JPH0784387A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To select specific charge transport material so as to satisfy electrophotographic characteristic such as sensitivity, potential holding ability, potential stability and residual potential with high performance in an electrophotographic photoreceptor using a specific bisazo pigment. CONSTITUTION:A photosensitive layer containing a bisazo pigment, expressed by a formula I, as charge generating material and a compound, expressed by a formula II, as charge transport material is provided on a conductive base body. In the formula I, A represents a coupler residual group identically or differently, R represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group (the alkyl group, aryl group and heterocyclic group are allowed to have substituents), and (n) represents 0 or 1. In the formula II, R1-R4 represent an alkyl group or an aryl group.

Description

Detailed Description of the Invention

[0001]

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.

[0002]

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 the electrophotographic photosensitive member used in the above electrophotographic method, one using a specific bisazo pigment is known. (See JP-A 1-2202757).

[0004]

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. .

Japanese Patent Laid-Open No. 1-220757 discloses that a photosensitive member stable to heat and light can be obtained by using the general formula (1) and various carrier-moving substances. There is. 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. Compared with an oxadiazole type azo pigment having a coupler (Japanese Patent Application Laid-Open No. 59-229564), etc., it is more susceptible to oxidative deterioration due to ozone, nitrogen oxide NOx, light, etc. generated in the copying machine, and the photoconductor characteristics. There is a drawback that it is easy to cause a decrease in It is presumed that the oxidative deterioration of the bisazo 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 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 can be obtained without impairing the excellent characteristics of the bisazo pigment (1). I can't do that, and I'm still not satisfied enough. 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.

[0008]

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:

[0009]

[Chemical 3]

(In the formula, A is the same or different and represents a coupler residue, R is a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. The alkyl group, the aryl group, and the heterocyclic group are Which may have a substituent, n represents 0 or 1, and a bisazo pigment represented by the following general formula (2) as a charge transport material:

[0011]

[Chemical 4]

It was found that a photosensitive layer containing a compound represented by the formula (wherein R 1, R 2, R 3 and R 4 represent an alkyl group or an aryl group) may be provided, and the present invention is completed. Came to. 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.

That is, even if the output of the exposure lamp that is standardly installed in the copying machine is not increased, problems such as fog do not occur, which leads to a longer life of the exposure lamp and a reduction in power consumption. It is supposed to be.

[0014]

Preferred Embodiments Charge Generating Material In the bisazo pigment represented by the general formula (1), examples of the alkyl group corresponding to the group R in the formula include a methyl group, an ethyl group, a propyl group, an isopropyl group, 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.

Examples of the substituent group substituting for the above group include a halogen atom, an amino group, a hydroxyl group, an optionally esterified carboxyl group, a cyano group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group, an alkenyl group having 2 to 6 carbon atoms, which may have an aryl group, and the like. Examples of the coupler residue represented by A include groups represented by general formulas (a) to (g).

[0016]

[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, 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,
It may have a substituent such as a carbonyl group or a carboxyl group.

R ³¹ represents an atomic group necessary for forming an aromatic ring, a polycyclic hydrocarbon or a heterocycle by condensing with R ³⁰ and the benzene ring having a hydroxyl group, and these rings are as described above. You may have the same substituent. 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 above general formula (e)
The following formula (h) in (f)

[0020]

[Chemical 6]

It represents an atomic group necessary for forming 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,
It represents an amino group, a carbamoyl group, a sulfamoyl group, an allofanoyl group, 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 methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t
A butyl group, a pentyl group, a hexyl group, etc., having 1 to 1 carbon atoms
And 6 lower alkyl groups.

As the aryl group, for example, a phenyl group,
Examples thereof include 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

The aromatic ring formed by the condensation of R ³¹ with R ³⁰ and a benzene ring having a hydroxyl group is
Examples thereof 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 and a dibenzofuran ring. Further, in R ³¹ , the atomic group necessary for condensing with R ³⁰ and a benzene ring having a hydroxyl group to form a heterocycle is, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a 1H-indolyl group, a benzo Oxazolyl group, benzothiazolyl group, 1H-indadoryl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonilyl group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group , Xanthenyl group, acridinyl group, phenanthridinyl group, phenazinyl group, phenoxazinyl group, thianthrenyl group and the like.

Examples of the aromatic heterocyclic group formed by the condensation of 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 and a thiazolyl group. , Isothiazolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group and 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).

In R ³³ and 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.

