JP2002049163A - Manufacturing method of electrophotographic photoreceptor - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing an electrophotographic photosensitive member that achieves high image quality, long life, and high reliability at a high level, and particularly has excellent image reproducibility, durability, and light sensitivity. Another object of the present invention is to provide a method of manufacturing an electrophotographic photoreceptor which is excellent. SOLUTION: In the method for producing an electrophotographic photosensitive member, in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive support, the intermediate layer is formed with two kinds of intermediate layers each containing an inorganic compound having a different average particle size. A method for producing an electrophotographic photoreceptor, wherein a coating film is formed simultaneously by two spray heads using a coating liquid for use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a method for producing an electrophotographic photosensitive member used in an electrophotographic process such as a facsimile, a laser printer, and a direct digital plate making machine. More specifically, the present invention relates to an electrophotographic photosensitive member having high sensitivity, high image quality, and excellent durability. And a method for producing the same.

[0002]

2. Description of the Related Art An electrophotographic method using an electrophotographic photosensitive member applied to a copying machine, a facsimile, a laser printer, a direct digital plate making machine, and the like means at least a primary charge, an image exposure, and a development of the electrophotographic photosensitive member. After the process, the method includes a process of transferring and fixing a toner image to an image holding member (transfer paper), and cleaning the surface of the electrophotographic photosensitive member.

The basic characteristics required of an electrophotographic photoreceptor in this electrophotographic method include that it can be charged to an appropriate potential in a dark place and that there is little dissipation of electric charge in a dark place. It can be dissipated. Further, in addition to these characteristics, long-term reliability such as image quality characteristics, low pollution, low cost, and the like are required.

[0004] The electrophotographic photosensitive member basically comprises a support and a photosensitive layer formed on the support. As the support, a metal having high conductivity is often used, and among them, aluminum or an aluminum alloy is often used. On these surfaces, there are structural defects such as protrusions and foreign substances, oils such as rust-preventive oils and chemical impurities, and the like. If the photosensitive layer is provided on the support as it is, image defects will occur. Cannot be used.

As one technique for solving this problem, it has been proposed to provide an intermediate layer between a conductive support and a photosensitive layer and then provide a photosensitive layer. Examples thereof include a resin layer provided on a conductive support, and an intermediate layer in which an inorganic pigment (titanium oxide, tin oxide, etc.) is dispersed in a resin (Japanese Patent Application Laid-Open No. 61-204642, etc.). It has been known.

This method has been applied to many photoconductors because of its relatively low cost and good effect. However, in the conventional intermediate layer of resin alone, or in an electrophotographic photosensitive member having an intermediate layer in which an inorganic pigment is dispersed in the resin, it can not be said that there is no problem in electrostatic repetition characteristics, There has been a problem that the electrophotographic characteristics are deteriorated, particularly the charging potential is reduced, and the surface potential is reduced during the time from charging to development, that is, so-called dark decay is increased. Even when there is no problem in the electrostatic electrophotographic characteristics, when an image is formed through an electrophotographic process such as a general Carlson process or a similar process, image defects called white spots and black spots may occur. It often occurred.

Therefore, these conventional photoconductors are still insufficient in stability of image quality when used repeatedly. That is, charging stability, light sensitivity, and image quality are all satisfied,
Further, an electrophotographic photoreceptor having these characteristics for a long period of time has not been obtained. In other words, the conventional electrophotographic photoreceptor is insufficient to achieve the high performance, long life, and high reliability required of the electrophotographic engine in recent years, and improvement has been strongly desired.

