JP2011206687A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus for obtaining a uniform coating film by stably sending a coating solution to a liquid receiving pan in a case that a region where the shearing speed of coating solution is low is coated with the coating solution having high viscosity by a gravure coater.SOLUTION: The coating apparatus includes the circular arc-shaped solution receiving pan installed for the purpose of transferring the coating solution to the gravure roll and concentrically arranged with respect to the gravure roll and a solution injection port for injecting the coating solution to the solution receiving pan from a position present in the downstream side of the rotating direction of the gravure roll and higher than the liquid level of the coating solution in the solution receiving pan.

Description

  The present invention relates to a coating apparatus for stably feeding a coating liquid and obtaining a uniform coating film when a high-viscosity coating liquid is applied with a gravure coater.

  The gravure coating method is currently widely used as a coating method for various coating solutions. This coating method can be easily realized by placing the coating liquid on a gravure roll, scraping off the excess coating liquid with a doctor blade, and transferring the ink in the concave portion of the gravure roll to the substrate. Therefore, the applicable range of the coating liquid physical properties is wider than other coating methods.

  However, since the coating liquid is placed on the gravure roll, the roll is immersed while the coating liquid is placed in the liquid receiving pan, so the management of the coating liquid in the liquid receiving pan is possible. It ’s hard to get along. For example, since the solvent in the coating liquid evaporates in the liquid receiving pan that is open to the atmosphere, the viscosity rises in the liquid receiving pan, causing variations in the coating film on the substrate, and quality control of the coated product. It becomes an upper problem.

  In general, the above problem is that the state of the coating liquid in the liquid receiving pan is made constant by circulating the coating liquid in the liquid receiving pan to the liquid injection side again while extracting a predetermined amount from the waste liquid port. To avoid. However, in order to circulate, it is essential that the viscosity is low to some extent, and in the case of a high viscosity liquid, it becomes difficult. In particular, since the shear force is not applied in the state in the liquid receiving pan, the coating liquid having a high viscosity in the region where the shear rate is low is difficult to handle because a staying portion is formed in the liquid receiving pan.

  From the viewpoint of quality control of the coating liquid, it is effective to make the flow of the coating liquid in one direction with as few open parts as possible. Although the coating method is different from the gravure method, die coating is a good example. However, in die coating, there is no open part and the flow of the coating liquid can be unidirectional. However, when coating with a coating liquid with high viscosity, there is a variation in the coating amount in the width direction of the substrate. Which is undesirable. Further, as in Patent Document 1, a method has been proposed in which a fountain-type nozzle is used to directly discharge a coating liquid onto a gravure roll.

  However, in this method, until the coating liquid is placed on the gravure roll, it is preferable that there is no open portion and it is unidirectional. However, in order to discharge the liquid from the nozzle and place it on the gravure roll, the gap between the roll and the nozzle is preferred. Need to be set. In Patent Document 1, although the doctor blade and the nozzle are integrated, it can be scraped off by the doctor blade and the variation in the coating amount can be suppressed. The higher the coating liquid, the more difficult it becomes.

Japanese Patent Laid-Open No. 5-128512

  When applying a coating liquid with high viscosity in a region where the shear rate of the coating liquid is low, using a gravure coater, the coating liquid is stably supplied to the liquid receiving pan to obtain a uniform coating film. It is an object to provide an apparatus.

  The inventor has found that the above problem can be solved by specifying the method of supplying the coating liquid to the liquid receiving pan and the state of the coating liquid in the liquid receiving pan, and to complete the present invention. It came.

    The invention described in claim 1 includes a gravure roll, an arc-shaped liquid receiving pan disposed concentrically with the gravure roll installed to transfer the coating liquid to the gravure roll, and downstream of the rotation direction of the gravure roll. And a liquid injection port for injecting the coating liquid into the liquid receiving pan from a position higher than the liquid level of the coating liquid in the liquid receiving pan.

The invention according to claim 2 is a gravure roll, a liquid receiving pan disposed on the gravure roll, and at a position higher than the liquid level of the coating liquid in the liquid receiving pan on the downstream side in the rotation direction of the gravure roll. The liquid receiving pan has a liquid injection port for injecting the coating liquid into the liquid receiving pan, the distance between the bottom of the gravure roll upstream in the rotation direction of the gravure roll and the roll is less than 10 mm, and the rotation of the gravure roll The coating apparatus is characterized in that the distance between the bottom portion on the downstream side in the direction and the roll is 10 mm or more and 100 mm or less.
The invention according to claim 3 is characterized in that the liquid injection port is installed at a height of 20 mm or more and 100 mm or less in the vertical direction from the liquid surface of the coating liquid. Coating equipment.

  The invention according to claim 4 is the manufacturing apparatus according to any one of claims 1 to 3, wherein the liquid injection port has a fountain-type nozzle shape.

  The invention according to claim 5 is characterized in that a coating liquid having a shear viscosity of 1000 [mPa · s] or more and 20000 [mPa · s] or less at a shear rate of 1 [1 / s] is used. The coating apparatus according to any one of claims 1 to 4.

