JP2013237000A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus capable of preventing a surface defect due to the scattering of a coating liquid near a joint part (welded part) of a belt-like body.SOLUTION: A coating apparatus for moving a coating liquid 4 pulled up from a coater pan 6 by a pickup roller 3 into an applicator roll 2 and transferring from the applicator roller to the surface of a belt-like body 1 is configured so that an edge wiper 11 is abutted to a roller surface locating in both end part side in the body length direction of the applicator roller and in an upper position than a contact part of the applicator roller with the pickup roller, and further, a scattered coating liquid collecting plate 14 is provided across the edge of two coater pans for the front and back surface of the belt-like body below both side end parts in the body length direction of the applicator roller.

Description

  The present invention relates to a coating apparatus that includes at least an applicator roll and a pickup roll and applies a coating liquid to the surface of a strip-like body such as a steel plate (steel strip) that is continuously conveyed substantially vertically upward.

  For example, surface-treated steel sheets such as galvanized steel sheets that have been hot-dip galvanized on the surface of cold-rolled steel sheets, and alloyed hot-dip galvanized steel sheets that have undergone alloying treatment are used to improve the corrosion resistance. It is generally performed to form a chromate film containing Cr. In recent years, attention has been paid to organic films and inorganic films that do not contain Cr, so-called chromium-free films, instead of chromate films because of concern about the effect of Cr on the human body. As a method of depositing the chromate film or the chromium-free film containing no Cr on the steel sheet surface, a coating apparatus in which two or three or more coating rolls are disposed on the steel sheet surface that is continuously passed through. It is common to use this method.

  FIG. 1 is a longitudinal sectional view showing a configuration example of a coating apparatus for applying a coating liquid for forming a film on the surface of a belt-like body conveyed in a substantially vertical upward direction (see Patent Document 1). In FIG. 1, 1 is a belt-like body, 2 is an applicator roll, 3 is a pickup roll, 4 is a coating solution, 5 is a coating solution film, and 6 is a coater pan that stores the coating solution 4. Moreover, the arrow in a figure shows the conveyance direction of the strip | belt-shaped body 1 about a strip | belt-shaped body, and the rotation direction of each roll about the applicator roll 2 and the pick-up roll 3. FIG.

  In the apparatus of FIG. 1, applicator rolls 2 are disposed on both sides of the belt-like body 1 conveyed in a substantially vertical upward direction so as to contact the surface of the belt-like body 1. A pickup roll 3 is disposed so as to abut. A part of the pick-up roll 3 is immersed in the coating liquid 4 stored in the coater pan 6, and when the pick-up roll 3 rotates in the direction of the arrow, the coating liquid 4 adhered to the surface of the pick-up roll 3 is coated. Pulled up from pan 6. The coating liquid pulled up by the pickup roll 3 is then moved to the surface of the applicator roll 2 that comes into contact with the pickup roll 3 and is further transferred to the surface of the strip 1 that comes into contact with the applicator roll 2. The coating liquid film 5 is continuously formed on both sides of 1. Thereafter, the coating film is dried and baked in a drying / baking facility (not shown) to form a predetermined film.

  When the coating liquid is applied to the band 1 using a coating apparatus as shown in FIG. 1, the film thickness of the coating liquid in the vicinity of both end portions in the trunk length direction that does not come into contact with the band of the applicator roll 2 due to the surface tension of the coating liquid. It becomes thicker, and the coating liquid scatters from this part and falls downward. The dropped coating liquid adheres to the surface of the belt 1 or adheres to the surface of the transport roll disposed below the coating apparatus, and then is transferred to the belt 1 to cause a surface defect such as poor appearance. cause.

  Moreover, the viscosity of a coating liquid is falling by switching from the chromate film | membrane mentioned above to a chromium free film | membrane, and there exists a tendency for scattering of a coating liquid to increase. Furthermore, in recent years, from the viewpoint of improving productivity, there is a tendency to increase the coating speed (conveying speed of the belt-like body), and the rotational speed of the applicator roll increases accordingly, coupled with a decrease in the viscosity of the coating liquid. The above-mentioned scattering problem has become more obvious and is one of the factors that hinder the improvement of productivity.

  As a technique for solving the above problems, Patent Document 2 discloses an applicator roll end portion above a contact portion between an applicator roll and a pickup roll in a coating apparatus for a strip (steel strip) including an applicator roll and a pickup roll. A method has been proposed in which an edge wiper is brought into contact with the peripheral surface in the vicinity, thereby scraping off excess coating liquid in the vicinity of the end of the applicator roll and returning the scraped coating liquid to the coater pan.

JP 2007-31482 A JP 2009-202041 A

  By applying the technique of Patent Document 2, surface defects due to the scattering of the coating liquid on the surface of the belt-like body can be greatly reduced. However, in the coating device, since the strip is continuously conveyed, in the vicinity of the portion where the preceding strip and the subsequent strip are connected by welding or the like, surface defects caused by the scattering of the coating liquid are still present. Has occurred, and the appearance defect has not been completely eliminated.

