JPH0929719A - Dam structure for coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to supply a solution of the quantity equalized on a coating surface as much as possible by sealing the upstream side of a middle dam, and disposing a regulating plate above the dam, and forming a slit-like overflowing port. SOLUTION: When a film 4 feeding on a receiving base 6 is advanced while being brought into close contact with a backing roll 2, the viscous solution 10 controlled in thickness by a doctor 3 is supplied onto the film 4. The solution 10 is detected in its increase or decrease by a level gage 9, the switching of the valve of a control means is controlled by its output signal, and introduced from a solution supply port 8 into a liquid dam 1. The solution 10 introduced from the port 8 is once deterred before a middle dam 11, fully filled in the sealed space and then overflowed from a space 15. Accordingly, the solution flows forward of the dam 11 in the same thickness. As a result that the solution of the quantity equalized to the coating surface can be supplied, the coating film can be homogenized and the thickness can be made uniform.

Description

Detailed Description of the Invention

[0001]

[Technical field] The present invention provides a medium dam in a liquid dam surrounded by a back wall provided with a solution supply port and both side walls and having a doctor at the tip, and the supplied solution overflows the middle dam. The present invention relates to a coating device adapted to be supplied to the tip side.

[0002]

2. Description of the Related Art In a general coating apparatus, when a viscous solution is supplied into a liquid dam, the flow velocity of the solution is higher than that of other parts on the coating surface located at the shortest distance from the supply port. However, there is a disadvantage that the film thickness formed on the sheet body when passing through the lower surface of the doctor becomes non-uniform. In the known technique disclosed in Japanese Utility Model Publication No. 7-4891, a viscous solution supplied by providing a medium dam in a liquid dam is temporarily pooled on the solution supply side, and the medium dam is overflowed to a solution coating section. The coating speed is made uniform and the coating thickness is made uniform.

However, even if the solution is once pooled on the solution supply side, there is a difference in the flow rate of the solution between the part having the shortest distance between the solution supply port and the middle dam and the other part, and the solution overflows as it is. A liquid dam with a maximum width of 1200 mm is used to form a highly viscous ceramic solution coating (commonly known as a green sheet), but the middle dam has a circular arc-shaped tip and the tip moves 30 mm at the tip moving part. There are differences in degree. The difference in the flow rate of the solution causes a difference in the contact time with the air and causes a slight difference in the viscosity of the solution.
Since the supply amount of the solution to the liquid dam is controlled to be ON-OFF, an arc-shaped striped pattern due to the difference in viscosity appears in the coating film. Therefore, it is the current situation that the problem caused by the difference in coating amount and the difference in flow velocity is not sufficiently solved by simply providing the middle dam.

[0004]

Technical Problem The present invention provides a medium dam in a liquid dam surrounded by a back wall provided with a solution supply port and both side walls and having a doctor at the tip, and the supplied solution overflows the middle dam. It is an object of the present invention to make it possible to supply a uniformized amount of the solution to the coated surface in the coating apparatus that is configured to supply the solution to the tip side.

[0005]

[Technical Means] Technical means for solving this technical problem are: (a) the upstream side of the middle dam is sealed, and (b) the adjusting plate is arranged above the middle dam to provide a slit-like overflow port. Is formed. When the solution supplied to the liquid dam overflows the middle dam, its thickness is adjusted by the adjusting plate. Therefore, in the part of the middle dam that is the shortest distance from the solution supply port, many solutions try to flow out quickly, but the upper part of the middle dam is sealed and the flow is regulated by the adjusting plate in the overflow part as well. The pressure of the solution becomes the internal pressure on the upstream side of the liquid dam and is dispersed. Therefore, there is no great difference in the speed of the solution that overflows the middle dam, and a substantially uniform amount of the solution overflows to the coating side over the entire length of the middle dam. Even when the above-mentioned liquid dam having the maximum width is used, the position of its tip does not exceed 10 mm.

The solution that has overflowed the middle dam stays on the coating side of the liquid dam, but the solution that gradually overflows reaches the bottom of the liquid dam while admixing with the remaining solution, and advances to the doctor. Will collide with. Here, a part forms the coating film on the sheet body, but the other part rises along the doctor and recedes to the middle dam side,
Convection will occur in the solution. The convection generated by the solution, which is almost homogenized in the width direction of the middle dam to the coating side, does not cause a large difference in the flow velocity of the solution in the liquid dam on the coating side, and is almost uniform and stable in the coating part. A quantity of solution can be supplied. Therefore, the supplied solution is smoothly mixed with the staying solution to be convected, and the viscosity thereof is also substantially uniform.

