JPH11226482A - Method for coating cylindrical substrate with paint and production of electrophotographic photoreceptor drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly transfer paint and to form a uniform coating film by making the paint thickness on the periphery of an applicator roller at the beginning of coating larger than the thickness of the paint film finally formed on a cylindrical substrate and then decreasing the paint thickness. SOLUTION: The gap width between a metering roller 3, for example, as a paint measuring means and an applicator roller 2 is set larger than the gap width between a cylindrical substrate 1 and the applicator roller 2 to form a paint layer on the periphery of the applicator roller 2, and then the transfer of the paint is started. Subsequently, the thickness of the paint film on the applicator roller 2 is decreased by decreasing the gap width between the metering roller 3 and applicator roller 2 to the width necessary to obtain the desired thickness of the film formed on the substrate 1. The excess paint is returned to the applicator roller 2 from the paint layer formed on the substrate 1 through a paint reservoir formed in the gap between the substrate 1 and applicator roller 2 and recovered in a paint tank 52.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a coating material to a cylindrical substrate suitable for a method for manufacturing a photosensitive drum for electrophotography.

[0002]

2. Description of the Related Art On an electrophotographic photosensitive drum, an undercoat layer, a charge generation layer, and a charge transport layer are sequentially applied and laminated as an electrophotographic photosensitive paint on the outer periphery of a hollow cylindrical substrate made of aluminum. Some of them form a photosensitive layer. The photosensitive layer is required to be a thin film and have a uniform thickness. However, since there is a strong demand for cost reduction, development and study of a coating method having excellent productivity are being conducted. As a method of forming a photosensitive layer by applying a photoreceptor paint for electrophotography to the outer periphery of a cylindrical substrate, a method such as a spray coating method, a dip coating method, or a blade coating method has been conventionally known. However, with the conventional coating method, a uniform coating film cannot be obtained,
There were drawbacks such as poor production efficiency.

For example, in the spray coating method, when a solvent having a low boiling point is used for the electrophotographic photoreceptor paint, the solvent contained in the paint volatilizes while the paint reaches the outer periphery of the cylindrical substrate, and the solid content concentration of the paint is reduced. However, when it reaches the cylindrical substrate, it does not spread sufficiently to the outer periphery, so that the surface of the coating film becomes uneven, so that the smoothness of the coating film surface cannot be obtained and a uniform coating film cannot be obtained. Was.

Conversely, when a solvent having a high boiling point is used, the coating material adheres to the outer periphery of the cylindrical substrate and leveling (uniform film thickness,
The same applies hereinafter), but fixation of the coating film is delayed due to slow evaporation of the solvent. Therefore, if the application is continued in a state where the coating is not sufficiently fixed, if the desired film thickness is large, paint dripping occurs, and a coating film having a uniform film thickness cannot be obtained. In order to avoid this, it is conceivable to apply the paint by dividing it into several times.However, it is conceivable to apply and dry the paint until it is dry to the touch (to the extent that no trace remains even when touched with a finger). Repeatedly to obtain the desired film thickness,
It was time-consuming and extremely complicated.

According to the dip coating method, the smoothness of the surface of the coating film is improved, but the coating film is formed inside or on the end surface of the cylindrical substrate. Since the coating film formed on the inside or the end face of the cylindrical base becomes an obstacle when attaching a flange or the like, when the cylindrical base is used as a photosensitive drum for electrophotography, the coating on the inside or the end face of the cylindrical base is required. Once formed, the coating must be peeled off. Further, depending on the model used, the coating film once formed on the outer peripheral end of the cylindrical substrate must be peeled off, which requires a peeling step, which is a factor that hinders productivity.

Further, the thickness of the coating film is largely controlled by the physical properties of the coating material and the pulling speed after immersion. When the coating film is pulled at a constant speed, a difference in film thickness occurs between the upper end and the lower end of the cylindrical substrate. In order to solve this, it is necessary to control the pulling speed, but it is difficult to control it, and furthermore, it is necessary to slow down the pulling speed after immersion in order to form a uniform coating film. There was a problem, and high production efficiency could not be obtained.

[0007] The blade coating method is a coating method in which a blade is arranged at a position close to the longitudinal direction of a cylindrical substrate, paint is supplied to the blade, the cylindrical substrate is rotated once, and then the blade is retracted. Although high productivity can be obtained by this method, when the blade is retracted, there is a disadvantage that the coating applied to the cylindrical substrate partially rises due to the surface tension of the coating, so that the film thickness becomes uneven.

[0008] Furthermore, there is a roll coating method as a method other than the above method. The roll coating method is special in that the object to be coated is a cylindrical substrate, that is, the coating is performed once by rotating the cylindrical substrate as the object to be coated. The returned surface repeatedly returns to the application section, causing a problem that a paint pool is generated and the film thickness becomes non-uniform.

In order to avoid the occurrence of this paint pool,
For example, in Japanese Patent Application Laid-Open No. Hei 3-12261, when the cylindrical substrate makes one rotation and the coating is applied to the entire outer periphery thereof,
It has been proposed to separate the cylindrical substrate from the paint application roll. However, this requires rather complicated and precise control, and if the cylindrical substrate is rotated once, the problem before obtaining a uniform coating is that the entire area where the coating is to be applied must be coated. Was not applied. In other words, it takes a considerable time to complete the transfer of the paint from the paint application roll to the entire surface of the cylindrical substrate, which is one factor that hinders an improvement in productivity.

[0010] Further, in the same publication, after the coating is completed by rotating the drum one or more rotations, the drum is separated from the paint supply roll, and the drum is continuously rotated to level the coating film surface (uniform film thickness). However, in this method, precise film thickness control must be performed in anticipation of the amount of paint pool to be leveled in advance.

Japanese Patent Application Laid-Open No. 2-222743 also discloses that a coating film formed on the peripheral surface of a coating roller is transferred (transferred) only to the peripheral surface of a cylindrical substrate to be coated. Although a method of breaking the contact of the application roll is disclosed, complicated and precise control is required as described above.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional coating method, and in the roll coating method, the paint can be quickly transferred from the paint applying roll to the entire surface of the cylindrical substrate. Another object of the present invention is to provide a method for forming a uniform coating film on the outer periphery of a cylindrical substrate with a simple control.

