JPS6115767A - Method and apparatus for coating drum - Google Patents

Abstract

PURPOSE:To form a uniform coating layer to a drum, by contacting the open air flowed into a receiving tank with the solvent for a coating layer during a time when a coating drum is taken out of the receiving tank. CONSTITUTION:A solvent vapor replenishing means 2 is provided to the upper part in a coating solution receiving tank 1 and a drum 4 is received in the receiving tank 1 so as to hold a substantially air-tight state and immersed in the coating solution before taken out of the receiving tank 1. At this time, air is flowed into the receiving tank 2 in the amount corresponding to the volume taken out of the drum 4 but contacted with a solvent and saturated therewith. Therefore, the evaporation and drying of the coating solution are prevented and the concn. and viscosity of the coating solution is always held to a predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a drum dip coating method, and more particularly to a drum coating method and apparatus that can prevent evaporation of a coating liquid and maintain the coating liquid concentration at a predetermined level at all times.

(Prior Art) The method of coating a cylindrical drum with a coating liquid mainly includes a dipping method. However.

Since the solvent of the coating liquid is an organic solvent or the like and easily evaporates, the concentration and viscosity of the coating liquid constantly change. As a result, the coating layer of the resulting coated drum becomes non-uniform. For example, when such a drum is used as a photoreceptor for electrophotography, image unevenness, white spots due to pinholes, and background stains due to toner adhesion occur, making it impossible to provide clear electrophotographs.

In order to eliminate such defects, for example, as shown in FIG. It is proposed that However, this method is insufficient to prevent the solvent vapor 301 from flowing out of the storage tank 100.

In particular, when coating the drum 400 continuously,
As expected, evaporation of the coating liquid cannot be prevented. Furthermore, since the coating liquid 300 moves up and down the wall surface of the storage tank 100 as the drum 400 is taken in and out, the coating liquid 300 adhering to the wall surface dries and the resulting solids are mixed into the coating liquid 300. This also causes the coating layer to become non-uniform.

(Object of the Invention) An object of the present invention is to provide a drum coating method and apparatus that can maintain the concentration and viscosity of a coating liquid at a predetermined level at all times, thereby forming a uniform coating layer on a drum. . Another object of the present invention is to provide a drum coating method and apparatus that can perform coating simply and inexpensively using two mechanisms.

(Structure of the Invention) The coating method of the present invention is a method in which a drum is immersed in a coating liquid in a coating liquid storage tank and the coating liquid is applied to the drum. immersing the drum in a coating liquid in the storage tank while housing it in a tank and applying the coating liquid;
The method includes bringing the outside air flowing into the storage tank into contact with the coating liquid solvent in the upper part of the storage tank while the obtained coating drum is taken out of the storage tank, thereby achieving the above purpose. achieved.

The coating method of the present invention also includes heating the solvent in the upper part of the storage tank by a heating means.

This achieves the above objective.

Furthermore, there is a coating device for carrying out the above coating method.

An apparatus for applying a coating liquid to the drum by immersing the drum in the coating liquid in a coating liquid storage tank, and comprising a coating liquid storage tank and a solvent vapor replenishing means provided at the upper part of the storage tank. , the solvent vapor replenishing means accommodates the drum in the storage tank in a substantially airtight manner, and converts the outside air flowing into the storage tank into the vapor of the coating liquid solvent while the drum is taken out of the storage tank. The above object is thereby achieved.

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

For example, there is one coating device that can embody the method of the present invention.

As shown in FIGS. 1(a) and 1(b), it has a coating liquid storage tank 1 and a solvent vapor replenishing means 2 provided at the upper part of the storage tank 1. Solvent vapor supply means 2 is 1
For example, a ring-shaped lid 21 that is provided at the opening of the storage tank l and has a drum entrance/exit 211 in the center;
A solvent receptacle 22 is disposed along the inner circumferential surface of the storage tank 1 in a manner corresponding to the lid 21 at the lower part of the storage tank 1 .

