JPH0497257A - Method for coating drum - Google Patents

Abstract

PURPOSE:To remove the unevenness of an application solution applied to the outer periphery of a drum by dipping the drum into the application solution in a tank while agitating the solution and receding the drum from the solution in the suspending state of its agitation. CONSTITUTION:In the case of dipping the drum 10 into the application solution 20, the application solution 20 is agitated and a high concentration application solution part stayed in the solution 20 is agitated and resolved in the solution 20. Since the solution 20 into which the drum 10 is dipped is allowed to flow upwards and overflowed, the high concentration application solution part resolved in the solution 20 in the dipped state of the drum 10 into the solution 20 is overflowed to the outside of the tank 30. Then, the drum 10 is receded from the solution 20. Thus, the generation of unevenness of the solution applied to the outer periphery of the drum 10 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method for applying a coating liquid containing a photosensitive substance to a drum, for example, when manufacturing an electrophotographic photosensitive drum in which a photosensitive layer is formed on the outer peripheral surface of the drum. The present invention relates to a drum coating method for coating an outer peripheral surface.

(Prior Art) There are various methods for manufacturing electrophotographic photoreceptor drums by applying a coating liquid containing a photosensitive substance to a drum. One of the coating methods is a dipping method in which a drum is vertically immersed in a coating solution and the drum is withdrawn from the coating solution in the axial direction of the drum.

In this immersion method, the withdrawal speed of the drum from the coating liquid and the uniformity of the composition of the coating liquid have a large influence on the uniformity of the thickness of the coating liquid applied to the outer peripheral surface of the drum. For this purpose, by causing the coating liquid to continuously flow into the tank from the lower end of the tank containing the coating liquid, the coating liquid is constantly overflowing from the upper end surface of the tank, and the coating liquid is flown into the tank at a predetermined speed pattern. The drum is removed from the coating solution.

(Problem to be Solved by the Invention) When applying a coating liquid to the outer peripheral surface of the drum using such a dipping method, when the drum is removed from the coating liquid, the excessive coating liquid applied to the outer peripheral surface of the drum is removed. flows down along the outer circumferential surface of the drum. This flow of coating liquid continues even after the drum is completely evacuated from the coating liquid. Therefore, when the drum is withdrawn from the coating liquid and moves away from the surface of the coating liquid, as shown in FIG. Fall to the liquid surface.

The excess coating liquid 21 that falls from the lower end surface of the drum 10 onto the liquid surface of the coating liquid 20 in the tank 30 is because the solvent has evaporated from the coating liquid in the tank 30 because a suitable amount of time has passed. , the concentration is higher than that of the coating liquid 20 in the tank 30. Moreover, since the excess coating liquid 21 flows down along the outer peripheral surface of the drum 10 and the drum 10 and the tank 30 are relatively separated from each other, this excess coating liquid 21 flows down the tank 30.
It falls with relatively high acceleration into the coating liquid 20 inside. As a result, the coating liquid 21 settles to a relatively deep place below the surface of the coating liquid 20 in the tank 30.Furthermore, the tank 30 has an inner diameter slightly larger than that of the drum 10. Therefore, the excess coating liquid 21 that falls along the outer circumferential surface of the drum 10 falls to a position close to the inner circumferential surface of the tank 30. The rising speed of the coating liquid 20 in the tank 30 becomes slower as it moves away from the axis of the tank 30, so the rising speed of the coating liquid 20 in the tank 30 is slowest near the inner peripheral surface of the tank 30 where the excess coating liquid 21 falls. ing.

Therefore, even though the coating liquid 20 in the tank 30 is constantly overflowing, the excess coating liquid 21 that has fallen into the tank 30 from the lower end surface of the drum 10 is
The liquid is not discharged outside, but remains along the inner circumferential surface of the upper end of the tank 30, forming a highly concentrated coating liquid portion 22. In this way, when the highly concentrated coating liquid portion 22 is formed in the coating liquid in the tank 30, when the drum 10 is next immersed in this tank 30 and the coating liquid is applied to the outer peripheral surface of the drum 1o. ,
A highly concentrated coating liquid portion adheres to the outer peripheral surface of the drum 10,
So-called uneven coating occurs.