The slit width of the overflow port can be adjusted by moving the height of the adjusting plate (claim 2). The slit width can be accurately adjusted by providing the adjustment portions at appropriate intervals with respect to the adjustment plate. This height adjustment is facilitated by using a push-pull bolt or the like so that the height can be moved by rotating the bolt in the forward and reverse directions.

According to a third aspect of the present invention, in the first and second aspects of the invention, the liquid surface of the coating side of the liquid dam is positioned higher than the overflow port. As described above, the solution overflowing the middle dam causes convection to the solution staying on the coating side of the liquid dam, but the liquid surface on the coating side of the liquid dam is positioned higher than the overflow port. Therefore, the solution overflowing to the coating side directly flows into the retained solution.

[0009]

As a result of being able to supply a uniform amount of solution to the coated surface, the invention of claim 1 has the advantage that the coating film can be homogenized and its thickness can be made uniform, and the film thickness and No crack is generated in the coating film due to the difference in viscosity. Further, in the invention of claim 3, since the solution does not come into contact with air when overflowing, there is an advantage that bubbles are not mixed in the solution and pinholes and irregularities do not occur in the coating film.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a coating apparatus having a liquid dam 1, a backing roll 2 and a pipe doctor 3 as its constituent elements, and shows a schematic side view of the liquid dam 1 with its side wall removed. . When the film 4 traveling on the pedestal 6 moves forward while adhering to the backing roll 2, the viscous solution 10 whose thickness is controlled by the doctor 3 is supplied onto the film 4. The increase / decrease of the solution 10 is detected by the liquid level gauge 9, and the output signal thereof controls the opening and closing of the valve of the control means (not shown) to be introduced into the liquid dam 1 from the solution supply port 8.

Inside the liquid dam 1, a middle dam 11 is provided between the supply port 8 for the solution 10 and the doctor 3, and the tip of the upper lid 5 attached to the rear side of the liquid dam 1 is located above the middle dam 11. Facing, and the solution supply side (rear side) of the liquid dam 1 is on both side walls,
It is hermetically sealed by being surrounded by the rear wall 7 having the supply port 8, the upper lid 5 and the middle dam 11. An adjusting plate 12 is attached to the lower surface of the tip portion of the upper lid 5, and forms a slit-shaped space 15, that is, a discharge port of the solution 10, with the upper surface of the middle dam 11. A plurality of push-pull bolts 13 (only one is shown in the drawing) are attached to the adjusting plate 12 in the width direction, and by rotating the bolts 13, the distance from the intermediate dam 11, that is, the thickness of the slit. Can be adjusted.

Since the solution 10 introduced from the supply port 8 is once retained in front of the middle dam 11 and fills the sealed space and then overflows from the space 15, the solution has the same thickness and is in front of the middle dam 11. Will flow to.
In this embodiment, the liquid level in front of the middle dam 11 is the space 15
Since the solution 10 is set at a higher position and overflows, the solution 10 directly enters into the staying solution from below the liquid surface.

Since this coating apparatus 1 uses the slit-shaped space 15, the retention width of the solution can be adjusted according to the width of the coating film. That is, the space of the slit-shaped space 15 can be adjusted by the bolt 13, but if the spacer 21 is sandwiched between the space formed by the upper surface of the middle dam 11 and the adjustment plate 12, the overflow width of the solution 10 can be changed. Yes (see Figure 2). This spacer 21
Is designed to correspond to the desired coating width. By attaching the side wall plate 22 according to the installation position of the spacer 21, the dam width on the coating side can be matched with the coating width. In FIG. 2, the side wall plate 22 is shown as being fixed to the upper lid 5 with thumbscrews 23. Side wall plate 22
In the case of fixing to the upper lid 5, female screws may be formed on the upper surface of the upper lid 5 in accordance with the coating width.

[Brief description of drawings]

FIG. 1 is a schematic side view of a coating apparatus with a side wall removed.

FIG. 2 is a schematic side view of a coating apparatus according to another embodiment.

[Explanation of symbols]

2 backing rollers, 3 pipe doctors, 4
Sheet body, 8 solution supply port, 10 solution, 11
Medium dam, 12 adjustment plates, 13 push-pull bolts,
15 Slit space

Claims (3)

[Claims] 1. A medium dam is provided in a liquid dam surrounded by a back wall provided with a solution supply port and both side walls and a doctor is arranged at the tip, and the supplied solution overflows the medium dam and the tip side. In the coating apparatus, the upstream side of the middle dam is sealed and an adjusting plate is arranged above the middle dam to form a slit-shaped overflow port. 2. The coating apparatus according to claim 1, wherein the adjusting plate is attached so as to be vertically movable. 3. The coating apparatus according to claim 1, wherein the liquid surface on the tip side of the liquid dam is higher than the overflow port.