JPS634463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for coating the outer surface of a cylindrical body such as a photoreceptor drum for electrophotography, and particularly relates to an apparatus for coating the outer surface of a cylindrical body such as a photoreceptor drum for electrophotography, and particularly for forming a coating film uniformly and extremely thinly. The present invention relates to a coating device.

Prior Art Conventionally, methods for coating a cylindrical body with a coating material include a spray method, a dipping method, and a vertical coating method in which an annular liquid container is provided outside the cylindrical body and either the cylindrical body or the liquid container is moved to apply the coating material. The membrane method is known. Although the spray method is excellent in mass production, it has the drawbacks of a small amount of coating per application and poor surface smoothness. The dipping method is a simple method, but sagging causes a difference in film thickness between the upper and lower parts, and when coating two or more layers, if each layer is coated with the same solvent system, the lower layer may be damaged. There are drawbacks such as.

The vertical coating method has the advantage that, compared to the above two methods, the surface smoothness of the coating film is excellent and the contact time with the coating liquid is short, so multilayer coating is possible using the same solvent system. However, if the liquid container and the cylinder are in contact with each other when coating, there are disadvantages in that if a highly viscous coating liquid is used, air bubbles are likely to be drawn in, and in the case of multilayer coating, there is a possibility of scratching the lower layer. To overcome this drawback, a non-contact vertical movement coating method is known in which the inner diameter of the liquid container is larger than the outer diameter of the cylindrical body. When the cylinder body and the liquid container are stopped relative to each other, the coating liquid may drip from the gap between the cylindrical body and the liquid container. The problem is that the viscosity of the coating liquid that can be used is considerably limited depending on the viscosity of the coating, and that only high-viscosity coating liquids can be used.

Purpose of the Invention Therefore, the purpose of the present invention is to solve the above-mentioned problems and to provide a method for forming a coating film on the outer surface of a cylindrical body.
To provide a coating device capable of producing a multilayer coating with good surface smoothness, free from scratches and bubbles, and capable of coating a coating liquid in a wide range of viscosity.

Composition of the Invention In order to achieve the above object, the vertically movable coating device according to the present invention has a coating liquid container that is an annular coating liquid container that surrounds the outer surface of the cylindrical body, or a cylindrical body that has an annular coating liquid container that is stopped relative to the cylindrical body. The container is characterized in that the container and the cylindrical body are in contact with each other when the container and the cylindrical body are moving, but a means is provided to bring them into a non-contact state when they are moving relative to each other.

Embodiments Examples of the present invention will be described below with reference to the drawings while comparing them with a conventional non-contact vertical movement type coating device.

First, an example of a conventional non-contact vertical movement type coating device will be explained with reference to FIGS. 1 and 2. Cylindrical body 1
An annular liquid container 2 surrounding the cylindrical body 1 is installed on the outer surface of the cylindrical body, and a coating liquid is supplied to the annular liquid container 2.
By moving vertically from bottom to top at a constant speed, a coating 3 of a constant thickness is applied to the outer surface of the cylindrical body 1. This method is good when the viscosity of the coating liquid is high, but when the viscosity of the coating liquid is low, as shown in Figure 2,
When the cylindrical body 1 is stopped, the coating liquid drips 4 and cannot be used.

In the coating device of the present invention, when the cylindrical body 1 and the annular liquid container 2 are relatively stationary, they are in contact with each other, and when both are moving vertically relative to each other,
It has a means for bringing the two into a non-contact state. A specific example of means for creating such a contact state and a non-contact state between the cylindrical body 1 and the annular liquid container 2 will be explained with reference to FIGS. 3, 4, and 5. One method is to attach an elastic tube 5 to the lower part of the annular liquid container 2, as shown in FIG. , the cylindrical body 1 and the container 2 are in contact or in a non-contact state, and as another method, as shown in FIG. An auxiliary cylindrical body 6 having an outer diameter larger than the body is installed, and a state of contact with the container 2 is created here.

