JPH03101738A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body which is free from an increase in residual potential and has excellent electrostatic charge stability even after repetitive use for a long period of time by incorporating a specific polyhydroxyflavn compd. into a photosensitive layer. CONSTITUTION:The polyhydroxyflavan compd. expressed by formula I is incorporated into the photosensitive layer contg. a charge generating material and charge transfer material on a conductive substrate. In the formula I, R1 to R7 respectively denote a hydrogen atom, hydroxy group, halogen atom, alkyl group, alkenyl group, aryl group, cycloalkl group, alkoxy group, substed. amino group, imino group, heterocyclic group, alkylthio group or acyl group. At least one of R3 to R7 are a hydroxy group. Thus, the electrophotographic sensitive body which has the excellent electrostatic charge stability and is free from the increase in the residual potential even after the repetitive use, i.e. free from the degradation in image density and scumming, and has a long life and high reliability is obtd..

Description

[Detailed Description of the Invention] [Industrial Field] The present invention 1jJJ relates to electrophotographic photoreceptors, and has excellent charging stability, with no increase in residual potential, especially during repeated use over a long period of time. 6 Regarding Electrophotographic Photoreceptors [Prior Art] Inorganic materials such as selenium, cadmium sulfide, and sulfur 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 and the manufacturing conditions. For example, selenium tends to crystallize due to heat, dirt, etc., and its properties tend to deteriorate. In addition, it has drawbacks such as manufacturing cost, impact resistance, toxicity, and other issues that require careful handling.

Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Zinc oxide is also moisture resistant, II
It has the disadvantage of poor durability. In contrast to electrophotographic photoreceptors using these inorganic photoconductive materials, photoreceptors using organic photoconductive materials are being actively researched due to their light weight, ease of film formation, manufacturing cost, and wide variation as organic compounds. Development is underway. for example,
Initially, photoreceptors containing polyvinyl rubazole and 2,4,7-trinitro-9-fluorenone as described in Japanese Patent Publication No. 50-10496, and polyvinyl rubazole as described in Japanese Patent Publication No. 48-25658 with a pyrylium salt dye. A sensitized photoreceptor or a photoreceptor based mainly on a conjugate complex has been proposed. However, these photoreceptors are not up to par in terms of 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 as a charge-generating substance.
As described in the publication, the charge transport material is JP-A-58-198.
043, Japanese Patent Application Laid-Open No. 199352, etc. are known. However, even these function-separated type photoreceptors are not particularly satisfactory in terms of durability, and in recent years, there has been an increasing demand for durability. With the increase in charging stability, ensuring charging stability has become an issue that cannot be ignored. In other words, when the chargeability decreases,
In copying machines, this causes low image density when copying, and in laser printers that use a reversal development method, it causes deterioration in PLJ image quality, such as background stains. In order to solve these problems, it has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, if a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize the charging property, although the charging property will improve,
It has the drawbacks of decreased photosensitivity and increased residual potential. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, charging stability will be insufficient.

On the other hand, when a photoreceptor is actually used in a copying machine, it is exposed to ozone generated by a corona charger. From the viewpoint that this ozone oxidizes the charge transporting substance etc. in the photosensitive layer, causing a decrease in sensitivity, an increase in residual potential, or a decrease in charging potential, Japanese Patent Application Laid-Open No. 122444/1982 and No. 156052/1989 are published. The addition of an antioxidant to the photosensitive layer as seen in JP-A-63-13
A proposal has been made in which a gas barrier resin layer is provided on the charge transport layer as seen in Japanese Patent No. 5955. However, even with the above measures, there are drawbacks such as an increase in residual potential, a decrease in sensitivity, and insufficient improvement in durability, and a satisfactory photoreceptor has not yet been obtained. .

[Problem to be solved by the invention]

The present invention solves the above-mentioned conventional problems. Specifically, the present invention has excellent ozone resistance, excellent charging stability even after repeated use, and no increase in residual potential, which means that it does not reduce image density or cause background stains. The object of the present invention is to provide an electrophotographic photoreceptor that can give good images without causing image formation.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support, a polyhydroxyflavan compound represented by the following general formula (N) is incorporated in the photosensitive layer. An electrophotographic photoreceptor characterized by containing (in the formula, 1 {1 to R, respectively, a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxy group, represents a substituted amino group, imino group, heterocyclic group, alkylkio group, or acyl group (provided that at least one of R1 to R7 is a hydroxy group).The electrophotographic photoreceptor of the present invention Since the photosensitive layer contains a polyhydroxyflavan compound, it has excellent charging stability even after repeated use, and the residual potential does not increase. Therefore, it has a long life and high reliability with no decrease in image density or background smearing. .

