JP2005111340A - Roll application method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique giving a good appearance of application to a substrate fed continuously at a high speed. <P>SOLUTION: A roll application method for an application solution comprises drawing the solution in a coater pan with a pick-up roll, adjusting the amount of the drawn solution with a metering roll, transferring to the solution to an applicator roll and contacting the applicator roll with a continuously running substrate to transferring the solution from the surface of the applicator roll to the surface of the substrate. The method is carried out at a peripheral speed Vp of the pick-up roll of ≥80 mpm in a Va/Vs peripheral speed ratio of ≤ 1.4, where Vs is the running speed of the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a roll coating method in which a coating process is continuously performed on a substrate using a roll coater.

  Conventionally, various coating films are formed on the surface of a steel sheet in order to impart performances such as corrosion resistance, workability, aesthetics, and insulation to a continuously running substrate such as a steel sheet. As this treatment method, a roll coater is generally used, and a two-roll coater using two rolls or a three-roll coater using three rolls is widely used. In particular, the three-roll coater is a mainstream coating method because it has excellent controllability of the coating film thickness and has a relatively beautiful surface appearance.

  The three-roll coater includes a pickup roll that draws up the coating liquid from a coater pan filled with the coating liquid, a metering roll that adjusts the amount of the coating liquid drawn up by the pickup roll, and the adjusted amount of the coating liquid from the pickup roll. It is comprised by the applicator roll transcribe | transferred to a steel plate. The rotation direction of each roll may be the reverse rotation that rotates in the opposite direction to the natural rotation that rotates in the same direction at the proximity point between the rolls or the contact point, but in general the reverse rotation is compared Since a smooth coating surface can be easily obtained, reverse rotation is often performed particularly between the applicator roll and the steel plate. The applicator roll uses a rubber roll in which rubber is lined on the steel roll so as not to damage the steel sheet surface.

  However, as a typical coating defect of a roll coater including a three-roll coater, a circumferential streak pattern called a roping is transferred to a steel sheet, resulting in uneven film thickness and appearance deterioration. Roping tends to occur more easily as the viscosity of the coating solution is higher and as the roll peripheral speed is higher. In particular, when the steel plate speed is increased, the peripheral speed of each roll is also increased, so that it is difficult to prevent the occurrence of roping.

As a method for reducing the occurrence of roping in high-speed application at a line speed of 200 mpm or more, Patent Document 1 discloses a method of applying the pick-up roll at a peripheral speed of 20 to 80 mpm and an applicator roll at a peripheral speed of 200 to 1000 mpm which is higher than the line speed. Is disclosed.
JP 10-309512 A (page 2)

  However, in the method disclosed in Patent Document 1, when the peripheral speed of the applicator roll is increased, the roping pitch on the applicator roll becomes finer and the roping is less noticeable on the steel plate. If the speed is increased too much, the flow of the coating liquid is disturbed at the position where the applicator roll and the steel sheet come into contact with each other, and the interface of the coating liquid locally vibrates in the width direction, resulting in a spotted pattern on the steel sheet. Therefore, increasing the peripheral speed of the applicator roll is an effective means for roping, but has a problem of creating a new factor of deterioration in the appearance of coating.

  Then, this invention aims at solving the said subject and providing the technique from which a favorable application | coating external appearance is obtained with respect to the base material continuous at high speed.

  In order to solve the above problems, the present invention pumps up the coating liquid in the coater pan with a pick-up roll, adjusts the amount of the pumped coating liquid with a metering roll, and then transfers the applicator roll to the applicator roll. In a roll coating method of a coating liquid in which a coating liquid on the surface of the applicator roll is transferred to the surface of the base material in contact with a continuously traveling base material, a peripheral speed Vp of the pickup roll is 80 mpm or more, and the base material The roll application method is characterized in that the peripheral speed ratio Va / Vs of the peripheral speed Va of the applicator roll with respect to the traveling speed Vs is 1.4 or less.

  Further, in this coating method, a plate-like blade is provided above the surface of the coater pan on the side where the liquid for picking up the coating liquid of the pick-up roll and close to the pick-up roll at a position where the pick-up roll and the metering roll are in contact or below the closest position. It is intended to provide a roll coating method that is characterized by installing.

