JPH01197758A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To surely suppress the degradation in the electrostatic chargeability of a photosensitive body by repetitive use and to obtain stable and sharp copied images over a long period of time by using the compd. expressed by the prescribed formula as a charge generating material. CONSTITUTION:This photosensitive body has a 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 a hydroquinone compd. is incorporated into the photosensitive layer. In the formula, Ar1-Ar5 denote a substd. or unsubstd. residual carbon cyclic arm. group or residual heterocyclic atom. group; A and A' denote a residual coupler group having a phenolic OH group; R1-R6 denote a hydrogen atom, substd. or unsubstd. alkyl group or aralkyl group or electron-withdrawing group such as cyano group, halogen or nitro group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor that has excellent charging stability even when used repeatedly over a long period of time.

[Prior art]

Inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been conventionally known as photoconductive materials for electrophotographic photoreceptors. However, these inorganic materials do not necessarily satisfy the characteristics such as photosensitivity, thermal stability, and durability required for electrophotographic photoreceptors, as well as manufacturing conditions. For example, selenium has drawbacks such as being easily crystallized by heat, dirt, etc. and having properties deteriorate easily, and requiring care in handling such as manufacturing cost, impact resistance, and toxicity.

Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Zinc oxide also has the disadvantage of poor 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 variety of 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 comprising a combination of chlordiane blue and a hydrazone compound as described in JP-A-53-133445, JP-A-54-21728, and JP-A-54-22834 with a bisazo compound as the charge generating substance.
The charge transport material described in the publication is JP-A-571-19.
8043, JP-A-58-199352, etc. are known.

However, even these function-separated photoreceptors are not satisfactory, 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. In order to solve these problems,
It has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize the chargeability, although the chargeability is improved, there are disadvantages in that the photosensitivity decreases and the residual potential increases. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, 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, the charge-generating substance is represented by the following general formula (1) or general formula (II). There is provided an electrophotographic photoreceptor characterized in that the compound represented by the formula is used, and the photosensitive layer contains a hydroquinone compound.

R, RG (wherein, Ar, Ar2, Ar, Ar, or Ar,
is a substituted or unsubstituted carbocyclic aromatic residue or a heterocyclic aromatic residue, A and A' are coupler residues having a phenolic 011 group, R,, R2, R1, R4, R,
and R6 represents a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, or an electron-withdrawing group such as a cyano group, halogen, or nitro group.

The electrophotographic photoreceptor of the present invention uses a disazo pigment represented by the above general formula (1) or general formula (II) as a charge generating substance and contains a hydroquinone compound in the photosensitive layer, so that it can be used repeatedly. Since deterioration in the chargeability of the photoreceptor can be reliably suppressed, stable and clear copied images can be provided over a long period of time.

In the present invention, as a charge generating substance, the general formula (1
) or a disazo pigment represented by general formula (II), but it is preferable to use one in which the coupler residue (A or A') is the following group.

[Example of coupler residue]

2・x-' , -Y.

υ■ , -Y・, 1, z−'′・Z−' (wherein, 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 RLI and Lx are hydrogen atoms, substituted, and unsubstituted. II'L3 represents a group selected from alkyl, aralkyl, aryl and heterocyclic groups, and Rut and Rlm may form a cyclic amino group together with the nitrogen atom to which they are bonded.
．． R14 is a group selected from substituted or unsubstituted alkyl groups, aralkyl groups, and aryl groups, and Y is a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring.

Flts, FitRh7s L@ represents a group selected from a hydrogen atom, a W1-substituted, unsubstituted alkyl group, an aralkyl group, an aryl group, and a heterocyclic group, and fltv, R1
1l may form a 5- or 6-membered ring, and in this case, this 5- or 6-membered ring may have a fused aromatic ring.

2 is a naphthalene ring fused with a benzene ring.

Residues necessary to form a polycyclic aromatic ring or heterocycle selected from anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, benzonaphthofuran ring, and diphenylene sulfide ring are shown. ) General formula (1) or general formula (II) used in the present invention
) Specific examples of disazo pigments are shown below.

^ ^
^-N no-no ~no
- Nobeak
V3 Cl
C-ω ^ ^
^
To ^
good - no -no
-ノ
ν^ ^
^ Mae ■ Low Bay's Fung
enemy -ノ
-ノ -ノト
A lo 8u”
a
u'akinuma 〇 -to
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-7-butylhydroquinone, 2,5-di-amylhydroquinone, chlorohydroquinone, 2,5-di-t-octylhydroquinone, 2-t-butyl-5-methylhydroquinone,
Although hydroquinone derivatives such as 1,4-diolnaphthalene and 9,10-diolanthracene may be mentioned, it is particularly preferable to use 2゜5-di-t-butylhydroquinone in view of the expression of effects. The above hydroquinone compounds can also be used in combination of two or more.

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 formula C, R1 represents a methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R3 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; groups and their substituents or pyridines.

