JPH09160266A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing an electrophotographic photoreceptor which is free from coating defects and has good electrical characteristics and image characteristics and excellent sensitivity and printing resistance. SOLUTION: This process comprises forming a charge generating layer and a charge transfer layer in this order on a substrate 3 for the electrophotographic photoreceptor. In dip-coating the substrate 3 for the electrophotographic photoreceptor with the charge generating layer, the average flow velocity at which a coating material for forming the charge generating layer rises in the gap between the substrate 3 for the electrophotographic photoreceptor and a coating vessel 6 is kept in a range from 0.1 to 0.5m/min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photosensitive member. More specifically, the present invention relates to a method for producing a function-separated electrophotographic photosensitive member which has no coating defects, has excellent electrical characteristics and image characteristics, and has excellent sensitivity and printing durability.

[0002]

2. Description of the Related Art In recent years, electrophotographic photoreceptors have advantages in many aspects such as safety, easiness of a production process, and production costs. Therefore, selenium, cadmium sulfide, zinc oxide, etc. Inorganic electrophotographic photoreceptors using inorganic materials as photoconductors have been widely used.

Electrophotographic photoreceptors are generally classified into a single-layer type and a function-separated type (multilayer type), but the function-separated type electrophotographic photoreceptor is the mainstream at present because of its superior sensitivity. There is. In the layer structure of the function separation type, first, a charge generation layer and a charge transport layer are sequentially formed on a photoreceptor substrate. An undercoat layer may be provided on the surface of the substrate as needed, and an overcoat layer may be formed on the charge transport layer as needed.

In recent years, since the functions of copying machines, laser printers, etc. have been remarkably enhanced, electrophotographic photoreceptors constituting the main parts thereof are also required to be highly sensitive. The following two methods can be considered as the methodology for increasing the sensitivity of the electrophotographic photosensitive member. That is, (1) improvement of quantum efficiency of the charge generation layer and (2) improvement of charge transport ability of the charge transport layer.

Regarding the former, since quantum efficiency is a characteristic peculiar to the charge generating material, it is difficult to improve quantum efficiency and increase sensitivity by changing the manufacturing conditions of the electrophotographic photosensitive member. . However, regarding the latter method, by thinning the charge generation layer on the electrophotographic photosensitive member, in the electrophotographic process, the speed at which electrons move from the charge generation layer to the electrophotographic photosensitive member substrate is increased, and Studies have been conducted to improve the sensitivity of the body, and they have been put to practical use.

Further, in the case of producing an electrophotographic photosensitive member, as a method for forming a coating film on a cylindrical supporting substrate using a coating material for forming an electrophotographic photosensitive member, a dip coating method, a spray coating method, a nozzle coating method, Curtain coating method, roll coating method, blade coating method, spiral coating method, ring coating method and the like are known. Among these, the dip coating method is a method in which a substrate for an electrophotographic photosensitive member is placed in a coating tank filled with a coating material for forming an electrophotographic photosensitive member at a constant speed or a sequentially changing speed or a combination of a constant speed and a sequentially changing speed. After soaking
This is a method of forming a photosensitive layer by applying a coating for forming a photosensitive layer on the surface of the photosensitive body substrate by pulling up the photosensitive body substrate at a constant speed or a speed that changes sequentially or a combination of a constant speed and a speed that sequentially changes.

Since this dip coating method does not require complicated equipment and is superior in productivity and cost to other methods, it is widely used in the production of electrophotographic photoreceptors. In continuous coating in a production line using the dip coating method, the following two methods are usually used as a method for controlling the film thickness of the photosensitive layer formed on the surface of the electrophotographic photosensitive member, that is, the charge generation layer and the charge transport layer. Is done.

(1) Method of changing the pulling rate of the electrophotographic photosensitive member substrate (2) Method of changing the concentration of the coating material for forming the charge generating layer or the charge transport layer The basis of these methods is that the substrate is formed by the dip coating method. The following relationship may be established between the film thickness of each photosensitive layer formed on the surface, the pulling rate, and the concentration of the coating material for forming the photosensitive layer.