  In the present invention, by applying a hydrodynamically stable flow of coating liquid at a location where roping and spotted pattern coating defects occur, it is possible to perform coating with no coating defects on a high-speed line regardless of the type of coating liquid. Processing becomes possible. According to the present invention, it is possible to improve productivity without causing quality deterioration due to coating defects.

  Embodiments of the present invention will be described below.

  In this invention, a coating liquid is apply | coated using the 3 roll coater on the single side | surface or both surfaces of the base material passed continuously. FIG. 1 is a diagram showing a configuration example of a main part of a roll coater used for carrying out the present invention. The roll coater transfers to the base material 1 the pickup roll 4 that pumps up the coating liquid 3 from the coater pan 2, the metering roll 5 that adjusts the amount of the coating liquid 3 on the pickup roll, and the adjusted coating liquid on the pickup roll. The applicator roll 6 is made up of.

  The rotation directions of the rolls are opposite to each other or between the applicator roll 6 and the substrate 1, and a blade 7 for scraping the coating liquid 3 is installed on the mitering roll 5. When the substrate 1 is a metal plate such as a steel plate, the applicator roll 6 uses a rubber roll in which rubber is lined on a steel roll. The base material 1 is coated with the coating liquid 3 while being wound around the backup roll 8.

  The coating liquid is applied as follows using the roll coater of FIG. That is, the coating liquid 3 in the coater pan 2 is pumped up by the pick-up roll 4, and the amount of the pumped coating liquid 3 is adjusted by the mitering roll 5, and then transferred to the applicator roll 6. The coating liquid is applied to the surface of the substrate 1 by contacting the traveling substrate 1 and transferring the coating liquid 3 on the surface of the applicator roll 6 to the surface of the substrate. The base material 1 with the coating liquid applied to the surface is then passed through a heating facility or a drying facility (not shown) and dried by heating to form a required coating film on the surface of the base material 1. The coating liquid 3 adhering to the surface of the mitering roll 5 is scraped off by a blade 7 arranged with one end pressed against the surface of the mitering roll 5 and returns to the coater pan 2.

  In such a roll coater, the conditions for the occurrence of roping mainly depend on the peripheral speed of each roll, the gap between each roll, or the pressing pressure, and the physical properties of the coating liquid (viscosity, surface tension). Naturally, since the peripheral speed of each roll is increased, roping tends to occur.

  Although roping may occur between the metering roll 5 and the pickup roll 4 and between the pickup roll 4 and the applicator roll 6, it always occurs in the latter in high-speed coating. In addition, when roping occurs in the latter, the roping generated in the former is canceled, so it is only necessary to pay attention to between the pickup roll 4 and the applicator roll 6.

  As a result of various experiments, as the peripheral speed of the pick-up roll 4 is increased, the roping pitch on the applicator roll 6 becomes smaller, and when the pick-up roll peripheral speed is 80 mpm or more, roping with a very fine pitch is performed. was gotten. If the pitch of roping is reduced, uneven coating may become inconspicuous, but the leveling effect will increase between application and drying, and uneven coating will become more inconspicuous after drying by heating, improving the appearance after drying. To do.

  Furthermore, if the peripheral speed of the applicator roll is suppressed to 1.4 times or less of the speed of the substrate 1 (also referred to as the line speed), the interface of the coating liquid at the position where the applicator roll and the steel plate are in contact with each other is vibrated. No spotted pattern was generated.

  The pick-up roll peripheral speed is desirably in the range of 80 to 150 mpm. This is because when the peripheral speed of the pickup roll is 150 mpm or more, scattering of the coating liquid becomes severe and workability is deteriorated, and roping is prevented in this peripheral speed range and a good appearance is obtained. The applicator roll peripheral speed is preferably in the range of 0.8 to 1.4 with respect to the line speed. When the peripheral speed of the applicator roll is less than 0.8 with respect to the line speed, it becomes easy to entrain the air accompanying the trip of the applicator roll 6 and the base material 1. This is because the pattern is likely to occur.