[0013]

Means for Solving the Problems The present inventors have intensively studied the roll coating method in view of the above-mentioned situation, and found that in order to rapidly transfer the paint from the paint application roll to the entire surface of the cylindrical substrate, It has been found that it is effective to apply a larger amount of paint than the amount that should be applied to the cylindrical substrate at the beginning of the transfer.

The present invention is based on the above findings,
In the method of applying the coating material supplied to the application roll to the cylindrical substrate, the coating film thickness on the outer periphery of the application roll at the beginning of application is determined by the coating film thickness finally formed on the cylindrical substrate. Thicker than that, and then the paint film thickness is reduced.

In order to form a coating film having a uniform thickness on the cylindrical substrate, the present inventor has to rotate the cylindrical substrate and the coating roll in the same direction, It has been found that it is effective to make the film thickness uniform. Therefore, in addition to the above-described present invention, the coating is performed while rotating the cylindrical substrate and the coating roll in the same direction, and after the coating film thickness is further reduced, the film thickness is uniformly controlled, whereby the cylindrical shape is formed. The uniformity of the coating film formed on the substrate can be improved.

In the present invention, the coating film thickness on the outer periphery of the application roll may be controlled by a coating material measuring means composed of a columnar member having a cylindrical, plate-like, or elliptical section in cross-sectional shape. Then, in order to make the thickness of the paint on the outer periphery of the coating roll at the beginning of the application using the paint measuring means larger than the thickness of the paint finally formed on the cylindrical substrate, the paint measuring means should be used at the beginning of the application. And the gap width between the coating roll and the coating roll may be set wider than the gap width between the cylindrical substrate and the coating roll. Assuming that the gap width between the paint measuring means and the application roll is G1, and the gap width G2 between the cylindrical substrate and the application roll is G1, it is preferable that G1 ≧ 1.5G2.

Hereinafter, the method for coating a cylindrical substrate according to the present invention will be described in detail. First, the reason why the cylindrical substrate and the application roll (hereinafter, referred to as an applicator roll) are rotated in the same direction in the present invention will be described with reference to FIGS.

8 and 9, reference numeral 1 denotes a cylindrical substrate as an object to be coated, and 2 denotes an applicator roll, each of which rotates in the direction of an arrow (solid line). That is, FIG. 8 shows a case where the cylindrical base 1 and the applicator roll 2 rotate in the same direction, and FIG. 9 shows a case where the cylindrical base 1 and the applicator roll 2 rotate in the opposite directions. I have. The coating material 5 is affected by the rotation direction of the cylindrical substrate 1 and the applicator roll 2, and flows in the directions of the arrows (chain lines).

As shown in FIG. 9, when the cylindrical substrate 1 and the applicator roll 2 rotate in opposite directions, the paint 5 applied to the cylindrical substrate 1 at the transition starting point 91 passes through the transition end point 92. It returns to the transition starting point 91 with the rotation of the cylindrical substrate 1. Therefore, a part of the paint 5 successively supplied by the applicator roll 2 cannot pass through the gap between the cylindrical substrate 1 and the applicator roll 2. The paint 5 that cannot pass is accumulated near the transition starting point 91 and forms a paint pool 8. When the cylindrical substrate 1 is separated from the applicator roll 2 in this state, a portion corresponding to the paint pool 8 protrudes and impairs the uniformity of the coating film. It is conceivable to separate the cylindrical substrate 1 from the applicator roll 2 before the paint pool 8 is formed, but in such a case, it is impossible to uniformly apply the coating to the outer periphery of the cylindrical substrate 1.

On the other hand, when the rotation direction of the cylindrical base 1 and the applicator roll 2 is set to the same direction as shown in FIG. In other words, most of the paint conveyed by the applicator roll 2 reaches the transfer end point 92 from the arrow (chain line) transfer start point 91 along with the rotation of the cylindrical base 1 via the outer periphery of the cylindrical base 1. Therefore, even if the paint continues to be transferred from the applicator roll 2 to the cylindrical substrate 1, the paint pool 8 does not occur at the transfer start point 91. Even if it occurs, the amount is small, and can be eliminated to such an extent that there is no functional hindrance by leveling after the cylindrical substrate 1 is separated from the applicator roll 2.

By setting the rotation direction of the cylindrical substrate 1 and the applicator roll 2 in the same direction, the occurrence of paint accumulation can be prevented or suppressed, but the uniformity of the coating film formed on the outer periphery of the cylindrical substrate 1 can be quickly improved. It is important to make the coating supplied to the applicator roll 2 uniform in film thickness. That is, it is extremely difficult to form a uniform coating film on the outer circumference of the cylindrical substrate 1 only by one rotation after the cylindrical substrate 1 starts to contact the paint on the outer periphery of the applicator roll 2. Rotation is required. However, since the number of rotations affects the production efficiency, it is desirable to form a coating film having a uniform film thickness at the lowest possible number of rotations. In order to form a coating film having a uniform thickness on the outer periphery of the cylindrical substrate 1 at a lower rotation speed, it is effective to make the thickness of the coating film on the outer periphery of the applicator roll 2 uniform. A method for making the thickness of the coating film on the outer periphery of the applicator roll 2 uniform will be described later. It is difficult to quickly form a proper coating film.

Next, the reason why the coating film thickness on the outer periphery of the coating roll at the beginning of the coating is made larger than the coating film thickness finally formed on the cylindrical substrate will be described. The thickness of the coating film on the outer periphery of the applicator roll 2 is uniform, and this thickness is
In principle, if the gap is equal to the gap between the roller and the applicator roll 2, the paint should transfer quickly over the entire width of the cylindrical substrate 1 in the axial direction. However, the gap is not uniform in the axial direction because both the cylindrical base 1 and the applicator roll 2 have a certain degree of mechanical precision dimensional error. That is, there is actually a portion wider or narrower than the set gap.

