JP4894587B2 - Coating method and coating apparatus - Google Patents

Description

  The present invention relates to a coating method and a coating apparatus.

  Generally, there is a rod coating method as a method for uniformly applying a coating liquid to a predetermined thickness on the surface of a web such as a thermoplastic resin film. An example of this rod coating method is shown in FIG. FIG. 13 is an explanatory view of a coating apparatus described in Patent Document 1 as a conventional rod coating method for applying a coating liquid to a web that is continuously conveyed, and is a coating supported by a support 35 having a V-shaped cross section. The liquid adhering bar 3-1 and the measuring bar 3-2 supported by the support body 35 having the same V-shaped cross section are pressed against the web 8 to be continuously conveyed and rotated, and the coating liquid 2 is It is supplied from the supply port 20. An excessive amount of coating liquid was applied to the lower surface of the web 8 with the coating liquid adhesion bar 3-1, compared with the final target coating thickness, and then placed downstream in the conveyance direction of the web 8 (illustrated by arrows). This is a coating method in which excess coating liquid is scraped off by the measuring bar 3-2 to obtain a constant thickness. However, in this coating method, the coating liquid adhering bar 3-1 and the metering bar 3-2 cause a rotation defect due to friction with the support 35 having a V-shaped cross section, resulting in streak-like defects. Alternatively, the support 35 having a V-shaped cross section is abraded by the rotation of the coating liquid adhering bar 3-1 and the measuring bar 3-2, and this abrasion powder is applied to the web together with the coating liquid, so that a foreign matter defect is caused. May occur. Therefore, a method of supporting the coating bar with a rotatable support is known, and this will be described with reference to FIG. FIG. 14 is an explanatory view of a coating apparatus described in Patent Document 2 as a conventional rod coating method for applying a coating liquid to a web that is continuously conveyed. In FIG. 14, reference numeral 1 denotes a container containing the coating liquid 2, and an excessive amount of coating liquid is adhered to the web 8 by the roll 36 compared to the final target coating thickness. Next, the excess coating liquid is scraped off by the coating bar 3 installed on the downstream side in the conveyance direction of the web 8 to obtain a constant thickness, and the excess coating liquid scraped off flows on the plate 37 at that time. , Returned to the container 1. Here, 3 is a rotatable support, which supports the coating bar 3 from below. Since the rotatable support 4 is driven and rotated by the coating bar 3, no wear debris is generated. However, in the case of the present coating apparatus, according to the knowledge of the present inventors, the coating bar 3 in a state where the coating liquid remains thinly on the surface and the rotatable support 4 rotate in contact with each other, so that the contact portion between the two In some cases, the bubbles are entrained and applied to the web 8 together with the coating liquid remaining on the surface of the coating bar 3 and then repelled on the web. As a technique for preventing this, there is a method in which coating is performed in a state where a contact portion between a coating bar which is a bubble generation source and a rotatable support is submerged in the coating liquid. This will be described with reference to FIG. FIG. 15 is an explanatory view of a coating apparatus described in Patent Document 3 as a conventional rod coating method for applying a coating liquid to a web or substrate that is continuously conveyed. Reference numeral 1 denotes a container containing a coating liquid 2, and a coating bar 3 is disposed in the vicinity of the liquid surface of the coating liquid 2, and the coating bar 3 is supported by a support 4 that can rotate in the container. A rotating roller 5 is provided on the upper side of the container 1 so as to face the coating bar 3, and the substrate conveyed by the conveying roller 6 is inserted between the rotating roller 5 and the coating bar 3, and the rotating roller 5 and the coating bar 3 while being pressed. Thereby, the coating liquid 2 is adhered to the peripheral surface of the coating bar 3 while the coating bar 3 rotates, and the adhered coating liquid 2 is applied to the substrate 7. In the present coating apparatus, the contact portion between the coating bar 3 and the rotatable support 4 is located in the coating liquid, so that it is difficult to entrap bubbles at the contact portion. However, according to the knowledge of the present inventors, when the coating speed is high, the liquid surface is waved and bubbles are generated by the accompanying flow generated in the coating liquid by the rotation of the coating bar 3 and the rotatable support 4. There is. The generated bubbles flow in the container together with the coating liquid, and are scraped up by the coating bar 3 and applied to the base 7.

