JP2000321796A - Dip coating method and apparatus, photoreceptor, and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide an application method and an apparatus which do not cause coating defects such as shading unevenness, vertical streak-like color unevenness, and coating unevenness, and to provide an electrophotographic photosensitive member having excellent characteristics. SOLUTION: In a coating method of forming a coating film on an outer peripheral surface of a coating object by immersing the coating object in a coating liquid in a coating tank, the coating object is immersed in a coating liquid in the coating tank. During immersion, the relative velocity between the surface of the object and the moving or stationary coating solution in the application tank changes after the lower end of the object enters the application liquid in the application tank. It is a method and an apparatus for immersing while being immersed, and is useful for manufacturing an electrophotographic photosensitive member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dip-coating a coating on the surface of an object to be coated, and in particular, dip-coating a coating solution containing a photosensitive material on the outer peripheral surface of a cylindrical substrate for an electrophotographic photosensitive member. Thus, a uniform coating film is formed to provide an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art In recent years, organic photoconductive materials have been developed in electrophotographic photoreceptors, and they have been used more frequently than inorganic photoconductive materials which have been conventionally used. A photoreceptor using an organic material has some problems in sensitivity, durability, environmental stability, and the like, but has many advantages over inorganic materials in terms of toxicity, cost, flexibility in material design, and the like.

[0003] In general, organic electrophotographic photosensitive members are classified into a single-layer type and a function-separated (laminated) type. The laminated layer structure is composed of two or three layers. In the case of a two-layer structure, a charge generation layer is formed on a conductive substrate and a charge transport layer is formed thereon. An undercoat layer is provided on a substrate, and a charge generation layer and a charge transport layer are sequentially provided thereon. These photosensitive layers are prepared by dissolving or dispersing an organic photoconductive material for constituting each layer together with a binder resin in an organic solvent to prepare a photoconductor coating solution, and applying the photoconductor coating solution on a conductive substrate. And then dried.

[0004] As a coating method of an organic electrophotographic photosensitive member,
Examples include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dipping method. In particular, the dip coating method is a method of forming a photosensitive layer by immersing a conductive substrate in a coating tank filled with a photoreceptor coating solution and then pulling the conductive substrate at a constant speed or a gradually changing speed. Because of its superiority in terms of productivity and cost, it is often used in the production of electrophotographic photosensitive members.

In general, in the case of dip coating, the coating film thickness (wet film thickness) depends on the coating speed and the specific gravity and viscosity of the coating solution, and can be controlled by the coating speed and the specific gravity and viscosity of the coating solution. Specifically, in order to produce a photoreceptor with a thin film thickness, the viscosity of the coating solution is lowered, but the coating speed (pulling speed) is reduced (method).
Is mentioned.

[0006] During production, the dip coating is performed continuously while exchanging the substrate. However, during continuous application, a film is formed by evaporation of the solvent from the upper portion of the coating solution, dust is mixed in from the air, and the concentration of the coating solution is not uniform inside the tank, thereby causing a coating defect.

As a method of solving this drawback, a coating liquid whose liquid level has risen due to immersion of a substrate is overflowed from a coating tank.
An overflow method has been proposed in which the overflowed coating liquid is returned to a stirring tank, dust, coating, and the like are removed by filtration, a solvent and the like are added to adjust the viscosity, and then supplied to the coating tank again (Japanese Patent Application Laid-Open (JP-A)) 57-5047).

In the overflow method, the coating film thickness is 0.2 μm.
This is an effective method for forming a coating film having a thickness of not less than m (dry film thickness).
The flow of the coating liquid at the time of overflow causes unevenness in the coating film, which causes sensitivity unevenness, and lowers the yield of the electrophotographic photosensitive member. When a cylindrical substrate is immersed in a coating solution, the surface of the coating solution undulates when the substrate comes into contact with the liquid surface, causing a flow of the coating solution along the surface of the substrate, thereby causing streak-like unevenness in the coating film. .

When a coating film is formed with a high-viscosity coating liquid, unevenness in the distribution of the vapor layer concentration causes uneven leveling of the coating film in a wet state, resulting in uneven coating.