Therefore, even if a film thickness corresponding to the set gap is formed on the outer periphery of the coating roll, the transfer of the paint does not occur immediately in the portion where the gap is wider than the set gap, and the transfer from other portions does not occur. As it occurs, it gradually progresses to another part, that is, a region corresponding to a part wider than the set gap, and finally undergoes a process in which the metastasis survives over the entire width.

In order to shorten this process as much as possible,
In practice, an amount of paint corresponding to a gap portion that is actually wider than the set gap may be supplied from the beginning. Therefore, in the present invention, the coating film thickness on the outer periphery of the coating roll at the beginning of the coating is made thicker than the coating film thickness finally formed on the cylindrical substrate, so that the coating film can be quickly moved from the applicator roll to the entire width of the cylindrical substrate in the axial direction. Enables paint transfer. After the transfer of the paint over the entire width of the cylindrical substrate in the axial direction, the paint film thickness on the applicator roll is adjusted to the desired film thickness to be applied to the cylindrical substrate. Here, surplus paint supplied to the cylindrical substrate at the beginning of the application is returned to the applicator roll through a paint reservoir formed between the cylindrical substrate and the applicator roll. Therefore, a coating film having a desired thickness can be formed on the cylindrical substrate.

The ease with which the paint is transferred from the applicator roll to the cylindrical substrate is greatly affected by the viscosity of the paint. If the paint viscosity is high, the transfer is unlikely to occur. Is less likely to occur. Therefore, how thick the coating film thickness on the outer periphery of the coating roll at the beginning of coating should be larger than the coating film thickness finally formed on the cylindrical substrate should be appropriately determined in consideration of these factors. . In the present invention, the beginning of the application of the paint is defined as the start of the transfer of the paint from the applicator roll to the cylindrical substrate, but the end is not specifically specified. This is because the ease of transfer varies depending on conditions such as the paint viscosity and the rotation speed of the cylindrical substrate.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. 1 and 2 are a perspective view and a side view, respectively, showing the structure of an apparatus for carrying out an embodiment of the method of the present invention.
1 and 2, reference numeral 1 denotes a cylindrical substrate which is an object to be coated;
2 is an applicator roll (application roll), 3 is a metering roll (paint measurement means), 4 is a cleaning doctor,
5 is a paint, 9 is a driving device for adjusting a metering roll gap, and 52 is a paint tank.

The cylindrical base 1, the applicator roll 2, and the metering roll 3 are installed so as to be rotatable in the direction of the arrow by a rotating mechanism (not shown). Further, the cylindrical substrate 1
The applicator roll 2 and the applicator roll 2 are disposed close to each other with a gap capable of transferring the paint from the applicator roll 2 to the cylindrical substrate 1, and the metering roll 3 is engaged with the cleaning blade 4 by an engaging mechanism (not shown). The applicator roll 2, which is connected to the ring roll gap adjusting drive device 9 and is partially immersed in the paint 5 in the paint tank 52, and the extent to which the paint can transfer from the applicator roll 2 to the cylindrical substrate 1. Are arranged close to each other with a gap equal to or larger than that.

The applicator roll 2, which is partially immersed in the paint 5 in the paint tank 52, is rotated in the direction of the arrow, and the paint 5 which has been scraped up is rotated with the applicator roll 2 in the direction of the arrow. The paint 5 is supplied to the outer periphery of the applicator roll 2 through the gap with the metering roll 3, and the paint 5 supplied to the applicator roll 2 is measured by passing through the gap having a certain width. Excess paint 5 scraped off by the metalling roll 3 is completely scraped off by the cleaning blade 4 as the metalling roll 3 rotates, and returns to the paint tank 52 again. By rotating the applicator roll 2 and the metering roll 3 in the direction of the arrow in this state, the film thickness of the coating material 5 on the outer periphery of the applicator roll 2 becomes uniform. The film thickness also quickly becomes uniform. In the above embodiment, the metering roll 3 is rotated, but may be fixed without rotating.

In the above embodiment, the metering roll 3
The paint 5 on the outer periphery of the applicator roll 2
The thickness of the paint tank 5 is made uniform as shown in FIG.
The applicator roll 2 is immersed in the paint 5 stored in the apparatus 2 and a gap setting doctor 6 connected with a gap adjusting drive device 91 as a paint measuring means for supplying a predetermined amount of paint is supplied with a gap having a predetermined width. It may be arranged on the applicator roll 2 through the intermediary. By rotating the applicator roll 2 in this state, the thickness of the coating material 5 on the outer periphery of the applicator roll 2 is made uniform.

Further, as shown in FIG. 4, a plate-shaped paint measuring means 61 connected to a gap adjusting drive device 92 is arranged in a tangential direction of the applicator roll 2 with a gap having a predetermined width, or as shown in FIG. A paint metering means 62 having a step on the outer periphery of a cylindrical body to which a gap adjusting drive device 93 is connected as shown in FIG. 6 is disposed between the applicator roll 2 and a gap having a predetermined width. The column-shaped paint measuring means 63 having an elliptical section in cross-sectional shape to which the adjusting drive device 94 is connected may be arranged with the applicator roll 2 via a gap having a predetermined width. Paint measuring means 61, 6 shown in FIGS.
According to 2, 63, the uniformity of the film thickness of the coating material 5 can be improved more than the gap setting doctor 6 shown in FIG.

As another method, as shown in FIG. 7, a pickup roll 7 is placed in a paint 5 stored in a paint tank 52.
The coating 5 transferred from the pickup roll 7 to the applicator roll 2 is transferred to the applicator roll 2 and the metalling roll 3 connected to the metalling roll gap adjusting drive 95 disposed close to the applicator roll 2. There is also a method of metering and supplying at the gap between the two. In this case, the cleaning doctor 4 is installed on the metering roll 3,
Excess paint 5 can be returned to the paint tank 52. In this state, by rotating the applicator roll 2, the metering roll 3, and the pickup roll 7 in the direction of the arrow,
The thickness of the paint on the outer periphery of the applicator roll 2 is made uniform.

