JPS63143961A - Coating device for plate material - Google Patents

Abstract

PURPOSE:To coat a film stably, by placing the roll surface of an applicator roll at the lower end of a blade and bringing it into contact with a plate material in a device in which a plurality of rolls and a blade are disposed. CONSTITUTION:A coating material P supplied between a rotating transfer roll 1 and a doctor roll 2 is discharged out of a gap between the both rolls 1 and 2 and adhered to the surface of the transfer roll 1. The adhered coating material P moves in accordance with the rotation of the roll 1 and is scraped by a blade 8. The scraped coating material P flows down along the surface of the blade 8, adhered to the applicator roll 3 and moves in accordance with the rotation of said roll 3. The coating material P is transferred to a steel plate S running from the applicator roll 3 to form a coated film F. As a result, even if the coated film is of 20mum thickness or less, film curtain is never cut off to carry out a stabilized coating.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an apparatus for continuously coating a traveling board. The present invention is applied to coating steel plates and other cut plates or coiled plates.

(Prior Art) Roll coater type coating equipment is widely used for continuous coating of plate materials such as steel plates.

An example of such a roll coater type coating apparatus is disclosed in Japanese Patent Publication No. 60-56552. As shown in FIG. 2, this coating device consists of a backup roll 4 on which a strip S is wound, a pickup roll 5 whose lower part is immersed in paint P in a paint pan 9, and a pickup roll with a required gap. 5 and is provided with an applicator roll 3 that is in contact with the strip S. Then, the paint P in the paint pan 9 adheres to the rotating pickup roll 5, and the adhered paint P passes through the applicator roll 3 and is applied to the strip S wound around the backup roll 4.

Another coating method is a curtain coater type, and the outline of the apparatus is shown in FIG.

As shown in the drawing, a paint P whose viscosity has been adjusted in advance is supplied to a roll gap between a painted rubber roll 6 and a metal doctor roll 2, discharged, and scraped off with a blade 8 brought into contact with the painted rubber roll 6. The scraped paint P flows down along the blade 8 to form a paint curtain C, and is applied to the object S to be painted (in this example, a cut steel plate) passing under the blade. A predetermined coating film thickness is obtained by adjusting the roll gap, sheet passing speed, and circumferential speed of the doctor roll 2 and coating rubber roll 6. The doctor knife 7 completely scrapes off the paint P adhering to the doctor roll 2.

(Problems to be Solved by the Invention) In the coating apparatus disclosed in Japanese Patent Publication No. 60-56552, the pickup roll and the applicator roll perform so-called natural rotation. That is, both rolls are rotating in opposite directions, and at the position where the circumferential surfaces of both rolls meet, the circumferential surfaces of the two rolls are moving in the same direction. As a result, cavitation and filamentation occur in the exit region of the roll gap between both rolls, causing foaming due to the inclusion of air and a stringing phenomenon. This threading phenomenon causes streak-like unevenness in the paint adhering to the surface of the applicator roll, and the unevenness is transferred to the coating surface of the strip, impairing the smoothness of the coating surface. Furthermore, in order to prevent the above-mentioned unevenness, the circumferential speeds of the pickup roll and the applicator roll and the range of adjustment of the roll gap between the pickup roll and the applicator roll are limited.

In addition, in the curtain coater, even if the coating film thickness adjustment conditions such as sheet passing speed, roll gap, and roll circumferential speed are adjusted appropriately, the thinnest film is about 25 μm (hereinafter referred to as dry film thickness). The current situation was that it was only possible to obtain it stably. In other words, in a curtain coater, the coating film thickness is determined by (discharge amount from the roll gap)/(sheet passing speed). Therefore, when coating a thin film of about 20 μm, for example, the roll gap and the circumferential speeds of the doctor roll and coating rubber roll are first adjusted to extremely reduce the amount of paint discharged from the roll gap. If the predetermined coating film thickness is still not achieved even after this, the plate passing speed is increased to reduce the coating film thickness. However, if the sheet threading speed is increased, the wind pressure caused by the traveling copper sheet may hit the paint curtain, causing the paint curtain to shake, or the paint curtain may be pulled by the traveling steel sheet and be cut.

For these reasons, it was not possible to form a stable thin film coating using a curtain coater.

(Means for Solving the Problems) The coating device of the present invention includes a transfer roll, a doctor roll that is close to the transfer roll with a required gap and rotates in the same direction as the transfer roll, and a doctor roll that rotates in the same direction as the transfer roll. and a contacting blade. The applicator roll is arranged such that its roll surface contacts or approaches the lower end of the blade and also contacts the plate material.

(Operation) The paint supplied between the rotating transfer roll and doctor roll is discharged from the gap between the two rolls and adheres to the transfer roll surface. The adhered paint moves with the rotation of the transfer roll and is scraped off by the blade. The scraped paint flows down along the blade surface, adheres to the applicator roll, and moves as the applicator roll rotates. Then, the paint is transferred from the applicator roll to the traveling plate, and a coating film is formed on the plate. The coating film thickness is adjusted by adjusting the roll circumferential speed and roll gap.

