JPH0432706B2 - - 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
It is not suitable as a coating method for electrophotographic photoreceptors that require a coating amount 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.

In addition, the ring coating method uses only the coating liquid above the tip of the elastic ring, so the amount of coating liquid is small (on the other hand, as mentioned above, the contact time with the cylindrical body is short), and the amount of coating and the cylindrical shape There is a limit to the size of the body (outer circumferential area), and especially when coating a cylindrical body continuously, it is necessary to supply the coating liquid to the liquid container during coating.

However, whether the amount of coating liquid needed to coat one cylindrical object is supplied intermittently or continuously, it is difficult to control the level of the coating liquid at a constant level, and coating errors often occur. Therefore, liquid level control has become one of the extremely important issues in electrophotographic photoreceptors that require a highly uniform coating layer.

An object of the present invention is to solve the problems of the ring coating method as described above, to be able to continuously coat the outer circumferential surface of two or more coated substrates such as cylindrical bodies, and to always An object of the present invention is to provide a coating device that can obtain a uniform coating surface.

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 an apparatus for applying a coating liquid onto a circular outer peripheral surface of a substrate to be coated using a ring-shaped liquid container, in which a first substrate to be coated and a second substrate to be coated are joined. This has been achieved by a coating device characterized in that it is equipped with a means for enabling continuous coating even without the need for coating, and a means for allowing the coating solution to overflow from a coating solution surface of an arbitrary height.

That is, the present invention has a liquid reservoir for the coating liquid between the container outer cylinder and the container inner cylinder, the upper end of which is set lower than the container outer cylinder and has an elastic ring at the upper end. The elastic ring is configured to come into contact with the circumferential surface of a cylindrical body passing through the container, and the liquid level in the liquid reservoir is set higher than the upper end of the elastic ring to a predetermined height, and is provided above the container. The coating device is configured to apply a coating liquid to the circumferential surface of the cylindrical body while passing the cylindrical body upward using a first elevating device, the first lifting device having a first lifting device having a first elevation device. The height can be set by an overflow means provided in the container or in an external liquid storage tank communicating with the container, and the liquid in the liquid pool is A second cylinder is supplied from below the container by a second elevating device provided below the container so that the surface thereof is lower than the tip of the elastic ring so that the coating liquid does not leak into the inner cylinder of the container. Immediately after the shaped body is raised by the first lifting device and the upper end of the second cylindrical shaped body reaches a predetermined liquid level height during the coating, coating can be started at the liquid level height. The method is characterized by comprising means for making the liquid level in the liquid reservoir higher than the tip of the elastic ring so that the first and second cylindrical bodies can be continuously coated without joining them. It is a coating device that

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. FIGS. 2a and 2b are cross-sectional views showing an example of the ring-shaped liquid container 7 (including 6 and 8) in FIG. b shows the state in which the first cylindrical body is being coated, and b shows the state where the first cylindrical body has been coated. FIG. 3 is a sectional view showing another example of a ring-shaped liquid container.

In FIG. 1, the lifting devices 1 and 13 are provided with means for lifting and lowering at a constant speed. As for the means of raising and lowering, any known method may be used, such as a motor,
A hydraulic cylinder, pneumatic cylinder, etc. may be used.

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.
Limit switches, metal detection proximity switches, electrostatic switches, etc. are 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, the coating liquid is continuously supplied from the coating liquid supply pipe 8. As the coating progresses, when the cylindrical body 5 eventually blocks the light beam emitted from the light source 4, the detection device 3
works.

When the detection device 3 operates, the coating liquid level is adjusted to the tip of the elastic ring 71 so that the second cylindrical body 9 can be coated without spilling the coating liquid before the cylindrical body 5 comes out of the elastic ring 71. Means for lowering the temperature is activated. This method was introduced in 1978.
Patent application (2) was filed on February 20th,
172379), the elastic ring 71 and elastic ring support 72 as shown in FIG. Stop at any position higher than the liquid level (the first cylindrical body will come out as it is. Figure b) method, or Showa
Filed as a patent application on February 24, 1959
179171), there is a method in which a coating liquid discharge pipe 83 having a valve (electromagnetic valve) 82 as shown in FIG. Can be adopted.