In any of the above-described embodiments, the transfer of the coating layer formed on the outer periphery of the applicator roll 2 to the cylindrical substrate 1 quickly and reliably reduces the coating time and reduces defective products. It is very important not to get out. If the gap between the cylindrical substrate 1 and the applicator roll 2 is equal to the thickness of the paint layer formed on the outer periphery of the applicator roll 2, the transfer of the paint to the entire width of the cylindrical substrate 1 should occur quickly. As described above, the transfer of the paint does not progress simultaneously in the axial direction of the cylindrical substrate 1, but is partially transferred, gradually spread to other parts, and finally the paint spreads over the entire width. Pass. In addition, the paint transfer from the applicator roll 2 to the cylindrical substrate 1 is greatly affected by the paint viscosity, and the transfer becomes difficult as the paint viscosity increases. However, if the number of rotations is high, the transfer of the paint is unlikely to occur.

In order to solve this problem, the gap width between the paint metering means and the applicator roll 2 should be at least 1.5 times the gap width between the cylindrical substrate 1 and the applicator roll 2, preferably 1. 7 times or more, more preferably 2.0 times
A paint layer is formed on the outer periphery of the applicator roll 2 in a state where the paint is set to twice or more, and the transfer of the paint is started. The transfer of the paint is quickly performed over the entire width of the cylindrical substrate 1 in the axial direction. Thereafter, the thickness of the paint film on the outer periphery of the applicator roll 2 is reduced to the width necessary to obtain a desired film thickness to be applied on the outer periphery of the cylindrical substrate 1 by the gap width between the paint measuring means and the applicator roll 2. By doing so, excess paint returns to the applicator roll 2 from the paint layer formed on the cylindrical base 1 through a paint pool (meniscus portion) formed in the gap between the cylindrical base 1 and the applicator roll 2. ,
Collected in the paint tank 52.

When the metering roll 3 is used as the paint measuring means, the coating film thickness can be controlled by increasing or decreasing the number of rotations of the metering roll 3 in addition to increasing or decreasing the gap width with the applicator roll 2. can do.

The gap between the cylindrical substrate 1 and the applicator roll 2 is determined by adjusting the wet film thickness (the film thickness after drying) formed on the cylindrical substrate 1 and the solid content ratio of the paint. (The film thickness before drying) or more, and the gap between the paint measuring means and the applicator roll 2 is initially set to 1.5 times the gap between the cylindrical substrate 1 and the applicator roll 2.
A coating film is formed on the applicator roll 2 at twice or more, preferably twice or more, so that the paint is transferred to the cylindrical substrate 1 quickly over the entire width of the cylindrical substrate 1. Then, the gap width between the paint measuring means and the applicator roll 2 is reduced to a width necessary for obtaining a desired thickness of the paint film on the applicator roll 2 to be applied on the cylindrical substrate 1. As a result, excess paint returns from the coating film formed on the cylindrical substrate 1 to the applicator roll 2 through a paint pool (meniscus portion) formed between the cylindrical substrate 1 and the applicator roll 2, and The paint in the meniscus is also reduced. When the cylindrical substrate 1 is separated from the applicator roll 2, the paint on the meniscus portion remaining on the cylindrical substrate 1 side is scarcely or considerably reduced. If leveling is performed thereafter, a coating film having a uniform film thickness can be obtained quickly.

The roll diameter of the applicator roll 2 is preferably in the range of 1/4 to 10 times the diameter of the cylindrical substrate 1.

When the cylindrical substrate 1 and the applicator roll 2 are close to each other, it means that they are in contact with each other via the paint.
The specific gap width is 10 μm to 10 μm depending on the type of coating material to be applied and the film thickness finally formed on the cylindrical substrate 1.
It may be set to a value within the range of 00 μm and equal to or less than the gap width between the applicator roll 2 and the paint measuring means. Further, the gap width between the applicator roll 2 and the paint measuring means is also 10 μm to 10 μm depending on the kind of paint to be applied and the film thickness finally formed on the cylindrical substrate 1.
What is necessary is just to set in the range of 00 micrometers. Note that the above gap width is within the range of the present invention, that is, the condition that the paint film thickness around the applicator roll at the beginning of paint application is larger than the paint film thickness finally formed on the cylindrical substrate. Needless to say, it must be set.

The peripheral speed of rotation of the cylindrical substrate 1 when the coating material is applied should be in the range of 3 m / min to 50 m / min, and the peripheral speed of rotation of the applicator roll 2 should be 3 m / min.
It is preferable to set the range of min to 50 m / min.
If the peripheral speed of the cylindrical substrate 1 and the applicator roll 2 is low, the uniformity of the coating film formed on the outer periphery is insufficient, and it takes a long time until the coating film is formed on the outer periphery of the cylindrical substrate 1, Conversely, if the peripheral speed is too high, the paint may be scattered by the centrifugal force.

The ratio of the peripheral speed of rotation of the cylindrical substrate 1 to the peripheral speed of rotation of the applicator roll 2 (the peripheral speed of the cylindrical substrate / the peripheral speed of the applicator roll) is in the range of 0.5 to 2.0. Is preferable, and the range of 0.6 to 1.5 is more preferable.

In the coating method of the present invention, it is not preferable to apply one layer of paint to the outer periphery of the cylindrical substrate 1, in other words, to separate from the applicator roll 2 when the cylindrical substrate 1 makes one rotation. That is, even if the present invention is applied, the transfer of the paint from the applicator roll 2 to the cylindrical substrate 1 is performed over the entire width of the cylindrical substrate 1 when the cylindrical substrate 1 makes one rotation, and the coating with a uniform film thickness is performed. This is because it is difficult to obtain a film, and the coating film is uniformly formed on the outer periphery of the cylindrical substrate 1 only after the cylindrical substrate 1 rotates several times. Therefore, the cylindrical substrate 1 is separated from the applicator roll 2 after the cylindrical substrate 1 has been rotated at least several times to form a uniform coating film with a desired film thickness.

