JP2000126660A - Coating apparatus for belt-shaped material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus in which the effect of preventing irregularity of coating due to bubbles being caught in is large. SOLUTION: In a coating device in which a part of a pickup roll 3 is soaked in coating liquid 2 in a coating pan 1 and the coating liquid drawn while the pickup roll 3 is rotated is applied to a belt-shaped material S, the coating pan 1 is provided with a coating liquid feeding header 7 to the coating pan 1 extending in the axial direction of the pickup roll 3 on one side thereof, and is provided with an overflow part 8 of the coating liquid 3 on the other side of the coating pan 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for applying a coating liquid, which is drawn by rotating a pickup roll, to a belt-shaped material.

[0002]

2. Description of the Related Art A coating apparatus for immersing a part of a pickup roll in a coating liquid of a paint pan and applying a coating liquid pumped up while rotating the pickup roll to a strip material directly or through another roll is known. Widely used.

In the above-mentioned coating apparatus, a coating liquid tank for storing the coating liquid is separately provided, and the coating liquid is circulated between the coating pan and the coating liquid tank. For example, as shown in FIG. 4, a coating liquid is supplied from a coating liquid tank (not shown) to the coating pan 1 via a coating supply pipe 21, and the coating liquid overflows from a drain port 22 to the coating liquid tank. return. When air bubbles generated during the circulation of the coating liquid are caught in the coating liquid pumped up by the pickup roll 3, application unevenness due to the inclusion of the air bubbles on the application surface of the band-shaped material S occurs.

In Japanese Utility Model Laid-Open No. 5-70671, as shown in FIG. 5, a supply hose 21 for supplying a coating liquid to the paint pan 1 extends horizontally from a header portion, and a drain port 22 extends from the middle of the hose. Using a roll coater type coating apparatus having a plurality of nozzles 23 that bend in the direction and having a nozzle header 24 set in parallel with the pickup roll 3 on the paint pan 1, the height of the tip of the nozzle 23 is adjusted to the liquid level to foam. In addition, the coating liquid supplied to the coating pan 1 is
Describes that the foamed bubbles are broken by making the flow rectified in the discharge direction.

[0005]

SUMMARY OF THE INVENTION
In the coating apparatus described in Japanese Patent Application Laid-Open No. 0671, a part of bubbles generated during the circulation of the coating liquid moves to the pickup roll 3 side and is caught by the pickup roll 3. In addition, bubbles generated by the rotation of the pickup roll 3 stay on the liquid surface of the paint pan 1 on the side opposite to the nozzle header 24 of the pickup roll 3, and the bubbles are caught in the pickup roll 3. Therefore, the effect of preventing coating unevenness due to entrapment of air bubbles is insufficient.

The present invention has been made in consideration of the above problems, and has as its object to provide a coating apparatus having a large effect of preventing coating unevenness due to entrainment of air bubbles.

[0007]

Means for Solving the Problems In order to prevent coating unevenness caused by entrainment of air bubbles, the present inventors have made it necessary to prevent air bubbles from reaching the pickup roll in addition to preventing air bubbles from staying in the paint pan. It has been found that it is effective to prevent adhesion to the pickup roll. The present invention is based on this finding, and the means of the present invention for solving the above problems are as follows.

(1) In a coating apparatus in which a part of a pickup roll is immersed in a coating liquid of a paint pan and a coating liquid pumped up while rotating the pickup roll is applied to a strip material, a pickup is picked up on one side of the paint pan. An apparatus for applying a strip material, comprising: a coating liquid supply header for a coating pan extending in a roll axis direction; and a coating liquid overflow section on the other side of the coating pan.

(2) In the above (1), the coating liquid supply header is disposed so that the coating liquid supplied from the coating liquid supply header collides with the pickup roll below the liquid level. apparatus.

(3) The apparatus for coating a strip material according to (1) or (2), wherein the coating liquid supply header is provided with means for equalizing the discharge amount of the coating liquid in the header longitudinal direction.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main part of a coating apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a paint pan, 2 is a coating liquid, 3 is a pick-up roll, 4 is an applicator roll, 5 is a backup roll for supporting the strip S, 6 is a coating liquid supply pipe, 7 is a coating liquid supply header,
Reference numeral 8 denotes an overflow pipe for the coating liquid provided at two locations on both sides of the coating pan 1 in the roll axis direction, 9 denotes a coating liquid tank, and 10 denotes a pump.