  Based on the knowledge of the present inventors, this phenomenon will be described in detail with reference to an example in which application to a web that is continuously conveyed using the technique of Patent Document 3 is performed. FIG. 6 is a schematic cross-sectional view of a coating apparatus that applies a coating solution using a coating bar to a web that is continuously conveyed using the technique of Patent Document 3. In FIG. 6, a coating bar 3 is installed near the liquid surface of the coating liquid 2 in the container 1, and this coating bar 3 is supported by a rotatable support 4. The coating bar 3 rotates by being pressed against the web 8 to be conveyed, and applies the coating liquid adhering to the outer peripheral surface of the coating bar 3 to the web 8. 7 and 8 are enlarged views of the vicinity of the coating bar when coating is performed by the apparatus of FIG. 6, and FIG. 17 is a schematic view of the coating bar surface. As shown in FIG. 7, an accompanying flow 11 is generated by the rotation of the coating bar 3 and the support 4 at the time of application. The rotational speeds of the coating bar 3 and the support 4 are substantially the same as the web conveyance speed, and the accompanying flow 11 increases as the conveyance speed increases. Therefore, for example, at the time of high-speed application of 30 m / min or more, the developed wake 11 causes the liquid surface 12 on the downstream side in the conveyance direction of the web 8 to pulsate unstablely as indicated by the dotted line, and at the contact 13 with the coating bar 3. The bubble 14 may be bitten. This is because, for example, when a groove is formed on the surface of the coating bar 3 by winding the wire 18 around the rod 17 as shown in FIG. 17, bubbles are easily trapped in the groove. Therefore, as shown in FIG. 7, the air bubbles caught at the contact point 13 between the liquid surface 12 and the coating bar 3 are trapped in the groove of the coating bar 3, reach the application surface by the rotation of the coating bar 3, and are applied. As a result, a defect 15 in the form of coating missing may occur. Further, when the web conveying speed is further increased, the liquid level 12 greatly drops to the contact 16 between the coating bar 3 and the support 4 as shown in FIG. 8, and bubbles are generated by the rotation of the coating bar 3 and the support 4. In some cases, a coating-like defect may occur.

Such defects due to coating omission due to air bubbles have been regarded as a problem not only in the rod coating method but also in the roll coating method, and as a technique for solving this defect, for example, a technique described in Patent Document 4 It has been known. This technique will be described with reference to FIG. FIG. 16 is an explanatory view of a coating apparatus described in Patent Document 4 as a conventional roll coating method for coating a web with a coating liquid. Reference numeral 1 denotes a container containing the coating liquid 2, and a pickup roll 38 is immersed in the liquid surface. The coating liquid 2 is scraped up by rotating the pickup roll 38. Reference numeral 39 denotes a partition weir, which is used to keep the air bubble 40 in a certain place in order to prevent the air bubble 40 generated in the container from being picked up by the pickup roll 38 together with the coating liquid. However, since the present technology does not prevent the generation of bubbles per se, the amount of bubbles accumulated in the partition weir 39 increases with time, and may eventually overflow from the partition weir 39.
JP 2003-275743 A Japanese Examined Patent Publication No. 6-49169 Japanese Patent Laid-Open No. 10-5650 Japanese Utility Model Publication No. 4-122670

  An object of the present invention is to provide a coating apparatus and a coating method capable of preventing the entrapment of bubbles at a coating portion even during high-speed coating and suppressing the occurrence of coating defects caused by bubbles.

  In order to achieve the above object, the present invention provides a container having a coating liquid inlet, and an upstream upper end and a downstream upper end forming an opening having a longitudinal direction in the longitudinal direction of the container at the upper part of the container. And a rotatable coating bar disposed in the opening portion so as to be sandwiched between the upstream upper end portion and the downstream upper end portion and arranged with a rotation axis direction in a longitudinal direction of the opening portion, The coating liquid is introduced into the container by using a coating apparatus that is disposed intermittently along the longitudinal direction of the coating bar and has a rotatable support body that supports the coating bar from below in the container. The coating bar was immersed in the coating liquid while supplying the coating liquid from the mouth, the coating bar was pressed against the web transported from the upstream side to the downstream side at a predetermined speed, and the coating bar was scraped up. An application method for applying the coating liquid to the web, As the upper end portion, at least a part of the upper surface of each upper end portion is inclined downward by 10 ° or more and 90 ° or less from the horizontal direction as it moves away from the opening side in the upstream direction and the downstream direction, and the coating bar The first gap located on the upstream side with respect to the rotation direction of the coating bar from the contact point between the coating bar and the web is 3 mm or less, and is located on the downstream side. The second gap is 2 mm or less, and the supply of the coating liquid to the container causes the coating liquid to leak to the upper surface of each upper end from between the opening and the coating bar. The application method is characterized by being performed as described above.