  In the above-described method, when the peripheral speed of the pick-up roll is increased, depending on the physical properties of the coating liquid 3, the coating liquid 3 may be scattered or a large amount of the coating liquid 3 on the mitering roll 5 scraped off by the blade 7. When returning to the coater pan 2, air is entrained and a large amount of foam is generated, and the pick-up roll 4 draws up the coating liquid entraining the foam, resulting in a coating defect.

  The above-mentioned problems can be prevented by suppressing the lifting amount of the coating liquid 3 due to the increase in the peripheral speed of the pickup roll. In order to suppress the lifting amount of the coating liquid 3 due to the increase in the peripheral speed of the pick-up roll, as shown in FIG. 2, the pick-up roll 4 and the mita are disposed above the liquid surface of the coater pan 2 on the pick-up roll 4 side. It is preferable to install a plate-like blade 9 with one end thereof close to the pickup roll 4 below the contact position with the ring roll 5 or the closest approach position.

  The blade 9 is not brought into contact with the pickup roll 4, and a gap is provided so as to scrape off a certain amount of the coating liquid lifted by the pickup roll 4. For this purpose, the clearance between the plate-like blade 9 and the pickup roll 4 is preferably about 0.1 to 0.5 mm. If it is less than 0.1 mm, the uniformity of the gap cannot be secured in the roll width direction, and the coating liquid on the pickup roll 4 after scraping with the blade 9 becomes non-uniform in the roll width direction. If it exceeds 0.5 mm, the effect of suppressing the lifting amount of the coating liquid of the pick-up roll will be insufficient, resulting in scattering of the coating liquid and generation of a large amount of bubbles.

  It is possible to suppress the lifting amount of the coating liquid 3 by increasing the peripheral speed of the pick-up roll, but it is possible to arrange the roll close to the pick-up roll 4, but when using the roll, roping occurs after scraping with the roll, The coating liquid on the pickup roll 4 becomes non-uniform in the roll width direction. The plate-like blade 9 has the advantages that the above-mentioned problems are not caused and the equipment is inexpensive.

  The position of the blade 9 in the height direction is preferably closer to the liquid surface of the coating liquid 3 in the coater pan 2. This is because the effect of preventing entrainment of bubbles when the coating liquid 3 scraped off by the blade 9 returns into the coater pan 2 is more excellent.

  Since the amount of lifting of the coating liquid 3 by the pickup roll 4 can be suppressed by installing the blade 9 close to the pickup roll as described above, the coating liquid 3 does not scatter even when the pickup roll 4 is operated at high speed. Since a small amount of the coating liquid 3 is scraped off by the blade 7 on the mitering roll 5, the generation of bubbles can be suppressed even with respect to the coating liquid 3 having good foaming properties.

  In the above-described coating method, as shown in FIGS. 1 and 2, the coating liquid is applied to the base material 1 that is passed through in the vertical direction with the base material 1 wound around the backup roll 8. In the invention, a roll coater may be disposed on both sides of the base material 1 and the coating solution may be simultaneously applied to both surfaces of the base material 1 without being wound around the backup roll. In addition, the plate-passing direction of the substrate 1 may be either a horizontal pass or a vertical pass.

  The present invention will be described in detail with reference to the following examples and comparative examples.

  A cold-rolled steel strip having a plate thickness of 0.5 mm and a plate width of 1200 mm is continuously coated under the coating conditions shown in Table 1 using the coating apparatus shown in FIG. Evaluation was performed. In the coating apparatus of FIG. 1, the material of each roll is a rubber roll in which an applicator roll 6 lines a rubber to a steel roll, a pickup roll 4 and a metering roll 5 are metal rolls, and the roll diameter of each roll is the same as that of the applicator roll 6. The pickup roll 4 is 300 mmφ, and the mitering roll 5 is 200 mmφ. The gap between the pick-up roll 4 and the mitering roll 5 was adjusted in the range of 50 to 150 μm so that the coating film thickness was constant. Similarly, the peripheral speed of the mitering roll 5 was adjusted in the range of 10 to 120 mpm so that the coating film thickness was constant. The coating solution used was one having a viscosity of 1 cp and a surface tension of 40 dyn / cm at a liquid temperature of 20 ° C. The appearance after the application was evaluated by visual observation under a sufficiently bright fluorescent lamp to evaluate the presence or absence of roping and spotted patterns. Moreover, the appearance in which both roping and the spotted pattern did not occur was evaluated as good in appearance, and the appearance in which at least one of them occurred was evaluated as poor in appearance. The evaluation results of the appearance after coating are shown in Table 1.