[0010] All of these coating irregularities are caused by the flow of the coating liquid when the cylindrical substrate is immersed in the coating liquid.
It is considered that the manner in which the coating liquid is adsorbed on the surface of the substrate affects the occurrence of unevenness in film thickness.

As a method for preventing the unevenness of the film thickness, a method of making the amount of the coating liquid overflowing from the coating tank from dipping to coating constant, is constant (Japanese Patent Laid-Open No. 07-1994).
89, JP-A-07-209885), and a circulation coating method using a device in which the shape of a coating tank is cylindrical and the area is continuously reduced from the upper part to the lower part (JP-A-05-337417).

As a method of making the vertical difference of the coating film uniform, a variable speed coating (Japanese Patent Application Laid-Open Nos. 57-5048 and 59-46) is known.
171 and Japanese Patent Application Laid-Open No. 03-78751).

As a similar patent, there is Japanese Patent Application Laid-Open No. 9-304949 filed with Konica Corporation.
An overflow dip coating method performed at 50 mm / sec is disclosed.

[0014]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a coating method and apparatus which do not cause coating defects such as shading unevenness, vertical streak-like color unevenness and coating unevenness, and provide an electrophotographic photosensitive member having excellent characteristics. The purpose is to provide.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided claims 1 to 1 for solving the above-mentioned problems.
(3) The invention according to (3).

According to the first and second aspects of the present invention, unevenness and vertical stripes close to the circumferential direction, which have conventionally been caused by immersing an object to be coated at a set constant speed (constant speed). This method does not cause any coating defects such as color unevenness and coating unevenness.

Claim 3 defines the range of the appropriate immersion speed in the above-described claims 1 and 2, and Claim 4 specifies the appropriate speed change condition (acceleration) when the immersion speed changes. Claim 5 defines an appropriate speed when the object passes through the vapor layer, and Claim 6 specifies an appropriate speed when the object enters the liquid surface of the coating liquid. It is specified.

Claim 7 relates to an apparatus suitable for the above-mentioned coating method, and Claim 8 defines an appropriate size of the coating tank.

A ninth aspect specifies a conductive support of an electrophotographic photosensitive member suitable as an object to be coated. A tenth aspect defines characteristics of a coating solution. This defines that the liquid is a charge transport layer coating liquid.

A twelfth aspect of the present invention is directed to an electrophotographic photosensitive member manufactured as described above, and a thirteenth aspect is directed to an image forming system for a copying machine, a facsimile or a printer using the electrophotographic photosensitive member. Is what you do.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of a dip coating apparatus in this system. A predetermined coating liquid 9 is stored in the coating tank 6, and the tray 3 is provided around a side wall 16 of the coating tank 6. The coating liquid 9 is sent out of the preliminary tank 8 by the liquid feed pump 10 and supplied through the filter 11 into the coating tank 6 from the supply port 12, and further passes over the upper edge of the side wall 16 in the circumferential direction of the coating tank 6. And is collected by the receiving tray 3 and discharged from the return pipe 7 to the preliminary tank 8. After the coating tank lid 2 is fully opened, the cylindrical substrate 1 starts immersion, passes through the vapor layer 5 and enters the coating liquid surface 15. Cylindrical substrate 1
After the lower end of the substrate enters the coating solution 9, the substrate is immersed while changing the speed.

The speed at which the cylindrical substrate 1 held by the support (not shown) descends to the position of the coating tank lid opening 4 in the operation when the cylindrical substrate 1 is immersed is referred to as the descending speed.
The speed from the coating tank lid opening 4 to above the coating liquid level 15 is referred to as a vapor layer entry speed (or a vapor layer passing speed). Coating liquid level 1
The speed at which the liquid enters the position No. 5 is referred to as a liquid entering speed. The speed at which the coating liquid surface 15 is immersed into the coating start position after entering the coating liquid surface 15 is referred to as the immersion speed (or the immersion speed in the liquid). In particular, the present invention is effective when applied over a layer containing a polymer as a main component, such as an undercoat layer, and is extremely effective when applying a pigment-dispersed paint onto a polymer layer. Although the reason for this has not been sufficiently analyzed, when dip coating is performed in a heterogeneous coating liquid such as a pigment-dispersed coating, the reflux of the vehicle due to evaporation of the solvent on the liquid surface, that is, a Bernard cell occurs. I do. It is considered that this Bernard cell is likely to occur when the evaporation concentration of the solvent is low, and the generation is slow when the concentration is high. If the object to be coated is immersed when the Bernard cell is generated, it is considered that the pattern adheres to the surface of the object to be coated, resulting in uneven coating. Further, it is considered that coating unevenness also occurs depending on how the overflow liquid flows during immersion. It is also assumed that the immersion speed is sensitive due to the influence of the surface tension of the object to be coated, the surface tension of the coating solution, or the wettability, and color unevenness and coating unevenness are likely to be detected.

