JP2006272110A - Coating method, coater and coating liquid sucking apparatus to be used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method and a coater which enable a coating film having uniform thickness to be formed on the upper surface of a traveling web by removing a desired amount of the coating liquid from a thicker coating liquid part generated in an edge region on both sides of the coating film formed on the upper surface of traveling web. <P>SOLUTION: A suction roll 10 formed of a porous material having many pores on the outer peripheral surface is brought into contact with the thicker coating liquid part 2a to be generated in the edge region on both sides of the coating film 2 formed on the upper surface of the traveling web while being rotated to suck the coating liquid in the thicker coating liquid part 2a by the porous material and prevent the formation of the thicker coating liquid part. The coating liquid sucked by the suction roll 10 is removed from the suction roll 10 and recovered by a cleaning unit 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for applying a coating liquid to a surface of a continuous film, paper, laminated material, or the like using a die head while continuously running the web, and in particular, a thickness generated in both side edge regions of a coating film. The present invention relates to a technique for preventing film formation.

Conventionally, in the manufacture of optical products, display products, electronic products, etc., as shown in FIG. 3, a web 1 such as a continuous film is continuously run and a desired physical property is obtained by using a die head 6 on the surface thereof. The coating liquid 2 is applied to form the coating film 2. In this type of coating, as shown in FIG. 4 (a), even if the coating liquid is applied to the upper surface of the web 1 with a uniform thickness to form a wet coating film 2, the effect of surface tension is exerted. As a result, a thick film was formed in both side edge regions in the coating width direction, and thick film portions 2a were formed on both side edges of the coating film 2 as shown in FIGS. Such thickening of both side edges of the coating film has various adverse effects on subsequent processes. For example, it is as follows.
-Curling in the paper output unit-In the case of photosensitive materials, poor mask adhesion in the exposure process

Therefore, in order to prevent such thickening, a suction nozzle is installed opposite the thick film portion 2a at a position where the coating film 2 is in a wet state, and the coating liquid of the thick film portion 2 is sucked off. Have been proposed (see, for example, Japanese Patent No. 2775236, Utility Model Registration No. 2522526). However, these methods have a problem that the coating liquid remaining in the portion sucked by the suction nozzle is extremely thin compared to the center, and the effective range of the coating film is narrowed.
Japanese Patent No. 2775236 Utility Model Registration No. 2522526

  The present invention has been made in view of such a situation, and makes it possible to easily remove a desired amount of coating liquid from the thick film portion generated in both side edge regions of the coating film, thereby generating the thick film portion. It is an object of the present invention to provide a coating method and apparatus capable of preventing and widening the effective area of a coating film, and a coating liquid suction apparatus used for removing a desired amount of coating liquid from a thick film portion.

  The invention according to claim 1 of the present application is a continuous coating formed of a porous material having a large number of pores opened on the surface in a coating method in which a coating liquid is discharged from a die head onto a running web. A suction member having a surface is continuously moved along a path where the surface comes into contact with and away from the thick film portions formed on both side edge regions of the coating film formed on the upper surface of the web, and the suction member The coating solution for the thick film portion is sucked to prevent the film from becoming thick. The suction member used here is in the form of a roll in which the outer peripheral surface is formed of a porous material, in the form of an endless belt in which the outer surface is formed of a porous material, or in the form of a long band formed on one side with a porous material. Etc.

  The invention according to claim 2 provides an apparatus for carrying out the coating method according to claim 1 described above, and a web traveling device for continuously running the web, and coating on the upper surface of the running web A die head for applying a liquid, and a coating that is disposed downstream of the die head with respect to the traveling direction of the web and sucks and removes the coating liquid of the thick film portion generated in both side edge regions of the coating film formed on the upper surface of the web A suction member having an endless surface formed of a porous material having a large number of pores opened on the surface, and the surface of the suction member is the upper surface of the web The driving device that drives the suction member so as to continuously move along a path in contact with and away from the thick film portion, and a position that is separate from the position in contact with the thick film portion of the suction member From the surface of the suction member, the table The suction, characterized in that it has a cleaning device for removing a coating liquid is held. Examples of the suction member used herein include a roll-shaped member whose outer peripheral surface is formed of a porous material, and an endless belt-shaped member whose outer surface is formed of a porous material.

