JPH02149366A - Overflow immersion coating device - Google Patents

Abstract

PURPOSE:To transfer quickly by providing an overflow coating liquid tank, a feeding tank, a coating liquid feeding pipeline and a coating liquid circulating line. CONSTITUTION:Coating liquid is transferred from a feeding tank 4 through a liquid feeding pipeline in a manner that photo sensitive liquid overflows all the time from the end surface of a coating liquid tank 1 to the side of a recovery tank 12. Then, a drum 3 is inserted into the coating liquid tank 1 and immersed. When the drum 3 is lifted up, coating is completed, and a following drum 3 is immersed. The overflowing coating liquid is so transferred as not to include foams through an overflow piping 8 and returns to the feeding tank 4. The photo sensitive liquid, therefore, circulates in a coating device system without including foams, and a good sensitizing treatment is provided all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a dip coating device having an overflow coating liquid tank, and in particular, to a dip coating device having an overflow coating liquid tank, and in particular, to transport a high viscosity liquid within the coating device system so as not to contain air bubbles inside the coating device system. The present invention relates to a dip coating apparatus having flexible piping.

(Prior Art) A coating liquid used in manufacturing an organic photoreceptor drum for an electrophotographic copying machine contains, for example, a charge-generating material and a charge-transporting medium as main components. The coating solution uses a volatile organic solvent such as tetrahydrofuran, and the photosensitive material is uniformly dispersed or dissolved in this organic solvent in a dispersion machine using an ultrasonic dispersion method, a ball mill method, a homomixer method, etc. After that, it is applied to the surface of the conductive substrate in an even thickness.

One method of applying a coating liquid to a substrate is to immerse the substrate into a coating liquid tank filled with the coating liquid and then pull it up.
There is a dip coating method in which a coating liquid is applied to the outer peripheral surface of a substrate. According to the dip coating method, it is necessary to frequently replenish the coating liquid, and simply pouring the coating liquid into the coating liquid tank from the top causes air bubbles to form on the liquid surface, resulting in uneven coating. Become.

In order to solve the above problems,
There is a publication. In this prior art, as shown in FIG. 5, the vicinity of the bottom of a coating liquid tank 90 and the vicinity of the bottom of an adjacent coating liquid storage tank 91 are connected by a pipe 92, and a section of the pipe 92 toward the coating liquid tank 90 is connected at an arbitrary point. It is equipped with an opening valve 93.

In this prior art, the coating liquid is supplied from the outside to the coating liquid storage tank 91 through a pipe 94 for replenishing the coating liquid.

The air bubbles generated during this replenishment float on the liquid surface, so
The coating liquid that passes through the pipe 92 communicating with the liquid does not contain air bubbles. Therefore, the coating liquid in the coating liquid tank 90 does not contain air bubbles, and the height of the liquid level in the coating liquid tank 90 can always be kept constant.

By the way, in the dip coating method, the solvent is constantly evaporated from the coating solution. As a result, a film is formed on the surface of the coating liquid tank containing the coating liquid due to evaporation of the solvent, and this film adheres to the circumferential surface of the substrate, resulting in uneven coating after the coating liquid dries.

Therefore, in order to eliminate the above drawbacks,
An immersion coating method has been proposed in which the coating solution always overflows from the upper end surface of the coating solution tank each time the photoconductor drum is immersed or during the process of manufacturing the photoreceptor drum.

In the overflow dip coating method, the coating solution is uniformly dispersed in a dispersion machine and transported to an overflow dip coating device via a pipe or the like. The coating apparatus system includes steps such as passing dust and lumps in the coating liquid through a filter while being supplied to an overflow coating liquid tank within the coating apparatus system.

(Problems to be Solved by the Present Invention) In the coating apparatus system as described above, a coating liquid circulation pipe is provided to collect the coating liquid that overflows from the coating liquid tank and re-supply it to the coating liquid tank. It is included in the coating equipment system.

