JPH01197759A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent degradation of electrostatic charge potential and to improve durability even in long-term repetitive use by using the compd. expressed by the prescribed formula as a charge generating material and incorporating a hydroquinone compd. into a photosensitive layer. CONSTITUTION:This photosensitive body has the photosensitive layer contg. the charge generating material and charge transfer material on a conductive base. The compd. expressed by the formula is used as the charge generating material and the hydroquinone compd. is incorporated into the photosensitive layer. In the formula, A, A' denote a residual coupler group having a phenolic OH group.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to an electrophotographic photoreceptor.

In particular, the present invention relates to an electrophotographic photoreceptor that has excellent charging stability even during repeated use over a long period of time.

[Prior art]

Inorganic materials such as selenium, cadmium sulfide, ram, and zinc oxide have been conventionally known as photoconductive materials for electrophotographic photoreceptors. However, these inorganic substances do not necessarily meet the characteristics such as photosensitivity, thermal stability, and durability required for electrophotographic photoreceptors, as well as the manufacturing conditions.For example, selenium has the characteristic of being easily crystallized by heat, dirt, etc. It is easy to deteriorate, and the manufacturing cost, impact resistance,
It has drawbacks such as toxicity and the need for careful handling'.

Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Also zinc oxide.

It has the disadvantage of being inferior in moisture resistance and durability.

For electrophotographic photoreceptors using these inorganic photoconductive materials,
Photoreceptors using organic photoconductive substances are being actively researched and developed because of their light weight, ease of film formation, manufacturing cost, and wide variation as organic compounds. For example, in the early days, there was a photoreceptor containing polyvinylcarbazole and 2,4,7-dolinitro-9-fluorenone described in Japanese Patent Publication No. 10496/1982;
A photoreceptor in which polyvinyl carbazole is sensitized with a pyrylium salt dye, as described in Japanese Patent No. 25658, or a photoreceptor having a eutectic complex as a main component has been proposed. However, these photoreceptors do not have sufficient sensitivity and durability.

Therefore, in recent years, a functionally separated type photoreceptor in which a charge generation layer and a charge transport layer are separated has been proposed, and
A photoreceptor that combines chlordiane blue and a hydrazone compound described in the issue, ? ! ! The biological substances to be shipped are described as bisazo compounds in JP-A-53-133445, JP-A-54-21728, and JP-A-54-228.
34, as a charge transport material, JP-A-58-1
98043 and those described in JP-A-58-199352 are known.

However, these function-separated photoreceptors are still unsatisfactory, especially in terms of durability.In recent years, as demands for durability have increased more and more, ensuring charging stability has become an issue that cannot be ignored. . That is, if the charging property decreases, it causes a decrease in the image density of the copy in a copying machine, and in the case of a laser printer using a reversal development method, it causes a decrease in image quality such as background staining. to solve these problems.

It has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a crystal resistive material with high barrier properties is used for the intermediate layer in order to stabilize chargeability, although the chargeability is improved, there are drawbacks such as a decrease in photosensitivity and an increase in residual potential. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, the charging stability will be insufficient.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that can prevent a decrease in charging potential even during repeated use over a long period of time and has greatly improved durability.

〔composition〕

According to the present invention, in an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating substance and a charge transporting substance is provided on a conductive support, a compound represented by the following general formula (1) is used as a charge generating substance. There is also provided an electrophotographic photoreceptor characterized in that the photosensitive layer contains a hydroquinone compound.

(In the formula, A and A' represent coupler residues having a phenolic OH group.) The electrophotographic photoreceptor of the present invention uses a disazo pigment represented by the general formula (1) as a charge generating substance, and a photosensitive material. Since the layer contains a hydroquinone compound, it is possible to reliably suppress the deterioration of the chargeability of the photoreceptor due to repeated use, thereby providing stable and clear copied images over a long period of time.

In the present invention, as a charge generating substance, the general formula (I
) is used, but it is preferable to use one in which the coupler residue (^) is the following group.

[Example of coupler residue]

2・x-' \2' 5・z-' Man,.

