JPH0862868A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE: To produce an electrophotographic photoreceptor having a uniform photosensitive coating film free of defects. CONSTITUTION: A cylindrical substrate 1 is vertically lowered into a dipping tank 2 from which a coating soln. 5 is overflowing, and dipped in the soln. 5, and then the substrate 1 is vertically raised and dip-coated. In this case, a partition cylindrical tube 10 kept out of contact with the periphery of the substrate 1 and capable of forming a clearance between it and the inner wall of the tank 2 is arranged around the entering path of the substrate 1, the tube 10 is raised or lowered almost at the same time that the substrate 1 is dipped to shield the coating soln. 5 surface, and the tube 10 is raised or lowered immediately before the substrate 1 is pulled up or at the same time that the substrate is pulled up not to shield the coating soln. 5 surface.

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, and more particularly to a method for manufacturing an electrophotographic photosensitive member having a uniform photosensitive coating film without coating defects.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is manufactured by applying a coating solution of a photosensitive material on the outer peripheral surface of a cylindrical substrate and then drying it to form a photosensitive coating film on the surface of the cylindrical substrate. . As a coating method, a dip coating method in which a cylindrical substrate is vertically lowered and dipped in a dipping tank containing a coating liquid, and then the cylindrical substrate is vertically raised and pulled up is preferably adopted.

[0003]

However, although various dip coating methods have hitherto been proposed, there is a problem in that the method causes a specific coating defect.
Such coating defects are not particularly problematic in a solution-based coating liquid, that is, a coating liquid for a charge transport layer in the case of manufacturing a laminated electrophotographic photoreceptor, but a dispersion-based coating liquid, that is,
This is remarkable in a coating liquid containing a charge generating substance such as an azo pigment, particularly in a coating liquid for a charge generating layer in the case of manufacturing a laminated electrophotographic photoreceptor.

Regarding the above coating defects, FIG. 4 and FIG.
A description will be given based on (a) to (c). FIG. 4 is an explanatory diagram of an example of a conventional dip coating method, and FIGS. 5A to 5C are explanatory diagrams showing the form of coating defects of the photosensitive coating film.

The conventional dip coating method shown in FIG. 4 is a method in which a cylindrical substrate is dipped and pulled up in an overflowing coating solution. The coating liquid (5) is the coating liquid supply port (3)
The coating liquid supplied to the dipping tank (2) from the overflowing portion (6) of the dipping tank (2) and overflowing to the overflow coating liquid receiving toy (4) is
It is sent to the coating liquid tank (7) and the coating liquid supply pump (8)
Is again supplied to the dipping tank (2). Then, the coating liquid (5) is applied to the outer peripheral surface of the cylindrical substrate (1) by immersing the cylindrical substrate (1) in a dipping tank (2) in which the coating liquid overflows and pulling it up. The reference numeral (9) in the figure indicates an overflow coating liquid receiving toy (4).
It is the hood provided on the top.

In the conventional dip coating method shown in FIG. 4, since the cylindrical substrate is pulled up while the coating solution overflows,
There is an advantage that the coating thickness of the coating liquid can be made constant by controlling only the rising speed of the cylindrical substrate, and as a result, coating can be performed with high productivity.

However, in the case of the conventional dip coating method shown in FIG. 4, overflow of the coating solution causes the coating solution to flow along the surface of the cylindrical substrate, which is called flow unevenness as shown in FIG. 5 (a). Coating defects occur. In particular,
Such coating defects are likely to occur when the cylindrical substrate is dipped.

In order to solve the above-mentioned inconvenience, in a method of applying a coating liquid to a cylindrical substrate by immersing the cylindrical substrate in the overflowing coating liquid and pulling up the cylindrical substrate from the coating liquid, The following proposals (1) to (3) have been made.

(1) A cylindrical partition member, which is larger than the outer diameter of the cylindrical substrate and smaller than the inner diameter of the cylindrical substrate and longer than the cylindrical substrate, is provided in the dipping tank, and the upper end of the partition member overflows the dipping tank. Immersion coating device installed at a position higher than the partition part, with a coating liquid inflow / outflow hole provided in the lower part of the partition member so that the coating liquid in and out of the partition member can flow in / out through the outflow / outflow hole, and overflows only outside the partition member. (Japanese Patent Publication No. 5-45951).

(2) A partition cylindrical tube having a diameter larger than the diameter of the cylindrical substrate and smaller than the inner diameter of the immersion tank is provided in the immersion tank.
A method of using a dip coating device installed so that the upper end of the partition cylindrical tube is located above the upper end of the dipping tank and the lower end of the partition cylindrical tube is located below the upper end of the dipping tank (JP-A-5-72760).
Issue).