After the cylindrical substrate 1 is separated from the applicator roll 2, the rotation of the cylindrical substrate 1 is continued by leveling and drying the formed coating film, and the coating film is fixed even if the rotation is stopped. After the state where the sagging does not occur,
It may be placed in a hot-air circulation dryer and dried completely.

When a solvent having a relatively high volatility is used, a container or a shielding wall in which the applicator roll portion, the cylindrical base portion or the entire periphery thereof is substantially sealed to prevent drying due to the volatilization of the solvent. It is also effective to cover with such as.

Examples of the material of the cylindrical substrate include metals such as aluminum, iron, copper, manganese, silicon, magnesium, zinc, stainless steel, chromium, titanium, nickel, molybdenum, vanadium, indium, gold, platinum and the like. Examples thereof include a material in which a conductive material such as aluminum is vapor-deposited on a resin such as an alloy or polyester, but the present invention is not limited to these materials.

When the cylindrical substrate is a photosensitive drum for electrophotography, the photosensitive layer to be formed is a single layer type in which the charge generating material and the charge transporting material are present in the same layer. It may be a stacked type in which a layer containing a charge generation material and a layer containing a charge transport material are stacked.

The single-layer type photosensitive layer can be formed by applying a coating solution in which a charge generating material and a charge transporting material are dispersed or dissolved in a binder resin solution to the outer periphery of a cylindrical substrate and then drying.

The laminate type photosensitive layer is formed by applying a coating material in which fine particles of a charge generating material are dispersed in a binder resin solution as needed to the outer periphery of a cylindrical substrate and then drying to form a charge generating layer.
It can be obtained by forming a charge transport layer by applying a coating material in which a compound having a charge transport function is dissolved in a binder resin solution and then drying it. Conversely, the charge generation layer may be formed after forming the charge transport layer on the outer periphery of the cylindrical substrate.

The layer thickness of the photosensitive layer in the electrophotographic photosensitive member is 5 to 50 μm in the case of a single-layer type electrophotographic photosensitive member.
Is preferable, and the range of 15 to 40 μm is particularly preferable.

In the case of a laminated electrophotographic photosensitive member, the thickness of the charge generation layer is preferably 5 μm or less.
The range of 01 to 1 μm is particularly preferred, and the thickness of the charge transport layer is preferably in the range of 5 to 50 μm, and particularly preferably in the range of 15 to 40 μm.

Examples of the charge generating material include phthalocyanine pigments, azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, quinacridone pigments, quinoline pigments, lakes Pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, azurenium dyes, squarium dyes, pyrylium dyes, triallylmethane dyes, xanthene dyes, thiazine dyes, cyanine dyes, etc. Examples include various organic pigments and dyes, and inorganic materials such as amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide.

The charge-generating substance is not limited to those listed here.
More than one kind can be mixed and used. In the case of a charge generation layer formed by applying a dispersion liquid in which fine particles of the charge generation material are dispersed in a binder resin solution as needed, and drying the dispersion,
The use ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by weight, and 6: 1 to 1: 1.
A range of 2 is more preferred.

As the charge transporting material, a hole transporting material and / or an electron transporting material can be used. Examples of the hole transport material include low molecular weight compounds such as pyrene, carbazole, hydrazone, oxazole, oxadiazole, pyrazoline, arylamine, arylmethane, benzidine, thiazole, and stilbene. And butadiene compounds. Examples of the polymer compound include poly-N-vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl anthracene, polyvinyl acridine, pyrene-formaldehyde resin, ethyl carbazole-formaldehyde resin, and ethyl carbazole. Formaldehyde resin, triphenylmethane polymer, polysilane and the like can be mentioned.

Examples of the electron transporting material include organic compounds such as benzoquinone, tetracyanoethylene, tetracyanoquinodimethane, fluorenone, xanthone, phenanthraquinone, phthalic anhydride and diphenoquinone. , Amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide,
Examples include inorganic materials such as antimony sulfide, zinc oxide, and zinc sulfide. The charge transporting material is not limited to those listed here, and can be used alone or as a mixture of two or more.

As the binder resin, it is preferable to use a high molecular polymer which is hydrophobic and can form an electrically insulating film. As such a high-molecular polymer, for example,
Polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetic acid Vinyl-maleic anhydride copolymer, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinyl butyral, polyvinyl formal, polysulfone, and the like. It is not limited. These binder resins are used alone or in combination of two or more. Further, additives such as a plasticizer, a sensitizer, and a surface modifier can be used together with these binder resins.

Examples of the plasticizer include biphenyl, biphenyl chloride, o-terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenylphosphoric acid, methylnaphthalene, benzophenone, and chlorinated paraffin.

Examples of the sensitizer include chloranil, tetracyanoethylene, methyl violet, rhodamine B, cyanine dye, merocyanine dye, pyrylium dye, and thiapyrylium dye.

Examples of the surface modifier include silicone oil, fluororesin and the like. In order to improve the adhesiveness between the cylindrical substrate and the photosensitive layer and to prevent the injection of free charges from the cylindrical substrate to the photosensitive layer, an adhesive layer may be interposed between the cylindrical substrate and the photosensitive layer, if necessary. Alternatively, a barrier layer (undercoat layer) can be provided.

Materials used for these layers include, in addition to the polymer compound used for the binder, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, polyimide, carboxy-methyl cellulose, vinylidene chloride-based polymer latex, Polyurethane, aluminum oxide, tin oxide,
Titanium oxide and the like can be mentioned.

The substance imparting the function as an adhesive or a barrier is not limited to those listed here.
When used, they can be used alone or as a mixture of two or more.

When the adhesive layer or the barrier layer is provided, the thickness is preferably from 0.005 μm to 12 μm, and more preferably from 0.01 μm to 2 μm.

When the above-mentioned charge generating material and charge transporting material are dispersed and dissolved in a binder resin solution, the solvent for dissolving the binder resin does not dissolve the underlying layer, although it depends on the type of the binder resin. Consider choosing from among things.

