JPS6221341Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a liquid-draining coating device for applying coating liquid to the surfaces of base materials such as various lenses and reflecting mirrors.

Conventionally, polymer solutions and the like have been applied as coating liquids to the surfaces of glass or plastic substrates such as eyeglass lenses, prisms, and medical parts for the purpose of improving surface hardness, imparting weather resistance, or antifogging properties. , I'm trying to burn this in.
Brush coating, roller coating, spray coating, electrostatic coating, flow coating, barrel coating, and dipping coating are generally known as coating methods. Of these, dipping coating is easier to use and provides a better coating film. It is widely used because it has excellent uniformity.

In such dip coating, the substrate is immersed in a tank filled with a coating solution, and then either the substrate is pulled upwards or the tank itself is lowered. As a result, vibrations occur when lifting the substrate or lowering the tank, and due to the influence of this vibration,
There were problems such as micro-movement propagating to the contact boundary between the substrate and the coating liquid, and the coating liquid not being applied to a uniform thickness.

For this reason, the present applicant has previously proposed a coating method using a drain type coating device as shown in FIG. 1 in Japanese Patent Publication No. 55-3019.

Such a coating device has a structure in which a sub-tank 2 is disposed below a main tank 1 that performs the coating process, and the lower end of a coating liquid drain pipe 3 that hangs down from the bottom of the main tank 1 faces into the sub-tank 2. With the opening/closing knob 4 provided in the liquid drain pipe 3 closed, the adjustment valve 5 is set to an appropriate opening degree, and after filling the main tank 1 with the coating liquid 6, the base material 7 is suspended and supported in the main tank 1. The main tank 1 is immersed in the coating liquid 6, and then the opening/closing pot 4 is opened.
The coating liquid 6 in the main tank 1 is drained into the sub-tank 2, and the liquid level of the coating liquid 6 in the main tank 1 is gradually lowered, and as the liquid level falls, the coating liquid is applied to the base material 7. This is what I did.

However, in the case of the above-mentioned liquid drain type coating device, in order to uniformly apply the coating liquid to the surface of the substrate, the liquid level must be lowered at a very slow speed of, for example, about 2 cm/min. Moreover, the coating liquid itself is extremely viscous.
Therefore, if the shape of the main tank is made into a shape having corner portions such as a rectangular planar shape in view of storage of the base material, etc., a retention portion of the coating liquid will occur at the corner portion. When a stagnation area occurs, separation of the coating liquid occurs in this area, and
This appears as surface defects after baking.

The present invention was made to improve the above-mentioned problems, and its purpose is to prevent the coating liquid from forming a stagnation part in the main tank in which the coating process is applied to the base material. To provide a liquid drain type coating device which can prevent separation of a coating liquid, can uniformly apply the coating liquid to the surface of a substrate, and can prevent surface defects from occurring.

In order to achieve the above object, the liquid-draining coating device according to the present invention has a main tank for coating a base material having a corner portion, and a sub-tank disposed below at the bottom of the main tank for coating the base material. The gist is that a main liquid drain pipe for discharging liquid is connected, and an auxiliary liquid drain pipe is provided on the side wall of the main tank forming the corner portion.

An example of the implementation of the present invention will be described in detail below based on the accompanying drawings.

FIG. 2 is a cross-sectional view showing the schematic structure of the coating device according to the present invention, and shows the coating device 10.
has 11 main tanks at the top and 1 sub tank at the bottom.
2 are installed respectively. Main tank 11 is the third
As shown in the figure, it has a substantially rectangular shape in plan view with corner portions 13 at its four corners, and the coating liquid 14 is applied to the upper end of the rectangular shape when the coating liquid 14 overflows.
Grooves 15 are formed for effectively discharging air bubbles inside. A float switch 16 is disposed within the main tank 11 to detect the level of the coating liquid 14.

Further, a hakama-shaped extension wall portion 17 is integrally provided hanging from the side wall 11a of the main tank 11. This extension wall portion 17 is for allowing the coating liquid 14 overflowing from the upper end of the main tank 11 to smoothly flow down into the sub-tank 12, and its upper end coincides with the lower end of the groove portion 15 or is located below it. The lower end faces into the sub-tank 12.

Furthermore, as shown in FIG. 4, a side wall 11a forming a corner portion 13 of the main tank 11 is provided with a sub-liquid drain pipe 18, which is a main part of the present invention, at a position slightly above the tank bottom surface 11b. This auxiliary liquid drain pipe 18 is provided with a valve 19 for liquid drain adjustment in the middle, and is bent at the lower part, and has the extension wall 17
The lower end is located close to. By keeping the valve 19 open at all times, the coating liquid 14 in the main tank 11 flows from the lower end of the liquid drain pipe 18 to the surface of the extension wall 17 and into the sub tank 1.
Flows down into 2. Here, the reason why the sub-liquid drain pipe 18 is placed slightly above the bottom surface 11b is because the main tank 1
This is to prevent air bubbles from being generated when the coating liquid is supplied by not completely emptying the inside of the tank 11 by draining the liquid, but leaving a small amount of coating. A sub-liquid drain pipe 18 may be provided at the height. On the other hand, the inside of the sub-tank 12 is divided into an outer chamber 20 and an inner chamber 21 by the extension wall 17, and these chambers 2
0, 21 are the lower end of the extension wall 17 and the sub tank 1
It communicates with the bottom surface of 2, and this communication part has a
A partition member 22 made of wire mesh or the like having 25 to 200 meshes, preferably 50 to 100 meshes, is provided to separate the outer chamber 2.
Air bubbles 23 in the coating liquid inside the inner chamber 21
I try not to get inside. Furthermore, a chiller 24 is provided in the outer chamber 20 of the sub-tank 12 to lower the temperature of the coating liquid 14 to keep the viscosity of the coating liquid constant, and a coating liquid replenishment part 25 is provided on the outer wall of the sub-tank 12. ing.

