JP2709971B2 - High-speed resin partial coating method - Google Patents

Description

The present invention relates to a method for partially coating a steel sheet with a resin film at a high speed, and relates to a hot-rolled steel sheet, a cold-rolled steel sheet, Zn, A
Efficiently obtain partial coating materials suitable for processing (especially welding joining) of materials for architectural, electrical equipment and cans resin-coated on alloy-coated steel plates of l, Sn, Pb and these metals It is assumed that.

(Prior art) As a conventional resin coating method, after a steel strip is cleaned on its surface with alkali, pickling, or the like, or after a chemical conversion treatment, a solution of a resin to be coated is continuously coated on the steel strip by a roll. The so-called roll coater method is generally used. In this method, a resin solution is put into a container called a pan, the resin solution is scooped up from a pan by a pickup roll, and the resin solution is transferred to an application roll that comes into contact with the steel strip to coat the steel strip. The film thickness is adjusted by adjusting the peripheral speed of the pickup roll, the peripheral speed of the application roll, the gap between the rolls, and the running speed of the steel strip, and is controlled so that the viscosity of the resin solution is kept constant during coating.

Such a roll coater method is a coating method widely used today, and a material coated as it is on a steel sheet or on a surface-treated steel sheet is used for cans, construction, and electric equipment.

(Problems to be Solved by the Invention) The drawbacks of this roll coater method are that the pattern of the roll eyes is easily generated as called roping eyes, and coating defects such as cissing and dents due to bubbles of the resin solution when picked up from the bread. Especially, it is easy to occur at the time of high-speed coating.
It is said to be 50m / min (Tadashi Matsudaira; "Industrial coating technology" 4
77, Koshobo Publishing (1977)). In addition, the application roll that comes into contact with the steel strip is flawed at the end of the steel strip, and it is necessary to perform an operation to gradually reduce the width from a wide steel strip to a narrow steel strip, that is, schedule management. When changing, it took a long time for cleaning and preparation, and there was also a problem in workability. In addition, in order to perform partial coating in consideration of welding, it is a general method to provide a groove in a roll so as to leave an uncoated portion. Here, as an example, in the case of a material for cans, the position of the uncoated portion on the steel strip changes because the size of the can changes according to the capacity of the can. Preparation costs for various types of grooving rolls were high and inefficient.

As a method of solving such a drawback of the roll coater, a curtain flow coater has been proposed and put to practical use. This method applies the resin solution to the running steel strip by flowing the resin solution from the slit in a curtain shape without using the roll in contact with the steel strip.Since no roll is used, there is no coating defect such as roping eyes, repelling, dents, etc. Excellent film uniformity. In addition, since a roll is not used, schedule control is not required for width variations of the steel strip, and quick switching is possible by providing a plurality of slits when changing the type of resin. Despite these advantages, in terms of efficiency, the running speed of the steel strip is 100 to 160 m / mi as a high speed example.
n (Tadashi Matsudaira; "Industrial Coating Technology" 477, Koshobo Publishing (1977)), with limitations. This is because the air carried by the steel strip is caught in the resin solution at the contact point between the curtain and the steel strip, and the coating film breaks. Further, since there is no control means for leaving a non-coated portion with respect to the partial coating, the partial coating cannot be performed by this method.

There is also a method of controlling the film thickness by immersing the steel strip in the resin solution, or spraying the resin solution on the steel strip and then spraying the excess resin solution by the gas drawing method. However, the line speed (steel strip running speed) is 160 m / min. At this point, the squeezed resin solution is violently scattered and splashed to adhere to the steel strip, and foaming due to entrainment of gas into the resin solution leads to coating film defects, so that there was a limit to speeding up. Further, with respect to the partial coating, there is no control means for leaving a non-coated portion, so that even this means cannot perform the partial coating.

Next, U.S. Pat.No. 3,201,275 proposes a method for solving the above problem, but this method sucks up a resin solution from a resin solution having a liquid level lower than that of a coating nozzle by a capillary phenomenon and causes the coating nozzle to melt the resin solution. The coating is performed by forming a meniscus and contacting the tape. This method has the following problems. When the running speed of the steel strip is increased, the supply speed of the resin solution to be supplied is correspondingly increased, and the coating surface is cut off due to insufficient suction of the resin solution due to the capillary phenomenon. It is easily conceivable that a sufficient amount of liquid can be supplied if the resin solution is supplied by a known metering pump. However, even in this case, the atmospheric gas (generally, air) carried by the high-speed steel strip causes the meniscus portion. And the air is drawn into the meniscus, causing a break in the coating film, which limits the high-speed coating. Also in this method, there is no means for controlling and leaving the non-coated portion, and partial coating is impossible.