[0008] In addition, there is a problem in the method of manufacturing the above-mentioned photoreceptor. In general, there are two methods for producing an electrophotographic photosensitive member, a dry film forming method and a wet coating method. However, most of organic electrophotographic photoreceptors other than selenium-based and amorphous silicon-based photoreceptors are mostly manufactured by wet coating methods such as dip coating, spraying, and roller coating. Is done. This wet coating method has advantages such as easy area enlargement and inexpensiveness, but the properties (viscosity,
It also has the disadvantage of being susceptible to the effects of surface tension, etc.) and the support (including the substrate). Recent electrophotographic photoreceptors are required to have high durability or high quality, and various materials have been used, and many materials insoluble in solvents are also used. In such a case, it is generally used as a dispersion, but the dispersion is generally not stable. In particular, as described above, materials such as inorganic compounds that are used for the intermediate layer and have a fine particle size crushed to the submicron order may interact with organic solvents, causing problems such as aggregation and sedimentation. When such a problem occurs in the coating liquid for forming an intermediate layer, it leads to a coating film defect of a photoreceptor to be produced, and eventually causes a defective image. Therefore, how to apply and form a dispersion liquid is an important issue. In other words, it is no exaggeration to say that the quality of the coating film and, consequently, the image quality is determined by the quality of the coating liquid and the coating method.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an electrophotographic photosensitive member which achieves high image quality, long life and high reliability at a high level. It is an object of the present invention to provide a method for producing an electrophotographic photoreceptor having excellent properties and photosensitivity.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that an intermediate layer and a photosensitive layer are sequentially formed on a conductive support. A production method characterized in that two intermediate layers each containing an inorganic compound having a different average particle size are coated and formed simultaneously by two spray heads using two types of coating liquids for an intermediate layer. Coating liquid 2 containing compound
It was found that a stable coating film could be obtained by separately preparing the two and performing the coating simultaneously. Moreover, the respective liquids can be set so that the disperse system does not collapse due to mixing, and the pot life is extended without causing a change such as aggregation.

By adopting such a form, the range of choice of materials has been widened, and it has become possible to design a higher-performance and higher-quality photoconductor. Further, each of the two intermediate layer forming coating liquids is composed of an inorganic pigment and a binder resin, and the average particle diameter of the inorganic compound contained in one intermediate layer forming coating liquid is D ₁ , and the other is When the average particle size of the inorganic compound contained in the coating liquid for forming a layer is D ₂ , the relationship of D ₂ / D ₁ ≤ 1/5 is satisfied, and the above-mentioned object is achieved by the method for producing an electrophotographic photoreceptor. Was achieved.

The electrophotographic photosensitive member used in the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of the electrophotographic photoreceptor of the present invention. The electrophotographic photoreceptor includes a conductive support 21, an intermediate layer 25 in contact with the conductive support 21, and a photosensitive layer including a charge generation layer 31 and a charge transport layer 33. 23 are formed.

First, the conductive support 2 used in the present invention
1 will be described. Conductive support 2 used in the present invention
As 1, a material exhibiting conductivity of 10 ¹⁰ Ω or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum and iron, an oxide such as tin oxide and indium oxide, A film or cylindrical plastic or paper coated by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. I. , I. I. Pipes that have been surface-treated by cutting, superfinishing, polishing, or the like can be used after forming into a raw tube by a method such as extrusion, drawing, or the like.

Next, the intermediate layer 25 used in the present invention will be described. The intermediate layer used in the present invention is formed with an inorganic compound and a binder resin as main components, and the resin used in the present invention is a general organic compound in consideration of coating a photosensitive layer thereon with a solvent. It is desirable that the resin has high solvent resistance to the solvent. As such a resin,
Polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymer-soluble nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resin, phenolic resin, alkyd resin,
A curable resin that forms a three-dimensional network structure, such as an epoxy resin, may be used. In particular, when an alkyd resin and a melamine resin are used, a film excellent in characteristics can be obtained.

Examples of the inorganic compound used in the present invention include metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide. These are finely divided by a pulverizing method such as a ball mill. Powdered material is used.