  According to a third aspect of the present invention, in the coating apparatus according to the second aspect, the suction member is constituted by a suction roll having an outer peripheral surface formed of a porous material.

  According to a fourth aspect of the present invention, in the coating apparatus according to the second or third aspect, the cleaning device is sprayed from a surface of the suction member and a solvent spray nozzle that sprays a solvent onto the surface of the suction member. And a suction nozzle that sucks and removes the solvent and the coating liquid.

  The invention according to claim 5 is a coating liquid suction device used for sucking and removing the coating liquid of the thick film portion formed on both side edges of the coating film formed on the upper surface of the web, wherein the outer peripheral surface is the surface. A suction roll formed of a porous material having a large number of pores opened to the surface, a driving device for rotationally driving the suction roll, and a surface of the suction roll formed of the porous material for suction to the porous material A coating liquid suction apparatus having a cleaning device for removing the coating liquid being held.

  In the coating method and apparatus of the present invention, a porous material having pores is applied to the thick film portion generated on both side edges of the coating film after application, and the coating solution of the thick film portion is sucked by the capillary force of the liquid. , It can be easily prevented that the coating liquid is sucked excessively, and by removing the appropriate amount of coating liquid by suction, the occurrence of thick film part is prevented and the coating thickness after drying is made full width. It is almost uniform over the entire area, and the effective area of the coating can be expanded.

  In addition, the coating liquid suction device of the present invention is used by being arranged so that a part of the outer peripheral surface of the suction roll is in a position in contact with the thick film portions of the both side edge regions of the coating film formed on the web. Thus, an appropriate amount of the coating liquid can be sucked and removed from the thick film portion, which can contribute to the formation of a uniform thickness coating film.

  FIG. 1 is a schematic perspective view of a coating apparatus according to a preferred embodiment of the present invention, and FIG. 2 is a schematic sectional view of a coating liquid suction apparatus used for the coating apparatus. 1 and 2, a coating apparatus generally indicated by reference numeral 5 applies a coating liquid to a web traveling apparatus (not shown) that continuously travels the web 1 and the upper surface of the traveling web 1. The coating liquid for the thick film portion 2a that is disposed downstream of the die head 6 with respect to the traveling direction of the web 1 and is formed on both sides of the coating film 2 formed on the upper surface of the web 1. Is provided with a coating liquid suction device 7 for sucking and removing the liquid.

  The coating liquid suction device 7 includes a suction roll 10 having an outer peripheral surface formed of a porous material 11 as a suction member having an endless surface formed of a porous material having a large number of pores opened on the surface. Furthermore, a driving device (not shown) for rotating the suction roll 10 to a predetermined position and a cleaning device 14 for removing the coating liquid sucked and held on the surface of the suction roll 10 are provided. . As the porous material 11, a material having a large number of pores and capable of sucking the coating liquid with a capillary force is used. Specifically, a sintered body, a pumice stone, a sponge, a resin foam having communication pores. A body etc. can be illustrated.

  The suction roll 10 is installed so as not to contact the web 1 but to contact only the coating liquid of the thick film portion 2a of the coating film 2 on the web surface. Further, the suction roll 10 is configured to be driven to rotate in the same direction as the traveling direction of the web 1 by a driving device. Therefore, a path in which the roll surface is in contact with and away from the thick film portion 2a on the upper surface of the web. The coating liquid can be continuously sucked and removed from the thick film portion 2a that is continuously moving along and continuously running. Here, the rotational speed of the suction roll 10 is preferably set so that the speed of the outer peripheral surface of the suction roll becomes equal to the traveling speed of the web 1 in terms of the quality of the coating film surface. You may set so that it may differ from speed. By changing the rotation speed of the suction roll 10, the suction amount of the coating liquid can be changed.