Coating liquid solvent 3 accommodated in this solvent receiver 22
It becomes 1. The drum entrance/exit 211 of the ring-shaped lid 21 is
In order to allow the drum 4 to be taken in and out of the storage tank l in a substantially airtight manner, a gap 21 between the drum 4 and the drum 4 to be stored is provided.
It is configured so that 0 is maintained at an appropriate size.
Ventilation holes 212 of appropriate size are arranged in this lid 21 at appropriate intervals. The solvent receiver 22 has a gap 220 between the drum 4 to be accommodated and the lid 21 and the drum 4.
The gap 210 is larger than the gap 210 between the two. Therefore, the outside air flowing into the storage tank 1 from the first ventilation hole 212 comes into contact with the solvent 31 and saturates its vapor 310.
It can smoothly pass through this gap 220 and be replenished to the surface of the coating liquid 3. This is because the solvent 31 is volatile.

It constantly generates steam. This solvent vapor 310 has a specific gravity heavier than air. The solvent receiver 22 does not need to be provided all around the inner peripheral surface of the storage tank 1, and may be provided on at least a portion thereof.

The shape of the storage tank 1 is not particularly limited. Its volume is
In order to reduce the movement of the solvent vapor 310 and the coating liquid surface due to the loading and unloading of the drum 4, it is preferable that the volume is large relative to the external volume of the drum 4. Further, the material may be any material as long as it is insoluble in the coating liquid 3 8 Usually, aluminum, steel, synthetic resin, etc. are used.

The drum 4 for coating may be cylindrical or columnar;
There are no particular limitations on its length, cross-sectional area, thickness, material, etc. For example, in the case of a drum used for an electrophotographic photoreceptor, aluminum having a cylindrical shape is used.

The coating liquid 3 is applied to the drum 4 in the following manner. First, the drum 4 is inserted into the storage tank 1 from the drum entrance/exit 211 of the ring-shaped lid 21 arranged at the opening of the storage tank 1.
The container is housed in a substantially airtight manner. At this time, the same amount of gas as the external volume of the drum in the storage tank 1 passes through the gap 220 between the solvent receiver 22 and the drum 4 and passes through the lid ventilation hole 2.
12 to the outside of the storage tank 1. This drum 4 is then immersed in the coating liquid 3 in the storage tank 1. The obtained coating drum 4 is inserted into the entrance/exit 211 in the same manner as when it is stored.
The container is taken out of the storage tank 1 while maintaining a substantially airtight state with respect to the storage tank 1 with an appropriate gap 210.

At this time, the gas of the outside passenger volume in the drum 4 flows into the storage tank 1 from outside the storage tank 1 through the ventilation hole 212 .

The incoming air touches the solvent 31 in the solvent receiver 22 and generates solvent vapor 31.
0 and further passes through the gap 220 between the solvent receiver 22 and the drum 4 to reach the coating liquid level.

Therefore, a predetermined amount of solvent vapor 3 is constantly kept in the storage tank 1.
Evaporation of the solvent 31 of the coating liquid 3, which is filled with the coating liquid 3 and whose vicinity is saturated with the solvent vapor 310, is prevented. Although the wall surface of the storage tank 1 is wetted with the coating liquid 3 due to the rise and fall of the coating liquid level due to the dipping operation of the drum 4, this portion also does not dry. The coating layer of the coated drum thus obtained is uniform. Variations between lofts are also minimized. The ventilation hole 212 can also be provided on the side wall of the storage tank 1 above the solvent receiver 22.

The device of the present invention also has the features shown in FIGS. 2(al) and 2(b).
As shown in FIG.
For example, by providing a heating means 23 such as a heater, the solvent 31 can be forcibly evaporated and the above effects can be achieved even more effectively. The amount of evaporation of the solvent vapor 310 can be arbitrarily controlled by appropriately operating the heating means 23.