According to the present invention, in an electrophotographic photosensitive member manufacturing method in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive support, the intermediate layer is formed by two kinds of intermediate layers each containing an inorganic compound having a different average particle size. According to a production method characterized in that a coating film is formed simultaneously with two spray heads using a coating liquid for forming a layer, the two types of coating liquids for forming an intermediate layer are both inorganic compounds, The average particle diameter of the inorganic compound contained in one intermediate layer forming coating liquid was D ₁ , and the average particle diameter of the inorganic compound contained in the other intermediate layer forming coating liquid was D ₂ . In this case, the relationship of D ₂ / D ₁ ≤ 1/5 may be satisfied, but preferably, the condition satisfying the above relationship is such that one inorganic compound has an average particle size of 0.1 μm or less, and the other inorganic compound has an average particle size of 0.1 μm or less. Is preferably 1 μm or less.

Next, the photosensitive layer 23 in the present invention will be described. The photosensitive layer 23 is responsible for charge generation and charge transport in one layer,
A so-called single-layer structure or a stacked structure in which charge generation and charge transport are performed by different layers may be used. Here, a stacked structure in which charge generation and charge transport are respectively performed by different layers will be described.

First, the charge generation layer 31 which is responsible for charge generation will be described. The charge generation layer 31 is a layer containing a charge generation substance as a main component, and may use a binder resin as needed. Known materials can be used as the charge generating substance. For example, metal phthalocyanines such as copper phthalocyanine and iron phthalocyanine, phthalocyanine-based pigments such as metal-free phthalocyanine, azulhenium salt pigments, methine squaric acid pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, diphenylamine Azo pigments having a skeleton, azo pigments having a dibenzothiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bisstilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, Azo pigments having a styrylcarbazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone Pigments, cyanine and azomethine pigments, indigoid pigments, and bisbenzimidazole pigments. These charge generating substances can be used as a mixture of two or more kinds.

The binder resin used as needed for the charge generation layer 31 includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-
N-vinyl carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more.

The method for forming the charge generation layer 31 includes a vacuum thin film preparation method and a casting method from a solution dispersion system. In the former method, a vacuum deposition method or the like is used, and a good formation can be achieved. Further, in order to provide a charge generation layer by a casting method described below, a ball mill using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with the binder resin if necessary for the inorganic or organic charge generation material described above,
It can be formed by dispersing with an attritor, a sand mill or the like, diluting the dispersion liquid appropriately and applying. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, and preferably 0.05 to 2 μm.

Next, the charge transport layer 33 will be described.
The charge transporting layer 33 can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying this on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transport material includes a hole transport material and an electron transport material. Examples of the electron transporting substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
And other known materials such as styryl anthracene derivative, pyrazoline derivative, divinylbenzene derivative, hydrazone derivative, indene derivative, butadiene derivative, pyrene derivative, bisstilbene derivative, enamine derivative and the like. These charge transport materials are used alone or in combination of two or more.

Examples of the binder resin for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride-vinyl acetate. Polymer, polyvinyl acetate, polyvinylidene chloride, polyalate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic or thermosetting resins such as melamine resin, urethane resin, phenol resin, and alkyd resin can be used. These binder resins can be used alone or as a mixture of two or more.

The amount of the charge transporting substance is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight are appropriate. As the solvent used here,
Tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 33.

As the plasticizer, those used as general plasticizers for resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is 0.1 to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used, and the amount used is based on 100 parts by weight of the binder resin. About 0.01 to 1 part by weight is appropriate. Further, in the present invention, an antioxidant can be added for the purpose of improving environmental resistance, especially for the purpose of preventing a decrease in sensitivity and an increase in residual potential.
The antioxidant may be added to any layer containing an organic substance, but good results can be obtained by adding it to a layer containing a charge transporting substance.

The antioxidants that can be used in the present invention include the following. Monophenolic compound 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t −
(Butyl-4-hydroxyphenyl) propionate and the like.

Bisphenolic compounds 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-
Ethyl-6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-t-butylphenol),
4,4'-butylidenebis- (3-methyl-6-t-butylphenol) and the like.