Specific examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol and benzyl alcohol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, isophorone and acetylacetone; N, N-dimethylformamide; , N
Amides such as dimethylacetamide; ethers such as tetrahydrofuran, dioxane, methyl cellosolve, and diglyme; esters such as methyl acetate, ethyl acetate, and diethyl carbonate; sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; methylene chloride, chloroform; Aliphatic halogenated hydrocarbons such as carbon tetrachloride, 1,1,2-trichloroethane; benzene, toluene, o-
Examples include, but are not limited to, aromatics such as xylene, p-xylene, m-xylene, monochlorobenzene, and dichlorobenzene. These solvents are used alone or in combination of two or more.

[0062]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the scope of these examples.

(Example 1) An applicator roll 2 made of carbon steel having a surface roughness of 3.2 S, a length of 260 mm, and an outer diameter of 65 mm, and a driving device 9 for adjusting a metering roll gap are provided. And a cylindrical substrate 1 as an object to be coated.
And were arranged as shown in FIG. A cleaning doctor 4 made of resin was disposed on the metering roll 3 as shown in FIG. The cylindrical substrate 1 is made of aluminum and has a length of 2
It has a hollow structure of 54 mm, outer diameter 30 mm and wall thickness 1 mm. For the purpose of obtaining a photosensitive drum for electrophotography, an undercoating paint was first applied to the cylindrical substrate 1.

The coating for the undercoat layer is prepared by dissolving 3.5 parts of soluble nylon (“CM-8000” manufactured by Toray Industries, Inc.) in a mixed solvent consisting of 57.9 parts of ethanol and 38.6 parts of benzyl alcohol. did.

Both ends of the cylindrical substrate 1 are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. This gripping mechanism is mounted on a moving device (not shown) that can approach and separate from the applicator roll 2. Although the cylindrical substrate 1 and the applicator roll 2 are initially separated, the moving device is set so that the gap width is 50 μm during coating. The gap width between the applicator roll 2 and the metering roll 3 was initially set to 100 μm.

The rotation directions of the cylindrical substrate 1 and the applicator roll 2 are the same, and the rotation directions of the applicator roll 2 and the metering roll 3 are also the same. The peripheral speed is
The cylindrical substrate was set to 20 m / min, the applicator roll was set to 20 m / min, and the metering roll was set to 2 m / min. .

After the applicator roll 2 and the metering roll 3 are rotated, the coating tank 5 containing the coating 5 for the undercoat layer is formed.
2 is lifted by a lifting device (not shown), so that the lower portion of the applicator roll 2 is immersed,
A coating film was formed on the outer periphery of.

Thereafter, the coating was started by rotating the cylindrical substrate 1 while approaching the applicator roll 2 until the gap width described above was reached. This allows applicator roll 2
The above paint was instantaneously transferred over the entire width of the cylindrical substrate 1. One second after the start of coating, the gap between the metalling roll 3 and the applicator roll 2 is narrowed from the initial 100 μm to 25 μm by the metalling roll gap adjusting device 9 connected to the metalling roll, and the rotating state is maintained for 3 seconds. After that, the cylindrical substrate 1 was separated from the applicator roll 2.

The cylindrical substrate 1 on which the undercoat layer was applied was air-dried while rotating it for 3 minutes, and then dried at 120 ° C. for 5 minutes using a hot-air circulation dryer.

The film thickness after drying was measured by a spectral reflection interference film thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 0.9 μm.

(Example 2) The coating apparatus used in Example 1 was used for the cylindrical substrate 1 having an undercoat layer applied to the outer periphery in Example 1 (hereinafter referred to as the undercoat layer-coated cylindrical substrate 1). hand,
A charge generation layer was applied.

The coating material for the charge generating layer was composed of 0.8 parts of α-oxytitanium phthalocyanine and 0.8 parts of butyral resin (“ESLEK BH-3” manufactured by Sekisui Chemical Co., Ltd.), 49.25 parts of isopropyl alcohol and cyclohexanone. It was added to a mixed solvent consisting of 49.25 parts, and the average particle size was 1.
It was prepared by dispersing and mixing with 0 mm glass beads.

The undercoat layer-coated cylindrical substrate 1 to be coated is
As in the first embodiment, both ends are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. This gripping mechanism is mounted on a moving device (not shown) that can approach and separate from the applicator roll 2.

The undercoat layer-coating cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, but the moving device is set so that the gap width is 40 μm at the time of coating. The applicator roll 2 and the metering roll 3
Was initially set to 80 μm.

The rotation directions of the undercoat layer-coated cylindrical substrate 1 and the applicator roll 2 are the same, and the rotation directions of the applicator roll 2 and the metering roll 3 are also the same. The peripheral speed of the undercoat layer-coated cylindrical substrate 1 was 11.2.
m / min, applicator roll 2 is 10.1 m / mi
n, the metering roll is 2 m / min.

After the applicator roll 2 and the metering roll 3 are rotated, the paint tank 52 containing the charge generating layer paint 5 is raised by a lifting device (not shown), and the lower part of the applicator roll 2 is immersed. Then, a coating film having a uniform thickness was formed on the outer periphery of the applicator roll 2.

Thereafter, the coating was started by rotating the cylindrical substrate 1 for applying the undercoat layer while approaching the applicator roll 2 until the gap width described above was reached. As a result, the paint on the applicator roll 2 was instantaneously transferred over the entire width of the cylindrical substrate 1 coated with the undercoat layer. One second after the start of coating, the gap between the metalling roll 3 and the applicator roll 2 is reduced from the initial 80 μm to 20 μm by the metalling roll gap adjusting device 9 connected to the metalling roll, and then the rotary state is maintained for 3 seconds. Was maintained, the undercoat layer-coated cylindrical substrate 1 was separated from the applicator roll 2.

The undercoat layer-coated cylindrical substrate 1 coated with the charge generating layer was air-dried while being rotated for 3 minutes as it was, and then dried at 120 ° C. for 5 minutes by a hot-air circulation dryer.

The film thickness after drying was measured by a spectral reflection interference film thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 0.2 μm.