When the immersion speed is constant (constant speed), if the speed is low, light and shade unevenness close to the circumferential direction is likely to occur, and if the speed is high, coating defects such as vertical stripe-like color unevenness and coating unevenness occur. I do.

In the case of the charge transport coating solution, if the immersion speed is constant (constant speed), if the immersion speed is low, the binder in the lower layer will be partially dissolved and will flow into the coating solution and become contaminated. or,
If the speed is high, coating defects such as bubbles (CTL protrusion) due to air entrainment occur.

In the present invention, when the object to be coated is immersed in the coating liquid in the coating tank, the surface of the object to be coated and the coating liquid that moves in the coating layer or is stationary in the coating tank. These coating defects can be eliminated by changing the relative immersion speed between the two. Preferably, immersion in which the object to be coated and the coating liquid are relatively accelerated is effective, and more preferably, the relative acceleration during immersion is set to 15 mm / s ² or less. As another acceleration method, it is also possible to accelerate immersion to a certain speed during immersion, and then immerse at a constant speed. For example, accelerated immersion from 5 mm / s to 80 mm / s
Immersion at a constant speed of mm / s. The changing speed is 1
It can be changed at less than 05 mm / s. Preferably 95 mm /
s or less is good. Further, when the object to be coated is immersed, it passes through the vapor layer, but if the speed at this time is higher than 10 mm / s, the vapor layer is disturbed and a Bernard cell is generated. 1mm
If the speed is lower than / s, the coating tank lid is open, so that the vapor concentration becomes low, and this also generates a Bernard cell. Preferably, it is 3 to 7 mm / s.

Next, the speed at which the object enters the coating liquid surface is preferably 1 to 10 mm / s for the same reason as the vapor layer passing speed. Preferably, the speed is 3 to 7 mm / s, but it is necessary to maintain the relationship: vapor layer passage speed ≦ coating liquid surface entry speed.

In the present invention, the layer containing a polymer as a main component means that the polymer contains 3 wt% or more of the total solid content in the film. In particular, when the content is 5 wt% or more, the effect of the present invention tends to be remarkable.

As the cylindrical substrate in the electrophotographic photosensitive member, aluminum, copper, gold, silver, platinum, palladium on a drum or sheet of metal such as aluminum, copper, iron, zinc and nickel, paper, plastic or glass A metal such as titanium, nickel-chromium, stainless steel, copper-indium, or a conductive metal oxide such as indium oxide or tin oxide; a metal foil laminated; or carbon black or indium oxide. A known material such as a drum-shaped, sheet-shaped, or plate-shaped material that has been subjected to conductive treatment by dispersing tin oxide-antimony oxide powder, metal powder, copper iodide, or the like in a binder resin and applying the same may be used. Although possible, the present invention is not limited to these.

Further, if necessary, the surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, oxidation treatment, chemical treatment, coloring treatment, and the like of the surface can be performed.

Further, an undercoat layer can be further provided between the conductive support and the charge generation layer, and the undercoat layer is provided at the time of charging from the conductive support in the photosensitive layer having a laminated structure to the photosensitive layer. In addition to preventing the injection of electric charges into the conductive support, the conductive layer functions as an adhesive layer for integrally bonding and holding the photosensitive layer to the conductive support, or functions to prevent light reflected from the conductive support. The resin used for the undercoat layer is polyethylene, polypropylene, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, polycarbonate, polyurethane,
Known resins such as polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, water-soluble polyester, nitrocellulose or casein, and gelatin can be used, but are not limited thereto. is not.