(In the formula, X is a naphthalene ring fused with a benzene ring,
Represents a residue necessary to form a polycyclic aromatic ring or heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, and diphenylene sulfide ring, and R1□ and ntz are hydrogen atoms, substituted, and unsubstituted. Represents a group selected from substituted alkyl, aralkyl, aryl and heterocyclic groups, Lx and 2 may form a cyclic amino group together with the nitrogen atom to which they are bonded, R11, R1
4 is a group selected from substituted or unsubstituted alkyl groups, aralkyl groups, and aryl groups, and Y' is a divalent group of aromatic hydrocarbons or a divalent group of a petero ring containing a nitrogen atom in the ring.

R15, R1, R1□, and R1 represent a group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, an aryl group, and a heterocyclic group, and R1? * Rlm is 5
fi or a 6-membered ring, in which case this 5
The membered or six-membered ring may have a fused aromatic ring.

2 is a naphthalene ring fused with a benzene ring.

5Arl indicates a residue necessary to form a polycyclic aromatic ring or a petro ring selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring, and 5Arl is a benzene ring, naphthalene ring, etc. Aromatic rings and their substituents @
R111 represents hydrogen, a lower alkyl group, a carboxyl group, or an ester thereof.) Specific examples of the disazo pigment represented by the above-mentioned -formation (1) used in the present invention are shown below.

Hydroquinone compounds that can be used in the present invention include hydroquinone, methylhydroquinone, 2,
3-dimethylhydroquinone, 2,5-dimethylhydroquinone, 2,6-dimethylhydroquinone, trimethylhydroquinone, tetramethylhydroquinone, t-
Butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,5-di-amylhydroquinone, chlorohydroquinone, 2,5-di-t-octylhydroquinone, 2-t-butyl-5-methylhydroquinone, l
, 4-diolnaphthalene, 9,10-diolanthracene, and other hydroquinone derivatives, but 2.5-di-t-butylhydroquinone is particularly preferred from the viewpoint of effectiveness.

Furthermore, in the present invention, two or more of the above hydroquinone and type compounds can be used in combination.

Further, in the present invention, a charge transport substance is used together with a charge generation substance, and the charge transport substance includes a hole transport substance and an electron transport substance. Examples of the hole transport substance include compounds represented by the following general formulas (1) to (12).

In the KlC formula, R1 represents a methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R2 represents a methyl group, ethyl group, benzyl group, or phenyl group, and R
1 represents hydrogen, chlorine, bromine, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a dialkylamino group, or a nitro group. [In the formula, Ar represents naphthalenes, anthracenes, styryl groups, and substituted products thereof, pyridines, furans, and thiophenes, and R represents an alkyl group or a benzyl group. ] [In the formula, R1 is an alkyl group, a benzyl group, a phenyl group,
Represents a naphthyl group, R2 represents hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group, a dialkylamino group, or a diarylamino group, and n represents an integer of 1 to 4. When n is 2 or more, R2 may be the same or different, and R1 represents hydrogen or a methoxy group. ] 1 [In the formula, R1 represents an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group, or a heterocyclic group, R,,
R, each of which may be the same or different, represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloroalkyl group, a substituted or unsubstituted aralkyl group,
Further, R2 and R3 may be bonded to each other to form a nitrogen-containing heterocycle. R4 may be the same or different and represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen. [In the formula, R represents hydrogen or a halogen atom, and Ar is a substituted or unsubstituted phenyl group or naphthyl group.

Represents an anthryl group or a carbazolyl group. [In the formula, R1 represents hydrogen, halogen, cyano group, alkoxy group having 1 to 4 carbon atoms, or alkyl group having 1 to 4 carbon atoms, Ar is R2 represents an alkyl group having 1 to 4 carbon atoms, and R3 is hydrogen, halogen, alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms
represents an alkoxy group or dialkylamino group, n
is 1 or 2, and when n is 2, R3 may be the same or different, R4 and R1 are hydrogen, and have 1 to 4 carbon atoms.
represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted benzyl group. [In the formula, R is a carbazolyl group, a pyridine group, a thienyl group, an indolyl group, a furyl group, or a substituted or unsubstituted phenyl group, a styryl group, a naphthyl group, or an anthryl group, and these substituents are dialkylamino group, alkyl group, alkoxy group, carboxy group or ester thereof, halogen atom.

