JPH0418960A - High-speed coating method - Google Patents

Abstract

PURPOSE:To transfer a resin soln. from a roll to a steel strip by disposing the aperture of a nozzle in extreme proximity to the roll surface, supplying the resin soln. to the nozzle to form the pool of the resin soln. in the nozzle aperture and coating the roll by the meniscus formed between the nozzle and the roll. CONSTITUTION:The nozzle 2 for coating with the resin is disposed in proximity to the coating roll 4 and the resin soln. is supplied to the nozzle 2. The surface of the roll 4 is coated by the meniscus formed between the nozzle and the roll 4. Further, the coating on the surface of the roll 4 is transferred to the surface of the steel strip 5. The steel strip 5 is pinched by a back up roll 6 and the coating roll 4 in order to assure the adhesive property between the coating roll and the steel strip. The uniform coatability is further improved if the gap between the nozzle 2 and the roll 7 is precisely controlled by disposing an intermediate roll (metallic roll) 7. The final products are obtd. inexpensively in a large amt. and the efficient dealing with an increase in demand is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for coating a preformed resin film at high speed.

Hot-rolled steel sheets, cold-rolled steel sheets, Zn, Sn, Pb, and alloy-coated steel sheets of these metals are coated with resin and are widely used as materials for construction, electrical equipment, and cans. , improving quality and productivity is important.

(Conventional technology) The conventional resin coating method is to coat the steel strip with alkali,
After cleaning the surface by pickling or the like, or after chemical conversion treatment, a so-called roll coater method is generally used, in which a solution of the resin to be coated is continuously coated on the steel strip using a roll. This method involves putting the resin solution in a container called a pan, and then placing it in a container called a pan. The resin solution is scooped up from a pan using a fan roll and transferred to an application roll that comes into contact with the steel strip to coat the steel strip. The film thickness is controlled by adjusting the circumferential speed of the pink unroll, the circumferential speed of the application roll, the gear knob between the rolls, and the web running speed, and is controlled to keep the viscosity of the resin solution constant during coating.

Such a roll coater method is a coating method widely used today, and materials coated on steel sheets or surface-treated steel sheets are used for cans, construction, and electrical equipment.

(Problem to be solved by the invention) The disadvantage of this roll coater method is that coating defects such as scratches and dents are likely to occur especially during high-speed coating due to bubbles in the resin solution when picked up from the pan. However, there is a limit, and an example of high-speed painting is said to be a line speed of 100 to 150 m/min.
). A curtain flow coater has been proposed and put into practical use as a method to solve the drawbacks of this boring roll coater. This method does not use rolls that come into contact with the steel strip, but instead pours the resin solution from a slit in a curtain shape and applies it to the moving steel strip. Because no rolls are used, there are no coating defects such as repellents or dents, and the film is uniform. Excellent in sex. Although it has such advantages, in terms of efficiency, the steel strip running speed is 100 to 160 m/win as an example of high speed (Tadashi Matsudaira; [Industrial Painting Technology J 477, Koshobo Publishing (197
7) ), there are limits. This is because the air carried by the rope gets caught up in the resin solution at the point of contact between the curtain and the steel strip, causing paint film breakage. There is also a method of controlling the film thickness by immersing the steel strip in a resin solution or spraying the resin solution onto the steel strip and then squeezing out the excess resin solution.
If the speed exceeds m/min, there is a limit to increasing the speed because the resin solution that has been squeezed out will scatter violently and become soot that will stick to the steel strip, or bubbles caused by gas being drawn into the resin solution will lead to coating defects. was there.

Next, U.S. Patent No. 3,201,275 discloses a method that solves the above problem, but this method uses capillary action to suck up the resin solution from the resin solution whose liquid level is lower than the coating nozzle. Coating is performed by forming a meniscus of resin solution on the nozzle and contacting it with the tape. This method causes the following problems. As the running speed of the steel strip increases, the rate of supply of the resin solution to be supplied increases accordingly, and coating film breakage occurs on the coated surface due to an insufficient amount of resin solution sucked up by capillary action. It is easy to imagine that sufficient liquid can be supplied if the resin solution is supplied using a known metering pump, but even in this case, the atmospheric gas (air for boat fishing) carried by the high-speed steel strip causes a meniscus. The paint film breaks due to collision with the meniscus and air being drawn into the meniscus.
There are limits to high speed coating.

(Means for Solving the Problems) The present inventors have completed the present invention as a result of various studies on high-speed resin coating methods. That is, a coating roll is placed in contact with the coating surface of a running steel strip, the opening of a nozzle is brought very close to the roll surface, and a resin solution is supplied to the nozzle so that the resin/8 solution is applied to the nozzle opening. Developed a high-speed coating method characterized by forming a pool, applying the required amount of coating to the roll using a meniscus formed between the nozzle and the roll, and transferring the resin solution from the roll to the steel strip. This is what I did.

The present invention will be explained with reference to FIG. 1 showing an embodiment thereof.

In the present invention, a solution or emulsion of water or an organic solvent containing the resin to be coated is supplied to a nozzle 2 from a known metering pump or pressurized extrusion container, and the nozzle 2 is provided with a slit-like opening 3. A coating roll 4 is disposed close to the opposite side of the slit opening 3, and the rope 5 to be coated with resin is made to run in contact with the roll 4. At this time, the steel strip 5 is sandwiched between the coating roll 4 and the support roll 6 so that the coating roll and the steel strip can be brought into close contact with each other. The problem with placing the nozzle directly close to the steel strip without using a coating roll is that the gap between the nozzle and the strip should be 1 mm or less, or even 0.1 m.
Although accuracy of less than m is required, in actual operation it is difficult to achieve close proximity due to the flatness (plate shape) of the steel strip. That is, the edge side elongation of the steel strip (referred to as "ear wave")
In addition, if the steel strip has a shape that is elongated at the center (referred to as "medium elongation"), it is difficult to obtain a completely flat surface even if the support roll is pressed against the steel strip, so the nozzle must be placed close to the steel strip. becomes difficult. It was also experimentally confirmed that when the nozzle was moved away from the steel strip, the coating became streaky and a uniform coating film could not be obtained.