(3) A cylindrical pseudo bath having an inner diameter suitable for the outer diameter of the cylindrical substrate and being removable, and having a large number of through holes through which the coating liquid can freely pass, is placed in the dipping tank. A method of using a dip coating apparatus which is arranged and is capable of changing the number of cylindrical substrates which can be coated at one time in one dipping tank according to the outer diameter of the cylindrical substrate (JP-A-5-8).
8384).

However, in the method disclosed in Japanese Patent Publication No. 5-45951, the coating liquid is settled inside the partition member because the flow of the coating liquid is insufficient.
As a result, coating defects called coating streaks as shown in FIG. 5B occur on the surface of the cylindrical substrate dipped inside the partition member.

Further, according to the methods described in JP-A-5-72760 and JP-A-5-88384, in order to coat with good productivity, when the cylindrical substrate is pulled up while overflowing the coating liquid, the cylindrical substrate is used. By vibrating the surrounding coating liquid surface, the surface of the cylindrical substrate is shown in FIG.
A coating defect called horizontal unevenness occurs as shown in FIG.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing an electrophotographic photosensitive member having a uniform photosensitive coating film without coating defects.

[0015]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have found that, by vertically moving a partition cylindrical pipe at a specific timing, uneven flow due to overflow and coating liquid are caused. From the above, it was found that the horizontal unevenness due to the vibration generated when the cylindrical substrate is pulled up can be prevented.

The present invention has been completed based on the above findings, and its gist is to apply a coating solution of a photosensitive material on the outer peripheral surface of a cylindrical substrate by dip coating, and then dry it to form a cylinder. In a method for producing an electrophotographic photoreceptor in which a photosensitive coating film is formed on the surface of a cylindrical substrate, the cylindrical substrate is vertically lowered in a dipping tank in which the coating liquid overflows, and then immersed in the coating liquid. When the dip coating is carried out by vertically raising and pulling up the substrate, a cylindrical cylindrical tube of a size large enough to form a gap with the inner wall of the dipping tank without coming into contact with the outer periphery of the cylindrical substrate. Placed at a position around the entrance path of the cylindrical substrate, raising or lowering the cylindrical tube to block the surface of the coating liquid almost at the same time as the dipping operation of the cylindrical substrate, and immediately before or after the lifting operation of the cylindrical substrate. At the same time Consists in the method for producing a photoreceptor, characterized in that so as not to block the coating liquid surface is raised or lowered above cylindrical tube.

The present invention will be described in detail below. In the present invention, as the cylindrical substrate, various conventionally known ones can be used. For example, aluminum, brass, metal materials such as stainless steel, polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon,
Polymer materials such as polystyrene and phenol resin, or other materials such as hard paper can be molded into a cylindrical shape and used. In the case of an insulator material, it is necessary to conduct a conductive treatment, and the treatment method includes impregnation with a conductive substance,
Examples thereof include a method of laminating metal foil and vapor deposition of metal. The length of the cylindrical substrate is usually in the range of 30 to 100 cm.

As the coating liquid, various conventionally known ones composed of a photosensitive material and one or more kinds of solvents can be used.
For example, examples of the charge generating substance include azo pigments such as Sudan red, Diane blue, and Dienas green B, disazo pigments, quinone pigments such as algor yellow, pyrene quinone, quinocyanine pigments, perylene pigments, indigo pigments, and Indian Farst orange toners. Bisbenzimidazole pigments, phthalocyanine pigments such as copper phthalocyanine, quinacridone pigments, pyrylium salts, and azurenium salts.

As the charge-transporting substance, a polyaromatic compound such as anthracene, pyrene, phenanthrene, coronene or an indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, etc. in the main chain or side chain Examples thereof include compounds having a skeleton of nitrogen-containing cyclic compounds such as thiadiazole and triazole, and hole transporting substances such as hydrazone compounds.

As the binder resin for forming the photosensitive coating film, polycarbonate, polyarylate, polystyrene, polymethacrylic acid esters, styrene-methyl methacrylate copolymer, polyester, styrene-acrylonitrile copolymer, polysulfone, polyacetic acid, etc. Vinyl, polyacrylonitrile, polyvinyl butyral,
Examples thereof include polyvinylpyrrolidone, methyl cellulose, hydroxymethyl cellulose, cellulose esters and the like.