Represents a group selected from the group consisting of a cyano group, an aralkylamino group, an N-alkyl-N-aralkyl amino group, an amino group, a nitro group, and an acetylamino group. [In the formula, R1 represents a lower alkyl group or a benzyl group, and R2 is a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, an amino group, or an amino group substituted with a lower alkyl group or a benzyl group. , and n represents an integer of 1 or 2. [In the formula, R1 represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, R3 and R3 represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, and R4 represents hydrogen represents an atom or a substituted or unsubstituted phenyl group, and
Ar represents a phenyl group or a naphthyl group,] [wherein n is an integer of 0 or l, R1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group,
R2 and R1 represent hydrogen, a halogen atom, an alkyl group,
A represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group, where R4 is a hydrogen atom,
Alkyl group, alkoxy group, halogen atom alkyl group,
represents a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, R3 and RG may form a ring), m is an integer of 0, 1.2 or 3, and I is When 2 or more, R2 may be the same or different;
] [In the formula, R1, R, and R1 represent hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group, or a halogen atom, and n represents 0 or 1.] [In the formula, R1 represents a hydrogen atom, an alkyl R2 and R1 may be the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom. ] Compounds represented by General Taisei 1) include, for example, 9-ethylcarbazol-3-aldehyde, l-methyl-1-
Phenylhydrazone, 9-ethylcarbazole-3-aldehyde l-benzyl-1-phenylhydrazone, 9-
and ethylcarbazole-3-aldehyde 1,1-diphenylhydrazone.

Examples of the compound represented by the general formula (2) include 4-diethylaminostyrene-β-aldehyde l-methyl-1
-Phenylhydrazone, 4-methoxynaphthalene-1-
Examples include aldehyde 1-benzyl-1-phenylhydrazone.

Examples of the compound represented by the general formula (3) include 4-methoxybenzaldehyde 1-methyl 11-phenylhydrazone, 2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone, and 4-diethylaminobenzaldehyde 1,1-diphenyl. hydrazone, 4-methoxybenzaldehyde 1-benzyl-1-(4-methoxy)phenylhydrazone, 4-diphenylaminobenzaldehyde 1-benzyl-1-phenylhydrazone,
Examples include 4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone.

The compound represented by general formula (4) includes, for example, 1.1
-bis(4-dibenzylami, nophenyl)propane,
Tris(4-diethylaminophenyl)methane, 1. l
-bis(4-dibenzylaminophenyl)propane, 2
．． 2'dimethyl-4,4'-bis(diethylamino)-
Examples include triphenylmethane.

The compound represented by general formula (5) includes, for example, 9-(
Examples include 4-diethylaminostyryl)anthracene and 9-bromo-10-(4-diethylaminostyryl)anthracene.

The compound represented by general formula (6) includes, for example, 9-(
4-dimethylaminobenzylidene) fluorene, 3-(
Examples include 9-fluorenonedene)-9-ethylcarbazole.

The compound represented by general formula (7) includes, for example, 1.2
-bis(4-diethylaminostyryl)benzene, 1.
2-bis(2,4-dimethoxystyryl)benzene.

Examples of the compound represented by the general formula (8) include 3-styryl-9-ethylcarbazole and 3-(4-methoxystyryl)-9-ethylcarbazole.

Examples of the compound represented by the general formula (9) include 4-diphenylaminostilbene, 4-dibenzylaminostilbene, and 4-ditolyllaminostilbene.

1-(4-diphenylaminostyryl)naphthalene, 1
-(4-diethylaminostyryl)naphthylene, etc.

The compound represented by the general formula (10) includes, for example, 4'
-diphenylamino-α-phenylstilbene, 4'-
Examples include methylphenylamino-α-phenylstilbene.

The compound represented by the general formula (11) includes, for example, 1-
Phenyl-3-(4-diethylaminostyryl)-5-
(4-diethylaminophenyl)pyrazoline, ■-phenyl-3-(4-dimethylaminostyryl)-5-(4
-dimethylaminophenyl)pyrazoline, etc.
-The compound represented by general formula (12) includes N,
N'-diphenyl-N, N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'diphenyl-N.