Represents furans, thiophenes, and R represents an alkyl group or a benzyl group.] [In the formula, R1 represents 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 alkyl 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; R3 represents hydrogen or a methoxy group; [wherein R1 has 1 to 1 carbon atoms]
11 alkyl group, substituted or unsubstituted phenyl group, or heterocyclic group, R, R3 may be the same or different, and hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloralkyl group , represents a substituted or unsubstituted aralkyl group, and R2 and R1 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,] [wherein R1 represents hydrogen, halogen, a cyano group, an alkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms, and R2 represents an alkyl group having 1 to 4 carbon atoms; 4 represents an alkyl group, and R3 is hydrogen.

represents a halogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a dialkylamino group, where n is 1 or 2, and when n is 2, R3 may be the same or different; R4 and R6 represent hydrogen, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group,] [wherein R is a carbazolyl group, a pyridine group, a thienyl group, an indolyl group, or a furyl group. group or substituted or unsubstituted phenyl group, styryl group,
A naphthyl group or an anthryl group, in which these substituents are a dialkylamino group, an alkyl group, an alkoxy group,
(R) represents a group selected from the group consisting of a carboxy group or an ester thereof, a halogen atom, 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 represents 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. where 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, R2 and R3 represent an alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, and R4 represents a hydrogen atom or It represents a substituted or unsubstituted phenyl group, and Ar represents a substituted or unsubstituted phenyl group or naphthyl group. [In the formula, n is an integer of 0 or 1, R1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group,
R,, R3 represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group or an alkoxy group, A represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group, where R9 is hydrogen atom, alkyl group, alkoxy group, halogen atom alkyl group, substituted or 5trt-substituted aralkyl group.

Represents a substituted or unsubstituted aryl group, R5 and R6
may form a ring), the garden is an integer of 0, 1.2 or 3, and when m is 2 or more, Rll may be the same or different.] [In the formula, R1, R2 and R3 represent hydrogen, a lower alkyl group, a lower alkoxy group, a dialkylamino group, or a halogen atom, and n represents 0 or 1.
R1 represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and Rt and R3 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 formula 1) include, for example, 9-nitylcarbazol-3-aldehyde, 1-methyl-1-
Phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1-benzyl-1-phenylhydrazone, 9-
Examples include nityl lupazol-3-aldehyde 1,1-diphenylhydrazone.

The compound represented by general formula (2) includes, for example, 4-
Diethylaminostyrene-β-aldehyde 1-methyl-
1-phenylhydrazone, 4-methoxynaphthalene-1
-Aldehyde 1-benzyl-1-phenylhydrazone and the like.

Examples of the compound represented by the general formula (3) include 4-methoxybenzaldehyde 1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone, and 4-diethylaminobenzaldehyde 1,1 -Diphenylhydrazone.

4-methoxybenzaldehyde 1-benzyl-1-(4
-methoxy)phenylhydrazone, 4-diphenylaminobenzaldehyde l-benzyl-1-phenylhydrazone, 4-dibenzylaminobenzaldehyde-1,1
-Diphenylhydrazone, etc.

The compound represented by general formula (4) includes, for example, 1.1
-bis(4-dibenzylaminophenyl)propane.

Tris(4-diethylaminophenyl)methane, 1.
1-bis(4-dibenzylaminophenyl)propane,
2.2'dimethyl-4,4'-bis(diethylamino)
- Triphenylmethane, etc.

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-fluorenylidene)-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.

The compound represented by the general formula (9) includes, for example, 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, 1- (4-
Examples include diphenylaminostyryl)naphthalene and 1-(4-diethylaminostyryl)naphthylene.

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, 1-phenyl-3-(4-dimethylaminostyryl)-5-(4
-dimethylaminophenyl)pyrazoline, etc.

- Compounds represented by the formula (12) include N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(
1,1'-biphenyl)-4,4'-diamine, N,
N'diphenyl-N.

Examples include N'-bis(chlorophenyl)-El, 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-diethyl7minophenyl)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 the electron transport substance include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5,7-tetranitro-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-5,5
- Dioxide, etc.

The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a dispersed type or a monofunctionally 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.

In addition, 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 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 A 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 (stacked charge generation layer/charge transport layer on a substrate), the ratio of the charge generation substance to the binder in the charge generation layer is 20 to 500% by weight, and the film thickness is 0.1 to 51JI.
A is preferable; in the charge transport layer, the ratio of the charge transport material to the binder is 20-200% by weight, and the film thickness is 5-20% by weight.
50. It is preferable that

In the case of a positively charged type (laminated base/charge transport layer/charge generation layer), the ratio of charge transport material to binder in the charge transport layer is 20 to 200% by weight, and the film thickness is 5 to 50p. is preferable. 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 transport substance in the charge generation layer, which has the effect of suppressing residual potential and improving sensitivity. It is preferable to contain it in parts by weight.

In addition, the amount of hydroquinone and l or its derivatives of the present invention to be added to the photosensitive layer is 0.00% relative to the charge transport material when added to the charge transport layer in the case of a functionally separated type. O1-5.
Preferably it is 0% by weight. When added to the charge generation layer, the amount is preferably 0.1 to 20.0% by weight based on the charge generation material.In the case of a zero-dispersion type, the amount is preferably 0.1 to 20.0% by weight based on the charge transport material. It is preferable to add 1 to 5.0% by weight of O.