  The cleaning device 14 is installed so as to face the outer peripheral surface of the suction roll 10 at a position away from the position in contact with the thick film portion 2 a of the suction roll 10. The cleaning device 14 includes a solvent spray nozzle 16 that sprays a solvent capable of dissolving the coating liquid on the surface of the suction roll 10, a solvent supply device that supplies the solvent to the solvent spray nozzle 16, and the suction roll 10. A suction nozzle 17 for sucking and removing the sprayed solvent and coating liquid from the surface, a vacuum device (not shown) for applying a negative pressure to the suction nozzle 17, and a space between the suction nozzle 17 and the vacuum device And a recovery device (not shown) for recovering the sucked solvent and coating liquid, a cover 18 and the like.

  Next, the coating operation by the coating apparatus having the above configuration will be described. The web 1 travels continuously, and the die head 6 discharges the coating liquid thereon to form the coating film 2. Even if the formed coating film 2 has a uniform thickness at the time of formation, thickening occurs in both side edge regions with the passage of time, and a thick film portion 2a is formed. When the formed thick film portion 2 a passes under the coating liquid suction device 7, the thick film portion 2 a comes into contact with the porous material 11 on the outer peripheral surface of the suction roll 10 rotating in the same direction as the web 1. The coating liquid 2a is sucked and removed from the porous material 11 by capillary force. Here, by appropriately determining the coating liquid suction amount by the porous material 11 (details will be described later), even if the film thickness of the thick film portion 2a is reduced and the film thickness is increased again downstream, The film thickness after drying can be made substantially equal to the film thickness in the central region. On the other hand, in the coating liquid suction device 7, the region where the coating liquid on the surface of the suction roll 10 is sucked passes through the cleaning device 14 by the rotation of the suction roll 10, and the solvent is sprayed from the solvent spray nozzle 16. Then, the coating liquid is diluted and then sucked and removed by the suction nozzle 17. As a result, the surface of the suction roll 10 is regenerated so that there is almost no coating liquid, and then comes into contact with the thick film part 2a on the web 1 and is used again for sucking the thick film part 2a. As described above, the coating liquid of the thick film portion 2a on the upper surface of the web 1 running continuously can be continuously sucked and removed by the coating liquid suction device 7, and after the coating film is dried, A coating film having a uniform thickness over almost the entire coating width can be formed. Therefore, almost the entire width of the coating film 2 formed on the upper surface of the web 1 can be set as the effective region.

Here, the suction of the coating liquid from the thick film portion 2a by the porous material 11 of the suction roll 10 is mainly performed by the capillary force of the porous material 11, and the suction liquid amount Q is obtained by the following equation. be able to.
Q = H × S × F
H: Height of liquid pulled up by capillary force S: Contact area between coating liquid and suction roll (porous material 11) F: Opening ratio of contact surface between suction roll (porous material 11) and coating liquid Moreover, the height H of the liquid pulled up by capillary force can be calculated | required with the following formula | equation.
H = (2T cos θ / ρg) / R
T: surface tension of coating liquid θ: contact angle between suction roll (porous material 11) and coating liquid ρ: density of coating liquid g: acceleration of gravity R: pore size of suction roll (porous material 11) radius

  Therefore, by appropriately setting the above-described characteristics using the above formula or by performing an experiment, the suction liquid amount Q by the suction roll 10 can be set as desired. By setting Q so that the film thickness after re-thickening after suction of the coating liquid from the thick film portion 2a occurs is equal to the film thickness of the central region of the coating film, An appropriate amount of the coating solution is sucked and removed from the portion 2a, and a coating film can be formed in which the film thickness after drying is substantially uniform over the entire width.

A coating test was performed using the coating apparatus shown in FIG. 1 under the following specifications and conditions.
Web material: PET film thickness 50μm x width 300mm
Coating liquid: acrylic resin solution, viscosity 10 cp
Application width (die head discharge width): 280 mm
Coating thickness (wet state): about 100 μm
Web running speed: 5m / min Coating liquid suction device specifications Suction roll: Outer diameter 50mm x Width 7mm
Porous material 11: sintered metal (average radius of pores: about 500 μm)
Suction roll rotation speed: 32 rpm
Distance from die head to suction roll: 100mm

  During coating, the thickness of the coating film (wet state) immediately downstream of the coating liquid suction device 7 and the coating film thickness after drying were measured, and the results shown in Table 1 were obtained. For comparison, a similar coating test is also performed by a coating apparatus that does not include the coating liquid suction apparatus 7, and the coating film (wet state) at a position immediately downstream of the coating liquid suction apparatus in the example is used. ) And the coating thickness after drying were measured and the results shown in Table 1 were obtained.

