JP2002189305A - Apparatus for producing electrophotographic photoreceptor and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing electrophotographic photoreceptors in which all substrates can be simply and easily coated in a uniform film thickness by multiple dip coating and to provide a method for producing the photoreceptors. SOLUTION: In the apparatus for producing electrophotographic photoreceptors with a coating tank 4 filled with a coating liquid 5 in which a plurality of cylindrical electrically conductive substrates are simultaneously dipped, the coating tank 4 has a plurality of openings 12 into which the coating liquid 5 overflows when the cylindrical electrically conductive substrates are dipped in correspondence with the number of the substrates and also has a smaller number of coating liquid supply ports 14 than the number of the openings 12. The openings 12 are made lower in the vertical direction in accordance with the increase of the distance from the coating liquid supply ports 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor manufacturing apparatus and method for simultaneously producing a plurality of organic electrophotographic photoreceptors for use in image forming apparatuses such as copiers, printers and facsimiles by dip coating. It is.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member (hereinafter, also simply referred to as a "photosensitive member") is mounted on an image forming apparatus such as a copying machine or a laser beam printer employing an electrophotographic method. This photoreceptor is constituted by providing a photoconductive photosensitive layer on at least the surface of a cylindrical substrate having conductivity. The substrate is made of a non-magnetic metal such as aluminum, aluminum alloy, copper, brass and stainless steel. An image is formed on the surface of the photoconductor by performing processes such as charging, exposure, development, and transfer.

As a method for forming a photosensitive layer on the surface of a substrate, a coating method by vapor deposition, dipping, or spraying can be used. The coating method by immersion is a method in which a suspended substrate is immersed in a coating solution for forming a photosensitive layer and then pulled up at a predetermined speed. Because it can be easily adjusted by the viscosity and the pulling speed of the substrate, it is used more often than other methods. In the dip coating method, usually "multiple picking"
It is possible to immerse and pull up a plurality of substrates in a coating solution at the same time, and this method is excellent in mass productivity.

[0004] In the case of performing such simultaneous coating of a plurality of pieces,
Since there is a difference between the pressure and the flow velocity of the coating liquid depending on the location in the coating tank, there is a problem that a difference occurs in the coating film thickness. In order to avoid this, Japanese Utility Model Publication No. 4-27569 discloses:
The coating tank further has an independent coating tank for each substrate,
A method of supplying a coating liquid to each coating tank through independent supply pipes is described. It is described that by this method, a coating liquid flows at a substantially uniform flow rate to all positions of the immersed substrate, so that a uniform film thickness is applied to all the substrates.

In Japanese Patent Laid-Open No. 7-251114,
In order to solve the above-mentioned problem, it is described that a plurality of coating tanks are provided and a flow control valve is provided at a coating liquid supply port corresponding to each coating tank. It is described that a uniform amount of the coating liquid is supplied to all the substrates while the amount of the coating liquid supplied to each coating tank is kept constant by a flow rate control valve.

Further, in order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No. Hei 7-132258 discloses that a detachable part is attached to the upper end of the coating tank to make the flow of the coating liquid constant. . Since the upper end is pre-processed so that the coating liquid flows out at a constant flow rate, the flow of the coating liquid becomes constant only by attaching the upper end, and the coating with a uniform film thickness is performed on all the substrates. It is described.

[0007]

As described above, the method of supplying the coating liquid to each coating tank by independent supply pipes not only complicates the structure of the coating apparatus, but also increases the cost of the apparatus. In addition, there is a problem in that an extra coating liquid for each supply pipe is required for coating, and the production cost is increased. The method of providing the flow rate control valve has problems such as a change in the flow rate due to a change in the opening / closing state of the valve over time or the attachment of pigment or the like to the valve. The method of attaching the detachable component to the upper end of the coating tank requires the mounting components of the opening requiring extremely high precision by the number of the openings. In addition, it is necessary to prepare a set of parts having an optimum shape or size for each coating solution, which greatly increases the cost of the parts. Further, in order to replace a part, it is necessary to temporarily lower the liquid level to a position where the application liquid does not contact the part, which causes a problem that production efficiency is deteriorated.

[0008] In particular, in the coating solution for the charge transport layer,
Since the viscosity is much higher than that of other coating liquids for the undercoat layer and the charge generation layer, there is a difference in liquid pressure between the opening close to the coating liquid supply port and the opening far from the coating liquid supply port. Can not be obtained. For this reason, the thickness of the applied photoreceptor drum varies, which causes image unevenness in a copying machine or the like equipped with the drum.

In recent years, a halogen-based organic solvent generally used as a coating solution solvent used in a large amount for coating an organic electrophotographic photosensitive member has a large adverse effect on the global environment or a human body such as a worker. And non-halogen organic solvents are used. Non-halogenated organic solvents having relatively high solubility have lower volatility than halogenated organic solvents, and the upper end of the drum is easily sagged in photoconductor coating. If the solid content is increased to prevent sagging, the viscosity of the coating solution will be higher than that using a halogen-based organic solvent, and the variation in the thickness of the photosensitive drum coated with this coating solution will be greater. And image unevenness appears remarkably.

An object of the present invention is to provide a manufacturing apparatus and a manufacturing method of an electrophotographic photoreceptor capable of easily and easily coating all substrates with a uniform film thickness in a so-called multi-dip coating method. It is to be.

[0011]

The present invention relates to an electrophotographic photoreceptor manufacturing apparatus having a coating tank filled with a coating liquid and simultaneously immersing a plurality of cylindrical conductive substrates, wherein the coating tank comprises: A plurality of openings corresponding to the number of the cylindrical conductive substrates, which are openings through which the coating liquid overflows by immersing the cylindrical conductive substrates, and a number of coating liquid supply ports smaller than the openings. The opening is set vertically lower as the distance from the coating liquid supply port increases, and the opening is set to be lower in the electrophotographic photosensitive member.

