JPH08222B2 - Drum application method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of applying a coating liquid such as a photosensitive material onto the outer peripheral surface of a cylindrical drum, such as an electrophotographic photosensitive drum.

(Prior Art) For example, when an electrophotographic photosensitive drum is manufactured by applying a coating liquid containing a photosensitive substance onto the outer peripheral surface of a cylindrical drum, the outer peripheral surface of the drum has a uniform film thickness. It is important to apply to. As a method for manufacturing an electrophotographic photosensitive drum, there is a dipping method in which a cylindrical drum is immersed in a coating solution and the drum is withdrawn axially from the coating solution. In such a dipping method, in order to prevent the coating liquid from being applied to the inner peripheral surface of the drum and to prevent the coating liquid surface from moving up and down when the drum withdraws from the coating liquid, an outer diameter equal to the outer diameter of the drum is used. The drum is raised and lowered using a cylindrical seat having a diameter. The pedestal is arranged so that it can be moved up and down in the coating liquid so that the axis of the pedestal is substantially vertical, and the pedestal is moved up and down with the drum placed on the pedestal. To apply the coating liquid to the outer peripheral surface of the drum, place the drum whose upper end surface is in an airtight state on the pedestal, and lower the pedestal so that the drum is immersed in the coating liquid, It is done by raising. At this time, the upper end of the pedestal is retracted from the coating liquid so that the entire drum is retracted from the coating liquid, and the upper surface of the pedestal is positioned above the coating liquid surface.

An organic solvent such as tetrahydrofuran is used for the coating liquid used for manufacturing the photosensitive drum. Since the organic solvent deteriorates the elastic body such as natural rubber or synthetic rubber, the elastic body made of rubber cannot be used for the pedestal immersed in the coating solution. Therefore, fluororesin is
A hard material such as metal is used, and the lower end surface of the drum mounted on the upper surface of the pedestal does not become liquid-tight with the upper surface of the pedestal, and the inside of the lower end portion of the drum is immersed when the drum is immersed in the coating liquid. The coating liquid penetrates into. The coating liquid that has penetrated into the drum is located on the upper surface of the pedestal, and the coating liquid on the pedestal may be dried while the upper surface of the pedestal is withdrawn from the coating liquid and the drum on the pedestal is replaced. If there is dry matter on the pedestal,
The drum may not be able to be placed on the pedestal. When the pedestal is immersed in the coating liquid, the dried material attached to the pedestal may be released into the coating liquid and adhere to the outer peripheral surface of the drum. Thus, if the dried material of the coating liquid adheres to the outer peripheral surface of the drum, it cannot be used as an electrophotographic photosensitive drum.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and an object thereof is to prevent the coating liquid from drying on the upper surface of the pedestal, and therefore to prevent the coating liquid from being applied to the coating liquid. An object of the present invention is to provide a drum coating method in which a dried product is not likely to be mixed.

(Means for Solving Problems) A drum coating method according to the present invention comprises a step of placing a drum on a pedestal whose axis is substantially vertical, and a step of lowering the pedestal on which the drum is placed to apply the drum. A step of immersing in the liquid, a step of raising the pedestal to apply the coating liquid to the outer peripheral surface of the drum so as to move the drum immersed in the coating liquid out of the coating liquid,
The method is characterized in that the pedestal on which the drum is placed is always moved up and down so that the upper surface of the pedestal is placed below the surface of the coating liquid, thereby achieving the above object. It

(Examples) Examples of the present invention will be described below.

In the method of the present invention, as shown in FIG. 1, a cylindrical pedestal 20 having an outer diameter equal to the outer diameter of the drum 10 to be coated with the coating liquid on the outer peripheral surface is used. The pedestal 20 is arranged so as to be able to move up and down within the coating liquid. For example, when an organic solvent such as tetrahydrofuran is used as the coating liquid for manufacturing an electrophotographic photosensitive drum, a fluorine resin, a metal, etc. Composed of.

An upper end portion of the pedestal 20 is a fitting portion 21 having a diameter reduced by the thickness of the drum 10 so that the lower end portion of the drum 10 can be fitted onto the outer periphery. The pedestal 20 is elevated and lowered so that the upper surface thereof is always located below the coating liquid surface, and the uppermost position of the upper surface of the pedestal 20 is slightly below the coating liquid surface. At this uppermost position, the drum 10 is placed on the upper surface of the pedestal 20, and the drum 10 having the outer peripheral surface coated with the coating liquid is removed from the pedestal 20.

The drum 10 placed on the pedestal 20 is a chucking device 30.
Is held by The chucking device 30 is hermetically fitted to the inner peripheral surface of the drum.