(Example 3) The coating apparatus used in Example 1 was applied to the cylindrical substrate 1 having the charge generation layer applied to the outer periphery in Example 2 (hereinafter referred to as the charge generation layer coated cylindrical substrate 1). Thus, a charge transport layer was applied.

The coating material for the charge transport layer is composed of 20 parts of an arylamine compound represented by the chemical formula (1) and a polycarbonate resin ("Iupilon Z-20" manufactured by Mitsubishi Gas Chemical Company, Inc.).
0 ") was prepared by dissolving 25 parts in a mixed solvent consisting of 58 parts of cyclohexanone and 58 parts of xylene.

[0082]

Embedded image

The charge generating layer-coated cylindrical substrate 1 was prepared in Example 1.
Similarly, both ends are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. This gripping mechanism is installed in a moving device (not shown) that can approach and separate from the applicator roll 2.

The charge generating layer coating cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, but the moving device is set so that the gap width is 180 μm at the time of coating. The gap width between the applicator roll 2 and the metering roll 3 was initially set to 420 μm.

The rotation direction of the charge generating layer-coated cylindrical substrate 1 and the applicator roll 2 is the same, and the peripheral speed of rotation is 10.2 m / min for the charge generating layer-coated cylindrical substrate 1 and 10. 2 m / min, and the metering roll is 1.0 m / min.

After the applicator roll 2 and the metering roll 3 are rotated, the paint tank 52 containing the charge generating layer paint 5 is raised by a lifting device (not shown) so that the lower portion of the applicator roll 2 is immersed. A coating film was formed on the outer periphery of the applicator roll 2.

Thereafter, while rotating the cylindrical substrate 1 for applying the charge generation layer, the application was started by approaching the applicator roll 2 until the gap width described above was reached. As a result, the coating material on the applicator roll 2 is applied to the cylindrical substrate 1 coated with the charge generating layer.
Transferred within 0.5 seconds over the entire width of. Two seconds after the start of the application, the gap between the metalling roll 3 and the applicator roll 2 is reduced from the initial 420 μm to 100 μm by the metalling roll gap adjusting device 9 connected to the metalling roll, and the rotating state is maintained for 3 seconds. After that, the cylindrical substrate 1 was separated from the applicator roll 2.

The charge generating layer-coated cylindrical substrate 1 coated with the charge transporting layer was air-dried while being rotated for 12 minutes, and then dried at 120 ° C. for 60 minutes by a hot-air circulation dryer.

The film thickness after drying was measured by a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 25.2 μm. FIG. 10 shows the axial thickness distribution, and FIG. 11 shows the circumferential thickness distribution.
As shown.

A printing test was carried out one day after the production using the electrophotographic photosensitive drum obtained as described above, and the image characteristics were good.

Example 4 In applying the charge transport layer coating material used in Example 3 to the charge generating layer coating cylindrical substrate 1 obtained in Example 2, the coating apparatus shown in FIG. 5 was used. And a charge transport layer.

The charge-generating layer-coated cylindrical substrate 1 was prepared in Example 1.
Similarly, both ends are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. This gripping mechanism is installed in a moving device (not shown) that can approach and separate from the applicator roll 2.

The charge generating layer coating cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, but the moving device is set so that the gap width is 180 μm at the time of coating. The gap width between the applicator roll 2 and the gap setting doctor (comma doctor) 62 was initially set to 400 μm.

The rotation direction of the charge generating layer-coated cylindrical substrate 1 and the applicator roll 2 is the same, and the peripheral speed of rotation is 10.2 m / min for the charge generating layer-coated cylindrical substrate 1 and 10. 2 m / min.

After the applicator roll 2 is rotated, the paint tank 52 containing the charge generating layer paint 5 is raised by a lifting device (not shown), and the lower part of the applicator roll 2 is immersed. A coating film was formed on the outer periphery of.

Thereafter, coating was started by rotating the cylindrical substrate 1 while approaching the applicator roll 2 until the above-mentioned gap width was reached. This allows applicator roll 2
The above coating material was transferred within 0.5 seconds over the entire width of the cylindrical substrate 1 coated with the charge generation layer 1 in the axial direction. Two seconds after the start of coating, the cylindrical state 1 was separated from the applicator roll 2 by maintaining the rotating state for 3 seconds, narrowed from 400 μm to 90 μm by the gap adjusting device 93 connected to the commadactor 62.

The charge-generating layer-coated cylindrical substrate 1 coated with the charge-transporting layer was air-dried while being rotated for 12 minutes, and then dried at 120 ° C. for 60 minutes by a hot-air circulation dryer.

The film thickness after drying was measured with a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 25.1 μm.

(Comparative Example 1) In applying the charge transport layer coating material used in Example 3 to the charge generating layer coating cylindrical substrate 1 obtained in Example 2, the applicator roll 2 and the metering roll 3 Was carried out under the same conditions and operation as in Example 3 except that the gap width between the first and second steps was set to 300 μm from the beginning until the coating was completed. The reason why the gap width between the applicator roll 2 and the metering roll 3 was set to 300 μm is that the gap width is equal to that of Example 3 around the outer periphery of the charge generating layer-coated cylindrical substrate 1. This is because a film can be formed. While rotating the charge-generating-layer-coated cylindrical substrate 1, it is brought close to the applicator roll 2 until the above-mentioned gap width is reached, and the paint on the applicator roll 2 is partially transferred to the charge-generating-layer-coated cylindrical substrate 1; It took 3 seconds for the transition portion to gradually spread over the entire width of the charge-generating layer-coated cylindrical substrate 1 in the axial direction. After maintaining the rotating state for 5 seconds, the charge generating layer-coated cylindrical substrate 1 was separated from the applicator roll 2.

The charge-generating layer-coated cylindrical substrate 1 coated with the charge transport layer was air-dried while being rotated for 12 minutes, and then dried at 120 ° C. for 60 minutes by a hot-air circulation dryer.

The thickness of the film after drying was measured with a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 25.4 μm. The film thickness distribution in the axial direction is shown in FIG. 10, and the film thickness distribution in the circumferential direction is shown in FIG.