Specific examples of polyhydroxyflavan compounds that can be used in the present invention include compounds as shown below.

The electrophotographic photoreceptor of the present invention is. The above general formula [! ] By incorporating the polyhydrosyfurapane compound shown in the photosensitive scrap into the photosensitive scrap, it becomes highly durable.The reason for this is not clear at present, but the photosensitive material, especially the binder resin, It has excellent compatibility with other photosensitive layer constituents, it does not react with other materials constituting the photosensitive layer, it does not act as a trap for charge carriers, and it has the ability to quickly react with radical substances and prevent the formation of traps. Examples include being excellent. In the present invention, it is preferable to further add a secondary deterioration inhibitor to the polyoxyflavan compound from the viewpoint of improving storage stability and heat resistance.

Although phosphorus compounds and sulfur compounds are well known as secondary deterioration inhibitors, it is particularly preferable to use phosphorus compounds. Specific examples of phosphorus compounds include tris(nonylphenyl)phosphite, tris(p-te
rt-octylphenyl) phosphite, L-lis(2,
4.6-tris(α-phenylethyl)]phosphite, tris(p-2-butenylphenyl)phosphite,
Bis(p-nonylphenyl)cyclohexyl phosphite, tris(2,4-di-tert-dibutylphenyl) phosphite, di(2,4-di-tert-dibutylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite ,4,4
'-Isopropylidene-diphenol alkyl phosphite, Te1-latridecyl-4,4'-butylidene-bis(3-methyl-6-tert-butylphenol) diphosphite, Tetrakis(2,4-di-tert-butylphenyl)-4 .4'-biphenylene diphosphite, 2,6-di-tert-butyl-4-methylphenyl phenyl pentaerythritol diphosphite,
2,6-di-tert-butyl-4-methylphenyl
Methyl pentaerythritol diphosphite, 2,
6-di-tert-butyl-4-ethylphenyl stearyl pentaerythritol diphosphite, di(2
,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,6-di-tert-butyl-4-methylphenyl)
Examples include rt-amyl-4-methylphenyl, phenyl, pentaerythritol diphosphite, and two or more of these compounds may be used in combination.

As the charge generating substance that can be used in the electrophotographic photoreceptor of the present invention, both inorganic and organic substances can be used as long as they absorb light and generate charge carriers.

Examples of the pyrophoric material include amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, zinc oxide, and amorphous silicon.

Examples of organic substances include phthalocyanine pigments such as metal-capturing cyanine and non-metallic capping-cyanine, azulenium salt pigments, methine squarate pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, and diphenylamine. Azo pigments having a skeleton, azo pigments having a dibenzothiophene skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a fluorenone skeleton, azo pigments having a bisstilbene skeleton, azo pigments having a distyryl oxadiazole skeleton,
Azo pigments having a distyrylic rubazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments, penzoquinone and naphthoquinone pigments,
Cyanine and azomethine pigments, indigoid pigments,
Examples include bisbenzimidazole materials.

Examples of charge transport materials that can be used in the electrophotographic photoreceptor of the present invention include poly-N-vinyl Rubazole and its derivatives, poly-γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, Polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imizole derivatives, triphenylamine derivatives. 9-(p-diethylaminostyryl)anthracene, 1,l-bis-(4-dibenzylaminophenyl)propane, styryl anthracene, styryl pyrazoline ζ
Examples include phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, penzofuran derivatives, penzimidazole derivatives, and thiophene derivatives.

Among these, aromatic amine compounds represented by the general formula (■) are particularly preferred.

? In the formula, R■ and 83 represent a substituted or terminally substituted aromatic ring group selected from a phenyl group, a naphthyl group, and a polyphenyl group, and R3 represents a substituted or terminally substituted aryl group, alkyl group, alkoxy group, or heterocyclic group. The formula represents an aromatic group. ) The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a single layer type or a functionally separated type by combining an electric current generation layer and a charge transport layer.