In the drum coating method of the present invention carried out by such a coating apparatus, first, the pedestal 20 is set to the uppermost position with its upper surface slightly lower than the coating liquid level, and held by the chucking apparatus 30 in such a state. The drum 10 thus mounted is placed on the pedestal 20. As shown in FIG. 2, the drum 10 has its lower end fitted to the fitting portion 21 of the pedestal 20 and is coaxial with the pedestal 20. At this time, when the drum 10 is placed on the pedestal 20, the coating liquid located above the pedestal 20 is
Located in the lower end of 10. Therefore, the upper surface of the pedestal 20 is immersed in the coating liquid.

The pedestal 20 is lowered with the drum 10 placed thereon, and the drum 10 is immersed in the coating liquid as shown in FIG.
After that, the pedestal 20 is raised at a constant speed, and the drum 10 exits from the coating liquid at that speed. Then, during this withdrawal, the coating liquid is applied to the outer peripheral surface of the drum 10 to have a predetermined film thickness.

As the pedestal 20 rises, the pedestal 20 is stopped with its upper surface at the uppermost position slightly below the coating liquid surface. As a result, the drum 10 placed on the pedestal 20 is brought into a state similar to the state shown in FIG. 2 in which the lower end portion is immersed in the coating liquid surface. Then, in such a state, the chucking device 30
Moves upwards, the drum 10 is removed from the pedestal 20,
The state is similar to that shown in FIG.

In this way, since the pedestal 20 moves up and down within the surface of the coating liquid, the upper surface of the pedestal 20 does not move upward from the coating liquid, and there is no possibility that the upper surface is constantly immersed in the coating liquid and dried.

Since the lower end of the drum 10 is withdrawn from the coating liquid by the chucking device 30, it is withdrawn from the coating liquid at a speed different from the lifting speed of the pedestal 20. Therefore, the coating liquid is applied to the outer peripheral surface of the lower end portion in a film thickness different from the film thickness of the coating liquid applied by raising and lowering the pedestal 20. However, in the electrophotographic photosensitive drum, since an image is not formed at each end, even if the thickness of the coating liquid changes at each end and the thickness of the photosensitive layer changes, no problem occurs. Absent. Therefore, the pedestal 20 is made to correspond to the non-image forming area where the film thickness of the coating liquid may change.
The uppermost position of is determined. That is, the pedestal 20 is so set that the lower end area of the drum placed on the pedestal 20 which is always located below the coating liquid surface is smaller than the non-image forming area.
The uppermost position of is set.

When the drum 10 is placed on the pedestal 20, since the upper surface of the pedestal 20 is located below the surface of the coating liquid, the coating liquid remains in the lower end portion of the drum 10 and the coating liquid is applied to the inner peripheral surface of the lower end portion of the drum 10. Will adhere to. As a result, it is necessary to wipe the inner peripheral surface of the lower end portion of the drum 10 after applying the coating liquid on the outer peripheral surface of the drum 10. Such a wiping operation is similar to the wiping operation performed in the conventional dip coating method. For example, place the upper surface of the pedestal 20 above the surface of the coating liquid and place the drum on the pedestal 20.
10 is placed and the pedestal 20 is moved up and down to apply the coating liquid to the outer peripheral surface of the drum 10, and then the upper surface of the pedestal 20 is positioned above the coating liquid surface and the drum 10 is removed from the pedestal 20. Even in the dipping method, the upper surface of the pedestal 20 and the drum 10
Since the lower end surface is not completely liquid-tight, a small amount of the coating liquid penetrates into the drum 10, and the coating liquid also adheres to the inner peripheral surface of the lower end portion of the drum 10. Therefore, even in the conventional dip coating method, it is necessary to wipe the coating liquid adhering to the inner peripheral surface of the lower end portion, and in the case of the method of the present invention, the same wiping operation as the conventional wiping operation may be performed. .

In the chucking device used in the drum coating device of the above-described embodiment, the volume of the coating liquid evaporating and drying increases when the volume of the drum surrounded by the pedestal and the chucking device is large. Therefore, a chucking device having a large volume may be used. In this case, the amount of gas entering the drum is reduced, and the amount of evaporated and dried coating liquid can be reduced.

(Effects of the Invention) According to the method of the present invention, since the upper surface of the pedestal is always immersed in the coating liquid in this manner, there is no fear that the coating liquid will be dried on the upper surface of the pedestal. Will not be mixed in the coating liquid and will not adhere to the outer peripheral surface of the drum.

[Brief description of drawings]

FIG. 1, FIG. 2 and FIG. 3 are explanatory views in one embodiment of the method of the present invention. 10 …… drum, 20 …… pedestal, 21 …… fitting part, 30 …… chucking device.

Claims (1)

[Claims] 1. A step of placing a drum on a pedestal having a substantially vertical axis, a step of lowering the pedestal on which the drum is placed to immerse the drum in the coating liquid, and immersing the drum in the coating liquid. This is a drum coating method that includes a step of raising the pedestal to apply the coating liquid to the outer peripheral surface of the drum so as to move the drum out of the coating liquid. The upper surface of the pedestal on which the drum is placed is always the coating liquid level. A drum coating method, wherein the pedestal is moved up and down so as to be located below.