JPS61216769A - Method for applying coating agent to cylindrical support - Google Patents

Abstract

PURPOSE:To form an improved coating film having no foreign matter mixed therein with a uniform thickness, by immersing a cylindrical support to be coated in the coating solution in a coating tank forcibly recirculated through a filter and relatively moving the coating tank and the cylindrical support. CONSTITUTION:A definite amount of a coating solution 9 is stored in a coating tank 1 and drawn out from the bottom part of the tank 1 through a pipe 4 by a pump P1 and filtered through a filter 5 to be again returned to the coating solution of the tank 1 to be forcibly recirculated. A cylindrical support 8 to be coated is immersed in the coating solution prevented from the mixing of foreign matter by filtering said coating solution by the filter 5 so that the axial direction thereof is at right angles to the liquid level of the tank 1 and drawn out in the reverse direction at a constant speed to form a homogenous coating film prevented from the adhesion of foreign matter or dust.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a method for coating various cylindrical objects, such as a method for manufacturing an electrophotographic photoreceptor by coating a support with a coating liquid such as a photosensitive liquid.

[Prior art 1] Conventionally, a method of manufacturing an electrophotographic photoreceptor by dipping a cylindrical support in a coating solution and coating it is known as a dip coating method (Japanese Patent Laid-Open No. 57-5047, Utility Model Application No. 1982-
Publication No. 7039). [Problems to be Solved by the Invention] Conventionally, in the dip coating method in which a predetermined amount of coating solution is filled in a cylinder, the support is immersed, and then coated, a film is formed due to evaporation of the solvent in the coating solution. However, there was a problem in that the film adhered to the surface of the support, causing defects in the coating layer, resulting in a high number of defective recording media. This technique uses overflow at the final stage of the rise in the level of the coating solution caused by immersion, and is intended to remove the film formed by this overflow, but it is not effective against the film and dirt floating on the surface of the solution. However, it has little effect on what is present in the liquid. The technique described in Japanese Utility Model Publication No. 57-7039 attempts to prevent the coating liquid from adhering to the inner wall of the sill by using polytetrafluoroethylene on the inner wall. It has been found that depending on the conditions, the coating solution may remain and form a film, which is not a fundamental solution. There shall be no film formed on the surface of the coating liquid in the cylindrical coating tank due to evaporation of the solvent on the surface of the coating liquid, and there shall be no film formed by the adhering liquid remaining on the inner surface of the coating tank, including such films. Good coating with a uniform film thickness and no foreign matter is ensured by ensuring that no foreign matter or dust is mixed into the coating solution in the coating tank, and by using a coating solution that is coated at a uniform coating speed and has a uniform concentration and viscosity. Necessary for forming the surface on the support. In the prior art, there has been no coating method that satisfies these conditions. The present invention aims to solve these problems.

[Means to solve the problem]

The above problems can be solved by the following technical means. That is, the coating tank is filled with a predetermined amount of coating liquid, and the coating liquid is extracted from the bottom of the coating tank using a pump, and the coating liquid that has been filtered through a filter is returned to the liquid in the coating tank and forcedly circulated. A method for applying a coating agent to a cylindrical support, in which the cylindrical support to be coated is immersed in a coating liquid in a tank, and the coating is performed by relatively moving the coating tank and the cylindrical support.

[Example and action]