Since the liquid level of the coating liquid is lower than the tip of the elastic ring 71, 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. In detecting this stop position, the detection device 10 operates when the cylindrical body 9 no longer blocks the light emitted from the light source 11, and the lifting operation of the lifting device 13 is stopped. At the same time, Rod 2 had finished ejecting and was descending.
The holder at the tip of the elastic ring 71 holds the cylindrical body 9 (not shown), and the detection device 10 operates in the opposite direction to the operation described for the detection device 3, so that the liquid level of the coating liquid is lower than the tip of the elastic ring 71. As a result, the coating liquid 74
comes into contact with the outer peripheral surface of the cylindrical body 9 and becomes ready for application.

By repeating the above operations, it becomes possible to continuously apply the material at intervals without joining the cylindrical objects. During this continuous coating, the coating liquid is continuously supplied from the coating liquid supply pipe 8.

In FIGS. 2 and 3, a ring-shaped liquid container 7
Separately, a liquid storage tank 84 is connected through a communication pipe 85 (also referred to as a coating liquid supply pipe), and this liquid storage tank 84 is provided with a coating liquid supply pipe 8 and an overflow pipe 81. Liquid storage tank 84 with overflow pipe 81
Providing the liquid container 74 separately from the liquid container 7 makes it easy to manufacture the device, and prevents local coating due to turbulence of the liquid surface caused by the flowing of the coating liquid 74 into the overflow pipe near the coating on the cylindrical body. Although it is necessary to prevent unevenness, if the outer diameter of the liquid container outer cylinder 73 is increased, a separate liquid storage tank can be eliminated.
An overflow pipe may be provided in the liquid container cylinder 73.

Coating onto the outer circumferential surface of the cylindrical body is performed at the liquid level of the coating liquid above the tip of the elastic ring 71, and the height of the liquid level can be set arbitrarily. In the coating device of the present invention, the height of the liquid level is determined by the overflow tube 81, but if the inlet of the overflow tube 81 is positioned slightly above the tip of the elastic ring 71, The operating distance of the elastic ring (Fig. 2) or the moving distance of the coating liquid level (Fig. 3) can be shortened, allowing continuous coating operations to be performed smoothly and accurately. Also suitable for high viscosity coating liquids. Moreover, although the coating liquid is continuously supplied from the coating liquid supply pipe 8 in an amount that is somewhat larger than the amount consumed (coated amount) by the cylindrical body, the liquid level of the coating liquid is also increased due to the movement of the cylindrical body. Since the coating does not change and can be coated under the same conditions at all times, it is possible to obtain an extremely uniform coated layer.

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, and coats a circular outer peripheral surface as a substrate to be coated. As long as it is a base material, it can be used for other purposes as well.

[Brief explanation of drawings]

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. FIGS. 2a and 2b are cross-sectional views showing one example of the coating apparatus of the present invention, and FIG. 3 is a cross-sectional view showing another example. 1, 13... Lifting device, 2, 12... Rod,
5, 9... Cylindrical body, 3, 10... Detection device,
4, 11...Light source, 7...Liquid container, 71...Elastic ring, 72...Elastic ring support, 73...
Liquid container outer cylinder, 74... Coating liquid, 75... Coating layer, 8... Coating liquid supply pipe, 81... Overflow pipe, 82... Valve, 83... Coating liquid discharge pipe,
6, 84...Liquid storage tank, 85...Communication pipe.

Claims (1)

[Claims] 1. A liquid reservoir for the coating liquid is provided between the container outer cylinder and the container inner cylinder, the upper end of which is set lower than the container outer cylinder and has an elastic ring at the upper end, and the elastic ring is The liquid level of the liquid reservoir is set higher than the upper end of the elastic ring to a predetermined height, and the liquid level of the liquid reservoir is set higher than the upper end of the elastic ring. The coating device is configured to apply a coating liquid to the circumferential surface of the cylindrical body while passing the cylindrical body upward using a lifting device, the coating device being configured to maintain a predetermined height of the liquid level during coating. This can be set by an overflow means provided in the container or in an external liquid storage tank communicating with the container, and the liquid level in the liquid reservoir section is set immediately before the end of application of the first cylindrical body passing through the container. a second cylindrical body that is lower than the tip of the elastic ring to prevent the coating liquid from leaking into the inner cylinder of the container, and is supplied from below the container by a second elevating device provided below the container; is raised by the first elevating device, and immediately after the upper end of the second cylindrical body reaches a predetermined liquid level height at the time of coating, coating can be started at the liquid level height, A coating characterized by comprising a means that allows the liquid level of the liquid reservoir to be higher than the tip of the elastic ring so that the coating can be applied continuously without joining the first and second cylindrical bodies. Device.