High molecular phenolic compound 1,1,3-tris- (2-methyl-4-hydroxy-
5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-
4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy -3'-t-butylphenyl) butyric acid] glycol esters, tocophenols and the like.

Paraphenylenediamines N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-
Phenylenediamine, N, N'-di-isopropyl-p
-Phenylenediamine, N, N'-dimethyl-N, N '
-Di-t-butyl-p-phenylenediamine and the like.

Hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t
-Octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone and the like.

Organic sulfur compounds Dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like.

Organic phosphorus compounds: triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

These compounds are known as antioxidants for rubber, plastics, oils and the like, and commercially available products can be easily obtained.

The amount of the antioxidant added in the present invention is 0.1 to 100 parts by weight, preferably 2 to 30 parts by weight, based on 100 parts by weight of the charge transporting substance. Further, the thickness of the charge transport layer is preferably about 5 to 100 μm.

[0038]

Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples. All parts used in the examples are parts by weight.

Example 1 A coating liquid 1 for an intermediate layer, prepared as described below, on an aluminum drum of φ30 mm as a conductive support,
Using the coating liquid 2 for the intermediate layer, each coating liquid is simultaneously applied so as to have a discharge amount of 1: 1 and dried by using two spray heads, and the intermediate layer having a film thickness of 3 μm is formed. Provided. Next, using a coating liquid for a charge generation layer and a coating liquid for a charge transport layer as described below, coating was sequentially performed by a dip coating method, followed by drying and drying of a 0.2 μm charge generation layer, 21.2 μm.
A μm charge transport layer was formed to obtain an electrophotographic photosensitive member of the present invention. [Coating Liquid 1 for Intermediate Layer] Titanium oxide powder [Taipeku CR-EL (Ishihara Sangyo)] 60 parts Alkyd resin [Beccolite M6401-50 (Dainippon Ink & Chemicals)] (Solid content 50%) 12 parts Melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content: 60%) 7 parts Methyl ethyl ketone 1621 parts Cyclohexanone 648 parts The above components were mixed, ball milled, and the average of the above titanium oxide powder was obtained. The dispersion conditions were adjusted so that the particle diameter became 0.5 μm, and the coating liquid for an intermediate layer 1 was obtained. [Coating liquid 2 for intermediate layer] Titanium oxide powder [TTO-55 (N) (manufactured by Ishihara Sangyo)] 50 parts Alkyd resin [Beccolite M6003-50 (manufactured by Dainippon Ink and Chemicals)] (solid content: 50%) 10 parts Melamine resin [Super Beckamine J-820-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content: 60%) 6 parts Methyl ethyl ketone 1535 parts Cyclohexanone 542 parts The dispersion conditions were adjusted so that the average particle diameter of the above was 0.06 μm, to obtain a coating liquid 2 for an intermediate layer. [Coating liquid for charge generation layer] The following components were mixed and dispersed by a ball mill. Metal-free phthalocyanine pigment [Fastgen Blue 8120B (manufactured by Dainippon Ink and Chemicals, Inc.)] 2 parts Polyvinyl butyral (Eslec BM-S: manufactured by Sekisui Chemical) 0.2 part Tetrahydrofuran 50 parts And [Coating solution for charge transport layer] The following components were mixed and dissolved to prepare a coating solution for charge transport layer. 7 parts of charge transport material having the following structure

[0040]