FIG. 1 is one of the embodiments of the present invention and shows the simplest system. A certain amount of coating liquid 9 is placed in the coating tank 1, and the coating liquid passes through the vibrator 4 from the bottom of the tank to the pump P.
1, filtered through filter 5, and returned to the coating liquid in the tank for forced circulation. Here, the bottom of the coating tank refers not only to the bottom but also to the vicinity of the bottom of the sides of the coating tank where all the coating solution can be drawn out.
As a result, even if foreign matter gets into the tank, it will be removed by the filter 5. In this state, the cylindrical support to be coated is immersed with its axial direction perpendicular to the liquid level of the tank, and vice versa at a constant speed. If you pull it out in the same direction, you will get a homogeneous coating without any foreign matter or dirt. FIG. 2 is a block diagram of a second embodiment of the present invention, and FIG. 11$2-a is a partial top view thereof. This is because the return position of the coating liquid in the first embodiment was below the surface of the coating liquid in the coating tank, whereas in this example, the return position was set at the outer peripheral part 7 near the liquid surface. By returning the liquid uniformly from the outer circumferential direction, the liquid can be efficiently replaced, a liquid stirring effect can be obtained, and there is no room for a film to form on the liquid surface. If the cylindrical support to be coated is immersed in this state and then pulled out to complete the coating, uniform and good coating without contamination of foreign matter will continue. Figure 3 shows that as the coating is continued many times, it must be removed. This is done by precisely sending out the replenishment amount from the replenisher tank 2 with the pump P2, and inserting it in front of the filter 5 shown in the figure to join the circulation system, taking care to prevent foreign matter and dirt from reaching the coating tank. In the fourth embodiment, the replenisher is not supplied from the replenisher tank 2 as shown in FIG. 4 and FIG. It is arranged so that the mouth goes. A replenishment coating liquid 12 is filled in the automatic replenishment bottle 15, which is turned upside down and a replenishment port 13 is attached near the steady liquid level 11 of the coating tank as shown in the figure. As the coating progresses and the level of the liquid level 11 in the coating tank decreases, air enters the air reservoir 14 in the replenishment bottle from the replenishment port 13 and pushes down the liquid level 12 in the bottle, supplying replenishment liquid into the coating tank. The level of the liquid surface 11 in the coating tank 1 rises, and the entry of air into the replenishment bottle is closed, so that the liquid in the bottle and the liquid in the coating tank are balanced and replenishment is stopped. In this way, the coating tank is in a state where the support 8 to be coated is not contained,
By keeping the level of the coating liquid constant, stable coating can be performed at all times. Also, if the inside of the coating tank is made of fluorine-based material,
This is effective because the liquid spreads well to the inner wall, making it difficult to form a film there. Furthermore, even if there is a slight amount of film or foreign matter mixed in, by forcing the circulation and filtering the coating solution as described above, it is possible to apply a coating with sufficient homogeneity to the support for practical purposes. Examples of the filter used in the method of the present invention include a mesh filter material made of metal such as stainless steel, paper, resin, and a sintered metal filter material, and the type of filter material is appropriately determined depending on the coating liquid and purpose. Further, the filter may be inserted at any position on the circulation pipe, but if the bottom of the coating tank is open between the pump and the pump, problems such as pressure reduction and generation of air bubbles will occur if the pump and the filter are open. Further, a pressure gauge may be provided between the pump and the filter to monitor the load and the state of filter clogging. Also,
Preferably, the filter can be removed and replaced.

【Effect of the invention】

By the method of the present invention, the coating liquid can be applied efficiently, uniformly, and stably to the outer peripheral surface of a cylindrical object without contaminating foreign matter or dust.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a block diagram of the #I2 embodiment of the present invention, Fig. 2-a is a partial top view of the same as above, and Fig. 3 is a A configuration diagram of an embodiment in which the replenisher supply device for the first and second embodiments is connected, and FIG. 4 is tJf.
Fig. 4 is a configuration diagram of another embodiment different from the third embodiment in which the replenisher supply device for the second embodiment is connected to the replenisher supply device for the second embodiment;
Figure a is a partial top view of the same as above. 1... Application tank 2... Replenishment tank P,... Pump P2... Pump 4... Circulation pipe 5... ... Filter 6 ... Replenishment pipe 7 ... Outer peripheral part 8 near the liquid level of the coating tank ...
・Support to be coated 9...Coating liquid 11...Liquid level in coating tank 11-a...Liquid level 1 when the support to be coated is immersed
2... Coating liquid level in automatic replenishment bottle 13...
... Refill port 14 ... Air reservoir 15 ... Automatic refill bottle

Claims (3)

[Claims] (1) A coating tank is filled with a predetermined amount of coating liquid, the coating liquid is extracted from the bottom of the coating tank using a pump, and the coating liquid is filtered through a filter again and returned to the liquid in the coating tank and forcedly circulated. A method of applying a coating agent to a cylindrical support, in which the cylindrical support to be coated is immersed in a coating liquid in a tank, and the coating is performed by relatively moving the coating tank and the cylindrical support. (2) Replenishment of the coating liquid that becomes insufficient due to coating on the substrate to be coated is performed by flowing the replenishing liquid tank to the front side of the filter for filtration. A method of applying a coating agent to a cylindrical support as described above. (3) Replenishment of the coating liquid that becomes insufficient due to coating on the support is carried out using a coating liquid automatic replenishment pin that has a supply port near the appropriate liquid level in the coating tank when the support is pulled out. A method for applying a coating agent to a cylindrical support according to claim 1.