JPH0780396A - Coating method of plate material - Google Patents

Abstract

PURPOSE:To provide the coating method of plate materials capable of uniformly applying a coating material film of double layers thereon without mixing. CONSTITUTION:Coating materials are made to flow out of plural slits 19a, 19b which are opened at the sliding surface 13 of a slide hopper type coating device apart spacings formed forward and backward and extend in the width direction of the sliding surface. The plural coating material films are superposed on each other on the sliding surface to form a double layered coating material film. The double layered coating material film is allowed to fall freely from the front end of the sliding surface 13 to form a coating material curtain P. The coating materials are allowed to flow out of the slits 19a, 19b at the width exceeding the plate width and guide liquids are allowed to flow out of slits 20a, 20b, 21a, 21b separate from the slits 19a, 19b out of which the coating materials flow to both outer sides of the double layered coating material film so as to come into contact with the side edges of the double layered coating material film on the sliding surface 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a plate material, and more particularly to a method for coating a plate material in which a multi-layer paint film is simultaneously formed on the surface of the plate material.

The present invention is used in a continuous coating line for metal plates such as steel plates, aluminum plates and copper plates, plastic plates, cut plates such as wood plates or strip-shaped plates.

[0003]

2. Description of the Related Art A plate material such as a steel plate surface is coated with an organic film on the surface of the steel plate for the purpose of imparting an anticorrosive effect, electrical insulation, or design. As for the coating of the plate material, the pre-coating has been in progress from the post-molding coating (post coating). In addition, as the demand for quality of coated plate materials becomes higher and higher in functionality, the coating film is becoming multi-layered due to the functional differentiation of the coating film.

As a method for coating a plate material in which a multi-layer paint film is simultaneously formed on the surface of the plate material, for example, Japanese Patent Publication No. 49-24.
There is a coating method disclosed in Japanese Patent No. 133 publication. In this method, the paint is laminated on the slide surface of the slide hopper type coating device, and the multi-layer paint is allowed to fall freely from the tip (lip part) of the slide surface to form a vertical paint curtain. Freely drop on the surface and apply paint to the plate.

The coating method using the slide hopper type coating apparatus has the advantages that the multi-layer coating process can be simplified, the schedule can be made free, and the basic unit of the coating can be reduced, and the manufacturing unit cost of the multi-layer coating plate can be reduced.

[0006] Coating of a steel sheet or the like is performed for the purpose of protecting the surface from rust and the like, or for the purpose of designing. Therefore, it is necessary to form a uniform coating film on the entire metal surface. But,
In the coating method by the slide hopper type coating device,
Since the film thickness of the paint curtain in the vicinity of the curtain guide tends to be thicker than the film thickness in the central part of the curtain, the paint is applied thicker than the other parts on both side edge portions of the plate material. Therefore, in the technique disclosed in the above publication, a brush is provided at the lower end of the rod-shaped curtain guide in order to expand the paint curtain. The brush is in contact with the plate material and spreads the excessively applied paint on the side edges to make the paint film uniform.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the method proposed in Japanese Patent Publication No. 133, since the front end portion of the curtain guide contacts the surface, the entire surface of the curtain guide cannot be coated. Further, even if the curtain guide is installed at both ends in the width direction of the plate material, since the tip end portion of the curtain guide has a brush shape and the paint in the portion in contact with the brush is mixed, the multilayer paint film is destroyed, The coating film could not exhibit its full function.

Further, in order to avoid the excessive coating and mixing of the above-mentioned paint on the side edges of the plate, it is possible to make the paint curtain width sufficiently larger than the plate width. It is useless. If the paint is a single layer, the paint that has flowed down can be collected and reused. However, in the case of multiple layers, the paints are mixed and cannot be reused. If the paint is expensive, the losses due to the waste of the paint can be very high.

The present invention is intended to provide a method for coating a plate material which can be applied uniformly without mixing a multi-layer paint film.