According to the present invention, in a coating tank for dip coating a plurality of substrates, the coating liquid is placed at a lower position in the vertical direction as the distance from the coating liquid supply port increases, so that the coating liquid is , Uniform pressure and uniform flow rate and flow velocity. That is, if the position in the vertical direction is the same, since the flow rate and the flow velocity are lower at the opening farther from the coating liquid supply port and it is difficult to overflow, the opening is lower at a position farther from the coating liquid supply port and farther from the supply port. The flow rate and the flow rate of the coating liquid in the opening that is unlikely to overflow can be made equal to the flow rate and the flow rate in the opening close to the supply port. As a result, it is possible to apply the photoconductors without unevenness in the film thickness in the longitudinal direction, and it is also possible to simultaneously apply a plurality of substrates by dip coating with the same film thickness. A good image can be obtained from a copier or the like without density unevenness, and there is no variation in image quality due to the photoconductor.

Further, the present invention is characterized in that the vertical positional relationship between the plurality of cylindrical conductive substrates to be simultaneously applied by dip coating is set to be the same as the vertical positional relationship of the openings. I do.

According to the present invention, in the dip coating apparatus, which is the apparatus for manufacturing an electrophotographic photosensitive member, the cylindrical conductive substrate corresponding to each of the openings whose positions have been adjusted as described above may include:
Since it is fixed and gripped in the same positional relationship as the vertical position of the opening, even when the suspended cylindrical conductive substrate is lowered to any extent and immersed, The coating can be performed in the same manner without variation in the uncoated portion of the cylindrical conductive substrate. That is, the depth from the coating liquid surface immersed differs for each substrate,
The coating liquid where the substrate is immersed more deeply is applied with more pressure, and the flow of the coating liquid in the coating tank does not become uneven, and the film thickness of all the cylindrical conductive substrates is made equal. Can be formed.

Further, the present invention is characterized in that the coating tank has a mechanism capable of individually adjusting the position of each opening in the vertical direction.

According to the present invention, a mechanism capable of adjusting the vertical position of each opening, for example, a cylindrical portion having an opening is formed separately from the coating tank, and each of the coating tank and the overflow tank has a cylindrical shape. A mechanism in which two joints to be joined to a portion are attached, a thread is cut around the outer periphery of the cylindrical portion and the joint, and the height of the opening is adjusted by screwing the cylindrical portion to the joint. , So that the position of each opening is appropriately adjusted using the openings that require high precision as they are, so that the flow rate and flow rate of the coating liquid at each opening can be made equal in a short working time. Can be adjusted. In particular, when immersion is performed by changing the viscosity of the same coating solution with the same components, not only can the dip coating be performed in the same coating bath, but also the position can be easily adjusted without removing the coating solution from the coating bath for position adjustment. Can be adjusted.

By providing a stopper in the screw portion, it is possible to prevent the application liquid from entering the screw portion by adjusting the position.

Further, the present invention is characterized in that it has a mechanism capable of adjusting the position of each cylindrical conductive substrate so that the vertical positional relationship between the cylindrical conductive substrates can be changed.

According to the present invention, a mechanism capable of adjusting and changing the positional relationship between the cylindrical conductive substrates for each of the cylindrical conductive substrates, for example, the screw shaft portion X fixed to the substrate side. And a nut portion Y fixed to the elevator 2 side and screwed to the screw shaft portion X, and the length of the grip portion can be adjusted to an appropriate length in the vertical direction and fixed. Since the adjusting mechanism is provided, the adjusting mechanism can easily adjust the positional relationship between the cylindrical conductive substrates in accordance with the vertical positional relationship of the openings. It can be applied to a coating solution, and especially when immersed in a plurality of types of coating solutions sequentially, the production efficiency can be increased without removing the substrate.

Further, the present invention is characterized in that the coating liquid is a coating liquid for a charge transport layer of a laminated electrophotographic photosensitive member.

According to the present invention, since the coating solution for the charge transport layer is used in the dip coating device, which is the device for manufacturing the electrophotographic photosensitive member, a charge having a particularly high viscosity is used in the coating solution for the laminated electrophotographic photosensitive member. Even with the transport layer coating liquid, a uniform flow rate and flow rate can be obtained in the coating tank. As a result, it is possible to apply the photoconductors without unevenness in the film thickness in the longitudinal direction, and it is also possible to simultaneously apply a plurality of substrates by dip coating with the same film thickness. A good image can be obtained from a copier or the like without density unevenness, and there is no variation in image quality due to the photoconductor.

The present invention is also characterized in that the coating solution for the charge transport layer is a coating solution containing a non-halogen solvent.

According to the present invention, the dip coating apparatus, which is the apparatus for manufacturing the electrophotographic photosensitive member, uses a coating solution using a non-halogen solvent, and therefore has a higher global environmental and environmental impact than a halogen-based solvent, especially a chlorine-based solvent. Uniform flow rate and flow rate can be obtained in the coating tank even for coating liquids that have low adverse effects on human bodies such as workers and have higher solids and higher viscosity than coating liquids that use halogenated solvents. Can be This makes it possible to apply the photoconductors without unevenness in the film thickness in the longitudinal direction, and simultaneously apply a plurality of substrates by dip coating at the same film thickness. A good image without density unevenness can be obtained from a mounted copying machine or the like, and there is no variation in image quality due to the photoconductor.

The present invention is also characterized in that the charge transport layer coating liquid has a viscosity of 250 mP · s or more at 25 ° C.

According to the present invention, a coating liquid having a viscosity at 25 ° C. of 250 mP · s or more is used in the dip coating apparatus which is the apparatus for manufacturing the electrophotographic photosensitive member. However, a uniform flow rate and flow rate can be obtained in the coating tank. In this way, the photoconductors can be applied without unevenness in the film thickness in the longitudinal direction, and at the same time, a plurality of substrates that have been dip-coated can be applied with the same film thickness. A good image can be obtained without density unevenness from a copying machine or the like, and there is no variation in image quality due to the photoconductor.

The present invention also relates to a method for producing an electrophotographic photosensitive member, wherein a plurality of cylindrical conductive substrates are simultaneously immersed in a coating tank filled with a coating solution to form a layer of the electrophotographic photosensitive member. In the coating tank, a plurality of openings corresponding to the number of the cylindrical conductive substrate, the opening in which the coating liquid overflows by immersing the cylindrical conductive substrate, and a coating liquid supply port smaller in number than the opening The openings are arranged vertically lower as the distance from the coating liquid supply port increases, and each cylindrical conductive substrate is immersed in the coating liquid in the coating tank from the corresponding opening. Features.

