JPH0321223B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating device, and more particularly to a coating device suitable for coating an electrophotographic photoreceptor on the outer peripheral surface of a cylindrical body.

Methods for coating the outer circumferential surface of a substrate to be coated, such as a cylindrical body, include a spray method, a dipping method, a vertical coating method using a ring-shaped liquid container,
Various methods are known, such as a curtain coating method, a blade coating method, a roll coating method, and an extrusion method.

However, while the spray method is excellent in mass production, it has the disadvantages of a small amount of coating per application and poor surface smoothness, and
This method is not suitable as a coating method for electrophotographic photoreceptors, which require a coating layer with a wide range of film thickness and extremely high surface smoothness.

The dipping method is a relatively simple method, but there is a large difference in film thickness between the upper and lower parts of the cylindrical body, and when coating two or more layers, it is difficult to coat each layer with the same solvent system. The disadvantage is that the lower layer is easily damaged, and furthermore, mass productivity is poor.

Unexamined Japanese Patent Publication No. 1983-22544, No. 1983-101149, No. 1983-
11064, 180261, 1983, etc., the ring coating method has the advantage that the surface smoothness of the coating layer is excellent and the contact time with the coating liquid is short, making it suitable for multilayer coating. In the ring coating method, an elastic ring with an inner diameter slightly smaller than the outer diameter of a cylindrical body is integrated with an outer cylinder of a liquid container, and the cylindrical body is passed through this ring to connect it to the outer surface of the cylindrical body. A coating liquid is supplied to the formed coating chamber and applied to the outer surface of the cylindrical body by moving either or both of the cylindrical body and the ring.
However, in this ring coating method, it is difficult to coat a large number of cylindrical bodies in succession due to the structure of the apparatus. For example, unless the first cylindrical body and the second cylindrical body are completely joined without any gaps and passed through the ring, the coating chamber will not be formed and the coating liquid will leak out and cause the second cylindrical body to pass through the ring. This results in contamination. Furthermore, in the case where the cylindrical body is supplied by the lower elevating means and passed through the application ring and discharged by the upper elevating means, the speed of both elevating means is reduced during the transfer from the lower elevating means to the upper elevating means. Must match exactly.
Moreover, when the first cylindrical body and the second cylindrical body are joined, the speeds of both cylindrical bodies must be completely matched, otherwise an impact will occur during joining, and the coated surface will be disturbed. This is because. In addition, if the joint is not precise enough to be considered as a single cylindrical body, liquid will accumulate at the mismatched part of the joint, and this pool will drip onto the outer surface of the second cylindrical body. This may disturb the coated surface or penetrate into the inner surface of the joint and stain the inner surface of the second cylindrical body.

An object of the present invention is to solve the problems of the ring coating method as described above, and to provide a coating device that can continuously coat the outer peripheral surface of a substrate to be coated, such as a cylindrical body. be.

Other objects and advantages of the present invention will be understood from the following description.

The above-mentioned object of the present invention is to provide a liquid reservoir for a coating liquid between the container outer cylinder and the container inner cylinder, the upper end of which is set lower in height than the container outer cylinder and which has an elastic ring at the upper end. is a device for applying a coating liquid to the outer circumferential surface of a cylindrical body that passes upward through the inner cylinder of a container, and the liquid level is adjusted to the inner cylinder of the container by means of vertically varying the liquid level in the liquid reservoir. This was achieved by using a coating device that is characterized by being positioned higher than the upper end of the coating device.

Hereinafter, the present invention will be explained in more detail using the drawings.

FIG. 1 is a schematic view of the main parts showing the process of continuously coating a cylindrical body using the coating apparatus of the present invention. 2 and 3 are cross-sectional views showing an example of the ring-shaped liquid container 7 in FIG.
The figure shows the state immediately before the start of coating. FIG. 4 is a sectional view showing another example of a ring-shaped liquid container. In FIG. 1, lifting devices 1 and 13 are provided with means for lifting and lowering at a constant speed. The means for raising and lowering may be any known method, such as a motor, a hydraulic cylinder, a pneumatic cylinder, etc.

Rods 2 and 12 are connected to the lifting devices 1 and 13, respectively, and the tips of the rods 2 and 12 are connected to a first cylindrical body 5 and a second cylindrical body 9, respectively.
There is a holder (not shown) that can hold the cylindrical body from the inside. The retainer may be of a known type, for example an expandable three-claw retainer. The detection device 3 and the light source 4 are located at a position where the detection device 3 operates when the cylindrical body 5 blocks the light beam, and these positions are installed at coincident positions immediately before the coating of the cylindrical body 5 is completed. There are no particular restrictions on the detection device, and limit switches, metal detection proximity switches, electrostatic switches, etc. can be used.

The cylindrical body 5 passes through the ring-shaped liquid container 7 and is applied while being raised at a constant speed by the lifting device 1. During coating, a coating liquid is supplied from the coating liquid supply pipe 8 in an amount equal to the amount consumed by coating. When the coating progresses and the cylindrical body 5 eventually blocks the light beam emitted from the light source 4, the detection device 3 is activated. FIG. 2 shows the state of the coating device immediately before the detection device 3 operates. When the detection device 3 operates, the elevating device 6 and the liquid level changing member 73 connected thereto operate and rise. The lifting device 6 and the liquid level changing member 73 are connected to the connecting rod 7
It is connected by 2. At the same time, it is preferable to cut off the supply of the coating liquid from the coating liquid supply pipe 8. The lifting distance of the lifting device 6 is defined as the height at which the liquid level of the coating liquid 74 in the liquid reservoir exceeds the elastic ring 71 at the tip of the container inner cylinder, which is set lower in height than the container outer cylinder 75 (see Fig. 2). ) to a height below the elastic ring 71 due to the rise of the liquid level varying member 73 (the third
(Fig.) is required at least. Preferably the third
As shown in the figure, the liquid level is adjusted so that the movement of the lifting device 6 is stopped while the liquid level changing member 73 does not come out of the liquid level and a portion of its tip remains in the liquid. However, since both ends of the cylindrical body are generally not used as photoreceptors, the member 73 may escape from the liquid surface.