  Further, according to a preferred embodiment of the present invention, the container is provided in a state where it is immersed in the coating liquid on the downstream side with respect to the rotation direction of the coating bar from the contact point between the web and the coating bar, There is provided a coating method using a weir member for suppressing an accompanying flow generated by the rotation of the coating bar and the support body from flowing toward the second gap.

  According to a preferred embodiment of the present invention, the dam member has an end extending in the longitudinal direction of the coating bar with a third gap of 1 mm or less with the outer peripheral surface of the coating bar, and When the coating bar, the weir, and the support are viewed from above in a state without each upper end, the web, and the coating liquid, the vertical passing through the rotation axis of the coating bar among the support There is provided a coating method in which a rotary shaft on the dam side with respect to a surface is provided so as not to be directly visible from a portion other than the third gap.

  Moreover, according to the preferable form of this invention, the coating method which arrange | positions the thing whose length of the axial direction of this support body is 3-25 mm as a said support body along the longitudinal direction of a coating bar is provided. Is done.

  According to another aspect of the present invention, a container having a coating inlet, an upstream upper end and a downstream upper end forming an opening having a longitudinal direction in the longitudinal direction of the container at the upper part of the container; A rotatable coating bar disposed in the opening so as to be sandwiched between the upstream upper end and the downstream upper end, with the rotation axis oriented in the longitudinal direction of the opening, and the coating A plurality of intermittently arranged along the longitudinal direction of the work bar, a rotatable support body for supporting the coating bar from below in the container, and each upper end between the opening and the coating bar. A coating liquid supply means for supplying the coating liquid into the container so as to leak the coating liquid on the upper surface of the unit, and the coating bar is conveyed from the upstream side to the downstream side at a predetermined speed. The coating liquid pressed against the web and scooped up by the coating bar is applied to the web. And at least a part of the upper surface of each upper end portion is inclined downward by 10 ° or more and 90 ° or less from the horizontal direction as the distance from the opening side to the upstream direction and the downstream direction is increased. And among each gap | interval between the said coating bars, the 1st gap | interval located in the upstream with respect to the rotation direction of the said coating bar from the contact of the said coating bar and the said web is 3 mm or less, Thus, a coating apparatus in which the second gap located on the downstream side is 2 mm is provided.

  Further, according to a preferred embodiment of the present invention, the container is provided in a state where it is immersed in the coating liquid on the downstream side with respect to the rotation direction of the coating bar from the contact point between the web and the coating bar, There is provided a coating apparatus having a weir member for suppressing the accompanying flow generated by the rotation of the coating bar and the support body from flowing toward the second gap.

  According to a preferred embodiment of the present invention, the dam member has an end extending in the longitudinal direction of the coating bar with a third gap of 1 mm or less from the outer peripheral surface of the coating bar, and the When the coating bar, the weir, and the support are viewed from above in a state without each upper end, the web, and the coating liquid, the vertical passing through the rotation axis of the coating bar among the support A coating apparatus is provided in which a rotary shaft on the dam side with respect to the surface is not directly visible from a portion other than the third gap.

  Moreover, according to the preferable form of this invention, the length of the axial direction of the said support body is 3-25 mm, and the coating device arrange | positioned in zigzag form along the longitudinal direction of the said coating bar is provided. The

  In the present invention, “web” refers to a sheet-like material such as a thermoplastic resin film, paper, leather, non-woven fabric, and cotton fabric. Typical examples include thermoplastic resin films mainly composed of polyethylene terephthalate, polypropylene, nylon and the like.

  According to the coating apparatus and the coating method according to the present invention, as described below, it is possible to prevent the entrapment of bubbles in the coating portion by preventing the liquid level from dropping and pulsating even during high-speed coating on the web. It is possible to suppress the occurrence of coating defects due to bubbles.

  Hereinafter, an example of the best mode of the present invention will be described with reference to the drawings.

  First, the apparatus configuration of this embodiment will be described. 1 is a schematic longitudinal sectional view of the present embodiment, FIG. 2 is a top view of FIG. 1 viewed from the Z direction, FIG. 3 is an enlarged view of FIG. 1, and FIG. 4 is a side view of FIG. .