When recovering overflowing coating liquid, it is common to provide an annular recovery tank around the outer periphery of the coating liquid tank.

When the coating liquid recovered from the recovery tank is returned to the supply tank via the circulation pipe, the coating liquid comes into contact with the outside in the coating apparatus system, which is isolated from the outside. When the coating liquid is transported, bubbles are generated due to the flow caused by the transport of the coating liquid, and these bubbles become air bubbles and are contained within the coating liquid. Therefore, in order to eliminate the air bubbles, either the coating liquid is temporarily stored and the liquid is waited for the air bubbles to disappear, or the stored coating liquid is supplied from inside the liquid to the coating liquid tank as in the prior art described above. However, if the coating liquid has a high viscosity, it will take much time, so it is preferable to prevent the coating liquid from flowing as much as possible during transport.

Furthermore, even if the piping is tilted and the coating liquid is returned to the supply tank, if the dipping speed of the substrate is increased and the coating process time is shortened, the force with which the overflowing coating liquid is transported through the piping will increase, which will solve the above problem. have not yet been resolved.

When such a coating liquid is supplied to a coating device, specifically a coating liquid tank in a dip coating method, and the substrate is immersed and pulled up to apply a photosensitive substance to the outer peripheral surface of the substrate, air bubbles mixed in the coating liquid are removed. However, as the coating solution dries, the coating becomes uneven (bumps on the coating).

When such a photosensitive drum is used in a copying machine,
The paint film is likely to peel off and its durability is significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to transport a high viscosity liquid such as a photosensitive liquid through a coating apparatus system using a tubular body when manufacturing a photosensitive drum using an overflow coating liquid tank. In this case, an overflow dip coating device is provided which allows rapid transportation without creating bubbles.

(Means for Solving Problems) According to the present invention, there is provided an overflow coating liquid tank in which a coating liquid is applied to a substrate in a coating liquid tank, and a supply tank that stores a coating liquid to be supplied to the coating liquid tank. a coating liquid supply pipe that transports the coating liquid from the supply tank to the coating liquid tank; and a coating liquid circulation pipe that has a spiral overflow pipe that circulates the coating liquid overflowing from the coating device to the supply tank. There is provided an overflow dip coating apparatus comprising: a coating liquid flowing out from the overflow pipe; the coating liquid flowing out from the overflow pipe being temporarily stored and supplied to the coating liquid tank;

Further, according to the present invention, there is provided an overflow coating liquid tank for applying a coating liquid to a substrate in a coating liquid tank, a supply tank for storing a coating liquid to be supplied to the coating liquid tank, and a supply tank for storing a coating liquid to be supplied to the coating liquid tank, and a supply tank for storing a coating liquid to be supplied to the coating liquid tank; A coating liquid circulation pipe having a coating liquid supply pipe for transporting the coating liquid to the tank, and an overflow pipe that is inclined and widens toward the tip for circulating the coating liquid overflowing from the coating device to the supply tank. An overflow dip coating apparatus is provided, which is characterized in that the coating liquid flowing out from the overflow pipe is temporarily stored and supplied to the coating liquid tank, thereby achieving the above object.

(Function) According to the above configuration, the supply tank meets the coating liquid supply pipe line and supplies the coating liquid to the overflow coating liquid tank. The overflow coating liquid tank applies a coating liquid to the surface of the substrate by immersing the substrate.

At this time, the overflowing coating liquid is collected and the force of transport is reduced by the spiral overflow piping in the coating liquid circulation line. Then, after being temporarily stored, it is again supplied to the overflow coating liquid tank.

According to another configuration of the present invention, the overflowing coating liquid is collected and the force of transportation is reduced by the overflow piping which is inclined in the coating liquid circulation pipe and widens toward the tip.