[0010]

In the method for coating a plate material according to the present invention, a slide hopper type coating device is used to open the slide surface at a front and rear intervals with a plurality of slits extending in the width direction of the slide surface to allow the paint to flow out. , A plurality of paint films are laminated on a slide surface to form a multi-layer paint film, and the multi-layer paint film is allowed to freely fall from the tip of the slide surface to form a paint curtain, and the paint curtain is formed on the surface of a running plate material. Is dropped to form a multi-layer paint film on the surface of the plate material. The paint is made to flow out from the slit in a width exceeding the plate width. And
The guide liquid is caused to flow from the slit other than the slit through which the paint flows out to both outsides of the multilayer paint film so as to contact the side edges of the multilayer paint film on the slide surface.

The width of the paint flowing out from the slit is determined in consideration of the variation of the plate width and the meandering amount of the plate material during running.
If the outflow width is too wide, the amount of paint waste increases, which is not economical. Therefore, the outflow width is slightly wider than the plate width, and for example, about 1.02 to 1.20 times the plate width is suitable. It is desirable that the physical properties (viscosity, surface tension, specific gravity) of the guide liquid are almost the same as those of the paint. For example, recovered paint or waste paint is used as the guide liquid. Further, it is desirable that the guide liquid flow at a flow rate almost equal to that of the coating material and flow in a laminar flow state like the coating material.

[0012]

Since the paint flows out from the slit in a width exceeding the plate width, the paint flows down uniformly over the entire width of the plate. Therefore, the paint that has dropped onto the surface of the plate material does not rise up at the edge portion on the plate side. Further, since the guide liquid flows in contact with both side edges of the multi-layer paint film on the slide surface and the paint curtain, both side edges are restricted by the guide liquid. Therefore, the flow of the paint is stable at both side edges of the paint curtain as in the central part.

[0013]

1 and 2 show an example of a coating apparatus for carrying out the method of the present invention. Figure 1 shows a wide steel plate
Further, FIG. 2 shows a state in which a narrow steel plate is coated.

The coating device 11 is a two-layer slide hopper type coating device and coats a strip-shaped steel plate S. The upper surface of the slide hopper 12 is a slide surface 13 that is inclined forward. Inside the slide hopper 12, paint supply holes 15a and 15b are provided as a set, and paint / guide liquid supply holes 16a and 16b and guide liquid supply hole 17 are provided.
a and 17b are sequentially provided from the front. Paint slits 19a, 19b from the paint supply holes 15a, 15b, paint / guide liquid slits 20a, 20b from the paint / guide liquid supply holes 16a, 16b, and guide liquid supply holes 17a, 1
The guide liquid slits 21a and 21b extend vertically from 7b,
The slide surface 13 has an opening. Paint slit 19a,
The width of 19b is slightly wider than the minimum width of the steel plate S to be coated. The paint / guide liquid slits 20a and 20b are located at positions where both ends of the paint slits 19a and 19b are added, and when combined with the paint slits 19a and 19b, they are slightly wider than the maximum width of the steel plate S to be coated. The guide liquid slits 19a, 19b are the paint / guide liquid slits 20a,
It is in a position where both ends of 20b are added. A gear pump (not shown) for quantitatively feeding the paint or the guide liquid is connected to the paint supply hole 15 and the paint / guide liquid supply holes 16a and 16b, so that the paint and the guide liquid can be switched. . A gear pump (not shown) that quantitatively sends the guide liquid is connected to the guide liquid supply holes 17a and 17b.

A case where a wide steel plate S is coated in the coating apparatus constructed as described above will be described. The paint is supplied to the slide hopper 12 through the paint supply holes 15a and 15b.
Through the paint slits 19a, 19b,
It is supplied from the guide liquid supply holes 16a and 16b to the slide surface 13 through the paint / guide liquid supply hole slits 20a and 20b. The paint is uniformly supplied to the slide surface 13 in the width direction,
Two layers are superposed on the slide surface. At this time, the primer coating material is supplied from the coating material supply hole 15a in the first stage to the coating material slit 19a, and the coating material slit 1 is supplied from the coating material supply hole 15b in the second stage.
The top coat paints are respectively supplied to 9b. paint/
The same applies to the guide liquid supply holes 16a and 16b. In addition, the guide liquid slits 2 are provided from the guide liquid supply holes 17a and 17b.
A guide liquid is supplied to 1a and 21b. The two-layer paint film falls freely at the tip of the slide surface 13 to form a paint curtain P. Guide roll 23 below the slide hopper 12
The steel sheet S is running under the guidance of, and the paint curtain P falls on the surface of the steel sheet S to form a two-layer paint film on the surface of the steel sheet S. The guide liquid L flowing down while restraining both side edges of the paint curtain 9 is collected in the pan 25. The steel sheet S on which the two-layer paint film is formed is heated in a heating furnace, and the paint is dried and cured.