  As shown in Table 1, in the method of the present invention, a good appearance was obtained even when the speed of the substrate (line speed) was increased, whereas in the conventional method, the condition that the pick-up roll peripheral speed was less than 80 mpm When the peripheral speed of the applicator roll exceeded 1.4 with respect to the speed of the base material, roping occurred in the former, and a coating defect occurred due to a spotted pattern in the latter.

  Moreover, the Example using the coating device shown in FIG. 2 is shown. The same roll material and roll diameter as in Example 1 were used. The same cold-rolled steel sheet strip as in Example 1 was used, and the coating conditions were those described in Table 2. Although the viscosity and surface tension of the coating solution were the same as in Example 1, a coating solution that was easier to foam than the coating solution used in Example 1 was used. The gap between the blade 9 and the pickup roll 4 that suppresses the amount of coating liquid lifted by the pickup roll 4 was 0.3 mm.

  The presence or absence of scattering of the coating liquid from the pick-up roll 4 and the degree of bubble generation on the coater pan 2 liquid surface were observed. Further, in the same manner as in Example 1, the appearance of the coating was observed, and the presence / absence of roping and spotted pattern was evaluated, and no coating defects due to roping, spotted pattern, or bubble mixing occurred. Appearance was good, and the appearance of any one or more coating defects was evaluated as poor appearance. The observation results are shown in Table 2.

  As shown in Table 2, in the method of the present invention, even when the peripheral speed of the pick-up roll 4 was increased, the coating liquid was not scattered, the generation of bubbles was suppressed, and workability was not deteriorated. Further, no roping or spotted pattern was generated, and there was no deterioration of the coating appearance in which bubbles were mixed. On the other hand, in the case of the comparative method in which the blade 9 is not installed, not only the appearance of the coating is deteriorated due to the generation of a large amount of bubbles, but also the workability is deteriorated due to the overflow of bubbles from the coater pan 2 and the continuous operation for a long time. There was a problem that became difficult. Therefore, it can operate stably on the conditions which can make application | coating external appearance favorable by applying this invention also to the coating liquid with good foamability.

  In Examples 1 and 2, a cold-rolled steel sheet was used as the base material. However, the present invention is not particularly limited to a steel sheet, and can be applied to other metal plates such as aluminum, paper, and films.

  INDUSTRIAL APPLICABILITY The present invention can be used as a method for obtaining a good coating appearance when a coating liquid is continuously applied to a metal plate such as a steel plate or aluminum, or a substrate such as paper or film, particularly at a high speed.

It is a side view which shows the principal part structural example of the coating device used for implementation of this invention. It is a side view which shows the principal part structural example of another coating device used for implementation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Coater pan 3 Coating liquid 4 Pickup roll 5 Mitering roll 6 Applicator roll 7 Blade 8 Backup roll 9 Blade (plate-shaped blade)

Claims (2)

The coating liquid in the coater pan is pumped up with a pick-up roll, and after adjusting the liquid volume of the pumped-up coating liquid with a mitering roll, it is transferred to the applicator roll, and the applicator roll is brought into contact with the substrate that runs continuously, In the roll coating method of the coating liquid for transferring the coating liquid on the surface of the applicator roll to the surface of the base material, the peripheral speed Va of the applicator roll with respect to the traveling speed Vs of the base material is 80 mpm or more. The roll coating method is characterized in that the peripheral speed ratio Va / Vs is 1.4 or less. It is characterized in that a plate-like blade is installed close to the pickup roll above the surface of the coater pan on the side where the liquid for picking up the coating liquid of the pickup roll is above and below the contact position between the pickup roll and the metering roll or the closest approach position. The roll coating method according to claim 1.

Images