According to the present invention, in the method of dip coating a plurality of substrates, a coating tank having an opening vertically lower at a position farther from the coating liquid supply port is used, so that the coating liquid is formed at each opening. Has a uniform pressure and a uniform flow rate and flow velocity. That is, if the position in the vertical direction is the same, since the flow rate and the flow velocity are lower at the opening farther from the coating liquid supply port and it is difficult to overflow, the opening is lower at a position farther from the coating liquid supply port and farther from the supply port. The flow rate and the flow rate of the coating liquid in the opening that is unlikely to overflow can be made equal to the flow rate and the flow rate in the opening close to the supply port. As a result, it is possible to apply the photoconductors without unevenness in the film thickness in the longitudinal direction, and it is also possible to simultaneously apply a plurality of substrates by dip coating with the same film thickness. A good image can be obtained from a copier or the like without density unevenness, and there is no variation in image quality due to the photoconductor.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an electrophotographic photosensitive member according to the present invention is a method for producing an organic electrophotographic photosensitive member by so-called multi-drawing in a dip coating method. The organic electrophotographic photoreceptor is configured as a laminated or single-layer type photoreceptor using a general photoreceptor material. First, the materials and constitutions will be described, but the materials and constitutions of the organic electrophotographic photoreceptor in the present invention are not limited to the contents described below.

As the substrate, those having conductivity, for example, metals and alloy materials such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold and platinum can be used. it can. In addition, use of polyester film, paper or metal film, plastic or paper containing conductive particles, plastic containing conductive polymer, etc. on which aluminum, aluminum alloy, tin oxide, gold, indium oxide, etc. are deposited or coated. Can be. These materials are used after being processed into a cylindrical shape, a cylindrical shape, or a thin film sheet shape. Particularly, since the conductive substrate used in the present invention is applied by a dip coating method, the conductive substrate is preferably cylindrical.

A photosensitive layer is formed on the substrate. In the formation of the photosensitive layer, the cylindrical conductive substrate is coated with scratches and irregularities, the charging property is prevented from deteriorating during repeated use, and the charging characteristics in a low-temperature / low-humidity environment are improved. An undercoat layer may be provided between the substrate and the charge generation layer (CGL) / charge transport layer (CTL).

As the material of the undercoat layer, polyamide, copolymer nylon, polyvinyl alcohol, polyurethane, polyester, epoxy resin, phenol resin, casein, cellulose and gelatin have been known. Is often used. These resins can be prepared by mixing water and various organic solvents, especially water, a single solvent of methanol, ethanol or butanol, a mixed solvent of water and alcohols, or a mixed solvent of two or more alcohols, and a mixed solvent of acetone and dioxolane and alcohols. Or dichloroethane,
It is dissolved in a mixed solvent of a chlorine-based solvent such as chloroform and trichloroethane and an alcohol to prepare a coating solution for an undercoat layer.

The coating solution for the undercoat layer may contain zinc oxide or oxidized oxide, if necessary, particularly for the purpose of adjusting the volume resistivity of the undercoat layer and improving the repeated aging characteristics in a low-temperature / low-humidity environment. It is known that inorganic pigments such as titanium, tin oxide, indium oxide, silica and antimony oxide are dispersed and contained using a disperser such as a ball mill, a dyno mill and an ultrasonic oscillator.

The undercoat layer coating solution thus prepared is
The coating is performed on the surface of the cylindrical conductive substrate using a dip coating device described later. The proportion of the inorganic pigment in the undercoat layer is from 30 to
It is preferably in the range of 95% by weight, and the film is applied so that the film thickness is about 0.1 to 5 μm.

A photosensitive layer is formed on the substrate or, if the undercoat layer is provided on the substrate, on the undercoat layer.
In the case of a laminated photoreceptor, the photosensitive layer is a charge generation layer (CG).
L) and a charge transport layer (CTL) are laminated, and in the case of a single-layer type photoreceptor, it is configured as a single-layer photosensitive layer. Hereinafter, the laminated photoreceptor and the single-layered photoreceptor will be described separately.

In the case of a laminated photoreceptor, the charge generation layer (CG)
L) is a charge-generating substance (C
GM) as a main component, and if necessary, a known binder resin, a plasticizer, and a sensitizer. Charge generation material (CGM)
Examples thereof include perylene-based pigments such as peryleneimide and perylene anhydride, polycyclic quinone-based pigments such as quinacridone and anthraquinone, phthalocyanine-based pigments such as metal- or metal-free phthalocyanine, and halogenated metal-free phthalocyanine, squarium dyes, and azulhenium dyes , A thiapyrylium dye, and a carbazole skeleton, a styrylstilbene skeleton, a triphenylamine skeleton, a dibenzothiophene skeleton, an oxadiazole skeleton,
Examples include an azo pigment having a fluorenone skeleton, a bistilbene skeleton, a distyryloxadiazole skeleton or a distyrylcarbazole skeleton. Pigments having particularly high charge generating ability include metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, and gallium (chloro)
Examples include phthalocyanine pigments, mixed crystals of metal phthalocyanine and non-metal phthalocyanine, bisazo pigments containing a fluorene ring or a fluorenone ring, bisazo pigments composed of an aromatic amine, and trisazo pigments. When these pigments are contained, a photoconductor having high sensitivity can be provided.

As the binder resin, melamine resin, epoxy resin, silicone resin, polyurethane resin, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, vinyl chloride-acetic acid Vinyl-polyvinyl alcohol copolymer resin, polycarbonate resin, phenoxy resin, phenol resin,
Examples include polyvinyl butyral resin, polyarylate resin, polyamide resin, and polyester resin. Solvents for dissolving these resins include ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane, dioxolan and dimethoxyethane, benzene, toluene and xylene. Aprotic polar solvents such as aromatic hydrocarbons, N, N-dimethylformamide and dimethylsulfoxide can be used.