In the apparatus shown in FIG. 1, a coating liquid 2 in a coating liquid tank 9 is supplied to a coating pan 1 from a coating liquid supply header 7 through a coating liquid supply pipe 6 via a pump 10. Paint pan 1
Is supplied toward the lower portion of the pick-up roll 3, flows below the pick-up roll 3, flows to the opposite side of the pick-up roll 3, and overflows the coating liquid 2 provided on the opposite side. After overflowing from 8, it returns to the coating liquid tank 9.

FIG. 2 is a diagram showing a main part of the coating liquid supply header 7 of FIG. 2A is a perspective view of the coating liquid supply header in the longitudinal direction, and FIG. 2B is a detailed perspective view of the coating liquid supply header 7. The coating liquid supply header 7 includes a rectifying plate 11
Is divided into header chambers 12a and 12b by
The two header chambers communicate with each other through a plurality of openings 13 provided in the current plate 11. Also, a coating liquid supply pipe 6a connected to both ends of the header chamber 12a of the coating liquid supply header 7,
6b, the coating liquid can be supplied from the coating liquid supply header 7 to the pickup roll 3 facing portion side of the header chamber 12b.
Many slit-shaped discharge ports 1 flat in the longitudinal direction of the header
4 is provided so that the discharged liquid can collide with the pickup roll 3 below the liquid level.

In the coating liquid supply header 7, since the coating liquid is supplied from both ends of the header 7 and includes the rectifying plate 11,
In the header chamber 12b, the hydraulic pressure in the header longitudinal direction becomes uniform. Therefore, the coating liquid discharged from the header chamber 12b becomes uniform in the header longitudinal direction, and a rectified flow toward the pickup roll 3 is formed. Discharge port 14
May be circular, but in the apparatus of FIG. 1, since the discharge ports are slit-shaped flat in the longitudinal direction of the header, the effect of rectification is more excellent.

The coating liquid 2 supplied to the coating pan 1 contains air bubbles. Some of these bubbles float on the paint pan 1 and break, but some remain on the liquid surface without breaking. In the conventional coating apparatus, when the pickup roll 3 rotates, air bubbles remaining on the liquid surface adhere to the pickup roll 3 together with the coating liquid 2 and are pumped up.
Coating unevenness.

FIG. 3 is a view showing a discharge direction of the coating liquid discharged from the coating liquid supply header 7 toward the pickup roll 3 in the apparatus shown in FIG. The coating liquid discharged from the coating liquid supply header 7 collides with the pickup roll 3 below the liquid level.

In the apparatus shown in FIG. 1, as shown in FIG. 3, the coating liquid 2 collides with the lower portion of the pickup roll 3 below the liquid level, and blows off the bubbles trapped in the pickup roll 3. After the collision, a part of the coating liquid flows upward, and this flow breaks bubbles on the liquid surface. Since a rectified flow is formed in the longitudinal direction of the pickup roll 3,
The above effect can be exerted in the entire width of the pickup roll 3 in the longitudinal direction, and it is possible to reliably prevent air bubbles from getting into the pickup roll 3.

If the direction of discharge of the coating liquid is too downward and the coating liquid does not collide with the pickup roll 3,
If the effect of blowing off the air bubbles entrained in the pickup roll 3 is reduced, and if it becomes too upward and does not collide with the pickup roll 3 below the liquid level, the effect of blowing out the air bubbles entrained in the pickup roll 3 is reduced. Not only that, the liquid surface is agitated after the collision with the pickup roll 3 on the liquid surface or directly, and conversely, the entrapment of bubbles increases. In order to enhance the effect of preventing bubbles from being trapped in the pickup roll 3, it is preferable that the coating liquid supplied from the coating liquid supply header collides with the pickup roll below the liquid level, as shown in FIG.

The coating solution 2 flows under the pickup roll 3 and flows to the opposite side of the pickup roll 3. In the area on the opposite side of the pick-up roll 3, bubbles are generated when the pick-up liquid 3 is rotated or the coating liquid 2 scraped off between the pick-up roll 3 and the applicator roll 4 returns to the paint pan 1. If these air bubbles stay in the paint pan 1, they are caught in the pickup roll and cause uneven coating.