An object of the present invention is to provide a high-speed resin partial coating method which can completely eliminate the disadvantages of the conventional method as described above.

(Means for Solving the Problems) As a result of various studies on the high-speed resin coating method, the present inventors have completed the present invention. That is, according to the present invention, a nozzle is arranged on a coating surface of a traveling steel strip, an opening of the nozzle is brought very close to the steel strip, and a resin solution is supplied to the nozzle to supply a resin solution to the nozzle opening. In a method of forming a pool and performing coating by a meniscus formed between a resin solution and a steel strip,
When the discharge amount from the nozzle x (liter / minute), the nozzle slit opening width s (millimeter), the steel strip width direction application width w (mm), and the distance y between the nozzle opening and the steel strip (millimeter), In addition, the gas suction port is disposed well above the nozzle in the running direction of the steel strip, and the suction port is divided into multiple parts in the width direction of the steel strip to suck the steel strip carrier gas only at the position to be coated. The gist is a characteristic high-speed resin partial coating method.

y · s · w · 60 / x ≦ 30000 FIG. 1 (a) showing an embodiment of the present invention.
Description will be made based on (b).

 An embodiment of the present invention is configured as follows.

A solution of water or an organic solvent or an emulsion liquid 1 containing a resin to be coated is supplied from a known metering pump or a pressurized extrusion container to a nozzle 2 provided with a slit-shaped opening 3. The steel strip 5 to be resin-coated is supported by the opening 3 through the support roll 4 provided on the side.
Run close to. The nozzle 2 is provided with a suction port 6 on the upper side of the opening 3 in the running direction of the steel strip, and sucks an atmospheric gas conveyed accompanying the running of the steel strip. The suction port 6 is provided so as to be divided into multiple portions in the width direction of the steel strip, and is operated so as not to suck the steel strip carrier gas from the suction port 6 located at a position on the steel strip to be uncoated. .

In such a configuration, the uniform coating conditions will be described first.

When the discharge amount from the nozzle x (l / min), nozzle slit opening width s (mm), steel strip width direction application width w (mm), and the distance between the nozzle opening and the steel strip y (mm), steel Band running speed is 10
In the case of 0 m / min or less, by satisfying the following relationship, a meniscus can be formed stably and a uniform coating can be obtained.

y ・ s ・ w ・ 60 / x ≦ 30000 (μSEC) Under conditions other than this relationship, it becomes a random streak-like coating, so that a uniform coating film cannot be obtained and also the non-coating part can be controlled to a desired position. It was experimentally confirmed that it was impossible. That is, as the discharge amount x from the nozzle is larger, the nozzle slit opening width s is smaller, and the distance y between the nozzle opening and the steel strip is smaller, uniform coating can be easily obtained, but controlled partial coating is impossible. It indicates that there is.

Next, the above relationship does not hold when the running speed of the steel strip exceeds 100 m / min. This is because the atmosphere gas (air) carried by the steel strip is caught in the meniscus and causes the coating film to break. To prevent this, the transported atmospheric gas is sucked from the suction port 6. The required suction air volume varies greatly depending on the distance between the suction port and the steel strip, but when the nozzle slit face and the suction port face are aligned on the same plane, the suction air volume is 0.5 Nm ² / Hr or more.
Preferably, a suction air volume of 1 Nm ² / Hr or more is sufficient. In this manner, the uniform coating can be obtained by sucking the steel strip carrier gas from the suction port over the entire width direction of the steel strip. However, if a part of the suction port is closed and no suction is provided, the discharge corresponding to that is provided. It was found that the meniscus with the steel strip disappeared in the slit portion and the uncoated portion remained. Therefore, the suction port 6 is divided into multiple parts in the steel strip width direction, and the suction air volume from each of the divided suction ports can be controlled independently, so that the position of the uncoated portion in the steel strip width direction can be controlled. Was. As a result, the position of the uncoated portion on the steel strip can be instantaneously changed to a desired position, thereby eliminating the switching loss of a roll coater and at the same time enabling high-speed coating.

 Next, the present invention will be described with reference to examples.