In the case of a single 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, but a positively charged type In this case, the charge generation layer and the charge transport layer may be stacked in reverse order. In the case of a functionally separated type, a charge transport substance may be contained in the charge generation layer. In particular, in the case of a positively charged structure, the sensitivity is improved.

Further, an intermediate layer may be provided between the photosensitive layer and the substrate in order to improve adhesion and charge processing properties. Furthermore, protective dust may be provided on the photosensitive layer in order to improve mechanical durability such as abrasion resistance. Binders used in forming the charge generation layer, charge transport layer and dispersed photosensitive layer include polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, Phenol resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicone resin, polyvinyl rubber, 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 kinds.

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

In the case of a negative charge type (laminated substrate/electric charge generating layer/electron transport layer), in the charge generation 89, the ratio of the binder to the charge generating substance is 0 to 400 by weight2, and the membrane Iv is 0. 1~5μ
Japanese is preferred. In charge transport J-ke, the ratio of charge transport substance to binder is 20 to 200% by weight. The thickness of the film J1 is preferably 5 to 50 μm.

In the case of a positively charged type (laminated substrate/charge transport M/charge generation layer), 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 μm.
The charge generating layer preferably contains 10 to 500 parts by weight of the charge generating substance based on the binder. Furthermore, the charge generation layer contains a charge transport substance.
It is preferable to include it, and its inclusion has the effect of suppressing residual potential and improving sensitivity. In this case, it is preferable that the charge transport material is contained in an amount of 20 to 200% by weight of the binder.

Note that the film/'X is preferably 0.1 to 10 pm. In the case of a single layer type, the ratio of the charge transport substance and the charge generation substance to the binder is 50 to 150ffi4a% and 10 to 50%, respectively.
It is preferable that the weight is i%<1, and the thickness is preferably 5 to 50 μm.

In addition, the amount of the polyhydroxyflavan compound of the present invention to be added to the photosensitive layer is 0.00% relative to the charge transport material when it is added to the charge transport layer in the case of a functionally separated type. It is preferable that it is 10.0% by weight. When added to the charge generation layer, it is preferably added in an amount of 0.1 to 20.0% by weight based on the charge generation material. In the case of a dispersed type, it is preferable to add 0.01 to 5.0 weight 2 to <t r:i transport substance.

If the amount of the polyhydroxyflavan compound represented by the general formula CI) is less than the lower limit, the effect of increasing durability cannot be obtained, and if it is more than the upper limit, it will cause adverse effects such as decreased sensitivity.

In the case of a functionally separated type photoreceptor, the polyhydroxyflavan compound used in the present invention is used in charge generation JH. It may be added to any charge transport layer. This is considered to be because the polyhydroxyflavan compound used in the present invention is actively diffused into other layers by the coating liquid dispersion medium or solvent during coating of the photosensitive layer.

The interlayer provided as necessary is generally made of resin as its main component, but considering that the photosensitive Rl is applied thereon with a solvent, these resins are solvent resistant 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; polyurethane; melamine resins; phenolic resins; alkyd-melamine resins; Examples include curable resins that form a three-dimensional network structure, such as epoxy resins.

Further, 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. Also, as a solvent or dispersion medium used in forming the charge generation layer and charge transport layer. N,N'-dimethylformamide, ace-1hen,
Methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, dichloromethane, monochlorobenzene, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, etc. ;S can be thrown.

The photosensitive layer may 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, aluminum,
Examples include sheet-like or cylindrical substrates made of plastic, paper, etc., which have been treated to be conductive by vapor-depositing metals such as nickel, or by coating conductive substances such as titanium oxide, tin oxide, carbon black, etc. together with a suitable binder. ．． [
[Effects of the Invention] 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 l Alkyd resin [Beccosol 1307-60-EL (
Dainippon Ink Chemical Industry Co., Ltd.! )) 15 parts by weight, 10 parts by weight of melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink & Chemicals)], 1 part by weight of methyl ethyl ketone
To this was added 90 parts by weight of titanium oxide powder [Tiepeke CR-EL (manufactured by Ishihara Sangyo Co., Ltd.)] and dispersed in a ball mill for 12 hours to prepare a coating solution for an intermediate layer.

This was applied to an aluminum plate (A1080 (manufactured by Sumitomo Light Metals)) with a thickness of 0.20, and dried at 140° C. for 20 minutes to form an intermediate layer with a thickness of 2 μm.