Embedded image Polycarbonate 10 parts Methylene chloride 100 parts

Example 2 Coating solution 1 for intermediate layer and coating solution 2 for intermediate layer in Example 1
Was changed as follows, and an electrophotographic photosensitive member of Example 2 was obtained in exactly the same manner as in Example 1 except that an intermediate layer having a thickness of 4.5 μm was used. [Coating liquid 1 for intermediate layer] Titanium oxide powder [Taipeku CR-97 (manufactured by Ishihara Sangyo)] 60 parts Alkyd resin [Beccolite M6401-50 (manufactured by Dainippon Ink and Chemicals)] (solid content 50%) 12 parts Melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content: 60%) 7 parts Methyl ethyl ketone 1670 parts Cyclohexanone 621 parts The above components were mixed, ball milled, and the average of the above titanium oxide powder was obtained. The dispersion conditions were adjusted so that the particle diameter would be 0.65 μm, and the coating liquid for intermediate layer 1 was obtained. [Coating liquid 2 for intermediate layer] Titanium oxide powder [TTO-55 (A) (manufactured by Ishihara Sangyo)] 45 parts Alkyd resin [Beccolite M6003-60 (manufactured by Dainippon Ink and Chemicals)] (solid content 50%) 10 parts Melamine resin [Super Beckamine J-820-6 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content: 60%) 6 parts Methyl ethyl ketone 1372 parts Cyclohexanone 392 parts The dispersion conditions were adjusted so that the average particle diameter of the dispersion was 0.04 μm, to obtain a coating liquid 2 for an intermediate layer.

Example 3 Coating liquid 1 for intermediate layer and coating liquid 2 for intermediate layer in Example 1
Was changed as follows, and an electrophotographic photosensitive member of Example 3 was obtained in exactly the same manner as in Example 1 except that an intermediate layer having a thickness of 4.5 μm was used. [Coating liquid 1 for intermediate layer] Titanium oxide powder [Taipeku CR-55 (manufactured by Ishihara Sangyo)] 60 parts Alkyd resin [Beccolite M6401-50 (manufactured by Dainippon Ink and Chemicals)] (solid content 50%) 12 parts Melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink and Chemicals, Ltd.)] (solid content 60%) 7 parts Methyl ethyl ketone 1670 parts Cyclohexanone 615 parts The above components were mixed and ball milled, and the average of the above titanium oxide powder was obtained. The dispersion conditions were adjusted so that the particle diameter became 0.5 μm, and the coating liquid for an intermediate layer 1 was obtained. [Coating liquid 2 for intermediate layer] Titanium oxide powder [TTO-55 (C) (manufactured by Ishihara Sangyo)] 40 parts Alkyd resin [Beccolite M6003-50 (manufactured by Dainippon Ink and Chemicals)] (solid content 50%) 10 parts Melamine resin [Super Beckamine J-820-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content: 60%) 6 parts Methyl ethyl ketone 1375 parts Cyclohexanone 400 parts The dispersion conditions were adjusted so that the average particle size of the above was 0.25 μm, to obtain a coating liquid 2 for an intermediate layer.

Comparative Example 1 Coating Liquid 1 for Intermediate Layer and Coating Liquid 2 for Intermediate Layer in Example 1
The solvent type and amount added were changed as follows, and the prepared coating liquid was mixed and stirred to form a coating liquid for the intermediate layer, which was applied by a dip coating method, and dried to form a 4.5 μm-thick intermediate layer. An electrophotographic photoreceptor of Comparative Example 1 was obtained in exactly the same manner as in Example 1 except that [Coating Liquid 1 for Intermediate Layer] Titanium oxide powder [Taipeku CR-EL (Ishihara Sangyo)] 60 parts Alkyd resin [Beccolite M6401-50 (Dainippon Ink & Chemicals)] (Solid content 50%) 12 parts Melamine resin [Super Beckamine G-821-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content 60%) 7 parts Methyl ethyl ketone 70 parts The above components were mixed and ball milled, and the average particle size of the titanium oxide powder was reduced. The dispersion conditions were adjusted so as to be 0.5 μm, and thus a coating liquid 1 for an intermediate layer was obtained. [Coating liquid 2 for intermediate layer] Titanium oxide powder [TTO-55 (N) (manufactured by Ishihara Sangyo)] 50 parts Alkyd resin [Beccolite M6003-50 (manufactured by Dainippon Ink and Chemicals)] (solid content: 50%) 10 parts Melamine resin [Super Beckamine J-820-60 (manufactured by Dainippon Ink and Chemicals, Inc.)] (solid content 60%) 6 parts Methyl ethyl ketone 70 parts The above components are mixed and ball milled, and the average particles of the titanium oxide powder are obtained. The dispersion conditions were adjusted so that the diameter was 0.06 μm, and the coating liquid for an intermediate layer 2 was obtained. The above-mentioned intermediate layer coating liquid 1 and intermediate layer coating liquid 2 were mixed and stirred to obtain an intermediate layer coating liquid.