  The coating apparatus of the present embodiment includes a container 1 having a coating liquid inlet 20, a coating bar 3 immersed in the coating liquid 2, a rotatable support 4 for supporting the coating bar 3, and a web. 8 and a weir 21 provided so as to be immersed in the coating liquid on the downstream side with respect to the rotation direction of the coating bar 3 from the contact point a of the coating bar 3. Here, “submerged” means that the entire object (here weir) is in the coating liquid, and “soaked” means that a part of the object (here coating bar) is in the coating liquid. Say the state. Needless to say, the coating liquid remains thinly on the surface of the coating bar being applied, but this portion is not in the state of being in the coating liquid. The same applies hereinafter.

  In the upper part of the container 1, an upstream upper end 22 and a downstream side are located upstream and downstream in the conveying direction of the web 8 with respect to the coating bar 3 (shown by arrows at the end of the web 8 in FIG. 1). There is an upper end 23, thereby forming an opening having a longitudinal direction in the longitudinal direction of the container 1 (in this embodiment, the Y direction of the coordinate axis shown in FIG. 2). In the opening, the coating bar 3 is arranged with the rotation axis direction in the longitudinal direction of the opening (in this embodiment, the Y direction of the coordinate axis shown in FIG. 2), and the upstream upper end 22 and the downstream A first gap 24 and a second gap 25 which are the shortest distances from the coating bar 3 are formed between the upper end portion 23 and the upper end portion 23, respectively.

  The coating bar 3 is rotatably supported by bearings or the like (not shown) at both ends, and further from below by a rotatable support body 4 that is intermittently disposed along the longitudinal direction of the coating bar 3. It is supported externally. Further, the coating bar 3 is pressed against the web 8 conveyed from the upstream side to the downstream side at a predetermined speed and is driven to rotate, and the support 4 supporting the coating bar 3 is similarly rotated. The end of the weir 21 is close to the coating bar 3 and forms a gap 26 that is the shortest distance from the coating bar 3.

As the coating bar 3, for example, a rod, a wire bar in which a wire is wound around the outer peripheral surface of the rod to form a groove, a rolling rod in which a groove is formed in the outer peripheral surface of the rod by rolling, and the like can be used. The material of the coating bar 3 is preferably stainless steel, particularly SUS304 or SUS316. The surface of the coating bar 3 may be subjected to a surface treatment such as hard chrome plating.
If the diameter of the coating bar 3 is large, streak-like coating defects along the transport direction called rib streaks are likely to occur, so 10 to 15 mm is preferable. In the present embodiment, the coating bar 3 is pressed against the web 8 and rotated by a frictional force with the web 8, which is a so-called driven rotation state. However, the coating bar 3 may be rotated by a driving device such as a motor. At this time, in order to prevent the web from being damaged, it is preferable that the coating bar is rotated in the web conveyance direction at substantially the same speed as the web conveyance speed. Here, “substantially substantially the same speed” means that the speed difference between the peripheral speed of the coating bar and the web conveyance speed is rotated by ± 10% or less. However, depending on the use of the product or the like, if the web does not become a problem, the coating bar may be rotated at a speed different from the web conveyance speed, or may be rotated in the direction opposite to the web conveyance direction. Further, the winding angle α (α in FIG. 1), which is an angle formed by the upstream web and the downstream web with respect to the conveyance direction of the web 8 from the contact point a between the coating bar 3 and the web 8, is small. If it is too large, a horizontal dang-like coating defect due to web fluttering or vibration will occur, and conversely if it is too large, a bubble streak defect will occur, so it is preferably in the range of 8 to 20 degrees.

  The support 4 may be any material such as a roller or a ball that supports the coating bar while rotating. Further, in order to reduce the wear of the coating bar 3, the support 4 is preferably made of a material having a lower hardness than the coating bar 3 for the surface layer, and a synthetic rubber or an elastomer is preferably used as the surface layer material. . Here, the elastomer refers to a rubber-like elastic resin that can be melt-molded by an injection molding method, an extrusion molding method, a casting molding method, a blow molding method, an inflation molding method, or the like. As the elastomer, urethane elastomer, polyester elastomer, polyamide elastomer and the like are preferable, and it is particularly preferable to use a thermoplastic polyurethane elastomer excellent in wear resistance and mechanical strength. The thickness of the elastomer formed on the surface layer of the support 4 is preferably 0.5 to 6 mm. The hardness of the elastomer is preferably 60 to 98A (measured according to the standard of JIS K6253 in 1996).