  Since the present invention is configured as described above, variations in the coating amount can be suppressed even with a coating solution having a high viscosity in a region where the shear rate is low. While controlling the physical properties of the coating liquid, it can be applied with a gravure coater.

It is explanatory drawing which shows an example of a general gravure coater. It is explanatory drawing which shows an example of the gravure coating part by this invention. It is explanatory drawing which shows an example of the liquid receiving pan of the gravure coating part by this invention.

  Hereinafter, the present invention will be described in more detail. FIG. 1 shows a schematic diagram of a general gravure coater.

  When the coating liquid is supplied to the liquid receiving pan 13, it is lifted up by the gravure roll 12, measured by the doctor blade 20, and then transferred to the substrate. At this time, the one in which the gravure roll 12 advances in the same direction with respect to the substrate running direction is referred to as a direct method, and the one in the reverse direction is referred to as a reverse method. Moreover, although there exist what is installed in the position where the backup roll 11 presses with respect to the gravure roll 12, and the kiss system without the backup roll 11, etc., this invention is effective in any method.

  The present invention defines a method of supplying the coating liquid to the liquid receiving pan, and the effect is not limited by the shape, material, installation position and angle of the doctor blade. The same applies to the gravure roll, and it is not limited to the engraved pattern, roll diameter, material, and the like.

  The supply of the coating liquid to the liquid receiving pan 13 is generally carried out by a liquid feed pump 16. In the coating liquid having a high viscosity in the low shear rate region used in the present invention, the fluidity of the coating liquid is only in the vicinity of the coating liquid supply port and the rotating gravure roll in the liquid receiving pan. In other places, the coating liquid stays.

  Therefore, in the present invention, as shown in FIG. 2, an arc-shaped liquid receiving pan 21 arranged concentrically with the gravure roll 12 and a fountain-type nozzle 23 for supplying a coating liquid to the liquid receiving pan 21 are formed. In the downstream of the rotation direction of the gravure roll, it is installed at a position higher than the liquid surface of the coating liquid.

  The upstream side in the rotation direction of the gravure roll refers to the side where the gravure roll that has applied the coating liquid to the substrate 10 comes into contact with the coating liquid in the liquid receiving pan again, and the downstream side is The gravure roll in contact with the coating liquid in the liquid receiving pan refers to the side toward the substrate.

  Here, the arc-shaped liquid receiving pan arranged concentrically with the gravure roll is a structure in which the liquid receiving pan has an arc-shaped bottom surface along the gravure roll as shown in FIG. This means that the center of the arc is arranged so as to coincide with the center of the gravure roll.

  For coating liquids with high viscosity in the region where the shear rate is low, the fluidity of the coating liquid in the vicinity of the liquid surface immediately before scraping off the coating liquid scraped by the rotation of the gravure roll with a doctor blade is particularly important. If there is variation in the fluidity of the coating liquid here, the scraping amount becomes non-uniform in the width direction, and variation in the coating amount cannot be suppressed, and there is a risk of causing unevenness in the coating film.

  Therefore, in the present invention, the coating liquid is injected from the fountain nozzle from the downstream side in the rotation direction of the gravure roll and from a position higher than the level of the coating liquid. The gravure roll and the flow of coating liquid falling from a position higher than the liquid level cause the gravure roll and the coating liquid in the reverse direction to rotate in the liquid receiving pan downstream of the gravure roll rotation direction. The flow 25 is generated, and uniform fluidity can be provided in the width direction.

  Here, as shown in FIG. 3, the liquid injection port 24 of the fountain-type nozzle 23 is desirably located at a position 26 of 20 mm or more and 100 mm or less in the vertical direction from the coating liquid surface. When it is less than 20 mm, there is a possibility that sufficient fluidity of the liquid cannot be obtained in the liquid receiving pan. In addition, when it is higher than 100 mm, bubbles are generated when the falling coating liquid and the coating liquid in the liquid receiving pan come into contact with each other, and there is a risk that the coating surface may be uneven due to the foam. is there.

  In the liquid receiving pan 21, the distance 27 between the bottom of the gravure roll in the rotation direction and the roll is less than 10 mm, and the distance between the bottom of the gravure roll in the rotation direction and the roll. 28 is preferably 10 mm or more and 100 mm or less.

  When the distance between the bottom of the gravure roll upstream in the rotation direction and the gravure roll is less than 10 mm, the fluidity of the liquid is obtained by the shearing force generated by the rotation of the gravure roll, and the staying portion can be made almost zero.

  However, when the entire arc of the liquid receiving pan is set to be less than 10 mm, the buffer effect due to the installation of the liquid receiving pan does not appear.

  Therefore, by increasing the distance between the bottom of the gravure roll in the rotation direction and the roll to 10 mm or more and 100 mm or less, the staying portion of the coating liquid can be reduced while leaving the buffer effect.

  Further, if the distance between the bottom of the gravure roll on the downstream side in the rotation direction and the roll is increased by 100 mm or more, there is a possibility that the staying portion may increase, which is not preferable.