In R ³⁵ , the atomic group necessary for forming a heterocycle with the moiety represented by the formula (h) is, for example, phenylene group, naphthylene group, phenanthrylene group, ethylene group, propylene group or butylene. Groups and the like. 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.

Examples of the carboxyl group ester in R ³⁶ include methyl ester, ethyl ester, propyl ester and butyl ester. Specific examples of the coupler residue A represented by the above general formulas (a) to (g) include the following groups.

[0030]

[Chemical 7]

[0031]

[Chemical 8]

[0032]

[Chemical 9]

[0033]

[Chemical 10]

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

[0035]

[Chemical 11]

[0036]

[Chemical 12]

[0037]

[Chemical 13]

As the charge generating material, in addition to the pigment represented by the general formula (1), the charge generating material is used 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. Therefore, other conventionally known charge generating materials can be used in combination. 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), R 1 in the formula
Examples of the alkyl group and aryl group corresponding to R4 include the same groups as those represented by the general formula (1).

Specific examples of the compound represented by the general formula (2) include compounds 1 to 15 as shown in Table 1 below. In the table, Me is a methyl group, Et is an ethyl group, and Ph is a phenyl group.

[0040]

[Table 1]

The compound represented by the general formula (2) can be synthesized by various methods. 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.

Examples of the electron-withdrawing compound include 2,
^{6-dimethyl-2,, 6,} - di tert- dibutyl phenoxide diphenoquinone derivatives non like, malononitrile, thiopyran compounds, tetracyanoethylene, 2,
4,8-trinitrothioxanthone, 3,4,5,7-
Tetranitro-9-fluorenone, dinitrobenzene,
Examples include dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride.

As the electron donating compound, 2,5
-Oxadiazole compounds such as di (4-methylaminophenyl) and 1,3,4-oxadiazole, 9- (4
-Styryl compounds such as diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indole Compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds,
Examples thereof include nitrogen-containing cyclic compounds such as imidazole compounds, pyrazole compounds, and triazole compounds, and condensed polycyclic compounds.

These charge transport materials may be used alone or in combination of two or more. When a charge transporting material having film-forming property such as polyvinylcarbazole is used,
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.

In order to improve the sensitivity of the charge generating layer, known sensitizers such as terphenyl, halonaphthoquinones and acenaphthylene may be used in combination with the charge generating 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, as long as the substrate itself has conductivity or the surface of the substrate has conductivity. 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, a compound represented by the general formula (1), which is a charge generating material, and a compound represented by the general formula (2), which is a charge transport material, A photosensitive layer containing a binder resin and the like may be formed on the conductive substrate by means such as coating. 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. Alternatively, conversely to the above, 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, but with respect to 100 parts of binder resin (weight part, the same applies hereinafter). , Charge generating material 5 to 1000 parts, especially 30
It is preferably used at a ratio of about 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 hinder the transport of charges and a range that does not crystallize, but they are generated in the charge generation layer by light irradiation. Binder resin 10 so that the accumulated electric charge can be easily transported.
10 parts to 500 parts, especially 25 parts of the charge transport material per 0 part.
It is preferably used in a proportion of about 200 parts.

The thickness of the laminated photosensitive layer is preferably 0.01 to 5 μm, particularly 0.1 to 3 μm, and 2 to 100 μm for the charge transport layer.
m, particularly preferably about 5 to 50 μm.
In a single-layer type photoreceptor, the charge generation material is 0.1 to 50 parts, particularly 0.5 to 30 parts, relative to 100 parts of the binder resin,
Suitably the charge transport material is 20 to 200 parts, especially 30 to 150 parts. The thickness of the single-layer type photosensitive layer is 5
The thickness is preferably about 100 to 100 μm, particularly about 10 to 50 μm.

In the case of a single-layer type photoreceptor, it is between a conductive substrate and a photosensitive layer, and in the case of a laminated type photoreceptor, it is between a conductive substrate and a charge generation layer, and a conductive substrate. A barrier layer may be formed between the charge transport layer and the charge transport layer or between the charge generation layer and the charge transport layer to the extent that the characteristics of the photoreceptor are not impaired. It may be formed. 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 solution, 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, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether and tetrahydrofuran. Examples include ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport material or the charge generating material and the smoothness of the surface of the photosensitive layer, 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. Glass beads (2 mm diameter) were used in Examples 1 to 12 and Comparative Examples 1 to 12 (multilayer type photoconductor), 0.7 parts by weight of the charge generating material, 1 part by weight of polyvinyl butyral resin, and a predetermined amount of cyclohexanone. Disperse with a paint shaker for 2 hours. The obtained dispersion liquid was applied onto the surface of an aluminum base tube as a conductive substrate by a dip coating method and dried at 120 ° C. for 1 hour to form a charge generation layer having a film thickness of 0.5 μm. The charge generation materials used are shown in Table 2 by using the compound numbers of the above-mentioned specific examples (B1) to (B10) and the compound numbers of the following formula (P1).