  The present invention has been made in view of the above-described problems of the prior art, and the object thereof is to prevent surface defects caused by the scattering of coating liquid in the vicinity of the connecting portion (welded portion) of the belt-like body. An object of the present invention is to provide a coating apparatus that can perform such a process.

  The inventors have intensively studied to solve the above problems, and have developed the following present invention. That is, the present invention provides a coating apparatus for transferring a coating liquid pulled up from a coater pan by a pick-up roll to an applicator roll, and further transferring the coating liquid from the applicator roll to the surface of the belt-like body. The edge wiper is in contact with the roll surface on the side and above the contact portion between the applicator roll and the pick-up roll, and further, two coater pans for the front and back surfaces of the belt-like body below the both ends of the applicator roll in the body length direction. It is a coating apparatus characterized by providing a scattering coating liquid capture board across the edge of this.

  In the coating apparatus of the present invention, the scattered coating liquid catching plate is formed such that a central portion in the direction connecting the two coater pans is high, and both end portions perpendicular to the direction are formed higher than the central portion. And

  Further, the scattering coating liquid capturing plate in the coating apparatus of the present invention can be expanded and contracted in accordance with a change in the interval between the two coater pans.

  Further, the scattering coating liquid catching plate in the coating apparatus of the present invention is composed of two catching plates individually installed on the edges of the two coater pans, and they form an overlapping portion between the two coater pans. In addition, the length of the overlapping portion changes according to the interval between the two coater pans.

  According to the present invention, it is possible to completely eliminate surface defects (appearance defects) caused by scattering of the coating liquid that occurs when the band-shaped joint passes through the coating apparatus. A coated product with excellent quality can be obtained.

It is a longitudinal cross-sectional view which shows one structural example of the conventional coating apparatus. It is a longitudinal cross-sectional view of the coating apparatus disclosed in Patent Document 2. It is a perspective view of the coating apparatus disclosed by patent document 2. FIG. It is a longitudinal cross-sectional view of the coating apparatus of this invention which installed the scattering coating liquid capture | acquisition board in the coating apparatus of FIG. It is an example figure which shows the scattering coating liquid capture | acquisition board suitable for this invention. It is another example figure explaining the scattering coating liquid capture | acquisition board suitable for this invention. It is a perspective view explaining the example which installed edge blow in the coating device of FIG. It is a figure explaining the coating apparatus which provided the scattering coating liquid capture | acquisition board of FIG. 6 in the coating apparatus of FIG. 3 used for the Example. It is a perspective view of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a vertical cross-sectional view of the portion of the coating apparatus disclosed in Patent Document 1 where the edge wiper 11 is installed, as viewed from one width end of the band 1 to the other width end. . The apparatus of FIG. 2 is provided with an edge wiper 11 compared to the apparatus of FIG. FIG. 3 is a perspective view of the coating apparatus of FIG. 2 and shows only the coating apparatus on one side of the belt 1.

  As shown in FIG. 3, the edge wiper 11 is a roll in the vicinity of the ends on both sides in the longitudinal direction of the applicator roll 2 that does not come into contact with the belt-like body and above the contact portion between the applicator roll 2 and the pickup roll 3. The coating liquid 12 is disposed so as to contact the surface, scrapes off the coating liquid locally adhered to the roll surface in the vicinity of both ends of the applicator roll 2 in the body length direction, and coats the coating liquid 12 thus scraped off into the coater. It plays the role of returning to the inside of the pan 6.

  By using such a coating apparatus, it is possible to scrape with the edge wiper 11 the coating liquid that has adhered excessively in the vicinity of both end portions of the applicator roll 2 in the body length direction. It is possible to prevent the coating liquid from splashing on the surface, and consequently, it is possible to effectively prevent appearance defects caused by the coating liquid scattering.

  However, when trying to apply and form a coating film such as a rust-preventive film on a strip such as a galvanized steel sheet using the above-mentioned coating apparatus, the surface in the longitudinal center of the strip is caused by the scattering of the coating liquid. Although the defects could be almost eliminated, it was found that the surface defects due to the scattering of the coating liquid still occur at the front end portion in the longitudinal direction although the degree of occurrence is reduced.

  The inventors investigated the cause of the above-mentioned defect occurrence, and found that the surface of the roll was damaged when the connecting portion connecting the preceding strip and the following strip by welding or the like passed through the coating apparatus. In order to prevent this, the operation of temporarily opening the applicator roll 2 disposed opposite to both sides of the belt-like body is performed, and the applicator roll 2 is caused by the vibration accompanying the movement of the applicator roll 2. The coating liquid staying at both ends of the body length direction of the steel is scattered, or passes through the gap between the two coater pans for the front and back surfaces of the belt and adheres directly to the surface of the belt, or the scattered liquid is transported After adhering to the roll, it is clearly transferred to the surface of the band-like body, which causes an appearance defect in the range of about 10 m (longitudinal front end portion) after the joining portion of the band-like body. It became.

