organic photoreceptor having excellent electrophotographic properties could be provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-53065 (JP, A) JP-A-3-96961 (JP, A) JP-A-1-283567 (JP, A) JP-A-1-283567 263657 (JP, A) JP-A 1-22057 (JP, A) JP-A-3-278063 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/06 351 G03G 5/06 312 G03G 5/06 313

Claims (1)

(57) [Claims] 1. A charge generating material having the following general formula (1) on a conductive substrate: (Wherein, A represents the same or different coupler residue, R1 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. And n represents 0 or 1.) and a charge transporting material represented by the following general formula (2): (Wherein R2, R3, R4 and R5 are the same or different and represent an alkyl group, an aryl group, or an aralkyl group;
Ar1 and Ar2 are the same or different and represent an arylene group. The alkyl group, aryl group, aralkyl group, and arylene group may have a substituent. An electrophotographic photoreceptor provided with a photosensitive layer containing the compound represented by the formula (1).