(Embodiment) FIG. 1 shows an embodiment of the method of the present invention, in which a steel strip 5 has a surface cleaned by alkali degreasing or further pickling, and is run horizontally and vertically. An example of nozzle arrangement when traveling in the direction is also shown. The running of the steel strip 5 is stabilized by the support roll 4, and the resin coating nozzle 2 is installed on the opposite surface. The carrier gas suction port 6 is divided and installed on the same side of the steel strip 5 in the running direction of the steel strip 5 in the running direction. The nozzle 2 and the suction port 6 are brought close to the steel strip 5, and a commercially available metering pump is connected to the nozzle 2 to send the resin liquid 1 to be applied to the nozzle. A commercially available suction blower is connected to the suction port 6, and a flow rate adjusting valve 7 is provided so that the amount of suction air from each of the divided suction ports can be controlled.

An example in which a water-soluble resin is coated in such an apparatus configuration will be described. A steel strip 5 having a thickness of 0.2 mm and a width of 500 mm was used, and a resin coating nozzle 2 having a slit opening of 1 mm and a width of 490 mm was used. Similarly, a carrier gas suction port 6 having a gap of 5 mm and a width of 490 mm was used, and a partition wall having a thickness of 1 mm was provided at a pitch of 5 mm in the width direction of the steel strip. Steel strip running speed
Discharge rate of resin liquid at 100m / min 1 / min (wet thickness 20μ
In the case of m), the distance between the coating nozzle and the steel strip was 1 mm or less, and a uniform coating was obtained. 30 strip speed
For entrainment air If a 0m / min, 1Nm ³ from the carrier gas suction port so random coating breakage occurs
The conveying air of the steel strip was sucked at a suction air flow rate of / Hr to obtain a uniform coating. At this time, the distance between the suction port and the steel strip was 1 mm. This suction port is practically easy to operate if it is divided into multiple parts in the steel strip width direction and the suction air volume distribution in the steel strip width direction is changed according to the coating condition, but the uncoated part is fixed at a certain position on the steel strip. In order to keep the air flow, the suction air volume from the divided suction port corresponding to the desired position is set to zero. 5mm as an example
When the uncoated portion is left, the suction air volume from the 10 mm width of the divided suction port corresponding to the uncoated portion is set to zero. In this manner, an uncoated portion having an arbitrary width can be left at an arbitrary position on the steel strip, and the position and the width can be instantaneously switched by controlling the amount of suction air from the divided suction ports. The viscosity of the resin liquid used here is 50-500c
P. The uniform coating conditions studied are summarized in Table 1, and the non-coating conditions are summarized in Table 2.

Further, in the present invention, since the washing when changing the resin liquid can be easily performed, the resin type can be switched efficiently.

(Effects of the Invention) According to the present invention, a high-speed coating apparatus for a resin solution can be installed in a plating line, and a large quantity of final products can be obtained at low cost, and it is possible to efficiently respond to recent demand increases. In particular, by leaving the uncoated portion arbitrarily controlled, it is possible to efficiently supply a variety of materials in consideration of welding and joining corresponding to an arbitrary formed body of a customer.
Further, switching of the resin type is simple, and it is possible to immediately respond to various uses.

[Brief description of the drawings]

FIG. 1A shows an example of a coating method according to the present invention, and FIG. 1B is an enlarged plan view of the nozzle portion of FIG. 1A. 1: Resin liquid, 2: Coating nozzle, 3: Slit-shaped opening, 4: Support roll, 5: Steel strip, 6: Steel strip transfer air suction port, 7: Suction air flow control valve.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsuya Nishimura 1-1-1 Edamitsu, Yawatahigashi-ku, Kitakyushu-city, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (56) References JP-A-2-95473 (JP) , A) JP-A-52-82940 (JP, A)

Claims (1)

(57) [Claims] A nozzle is arranged on a coating surface of a running steel strip, an opening of the nozzle is brought very close to the steel strip, and a resin solution is supplied to the nozzle to collect a resin solution in the nozzle opening. Is formed, and coating is performed by a meniscus formed between the resin solution and the steel strip. In this method, a discharge amount x (liter / minute) from a nozzle, a nozzle slit opening width s (millimeter), and a coating in a steel strip width direction are applied. Width w (mm), distance y between nozzle opening and steel strip
(Millimeters), the following relational expression must be satisfied. Further, a gas suction port is arranged well in the steel strip running direction of the nozzle, and the suction port is divided into multiple parts in the width direction of the steel strip. A high-speed resin partial coating method characterized by sucking a band carrier gas. y ・ s ・ w ・ 60 / x ≦ 30000