  Therefore, the inventors further attempted to reduce the opening / closing speed of the applicator roll in order to prevent the appearance failure due to the scattering of the coating liquid at the tip portion after the joining portion of the strip. However, it has been found that slowing the opening and closing speed of the applicator roll 2 only increases the number of non-painted portions, and is not very effective in suppressing coating film scattering. Thus, the present invention has been completed by repeatedly investigating a method for preventing the scattered coating liquid from adhering to the surface of the band even though the coating liquid is allowed to be scattered.

  That is, the coating apparatus according to the present invention is a roll disclosed in the above-mentioned Patent Document 1 in the vicinity of the end portion where the belt-like bodies on both sides of the applicator roll in the trunk length direction do not contact and the portion above the contact portion between the applicator roll and the pickup roll. As shown in FIG. 4, two coater pans 6 for the front and back surfaces of the belt-like body are provided below the both ends of the applicator roll 2 in the body length direction with respect to the coating apparatus having the edge wiper in contact with the surface. The scattering coating liquid catching plate 14 is provided so as to straddle the edges of the above. By providing the scattered coating liquid catching plate 14, it is possible to prevent the coating liquid scattered by the vibration at the time of opening and closing the applicator roll 2 from passing through the coater pan 6 and adhering to the belt-shaped body and the transport roll.

  However, in the case where the scattered coating liquid catching plate 14 is a simple flat plate, when a large amount of coating liquid is scattered, the captured coating liquid drops from the end of the scattered coating liquid catching plate to the strip or the transport roll. Cause secondary appearance defects. Therefore, as shown in FIG. 5, the scattering coating liquid capturing plate 14 has a central portion in the direction (length direction) connecting the two coater pans 6 and a direction perpendicular to the direction (width direction). ) Are preferably higher than the central portion. By adopting such a shape, the captured coating liquid moves to the center side in the width direction of the scattered coating liquid capturing plate, and further flows in either direction of the two coater pans 6. It can be recovered in the coater pan 6 without dripping from the part.

  Moreover, the space | interval between the two coater pans 6 changes with the joining part of a strip | belt-shaped body passing, and coating conditions. Therefore, the splash coating liquid capture plate 14 of the present invention has a degree of freedom in the angle of the top of the capture plate, for example, as shown in FIG. 5, according to the change in the interval between the two coater pans. It can be expanded and contracted according to the change in the interval, or has a degree of freedom so that it can move without fixing the engaging part (attachment part) to the edge of the coater pan 6 provided at the lower part of the catch plate It is preferable that

  Further, as shown in FIG. 6, the splashing coating liquid catching plate 14 is composed of two catching plates 14a and 14b, each being fixed to the edge of two coater pans, Install the capture plate so that there is no gap between the two capture plates even if the capture plate overlaps between the two coater pans and the length of the overlap varies depending on the distance between the two coater pans. May be.

  The length of the scattering coating liquid capturing plate 14 may be longer than the maximum distance between the two coater pans, but is preferably separated from the pickup roll by 100 mm or more so as not to contact the pickup roll. Moreover, it is preferable that the width | variety of the scattering coating liquid capture | acquisition board 14 shall be 100-300 mm.

Next, the coating apparatus shown in FIGS. 2 to 4 suitable for installing the scattered coating liquid catching plate 14 of the present invention will be specifically described.
First, the portion where the coating liquid is excessively adhered locally to the roll surface of the applicator roll 2 is a position that is about 10 mm inward from both ends of the roll body length where the belt-shaped body is not in contact. Preferably, the applicator roll 2 is provided in the vicinity of both end portions in the body length direction. However, if the length in the body length direction of the contact portion between the edge wiper 11 and the applicator roll 2 is large, the amount of coating liquid scraped off by the edge wiper 11 increases, and the scraped coating liquid returns to the coater pan 6. There is a risk of causing liquid splash and adhering to the belt-like body 1 being conveyed. Therefore, it is preferable that the contact portion between the edge wiper 11 and the applicator roll 2 is in a range of 50 to 100 mm from both end portions in the body length direction of the applicator roll 2.

  Moreover, it is preferable to project the edge part of the edge wiper 11 about 10-20 mm from the edge part of the applicator roll 2 to a trunk | drum length direction. The reason for this is that the scraped coating liquid may wrap around the roll surface of the applicator roll 2 again through the applicator roll 2 barrel end and thicken and the coating liquid may scatter.