The charge generation layer (CGL) can be formed by a method of forming a compound directly by vacuum evaporation or by applying a coating liquid in which a charge generation substance (CGM) is dispersed in a binder resin solution. There is a way to do that. Generally, the latter method is preferable, and the present invention also uses the latter method. The method for mixing and dispersing the charge generating substance (CGM) in the binder resin solution and the method for applying the same are the same as those for the undercoat layer.
The ratio of the charge generation material (CGM) in the charge generation layer is 30
The range is preferably 90 to 90% by weight. Charge generation layer (CGL)
Is preferably 0.05 to 5 μm, more preferably 0.1 to 2.5 μm.

The charge transport layer (CTL) provided on the charge generation layer (CGL) includes a charge transport material (CTM) capable of receiving and transporting charges generated by the charge generation material (CGM), and It contains a binder resin and, if necessary, a known plasticizer and a sensitizer. Examples of the charge transport material (CTM) include an electron donating substance and an electron accepting substance. Examples of the electron donating substance include poly-N-vinylcarbazole and derivatives thereof,
γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensation product and derivatives thereof,
Polyvinylpyrene, polyvinylphenanthrene, oxazole derivative, oxadiazole derivative, imidazole derivative, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl)
Propane, styryl anthracene, styryl pyrazoline, pyrazoline derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine compounds, triphenylmethane compounds, stilbene compounds, and 3
And azine compounds having a methyl-2-benzothiazoline ring. Examples of the electron acceptor include fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyanoethylene, tetracyanoethylene Quinodimethane, promanyl, chloranil, benzoquinone and the like.

The binder resin constituting the charge transport layer (CTL) may be any resin that is compatible with the charge transport material (CTM). Examples thereof include polycarbonate and copolymerized polycarbonate, polyarylate, polyvinyl butyral, and polyamide. , Polyester, epoxy resin,
Examples include polyurethane, polyketone, polyvinyl ketone, polystyrene, polyacrylamide, phenolic resin, phenoxy resin and polysulfone resin, and copolymer resins thereof. These resins may be used alone or in combination of two or more. Among them, polystyrene,
Resins such as polycarbonate, copolycarbonate, polyarylate, and polyester have a volume resistivity of 10 ¹³ Ω or more and are excellent in film-forming properties and potential characteristics. Solvents that dissolve these materials include alcohols such as methanol and ethanol,
Ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethers such as ethyl ether, tetrahydrofuran, dioxane and dioxolane;
Aliphatic halogenated hydrocarbons such as chloroform, dichloromethane and dichloroethane, and aromatics such as benzene, chlorobenzene and toluene can be used.

The charge transport layer (CTL) is formed using a charge transport layer coating solution prepared by dissolving a charge transport material (CTM) in a binder resin solution. . The proportion of the charge transport material (CTM) in the charge transport layer is
A range of 30 to 80% by weight is preferred. Charge transport layer (CT
The film thickness of L) is preferably from 10 to 50 μm, more preferably from 15 to 40 μm.

Further, the photosensitive layer may contain one or more kinds of electron accepting substances or dyes to improve the sensitivity and suppress the increase of the residual potential and the fatigue upon repeated use. Examples of the electron acceptor include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride and 4-chloronaphthalic anhydride; cyano compounds such as tetracyanoethylene and terephthalmalondinitrile; 4-nitrobenzaldehyde; Aldehydes, anthraquinones such as anthraquinone and 1-nitroanthraquinone, and polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitrofluorenone; These can be used as chemical sensitizers.

Examples of the dye include organic photoconductive compounds such as xanthene dye, thiazine dye, triphenylmethane dye, quinoline pigment and copper phthalocyanine, and these can be used as an optical sensitizer.

Further, the photosensitive layer may contain a known plasticizer to improve moldability, flexibility and mechanical strength. Examples of the plasticizer include dibasic acid esters, fatty acid esters, phosphoric acid esters, phthalic acid esters, chlorinated paraffins, and epoxy-type plasticizers. In addition, the photosensitive layer, if necessary, a leveling agent for preventing orange peel such as polysiloxane, an antioxidant such as a phenol compound, a hydroquinone compound, a tocopherol compound and an amine compound for improving durability, Further, an ultraviolet absorber or the like may be contained.

In the case of a single-layer type photoreceptor, the same material as in the case of the multi-layer type photoreceptor is used, and the above-mentioned CGM is contained in the above-mentioned binder resin.
Is dispersed or CGM is dispersed in the form of pigment particles in the photosensitive layer containing the above-mentioned CTM to form a single photosensitive layer. The single-layer type photoreceptor has the advantage of being a photoreceptor for a positively charged image forming apparatus that generates less ozone, and has a single photosensitive layer to be applied, so that the manufacturing cost and the yield are lower than those of a multilayer type. There is also a point that can be.

In any of the above-described photoreceptor formulations and layer configurations, the coating solution for each layer is used in a manufacturing apparatus represented by a dip coating apparatus, and the respective layers are formed to produce a photoreceptor. . The solvent used in the above-mentioned coating solution for each layer is not limited to the above range, but the use of a non-chlorine (halogen) organic solvent is considered in consideration of the global environment and safety of workers. It is preferable in doing.

FIG. 1 is a schematic diagram showing a dip coating apparatus as an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention. The dip coating apparatus includes an elevator 2 for vertically moving a cylindrical conductive substrate 1 gripped by a gripper 11, a motor 3 as a driving source thereof, and a coating liquid 5 to be coated on the surface of the cylindrical conductive substrate 1. The stored coating tank 4, an overflow tank 13 for receiving the coating liquid 5 overflowed in the coating tank 4, a storage tank 7 for storing the coating liquid 5 from the overflow tank 13, and a coating tank 4 for storing the coating liquid 5 stored in the storage tank 7. , A stirrer 8 provided in a storage tank 7, an additional solvent tank 9, and a viscosity measurement and solvent addition device 10.