By this means, when the cylindrical body 1 moves vertically from the bottom to the top, it is kept in a non-contact state, and a very small thickness is applied to the outer surface of the cylindrical body 1, similar to the conventional vertical type coating device (FIG. 1). For example, a film with a constant thickness of several microns to several tens of microns can be applied. Further, when the cylindrical body is stopped due to supply of coating liquid, etc., a contact state is created as shown in FIGS. 4 and 5. That is, during the stoppage, the liquid container 2 is in contact with the cylindrical body 1, so that dripping 4 as shown in FIG. 2 does not occur. Note that the means for creating a contact state and a non-contact state between the cylindrical body 1 and the liquid container 2 are not limited to the above two examples, and the means for creating a contact state and a non-contact state between the cylindrical body 1 and the liquid container 2 is not limited to the above two examples. Alternatively, a rubber ring or the like that can be automatically attached and detached may be attached to the cylindrical body or container; any means may be used as long as it can create a contact state and a non-contact state.

Furthermore, the material of the liquid container used in the coating device of the present invention may be any material as long as it is not corroded by the coating liquid, and in addition to Teflon-based materials, commonly used plastics such as polystyrene, polypropylene, polyvinylidene fluoride, etc. Metals such as Al and stainless steel, rubber materials, etc. can be used.

As shown in FIG. 3, the apparatus of the present invention can be manufactured by coating an aluminum pipe (outer diameter 120 mm) as a cylindrical body 1 with the following coating liquid using an annular liquid container 2 with a tube 5 attached. We confirmed the effectiveness.

Coating liquid: polycarbonate resin with methylene chloride/
A resin solution having a viscosity of 30 c.p. was prepared by dissolving it in a 9/1 ratio of 1,1,2-trichloroethane.

First, the tube 5 was filled with air and brought into contact with the aluminum pipe 1, and the coating liquid was supplied to the annular liquid container 2. At the same time as removing the air from tube 5, the aluminum pipe was moved vertically from bottom to top at 600 mm/min to form a coating film on the aluminum pipe. After drying at 80° C. for 1 hour, a film with excellent surface smoothness was obtained.

Next, as a comparative example, an attempt was made to apply the coating liquid onto the aluminum pipe using a conventional annular liquid container 2 as shown in FIG. Although the coating liquid was supplied to the liquid container with the aluminum pipe stopped, the coating liquid immediately flowed out from the gap between the liquid container 2 and the aluminum pipe, and normal coating could not be performed. At this time, as shown in Fig. 6, the width h of the gap between the liquid container 2 and the aluminum pipe as the cylindrical body 1 is 0.5 mm, and the vertical length i of the gap is 5 mm.
It was hot.

Effects of the Invention As described above, in the coating device of the present invention, which creates a contact state when the cylindrical body and the annular liquid container are relatively stationary, even when both are relatively stationary, the contact state is maintained. , since it can prevent sauce,
It can be used without any problems even if the viscosity of the coating liquid is low, and therefore has the advantage that it has good surface smoothness, can create a multilayer coating without scratches or bubbles, and has a wide range of viscosity. Therefore, the coating apparatus of the present invention is particularly suitable for applications such as electrophotographic photoreceptors, which require a wide range of film thickness from several microns to several tens of microns, and must also ensure uniformity of the coating film. It is valid.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing a conventional non-contact vertical movement type coating device, FIGS. 3 and 4 are block diagrams showing an example of a coating device according to the present invention, and FIG. 5 is a block diagram showing an example of a coating device according to the present invention. FIG. 6 is a diagram showing the relationship between the gap between the cylindrical body and the container of the conventional device. 1...Cylindrical body, 2...Annular liquid container, 3...Coating film, 4...Sag, 5...Elastic tube, 6...Auxiliary cylindrical body.

Claims (1)

[Claims] 1. In an apparatus for storing a coating liquid in an annular liquid container surrounding the outer surface of a cylindrical body and coating the outer surface of the cylindrical body by moving the cylindrical body and the liquid container relative to each other in a vertical direction, The liquid container or the cylindrical body is provided with means for bringing the container and the cylindrical body into contact when the container is stationary relative to the cylindrical body, but removing that contact when the two are moving relative to each other. A cylindrical coating device featuring: