JP2005342643A - Roll coating method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll coating method and apparatus giving a good coated appearance to a substrate fed continuously at a high speed. <P>SOLUTION: In the roll coating method in which coating liquid is applied to the substrate running continuously by a roll brought into contact with or close to the substrate, a vibrator is disposed in a liquid bank between an applicator roll for applying the coating liquid and the substrate and the vibrator is vibrated, thereby applying the vibration to the coating liquid in the liquid bank. A wire is used as the vibrator. The number of vibration of the vibrator is to be not less than the value obtained by the expression: line speed LS(m/s)×1,000(Hz). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roll coating method and a roll coating apparatus that perform a coating process continuously on a substrate using a roll coater.

  Conventionally, various coating films are formed on a steel sheet surface in order to impart performances such as corrosion resistance, workability, aesthetics, and insulation to a continuously running base material, 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 film surface is easily obtained, reverse rotation is often performed particularly between the applicator roll and the steel plate. The applicator roll uses a rubber lining 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 liquid 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.

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, an object of this invention is to provide the roll coating method and roll coating device which solve the said subject and can obtain a favorable coating external appearance with respect to the continuous base material at high speed.

  Means of the present invention for solving the above problems are as follows.

  1st invention is a roll coating method which apply | coats coating liquid with the roll which contacted or adjoined the base material which drive | works continuously, and arrange | positions a vibrating body in the liquid reservoir part between the applicator roll which apply | coats coating liquid, and a base material. Then, the roll applying method is characterized in that the vibrating body is vibrated to apply vibration to the coating liquid in the liquid reservoir.

  A second invention is a roll coating method according to the first invention, wherein the vibrator is a wire.

  A third invention is the roll coating method according to the first or second invention, wherein the vibration body has a line frequency (m / s) LS × 1000 [Hz] or more.

  4th invention is a roll coating apparatus which apply | coats a coating liquid with the roll which contacted or adjoined the base material which drive | works continuously, This liquid reservoir is in the liquid reservoir part between the applicator roll which apply | coats a coating liquid, and a base material. A roll coating apparatus comprising a vibrating body that imparts vibration to a coating liquid of a portion.

  According to a fifth invention, in the fourth invention, the vibrator is a wire arranged with tension in the width direction of the base material, and provided with vibration imparting devices that impart vibration to the wire at both ends of the wire. Is a roll coating apparatus characterized by

  In the present invention, a vibrating body is disposed in a liquid pool portion between a roll and a steel plate at a location where a coating defect such as roping or a spotted pattern is generated, and the vibrating body is vibrated to forcibly vibrate the liquid pool portion. By providing the above, it becomes possible to perform coating processing without coating defects on a high-speed line regardless of the type of coating solution. 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.

  The following embodiment demonstrates the case where a coating liquid is apply | coated to the single side | surface of the base material passed continuously using a 3 roll coater. FIG. 1 is a side view showing a configuration example of a main part of a roll coater according to an embodiment of the present invention, and FIG. 2 is a plan view of the roll coater of FIG. In this apparatus, the vibrating body disposed in the liquid reservoir is a wire. FIG. 3 is a schematic diagram illustrating a configuration example of a vibration applying device that applies vibration to the wire, and illustrates a cross section taken along the line AA of FIG. 2.

  The roll coater is based on the pickup roll 4 that pumps 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 4, and the adjusted coating liquid 3 on the pickup roll 4. An applicator roll 6 and an applicator roll 6 to be transferred to 1 are provided, and a wire rod 9 is further arranged to contact the liquid reservoir portion of the substrate 1 and vibrate the liquid reservoir portion.