As the coating solvent, a solvent having a high volatility and a vapor density higher than that of air is preferably used. For example, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, N, N-dimethylformamide, acetone,
Methyl ethyl ketone, cyclohexanone, benzene, 4
-Methoxy-4-methylpentanone-2, dimethoxymethane, dimethoxyethane, 2,4-pentadione, anisole, methyl 3-oxobutanoate, monochlorobenzene, toluene, xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, Dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide,
Methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate and the like can be mentioned.

A coating solution of a photosensitive material for producing a single-layer type electrophotographic photosensitive material is prepared by mixing the above-mentioned charge generating substance, charge transporting substance, binder resin and coating solvent.
Further, the coating liquid of the photosensitive material in the case of manufacturing a laminated electrophotographic photosensitive member is a coating liquid for the charge generating layer consisting of the above charge generating substance, a binder resin and a coating solvent, and the above charge transporting substance. A coating solution for the charge transport layer, which comprises a binder resin and a coating solvent, is separately prepared.

The concentration of each component in the coating liquid is appropriately selected according to a known method. The concentration of the solid content is mainly determined according to the film thickness of the layer to be formed, but in the case of a coating solution for producing a single-layer type electrophotographic photosensitive member and for producing a laminated type electrophotographic photosensitive member. In the case of the coating liquid for the charge transport layer at the time of applying, it is 40% by weight or less, preferably 10 to 35%.
It is adjusted to be less than or equal to weight%. Further, in the case of these coating solutions, the viscosity thereof is 50 to 300 cps, preferably 70.
˜250 cps, and dry film thickness is preferably 15-40 μm.

In the present invention, in the dip coating, the cylindrical substrate is vertically lowered and immersed in the coating liquid in a dipping tank in which the coating liquid overflows, and then the cylindrical substrate is vertically raised and pulled up. By.

The greatest feature of the present invention is that a partition cylindrical tube having a size that can form a gap with the inner wall of the immersion tank without coming into contact with the outer periphery of the cylindrical base is provided around the entrance of the cylindrical base. At approximately the same time as the dipping operation of the cylindrical substrate, the cylindrical tube is raised or lowered to block the surface of the coating liquid, and the cylindrical tube is pulled immediately before or at the same time as the pulling operation of the cylindrical substrate. Is to raise or lower so as not to block the surface of the coating liquid.

1 to 3 are explanatory views of an example of the dip coating method which is preferably adopted in the present invention. The time series in these figures is shown in FIG. 1 (a) → FIG. 1 (b) → FIG. 2 (c).
→ FIG. 2 (d) → FIG. 3 (e) → FIG. 3 (f).

FIGS. 1 (a) and 1 (b) show a state before the cylindrical substrate (1) is immersed in the coating liquid (5). The coating liquid (5) is supplied from the coating liquid supply port (3) to the dipping tank (2) and overflows from the overflow section (6) of the dipping tank (2). The coating liquid overflowing into the overflow coating liquid receiving toy (4) is sent to the coating liquid tank (7), stirred, and then supplied again to the dipping tank (2) via the coating liquid supply pump (8). . Reference numeral (9) in the drawing denotes a hood provided on the dipping tank (2) and the overflow coating liquid receiving toy (4) as necessary to prevent evaporation of the solvent on the coating liquid surface.

The partition cylindrical tube (10) is a cylindrical substrate (1).
The cylindrical substrate (1) has a size such that a gap can be formed between the inner wall of the dipping tank (2) and the outer periphery of the cylindrical substrate (1).
It is located in the vicinity of the approach road. In the illustrated example, the partition cylindrical tube (10) is arranged in the upper part of the dipping tank (2), but it may be arranged by immersing the whole in the coating liquid. Before the cylindrical substrate (1) is dipped, the partition cylindrical tube (10) does not block the surface of the coating liquid. The coating liquid (5) is supplied from the coating liquid supply port (3) to the dipping tank (2) and overflows from the overflow section (6). Therefore, since the liquid on the surface of the coating liquid is constantly updated, sedimentation of the surface of the coating liquid is prevented.

First, in the present invention, the cylindrical substrate (1) is vertically lowered and immersed in the coating liquid in the dipping tank (2). At this time, substantially at the same time as the dipping operation of the cylindrical substrate (1), the partition cylindrical tube (10) is coated with the coating liquid (5) on its outer peripheral surface.
It is necessary to lower it to the position where it contacts the surface (Fig. 2
(C)). When the entire partition cylindrical tube (10) is immersed in the coating solution and arranged, the partition cylindrical tube (10) has its outer peripheral surface coated with the coating solution (at the same time as the cylindrical substrate (1) is dipped. 5) It is necessary to raise to the position where it comes into contact with the surface. "Simultaneously with the immersion operation of the cylindrical substrate (1)" refers to the range immediately before and immediately after the immersion operation of the cylindrical substrate (1). During the dipping operation of the cylindrical substrate (1), the upper end of the partition cylindrical tube (10) is located above the upper end of the dipping tank (2) and below the upper end of the dipping tank (1). Ten)
The partition cylindrical tube (10) is arranged such that the lower end of the partition tube is located (see FIGS. 2 (c) and 2 (d)).