Next, polyvinyl butyral resin [S-LEC BL-S (
(manufactured by Sekisui Chemical Co., Ltd.)] 4 parts by weight of cyclohexane 15
0 parts by weight, and then polycarbonate resin shown in the following structural formula (a) [Panlite K-1300
(Teijin Kaorisha i!!2) and 0.002 parts by weight of silicone oil (KF-50 (Shin-Etsu Chemical Co., Ltd.'!M)) were dissolved in 83 parts by weight of tetrahydrofuran, and the following structure was added to this. Add 7 parts by weight of the charge transport substance shown in formula (b) and 10 parts by weight of the triazo pigment, and mix 48 parts by weight with a ball mill.
After time dispersion, 210 parts by weight of cyclohexanone was further added and dispersion was carried out for 3 hours. This was taken out into a container and cyclohexanone was diluted so that the solid content was 1.5% by weight. The charge generation layer coating liquid thus obtained was applied onto the intermediate layer and dried at 130° C. for 20 minutes to form a charge generation layer having a thickness of 0.2 μm.

A charge transport coating liquid was prepared by adding and dissolving 0.07 parts by weight of a polyhydroxyflavan compound of the exemplified compound Ncil. This was applied onto the charge generation layer and dried at 130° C. for 20 minutes to form a charge transport layer with a thickness of 20 μm.

The electrophotographic photoreceptor of Example 1 was produced in the manner described above.

Examples 2 and 3 Example 2 was carried out in the same manner as in Example 1 except that exemplified compound N (128 and 66 polyhydroxyflavan compounds were used in place of exemplified compound Nα1).
, 3 electrophotographic photoreceptors were created.

Comparative Example 1 An electrophotographic photoreceptor of Comparative Example 1 was prepared in the same manner as in Example 1 except that the polyhydroxyflavan compound of the exemplified compound Nnl was not added.

Comparative Examples 2 to 4 In Example 1, Comparative Compound 1.2 shown below was used instead of the polyhydroxyflavan compound of Exemplary Compound Nα1.
Electrophotographic photoreceptors of Comparative Examples 2 and 3.4 were prepared in the same manner as in Example 1 except that 0.07 parts by weight of each of Comparative Compound 1 (Sumilyzer-MOP-S: manufactured by Sumitomo Chemical Co., Ltd.) was added. ) Comparative Compound 2 (Sumilyzer TPM: manufactured by Sumitomo Chemical Co., Ltd.) CH20H, COOC. ．． H,, PoS t CH yo CH2C00C14H29 Comparative compound 3 (MARK PEP-24: manufactured by Adeka Argus) Example 4 3 parts by weight of alcohol-soluble polyamide (CM-8000 (manufactured by Toray Industries)) was mixed with MeOH/n-BuOH: 8 / 2 was heated and dissolved in 100 parts by weight of a mixed solvent to create an intermediate layer coating solution, which was coated on an aluminum plate with a thickness of 0.21 lm (
AI (180 (manufactured by Sumitomo Light Metal)), Kyoto cloth, 120℃1
After drying for 0 minutes, an intermediate layer having a thickness of 0.2 μm was formed.

Next, 4 parts by weight of polyvinyl butyral resin (XYIIL; manufactured by Union Carbide) was dissolved in 150 parts by weight of cyclohexanone, and 10 parts by weight of a disazo pigment represented by the following structural formula (c) was added to the solution by a ball mill for 48 parts by weight. time dispersion,
Furthermore, cyclohexanone 210 weight 11. A ball mill test was performed 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 generating JVi coating solution thus obtained was dip coated onto the intermediate layer, and
After drying for 0 minutes, a charge generation/M layer with a thickness of 0.2 μm was provided.

Next, polycarbonate 1 to resin [Panlite K-130
0 (Teijin Kaisha 'I3)] and 0.002 parts by weight of silicone oil (KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)) were dissolved in 85 parts by weight of tetrahydrofuran and 7 parts by weight, and the lower V2 structure was dissolved in this. 9 parts by weight of the charge transport substance shown in formula (d) and the polyhydroxyflavan compound of the exemplary compound Nal were added to 0
．． 09 parts by weight were added and dissolved to prepare a charge transport layer coating solution. This was applied to the charge generation layer 2 and dried at 130° C. for 20 minutes to form a charge transport layer having a thickness of 20 μm, thereby producing an electrophotographic photoreceptor of Example 4.