On this charge generation layer, 1 part by weight of a charge transport material and bisphenol A type polycarbonate resin 10 were used.
0 parts by weight and a solution of a predetermined amount dissolved in dichloromethane were applied by a dip coating method and dried at 100 ° C. for 1 hour,
A charge transport layer having a film thickness of 25 μm was formed to obtain a negative charging type laminated electrophotographic photosensitive member. The charge transport materials used are shown in Table 2 by using the compound numbers of the above-mentioned specific examples 1 to 15 and the compound numbers of the following formulas (K1) to (K11).

[0054]

[Chemical 14]

[0055]

[Chemical 15]

[0056]

[Chemical 16]

[0057]

[Chemical 17]

Examples 13-24 and Comparative Examples 13-24
(Single layer type photoreceptor) 4 parts by weight of charge generating material, 75 parts by weight of charge transporting material,
100 parts of bisphenol A-type polycarbonate resin was dispersed with a predetermined amount of dichloromethane for 2 hours using a paint shaker to prepare a coating solution for a single-layer type photosensitive layer. Then, this coating solution is applied to the surface of an aluminum tube as a conductive substrate by a dip coating method and dried at 80 ° C. for 120 minutes to form a single-layer type photosensitive layer having a film thickness of 25 μm, and positively charged. A single-layer type electrophotographic photoreceptor of the type was obtained.

The charge generating material used is shown in Table 3 below.
Conversion of the specific examples (B1) to (B10) and (P1) described above
Charge transport materials used by compound number
Is the compound number of the above specific examples 1 to 15 and the above formula
The compound numbers (K1) to (K11) are used. Up
The following test was performed on the electrophotographic photoconductors of Examples and Comparative Examples.
A test was conducted and its characteristics were evaluated.Electrical characteristics Electrostatic copying tester (Gentech Co., Ltd., Shinshi
A) the flow-in current value by
± 800V on the surface of the electrophotographic photosensitive member created in the comparative example
The initial surface potential (V) at the time of near charging was measured.
After that, using the light of 550nm which is most necessary for the PPC photoconductor
Then, the half-dose exposure was measured. That is, a xenon lamp
The intensity of 550 nm light extracted using a spectroscope is 10
μW / cm ², Exposure time 1 second, half exposure
(ΜJ / cm²) Was asked. In addition, 1.0 immediately after exposure
The surface potential at the time when a second has elapsed is obtained as the post-exposure potential (V).
I haveRepeatability The electrophotographic photosensitive member obtained in each of the examples and comparative examples,
For electrostatic copier DC-1670M (manufactured by Mita Industry Co., Ltd.)
I put it on.

After copying was repeated 20,000 times, the surface potential (V), the half-exposure amount (μJ / cm ² ), and the post-exposure potential (V) were measured in the same manner as above. The above results are shown in Tables 2, 3 and 4.

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

As is clear from Tables 2, 3 and 4, the electrophotographic photosensitive members of the present invention represented by Examples 1 to 24 are:
It can be seen that it has excellent post-exposure potential, half-exposure amount and repetitive characteristics, and exhibits high performance as electrophotographic characteristics. On the other hand, the electrophotographic photoreceptors of Comparative Examples 1 to 24 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 4, the electrophotographic photosensitive members of Comparative Examples 3, 5, 12, 17, 21, and 24 are
The surface potential was extremely lowered by repeated use. Therefore, in the image confirmation after repeated copying, the contrast potential was reduced and the image density was also reduced.

[0066]

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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Iwasaki 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture Mita Industry Co., Ltd. (72) Hirosuke Sakai 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture No. 28 Mita Industry Co., Ltd. (72) Inventor Tomoki Tanaka 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Mita Industry Co., Ltd.

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 is a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. The alkyl group, the aryl group, and the heterocyclic group are substituents. Bisazo pigment represented by the following general formula (2) as a charge transporting material: (In the formula, R1, R2, R3, and R4 represent an alkyl group or an aryl group.) An electrophotographic photosensitive member is provided with a photosensitive layer containing a compound represented by the formula.