JPS59139967A - Coating method - Google Patents

Abstract

PURPOSE:To inhibit the formation of unevenness in a coating film, in dipping a cylindrical workpiece to be coated in paint and then raising it, by providing an orbicular or conical body above an inflow opening for paint at the lower part of a coating tank to make the inflow stream of paint uniform. CONSTITUTION:A paint supply opening 1 is provided at the lower part of a cylindrical coating tank 2 to make a stream 7 directing upwards uniform. An orbicular 6 or conical body is provided at the position where said stream is not hampered, while directing its top end downwards, to let the stream 3 smoothly flow upwards along the inner wall of the tank 2. The paint having overflowed is recovered in a saucer 4 and recirculated through a pipe 5. Hereon, a cylindrical workpiece to be coated is dipped in the predetermined paint and then separated from the paint to form a predetermined coating film. Hence, the coating film having uniform film thickness free from unevenness can be formed. This method is applicable for manufacturing the photosensitive layer of a photosensitive body for electrophotography by coating.

Description

[Detailed description of the invention] The present invention relates to a coating method.

Dip coating is a widely used coating method in which the object to be coated is flattened in a V-shape and pulled up into a coating tank containing the paint. In this case, a container of any shape can be used as the coating tank.

The paint is placed in a coating tank, but it is also possible to keep the paint in the container, USP 2808344, USP 30461.
9. of paint as described in 56 etc. :In order to prevent unevenness and drying of the paint surface, it is better to allow the paint to overflow from the coating tank. Further, in this case, the unevenness of the coating film will be reduced if the paint is always supplied to the coating tank and the coating tank is constantly overflowed, rather than overflowing only when the object to be coated is immersed in the paint.

As a method for continuously supplying paint to the coating tank, it is reasonable to collect overflowing paint and send it again to the jibudan. The paint supplied to the coating tank flows into the coating tank from the supply port at a certain flow rate, but when the paint flows into the coating tank from the supply port in a flow rate, the paint 75
Electrical disturbances may cause the liquid surface of the paint to wave, causing unevenness in the paint film.For example, in the photosensitive layer of an electrophotographic photoreceptor, uniformity of film thickness is It is a very big problem to eliminate unevenness in j) and d:, which greatly contributes to photographic characteristics.

The main object of the present invention is to provide a coating method that can prevent the occurrence of unevenness in the coating film due to the disturbance of the state of the paint in the coating tank caused by the paint fed into the coating tank.

Value of this invention Cylindrical '$' in the paint! After soaking the coating,
In a coating method in which the paint is separated from the paint, a disk or cone is placed above the supply port to uniformize the flow of the paint flowing in from the supply port at the bottom of the coating tank. This is a percentage mark.

That is, the present invention is to gently change the flow direction in the coating tank so that the paint sent to the coating tank by the disc or the circular CF body does not flow straight into the coating area. The aim is to weaken the force of the inflow of paint, make the flow uniform, and prevent the paint from being disturbed. It is effective to prevent the paint stream from directly hitting the immersed object.

A specific method for changing the direction of liquid flow is shown in FIGS. 1 and 2. FIG. 1 is a plan view of a coating tank using the method trap of the present invention, and FIG. M2 is a side view thereof. Reference numeral 2 denotes a cylindrical coating tank, at the bottom of which a supply port 1 is provided through which the paint flows.

The reason why the water flows upward as indicated by arrow 7 is to make the flow more uniform than when it flows horizontally. The tray 4 is for collecting paint overflowing from the coating tank, which is discharged from a collection port 5 and circulated. 6 is a disk. This is done so as not to obstruct the flow of paint from supply port 1.
It is preferable that the distance be greater than the outer diameter of the supply port. However, it is not necessary to space them too far apart, and it is sufficient that the distance is equal to or smaller than the outer diameter of the coating tank. The size of the disk is preferably larger than the outer diameter of the object to be coated. By doing this, the supplied paint smoothly flows upward along the inner wall of the coating tank as shown by the arrow 5, so that no unevenness occurs. Note that when a cone is used instead of a disk, it is preferable to arrange the KFi cone so that its apex is on the lower side.

In FIG. 1, the lower part of the coating tank is shown to have a conical shape, but this is not limited to a conical shape, but may be flat or other shapes.

This coating tank is particularly effectively used when manufacturing a cylindrical electrophotographic photoreceptor by coating.

A detailed explanation will be given below using examples.

Example: Inner diameter 10 cn' as shown in Figures 1 and 2.
A cylindrical coating tank with a height of 35 cIrL was prepared, and the bottom was conical with an apex angle of 1400 mm, and a paint supply port was provided at the top. There is still a diameter of 5Crn on the 5CIn from the supply port.
A disc was installed. The cross-sectional area of the supply port is 1, 3 II
It is.

Next, 10 parts of a disazo pigment with the following structural formula (highlighted part, the same applies hereinafter) acetic acid ni' + acid "kuchi" R resin (commercial name: CAB-381)
;Eastman Chemistry! ! ! 6 BiL and 60 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1ψ glass beads. 100 parts of methyl ethyl ketone was added to this dispersion to prepare a paint.

This paint was poured at a flow rate of 0.7 mm using a magnetic pump, and the overflowing paint was collected in the pump again for circulation. Flow rate Id at the supply port 9. An aluminum cylinder with an outer diameter of 8 m and a length of 30 a + t, coated with 2 microns of casein, was immersed in this applicator, and then pulled up at a speed of 8 cm and 7 minutes. A layer of 0.08μ was formed, and the film thickness was uniform.
It was confirmed that there was no uneven color in the pigment layer.

On the other hand, when coating in a coating tank that does not have a disk, the inflowing liquid flows straight upwards because there is no disk, and it preferentially overflows, causing the liquid to flow upward. The paint was not mixed well with the liquid in the tank, and gradually unevenness of 1151 degrees occurred in the paint inside the coating tank. Therefore, unevenness occurred in the coating film.

Next, 10 parts of a hydrazone compound having the following structural formula and 15 parts of styrene-methyl methacrylate copolymer (trade name: MS-200, manufactured by Steel Manufacturing Chemical Exhibition) were mixed with 10 parts of toluene.
The solution was dissolved in 0 parts to give a paint, which was supplied and circulated through a coating device of the same shape at a flow rate of 0.44 parts. The flow rate at the supply port is 5. It was ICrrL/sec.

Using this coating device, a cylinder already coated with a pigment layer was immersed and pulled up by 6 cm at a speed of 1 minute to form a layer with a thickness of 15 μm. When the electrophotographic photoreceptor produced in this manner was taken into a specified electronic copying machine and a copy image was viewed, a good one was obtained. On the other hand, when the pigment layer had unevenness, the copied image also had 0 degree unevenness and was very difficult to see.

[Brief explanation of the drawing]

Figure 1 is a plan view of the coating tank used in the present invention, and Figure 2 is its 1111 side view. 1... Supply port 2... Coating tank 4... Receiver is plate 5... Collection port 6... Disc outlet person Canon Co., Ltd.

Claims (1)

[Claims] (i) In a coating method in which a cylindrical object to be coated is immersed in the paint and then partially released from the paint, the paint flowing in from the supply port at the bottom of the coating tank is placed on a circular plate or above the supply port. A coating method characterized by arranging cones to make the flow of incoming paint uniform during coating.