Examples include N'-bis(chlorophenyl)-(1,1'-biphenyl]-4°4'-diamine and 3,3'-dimethylbenzidine.

Other hole transport substances include, for example, 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole, 2,5-bis(4-(4-diethylaminostyryl)phenyl)- 1,3,4-oxydiazole, 2-(9-ethylcarbazolyl-3-)-5-(4
oxadiazole compounds such as -diethylaminophenyl)-1,3,4-oxadiazole, 2-vinyl-4
There are low molecular weight compounds such as oxazole compounds such as -(2-chlorophenyl)-5-(4-diethylaminophenyl)oxazole and 2-(4-diethylaminophenyl)-4-phenyloxazole. Also, poly-N-
Vinyl carbazole.

High molecular compounds such as halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, pyrene formaldehyde resin, and ethylcarbazole formaldehyde resin can also be used.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4.7-dolinitro-9-fluorenone, 2,4,5. Tutetranitro-9-fluorenone,
2,4,5.7-titranitroxanthone, 2,4°8
-trinidrothioxanthone, 2,6.8-trinitro-4H-indeno(1,2-b)thiophen-4-one, 1,3.7-dolinitrodibenzothiophene-5,
Examples include 5-dioxide.

The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a monodisperse type or a functionally separated type by combining a charge generating substance and a charge transporting substance.

In the case of a dispersed layer structure, a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder is provided on a conductive substrate.

In the case of a functionally separated type, a charge generation layer containing a charge generation substance and a binder is formed on the substrate, and a charge transport layer containing a charge transport substance and a binder is formed on top of the charge generation layer. In this case, the charge generation layer and the charge transport layer may be laminated in reverse order.In addition, in the case of a functionally separated type, a charge transport substance may be contained in the charge generation layer, especially in the case of a positively charged structure. Sensitivity becomes better.

Additionally, an intermediate layer may be provided between the photosensitive layer and the substrate to improve adhesion and charge blocking properties, and a protective layer may be provided on the photosensitive layer to further improve mechanical durability such as abrasion resistance. may be provided. Binders used in forming the charge generation layer, charge transport layer and separate photosensitive layer include polycarbonate (bisphenol A type, bisphenol 2 type), polyester, methacrylic resin, acrylic resin,
Polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenolic resin, epoxy resin, polyurethane, vinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyarylate, polyacrylamide, polyamide, phenoxy resin, etc. are used. . These binders can be used alone or as a mixture of two or more.

When producing a photoreceptor using the layer structure and materials described above, there is a preferable range for the film thickness and the ratio of the materials.

In the case of a negatively charged type (substrate/charge-generating N/charge-transporting layer stack), the ratio of the charge-generating substance to the binder in the charge-generating layer is 20 to 500% by weight, and the film thickness is 0.1 to 5-5%. i
In the charge transport layer, the ratio of the charge transport substance to the binder is preferably 20 to 200 weight, and the film thickness is preferably 5 to 50 weight.

Positive charging type (layered structure of substrate/charge transport layer/ffi charge generation layer)
In this case, in the charge transport layer, the ratio of the charge transport substance to the binder is 20 to 200% by weight, and the film thickness is 5 to 50% by weight.
It is preferable to set it to μm. In the charge generation layer, the charge generation substance is preferably contained in an amount of 10 to 100% by weight based on the binder. Furthermore, it is preferable to include a charge transporting substance in the charge generation layer, which has the effect of suppressing residual potential and improving sensitivity. In this case, the charge transport material is preferably contained in an amount of 20 to 200 parts by weight based on the binder.

Further, the amount of hydroquinone and/or its derivative of the present invention to be added to the photosensitive layer is 0.01 to 5.0% relative to the charge transport material when added to the charge transport layer in the case of a functionally separated type.
Preferably it is 0% by weight. When added to the charge generation layer, it is preferably added in an amount of 0.1 to 20.0% by weight 2 based on the charge generation material. In the case of a dispersed type, it is preferably added in an amount of 0.01 to 5.0% by weight based on the charge transport material.