[0009]

[Equation 1]

Μ: Film thickness of the formed photosensitive layer k, α: Constant C: Concentration (wt%) of coating material for forming photosensitive layer η: Viscosity of coating material for forming photosensitive layer Vc: Lifting speed of photoreceptor substrate

From the formula [1], the film thickness of the photosensitive layer can be changed by changing the concentration or viscosity of the coating material for forming the photosensitive layer, or the pulling rate of the photosensitive substrate. However, if the concentration or viscosity of the photosensitive layer-forming coating material is changed, the formation of the photosensitive layer may be adversely affected. For example, when the concentration or viscosity of the charge generation layer-forming coating material is reduced during continuous operation on a production line, coating unevenness or pigment overdispersion or aggregation may occur. When the concentration or viscosity of the coating material for forming the charge transport layer is reduced, the thickness of the charge transport layer becomes non-uniform or the drop zone of the electrophotographic photoreceptor becomes large, and the image area is limited. Occurs. Conversely, when the concentration or viscosity of the coating material for forming a photosensitive layer is increased, the same photosensitive layer thickness cannot be maintained unless the pulling speed of the photosensitive member substrate is reduced, thereby lowering productivity. .

Therefore, the above-mentioned method (2) for controlling the film thickness is usually not carried out during continuous operation on the production line, and the method (1) is mainly used for controlling the film thickness of the photosensitive layer. .
There are several dip coating methods depending on the method of supplying the coating material for forming the photosensitive layer to the coating layer. Here, each method will be described below, focusing on the method of supplying the coating material for forming the photosensitive layer.

(1) A method (non-overflow method) in which the coating material for forming the photosensitive layer, which is used in one coating step, is sequentially added to the coating tank. (2) During the coating step, in a step other than the step of dipping / pulling up the photoconductor substrate, a method of continuously replenishing the coating tank with a constant amount or a variable amount of the photosensitive layer-forming coating material (temporary overflow method) ). (3) A method in which a constant amount or a continuously changing amount of the photosensitive layer-forming coating material is continuously supplied to the coating tank through the coating step to constantly overflow the coating material (constant overflow method). In these three methods, the photosensitive layer-forming coating material overflowing from the coating tank by immersing the photosensitive substrate in the coating tank is once collected in a hold tank and replenished with a solvent or the like. It is supplied to the coating tank after being sufficiently stirred to prepare a photosensitive layer-forming coating material having a uniform concentration and viscosity and uniform.

However, the supply methods (1) and (2) are the inner wall of the coating tank, the inner surface of the pipe, the inlet portion for guiding the overflowed photosensitive layer forming coating material to the hold tank, and the like. Since it is dried to a certain extent, uneven density occurs in the photosensitive layer-forming coating material, and it is unavoidable that a dried coating film or minute dust is mixed in the photosensitive layer-forming coating material, and it is possible to remove minute dust particles. It was found that a large facility burden was required on the stirring / circulation system for uniformizing the coating for forming the photosensitive layer, and it was also inferior to the method of (3) in terms of quality, quality control and production efficiency. ing.

In the supply method of (3), since the photosensitive layer forming coating material is continuously supplied to the coating tank even in the dipping / coating process, the capacity of the supply pump (quantitative, non-pulsating), the coating tank It is known that the quality of the product is largely influenced by the flow pattern inside, the flow velocity / flow rate, the shape of the coating tank, the rectification method in the coating tank, and the like. Particularly, in the method (3), the step of forming the charge generation layer on the electrophotographic photosensitive member substrate (immersion /
In the coating step), a phenomenon that streak-shaped coating defects extending in the longitudinal direction of the drum were generated in the charge generation layer was observed.

It is generally known that this phenomenon is more likely to occur as the film thickness of the charge generation layer is smaller, and conventionally, a method of preventing this coating defect is performed by increasing the film thickness of the charge generation layer. I've been told. Dry film thickness of charge generation layer is 1.2μm
It is known that such coating unevenness hardly occurs when the above setting is made. However, as described above, the thinning of the charge generation layer has been proposed as a means for increasing the sensitivity of the electrophotographic photosensitive member, and since it has been put into practical use, measures for preventing the occurrence of these coating defects are required.