  The slit of the fountain nozzle 23 should be set within a range that does not affect the pressure resistance of the pump, and generally takes a value between 100 μm and 1 mm. The opening width of the nozzle is preferably almost equal to the coating width of the gravure plate (the width on which the pattern of the plate is engraved), but it is not necessary to be completely equal. However, if the wide area is about 100 mm, there is no problem.

  It is desirable to supply the coating liquid to the liquid receiving pan as much as possible, but it is recommended to install a pan to receive the overflowing coating liquid and discharge it appropriately. It is also possible to make heavy bread. However, at this time, from the viewpoint of physical property management of the coating liquid, a step of discarding the coating liquid without returning it to the original supply system may be provided. To that end, supply should be managed.

  The end of the liquid receiving pan is made longer than the roll surface length of the gravure roll, and the width is within 50 mm. If the length is longer than that, a retention portion tends to be formed at the end portion, and the problem with the retention increases as the coating liquid has a higher viscosity in the region where the shear rate is low as used in the present invention. However, if the gravure roll and the end of the liquid receiving pan come into contact with each other, a foreign matter failure may occur. Therefore, the length needs to be 5 mm or longer than the roll surface length.

  The material constituting the liquid receiving pan is generally a metal such as stainless steel or aluminum, and the accuracy of the shape is not so much required. Therefore, it is desirable to manufacture with a light material. It is also possible to coat the inner surface with a fluororesin in consideration of detergency.

  It is preferable to connect the fountain-type nozzle and the liquid receiving pan by welding so as to continuously supply a stable coating liquid so as not to generate bubbles. It is also possible to separate the fountain nozzle and the liquid receiving pan when considering workability. In that case, a packing made of resin is provided at the tip of the fountain-type sill, and the coating liquid leaks from the connection part. It is necessary to prevent this.

  The coating liquid used in the present invention can be stably applied even with a coating liquid having a high viscosity in a region where the shear rate is low, and variation in the coating amount can be suppressed. This is particularly effective for coating liquids having a shear viscosity of 1000 [mPa · s] to 20000 [mPa · s] at a shear rate of 1 [1 / s].

  Examples of the present invention will be described below.

  It compared with the case where it coats using the general gravure coater as shown in FIG. 1, and the case where it coats using the gravure coater which provided the coating part as shown in FIG. 2 of this invention. The coating liquid is a coating liquid containing acrylic resin as a main component and methyl ethyl ketone as a solvent. By adding a cross-linking agent, the shear viscosity at a shear rate of 1 [1 / s] is obtained by Rheometer RS75 manufactured by Hake. What measured 7000 [mPa * s] was used. In the case of a general gravure coater, the evaporation of the solvent progresses over time, the end of the liquid receiving pan becomes a stagnant part, and the gravure roll gradually prevents the liquid from being lifted up. Omission of the coating surface has been observed. On the other hand, if it was the method of this invention, coating was possible without a problem in particular. From the above, the effect of the present invention was confirmed.

  Even if the physical property control of the coating liquid is severe, the present invention relates to a production apparatus that can be coated without any problem with a gravure coater, and any product that is coated with a gravure coater is equally effective.

DESCRIPTION OF SYMBOLS 10 ... Base material 11 ... Backup roll 12 ... Gravure roll 13 ... Liquid receiving pan 14 ... Circulation system 15 ... Liquid feed tank 16 ... Liquid feed pump 17 ... Drying Zone 20 ... Doctor blade 21 ... Liquid receiving pan 22 of the present invention ... Waste liquid recovery pan 23 ... Fountain type nozzle 24 ... Injection port 25 ... Flow of liquid in the liquid receiving pan 26 ... Height to coating liquid surface and pouring port 27 ... Distance between upstream bottom and gravure roll 28 ... Distance between downstream bottom and gravure roll

Claims (5)

  A gravure roll, an arc-shaped liquid receiving pan arranged concentrically with the gravure roll installed to transfer the coating liquid to the gravure roll, and a downstream side in the rotation direction of the gravure roll, A coating apparatus comprising: a pouring port for pouring the coating liquid into a liquid receiving pan from a position higher than the liquid surface of the coating liquid.   The gravure roll, the liquid receiving pan arranged on the gravure roll, and the coating liquid is poured into the liquid receiving pan at a position higher than the liquid level of the coating liquid in the liquid receiving pan on the downstream side in the rotation direction of the gravure roll. The liquid receiving pan has a distance from the bottom of the gravure roll upstream in the rotation direction of the gravure roll to the roll of less than 10 mm and the bottom of the gravure roll in the rotation direction of the bottom to the roll The coating apparatus is characterized in that the distance is 10 mm or more and 100 mm or less.   The coating apparatus according to claim 1, wherein the liquid injection port is installed at a height of 20 mm or more and 100 mm or less in a vertical direction from a liquid surface of the coating liquid.   The manufacturing apparatus according to claim 1, wherein the liquid injection port has a fountain-type nozzle shape. 5. The coating liquid according to claim 1, wherein a coating liquid having a shear viscosity of 1000 [mPa · s] to 20000 [mPa · s] at a shear rate of 1 [1 / s] is used. The coating apparatus of Claim 1.

Images