  Both ends of the wire 9 are held in a tensioned state by a fixing device 11 that fixes the wire 9 in the longitudinal direction of the wire 9, and the vicinity of the end of the wire 9 has a vibrator that applies vibration to the wire 9. The vibration device 10 is pressed from below. The vibrator of the vibration device 10 has a variable frequency, and when the vibrator is vibrated, the wire 9 vibrates accordingly. Since the size of the liquid reservoir portion changes depending on the coating film thickness, the conveyance speed of the base material 1, the peripheral speed of the applicator roll, etc., the vibration device 10 and the fixing device 11 are arranged in the vertical and horizontal directions of the wire 9. It is attached to the position adjusting device 12 to be adjusted. Since the liquid reservoir between the applicator roll 6 and the substrate 1 is small, it is necessary to be able to adjust the position of the wire in order to bring the wire into contact with the liquid reservoir with high accuracy. By providing the position adjusting device 12, the wire 9 can be brought into contact with the liquid reservoir between the applicator roll 6 and the substrate 1 with high accuracy.

  As the vibrator, for example, an ultrasonic vibrator or the like can be used. Alternatively, the vibration may be generated by using a vibration generating means such as a speaker, and a wire may be installed in the vibration device to vibrate. The vibration direction of the wire 9 may be any of a substrate running direction, a substrate width direction, a direction perpendicular to the substrate surface, and a direction oblique to the above directions. The vibration device 10 may press the top and bottom of the wire 9 simultaneously.

  In this apparatus, the wire is brought into contact with the liquid reservoir to apply vibration. Here, the contact of the wire with the liquid reservoir means that when the wire is vibrated, each part in the longitudinal direction of the wire is not always outside the liquid reservoir, in other words, at least part of the vibration cycle. In this case, it is sufficient that the wire is in contact with the liquid reservoir. Paying attention to a certain part in the longitudinal direction of the wire, the part may vibrate repeatedly during the vibration cycle between the state inside the liquid reservoir and the state outside the liquid reservoir, or always vibrates inside the liquid reservoir. Also good. FIG. 4 is a diagram illustrating the vibration state of the wire when vertical vibration is applied to the wire. In FIG. 4, A is a liquid reservoir, 9 is a wire, and an arrow in the vertical direction of the wire 9 is the amplitude of the wire 9. From the viewpoint of ensuring that the vibration node of the wire 9 is present in the liquid reservoir when the wire 9 is vibrated, the wire 9 is in the liquid reservoir or is in contact with the liquid reservoir without applying vibration. It is preferable to arrange in a position. The amplitude when vibrating the wire is preferably less than 1 mm in order to disperse the unevenness of the liquid film due to coating unevenness such as roping when the coating liquid is applied to the substrate.

  The arrows in FIG. 1 indicate the rotation direction of the roll or the traveling direction of the substrate. The rotation directions of the rolls are opposite to each other or between the applicator roll 4 and the substrate 1, and a blade 7 that scrapes 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 lining 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 solution is applied as follows using the roll coater of FIGS. 1 and 2. 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 3 is applied to the surface of the base material 1 by contacting the traveling base material 1 and transferring the coating liquid 3 on the surface of the applicator roll 6 to the surface of the base material. The base material 1 having the coating liquid 3 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). Since the peripheral speed of each roll is inevitably increased, it is difficult to avoid the occurrence of roping.

  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 that occurs in the former is canceled, so it is only necessary to pay attention to between the pickup roll 4 and the applicator roll 6.

  The fact that the frequency of the wire is defined as the line speed (m / s) LS × 1000 [Hz] or more is based on the following knowledge. As a result of examination by various experiments, the following became clear. When the peripheral speed of the pickup roll 4 is in the range of 20 to 150 mpm, roping occurs between the pickup roll 4 and the applicator roll 6, and when the applicator roll 6 is brought into contact with the substrate 1, streaks are transferred to the steel plate. Is done. By measuring the roping pitch at each peripheral speed condition and the frequency at the liquid reservoir with a high-speed camera, and applying a frequency of 1000 times or more to the line speed (LS) [m / s] to the wire In addition, the flow of the liquid reservoir between the applicator roll 6 and the base material 1 can be stabilized and coating unevenness can be eliminated.