[0017]

As described above, the constant overflow method is used to increase the sensitivity in the step (immersion / coating step) of forming the charge generation layer on the electrophotographic photoreceptor substrate. When the film thickness of the charge generation layer is thin, there is a problem that streak-shaped coating defects extending in the longitudinal direction (immersion and coating direction) of the photoconductor substrate are likely to occur in the charge generation layer. This is a coating for forming a photosensitive layer in the gap between the coating tank and the photosensitive substrate when the electrophotographic photosensitive substrate is immersed in the coating for forming a photosensitive layer in the dipping / coating process. However, a non-uniform flow is generated in the upward flow, and the non-uniform flow remains on the surface of the photoconductor substrate as a trace in the flow direction. These streak-shaped coating defects appear as white streak unevenness on the surface of the electrophotographic photosensitive member as compared with the normal portion.

On the other hand, in the non-overflow method and the temporary overflow method, the coating for forming the photosensitive layer is not supplied in the dipping step and the subsequent coating step by pulling up the photoreceptor substrate. Therefore, as the photosensitive body substrate is pulled up, a region containing a large amount of solvent vapor of the photosensitive layer-forming coating material is inevitably formed in the void formed by the coating tank and the photosensitive body substrate, and is formed on the surface of the photosensitive body substrate. Due to the leveling effect in the area containing a large amount of these solvent vapors, the charge generation layer is streaked due to non-uniform upward flow when the electrophotographic photoreceptor substrate is dipped in the coating solution for forming the photosensitive layer. Even when the coating defects described above occur, these coating defects are alleviated. For this reason, it has been known that the non-overflow method and the temporary overflow method are unlikely to cause streak-shaped coating defects extending in the longitudinal direction of the photoreceptor substrate. However, even with these methods, it has been found that the stripe-shaped coating defects cannot be completely alleviated because the coating upper end portion of the photoreceptor substrate passes through a region containing a large amount of solvent vapor for a short time.

Based on the above knowledge, the following two methods are conceivable as approaches for solving this problem. That is, (1) a method is developed in which even if streaky coating defects occur on the surface of the photoreceptor substrate due to nonuniform upflow, they are eliminated by the leveling effect of the solvent vapor. (2) Develop an immersion method that does not generate uneven upflow

First of all, regarding the method (1), even if the method is always the overflow method, if a portion filled with the solvent vapor of the photoconductor-forming paint is provided in the upper part of the coating tank, the leveling effect will result. , Is based on the assumption that it is possible to mitigate various coating defects including streak-shaped coating defects extending in the longitudinal direction of the photoreceptor substrate, and an example of such coating defect countermeasures. Also exists. (See Japanese Patent Laid-Open No. 4-255858). However, it is difficult to think that these methods are preferable because they require a large facility burden and require the control of the solvent vapor concentration in the solvent vapor tank and the control of the air flow. Therefore, in the following method (2), only the streak-like coating defects due to the non-uniform upward flow are focused, and the effect on the other coating unevenness different from the method (1) is not considered. The study was conducted in the direction of avoiding complications due to the increase in the workload and the addition of new management items as much as possible.

[0021]