(Example) Examples of the coating liquid transported by the overflow dip coating apparatus of the present invention include photosensitive liquids used in electrophotographic organic photoreceptors. The photosensitive liquid contains, for example, a charge-generating pigment and a charge-transporting medium as main components. As the charge-generating pigment, for example, a photoconductive organic pigment such as a perylene pigment or a quinacridone pigment is used. As the charge transport medium, for example, a charge transport resin such as polyvinylcarbazole is used. In addition, a solvent such as tetrahydrofuran, a sensitizer such as a dye, or a leveling agent such as silicone oil is appropriately used in the photosensitive solution.

After each of the above components is measured in a predetermined amount, it is supplied to a dispersion machine and uniformly dispersed. The disperser does not need to be special;
Dispersing machines commonly used in this field are appropriately used. Examples include stainless steel ball mills, homomixers, or ultrasonic dispersers.

The uniformly dispersed photosensitive liquid is then transported through an overflow dip coater system embodying the present invention.

Examples of the present invention will be described below.

The overflow dip coating device of the present invention accommodates a photosensitive liquid as shown in FIG.
A plurality of overflow coating liquid tanks 1 (only one is shown in FIG. 1) for overflowing the photosensitive liquid, a tank liquid block 2 for branching and supplying the coating liquid to each of the plurality of coating liquid tanks 1, and In order to supply the photosensitive liquid to the coating liquid tank 1 via the tank liquid block 2, there is a supply tank 4 in which the photosensitive liquid after dispersion is stored, and a supply tank 4 in which the photosensitive liquid overflowed from the coating liquid tank 1 is temporarily stored. It consists of a cushion tank 5 which is later supplied again to the supply tank 4. The supply tank 4 and the tank liquid block 2 are connected to each other by a tubular body 7o such as a conveying pipe to transport the photosensitive liquid stored in the supply tank 4.

In addition, within the path of the tubular body 70, pumps 71. A filter 72 and a pump 7374 are provided.

Note that any pump such as a magnetic pump, gear pump, diaphragm pump, or screw pump may be used. As the tubular body, for example, a conveying pipe made of synthetic resin, rubber, or metal, which is normally used in this field, is appropriately used. Its diameter and length are appropriately set depending on the purpose.

Reference numeral 3 denotes a cylindrical photosensitive drum base (drum l), which is held by a holding means (not shown) disposed above the coating liquid tank 1. As shown in FIG. The holding means is disposed approximately vertically above the coating liquid tank 1, and its upper part is connected to an elevating device (not shown), and the elevating device allows the holding means to move up and down while maintaining the drum 3 in a substantially vertical state. Driven. Incidentally, as the above-mentioned holding means, for example, the one disclosed in Japanese Patent Application Laid-Open No. 61-25660 can be used. Therefore, the drum 3 is hollow and can be immersed without allowing the photosensitive liquid to enter inside.

Further, the drum 3 is made of aluminum, for example.

Cylindrical or foil metals such as nickel, copper, zinc, palladium, silver, indium, tin, platinum, iron, stainless steel, and brass are used. Note that the cylindrical shape of the tram 3 means that the shape of both ends is not particularly limited as long as at least the body part is cylindrical. or a portion may be added.

The supply tank 4 consists of a container, and the photosensitive liquid is fed into the interior through an inlet 43.
Supplied from. A plurality of blades 42 attached to a rotating shaft 41 are provided inside the supply tank 4, and the blades 42 rotate at high speed to agitate the photosensitive liquid in the supply tank 4. The photosensitive liquid after stirring flows out from the outlet 44. and pump 7
1 is driven, and the photosensitive liquid filtered through the filter 72 flows through the tubular body 70 into the tank liquid block 2 by pumps 73 and 74.

The photosensitive liquid that comes out of the dispersion machine contains pulverized dispersion medium and undispersed coarse particles. Difficult to use. Therefore, the filter 72 may have a mesh that does not allow passage of particles coarser than the thickness of the film to be coated, but preferably the mesh is finer than the film thickness and larger than the pigment particles.