(Comparative Example 2) In Comparative Example 1, while rotating the cylindrical substrate 1 coated with the charge generating layer, the cylindrical substrate 1 was brought close to the applicator roll 2 until the gap width described above was reached. The time from the start of the partial transfer to the layer-coated cylindrical substrate 1 to the end of the coating and the separation of the charge-generating layer-coated cylindrical substrate 1 from the applicator roll 2 is 5. 5 seconds.

The charge-generating layer-coated cylindrical substrate 1 coated with the charge-transporting layer was air-dried while being rotated for 12 minutes, and then dried at 120 ° C. for 60 minutes by a hot-air circulation dryer.

The film thickness after drying was measured with a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 22.4 μm. The thickness distribution in the axial direction is shown in FIG. 10, and the thickness distribution in the circumferential direction is shown in FIG.

From the above Examples and Comparative Examples, it can be seen that according to the method of the present invention, the transfer of the paint to the entire width of the cylindrical substrate is promptly performed. 10 and 11 that the film thickness of the coating film according to the present invention is more uniform than that of the comparative example. This will be described with reference to the drawings. FIG. 12 is a diagram illustrating the application according to Example 3, and FIG. 13 is a diagram illustrating the application according to the comparative example.

As shown in FIG. 12, in the embodiment, the gap between the applicator roll 2 and the metering roll 3 is initially set to four.
The thickness was set to 20 μm (FIG. 12A), and then reduced to 100 μm (FIG. 12B). Accordingly, the thickness of the coating film formed on the outer periphery of the applicator roll 2 is large when the gap is 420 μm, but becomes thin when the gap is 100 μm. In a state where the gap is 100 μm, the amount of the paint 5 in the paint pool formed between the cylindrical substrate 1 and the applicator roll 2 decreases, and therefore, even when the cylindrical substrate 1 is separated, the paint pool is caused by the paint pool. The convexity is small.

On the other hand, when the gap between the applicator roll 2 and the metering roll 3 is always 300 μm as in Comparative Example 1, the thickness of the coating film formed on the outer periphery of the cylindrical substrate 1 is equal to that of Example 3. However, the thickness of the coating film formed on the outer periphery of the applicator roll 2 is increased, and accordingly, the amount of the paint 5 in the paint pool formed between the cylindrical substrate 1 and the applicator roll 2 Increase. Therefore, when the cylindrical substrate 1 is separated in this state, a large protrusion resulting from the paint pool is formed.

Therefore, in order to obtain a coating film having a uniform film thickness, the gap between the applicator roll 2 and the metering roll 3 must be widened at the beginning of coating, but must be narrowed thereafter.

[0109]

According to the present invention, the paint can be quickly transferred from the application roll to the cylindrical substrate, and a uniform coating film can be formed on the outer periphery of the cylindrical substrate with a simple control. . Therefore, an electrophotographic photosensitive drum having a photosensitive layer having a uniform coating film on the outer periphery of the cylindrical substrate can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is a side view showing an embodiment of the present invention.

FIG. 4 is a side view showing an embodiment of the present invention.

FIG. 5 is a side view showing an embodiment of the present invention.

FIG. 6 is a side view showing an embodiment of the present invention.

FIG. 7 is a side view showing an embodiment of the present invention.

FIG. 8 is a schematic diagram showing a case where a cylindrical substrate and an applicator roll are rotated in the same direction.

FIG. 9 is a schematic diagram showing a case where a cylindrical base and an applicator roll are rotated in opposite directions.

FIG. 10 is a graph showing the axial film thickness distribution of the electrophotographic photosensitive drums obtained in Example 3, Comparative Examples 1 and 2.

FIG. 11 is a graph showing the film thickness distribution in the circumferential direction of the electrophotographic photosensitive drum obtained in Example 3, Comparative Example 1, and Comparative Example 2.

FIG. 12 is a view showing a coating process in Example 3.

FIG. 13 is a view showing a coating process of Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical substrate 2 Applicator roll 3 Metering roll 4 Cleaning doctor 5 Paint 6 Gap setting doctor 7 Pickup roll 8 Paint pool 9 Gap adjusting drive

Claims (8)

[Claims] In a method of applying a coating material supplied to an application roll to a cylindrical substrate, the coating film thickness on the outer periphery of the application roll at the beginning of application is finally formed on the cylindrical substrate. A method for applying a coating material to a cylindrical substrate, wherein the coating film thickness is made larger than the coating film thickness to be formed, and thereafter the coating film thickness is reduced. 2. The method for applying a paint to a cylindrical substrate according to claim 1, wherein the coating is performed while rotating the cylindrical substrate and the application roll in the same direction. 3. The method for applying a coating to a cylindrical substrate according to claim 1, wherein the coating is uniformly controlled after the coating thickness is reduced. 4. The method for applying a paint to a cylindrical substrate according to claim 1, wherein the paint film thickness on the outer periphery of the application roll is controlled by a paint measuring means comprising a cylindrical member. 5. The method for applying a paint to a cylindrical substrate according to claim 1, wherein the control of the thickness of the paint on the outer periphery of the applying roll is performed by a paint measuring means comprising a plate-like member. 6. The cylindrical substrate according to claim 1, wherein the coating film thickness on the outer periphery of the application roll is controlled by a coating material measuring means comprising a columnar member having an elliptical section in cross section. How to apply paint to 7. The method according to claim 1, wherein the gap width between the paint metering means and the application roll is G1, and the gap width between the cylindrical substrate and the application roll is G2, G1 ≧ 1.5G2 at the beginning of the application. 7. The method for applying a paint to a cylindrical substrate according to any one of 4 to 6. 8. A method for manufacturing a photosensitive drum for electrophotography in which the photosensitive coating material for electrophotography supplied to a coating roll is applied to a base of the photosensitive drum for electrophotography and then dried. The film thickness is made thicker than the paint film thickness finally formed on the cylindrical substrate, then the paint film thickness is reduced, and thereafter the film thickness is controlled to be uniform, and the film is applied to the electrophotographic photosensitive drum substrate. A method for manufacturing a photosensitive drum for electrophotography, comprising rotating a roll in the same direction.