According to the above operation, the coating liquid surface inside the partition cylindrical tube (10) is immersed between the overflow portion (6) and the cylindrical substrate (1) during the immersion of the cylindrical substrate (1). Since the surface is shielded by the partition cylindrical tube (10), the flow of the coating liquid along the surface of the cylindrical substrate (1) due to the overflow does not occur. As a result, flow unevenness does not occur on the surface of the cylindrical substrate (1). In addition, the partition cylindrical tube (1
On the inside of 0), the coating liquid is mixed due to the minute flow caused by the lowering of the cylindrical substrate (1), and as a result, no coating streak is generated on the surface of the cylindrical substrate.

The length of the partition cylindrical tube (10) above the upper end of the dipping tank (2) should be equal to or longer than the length of the meniscus formed on the wall of the partition cylindrical tube (10) by the surface tension of the coating liquid. Good. The length of the partition cylindrical tube (10) below the upper end of the dipping tank (2) is preferably 30 mm or more and 1/3 or less of the length of the cylindrical substrate (1).

Next, in the present invention, the cylindrical substrate (1) is vertically raised and pulled up while the coating liquid (5) overflows. The coating liquid (5) overflows to keep its liquid level constant, and as a result, the coating thickness of the coating liquid can be made constant by controlling only the rising speed of the cylindrical substrate (1). It can be applied with good properties. At this time, immediately before or at the same time as the pulling-up operation of the cylindrical substrate (1), it is necessary to raise the partitioning cylindrical tube (10) to a position where its outer peripheral surface separates from the surface of the coating liquid (5) (Fig. 3 (e) and (f)). When arranging the partition cylindrical tube (10) by immersing it in the coating liquid, the partition cylindrical tube (10) is lowered.

By the above-mentioned operation, the surface of the coating liquid is prevented from being blocked by the partitioning cylindrical tube (10) during the pulling up of the cylindrical substrate (1), and as a result, a minute disturbance due to the rise of the cylindrical substrate is applied. Vibration of the coating liquid surface around the cylindrical substrate can be prevented by being damped by the overflow of the liquid, and there is no horizontal unevenness on the surface of the cylindrical substrate. It should be noted that coating defects (flow irregularities) due to the overflow of the coating liquid hardly occur during the pulling operation of the cylindrical substrate.

In the present invention, when the laminated electrophotographic photosensitive member is produced, the above-mentioned specific dip coating method is enough to be applied to the coating solution for the charge generating layer, and the coating for the charge transporting layer. In the application of the liquid, for example, the conventional dip coating method shown in FIG. 4 may be adopted. After the dip coating, the coating film is formed by using a known drying means such as natural drying or hot air drying.

[0035]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 In this example, the dip coating method shown in FIGS. 1 to 3 was adopted. The immersion tank (2) has an inner diameter of 160 mm, the partition cylindrical tube (10) has a diameter of 130 mm, a length of 50 mm, and a wall thickness of 1
mm. The cylindrical substrate (1) has an outer diameter of 100 m
An aluminum tube having a length of m, a length of 340 mm, and a wall thickness of 1.5 mm is used, and the charge generation layer coating solution is described in JP-A-5-72760.
Azo pigment (charge-generating substance) 100 described in Example 1 of the publication No.
Parts by weight, polyvinyl butyral resin (binder) 10
0 parts by weight, solvent (dimethoxyethane / pentoxone = 9)
(1/1 weight ratio) 4800 parts by weight (solid content concentration 4% by weight).

First, the coating liquid (5) was allowed to overflow before the cylindrical substrate (1) was dipped. That is, the coating liquid (5) is supplied from the coating liquid supply port (3) to the dipping tank (2), overflows from the overflow section (6) of the dipping tank (2), and is supplied to the overflow coating liquid receiving toy (4). The overflowed coating liquid was sent to the coating liquid tank (7), stirred, and then supplied again to the dipping tank (2) via the coating liquid supply pump (8).