The tank liquid block 2 consists of a sealed container, and has a tubular body 70.
It has a plurality of smaller diameter branch pipes 21 (only one is shown in the first article). The photosensitive liquid flows into the tank liquid block 2,
After the interior is filled, the photosensitive liquid flows out from each branch pipe 21. A coating liquid tank 1 is provided at the end of each of the branch pipes 21.
are provided to guide the photosensitive liquid supplied from the supply tank 4 into the respective coating liquid tanks l.

As described above, the area from the supply tank 4 to the tank liquid block 2 constitutes a coating liquid supply pipe line.

The coating liquid tank 1 consists of a tank body 11 containing a photosensitive liquid, and a recovery tank 12 provided around the outer periphery of the tank body 11. Although the shape of the tank body 11 is not particularly limited, it is preferably a cylindrical container, and has an inner diameter larger than the outer diameter of the drum 3 and a depth larger than the axial length of the drum 3. have. The recovery tank 12 is formed so that the outer periphery of the upper edge of the tank body 11 is annular, an opening is provided in a part of the outer wall of the recovery tank 12, and an overflow pipe 8 is connected to the opening 5 to form a cushion tank 5. is connected to. Therefore, branch pipe 21 from tank liquid block 2
The photosensitive liquid flows into the coating liquid tank 1 through the coating liquid tank 1, and the photosensitive liquid overflowing from the coating liquid tank 1 is once collected in the recovery tank 12, and then flows into the cushion tank 5 through the overflow pipe 8.

The overflow pipe 8 has a tubular body formed in a spiral shape, and cushions the shock when the photosensitive liquid flows into the cushion tank 5. That is, the resistance to the photosensitive liquid increases as the photosensitive liquid is transported in a spiral pattern, and the impact and ripples when it flows into the photosensitive liquid in the cushion tank 5 are alleviated, thereby preventing the formation of bubbles.

The cushion tank 5 is used to temporarily store the amount of photosensitive liquid overflowing from the coating liquid tank 1 and return it to the supply tank 4, thereby supplying the photosensitive liquid to the tubular body 61 without containing air. . The cushion tank 5 has a large diameter -F for receiving the end of the overflow pipe 8.
part 51 and a conical lower part 5 mainly for storing the photosensitive liquid.
Consists of 2. A wall 53 is provided above the lower portion 52 and has approximately the same diameter as the lower portion 52, and a detecting means 54 for detecting the amount of photosensitive liquid stored in the cushion tank 5 is also provided.

The detection means 54 is comprised of a ring-shaped float made of a lightweight member (eg, styrene foam, etc.) that can float above the surface of the photosensitive liquid. An optical sensor or the like detects that the float moves up and down as the surface of the photosensitive liquid rises and falls, and when the float reaches a certain height, the pump 62 operates to supply the photosensitive liquid to the tank 4 through the tubular body 61. Reflux to. In a specific example, the detection means 54 adjusts the liquid level in the cushion tank 5 to a height such that the opening at the end of the overflow pipe 8 is not completely immersed in the photosensitive liquid at all times or when the liquid level changes.

The wall 53 acts to prevent the float from swinging when the liquid level in the cushion tank 5 is rippled due to the photosensitive liquid flowing in from the overflow pipe 8. Therefore, the float moves up and down only as the liquid level rises and falls, and the height of the liquid level can always be accurately detected.

By temporarily storing the photosensitive liquid in the cushion tank 5, even if the photosensitive liquid contains bubbles, the photosensitive liquid below the liquid without bubbles can be sequentially returned to the supply tank 4. Since the cushion tank 5 is provided, when the photosensitive liquid has a high viscosity, it takes time for bubbles to disappear, but since the photosensitive liquid without bubbles can be refluxed into the supply tank 4, of photosensitive liquid can be supplied in a short cycle.

The cushion tank 5 and the supply tank 4 have a tubular body 60.
and a pump 61 is provided.

As described above, the portion from the overflow pipe 8 to the supply tank 4 through which the recovered photosensitive liquid is circulated constitutes a coating liquid circulation pipe.