The hydroquinone derivative may be added to any layer, but this is because the hydroquinone derivative is diffused into other layers by the coating dispersion medium or solvent during coating of the photosensitive layer.

Generally, the intermediate layer provided as needed is mainly composed of resin, but considering that the photosensitive layer is coated on top of it with a solvent, these resins have a high solvent resistance to general organic solvents. It is desirable that the resin has high properties. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate; alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon; and three-dimensional resins such as polyurethane, melamine resin, phenolic resin, and epoxy resin. Examples include curable resins that form a network structure.

In addition, fine powder pigments of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the intermediate layer to prevent moire and reduce residual potential.

Solvents or dispersion media used in forming the charge generation layer and the charge transport layer include N,N'-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, Dichloromethane, monochlorobenzene, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate.

Dimethyl sulfoxide and the like can be mentioned.

The photosensitive layer can be formed by immersing the substrate in a coating solution for the charge generation layer or charge transport layer, or by spraying the coating solution onto the substrate.

Substrates used in the electrophotographic photoreceptor of the present invention include metal drums and sheets made of aluminum, brass, stainless steel, nickel, etc., materials such as polyethylene terephthalate, polypropylene, nylon, paper, etc., on which metals such as aluminum and nickel are vapor-deposited. , or titanium oxide,
Examples include sheet-like or cylindrical substrates such as plastics and paper that are coated with a conductive substance such as tin oxide or carbon black together with a suitable binder to conductivity treatment.

〔effect〕

Since the electrophotographic photoreceptor of the present invention has the above-mentioned structure, the photoreceptor characteristics such as chargeability do not deteriorate even after repeated use over a long period of time, and therefore its practical value is extremely high.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Alcohol-soluble nylon resin (CM-8000, nylon 6/66/610/12 copolymer, manufactured by Toshi Co., Ltd.) 1 was placed on an aluminum drum with a diameter of 80 mm and a length of 340+a+*.
A coating solution consisting of 0 parts by weight and 190 parts by weight of ethyl alcohol was applied by dip coating, and dried at 120°C for 5 minutes to a thickness of 0.2
- An intermediate layer was provided. Next, polyvinyl butyral resin (
4 parts by weight of XYIIL (manufactured by Union Carbide Co.) was dissolved in 150 parts by weight of cyclohexanone, and exemplified compound No.

10 parts by weight of the dizazo pigment (61) was added and dispersed in a ball mill for 48 hours, followed by 210 parts by weight of cyclohexanone and 0.0 parts by weight of 2,5-di-tart-butylhydroquinone.
2 parts by weight were added and dispersion was carried out for 3 hours. This was taken out into a container and diluted with cyclohexanone while stirring so that the solid content was 1.0% by weight. The charge generation layer coating solution thus obtained was dip coated onto the intermediate layer and dried at 120°C for 5 minutes to form a charge generation layer with a thickness of 0.2. ), 10 parts by weight of polycarbonate resin (Panlite = 1300; manufactured by Teijin Kasei Co., Ltd.), 0.002 parts by weight of silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.), and 85 parts by weight of methylene chloride. A charge transport layer coating solution was prepared by dissolving it in This was applied by dip coating onto the charge generation layer and dried at 120° C. for 15 minutes to form a charge transport layer with a thickness of 20 pm. In this way, the photoreceptor of the present invention was produced.

Examples 2 to 4 Additive 2 to the charge generation layer used in Example 1
A photoreceptor of the present invention was prepared in the same manner as in Example 1, except that the compounds shown in the table below were used in place of 5-di-tart-butylhydroquinone.

Examples 5 to 6 Examples of azo pigments N as disazo pigments in the charge generation layer
Photoreceptors of the present invention were prepared in the same manner as in Example 1 except that o(28) and (35) were used.

Comparative Examples 1 to 3 Three types of photoreceptors for comparison were prepared in the same manner as in Example 1, except that the additives added to the charge generation layer in Example 1 were replaced with those shown in the table below.