The present invention solves the problems of the prior art as described above, and an object of the present invention is to provide a drum coating method that does not cause uneven coating of the coating liquid applied to the outer peripheral surface of the drum.

(Means for Solving the Problems) The drum coating method of the present invention involves immersing the drum vertically in the coating liquid in the tank with the coating liquid stored in the tank overflowing from the tank. A drum coating method in which a coating liquid is applied to the outer peripheral surface of a drum by withdrawing the drum from the coating liquid in the axial direction, and the drum is immersed in the coating liquid in a tank while stirring the coating liquid. , and a step of removing the drum from the coating liquid in the tank while preventing stirring of the coating liquid, thereby achieving the above object.

Further, the drum coating method of the present invention includes the steps of: immersing the drum vertically in the coating liquid in the tank with the coating liquid stored in the tank overflowing the tank; and then rotating the drum from the coating liquid. A drum coating method in which the coating liquid is applied to the outer circumferential surface of the drum by withdrawing it in the center direction, and the coating liquid flowing down the outer circumferential surface of the drum is applied to the drum after leaving the coating liquid in the tank. It is characterized by being stopped at a predetermined position for a predetermined period of time where it does not settle by more than a predetermined amount, thereby achieving the above object.

(Function) In the drum coating method of the present invention, since the coating liquid is stirred when the drum is immersed in the coating liquid, the high concentration coating liquid portion remaining in the coating liquid is stirred, and the coating liquid remains in the coating liquid. dissolve. The coating liquid in which the drum is immersed flows from the bottom to the top and overflows, so when the drum is immersed in the coating liquid, the high concentration coating liquid dissolved in the coating liquid flows into the tank. overflows to the outside. The drum is then removed from the coating liquid.

In another drum coating method of the present invention, the drum that has been removed from the coating liquid is stopped at a predetermined position above the surface of the coating liquid for a predetermined period of time. At this time, the coating liquid flowing down along the outer peripheral surface of the drum does not fall beyond a predetermined amount into the overflowing coating liquid in the tank, and is discharged to the outside of the tank together with the overflowing coating liquid.

(Example) The present invention will be described below with reference to Examples.

The drum coating method of the present invention is carried out when manufacturing an electrophotographic photosensitive drum by coating the outer peripheral surface of the drum with a coating liquid containing a photosensitive substance.

The drum coating method is carried out using the apparatus shown in FIG. In this drum coating device, the drum 10 is held vertically by a drum chucking device (not shown) disposed above a cylindrical tank 30 containing the coating liquid 2o. When the drum 10 is held vertically above the tank 30 by the drum chucking device, the drum 1
The tank 30 is raised and lowered, and the coating liquid 20 and the drum 10 are raised and lowered relative to each other so that the drum 10 is immersed in the coating liquid 20 in the tank 30.

When the drum 10 is immersed in the coating liquid 20 in the tank 30 to a predetermined depth, the tank 30 is lowered so that the drum 10 is withdrawn from the coating liquid 20 in the axial direction.

The tank 30 containing the coating liquid 20 is opened from the bottom of the tank 30.
By continuously flowing the coating liquid 20 into the tank 30, the coating liquid 20 always overflows from the upper end surface of the tank 30. An annular liquid receiver 31 is provided on the outer peripheral surface of the upper end of the tank 30, into which the coating liquid 20 overflowing from the upper end of the tank 30 flows. The liquid receiver 31
The coating liquid 20 that has flowed into the tank 30 is re-flowed into the tank 30 from the bottom of the tank 30 via a circulation path (not shown).

The tank 30 is provided with a float-type stirring means 50 that moves up and down within the tank 30 in the axial direction.

The stirring means 50 has a float 51 in the shape of an inverted truncated cone. As shown in FIG. 2, the float 51 is provided with a plurality of communication holes 51b around its axis, through which the coating liquid 20 in the tank 30 flows. The outer peripheral surface of the float 51 excluding the upper end is a tapered surface 51c whose diameter gradually decreases toward the upper end. The outer peripheral surface of the upper end of the float 51 is a straight surface S having a constant outer diameter in the axial direction.
ld, and its outer diameter is sufficiently smaller than the inner diameter of the tank 30.