As a result of various investigations by the present inventors to prevent the occurrence of the above-mentioned streak-shaped coating defects, when the electrophotographic photoreceptor substrate is dipped in a charge generation layer forming coating material, Generated in the longitudinal direction (immersion or coating direction) of the electrophotographic photoreceptor substrate by keeping the average flow velocity of the charge generation layer forming paint rising in the gap between the photographic photoreceptor substrate and the coating tank within a specific range. The present invention has been achieved by knowing that the effect of preventing streaky coating defects is obtained. That is, the gist of the present invention is a method for producing an electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a conductive electrophotographic photoreceptor substrate, in which the charge generation layer is provided on the electrophotographic photoreceptor substrate. At the time of dip coating, the average flow rate at which the charge generation layer-forming coating material rises in the space between the electrophotographic photoreceptor substrate and the coating tank is 0.
A method for producing an electrophotographic photosensitive member is characterized by maintaining the range of 1 to 0.5 m / min.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 is an explanatory diagram of a dip coating method of a constant overflow method which is an example of the present invention. The photoconductor substrate 3 vertically suspended by the photoconductor substrate holding device 2 of the coating machine 1 is filled in the coating tank 6 by lowering the vertically movable arm 5 by the rotation of the lifting motor 4. It is dipped in the photosensitive layer forming coating material 7 thus prepared (immersing step). Here, the photosensitive layer forming paint 7 overflowing from the upper end of the coating tank 6 and flowing down to the paint receiving portion 8 is collected in a hold tank 9 through a pipe. Subsequent to the dipping process, the arm 5 is vertically lifted by the rotation of the lifting motor 4 to perform the coating (coating process). During this time, since the photosensitive layer forming coating material 7 is continuously supplied by the photosensitive layer forming coating material supply pump 10, the liquid level in the coating tank 6 does not descend.
Therefore, the upper end surface of the coating tank 6, the inner surface of the coating tank 6, the paint receiving portion 8 and the paint contacting portion of the pipe are not dried, and the dried coating film pieces are prevented from being mixed in the photosensitive layer forming paint 7. Get off. Paint 7 for forming photosensitive layer collected in hold tank 9
Hold tank 9 after adding a very small amount of volatile solvent
The mixture is uniformly stirred and mixed by using the internal stirring device, and is supplied from the bottom of the coating tank 6 through a filter 11 for removing dust mixed in when passing through the photosensitive layer forming paint supply pump 10. .

The feature of the present invention is that when the photosensitive body substrate is immersed in the photosensitive layer-forming coating material filled in the coating tank, the photosensitive layer-forming coating material that is extruded is separated from the inner wall of the coating tank and the photosensitive body substrate. The average flow velocity that rises through the voids is 0.1 to 0.5 m / mi
n, more preferably in the range of 0.2 to 0.4 m / min, to make the flow of the photosensitive layer-forming coating material overflowing from the upper part of the coating tank substantially uniform, and to identify the cause of streaky coating defects. The non-uniform and strong flow of is not generated.

Here, as a method for uniformizing the flow of the coating material for forming the photosensitive layer overflowing from the upper part of the coating tank, (1) the immersion speed of the photosensitive substrate is reduced. (2) Use a coating tank having an opening area sufficiently large with respect to the cross-sectional area of the photoreceptor substrate. (3) In the step of immersing the photoconductor substrate, the supply of the photosensitive layer forming coating material is stopped from the bottom of the coating tank or the photosensitive layer forming coating material is gradually discharged. And the like or a combination of these means.

The method (1) is not a preferable method from the viewpoint of productivity. In addition, the method of (2)
When the ratio between the cross-sectional area of the photoconductor substrate and the opening area of the coating tank exceeds a certain limit value, a specific coating defect tends to occur depending on the excess value. Therefore, it is actually preferable to combine the methods (1) to (3).

As the substrate for the electrophotographic photosensitive member in the present invention, any of those which are adopted in known electrophotographic photosensitive members can be used as long as they are conductive. Specifically, a metal cylindrical substrate made of aluminum, nickel, stainless steel, copper or the like, a sheet or a laminate of these metal foils, or a substrate made of glass, plastic, paper or the like is vapor-deposited with these metals so as to have conductivity. And the like. Further, a conductive material such as metal powder, carbon black, copper iodide, or a polymer electrolyte is surface-coated with an appropriate binder to perform a conductive treatment, or a conductive material containing metal powder, carbon black, carbon fibers, or the like is used. And a cylindrical or film-like substrate made of paper or the like.