When coating a narrow steel plate S, the paint is uniformly supplied in the width direction from the paint supply holes 15a, 15b of the slide hopper 12 through the paint slits 19a, 19b to form two layers on the slide surface. Overlaid. At this time, the primer paint is supplied from the paint supply hole 15a in the former stage to the paint slit 19a, and the paint supply hole 15b in the latter stage.
The top coat paint is supplied to the paint slits 19b from each. Also, the paint / guide liquid supply holes 16a, 16b
From the paint / guide liquid supply hole slits 20a, 20b, from the guide liquid supply holes 17a, 17b to the guide liquid slit 21a,
The guide liquid is supplied to each of 21b.

A specific example of the coating method according to the present invention will be described. In the state of the coating apparatus shown in FIG. 1, coating for forming a two-layer coating film was performed. The width of the sliding surface is 16
The height from the tip of the sliding surface to the steel plate surface was set to 150 mm. The original plate is an electrogalvanized steel plate, and the width of the steel plate is 1320 mm.

As the paint, a polyester-based primer paint was used for the lower layer, and a polymer polyester-based topcoat paint was used for the upper layer. The thickness of the coating when dried is 5 for the lower layer.
μm and the upper layer was 20 μm, and two layers were simultaneously coated. The recovered paint was used as the guide liquid. The width of the guide liquid is 1 each
It was 50 mm. The coated steel sheet was baked in an induction heating furnace. The coating film of the steel sheet coated by the coating device had a uniform film thickness in the width direction, and each layer was applied without mixing even at the end portion.

The present invention is not limited to the above embodiment. For example, the feeding direction of the plate material may be opposite to that in the above embodiment. Further, the number of slits may be increased to eight or more. This makes it possible to apply three or more layers simultaneously or to cope with three or more types of plate widths.

[0020]

According to the method of coating a plate material of the present invention, the paint that has fallen on the surface of the plate material does not rise at the edge portions of the plate, and the flow of the paint is the same at both edge portions of the paint curtain as in the central portion. Is stable. Therefore, the paint can be applied uniformly without mixing. Further, since the width of the paint curtain can be made closer to the width of the plate, the amount of waste paint that flows down the outside of the side edge of the plate is reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a coating apparatus for carrying out the method of the present invention and showing a coating state of a wide plate material.

FIG. 2 is a perspective view showing a coating state of a narrow plate material by the coating device.

[Explanation of symbols]

 11 Coating Equipment 12 Slide Hopper 13 Sliding Surface 15a, 15b Paint Supply Hole 16a, 16b Paint / Guide Liquid Supply Hole 17a, 17b Guide Liquid Supply Hole 19a, 19b Paint Slit 20a, 20b Paint / Guide Liquid Slit 21a, 21b Guide Liquid Slit 23 Guide Roll 25 Pan L Guide Liquid P Paint Curtain S Steel Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kanai 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Corp. Corporate Technology Development Division

Claims (1)

[Claims] 1. A slide hopper type coating device is provided with a plurality of slits extending in the width direction of a slide surface to allow the paint to flow out by opening the slide surface at a front-rear interval and superposing a plurality of paint films on the slide surface. A multi-layer paint film is formed.The multi-layer paint film is freely dropped from the tip of the slide surface to form a paint curtain, and the paint curtain is dropped on the surface of a running plate material to form a multi-layer paint film on the surface of the plate material. In the method of coating a plate material to be formed, the paint is flowed out from the slit with a width exceeding the plate width, and a guide liquid is applied to the side edge of the multilayer coating film on the slide surface from a slit different from the slit from which the paint flows A method of coating a plate material, which comprises contacting and flowing out to both outsides of a multilayer coating film.