The first cylindrical body 5 continues to rise and passes through the elastic ring 71, completing the application.

Since the coating liquid level is lower than the tip of the elastic ring 71 due to the rise of the liquid level changing member, the coating liquid 74 does not leak out from the liquid container 7.

The cylindrical body 5 that has been coated is discharged to the next process, for example, a drying process (not shown). After the rod 2 has been discharged, the elevating device 1 raises the second cylindrical body 9 and returns it to the position for coating. On the other hand, the lifting device 13 and the rod 1 connected to it
2. Holder at the tip of rod 12 (not shown)
The cylindrical body 9 held in is ready for the next application.

The cylindrical body 9 is raised by the lifting device 13, and stops when its tip reaches the elastic ring 71. The stop position is detected when the cylindrical body 9 no longer blocks the light emitted from the light source 11, so that the detection device 10 operates and the lifting operation of the lifting device 13 is stopped. This state is shown in FIG. At the same time, the holder at the tip of the rod 2, which had finished discharging and descended, holds the cylindrical body 9 (not shown), and the detection device 10 operates, causing the lifting device 6 to lower the liquid level changing member 73. As a result, the coating liquid level becomes higher than the tip of the elastic ring 71, and as a result, the coating liquid 74 comes into contact with the outer peripheral surface of the cylindrical body 9 and becomes ready for coating. At the same time as the lifting device 1 starts to rise at a constant speed, the coating liquid is supplied from the coating liquid supply pipe 8 and coating starts. The lifting device 13 is lowered in preparation for the feeding of the next cylindrical body.

By repeating the above operations, it becomes possible to perform continuous application by supplying cylindrical bodies at intervals.

The coating device of the present invention is characterized by having means for varying the level of the coating liquid above and below the tip of the elastic ring, respectively, at the start and end of coating on one cylindrical body.

One such means is to raise and lower the level of the coating liquid at the tip of the elastic ring by dipping it in the coating liquid 74 and pulling it out of the coating liquid, as described above with reference to FIGS. 2 and 3. This is a method using a volume body (liquid level changing member 73).

Another preferred method is to provide a coating liquid discharge pipe 82 equipped with a valve 81 that opens and closes according to the operation of the detection devices 3 and 10, as shown in FIG. This method has the advantage that it can be applied continuously by simply opening and closing the valve 81 without having to stop the liquid supply from the coating liquid supply pipe 8.Other explanations refer to the explanations in FIGS. 1 to 3. be able to. It is preferable for the coating liquid discharge pipe 82 to extend into the coating liquid to a position slightly lower than the tip of the elastic ring, as shown in FIG. 4, because the liquid level can be quickly maintained until the start of the next coating.

In the coating device of the present invention, the lifting device 1 or 1
If a plurality of units 3 are installed, continuous coating of cylindrical bodies can be performed more efficiently. Furthermore, a plurality of coating liquid supply pipes 8, coating liquid discharge pipes 82, etc. can be provided.

The viscosity of the liquid applied using the coating apparatus of the present invention can be selected from a wide range, but is usually about 0.5 to 1000 centipoise (CP), preferably 1 to 500 CP.

The coating apparatus of the present invention is suitable for manufacturing electrophotographic photoreceptors that require a thin and highly uniform coated surface. It can also be used for other purposes. Examples are shown below.

Example 1 Using the ring-shaped liquid container 7 shown in Figure 4 of the coating device shown in Figure 1, the following dispersion was applied onto the outer peripheral surface of a 116φ aluminum tube (length 33 cm). .

Polystyrene 16g Copper phthalocyanine 3.2g Adjusted to 100ml with xylene It was applied continuously to 30 aluminum tubes by the method described above at a coating speed of 10mm/sec. and dried. The coating film thickness was 20 μm. When the potential was measured after drying, it was 5% in the circumferential direction and length direction.
It was confirmed that the same quality could be ensured with good reproducibility for a large number of cylindrical bodies, with only fluctuations in potential within a range of less than 30 degrees.

Example 2 In the coating solution of Example 1, the total amount was xylene.
Example 1 was repeated except that the volume was adjusted to 1000 ml. This coating layer had a thickness of about 0.3 μm and was a uniform thin film layer that could be used as a charge generation layer.

[Brief explanation of the drawing]

FIG. 1 is a schematic view of the main parts of the process of coating a cylindrical body using the coating apparatus of the present invention. 2 and 3 are cross-sectional views showing one example of the coating apparatus of the present invention, and FIG. 4 is a cross-sectional view showing another example. 1, 6, 13... Lifting device, 5, 9... Cylindrical body, 3, 10... Detecting device, 4, 11... Light source, 71... Elastic ring, 73... Liquid level changing member, 75... ...Liquid container outer cylinder, 8...Coating liquid supply pipe, 81...Valve, 82...Coating liquid discharge pipe, 7
6... Coating layer, 2, 12, 72... Rod.

Claims (1)

[Claims] 1. A liquid reservoir for the coating liquid is provided between the container outer cylinder and the container inner cylinder, the height of which is set lower than the upper end of the container outer cylinder, and which has an elastic ring at the upper end. A device for applying a coating liquid to the outer circumferential surface of a cylindrical body passing upward through the container, the liquid level being made higher than the upper end of the inner cylinder of the container by means of vertically varying the liquid level in the liquid reservoir. A coating device characterized in that it is adapted to apply .