The undercoat layer has a thickness of 0.01 to 10 μm.
m, preferably 0.3 to 7 μm. Examples of the coating method used when the undercoat layer is provided include ordinary methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method. Can be

The charge generation layer (carrier generation layer) may be, for example, an azo dye such as a monoazo dye, a disazo dye or a trisazo dye; a perylene dye such as perylene anhydride or perylene imide; an indigo dye such as thioindigo; Polycyclic quinones such as quinone, pyrenequinone and flapanthrone, quinaglidone dyes, bisbenzimidazole dyes, indathrone dyes, squarylium dyes, metal phthalocyanines, phthalocyanine pigments such as metal-free phthalocyanines, pyrylium salt dyes, thiapyrylium Various known charge generating substances (carrier generating substances), such as a eutectic complex formed from a salt dye and polycarbonate, are dissolved or dispersed in a solvent together with a binder resin and, if necessary, a charge transporting substance (carrier transporting substance). Application It can be formed by Rukoto.

As a method for dispersing the charge generating material in the resin, a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or the like can be used. At this time, the charge generating substance has a volume average particle diameter of 5 μm or less, preferably 2 μm or less.
It is effective to set the particle size to not more than m, most preferably not more than 0.5 μm. As a solvent used for these dispersions, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, dioxane, Ordinary organic solvents such as tetrahydrofuran, methylene chloride, chloroform 1,2-dichloroethane, monochlorobenzene and xylene can be used alone or in combination of two or more.

The thickness of the charge generation layer used in the present invention is generally from 0.1 to 5 μm, preferably from 0.2 to 2 μm.

The charge transport layer in the electrophotographic photoreceptor of the present invention is formed by including a charge transport substance in a suitable binder. As the charge transport material, 2,5-bis (p
Oxazoazole derivatives such as -diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazolin, 1- [pyridyl- (2)]-
Pyrazoline derivatives such as 3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline; aromatic tertiary amino compounds such as triphenylamine, styryltriphenylamine and dibenzylaniline; N, N'- Aromatic tertiary diamino compounds such as diphenyl-N, N'-bis (3-methylphenyl) -1,1-biphenyl-4,4'-diamine; 3- (4'-dimethylaminophenyl) -5; 1,2, such as 6-di- (4'-methoxyphenyl) -1,2,4-triazine
4-triazine derivatives, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinzoline, 6-hydroxy-2,3-di (p-methoxyphenyl) -Benzofuran derivatives such as benzofuran, p- (2,2-diphenylvinyl)-
Α-Stilbene derivatives such as N, N-diphenylaniline, “Journal of Imaging Sci”
ence "29: 7-10 (1985), carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole such as poly-N-vinylcarbazole and derivatives thereof, poly-
γ-carbazolylethyl glutanate and derivatives thereof,
Further, known charge transporting substances such as pyrene, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-biphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin can be used, but are not limited thereto. Absent. These charge transporting substances may be used alone or
A mixture of more than one species can be used.

Further, as the binder resin in the charge transport layer, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, butylene-butadiene copolymer , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-almaldehyde resin, styrene-alkyd resin, Known resins such as poly-N vinylcarbazole can be used, but are not limited thereto. These binder resins can be used alone or in combination of two or more.

The mixing ratio (weight ratio) of the charge transporting material to the binder resin is preferably from 10: 1 to 1: 5. The thickness of the charge transport layer used in the present invention is generally 5 to 50 μm, preferably 10 to 30 μm.

Further, the solvent used for forming the charge transport layer includes aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, methylene chloride, chloroform, and chloride. Ordinary organic solvents such as halogenated aliphatic hydrocarbons such as ethylene, and cyclic or linear ethers such as tetrahydrofuran and ethyl ether can be used alone or in combination of two or more.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION The formulation of each liquid is specified below, and the present invention will be described in detail by giving examples with the liquid.

1. Formation of Undercoat Layer Coating Solution The following materials were dissolved to prepare an undercoat layer coating solution.

