JPH05337411A - Coating material applying method and applying device with bar - Google Patents

Abstract

PURPOSE:To provide the applying method and applying device which widen a range for flattening the film thickness of a coated substrate and can suppress an increase in the film thickness at the rear end of the substrate in the case of applying a color filter material to be used for a liquid crystal television, etc., to the non-continuous substrate, such as glass substrate, by using a bar. CONSTITUTION:The coating liquid in a coating liquid pan is moved to an auxiliary tank 19 by a pressure regulator 21 and the liquid level of the coating liquid is temporarily lowered with respect to the bar at the time of coating the rear end of the substrate. Consequently, a liquid pool 18 behind the bar flows down simultaneously. The coating liquid sticking to the rear end of the substrate is decreased by the decrease in the amt. of the liquid pool, by which the film thickness distribution at the rear end of the substrate is improved. Since the range of the uniform film thickness is wide, the image uniform over the entire part of the screen of the liquid crystal television is obtd. if the method is used for coating the substrate with the color filter material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to adjusting the coating amount applied to a discontinuous substrate using a bar. Specifically, the present invention relates to a bar coating method and an apparatus which are optimal as a coating method of a color filter material used in a liquid crystal color television or the like.

[0002]

2. Description of the Related Art The bar coating method is a general method for uniformly coating a flexible continuous film (web). Figure 3
FIG. 3 is a schematic view of a conventional bar coating device applied to a discontinuous substrate. A glass substrate is used here as the discontinuous substrate. In FIG. 3A, the bar 1 is partially immersed in the coating solution pan 3 in which the coating solution 2 is stored and is rotated. The bar is formed by tightly winding a thin metal wire 5 around the outer circumference of the metal round bar 4 as shown in FIG. 3b. As the bar 1 rotates, the coating solution 2 in the coating solution pan is picked up and applied to the running glass substrate 6 to form a coating film 7. On this occasion,
The coating liquid is measured at the contact portion between the substrate and the bar, and only the desired coating amount is coated on the glass substrate 7. Others form a liquid pool 8 with the newly supplied coating liquid,
In the steady state, the coating liquid is applied to the substrate through the liquid pool.

[0003]

However, at the end of coating, the liquid pool tends to adhere to the final end of the substrate 6 due to the viscosity of the coating liquid, resulting in a thick coating film.

As the coating film 7 becomes thicker, the ratio of the flat portion of the film thickness decreases, and the utilization factor of the substrate deteriorates. Further, when the coating film is patterned by photolithography, it is difficult to remove the portion having a large film thickness by development, and the remaining film is often left.

To improve this, it is possible to stop the rotation of the bar when the final end of the substrate approaches approximately 10 to 20 mm, eliminate the pick-up of new coating liquid, and coat the final portion of the substrate with the liquid pool. It is considered. However, even in this case, the thick coating of the coating film is not improved so much.

An object of the present invention is to solve the above problems of the conventional bar coating method and improve the coating film thickness uniformity of a discontinuous substrate.

[0007]

In order to achieve the above object, the technical means of the present invention is to apply the liquid level of a coating pan in which the bar is dipped to the bar when the final end of the discontinuous substrate is coated. It is to lower temporarily.

[0008]

According to the above-mentioned structure, when the liquid level of the coating liquid drops, the viscosity causes the liquid pool to drop downward, the liquid pool at the contact portion between the substrate and the bar decreases, and the coating that adheres to the final end of the substrate is applied. As the amount of liquid decreases, the increase in film thickness at the edge of the substrate becomes slight,
The film thickness uniformity is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the schematic view of the bar coating apparatus of FIG. In FIGS. 1A and 1B, the bar 11 is partially immersed in the coating solution pan 13 in which the coating solution 12 is stored and is rotated. The coating liquid pan communicates with the auxiliary tank 19 through the pipe 20, and the coating liquid 12 can move between the coating liquid pan 13 and the auxiliary tank 19. A pressure adjusting device 21 is connected to the auxiliary tank 19, and the pressure of the auxiliary chamber 23 can be adjusted by moving the piston wall 22 in the auxiliary tank to the left and right. Although not shown, a coating liquid supply device is separately provided so as to detect the liquid surface height of the coating liquid pan before starting the substrate coating and maintain the liquid surface height at a predetermined value.

As the bar 11 rotates, the coating solution 12 in the coating solution pan 13 is picked up and applied to the glass substrate 16 running in the direction B to form a coating film 17. The coating liquid is measured at the contact portion between the glass substrate 16 and the bar 11, and a liquid pool 18 is formed by the remaining coating liquid and the newly picked-up coating liquid.

At about 20 mm from the rear end of the substrate, the bar 11
Stops, the pressure adjusting device 21 further operates, the piston wall 22 in the auxiliary tank 19 moves to the left, and the pressure in the auxiliary chamber 23 becomes a negative pressure. Coating solution in coating solution pan 12
Is exposed to the atmosphere, the coating liquid in the coating liquid pan flows into the auxiliary tank. Therefore, the liquid surface of the portion of the coating liquid pan in which the bar is immersed suddenly drops. At this time, the resist in the liquid pool also flows down along with the decrease in the liquid surface due to the viscosity of the resist, and the amount of resist applied to the final end is reduced, and the increase in film thickness is suppressed.

FIG. 2 shows the film thickness distribution of the coating film at the rear end of the substrate when the coating method of the present invention is used. Compared with the conventional coating method, the increase in the film thickness at the rear end portion is suppressed to be low, and the range of the flat film thickness portion is widened.

Here, the faster the liquid level of the coating pan is lowered, the more easily the resist in the liquid pool portion flows down.
The smaller the flow resistance of the path from the coating liquid pan 13 to the pipe 20, the greater the effect.

However, when the liquid level of the coating pan is lowered,
It is necessary to stop the function of the coating liquid supply device and not supply new resist.

When the substrate coating is completed, the bar is rotated again, the resist in the auxiliary tank is moved to the coating liquid pan, and the coating liquid supply device is also operated to adjust the liquid level until the next substrate is coated. Keep at a specified value.

[0016]

As is apparent from the above description, according to the present invention, it is possible to obtain a coated substrate having excellent film thickness flatness without increasing the film thickness at the final end of the substrate. Therefore, a wider range of non-continuous substrates can be used as an effective surface. as a result,
By using the method of the present invention for forming pixels such as color filters of a color liquid television, it is possible to obtain a uniform image on the entire screen.

[Brief description of drawings]

FIG. 1A is a process diagram of a bar coating method carried out by using the present invention. FIG. 1B is a process diagram of the bar coating method in different states.

FIG. 2 is a diagram showing the film thickness distribution at the rear end of the substrate when the bar coating method of the present invention is used and when the conventional bar coating method is used.

FIG. 3A is a process diagram showing a conventional bar coating method. FIG. 3B is a sectional view of both ends of the bar cut away.

[Explanation of symbols]

 11 bar 12 coating liquid 13 coating liquid pan 16 glass substrate 19 auxiliary tank

Claims (2)

[Claims] 1. A method of coating a discontinuous substrate with a bar partially immersed in a coating solution, wherein at the end of coating, the liquid surface of the coating solution in the portion where the bar is immersed is changed to a bar. The bar coating method is characterized by temporarily lowering. 2. An apparatus for coating a discontinuous substrate with a bar partially immersed in a coating liquid in a coating liquid pan, wherein an auxiliary tank and a coating liquid are provided between the coating liquid pan and the auxiliary tank. A bar coating device comprising means for alternately flowing between the two and a pressure adjusting device for adjusting the pressure of the auxiliary tank.