As the coating liquid 5 is consumed in the coating tank 4, the coating liquid 5 stored in the collection tank 7 is
Is supplied from the coating liquid supply port 14 to the coating tank 4 through the coating liquid supply port.
Further, the coating liquid 5 overflowing in the coating tank 4 is
It is returned from the recovery port 15 of the overflow tank 13 to the storage tank 7. The coating liquid 5 returned to the storage tank 7 is stirred by the stirrer 8, the viscosity is monitored by the viscosity measurement and solvent addition device 10, and the additional solvent is supplied from the additional solvent tank 9 so as to maintain a uniform viscosity. In the coating tank 7, a uniform viscosity is always maintained. The elevator 2 is driven by the rotation of the motor 3, and moves the cylindrical conductive substrate 1 fixed to the gripper 11 up and down at a predetermined speed to move the coating layer 4.
Immersed in the coating solution 5 inside. In particular, when a pigment dispersion coating liquid is used in the dip coating apparatus, a coating liquid dispersion apparatus typified by an ultrasonic generator (not shown) may be provided to stabilize the dispersibility of the coating liquid 5.

The dip coating apparatus, which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention, is a multi-punch type apparatus. In FIG. 1, the dip coating apparatus is used to facilitate the description of its configuration. , One cylindrical conductive substrate 1 is immersed. That is, in the multi-cavity type apparatus, the cylindrical conductive substrate 1 and the holding portion 11 should be configured to correspond to a plurality of substrates, but in FIG. 1, they are configured to correspond to a single substrate. Indicated.

FIG. 2 is a cross-sectional view schematically showing a first configuration example of the coating tank 4 in the dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention. FIG. 3 is a diagram showing a configuration of the application tank 4 in FIG. 2 as viewed from above. Therefore, FIG. 2 shows an AA cross section in FIG. The dip coating device is a multi-dip type dip coating device,
The configuration is the same as that shown in FIG. 1 except that the cylindrical conductive substrate 1, the coating tank 4, the gripper 11, and the overflow tank 13 are used for a multi-cavity method. As shown in FIGS. 2 and 3, the coating tank 4 has four openings 12 a to 12 d for immersing four substrates in the coating tank 4. As the four openings 12a to 12d are arranged farther from the application liquid supply port 14, the height position of the opening 12 is
It is set lower in the direction perpendicular to the coating liquid surface. Specifically, the opening 12a closest to the application liquid supply port 14 is
The opening 12 d which is the highest and is farthest from the application liquid supply port 14
Is set the lowest. Opening 12a and Opening 1
2c and the opening 12b and the opening 12d at the same distance from the application liquid supply port 14, the opening 12a
And an opening 12c at an intermediate height position and at the same height position.

The flow rate of the coating liquid 5 in the coating tank 4 is faster at an opening close to the coating liquid supply port 14 than at an opening far from the coating liquid supply port 14 if the opening is at the same height in the vertical direction of the coating liquid surface. . Therefore, the coating liquid hardly overflows at the opening far from the coating liquid supply port 14 than at the opening close thereto. FIG.
As shown in, by lowering the position of the opening as it is farther from the coating liquid supply port, the coating liquid has the same pressure at each opening, and the coating liquid easily overflows even at the opening far from the supply port. In addition, the flow rate and the flow rate of the coating liquid in the coating tank can be made uniform. By making the flow rate and flow velocity of the coating liquid in the coating tank uniform, it is possible to apply the coating to each substrate immersed from each opening without unevenness in the film thickness in the longitudinal direction, and to apply to any substrate. The coating liquid is applied equally, and a film is formed with the same thickness. A good image can be obtained from a copying machine or the like equipped with these photoconductors without density unevenness, and there is no variation in image quality due to the photoconductors.

If dip coating is performed by such a dip coating apparatus, a coating liquid for a charge transport layer having a high viscosity of 250 mP · s or more at 25 ° C., for example, a coating liquid having an increased viscosity with the use of a halogen-based solvent is used. It is particularly effective in such cases.

FIG. 4 is a cross-sectional view schematically showing a part of a second configuration example of the coating tank 4 in the dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention. The dip coating apparatus is the same as that of FIG. 2 except for the configuration of the cylindrical portion 20 having the opening 12 in the coating tank 4. That is, FIG.
In the entire coating tank 4, the number of the openings 12 is four,
The arrangement is also the same as in FIGS. As shown in FIG. 4, the cylindrical portion 20 having the opening 12 in the coating tank 4 is configured separately from the coating tank 4. Joining portions 16 and 17 to be joined to the cylindrical portion 20 are attached to the coating tank 4 and the overflow tank 13, respectively. The outer circumference of the cylindrical portion 20 and the joints 16 and 17 are threaded, and the cylindrical portions 2 and
0 is screwed and connected. Therefore, the cylindrical portion 20
Is rotated, the cylindrical portion 20 is moved in the vertical direction indicated by the arrow 21, and the height position of the opening 12a can be adjusted and fixed. At the time of position adjustment, stoppers 18 and 19 are respectively provided at the joints 16 and 17 so that the coating liquid does not enter into a portion where the cylindrical portion and the joints 16 and 17 come into contact with each other. There is no leakage to the part other than 4 and the overflow tank 13.

With such a mechanism, the position of each of the four openings 12 of the coating tank 4 is appropriately adjusted, so that the openings requiring high accuracy can be used as they are. By adjusting the position appropriately, it is possible to adjust the flow rate and the flow rate of the coating liquid in each opening 12 to be equal to each other in a short working time, similarly to the opening 12 shown in FIG. In particular, when immersion is performed while changing the viscosity of the same coating solution with the same components, not only can the immersion coating be performed in the same coating bath 4, but also the coating solution can be easily removed without removing the coating solution from the coating bath 4 for position adjustment. The position can be adjusted.