A plurality of support rods 52 are radially provided on the straight surface 51d of the float 51 at equal intervals in the circumferential direction. Each of the support rods 52 has the same length, and the diameter of the circle formed by connecting the ends of each support rod is slightly larger than the inner diameter of the tank 30. A stirring blade 53 made of fluororesin or the like is attached to the lower surface of each support rod 52. Each stirring blade 5
3 are vertically supported on the outside of the float 51, and are inclined in the same direction and at the same angle with respect to the radial direction of the tank 30. The diameter of the circle formed by connecting the outer edges of each stirring blade 53 is such that each outer edge is connected to the tank 3.
The inner diameter of the tank 30 is slightly smaller than the inner diameter of the tank 30 so as to be close to the inner peripheral surface of the tank 30 .

A guide groove 33 is provided on the inner circumferential surface of the tank 30, into which the tip of each support rod 52 of the stirring means 50 is fitted. The guide groove 33 is connected to the tank 30 as shown in FIG.
A plurality of vertical grooves 33a reach from the upper end to the lower end, and are inclined at a predetermined angle with respect to the vertical line so as to connect the upper end of each vertical groove 33a to the lower end of the adjacent vertical groove 33a. The inclined grooves 33b have a zigzag shape repeated at a predetermined pitch in the circumferential direction. When the drum 10 is not immersed in the coating liquid 20 in the tank 30,
The float 51 of the stirring means 50 moves the coating liquid 2 in the tank 30.
0, the tip of each support rod 52 comes into contact with the outer curved surface 33c of the guide groove 33 at the corner where the upper end of the vertical groove 33a and the upper end of the inclined groove 33b are connected. The curved surface 33c of the connecting corner portion is connected to the stirring means 5.
0, the tip of each support rod 52 is inserted into the inclined groove 3.
It is curved to ensure entry into 3b.

When the drum 10 is immersed in the coating liquid 20 in the tank 30, the stirring means 50 is pressed against the lower end surface of the drum 10, and the tip of each support rod 52 of the stirring means 50 is connected to the inclined groove 33.
Descend within b. As a result, the stirring means 50 sinks into the coating liquid 20 in the tank 30 while rotating in the circumferential direction. When the drum 10 is immersed in the coating liquid 20 in the tank 30 to a predetermined depth, the tip of each support rod 52 reaches the connecting corner of the guide groove 33 between the lower end of the inclined groove 33b and the lower end of the vertical groove 33a. When the drum 10 is removed from the coating liquid 20 in the tank 30, the tip of each support rod 52 moves up within the vertical groove 33a. As a result, the stirring means 50 can rotate the coating liquid 2 in the tank 30 without rotating in the circumferential direction.
Float within 0. The outer curved surface 33d of the guide groove 33 at the connecting corner between the lower end of the inclined groove 33b and the lower end of the vertical groove 33a ensures that the tip of each support rod 52 is connected to the vertical groove 33a when the stirring means 50 starts floating. Let it enter.

In the drum coating device, the coating liquid 20 in the tank 30 contains:
The drum IO is immersed in the coating liquid 20 and withdrawn from the coating liquid 20 one after another. When the preceding drum 10 is withdrawn from the coating liquid 20, the excess coating liquid flows down along the outer peripheral surface of the drum 1. After the lower end surface of the drum 10 is separated from the surface of the coating liquid 20, the excess coating liquid flowing down along the outer peripheral surface of the drum 10 falls from the lower end surface of the drum 10 onto the surface of the coating liquid 20 in the tank 30.

After the preceding drum 10 is completely removed from the coating liquid 20, the agitating means 50 in the tank 30 has its respective support rods 52 at the tips of the guide grooves 33 on the inner circumferential surface of the tank 30.
is in contact with a curved surface 33c at a connecting corner between the upper end of the vertical groove 33a and the upper end of the inclined groove 33b.