Therefore, when considering actual operation, the method using a coating roll according to the present invention is suitable. According to this property, the gap between the nozzle and the coating roll of 0.1 to 0.5 mm, which is a condition for uniform coating, can be easily set and is not affected by the shape (flatness) of the steel strip. In addition, the amount of adhesion is controlled by the amount of resin solution discharged from the nozzle (cc/m
This is a simple control method in which the wet adhesion amount is the value (cc/M2) obtained by dividing 1n) by the running speed of the mesh strip (m/1Ilin) and the coating width (m2) of the steel strip. It is easier to obtain a uniform coating surface if the direction of rotation of the coating roll is opposite to the running direction of the steel strip. The peripheral speed of the coating roll is determined by the viscoelasticity of the resin solution to be applied and the running speed of the rope, and the ratio of the roll peripheral speed to the rope running speed is usually 1.1 to 6.
, 0.

Next, the present invention will be explained with reference to Examples.

(Example) Fig. 1 shows an example of the method of implementing the present invention, in which a steel strip 5
The surface is cleaned by alkaline degreasing or further pickling treatment, and examples of nozzle arrangement for horizontal travel (a) and vertical travel (a) are also shown. Coating roll 4 with resin coating nozzle 2
The resin solution is supplied to the nozzle 2 and the meniscus formed between the nozzle 2 and the roll 4 coats the surface of the roll 4. Furthermore, the coating on the surface of the roll 4 is transferred to the surface of the steel strip 5. Further, in order to ensure adhesion between the coating roll and the steel strip, [F5] is sandwiched between the hack-up roll 6 and the coating roll 4. A rubber roll is used as the coating roll 4 due to its adhesion to the steel strip, but if an intermediate roll (metal roll) 7 is arranged and the gear knob between the nozzle 2 and the roll 7 is precisely controlled, uniform coating properties can be further improved.

An example in which a water-soluble resin is coated in such a device configuration will be described. The net belt 5 has a thickness of 0.2 mm and a width of 500 mm.
The resin coating nozzle 2 used had a slit-like opening 3 with a gap of 0.5 mm and a width of 490 mm. The coating roll 4 used had a width of 600 mm and a roll diameter of 200II1 m, and the gap with the nozzle was set to 0.1 m+n. The backup roll 6 used had a width of 600 am and a diameter of 400 wnO.

The coating roll 4 was rotated in the opposite direction to the running direction of the steel strip (reverse coating), and the peripheral speed of the roll was set to be 1.5 times the running speed of the steel strip. Steel strip running speed is 300 m/win
A wet coating with a thickness of 20 mm was applied. At this time, in order to investigate the influence of the shape (flatness) of the steel strip, a steel strip with wavy edges (ear wave) with a wave height of 2 cm and a wave pitch of 100 mm was used. At the part where the steel strip and the coating roll are in contact, the steel strip and the coating roll come into close contact linearly in the width direction of the wire strip, so uniform coating was possible regardless of the shape of the wire strip.

For comparison, coating was carried out with the nozzle close to the steel strip. At this time, in order to stabilize the running of the steel strip, the steel strip was supported by a hack-up roll 6, and the nozzle 2 was brought close to the steel strip 5. When a steel strip having the shape of the above embodiment is passed through with the gear and bulge between the net strip 5 and the nozzle 20 being 0.1 mm, the steel strip does not have perfect flatness even on the bank unroll, and the steel strip edges are It contacted the nozzle and a uniform coating could not be obtained. Furthermore, as the nozzle was moved away from the steel strip, the coating became streaky, and a uniform coating could not be obtained.

(Effects of the Invention) Since the high-speed coating equipment for resin solution that implements the present invention can be installed within the Metsuki line, the present invention makes it possible to obtain final products in large quantities at low cost, making it possible to efficiently meet the recent increase in demand. I can handle it well.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are explanatory views showing an embodiment of the present invention, and FIGS. 2(a) and 2(b) are explanatory views showing an embodiment of a comparative example. DESCRIPTION OF SYMBOLS 1...Resin liquid, 2...Nozzle, 3...Slit-shaped opening, 4...Coating roll, 5...fi!
, 6... Hashikuasobrol, 7... Intermediate roll (
metal roll). Figure 2

Claims (2)

[Claims] (1) A coating roll is placed in contact with the coating surface of a running steel strip, and the nozzle opening is brought very close to the roll surface, and a resin solution is supplied to the nozzle so that a pool of resin solution is formed at the nozzle opening. A high-speed coating method, characterized in that a meniscus formed between a nozzle and the roll coats the roll in the required amount, and a resin solution is transferred from the roll to the steel strip. (2) A coating roll is placed in contact with the coating surface of the running steel strip, and an intermediate metal roll is placed in contact with the coating roll, and the nozzle opening is brought very close to the intermediate metal roll surface, and the resin solution is applied to the nozzle. to form a puddle of resin solution at the nozzle opening,
A meniscus formed between the nozzle and the intermediate metal roll applies the required amount of coating to the intermediate metal roll, transfers the resin solution from the intermediate metal roll to the coating roll, and then transfers the resin solution from the coating roll to the steel strip. A high-speed coating method characterized by transferring.