FIG. 5 is a diagram schematically showing an example of the configuration of the gripper 11 in the dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention. FIG. 6 shows the gripper 11b of FIG.
It is sectional drawing which expands and shows the structural example of FIG. The grip 11
Are provided corresponding to the openings 12 of the coating tank 4 shown in FIG. That is, the holding parts 11a, 11b and 1
1c is arranged in the horizontal direction of the coating liquid surface so that it can be immersed in the coating liquid in the coating tank 4 from the openings 12a, 12b and 12c, respectively. The grips 11a, 11b, and 11c are respectively provided with openings 12a, 12b, and 12c.
It is provided so as to be adjustable in accordance with the positional relationship in the vertical direction of the coating liquid surface of c. Specifically, each grip 11
The length can be adjusted to an appropriate length in the vertical direction of the coating liquid surface and fixed. For example, as shown in FIG.
b comprises a screw shaft portion X fixed to the base body side and a nut portion Y fixed to the elevator 2 side and screwed with the screw shaft portion X. With this mechanism, the length of the grip portion 11b can be appropriately adjusted and fixed.

As shown in FIG. 2, when the holding portion 11 is provided so as to correspond to the coating tank 4 in which the height of each opening 12 is fixed, the length is always adjustable. It may not be necessary, and may be fixed to a length corresponding to each opening 12 in advance.

By appropriately adjusting the length of each of the gripping portions 11, the hanging position of each cylindrical conductive substrate 1 can be adjusted.
It can be adjusted and fixed according to the corresponding opening 12. Thereby, at the time of dip coating, each cylindrical conductive substrate 1 can be immersed in the coating tank 4 at the same depth at the same time, so that the film thickness can be made equal. For example, each substrate has a different depth from the surface of the coating liquid immersed, and the coating liquid where the substrate is further immersed is more pressed, and the flow of the coating liquid in the coating tank becomes uneven. Without this, the thickness of all the cylindrical conductive substrates can be formed to be equal. In addition, since the positional relationship between the cylindrical conductive substrates can be easily adjusted according to the positional relationship between the openings in the direction perpendicular to the coating liquid surface, it can be used for a large number of coating liquids. It is possible, especially when sequentially immersing in multiple types of coating solutions,
Production efficiency can be increased without removing the base.

FIG. 7 is a cross-sectional view schematically showing a third configuration example of the coating tank 4 in the dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention. The dip coating device,
The configuration is the same as that of FIG. 2 except that the height positions of the openings 12a, 12b, and 12c are set equally in the direction perpendicular to the surface of the coating liquid, and the adjuster 22 is provided. The adjuster 22 can adjust the position of the application liquid supply port 14 in the vertical direction.

By adjusting the position of the application liquid supply port 14 in the vertical direction by the adjusting device 22, the flow of the application liquid in the application tank 4 can be adjusted to be uniform. The thickness of each immersed cylindrical conductive substrate 1 can be made equal.

As shown in FIG. 2, the adjusting device 22 is used in the coating tank 4 which is adjusted in advance so that the height positions of the openings 12 are different, and the flow of the coating liquid becomes uniform. Fine adjustment may be made as described above.

After each layer of the photoreceptor is sequentially coated and formed by each of the various dip coating apparatuses as described above, or each time each layer is coated and formed, the substrate on which the layer is formed is dried by a dryer such as hot air or far infrared rays. To complete the formation of the photoreceptor layer. Drying is preferably performed at 40 ° C. to 130 ° C. for about 10 minutes to 2 hours.

Hereinafter, an apparatus and a method for manufacturing an electrophotographic photosensitive member according to the present invention will be described in detail with reference to the accompanying drawings by way of examples.

FIG. 8 shows a coating tank 4 and a gripper 11 in a dip coating apparatus which is a conventional apparatus for manufacturing an electrophotographic photosensitive member.
FIG. 2 is a cross-sectional view schematically showing a configuration example of FIG. The configuration of the application tank 4 in FIG. 8 as viewed from above is the same as that in FIG. Therefore, FIG. 8 shows an AA cross section in FIG.
This dip coating apparatus is a multi-dip type dip coating apparatus, and has the configuration shown in FIG. 1 except that the cylindrical conductive substrate 1, the coating tank 4, the gripper 11, and the overflow tank 13 are used for the multi-dip method. Is the same as As shown in FIGS. 3 and 8, the coating tank 4 has four openings 12 a to 12 d for dipping four substrates in the coating tank 4, and has four openings 12 a to 12 d. The height position is set equally in the vertical direction of the coating liquid surface.

Example 1 A mixture of 28.7 parts by weight of methyl alcohol and 53.3 parts by weight of 1,2-dichloroethane was mixed with rutile-type titanium oxide (TTO-Ishihara Sangyo Co., Ltd.).
M-1) A mixture of 17.1 parts by weight and 0.9 parts by weight of a copolymerized nylon resin (CM8000, manufactured by Toray Industries, Inc.) as a binder resin was dispersed for 8 hours with a paint shaker, and the coating liquid for an undercoat layer was dispersed. Prepared. Then, the prepared coating solution for the undercoat layer was filled in the coating tank of the dip coating apparatus shown in FIG. 8, and four aluminum cylindrical conductive substrates having a diameter of 65 mmφ and a length of 348 mm were immersed in the coating tank and dried. An undercoat layer was formed so that the thickness of the undercoat layer was about 0.9 μm.

Next, 1.5 parts by weight of a bisazo pigment (chlorodiane blue) represented by the following structural formula (I), 1.5 parts by weight of butyral resin (XYGS, manufactured by Union Carbide Co.), and 97 parts by weight of methyl isobutyl ketone The mixture was dispersed for 10 hours with a paint shaker to prepare a coating solution for a charge generation layer. Next, the prepared coating solution for the charge generation layer was filled in the coating bath of the dip coating device shown in FIG.
Four cylindrical conductive substrates provided with an undercoat layer were immersed in the coating tank to form a charge generation layer (CGL) such that the film thickness after drying was about 0.9 μm.

[0065]

Embedded image

Next, 10 parts by weight of a hydrazone-based charge transporting substance (4-diethylaminobenzaldehyde-N, N-diphenylhydrazone) represented by the following structural formula (II) and a bisphenol Z type polycarbonate resin (manufactured by Mitsubishi Gas Chemical Company, Ltd.) Z-400) 10 parts by weight and a silicone leveling agent (KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.)
And 02 parts by weight were added to 80 parts by weight of dichloromethane and completely dissolved to prepare a coating solution for a charge transport layer. The coating liquid had a solid content of 23% by weight, a liquid temperature of 25 ° C., and a viscosity of 170 mPa.
-It was s. The prepared coating solution for the charge transport layer is filled in a coating tank of a dip coating apparatus shown in FIG. 7, and a cylindrical conductive substrate provided with a charge generation layer (CGL) is immersed in the coating tank to form a dried film. A charge transport layer (CTL) was formed so as to have a thickness of 20 μm, and four laminated electrophotographic photosensitive members were produced.