In the apparatus shown in FIG. 1, the coating liquid 2 that has passed under the pickup roll 3 is uniformly distributed toward an overflow pipe 8 provided in the coating pan 1 opposite to the coating liquid supply header 7. Flow, discharged from the overflow pipe 8,
Air bubbles do not stay in the paint pan 1. Therefore, it is possible to prevent coating unevenness caused by the pickup roll 3 entraining the air bubbles staying in this area.

As described above, in the apparatus shown in FIG. 1, the retention of bubbles in the paint pan 1 can be reduced, and the retained bubbles can be prevented from adhering to the pickup roll 3 and being rolled up. The effect of preventing coating unevenness caused by this is excellent.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the coating apparatus shown in FIG.
Using silica having a different shape and a different coating liquid discharge direction (θ in FIG. 3), silica is contained, and the solid content concentration is 6%.
When the chromate treatment aqueous solution was applied to a steel sheet at a wet adhesion amount of about 1 g / m ² (50 mg / m ^{2 in} terms of chromium), the occurrence of uneven coating due to entrapment of air bubbles was investigated. The size of the slit-shaped opening is 1 mm × 25 mm at the center, and the length in the header longitudinal direction is increased toward the end, and is 1 mm × 28 mm at the end. When the discharge direction (θ) is 10 °, the coating liquid collides with the pickup roll below the liquid surface, and when the discharge direction (θ) is 15 °, the coating liquid does not collide with the pickup roll below the liquid surface.

The degree of uneven coating was evaluated by visually observing the appearance of the steel sheet after coating, and according to the following criteria according to the degree of uneven coating (linear unevenness). ◎: No linear unevenness was observed. ○: Almost no linear unevenness was generated. Δ: Slight linear unevenness was generated. X: Clear linear unevenness was generated.

For comparison, a similar investigation was carried out using the coating apparatus shown in FIG. Table 1 shows the results of these investigations.

[0025]

[Table 1] The example of the present invention is excellent in the effect of preventing the entrapment of air bubbles by the pickup roll, so that the occurrence of coating unevenness is smaller than that of the comparative example.

In the examples of the present invention, when the coating liquid collides with the pickup roll below the liquid surface or when the shape of the discharge port is a slit, the effect of preventing coating unevenness is more excellent.

Although the present embodiment is an example of a coating apparatus having two coating rolls, the same effect can be obtained in a coating apparatus having a number of coating rolls other than two.

[0028]

According to the coating apparatus of the present invention, the entrapment of air bubbles by the pickup roll can be prevented, so that the occurrence of uneven coating due to the entrainment of air bubbles can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a coating apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of a coating liquid supply header used in the coating apparatus of FIG.

FIG. 3 is a view showing a discharge direction of a coating liquid in the coating apparatus of FIG. 1;

FIG. 4 is a view showing a conventional coating apparatus.

FIG. 5 is a view showing a coating apparatus described in Japanese Utility Model Laid-Open No. 5-70671.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paint pan 2 coating liquid 3 pickup roll 4 applicator roll 5 backup roll 6 coating liquid supply pipe 7 coating liquid supply header 8 overflow pipe (overflow section) 9 coating liquid tank 10 pump 14 discharge port S belt-shaped material

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Chitoshi Nojima 1-2-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4F040 AA22 AC01 BA23 CB22 CB40 DA12 DA20 DB22 DB25 4F042 AA22 BA12 BA13 CA06 CB04 CB11 CB20

Claims (3)

[Claims] 1. A coating apparatus in which a part of a pickup roll is immersed in a coating liquid of a paint pan, and the coating liquid pumped up while rotating the pickup roll is applied to a strip material. An apparatus for applying a strip material, comprising: a coating liquid supply header for a coating pan extending in a roll axis direction; and a coating liquid overflow section on the other side of the coating pan. 2. The apparatus according to claim 1, wherein the coating liquid supply header is disposed such that the coating liquid supplied from the coating liquid supply header collides with a pickup roll below the liquid level. . 3. The belt-shaped material coating apparatus according to claim 1, wherein the coating liquid supply header includes a unit for equalizing a discharge amount of the coating liquid in the header longitudinal direction.