In this state, when the tank 30 is raised relative to the drum 10 so that the succeeding drum 10 is immersed in the coating liquid 20 in the tank 30, the drum 10 is immersed in the coating liquid 20. Accordingly, the stirring means 5
0 is pushed downward. As a result, the tips of each support rod 52 of the stirring means 50 descend within the inclined groove 33b, and the stirring means 50 settles within the coating liquid 20 while rotating in the circumferential direction. As the stirring means 50 sediments in the coating liquid 20 while rotating, the coating liquid 20 in the tank 30 is agitated in the circumferential direction mainly in the outer peripheral side of the drum 10 by each stirring blade 33 . As a result, the excess coating liquid that falls from the lower end surface of the preceding drum 10 onto the surface of the coating liquid 20 in the tank 30 forms a highly concentrated coating liquid portion (see FIG. 5) as in the conventional case. The coating liquid 20 in the tank 30
The coating liquid 20 is dispersed inside the tank 30 and further collected in the center where the flow rate is high, and is discharged to the outside of the tank 30 together with the coating liquid 20 that overflows from the upper end surface of the tank 30 .

In the step in which the drum IO is immersed in the coating liquid 20, the uniformity of the composition of the coating liquid 20 does not significantly affect the thickness of the coating liquid applied to the outer peripheral surface of the drum 10.

Therefore, during the dipping step, the coating liquid 20 is stirred,
The excess coating liquid is transferred into the coating liquid 20 into the high concentration coating liquid section 2.
It is effective to adjust the uniformity of the composition of the coating liquid 20 by dispersing the liquid and overflowing from the upper end surface of the tank 30, without forming 2 (see FIG. 5).

When the drum 10 is immersed in the coating liquid 20 in the tank 30 to a predetermined depth, the tips of each support rod 52 of the stirring means 50 move to the connecting corner between the lower end of the inclined groove 33b and the lower end of the vertical groove 33a of the guide groove 33. reach the department. After this state is maintained for a predetermined time, the drum 10 is withdrawn from the coating liquid 20 in the axial direction.

When the drum IO is withdrawn from the coating liquid 20, the stirring means 50 floats in the coating liquid 20 due to the buoyant force acting on the float 51 as the drum IO is withdrawn from the coating liquid 20. From coating liquid 20 to drum 1
In the step in which zero is withdrawn, the uniformity of the composition of the coating liquid 20 has a large effect on the thickness of the coating liquid applied to the outer peripheral surface of the drum 10. However, the excess high concentration coating liquid dispersed in the coating liquid 20 has already been discharged outside the tank 30.
Moreover, since the tips of each support rod 52 of the stirring means 50 rise within the vertical groove 33a, the stirring means 50 floats vertically within the coating liquid 20 without rotating, so that the stirring blade maintains the vertical state. There is no possibility that the coating liquid 20 will be stirred by the liquid 53. As a result, uneven coating does not occur in the coating liquid applied to the outer circumferential surface of the drum 10 from which the coating liquid 20 has been withdrawn.

An example of another drum coating method of the present invention is shown in FIG.

In this embodiment, a normal tank 30 without stirring means is used. Coating liquid 20 contained in tank 30
is always overflowing from the upper end surface of the tank 30 as the coating liquid continuously flows through the tank 30 from the lower part of the tank 30.

In this drum coating method, first, the drum 10 is held vertically above the tank 30 by a drum chucking device. Next, the drum 10 is immersed in the coating liquid 20 in the tank 30, and then the drum 10 is withdrawn from the coating liquid 20 in the axial direction. When the drum 10 is withdrawn from the coating liquid 20, the excess coating liquid applied to the withdrawn portion flows down along the outer peripheral surface of the drum 10.

When the lower end surface of the drum 10 separates from the liquid surface of the coating liquid 20, the excess coating liquid flowing down along the outer peripheral surface of the drum 10 starts to fall from the lower end surface of the drum IO to the liquid surface of the coating liquid 20.

The distance H from the liquid level of the coating liquid 20 to the lower end surface of the drum lO is, for example, 1 to 3IIIl! 1, the lowering of the tank 30 relative to the drum 10 is stopped, and this state is stopped for a predetermined period of time. During this stop, excess coating liquid continues to fall from the lower end surface of the drum 10 onto the surface of the coating liquid 20. The position in the coating liquid in the tank 30 where the excess coating liquid falls is near the inner peripheral surface of the tank 30 where the rising speed of the coating liquid 20 flowing through the tank 30 is the slowest. However, the lower end surface of the drum 10 is coated with the coating liquid 2.
Since it is stopped at a low place, for example, 1 to 3 mm from the liquid level of 0, a large acceleration is not applied to the excess coating liquid that falls from the lower end surface of the drum 10 to the liquid surface of the coating liquid 20.
The excess coating liquid collides with the surface of the coating liquid 20 at a low speed.