As the electrophotographic photoreceptor substrate, various substrates containing aluminum as a main component are particularly preferable. For example, as a material of a material mainly containing aluminum, J
Pure aluminum such as IS1050, JIS1070, JIS1080 or Al-Mg alloy, Al-Cu alloy, Al-Si alloy, Al-Mg-Si alloy, Al
-Cu-Si alloys and other various aluminum alloys, more preferably Al-Mn alloys JIS3003, Al
JIS6063 etc. which are -Si type alloys are mentioned.

The photoreceptor base made of aluminum is
It is molded by surface cutting or ironing.
Further, those obtained by subjecting these photoreceptor substrates to heat treatment and then alumite treatment are also exemplified. As the photosensitive layer of the electrophotographic photosensitive member, a function separation type photosensitive layer having a structure in which a charge generation layer and a charge transport layer are laminated is used.

As the electrophotographic photosensitive member-forming coating material in the present invention, a photosensitive layer-forming coating material containing a charge generating material and / or a charge transporting material is used. In the case of a function-separated type photosensitive layer, a charge generation layer and a charge transport layer are sequentially formed on the above electrophotographic photosensitive substrate, but an undercoat layer is provided on the photosensitive substrate as required. The coating material for forming the undercoat layer is, for example, polyvinyl alcohol,
Polymeric materials such as casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, polyvinyl butyral, phenoxy resin, polycarbonate, polyvinylcarbazole alone, or copolymers thereof are suitable solvents. That is, it is prepared by dissolving in water, various alcohols, ethers, ketones, hydrocarbons and the like. The undercoat layer is formed by applying and drying the undercoat layer forming paint on the photoreceptor substrate. If necessary, various inorganic oxides such as silica, alumina, zinc oxide, titanium oxide, indium oxide, tin oxide and various organic pigments are added to the undercoat layer.

As the charge generating material used in the charge generating layer, azo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments, cyanine pigments, squarylium pigments, perinone pigments, perylene pigments,
Anthraquinone pigment, polycyclic quinone pigment, indigoid pigment, phthalocyanine pigment, carbonium pigment, quinoneimine pigment, methine pigment, quinoline pigment, nitro pigment, nitroso pigment, benzoquinone and naphthoquinone pigment, naphthalimide Known charge generating materials such as pigments and bisbenzimidazole pigments can be used. These charge generation materials are various known binder resins,
By dispersing in a suitable organic solvent containing a sensitizer and the like, a charge generation layer forming coating material can be obtained. These charge generation layer forming paints are applied by the method described above to form a charge generation layer.

The charge transport material is not particularly limited, and an electron transport medium or a hole transport medium can be used, and a mixture thereof can also be used. As an electron transport medium, an electron-withdrawing compound having an electron-withdrawing group such as a nitro group, a cyano group, an ester group, for example, 2,4,6-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, etc. Examples thereof include nitrated fluorenones, tetracyanoquinodimethane, and diphenoquinone derivatives. Further, as a hole transport medium, an electron-donating organic photoconductive compound, for example, carbazole, indole,
Heterocyclic compounds such as imidazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole, triphenylmethane and its derivatives, triphenylamine and its derivatives, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, hydrazone derivatives Alternatively, polymer materials having these structures in the main chain or side chain may be mentioned. These charge transporting materials are dispersed or dissolved in a suitable organic solvent containing various known binder resins and other additives to obtain a coating material for forming a charge transporting layer. These charge transport layer forming paints are applied by the method described above to form a charge transport layer.

Solvents for preparing the above-mentioned coating material for forming the charge generating layer or the charge transporting layer include N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, 4-methoxy-4-methylpentanone-2 and dimethoxymethane. , Dimethoxyethane, benzene, toluene, xylene, chloroform, dichloromethane, 1,2
-Dichloroethane, tetrahydrofuran, 1,4-dioxane, methanol, ethanol, 2-propanol,
Ethyl acetate, butyl acetate, dimethyl sulfoxide, 2,
4-pentanedione, methyl 3-oxobutanoate and the like can be mentioned. The above-described method of manufacturing an electrophotographic photosensitive member according to the present invention has a very remarkable effect of suppressing the occurrence of coating defects when the charge generation layer is formed by the dip coating method using the always overflow method. Therefore, it is possible to manufacture an electrophotographic photoreceptor having good image characteristics with less coating unevenness and variation in sensitivity.