In addition, 200 is a valve, which is provided in the coating liquid supply pipe and the coating liquid circulation pipe when the photosensitive liquid is circulated for the first time in the coating apparatus system. It is used to remove air from the body.

In the above configuration, the present invention is implemented as follows.

First, the coating liquid is transported from the supply tank 4 through the coating liquid supply conduit and flows in so that the photosensitive liquid constantly overflows from the upper end surface of the coating liquid tank 1 to the recovery tank 12 side. Next, the drum 3 is inserted into the coating liquid tank 1 and immersed. When the drum 3 is pulled up, coating is completed and the next drum 3 is dipped.

The overflowing coating liquid is transported through an overflow pipe 8 without containing air bubbles, and is returned to the supply tank 4. Therefore, the photosensitive liquid circulates within the coating device system without bubbles, and a good photosensitive drum is always manufactured.

Other embodiments of the present invention are shown in FIGS. 2 and 3.

As shown in FIGS. 2 and 3, the shape of the overflow pipe 81 in this embodiment is different from that in the previous embodiment.

The overflow pipe 81 is gently sloped near the tip connected to the cushion tank 5, and has an opening 82.
spreads out toward the tip.

Therefore, the photosensitive liquid recovered from the coating liquid tank 1 becomes thinner as it goes to the cushion tank 5. Therefore, the impact on the photosensitive liquid stored in the cushion tank 5 is alleviated.

FIG. 4 shows yet another embodiment. In the overflow pipe 83 of this embodiment, the opening 84 has a long elliptical shape, and the photosensitive liquid flows out in the form of thin waves.

In the above embodiment, a configuration in which a cushion tank 5 for temporarily storing the photosensitive liquid is provided in the coating liquid circulation path has been described, but the cushion tank 5 can be used if the coating device system itself can be laid out in a vertically long configuration. There's no particular need.

(Effects) As described above, according to the present invention, in the overflow dip coating apparatus, the pipe is spirally or inclined in shape and expands toward the tip to transport the overflow coating liquid, so that the overflow coating liquid is transported. By reducing the force of the liquid, it is possible to suppress the flow of the coating liquid and the generation of bubbles due to ripples.

Therefore, the speed of the dipping process can be increased and the manufacturing process can be made into a short cycle, which is a special effect.

Furthermore, even if the speed of the dipping process is not increased, when the number of coating liquid tanks is increased, a large amount of coating liquid will be recovered. Even in such a case, the generation of bubbles can be suppressed.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of an overflow dip coating apparatus according to the present invention, Fig. 2 is a schematic diagram showing another embodiment of the invention, and Fig. 3 shows a part of the overflow piping shown in Fig. 2. FIG. 4 is a perspective view of a main part showing a part of an overflow pipe according to still another embodiment of the present invention, and FIG. 5 is a side sectional view showing a conventional technique.

Claims (2)

[Claims] (1) An overflow coating liquid tank that applies a coating liquid to a substrate in the coating liquid tank; a supply tank that stores the coating liquid to be supplied to the coating liquid tank; and a supply tank that supplies the coating liquid from the supply tank to the coating liquid tank. a coating liquid supply pipe for transporting the coating liquid, and a coating liquid circulation pipe having a spiral overflow pipe for circulating the coating liquid overflowing from the coating device to the supply tank, the coating liquid flowing out from the overflow pipe. An overflow dip coating apparatus characterized in that a liquid is temporarily stored and then supplied to the coating liquid tank. (2) An overflow coating liquid tank that applies a coating liquid to a substrate in the coating liquid tank; a supply tank that stores the coating liquid to be supplied to the coating liquid tank; and a supply tank that supplies the coating liquid from the supply tank to the coating liquid tank. a coating liquid supply pipe that transports the coating liquid; and a coating liquid circulation pipe that has an inclined overflow pipe that circulates the coating liquid overflowing from the coating device to the supply tank and that widens toward the tip. An overflow dip coating apparatus characterized in that the coating liquid flowing out from the overflow pipe is temporarily stored and supplied to the coating liquid tank.