Examples 5 and 6 Electrophotographic photoreceptors of Examples 5 and 6 were produced in the same manner as in Example 4, except that polyhydroxyflavan compounds of exemplified compounds Na28 and Nα66 were used in place of exemplified compound Nαl, respectively. Created. Comparative Example 5 An electrophotographic photoreceptor of Comparative Example 5 was prepared in the same manner as in Example 4, except that the polyhydroxyflavan compound of exemplified compound Nnl was not added.

Comparative Examples 6 to 8 In Example 4, Comparative Compounds 1, 2, .
Electrophotographic photoreceptors of Comparative Examples 6 and 7.8 were produced in the same manner as in Example 4, except that 0.09 parts by weight of each of Comparative Examples 3 and 3 were added.

The electrostatic properties of the electrophotographic photoreceptor obtained as described above were measured using a dynamic method using SP-428 (manufactured by Kawaguchi Electric Seisakusho).First, it was charged with an applied voltage of -6 KV for 20 seconds, and then darkened for 20 seconds. Exposure was performed for 30 seconds to attenuate and further increase the surface illumination to 61ux.The charging potential was the surface potential V2 (-V) after 2 seconds of charging, and the sensitivity was as the surface potential changed from -800V to -80V after exposure. The exposure amount E■/■.(1ux-SeC) required to
The surface potential was measured after seconds.

Thereafter, after irradiation with 51 μs of tungsten light with a color temperature of 2856K and repeated fatigue of charging at -6KV for 3 hours, the same procedure as before was performed to obtain v, (-v), E■/1.
(1ux・see),■,. (1 V) was measured.

Example 7 An intermediate layer was formed on an aluminum plate in the same manner as in Example 1, and the charge transport layer coating solution shown in Example 1 was applied onto the intermediate layer by dip coating and dried to form a film JV. 20μ
A charge transport layer of m was created. Next, two parts by weight of a polycarbonate resin (Panlite L-1 250, Teijin Kasei H) was dissolved in a mixed solvent of 150 parts by weight of tetrahydrofuran, and 3 parts by weight of the trisazo pigment having the structural formula (a) above was added thereto and the mixture was placed in a ball mill. He lost 48 hours. Further, this dispersion was added with 7 parts by weight of the charge transporting substance shown in the structural formula (b) and 300 parts by weight of cyclohexanone in a ball mill.
It was allowed to stand for 4 hours and dissolved to create a coating solution for the charge generation layer. This was spray coated on the charge transport layer and dried to form a film J1.
A charge generation layer of 3PI1 was provided to prepare an electrophotographic photoreceptor.

Example 8 In Example 7, exemplary compound I included in charge transport
An electrophotographic photoreceptor of Example 8 was prepared in the same manner as in Example 7 except that the polyhydroxyflavan compound of Exemplary Compound No. 2g was used instead of the polyhydroxyflavan compound of JQI.

Comparative Example 9 An electrophotographic photoreceptor of Comparative Example 9 was prepared in the same manner as in Example 7 except that the polyhydroxyflavan compound of the exemplified compound &l contained in the charge transport layer was removed.

Comparative Example 10.11 Example 7 except that 0.07 parts by weight of Comparative Compound 1.3 was added in place of the polyhydroxyflavan compound of the exemplified compound Nαl contained in the charge transport layer. Electrophotographic photoreceptors of Comparative Example 10.11 were produced in the same manner. Examples 7 and 8 and Comparative Examples 9 and 10 obtained as above. The electrostatic properties of Sample No. 11 were evaluated in the same manner as the evaluation method of the electrophotographic photoreceptor of Example 1, except that the applied voltage for charging was +6 KV and the potential was evaluated as positive.

The evaluation results are shown in Table 2.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer containing a charge generating substance and a charge transporting substance on a conductive support, the photosensitive layer contains a polyhydroxyflavan compound represented by the following general formula [I]. An electrophotographic photoreceptor characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R_1 to R_7 are each a hydrogen atom, hydroxy group, halogen atom, alkyl group, alkenyl group, aryl group, cycloalkyl group, alkoxy group, substituted amino group, imino group, heterocyclic group, alkylkio group, or acyl group, provided that at least one of R_3 to R_7 is a hydroxy group.)