[0033]

The present invention will be described in more detail with reference to the following examples. In the following, “parts” means “parts by weight”. Example 1 A conductive cylindrical substrate made of aluminum was prepared as a substrate for an electrophotographic photoreceptor, and a charge generating layer forming coating material and a charge transporting layer forming coating material prepared in the following manner were sequentially applied to this surface. It was dried to prepare an electrophotographic photoreceptor. First, a paint for forming a charge generation layer was prepared as follows.
That is, 4 parts of a phthalocyanine compound represented by the following structural formula (1), 1 part of polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo KK, trade name # 6000-C), phenoxy resin (manufactured by Union Carbide Co., trade name PKHH) 1 copy,
360 parts of dimethoxyethane and 4-methoxy-4
-Methylpentanone-2 40 parts

[0034]

Embedded image

Dispersion treatment and mixing and dissolution were carried out with a sand grinder mill to prepare a charge generation layer-forming coating material having a viscosity of about 2.0 centipoise. The charge generation layer-forming coating material is applied to the outer peripheral surface of the conductive cylindrical substrate so that the dry film thickness is 0.1.
The charge generation layer was formed by performing dip coating under the conditions described below so as to have a thickness of 0 μm. Next, an example of the charge transport layer forming coating material will be given below.

76 parts of the hydrazone compound represented by the following structural formula (2), 19 parts of the hydrazone compound represented by the following structural formula (3), 100 parts of the polycarbonate resin represented by the following structural formula (4), and the following structure 1.5 parts of the compound represented by the formula (5), 70 parts of tetrahydrofuran, and 1,4-
30 parts dioxane

[0037]

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[0038]

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[0039]

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[0040]

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Mix and dissolve in a separable flask to
A charge transport layer-forming coating material having a viscosity of 50 centipoise was obtained. Then, this charge transport layer-forming coating material was applied on the surface of the charge generation layer by dip coating so that the dry film thickness was 22 μm, and then dried at 125 ° C. for 48 minutes to form an electrophotographic photoreceptor.

The coating conditions for the charge generation layer are as follows. -Outer diameter of photoconductor substrate: 150 (mm) -Inner diameter of coating layer: 195 (mm) -Dip speed of photoconductor substrate: 3.3 (mm / sec) -Charge generation layer during dipping of photoconductor substrate No forming paint is supplied. When the dip coating was performed under the above conditions, a uniform electrophotographic photosensitive member having no streak-shaped coating defects in the charge generation layer was obtained. This was installed in an actual copying machine and the copying process was repeated. As a result, a good image with less image unevenness due to streak application defects was obtained.

Example 2, Comparative Examples 1 to 3 By changing the condition of the dipping speed of the photoconductor substrate, the average flow velocity at which the charge generation layer forming coating material rises in the gap between the photoconductor substrate and the coating tank is set. The same procedure as in Example 1 was carried out except that it was changed. The results are shown below together with Example 1.

[0044]

[Table 1]

The flow velocity specified in the present invention, that is, the average flow velocity of the charge generation layer forming coating material between the substrate and the coating tank when the photoreceptor substrate is immersed is 0.1 to 0.5 (m / min). When the condition is satisfied, no streak-shaped coating defects occur and an electrophotographic photosensitive member having good image characteristics can be obtained.
If the conditions are not satisfied, streak-shaped coating defects and coating defects due to the generation of non-uniform flow showing other shapes occur, and not only the yield is lowered but also an electrophotographic photoreceptor having good image characteristics. Was hardly obtained.