As a result, the dropped high-concentration surplus coating liquid does not sink deeply below the liquid surface, but remains near the liquid surface of the tank 30. As a result, the coating liquid is transferred to the tank 30 along with the coating liquid 20 in the tank 30 that overflows from the upper end surface of the tank 30.
Expelled outside.

When a predetermined period of time has elapsed for the excess coating liquid to stop falling from the lower end surface of the drum 10, the tank 30 is further lowered to move the lower end surface of the drum 10 further away from the surface of the coating liquid 20 in the tank 30.

In this way, in the drum coating method of this embodiment, the tank 3
Since there is no risk of high concentration coating liquid remaining near the inner circumferential surface of the upper end surface of the drum, uneven coating of the coating liquid does not occur on the outer circumferential surface of the drum where the coating liquid is then applied to the outer circumferential surface.

When the drum 10 that has been withdrawn from the coating liquid 20 in the tank 30 is temporarily stopped above the liquid level, the distance H from the liquid level to the lower end surface of the drum IO is preferably 1 to 3 m.
It is not limited to this. However, if this distance H is too small, there is a risk that the coating liquid 20 in the tank 30 will bounce back and adhere to the outer peripheral surface of the drum due to falling excess coating liquid. On the other hand, if it is too large, the excess coating liquid that has fallen from the lower end surface of the drum 10 to the surface of the coating liquid 20 will settle below the surface of the coating liquid 20.
There is a possibility that the water will not be discharged outside the tank 30.

(Effects of the Invention) As described above, in the drum coating method of the present invention, when the drum is immersed in the coating liquid stored in the tank, the coating liquid is stirred, so that the high concentration remaining in the coating liquid is reduced. The excess high concentration coating liquid is dispersed in the coating liquid in the tank without forming a coating liquid part, and is collected in the center of the tank where the flow rate is high.
It is ensured that it is discharged outside the tank. Therefore, when the drum is removed from the coating liquid, there is no possibility that uneven coating of the coating liquid will occur on the outer peripheral surface of the drum.

Further, in the drum coating method of the present invention, the excess coating liquid that falls from the lower end of the drum after leaving the coating liquid in the tank does not settle in the coating liquid in the tank by more than a predetermined amount.
Along with the coating liquid overflowing from the tank, a high concentration coating liquid portion is discharged to the outside of the tank. As a result, there is no possibility that uneven coating of the coating liquid will occur on the outer peripheral surface of the drum which is then immersed in the coating liquid and then withdrawn from the coating liquid.

Figure 1 is a longitudinal sectional view of the apparatus used to carry out the drum coating method of the present invention, Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is the tank thereof. FIG. 4 is a schematic diagram for explaining another drum coating method of the present invention, and FIG. 5 is an explanatory diagram of a conventional drum coating method.

DESCRIPTION OF SYMBOLS 10... Drum, 20... Coating liquid, 30... Tank, 33... Guide groove, 33a... Vertical groove, 33b.
... Inclined groove, 50 ... Stirring means, 51 ... Float, 52 ... Support rod, 53 ... Stirring blade.

that's all

Claims (1)

[Claims] 1. With the coating liquid stored in the tank overflowing from the tank, the drum is vertically immersed in the coating liquid in the tank, and the drum is axially oriented from the coating liquid. A drum coating method in which a coating liquid is applied to the outer peripheral surface of a drum by withdrawing the drum, and the drum is immersed in a coating liquid in a tank while stirring the coating liquid, and the drum is removed from the coating liquid in a tank. A drum coating method comprising: , a step of leaving the coating liquid in a state where stirring is prevented. 2. With the coating liquid stored in the tank overflowing from the tank, by immersing the drum vertically in the coating liquid in the tank and withdrawing the drum from the coating liquid in the axial direction, A drum coating method in which a coating liquid is applied to the outer circumferential surface of a drum, in which the coating liquid flowing down the outer circumferential surface of the drum does not settle more than a predetermined amount into the coating liquid in the tank after leaving the drum from the coating liquid in the tank. A drum coating method characterized by stopping at a predetermined position for a predetermined period of time.