Comparative Example 2 Coating Liquid 1 for Intermediate Layer and Coating Liquid 2 for Intermediate Layer in Example 1
Was mixed and stirred to obtain one coating liquid for an intermediate layer, and applied and dried by a spray coating apparatus having one spray head to obtain an intermediate layer having a thickness of 4.5 μm. Similarly, an electrophotographic photosensitive member of Comparative Example 2 was obtained.

With respect to the electrophotographic photoreceptors of Examples 1 to 3 and Comparative Examples 1 and 2 thus produced, the coating surface of the intermediate layer was observed and visually evaluated at the time of coating the intermediate layer.

Next, after the formation of the photosensitive layer, a paper-passing test was carried out for each photosensitive member up to 40,000 sheets by a modified machine of an electrophotographic copying machine Imagio MF2200 (manufactured by Ricoh Co., Ltd.). The potential characteristics and image quality characteristics of the photoreceptor were evaluated at an early stage of the paper-passing test and after 40,000 sheets of the paper-passing test. Dark area potential: Surface potential of photoreceptor when moved to the developing section position after primary charging Light area potential: Image exposure (solid exposure) after primary charging
Photoreceptor surface potential at the time of moving to the developing section Image quality: Comprehensive evaluation of solid density, fine line reproducibility, local defects such as black spots, background stains, abnormal images, etc. Coating surface quality: ○… No problem △… Partial coating unevenness, defects X: Coating unevenness, defects present on entire surface Evaluation results are shown in Table 1.

[0047]

[Table 1]

As is clear from Table 1, the electrophotographic photoconductors of Examples 1 to 3 satisfying the claims of the present invention are:
It can be seen that the quality of the coating film is excellent, the reproducibility of the dark part potential and the light part potential is excellent in the actual machine characteristics, the deterioration of the electric characteristics is small, and a high-quality hard copy can be stably obtained for a long period of time. On the other hand, in the electrophotographic photoconductors of Comparative Examples 1 and 2, there is a problem with the coating film quality, and any one of the electrical characteristics and the image characteristics is greatly deteriorated in a short period, and the superiority of the photoconductor of the present invention is apparent. It is.

[0049]

As described above, according to the present invention, it is possible to obtain an electrophotographic photoreceptor excellent in photosensitivity characteristics, durability and image quality stability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an example of an electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 21: conductive support 23: photosensitive layer 25: intermediate layer 31: charge generation layer 33: charge transport layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor: Adult Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H068 AA44 CA29 EA17

Claims (2)

[Claims] 1. A method for producing an electrophotographic photoreceptor comprising an intermediate layer and a photosensitive layer sequentially formed on a conductive support, wherein said intermediate layer comprises two types of intermediate layers each containing an inorganic compound having a different average particle size. A method for producing an electrophotographic photoreceptor, wherein a coating film is formed simultaneously by two spray heads using a forming coating liquid. 2. The two types of coating liquids for forming an intermediate layer,
Also composed of inorganic compound and binder resin, for forming one intermediate layer
The average particle size of the inorganic compound contained in the coating solution is D ₁The other
The average particle size of the inorganic compound contained in the coating liquid for forming the intermediate layer
D_Two, Then D_Two/ D₁Satisfy the relationship of ≤ 1/5
The method for producing an electrophotographic photosensitive member according to claim 1, wherein
Law.