Since the paint is supplied between the transfer roll and the doctor roll which are rotating in the same direction, and is discharged from the gap between the two rolls, streak-like unevenness is unlikely to occur in the paint adhering to the transfer roll. Further, when the paint layer on the surface of the transfer roll becomes thick, thin undulation-like unevenness may occur. In this case, as the paint flows down the blade surface, the paint film is smoothed by the surface tension of the paint. Therefore, it will not cause uneven growth on the coating film of the product.

Furthermore, since the paint is immediately transferred from the blade to the applicator roll, the paint curtain will not be disturbed by the wind pressure caused by the running of the plate, and the tension caused by the running of the steel plate will not act on the paint curtain. As a result, even with a coating film thickness of 20 μm or less, coating can be performed stably without causing paint curtain breakage.

(Embodiment) FIG. 1 shows an embodiment of the present invention, and is a block diagram of a board coating apparatus.

As shown in the drawing, the coating equipment includes transfer roll 1,
It is equipped with four rolls: a doctor roll 2, an applicator roll 3, and a backup roll 4. The transfer roll 1 and the doctor roll 2 are close to each other with a required gap. The applicator roll 3 is located below the transfer roll 1 and is placed in contact with the steel plate S. The backup roll 4 is located directly below the applicator roll 3, and the steel plate S to be painted is wound around it. A payoff reel for feeding out the steel plate S is disposed on the upstream side of the backup roll 4, and a tension reel (both not shown) for winding up the steel plate S is disposed on the downstream side.

Transfer roll 1, doctor roll 2, applicator roll 3, and backup roll 4 are all rotationally driven in the same direction by an electric motor (not shown).

Further, the doctor roll 2 is rotatably supported by a horizontally movable bearing stand (not shown). Transfer roll 1 and doctor roll 2 by displacing the bearing stand
Adjust the roll gap between.

The coating device is equipped with a doctor knife 7 whose cutting edge is in contact with the doctor roll 2. The doctor knife 7 extends along the two axial directions of the doctor roll, and scrapes off the paint P adhering to the surface of the doctor roll 2. Further, a blade 8 for scraping off the paint P is arranged near the lower end of the transfer roll 1 and is fixed in a vertical position. The blade 8 extends along the roll width direction and is in contact with the transfer roll surface.

In the coating apparatus configured as described above, paint P is supplied between the rotating transfer roll 1 and doctor roll 2. The supplied paint P protrudes from the gap between both rolls and adheres to the transfer roll surface. The adhered paint P moves with the rotation of the transfer roll 1 and is scraped off by the blade 8. The scraped paint P flows down along the blade, adheres to the applicator roll 3, and moves as the applicator roll 3 rotates. Then, the paint P is transferred from the applicator roll 3 to the traveling steel plate S, and a coating film F is formed on the steel plate S.

Here, an example of coating by the above-mentioned coating apparatus will be explained.

The coating conditions were as follows.

Viscosity of paint used = 50 to 140 seconds (Solid content of paint used in Ford Cup = 25 to 50 Main line speed + 40 m/min Roll peripheral speed ratio Applicator roll: 1.0 to 2.0 Transfer roll: 0.5 to 3. 0 Doctor roll: 0.1~0.5 0-le gap (mm) Transfer/Doctor: -0,3~-0,5 Applicator/Backup: -0,1~-0,5 Dry film thickness: 5~ 40 μm As a result of coating under the above coating conditions, a smooth product with no surface defects was obtained.

Table 1 shows examples in which various dry film thicknesses were obtained by changing coating conditions.

Table 1 (Effects of the Invention) According to the coating device of the present invention, the coating surface has excellent smoothness,
A product without coating defects can be obtained. Also, 20I
Even if the coating film thickness is less than Jm, continuous coating can be performed stably without causing paint curtain breakage.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of a conventional plate coating apparatus. 1... Transfer roll, 2... Doctor roll, 3... Applicator roll, 4... Backup roll, 5... Pick up roll, 6... Painted rubber roll, 7... Doctor knife, 8...Blade, 9...Paint pan.

Claims (1)

[Claims] A transfer roll, a doctor roll that is close to the transfer roll with a required gap and rotates in the same direction as the transfer roll, and a blade whose upper end is in contact with the transfer roll, and is configured to rotationally drive the transfer roll and doctor roll. In this painting method, paint is supplied between both rolls, the paint adhering to the transfer roll is scraped off, and the scraped paint flows down along the blade surface to adhere to the moving board. 1. A coating apparatus for a plate material, characterized in that a roll is disposed such that its roll surface is in contact with or close to the lower end of the blade and in contact with the plate material.