JPH0567341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a steel strip roll coater apparatus for uniformly coating a steel strip with a thin film of a coating liquid at high speed using a roll coater.

[Conventional technology]

Among the equipment that applies paint to the surface of steel strips for special purposes such as protection, decoration, or electrical insulation, roll coater equipment that combines multiple rolls is used for mass production painting. Used a lot. As shown in FIG. 2, for example, a typical roll coater is an applicator that puts paint 6 into a coater pan 5, scoops up the paint 6 with a pick-up roll 3 as it rotates, and makes contact with the pick-up roll 3. The steel strip 1 is coated via a roll 2. 4 is Backup Prowl. Further, the rotation direction of each of the rolls is the direction shown by the arrow in the figure.

[Problem to be solved by the invention]

The above-mentioned roll coater equipment has often been used to coat colored steel sheets with high-viscosity paint in a high film thickness for decorative purposes. Thinner films are progressing, for example, if a paint with a low viscosity of 1.0 to 10.0 cP is required to coat a film thickness in the range of 0.5 to 2.0 μm, the pick-up roll and applicator roll should be rotated at high speed. There is a need to. Furthermore, as line speeds are increased to improve productivity, high-speed coating becomes essential.

In the high-speed rotation range of the applicator roll to support such high-speed coating, it is said that partial liquid drain between the applicator roll and the pick-up roll and bubbles generated in the coater pan are likely to occur. An unstable situation occurs when the liquid is lifted up (scooped up) by picku-a-prol.

Therefore, in order to make the coating thickness uniform when such a roll rotates at high speed, Japanese Patent Application Laid-Open No. 62-210078 was developed.
In JP-A-62-210079, a coating method is proposed in which a nozzle is installed to spray gas onto the roll, and in JP-A-62-210079, a coating method is proposed in which a suction nozzle is installed. The problem is that the technology for uniformly applying the film to a predetermined thickness remains unsolved.

The present invention has been made in view of these conventional problems, and an object of the present invention is to solve the above problems by providing a coater pan with a paint heaping nozzle.

[Means to solve the problem]

This invention provides a coating device that applies roll coating to the surface of a steel strip using a plurality of rolls.
A heaping nozzle is installed on the coater pan to heap up the coating liquid surface of the coater pan along the longitudinal direction of the gap so that the gap just before the rolling contact between the applicator roll and the pick-up roll is constantly filled with the coating liquid over its entire length. This is a roll coater device for the steel strip provided.

[Effect]

Since the present invention is constructed as described above, the paint liquid level in the coater pan is raised along the longitudinal direction between the applicator roll and the pick-up roll just before rolling contact. Since it is raised by the nozzle, even if the above-mentioned rolls rotate at high speed when the viscosity of the coating liquid is low,
Since the coating liquid is supplied to the applicator roll without relying solely on the scooping action of the pick-up roll, problems such as liquid shortage between the two rolls do not occur as in the prior art.

〔Example〕

The present invention will be explained below based on the drawings. FIG. 1 shows an embodiment of the present invention. Note that the same parts as in the conventional example are given the same reference numerals, and redundant explanation will be omitted.

In the roll coater device shown in the figure, the rotational directions of the pick-up roll 3 and the applicator roll 2 are the same as in the conventional example as indicated by the arrows, and the direction of movement of the steel plate 1 and the rotational direction of the applicator roll 2 are opposite to each other. It constitutes a so-called reverse coater. This reverse coating method has the advantage of being able to adjust the coating thickness by changing the peripheral speed of each roll, and is considered the most suitable device for continuous coating of steel strips.

Therefore, as mentioned above, when painting a color steel plate using a high viscosity paint and painting a high film thickness, it was possible to reduce the peripheral speed of each rotor roll.
In order to obtain a thin film in the range of 0.5 to 2.0 μm using a low viscosity paint of 1.0 to 10.0 cP, as in the case of painting steel plates for automobiles, it is necessary to increase the rotation of the applicator roll 2 and the pick-up roll 3. here,
When the viscosity of the paint is low, liquid is likely to run out at the junction between the applicator roll 2 and the pick-up roll 3, which means that the rotation of the pick-up roll must be increased to compensate for the drop.

In addition, when painting at the high rotation speed mentioned above, the viscosity is 1.0~
In order to actually obtain a coating with a film thickness in the range of 0.5 to 2.0 μm at 10.0 cP, the peripheral speed ratio of the applicator roll must be adjusted.
It is necessary to set it to 1.5 to 2.5 as opposed to 1.0 to 1.5, and under such operating conditions, bubbles are drawn in and liquid runs out when the pick-up roll 3 is raised.

Therefore, in the present invention, as shown in FIG.
A pipe 9 with a pump 8 connects the coater pan 5 or other paint tank (not shown) to the nozzle 7.
communicate with. Then, drive the pump 8 to feed an appropriate amount of paint to raise the liquid level of the paint 6 in the coater pan 5, and always fill the space between the pick-up roll 3 and the applicator roll 2 immediately before their rolling contact. This prevents the occurrence of the above-mentioned phenomenon between the rolls in a high rotation range, and makes it possible to stabilize the supply of paint to the applicator roll 2. (Although the same composition is desirable as the fluid that builds up the paint 6, other fluids that do not affect the finish of the paint or coating film may also be used.) Examples are shown below.

Using paint with a viscosity of 1.0 to 10.0 cP, dry film thickness of 0.5 to
Bar coating was carried out within the range of 2.0 μm using the apparatus shown in Figures 1 and 2. When painting at a circumferential speed of 84 m/min, with the conventional equipment shown in Figure 2, bubbles occur over time, causing problems in appearance, and liquid runs out, leaving a part of strip 1 blank. A painted part occurred. On the other hand, in the apparatus according to this embodiment, the gap between the applicator roll 2 and the pick-up roll 3 is always filled with a bulge of paint, so the problem like the above-mentioned conventional example does not occur. A coating of stable quality was obtained.

〔Effect of the invention〕

As explained above, according to the present invention, during high-speed thin film roll coating using low viscosity paint,
The bubble entrainment phenomenon and roll liquid shortage phenomenon that occurred in the conventional example were eliminated, resulting in a significant reduction in defective rate and stabilization of quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment according to the present invention, and FIG. 2 is a schematic diagram of a conventional example. 1... Steel strip, 2... Applicator roll, 3...
...Pitsukatsuprol, 5...Kotapan, 6...
...Coating liquid (paint), 7... Nozzle for heaping up.

Claims (1)

[Claims] 1. In a coating device that applies roll coating to the surface of a steel strip using multiple rolls, the
A roll coater device for steel strip, characterized in that the coater pan is provided with a heaping nozzle for heaping up the coating liquid surface of the coater pan along the longitudinal direction of the gap so that the gap is always filled with the coating liquid over the entire length of the coater pan. .