Next, the overflow of the coating liquid is stopped,
The cylindrical substrate (1) was lowered at a speed of 1500 mm / min. Separately from the cylindrical substrate (1), the partition cylindrical tube (10) is also lowered so that the lower end of the cylindrical substrate (1) contacts the surface of the coating liquid and at the same time the lower end of the partition cylindrical tube (10) contacts the coating liquid.
Then, it was immersed 40 mm from the liquid surface. Immersion of the cylindrical substrate (1) was performed at a speed of 1500 mm / min.

After the cylindrical substrate (1) was lowered to the immersion length, the immersion was stopped. Immediately thereafter, the partition cylindrical tube (1
0) was raised so as not to block the surface of the coating liquid, and the coating liquid was supplied to the dipping tank (2) from the coating liquid supply port (3) at a rate of 6 liters / minute. After the lower end of the partition cylindrical tube (10) was separated from the liquid surface, the cylindrical substrate (1) was pulled up at a rate of 500 mm / min while supplying the coating solution at a rate of 6 liters / minute, and the dry film thickness was reduced to 0. A 4 micron charge generation layer was formed. As a result of observing the obtained charge generation layer, it was a good coating film without coating defects such as coating streaks, flow unevenness and horizontal step unevenness.

Next, a charge transport layer was provided on the charge generation layer provided as described above by the same method as described above to obtain an electrophotographic photosensitive drum. The coating liquid for the charge transport layer contains 100 parts by weight of a hydrazone compound (charge transport substance), 100 parts by weight of a polycarbonate resin (binder), and a solvent (1,4-
Dioxane / tetrahydrofuran = 4/6 weight ratio) 46
It was prepared by 7 parts by weight (solid concentration 30% by weight).
The obtained electrophotographic photosensitive drum was attached to an actual copying machine and a real copying test was conducted. As a result, a good image without defects such as streaks and unevenness was obtained.

Comparative Example 1 As a result of carrying out the dip coating method in the same manner as in Example 1 except that the partition cylindrical tube (10) was not used,
Defects of flow unevenness on the entire surface of the cylindrical substrate (1) (see FIG. 5).
(B)) occurred.

Comparative Example 2 As a result of carrying out the dip coating method in the same manner as in Example 1 except that the partition cylindrical tube (10) was previously immersed in the coating liquid, the cylindrical substrate (1 5), a remarkable coating streak defect (FIG. 5 (a)) was produced.

Comparative Example 3 The same dip coating method as in Example 1 was carried out except that the partition cylindrical tube (10) was immersed in the coating liquid when the cylindrical substrate (1) was pulled up. As a result, defects of lateral unevenness (FIG. 5C) were generated on the entire surface of the cylindrical substrate (1).

[0044]

According to the present invention described above, the application stripe,
It is possible to manufacture an electrophotographic photosensitive member having a uniform photosensitive coating film without coating defects such as flow unevenness and horizontal unevenness.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of a dip coating method that is preferably adopted in the present invention.

FIG. 2 is an explanatory diagram of an example of a dip coating method that is preferably adopted in the present invention.

FIG. 3 is an explanatory diagram of an example of a dip coating method that is preferably adopted in the present invention.

FIG. 4 is an explanatory diagram of an example of a conventional dip coating method.

FIG. 5 is an explanatory diagram showing a form of coating defects of a photosensitive coating film.

[Explanation of symbols]

 1: Cylindrical substrate 2: Immersion tank 3: Coating liquid supply port 4: Overflow coating liquid receiving toy 5: Coating liquid 6: Overflow part 7: Coating liquid tank 8: Coating liquid supply pump 9: Hood 10: Partition cylindrical tube

Claims (1)

[Claims] 1. A method for producing an electrophotographic photosensitive member, comprising applying a coating solution of a photosensitive material material on the outer peripheral surface of a cylindrical substrate by dip coating, and then drying to form a photosensitive coating film on the surface of the cylindrical substrate. In the dipping tank in which the coating liquid overflows, the cylindrical substrate is vertically lowered and immersed in the coating liquid, and then the cylindrical substrate is vertically raised and pulled up to perform the dip coating described above. The partitioning cylindrical tube having a size capable of forming a gap with the inner wall of the dipping tank without coming into contact with the outer periphery of the cylindrical substrate is placed around the entrance path of the cylindrical substrate, and the dipping operation of the cylindrical substrate is performed. At about the same time, the cylindrical tube is raised or lowered to block the surface of the coating liquid,
A method for producing an electrophotographic photosensitive member, characterized in that the cylindrical tube is raised or lowered so as not to interrupt the surface of the coating liquid immediately before or at the same time as the raising operation of the cylindrical substrate.