Next, to explain the piping system of the coating device 10, a main liquid drain pipe 26 for the coating liquid is connected to the bottom of the main tank 11, and this main liquid drain pipe 26 is branched into pipes 26a and 26b in the middle, and one 26a is provided with a liquid drain adjustment valve 27, and the other 26b is provided with a rapid liquid drain valve 28, and the respective pipes 26a, 26b are connected to the replenishment section 25. A coating liquid discharge pipe 29 is led out from the bottom of the inner chamber 21 of the sub-tank 12, and a pump 31 driven by a motor 30 is installed in this discharge pipe 29, and the coating liquid 14 is taken out by this pump 31. The coating liquid is sent to a filter 32 for cleaning. The pipe 33 on the downstream side of the filter 32 branches in the middle, one 34 is connected to the inner chamber 21 of the sub-tank via an opening/closing cock 35 in the middle, and the other 36 has an opening/closing cock 37 and a check valve 38 in the middle. The pipe is connected to the bottom of the main tank 11 through the pipe, and serves as a supply pipe for the coating liquid.
A partition member 39 similar to the partition member 22 is provided on the supply pipe 36 facing into the main tank 11 to prevent the liquid level in the main tank 11 from fluctuating.

Coating device 10 configured as above
The effect of this is described above.

First, after suspending and supporting the substrate in the main tank 11 which is not filled with coating liquid, the opening/closing pot 35 is closed, the opening/closing pot 37 is opened, and the coating liquid is supplied to the main tank 11 through the supply pipe 36.
supply within.

Then, after letting the coating liquid overflow from the upper end of the main tank 11 for a while to make the coating liquid in the main tank free of air bubbles,
The opening/closing knob 35 is opened, the opening/closing knob 37 is closed,
At the same time, the liquid drain adjustment valve 27 is opened by a predetermined amount, and the liquid is connected to the main tank 11 via the main liquid drain pipe 26.
Drain the coating liquid inside. Then, the liquid level of the coating liquid gradually falls, and as it does so, the coating liquid is applied to the surface of the substrate at a constant thickness.
When the coating liquid falls further and the float switch 16 senses that the liquid level of the coating liquid has passed the lower end of the substrate, the rapid liquid drain valve 28 opens and the coating liquid in the main tank 11 is drained. Application of coating liquid is completed.

In the above, the coating liquid overflows from the upper end of the main tank 11 and flows into the sub-tank 12 through the extension wall 17 by making the extension wall 17 nearly vertical without any level difference with the side wall 11a. , no bubbles are generated during inflow. Also, when the coating liquid flows from the outer chamber 20 to the inner chamber 21, air bubbles 23 in the coating liquid are removed by the partition member 22.

Further, in the process of draining the coating liquid in the main tank by the main liquid drain pipe 26, by opening the liquid drain adjustment valve 19 of the auxiliary liquid drain pipe 18 by a predetermined amount, the coating liquid in the main tank 11 is The coating liquid does not stagnate in the corner portion 13 of the present invention, and separation of the coating liquid can be prevented. Since the attachment position of the sub-liquid drain pipe 18 is slightly above the bottom part 11b of the main tank, a small amount of the coating liquid remains at the bottom of the main tank after draining the liquid, and then the coating liquid is supplied from the supply pipe 36. There is no foaming when applying.

The above is only one example of implementing the present invention, and the present invention is not limited to this. For example, a plurality of sub-liquid drain pipes 18 may be arranged above and below, or one of the plurality of corner portions may be arranged. It may be provided only at an arbitrary corner portion. Further, in the illustrated example, the shape of the main tank is substantially quadrilateral in plan view, but it may also be circular or elliptical.

As is clear from the above explanation, according to the present invention, a main liquid drain pipe for discharging the coating liquid in the main tank into the sub-tank is connected to the bottom of the main tank having a corner shape, and Since the auxiliary liquid drain pipe is provided on the side wall of the main tank that forms the corner portion, the coating liquid does not stagnate in the main tank, and the coating liquid does not separate. Therefore, it is possible to apply a homogeneous coating liquid to the surface of the substrate, and the coating film after baking can be made to be excellent without surface defects, and it also has many advantages such as improving product yield. have

[Brief explanation of the drawing]

The drawings show a preferred embodiment of the present invention and a conventional example, and FIG. 1 is a sectional view of a conventional liquid-draining coating device, and FIG. 2 is a sectional view of a liquid-draining coating device according to the present invention. FIG. 3 is a plan view of the liquid drain type coating device according to the present invention, and FIG. 4 is a sectional view showing the attachment part of the sub liquid drain pipe. In addition, 10 in the drawing is a liquid drain type coating device,
11 is a main tank, 12 is a sub tank, 13 is a corner portion, 14 is a coating liquid, 18 is a sub-liquid drain pipe, 26 is a main liquid drain pipe, and 36 is a coating liquid supply pipe.

Claims (1)

[Scope of utility model registration request] In a coating device, a sub-tank is provided below a main tank for coating a substrate, and which receives a coating liquid discharged from the main tank. A liquid drain type coating device characterized in that an auxiliary liquid drain pipe is provided on the side wall of the main tank to which the pipe is connected and which forms the corner portion.