Thus, according to the above coating method and apparatus.

The necessary amount of solvent vapor 310 is automatically replenished to the coating liquid level in response to the loading and unloading of the drum 4.

The coating method and apparatus of the present invention are suitably used in fields where extremely fineness and high precision are required, such as the production of electrophotographic photosensitive drums, but they can of course be applied to other fields as well.

(Effects of the Invention) According to the present invention, the necessary amount of solvent vapor is automatically replenished into the coating liquid storage tank.

Evaporation and drying of the coating liquid is prevented, and the coating concentration and viscosity can be maintained at a predetermined level at all times.

By using a solvent vapor replenishment means accompanied by a heating means, the above effects can be achieved even more effectively. As a result, a uniform coating layer is formed on the outer peripheral surface of the drum. The equipment required for this has a simple configuration and the operation is not special, so coating can be performed at low cost. Continuous operation is also possible.

[Brief explanation of the drawing]

Fig. 1fa) and Fig. 1(b) are respectively a plan view and a front sectional view of main parts showing an example of a coating apparatus that can embody the coating method of the present invention, and Fig. 2 (al and bl are respectively A plan view and a front cross-sectional view of main parts showing another example of a coating device that can embody the coating method of the present invention. Fig. 3 is a front cross-sectional view of main parts showing an example of the prior art. 1.100... Coating liquid storage tank, 2... Solvent vapor supply means, 3,300... Coating liquid,
4,400...Drum, 21...Ring-shaped lid, 22
... Solvent receiver, 23 ... Heating means, 31 ... Solvent for coating liquid, 210, 220 ... Gap, 21
1...Drum entrance/exit, 212...Vent hole, 301
゜310...Solvent vapor. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A method of applying a coating liquid to the drum by immersing the drum in the coating liquid in a coating liquid storage tank, the method comprising: housing the drum in a substantially airtight manner in the storage tank; The drum is immersed in a coating liquid in the storage tank to apply the coating liquid, and while the obtained coating drum is taken out of the storage tank, outside air flowing into the storage tank is removed from the inside of the storage tank. A drum coating method comprising contacting an upper coating solution with vapors of a solvent. 2. The coating method according to claim 1, wherein the specific gravity of the solvent vapor is greater than that of air. 3. In the method of applying the coating liquid to the drum by immersing the drum in the coating liquid in the coating liquid storage tank, the drum is housed in the storage tank in a substantially airtight manner and the drum is placed in the storage tank. applying the coating liquid by immersing the drum in the coating liquid in the storage tank, bringing the obtained coating drum into contact with the vapor of the coating liquid solvent in the upper part of the storage tank, and heating the solvent in the upper part of the storage tank. A drum coating method comprising heating with. 4. The coating method according to claim 3, wherein the specific gravity of the solvent vapor is greater than that of air. 5. An apparatus for applying coating liquid to the drum by immersing the drum in the coating liquid in a coating liquid storage tank, comprising a coating liquid storage tank and a solvent vapor replenishment means provided at the upper part of the storage tank. , the solvent vapor replenishing means accommodates the drum in the storage tank in a substantially airtight manner, and converts outside air flowing into the storage tank into the vapor of the coating liquid solvent while the drum is taken out of the storage tank. a drum applicator configured to contact the drum; 6. The solvent vapor replenishing means includes a ring-shaped lid provided at the opening of the storage tank and having a drum entrance/exit in the center, and a ring-shaped lid provided at the lower part of the lid at least a part of the inner circumferential surface of the storage tank. A patent claim comprising: a solvent receiver provided along the inner circumferential surface; a coating liquid solvent accommodated in the solvent receiver; and a vent provided in at least one of the lid and the inner circumferential surface of the storage tank. The drum coating device according to item 5. 7. The drum coating device according to claim 6, wherein the solvent receiver has heating means. 8. The drum coating device according to claim 5, wherein the specific gravity of the solvent vapor is greater than that of air.