Example 3 In the same manner as in Example 1, a conductive cylindrical substrate made of aluminum was prepared as an electrophotographic photosensitive substrate, and on the surface of this, a conductive cylindrical substrate was prepared.
The charge generation layer-forming coating material and the charge transport layer-forming coating material prepared as described below were sequentially applied and dried to prepare an electrophotographic photoreceptor. First, the charge generation layer-forming coating material was prepared as follows, that is, 4 parts of a bisazo compound represented by the following structural formula (6), polyvinyl butyral resin (trade name # 6000-C manufactured by Denki Kagaku Kogyo KK). ) 2 parts, phenoxy resin (manufactured by Union Carbide Co., trade name PKHH) 1
Parts, 360 parts of dimethoxyethane, and 4-methoxy-
4-methylpentanone-2 40 parts

[0047]

[Chemical 6]

Dispersion treatment and mixing and dissolution were carried out with a sand grinder mill to prepare a charge generation layer forming coating having a viscosity of about 2.0 centipoise. The charge generation layer-forming coating material is applied to the outer peripheral surface of the conductive cylindrical substrate so that the dry film thickness is 0.1.
The charge generation layer was formed by performing dip coating under the conditions described below so as to have a thickness of 8 μm.

Next, one example of the coating material for forming the charge transport layer will be described below. 110 parts of the hydrazone compound represented by the following structural formula (7), 100 parts of the polycarbonate resin represented by the structural formula (4), 1.5 parts of the compound represented by the following structural formula (8), and the following structural formula ( Antioxidant 2 represented by 9)
Parts, tetrahydrofuran 70 parts, and 1,4-dioxane 30 parts

[0050]

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[0051]

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[0052]

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The above components were mixed and dissolved in a separable flask to obtain a charge transport layer-forming coating material having a viscosity of about 250 centipoise. Then, the coating material for forming a charge transport layer was applied by dip coating on the surface of the charge generation layer so that the dry film thickness became 35.0 μm, and then dried at 130 ° C. for 48 minutes to form an electrophotographic photosensitive member.

The coating conditions for the charge generation layer are as follows. -Outer diameter of photoconductor substrate: 100 (mm) -Inner diameter of coating layer: 155 (mm) -Dip rate of photoconductor substrate: 5.0 (mm / sec) -Charge generation layer when dipping the photoconductor substrate No forming paint is supplied. When the dip coating was performed under the above conditions, a uniform electrophotographic photosensitive member having no streak-shaped coating defects in the charge generation layer was obtained. This was installed in an actual copying machine and the copying process was repeated. As a result, a good image with less image unevenness due to streak application defects was obtained.

Examples 4, Comparative Examples 4 and 5 By changing the conditions of the immersion speed of the photoconductor substrate, the average flow velocity at which the paint for forming the charge generation layer rises in the gap between the photoconductor substrate and the coating tank is set. The same procedure as in Example 3 was carried out except that it was changed. The results are shown below together with Example 3.

[0056]

[Table 2]

Also from this result, when the conditions prescribed in the present invention are satisfied during the dip coating, coating defects do not occur. On the other hand, when the conditions are not satisfied, streak-shaped coating defects occur. It is understood that the yield was significantly reduced due to the occurrence of.

[0058]

EFFECTS OF THE INVENTION By using the conditions at the time of dipping in the coating process defined by the present invention, there are no coating defects, good electric characteristics and image characteristics, and excellent sensitivity and printing durability. It is possible to provide a method for producing a function-separated electrophotographic photoreceptor.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an example of the present invention.

[Explanation of symbols]

 1 Coating Machine 3 Electrophotographic Photosensitive Body Substrate 6 Coating Tank 7 Photosensitive Layer Forming Paint

Claims (2)

[Claims] 1. A method for producing an electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a conductive electrophotographic photoreceptor substrate, wherein the charge generation layer is dip-coated on the electrophotographic photoreceptor substrate. At this time, the electrophotography characterized by maintaining the average flow velocity of the charge generation layer forming coating in the space between the electrophotographic photoreceptor substrate and the coating tank within a range of 0.1 to 0.5 m / min. Manufacturing method of photoconductor. 2. The method for producing an electrophotographic photoreceptor according to claim 1, wherein the charge generation layer is applied while the coating material for forming the charge generation layer is always overflowed from the coating tank.