  The pick-up roll peripheral speed is desirably in the range of 150 mpm or less. This is because when the peripheral speed of the pickup roll is 150 mpm or more, the coating liquid scatters and the workability deteriorates. In addition, it is desirable that the applicator roll peripheral speed is in the range of 0.8 to 1.4 with respect to the line speed (traveling speed of the substrate 1). When the peripheral speed of the applicator roll is less than 0.8 with respect to the line speed, air accompanying the trip of the applicator roll 6 and the base material 1 is entrained, and stripe-like unevenness is likely to occur. If the peripheral speed of the applicator roll exceeds 1.4 with respect to the line speed, the liquid reservoir between the substrate 1 and the applicator roll 6 becomes minute, and it becomes difficult to install the wire 9.

  When the pitch of the unevenness generated at the liquid reservoir portion of the applicator roll 6 and the base material 1 is less than 1 mm, the uneven application after the coating liquid is dried is less noticeable. When the frequency applied to the wire 9 is increased, it is possible to reduce the pitch of the coating unevenness (film thickness variation) in the substrate width direction that occurs in the liquid reservoir of the applicator roll 6 and the substrate 1. The frequency (Hz) applied to the wire 9 is 1000 times or more the conveyance speed (m / s) of the base material 1, so that coating unevenness occurs in the applicator roll 6 and the liquid reservoir portion of the base material 1. The pitch of (film thickness variation) can be set to less than 1 mm, coating unevenness after drying the coating liquid becomes less noticeable, and a good appearance can be obtained. On the other hand, when the frequency (Hz) applied to the wire 9 is less than 1000 times the conveyance speed (m / s) of the substrate 1, the pitch of the coating unevenness (film thickness variation) becomes 1 mm or more, and the coating is performed. The coating unevenness after drying the liquid becomes conspicuous.

  In addition, in this apparatus, since a wire is directly arranged in a nonuniformity generation part and a vibration is given and application nonuniformity is prevented, there exists an effect that the steel plate with the very favorable external appearance after application | coating is obtained. The material of the wire is not particularly limited, but a metal wire is preferable from the viewpoint of durability. The diameter of the wire is preferably 200 μmφ or less in order to allow contact with the liquid reservoir between the applicator roll and the steel plate.

  In this device, the vibration applying device is arranged at both ends of the wire arranged with tension in the substrate width direction to apply vibration to the wire, but as another form of applying vibration to the wire, the upper part of the wire In addition, a wire or a square may be placed in contact with the wire in parallel with the wire, and the wire may be vibrated by applying vibration to the member.

  In the above-described coating method, as shown in FIG. 1, the coating liquid 3 is applied to the base material 1 that is passed through in the vertical direction while the base material 1 is wound around the backup roll 8. A roll coater may be disposed on both sides of the substrate, and the coating solution may be simultaneously applied to both sides of the substrate 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.

  Although the said embodiment described the coating system by a 3 roll system, in this invention, it is not limited to a 3 roll system. For both 1-roll and 2-roll systems, unevenness in coating on the steel sheet is eliminated by installing a wire in the liquid reservoir between the applicator roll and the substrate and applying vibration to the wire in the same manner as described above. The FIG. 5 and FIG. 6 show one configuration example of the two-roll and one-roll embodiments, respectively.

  The roll coater of FIG. 5 includes a pickup roll 4 that pumps up the coating liquid 3 from the coater pan 2, a metering roll 5 that adjusts the amount of the coating liquid 3 on the pickup roll 4, and the adjusted coating liquid 3 on the pickup roll 4. The applicator roll 6 and the applicator roll 6 are transferred to the base material 1, and the wire rod 9 is arranged to contact the liquid reservoir portion of the base material 1 and vibrate the liquid reservoir portion. The arrows in the figure indicate the rotation direction of the roll or the traveling direction of the substrate. When the coating liquid 3 pumped up by the pickup roll 4 is transferred to the applicator roll 6, the amount of the liquid is adjusted. The coating liquid 3 transferred to the applicator roll is applied to the substrate 1.