  Moreover, it is preferable that the angle θ (see FIG. 2) between the position where the applicator roll 2 contacts the edge wiper 11 and the line connecting the axes of the applicator roll 2 and the horizontal plane is within a range of 30 to 45 °. The reason for this is that when θ exceeds 45 °, the landing point of the coating liquid returning into the coater pan 6 is too close to the strip 1 and the coating liquid 12 scraped off by the edge wiper 11 adheres to the strip 1. Or when returning to the edge coater pan 6, the generated liquid splash may adhere to the band 1. On the other hand, if θ is less than 30 ° and the edge wiper 11 is too close to the pickup roll 3, the amount of coating liquid transferred from the pickup roll 3 to the applicator roll 2 may be uneven due to the scraped coating liquid. Because.

  The edge wiper 11 is preferably made of a material that does not damage the surface of the applicator roll 2, has an appropriate scraping force, and does not penetrate the coating liquid. From the viewpoint, an elastic resin sponge is preferable. In addition, the shape of the edge wiper 11 is not particularly limited, but it is preferable that the edge wiper 11 is formed in a substantially rectangular parallelepiped shape and is arranged so that the corner (ridge portion) abuts the applicator roll 2.

  2, when the coating liquid 12 scraped by the edge wiper 11 returns to the edge coater pan 6, liquid splash occurs and adheres to the belt 1 or the transport roll. May cause defects. Therefore, as shown in FIG. 7 between the contact portion of the edge wiper 11 and the applicator roll 2 and the contact portion of the applicator roll 2 and the pickup roll 3 of the coating apparatus shown in FIG. An edge blowing device 15 may be installed in the vicinity of the roll surface, and gas may be sprayed from the inner side to the outer side in the body length direction of the applicator roll to blow off the scraped coating liquid 12.

In addition, the kind of gas to spray is not specifically limited. However, if the gas spray pressure is too low, the above effect is not exhibited. On the other hand, if the gas spray pressure is too high, the coating liquid 12 scraped off by the edge wiper 11 will jump out of the coater pan 6. It is desirable to adopt an appropriate pressure in consideration. As an example, when air is used as the gas to be blown, the blowing pressure may be about 2.94 to 3.92 × 10 ⁻¹ MPa.

  In the above description, a two-roll coater composed of an applicator roll and a pick-up roll is described as an example. However, the amount of coating liquid pumped up by the pick-up roll between the pick-up roll and the applicator roll. Of course, the present invention may be applied to a roll coater having three or more rolls in which one or two or more mitering rolls (doctor rolls) for adjustment are arranged.

Apply a chromium-free acrylic water-based paint to a hot-dip galvanized steel strip with a thickness of 0.4 mm x width: 1000 mm x length: 1100 to 1300 m using the actual coating device shown in FIG. The incidence of appearance defects due to the liquid was investigated. In addition, the coating is applied by disposing the scattered coating liquid catching plate shown in FIG. 6 at both ends in the length direction as shown in FIGS. It was performed under two conditions: a condition in which the stop was fitted and installed on the edges of the two coater pans (invention example) and a condition in which the spray coating liquid capturing plate was removed (comparative example). .
The above survey results are shown in Table 1. From this result, it can be seen that by using the coating apparatus of the present invention, the appearance defect due to the coating liquid scattering can be almost completely eliminated.

  The coating liquid scattering prevention technology of the present invention is not limited to the galvanized steel sheet coating apparatus as described in the examples, and can be applied to all coating apparatuses that continuously coat the strip. .

1: Strip (steel plate)
2: Applicator roll 3: Pickup roll 4: Coating liquid 5: Coating liquid film 6: Coater pan 11: Edge wiper 12: Scraped coating liquid 13: Coating liquid scattered by vibration of roll opening / closing 14: Scattering coating liquid capture Board 15: Edge blow device

Claims (4)

In the coating device that transfers the coating liquid pulled up from the coater pan with the pick-up roll to the applicator roll, and further transfers the coating liquid from the applicator roll to the surface of the strip,
An edge wiper is brought into contact with the roll surface at both ends of the applicator roll in the body length direction and above the contact portion between the applicator roll and the pickup roll,
A coating apparatus comprising a scattering coating liquid catching plate provided across the edges of two coater pans for the front and back surfaces of a band-like body below both ends of the applicator roll in the body length direction. 2. The splash coating liquid capturing plate according to claim 1, wherein a central portion in a direction connecting the two coater pans is high, and both end portions perpendicular to the direction are formed higher than the central portion. The coating equipment described. The coating apparatus according to claim 1 or 2, wherein the scattering coating liquid catching plate is extendable according to a change in an interval between the two coater pans. The splash coating liquid catching plate is composed of two catching plates individually installed on the edges of the two coater pans, and they form an overlapping portion between the two coater pans, and the length of the overlapping portion. The coating apparatus according to claim 1, wherein the length changes according to an interval between two coater pans.

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