Example 7 Example 1 except that 0.04 parts by weight of 2,5-di-tart-butylhydroquinone was added to the charge transport layer of Example 1, and 2,5-di-tart-butylhydroquinone was further removed from the charge generation layer. A photoreceptor was prepared in the same manner as in Example 1.

FT-55, which is a modified photoreceptor obtained as described above.
10 (manufactured by Ricoh) for evaluation. The modifications included making each process capable of evaluating negative i-type photoreceptors, and also removing the developing device and installing a surface electrometer therein for potential evaluation.

The surface potential of the modified FT-5510 was measured at the initial stage and after 20,000 copies were processed. The results are shown in Table-1.

Table 1 Example 8 8 parts by weight of the charge transport substance used in Example 1, polycarbonate resin (Panlite-1300: Teijin Kasei Co., Ltd.
J) 10 parts by weight and 0.002 parts by weight of silicone oil (KF-50: Shin-Etsu Chemical Co., Ltd.) were dissolved in 85 parts by weight of methylene chloride.

A charge transport layer coating solution was prepared. This is φ80, length 34
Dip coating was carried out on a 0 mm aluminum drum, and 12
It was dried at 0° C. for 15 minutes to form a charge transport layer with a thickness of 20/4I. Next, polycarbonate resin (Panlite L-
1250, manufactured by Teijin Kasei Co., Ltd.) was dissolved in 150 parts by weight of cyclohexanone, and exemplified compound no.

1.2 parts by weight of the disazo pigment (13) was added and dispersed in a ball mill for 48 hours, followed by 210 parts by weight of cyclohexanone, 3 parts by weight of the charge transport substance represented by the structural formula (a), and 2,5-diazole. tert-butylhydroquinone 0
．． 015 parts by weight was added and dispersion was carried out for 3 hours. This was taken out into a container and diluted with cyclohexanone while stirring so that the solid content was 1.0% by weight. The thus obtained charge generation layer coating liquid was spray coated onto the charge transport layer and dried at 120° C. for 10 minutes to form a charge generation layer with a thickness of 3 μm, thereby producing an electrophotographic photoreceptor of the present invention.

Comparative Example 4 A photoreceptor was prepared in the same manner as in Example 8 except that 2,5-di-tert-butylhydroquinone was removed from the charge generation layer of Example 8.

Next, the photoconductor obtained in Example 8 and Comparative Example 4 was modified to remove the developing section and to be equipped with a surface electrometer.
Attached to T5510 (made by Ricoh), initial and 20000
The surface potential after the sheet copying process was measured and evaluated. The results are shown in Table 2.6 Table 2 Patent applicant Rico Co., Ltd. - Procedural amendment 1, case display address 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 151 Address 158-10 Daiichi Nishiwaki Building 113, Yoyogi, Shibuya-ku, Tokyo Name (7450) Patent attorney Toshiaki Ikeura Telephone (j7o) No. 2533 No. 7, Subject of amendment Method () Column 8 of detailed explanation of the invention in the specification, Contents of amendment The following amendments will be made in the specification of the application.

(1) r coupler residue (A) on page 5, line 13,
Correct the r coupler residue (A, A') to J.

(2) Insert the following chemical formula between "(in the formula, X is...") on line 14 from the bottom of page 7.

Ar, J (3) Shows [ on page 8, line 14. Indicates the month. A
r.

represents an aromatic ring such as a benzene ring or a naphthalene ring, and a substituted product thereof; R2° represents a lower alkyl group, a carboxyl group, or a substituted product thereof. I'll correct it to the month.

(4) "Separate type" in the second line from the bottom of page 34 will be corrected to "distributed type."

(5) On page 36, line 10, change "It is preferable to contain." to "It is preferable to contain it, and the film thickness is 0.
It is preferable to set it as 5-10 micrometers. ” will be corrected.

(6) Page 40, line 6, “Light=1300J, [
I will correct it to 11300J for the light.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which a photosensitive layer containing a charge-generating substance and a charge-transporting substance is provided on a conductive support, a compound represented by the following general formula (I) is used as the charge-generating substance, and An electrophotographic photoreceptor characterized in that a photosensitive layer contains a hydroquinone compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, A and A' represent coupler residues having a phenolic OH group.)