  The roll coater of FIG. 6 includes an applicator roll 6 that applies the coating liquid 3 to the substrate 1 and a coating liquid supply nozzle 13 that supplies the coating liquid 3 to the applicator roll 6. A wire rod 9 is disposed that is brought into contact with the pool portion and vibrates the pool portion. The arrows in the figure indicate the rotation direction of the roll or the traveling direction of the substrate. The amount of the coating liquid 3 applied to the substrate 1 is adjusted by the amount of liquid supplied from the coating liquid supply nozzle 13 to the applicator roll 6.

  Examples of the present invention will be described below.

  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 lining 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 an applicator roll. 6 and the pickup roll 4 are 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 traveling direction of the steel plate 1 and the rotation direction of each roll are directions indicated by arrows in FIG.

  A wire rod 9 having a diameter of 100 μm was installed in a liquid reservoir between the applicator roll 6 and the steel plate 1, and vibrators were attached to both ends of the wire rod 9 to vibrate in a vertical direction in a tensioned state. The amplitude of the wire at this time was 500 μm. The frequency at which the wire 9 is vibrated was in the range of 200 to 5000 Hz depending on the peripheral speed condition. 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 coating was evaluated by visual observation under a sufficiently bright fluorescent lamp and observation with a high-speed camera 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 base material (line speed) was increased, whereas in the conventional method, the condition where the pick-up roll was low or the applicator roll When the peripheral speed 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.

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

  The method of the present invention is used as a method for obtaining a good coating appearance when coating a coating solution continuously, particularly at a high speed, on a substrate such as a steel plate, a metal plate such as aluminum, paper or a film. Can do.

  The apparatus of the present invention is used as an apparatus for obtaining a good coating appearance when applying a coating liquid continuously to a substrate such as a steel plate, a metal plate such as aluminum, paper, or a film, particularly at a high speed. Can do.

It is a side view showing an example of important section composition of a 3 roll coater concerning an embodiment of the invention. It is a top view which shows the principal part structural example of the 3 roll coater which concerns on embodiment of this invention. In the roll coating apparatus which concerns on embodiment of this invention, it is the schematic explaining the structure of the vibration provision apparatus which provides a vibration to a wire. It is an expansion schematic diagram of the liquid reservoir part explaining the vibration state (amplitude) of the wire in the liquid reservoir part between an applicator roll and a base material. It is a side view which shows the principal part structural example of the 2 roll coater which concerns on embodiment of this invention. It is a side view showing an example of important section composition of a 1 roll coater concerning an embodiment of the 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 Wire material 10 Vibrating device 11 Wire material fixing device 12 Wire material position adjustment device 13 Coating liquid supply nozzle A Liquid accumulation part

Claims (5)

In a roll coating method in which a coating liquid is applied with a roll that is in contact with or close to a substrate that is continuously running, a vibrating body is disposed in a liquid reservoir between the applicator roll that coats the coating liquid and the substrate, and the vibrating body Is applied to the coating liquid in the liquid reservoir portion to cause a vibration. The roll coating method according to claim 1, wherein the vibrating body is a wire. 3. The roll coating method according to claim 1, wherein a frequency of the vibrating body is a line speed (m / s) LS × 1000 [Hz] or more. In a roll coating apparatus that coats a coating liquid with a roll that is in contact with or in proximity to a continuously running substrate, the coating liquid is applied to the liquid reservoir between the applicator roll that coats the coating liquid and the substrate. A roll coating apparatus comprising a vibrating body that imparts vibration. The roll according to claim 4, wherein the vibrating body is a wire arranged with tension in the width direction of the base material, and includes a vibration applying device that applies vibration to the wire at both ends of the wire. Coating device.

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