[0067]

Embedded image

At the time of forming the undercoat layer, in the coating tank of the dip coating apparatus shown in FIG. 8, the opening 12 shown in FIG.
Each of the substrates immersed from a, 12b, 12c, and 12d has the openings 12a, 12b, and 1 arranged similarly when the charge generation layer and the charge transport layer are formed.
Dipped from 2c and 12d. In forming the charge transport layer, the position of the coating liquid supply port in the coating tank of the dip coating apparatus shown in FIG. 7 is adjusted in the vertical direction to adjust the flow of the coating liquid in the coating tank to be uniform. did.

Comparative Example 1 Using the same undercoat layer coating solution, charge generation layer coating solution and charge transport layer coating solution as in Example 1, not only the undercoat layer and the charge generation layer but also the charge transport With respect to the layers, an undercoat layer, a charge generation layer and a charge transport layer were formed in the same manner as in Example 1 by the dip coating apparatus shown in FIG. 8, and four laminated electrophotographic photosensitive members were produced.

Example 2 Methyl alcohol 80.75
Parts by weight of a mixed solvent of 4.25 parts by weight of methyl propylene glycol and rutile-type titanium oxide (T.I.
A mixture of 10 parts by weight of TO-M-1) and 5 parts by weight of a copolymerized nylon resin (CM8000, manufactured by Toray Industries, Inc.) as a binder resin was dispersed for 8 hours with a paint shaker to prepare a coating solution for an undercoat layer. . Next, the prepared undercoat layer coating solution was filled in the coating tank of the dip coating device shown in FIG.
Four aluminum cylindrical conductive substrates having a diameter of 65 mmφ and a length of 348 mm were immersed in the coating tank, and an undercoat layer was formed so that the film thickness after drying was about 0.9 µm.

Next, 1.5 parts by weight of the bisazo pigment (chlorodiane blue) represented by the structural formula (I), 1.5 parts by weight of butyral resin (XYGS manufactured by Union Carbide Co.), and 97 parts by weight of methyl isobutyl ketone The mixture was dispersed for 10 hours with a paint shaker to prepare a coating solution for a charge generation layer. Next, the prepared coating solution for the charge generation layer was filled in the coating bath of the dip coating device shown in FIG.
Four cylindrical conductive substrates provided with an undercoat layer were immersed in the coating tank to form a charge generation layer (CGL) such that the film thickness after drying was about 0.9 μm.

Next, 12 parts by weight of a hydrazone-based charge transporting substance (4-diethylaminobenzaldehyde-N, N-diphenylhydrazone) represented by the structural formula (II) and a bisphenol Z type polycarbonate resin (manufactured by Mitsubishi Gas Chemical Company, Ltd.) Z-400) 12 parts by weight and a silicone-based leveling agent (KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.)
02 parts by weight were added to 76 parts by weight of tetrahydrofuran, heated at 45 ° C. and completely dissolved, and then naturally cooled to prepare a charge transport layer coating solution. The coating solution had a solid content of 23.
% By weight, liquid temperature 25 ° C., viscosity 250 mPa · s.
The prepared coating solution for the charge transport layer is filled in the coating tank of the dip coating apparatus shown in FIG. 4, and the charge generating layer (CGL) is filled in the coating tank.
5 is immersed using the gripping portion shown in FIG. 5 to form a charge transport layer (CTL) so that the film thickness after drying is 20 μm. A photoreceptor was prepared.

At the time of forming the undercoat layer, in the coating tank of the dip coating apparatus shown in FIG. 8, the opening 12 shown in FIG.
Each of the substrates immersed from a, 12b, 12c, and 12d has the openings 12a, 12b, and 1 arranged similarly when the charge generation layer and the charge transport layer are formed.
Dipped from 2c and 12d. In forming the charge transport layer, the height position of each opening in the coating tank of the dip coating apparatus shown in FIG. 4 is adjusted, and the length of the gripping part of the dip coating apparatus shown in FIG. By adjusting the height in accordance with the height of the opening, the flow of the coating liquid in the coating tank was adjusted to be uniform.

COMPARATIVE EXAMPLE 2 Using the same undercoat layer coating solution, charge generation layer coating solution and charge transport layer coating solution as in Example 2, not only the undercoat layer and the charge generation layer but also the charge transport With respect to the layers, an undercoat layer, a charge generation layer and a charge transport layer were formed in the same manner as in Example 2 using the dip coating apparatus shown in FIG. 8, and four laminated electrophotographic photosensitive members were produced.

(Evaluation) Examples 1 and 2, Comparative Examples 1 and 2
The thickness of the charge transport layer (CTL) was measured for each of the four electrophotographic photoreceptors manufactured in the above. Further, these photoconductors were mounted on a copying machine (SF-2030 manufactured by Sharp Corporation), and image inspection and electrical characteristics were confirmed.

In the first embodiment, the openings 12a, 12b, 12
It was found that in the four photoconductors prepared by immersion coating from c and 12d, the CTL film was uniformly applied with a variation within 1 μm without unevenness. In all of these photosensitive drums, there was no problem in terms of image and electrical characteristics. The non-defective rate when 98 photosensitive drums were manufactured under the conditions of Example 1 was 98%.

In Comparative Example 1, the openings 12a, 12b, 12
In the four photoconductors prepared by dip coating from c and 12d, the CTL film has an opening 1 far from the coating liquid supply port.
It was found that the three photosensitive drums dipped from 2d, 12b and 12c were applied unevenly with a variation of 3 μm. For these three photosensitive drums,
Density unevenness occurred in the halftone image in the longitudinal direction of the drum. The non-defective rate in the case of producing 100 photosensitive drums under the conditions of Comparative Example 1 was 80%.