  As is apparent from Table 1, by providing the coating liquid suction device 7, the thick film portion having a thickness of 230 μm generated in the side edge region can be reduced to 90 μm, and after drying, the side edge is dried. A coating with a thickness approximately equal to the central region could be formed. This confirmed that the effective area of application could be expanded.

  The preferred embodiments and examples of the present invention have been described above, but the present invention is not limited to these embodiments and examples, and can be appropriately changed within the scope of the claims. . For example, although the suction roll 10 is used as the suction member in the above-described embodiment, the suction member is not limited to the roll shape, and may be an endless belt shape. In that case, a flexible material that forms the surface may be used. When an endless belt-like suction member (referred to as a suction belt) is used, the suction belt is installed so that a part of the suction belt is in contact with the thick film portion 2a on the upper surface of the web, and the suction belt is run. As in the case of the suction roll 10, the surface of the porous material can be continuously brought into contact with the thick film portion 2a to suck and remove the coating liquid of the thick film portion 2a. By providing the cleaning device at a position away from the position in contact with the part, the solvent and coating liquid sucked and held on the suction belt can be removed, and the suction belt can be used continuously.

Schematic perspective view of a coating apparatus according to a preferred embodiment of the present invention Schematic sectional view of coating liquid suction device Schematic perspective view of a conventional coating apparatus (A) is a schematic cross-sectional view showing the web and coating immediately after coating cut in the width direction, and (b) is a schematic cross-sectional view illustrating a state in which a thick film portion is formed in the side edge region of the coating

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Web 2 Coating film 2a Thick film part 5 Coating apparatus 6 Die head 7 Coating liquid suction apparatus 10 Suction roll (suction member)
DESCRIPTION OF SYMBOLS 11 Porous material 14 Cleaning apparatus 16 Solvent spray nozzle 17 Suction nozzle 18 Cover

Claims (5)

  A step of discharging and applying a coating liquid from a die head to the upper surface of a running web, and a suction member having a continuous surface formed of a porous material having a large number of pores opened on the surface, A step of continuously moving along a path that contacts and separates from the thick film portion generated in both side edge regions of the coating film formed on the upper surface of the web, and sucks the coating liquid of the thick film portion with the suction member The coating method characterized by having.   A web traveling device that continuously travels the web, a die head that applies a coating liquid to the upper surface of the traveling web, and a coating film that is disposed downstream of the die head in the traveling direction of the web and is formed on the upper surface of the web A coating liquid suction device that sucks and removes the coating liquid of the thick film portion generated in the both side edge regions of the coating, and the coating liquid suction device is formed of a porous material having a large number of pores opened on the surface. A suction member having an endless surface, and a drive for driving the suction member so that the surface of the suction member continuously moves along a path in contact with and away from the thick film portion of the upper surface of the web And a cleaning device that removes the coating liquid sucked and held on the surface from the surface of the suction member at a position away from the position where the apparatus contacts the thick film portion of the suction member. Coating equipment.   The coating apparatus according to claim 2, wherein the suction member is a suction roll having an outer peripheral surface formed of the porous material.   The cleaning apparatus includes a solvent spray nozzle that sprays a solvent onto a surface of the suction member, and a suction nozzle that sucks and removes the solvent sprayed from the surface of the suction member and a coating liquid. Item 2. A coating apparatus according to item 2 or 3.   A coating liquid suction device used for sucking and removing the coating liquid of the thick film portion generated in both side edge regions of the coating film formed on the upper surface of the web, wherein the outer peripheral surface has a large number of pores opened to the surface. A suction roll formed of a porous material having a surface, a driving device for rotationally driving the suction roll, and a coating that sucks and holds the porous roll from the surface of the suction roll formed of the porous material. A coating liquid suction device having a cleaning device for removing the liquid.

Images