5 parts by weight of soluble nylon (Alamine CM
-8000, manufactured by Toray) 95 parts by weight of methanol 2. Preparation of Coating Solution for Charge Generating Layer 10 parts by weight of a charge generating agent represented by Structural Formula 1 7 parts by weight of polyvinyl butyral 145 parts by weight of tetrahydrofuran were put into a ball mill and milled for 72 hours. Further, 200 parts by weight of tetrahydrofuran was added and dispersed for 1 hour. The liquid after completion of the dispersion was further diluted and adjusted with tetrahydrofuran to prepare a charge generating layer coating liquid.

3. Preparation of charge transport layer coating solution 7 parts by weight of charge transporting agent shown in Structural Formula 2 10 parts by weight of polycarbonate (Panlite C
-1400, manufactured by Teijin Chemicals Co., Ltd. 83 parts by weight of dichloromethane were dissolved to prepare a charge transport layer coating solution.

Structural formula 1 Charge generation material

[0045]

Embedded image

Structural formula 2 Charge transport material

[0047]

Embedded image

Example 1 (Claims 1, 2, 3, 4, 7) A coating film is formed by immersing an aluminum cylindrical substrate having an outer diameter of 30 mm and a total length of 340 mm in an undercoat layer coating solution and pulling it up. Then, a charge generation layer and a charge transport layer were sequentially applied on the sample dried at 130 ° C. for 20 minutes, and the occurrence of coating film defects was evaluated. When forming the charge generation layer and the charge transport layer, coating was performed while changing the conditions of the immersion speed, the coating solution speed, and the relative acceleration within the ranges shown in the following table.

At this time, the immersion speed is a speed at which the cylindrical substrate enters the coating solution and then descends, and the coating solution speed is a flow speed of the coating solution flowing in the coating tank. Therefore, the coating liquid velocity has positive and negative values depending on the flowing direction of the coating liquid. In this case, the flow velocity when the coating liquid is flowing upward from below is represented by positive (+), and the coating liquid flows downward from above. The flow velocity when the liquid is flowing is represented by negative (-).

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

[Table 7]

[0057]

[Table 8]

[0058]

[Table 9]

[0059]

[Table 10]

[0060]

[Table 11]

[0061]

[Table 12]

[0062]

[Table 13]

[0063]

[Table 14]

[0064]

[Table 15]

[0065]

[Table 16]

[0066]

[Table 17]

[0067]

[Table 18]

[0068]

[Table 19]

Example 2 (Claim 5) A cylindrical substrate made of aluminum having an outer diameter of 30 mm and a total length of 340 mm was immersed in a coating liquid for an undercoat layer and pulled up to form a coating film, which was dried at 130 ° C. for 20 minutes. A charge generation layer and a charge transport layer were sequentially coated on the sample, and the occurrence of coating film defects was evaluated.

When forming the charge generating layer and the charge transporting layer, the coating was performed while changing the conditions of the vapor layer passing speed in the range shown in the following table.

[0071]

[Table 20]

[0072]

[Table 21]

Example 3 (Claim 6) An aluminum cylindrical substrate having an outer diameter of 30 mm and a total length of 340 mm was immersed in a coating liquid for an undercoat layer and pulled up to form a coating film, which was dried at 130 ° C. for 20 minutes. A charge generation layer and a charge transport layer were sequentially coated on the sample, and the occurrence of coating film defects was evaluated.

When forming the charge generation layer and the charge transport layer, the coating was performed by changing the conditions of the rush speed to the coating solution within the range shown in the following table.

[0075]

[Table 22]

Example 4 (Claim 8) A coating film is formed by immersing a cylindrical substrate made of aluminum in an undercoat layer coating solution and lifting it up, and forming a coating film at 130 ° C. for 20 mi.
The charge generation layer and the charge transport layer were sequentially applied on the sample dried for n times, and the occurrence of coating film defects was evaluated.

In forming the charge generation layer and the charge transport layer, when the outer diameter of the cylindrical substrate is d and the inner diameter of the coating tank is D, a is as shown in the following table. Was changed and applied.

A = ((D ² −d ² ) / D ² ) ^0.5

[0079]

[Table 23]

[0080]

According to the present invention, the coating film can be coated without coating defects such as coating unevenness, and a charge generating layer and a charge transport layer are coated on a conductive support of an electrophotographic photosensitive member. An electrophotographic photoreceptor having excellent characteristics can be provided by applying the technology.