In the second embodiment, the openings 12a, 12b, 12
It was found that, in the four photoconductors prepared by dip coating from c and 12d, the CTL films were uniformly coated with a variation within 0.5 μm without unevenness. In all of these photosensitive drums, there was no problem in terms of image and electrical characteristics. The non-defective rate in the case of producing 100 photosensitive drums under the conditions of Example 2 was 98%.

In Comparative Example 2, the openings 12a, 12b, 12
In the four photoconductors prepared by dip coating from c and 12d, the CTL film has an opening 1 far from the coating liquid supply port.
It was found that the three photosensitive drums dipped from 2d, 12b and 12c were applied unevenly with a variation of 5 μm. For these three photosensitive drums,
Density unevenness occurred in the halftone image in the longitudinal direction of the drum. The non-defective rate when 100 photosensitive drums were manufactured under the conditions of Comparative Example 2 was 50%.

In the present example and the comparative example, the experiment was conducted in a four-coating coating tank, but the electrophotography according to the present invention was applied to a multi-coating apparatus for coating a larger number of 16 or more coats. Greater effects can be expected by using the coating method, which is a method for manufacturing a photoconductor, and the coating apparatus, which is an apparatus for manufacturing an electrophotographic photoconductor according to the present invention.

[0081]

According to the present invention, in a coating tank for dip coating a plurality of substrates, the farther from the coating liquid supply port, the lower the opening is in the vertical direction, so that coating is performed at each opening. The liquid has a uniform pressure, a uniform flow rate and a uniform flow rate, and can be applied to each photoreceptor without unevenness in the film thickness in the longitudinal direction. Therefore, it is possible to provide a manufacturing apparatus and a manufacturing method of an electrophotographic photoreceptor that can obtain a good image without density unevenness and that does not cause a variation in image quality due to the photoreceptor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a first configuration example of a coating tank 4 in a dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention.

FIG. 3 is a diagram showing a configuration of a coating tank 4 in FIG. 2 as viewed from above.

FIG. 4 is a cross-sectional view schematically showing a part of a second configuration example of the coating tank 4 in the dip coating apparatus which is the apparatus for manufacturing an electrophotographic photosensitive member according to the present invention.

FIG. 5 is a diagram schematically illustrating a configuration example of a gripping unit 11 in a dip coating apparatus which is an apparatus for manufacturing an electrophotographic photosensitive member according to the present invention.

FIG. 6 is a cross-sectional view showing, on an enlarged scale, an example of the structure of a gripper 11b shown in FIG.

FIG. 7 is a cross-sectional view schematically illustrating a third configuration example of the coating tank 4 in the dip coating apparatus which is the apparatus for manufacturing an electrophotographic photosensitive member according to the present invention.

FIG. 8 is a cross-sectional view schematically illustrating a configuration example of a coating tank 4 and a gripper 11 in a dip coating apparatus which is a conventional apparatus for manufacturing an electrophotographic photosensitive member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical conductive base 2 Elevator 3 Motor 4 Coating tank 5 Coating liquid 6 Pump 7 Storage tank 8 Stirrer 9 Additional solvent tank 10 Viscosity measurement and solvent addition apparatus 11 Grasping part 12a, 12b, 12c, 12d Opening 13 Overflow tank 14 Coating liquid supply port 15 Collection port

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masanori Matsumoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H068 AA35 BA01 BA11 EA14 EA16 EA20 4D075 AB02 AB04 AB12 AB36 AB54 CA22 CA47 DA06 DA10 DA15 DA20 DB04 DB05 DB06 DB07 DB18 DB31 DC19 DC21 DC24 EA07 EB08 EB14 EB15 EB19 EB20 EB22 EB32 EB33 EB35 EB38 EB39 EB42 EB52 4F040 AA04 AA14 AB05 BA35 BA43 CC02 CC09 CC18 4F06 AACB ABA03 BA10

Claims (8)

[Claims] 1. An electrophotographic photoreceptor manufacturing apparatus having a coating tank for simultaneously immersing a plurality of cylindrical conductive substrates with a coating liquid, wherein the coating tank is formed by immersing a cylindrical conductive substrate. An opening through which the coating liquid overflows, the plurality of openings corresponding to the number of the cylindrical conductive substrates, and a smaller number of coating liquid supply ports than the openings are provided. An apparatus for manufacturing an electrophotographic photoreceptor, wherein the vertical distance is set lower as the distance from the liquid supply port increases. 2. The vertical positional relationship between a plurality of cylindrical conductive substrates to be simultaneously immersed and applied is set so as to be the same as the vertical positional relationship between the openings. 2. The apparatus for manufacturing an electrophotographic photosensitive member according to claim 1. 3. The apparatus according to claim 1, wherein the coating tank has a mechanism for individually adjusting a position of each of the openings in the vertical direction. 4. A mechanism according to claim 2, further comprising a mechanism capable of adjusting the position of each of the cylindrical conductive substrates so that the vertical positional relationship between the cylindrical conductive substrates can be changed. Electrophotographic photoreceptor manufacturing equipment. 5. The coating liquid according to claim 1, wherein the coating liquid is a coating liquid for a charge transport layer of a laminated electrophotographic photosensitive member.
5. The apparatus for manufacturing an electrophotographic photoreceptor according to any one of 4. 6. The apparatus according to claim 5, wherein the coating solution for the charge transport layer is a coating solution containing a non-halogen solvent. 7. The apparatus according to claim 5, wherein the coating liquid for the charge transport layer has a viscosity of 250 mP · s or more at 25 ° C. 8. A method for producing an electrophotographic photoreceptor, wherein a plurality of cylindrical conductive substrates are simultaneously immersed in a coating tank filled with a coating liquid to form a layer of the electrophotographic photoreceptor. A plurality of openings corresponding to the number of the cylindrical conductive substrates, and an opening where the coating liquid overflows by immersing the cylindrical conductive base, and a coating liquid supply port having a smaller number than the openings are provided. Each opening is arranged vertically lower as the distance from the coating liquid supply port increases, and each cylindrical conductive substrate is immersed in the coating liquid in the coating tank from the corresponding opening. A method for producing an electrophotographic photoreceptor.