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 photosensitive FF coating.

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. Examples of such resins, which are preferably resins with high properties, include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon, and methoxymethylated nylon, polyurethane, and melamine resins. Examples include curable resins that form a three-dimensional network structure, such as phenol resins and epoxy resins.

Further, in order to prevent moiré, reduce residual potential, etc., fine powder pigments of metal compounds such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the intermediate layer.

Examples of the solvent or dispersion medium 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,
Examples include butyl acetate, dimethyl sulfoxide, and the like.

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 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 Aluminum drum with a diameter of 80 mm and a length of 340-I Alcohol-soluble nylon resin (CM-8000, nylon 6/66/610/12 copolymer, manufactured by Toshi Co., Ltd.) 10
A coating solution consisting of 190 parts by weight of 6 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 created. 1! In A, 4 parts by weight of polyvinyl butyral resin (XYHL: Union Carbide Co., Ltd.) was dissolved in 150 parts by weight of cyclohexanone, and exemplified compound no.

10 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 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 provide a charge generation layer with a thickness of 0.2-. ), 10 parts by weight of polycarbonate resin (Panlite, 1300; manufactured by Teijin Chemicals), 0.002 parts by weight of silicone oil (KF-50: 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 20μ. 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 7 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(9), (60), and (69) 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 8 Example 1 except that 0.04 parts by weight of 2,5-di-tert-butylhydroquinone was added to the charge transport layer of Example 1, and 2,5-di-tert-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 negatively charged photoreceptors, and the developing device was removed and a surface electrometer was installed in it to evaluate the potential.

Surface potentials were measured at the initial stage and after 20,000 copy processes using the modified FT-5510. The results are shown in Table-1.

Table-1 Example 9 8 parts by weight of the charge transport substance used in Example 1, 1 polycarbonate resin (Panlite -1300; manufactured by Teijin Chemicals)
A charge transport layer coating solution was prepared by dissolving 0.002 parts by weight of silicone oil (KF-50; Shin-Etsu Chemical Co., Ltd.) in 85 parts by weight of methylene chloride. This was applied by dip coating onto an aluminum drum with a diameter of 80 mm and a length of 340 mm.

Zero-order polycarbonate resin (Panlite L) was dried at 120°C for 15 minutes to form a charge transport layer with a thickness of 20 mm.
-1250. 4 parts by weight (manufactured by Teijin Kasei Co., Ltd.) was dissolved in 150 parts by weight of cyclohexanone, and exemplified compound no.

Add 1.2 parts by weight of the disazo pigment (13) and disperse in a ball mill for 48 hours, and then add 210 parts by weight of cyclohexanone.
Parts by weight, 3 parts by weight of the charge transport substance represented by the structural formula (a) and 0.015 parts by weight of 2,5-di-tart-butylhydroquinone 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 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 μs, thereby preparing a photoreceptor for electrophotography of the present invention.

Comparative Example 4 A photoreceptor was prepared in the same manner as in Example 9 except that 2,5-di-tart-butylhydroquinone was removed from the charge generation layer of Example 9.

Next, Example 9. F was obtained by removing the developing section from the photoreceptor obtained in Comparative Example 4 and modifying it so that a surface electrometer could be attached to it.
It was attached to T5510 (manufactured by Ricoh), and the surface potential was measured and evaluated at the initial stage and after the 2000 copy process.

The results are shown in Table-2.

Table-2 Patent applicant Ricoh Co., Ltd. - Procedural amendment 1, Indication of the case Patent application No. 22645 of 1988 2, Name of the invention Electrophotographic photoreceptor 3, Person making the amendment Relationship to the case Patent applicant residence Address: 1-3-6 Nakamagome, Ota-ku, Tokyo Name:
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 8. Contents of amendment The following amendments will be made to the specification of this application.

(1) "Separate type" in the second line from the bottom of page 41 will be corrected to "distributed type."

(2) On page 43, line 10, "it is preferable to contain" was replaced with "it is preferable to contain, and the film thickness is 0.
5-10. "It is preferable to do so."

(3) Page 47, line 6, “Light=1300J,”
I will correct it to 11300J for the light.

(4) "Thickness 20++v+J" on page 50, line 8 is corrected to "thickness 2G, J.

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, the charge-generating substance is represented by the following general formula (I) or general formula (II).
An electrophotographic photoreceptor characterized in that the compound represented by the above is used, and the photosensitive layer contains a hydroquinone compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, Ar_1, Ar_2, Ar_3, Ar_4, or Ar_5 is a substituted or unsubstituted carbocyclic aromatic group. residue or heteroaromatic residue, A and A' are phenolic O
Coupler residues having H groups are R_1, R_2, R_3
, R_4, R_5 and R_6 represent a hydrogen atom, a substituted or unsubstituted alkyl group, an aralkyl group, or an electron-withdrawing group such as a cyano group, halogen, or nitro group. )