[Brief description of the drawings]

FIG. 1 is a detailed view of a coating apparatus suitable for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical base body 2 Coating tank lid 3 Receiving tray 4 Coating tank lid opening 5 Solvent vapor layer 6 Coating tank 7 Return pipe 8 Preliminary tank 9 Coating liquid 10 Liquid sending pump 11 Filter 12 Supply port 13 Overflowing coating liquid 14 Return liquid 15 Coating liquid level 16 Side wall

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kiho Saito 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H068 AA21 AA26 EA16 EA20 4D075 AB02 AB12 AB37 AB52 AB56 CA48 DA15 DB01 DC27 EA45 4F040 AA07 AB06 BA47 CC02 CC09 DA03 DA12

Claims (13)

[Claims] 1. A coating method for forming a coating film on an outer peripheral surface of an object to be coated by dipping the object to be coated in a coating liquid in a coating tank. When immersing in the coating liquid, the lower end of the object to be coated enters the coating liquid in the coating tank, and then moves between the surface of the object to be coated and the coating liquid moving in the coating tank or stationary in the coating tank. A dip coating method characterized by immersing while changing the relative speed. 2. When the object to be coated is immersed in a coating liquid in a coating tank, at least a part of the object to be coated is intruded after the lower end of the object to be coated penetrates the coating liquid in the coating tank. 2. The dip coating method according to claim 1, wherein the dipping is performed while accelerating a relative speed between the surface of the object to be coated and the coating liquid moving in the coating tank or stationary in the coating tank. . 3. When the object to be coated is immersed in a coating solution in a coating tank, the lower end of the object to be coated enters the coating solution in the coating tank, and then the surface of the object to be coated and the inside of the coating tank are separated. 3. The method according to claim 1, wherein a relative speed between the moving liquid and the coating liquid that is stationary in the coating tank is in a range of 1 (mm / s) to 105 (mm / s). Dip coating method. 4. When the object to be coated is immersed in a coating solution in a coating tank, a lower end of the object to be coated penetrates the coating solution in the coating tank, and then the surface of the object to be coated and the inside of the coating tank are separated. 3. The dip coating method according to claim 1, wherein a relative acceleration between the coating liquid and a moving or stationary coating liquid in the coating tank is 15 (mm / s ² ) or less. 5. A dip coating method in which a photosensitive layer is formed on an outer peripheral surface of an object to be coated by immersing the object in a coating liquid. A production speed of the electrophotographic photoreceptor, wherein a speed of passing through the photosensitive member is 1 to 10 (mm / s). 6. A dip coating method in which a photosensitive layer is formed on an outer peripheral surface of an object to be coated by immersing the object in a coating solution, wherein a speed at which the object enters a liquid surface of the coating solution is applied. Is 1 to 10 (mm / s). 7. A coating tank for forming a coating film on the object by the coating method according to claim 1, a container for receiving the coating liquid overflowing from the coating tank, a tank for storing the coating liquid, and a coating tank. Equipped with a return pipe for sending the coating liquid from the container that receives the overflowing coating liquid to the tank that stores the coating liquid, and a pump and pipe for supplying the coating liquid from the tank that stores the coating liquid to the coating tank. And a device for controlling the circulating flow rate. 8. The dip coating apparatus according to claim 7, wherein
A dip coating apparatus characterized by satisfying the following formula, where D is the inner diameter of the coating tank and d is the outer diameter of the object to be coated. 0.21 ≦ ((D ² −d ² ) / D ² ) ^0.5 <1 9. The method for producing an electrophotographic photoreceptor according to claim 1, wherein said coating material has a layer containing a polymer as a main component on a conductive support. 10. The method according to claim 1, wherein the coating liquid is a pigment dispersion coating liquid. 11. The method according to claim 1, wherein the coating liquid is a charge transport layer coating liquid. 12. An electrophotographic photosensitive member manufactured by the dip coating method according to claim 1. 13. A copying machine characterized by using an electrophotographic photosensitive member produced by the dip coating method according to claim 1.
Facsimile or printer imaging system.