Further, in order to prevent the coating bar 3 from bending in the conveyance direction of the web 8, the support 4 may be arranged on both the upstream side and the downstream side of the coating bar 3 with respect to the conveyance direction of the web 8. Preferably, further, upstream and downstream supports are alternately arranged (staggered) in the longitudinal direction of the coating bar.
In addition, a line connecting the rotation axis of the support disposed upstream and downstream of the coating bar 3 with respect to the web conveyance direction and the rotation axis of the coating bar 3 is a vertical vertical direction. The angles β1 and β2 (shown in FIG. 1) are preferably 10 degrees or more. If the angles β1 and β2 are too small, the coating bar may vibrate due to the vibration of the web, and coating defects may occur. In addition, if there is vibration or unevenness in the rotation of the support 4, they are transmitted to the coating bar and are liable to cause coating defects, so that the support preferably has a structure having a bearing so that the support rotates smoothly. Since the support is submerged in the coating liquid, the material of the bearing is preferably a material that is highly corrosive to the coating liquid, and more preferably waterproof. The diameter of the support is preferably 8 mm or more because a commercially available bearing can be used. Moreover, in order to make the accompanying flow to generate | occur | produce small and a general purpose bearing can be used, the length of 3-25 mm of the axial direction of a support body is preferable.

  If a large load is applied to the support, the surface of the support will be worn out, the life of the bearing will be shortened and frequent replacement will be required. Therefore, a large number of supports are installed in the longitudinal direction of the coating bar, and one support is installed. It is preferable to reduce the load applied to the hit.

  In FIG. 3, the vertical distance h <b> 1 between the surface of the support located on the downstream side of the coating bar 3 with respect to the conveyance direction of the web 8 and the web 8 located directly above the tip of the downstream upper end 23. Is determined by the diameter of the coating bar and the support, the winding angle α, and the angle β2, but in order to secure the installation space for the upper end portion and the weir member, the diameter of the coating bar and the support, and the winding angles α and β2 It is preferable to adjust within the preferable range described above to be 10 mm or more. Similarly to h1, the distance h2 in the vertical direction between the upstream support surface and the web 8 directly above is preferably 8 mm or more.

  Next, the flow of the coating liquid of this embodiment will be described. In the coating apparatus of this embodiment, the coating liquid 2 is sequentially supplied from the coating liquid introduction port 20 by a coating liquid supply means (not shown) to fill the inside of the container, and a part of the coating liquid 2 is scraped up by the coating bar 3. 8 and the rest are a first gap 24 and a second gap 25 which are gaps in the web conveying direction provided between the upper part of the container 1 and the coating bar 3 on the upper side of the container 1. It leaks out of the container sequentially from 30 (shown by hatching in FIG. 4), which is a gap with the bar, and other gaps (such as a gap in the container itself; not shown).

  As the coating liquid supply means, a gear pump, a diaphragm pump, or a mono pump having quantitativeness and low pulsation is preferable. Moreover, you may supply the coating liquid discharged from the pump to a container through defoaming means, such as a filter. The supply of the coating liquid to the container may be distributed and supplied from several places in the container. By doing so, the amount of leakage from the first gap 24 and the second gap 25 can be made uniform in the width direction.

  As described above, in particular, by causing the coating liquid to leak from the second gap 25, the liquid level 12 on the downstream side in the web conveying direction of the coating bar 3 due to the rotation of the coating bar 3 and the support 4 in the second gap. Since descent can be suppressed, it is possible to prevent entrapment of bubbles at the contact portion between the support and the coating bar.

  Here, according to the present embodiment, the first gap 24 is preferably 3 mm or less, and the second gap 25 is preferably 2 mm or less. In order to prevent the liquid level 12 on the downstream side in the web conveying direction of the coating bar 3 from dropping, it is necessary to push back the liquid level 12 to be lowered by the rotation of the coating bar 3 and the support 4 with the liquid pressure in the container. There is.

  Since the pressure loss in the portion where the coating liquid leaks greatly affects the magnitude of the fluid pressure in the container, the first gap 24 and the second gap 25 which are leaking portions, the side surface of the container in the Y direction in FIG. The hydraulic pressure increases as the gap 30 (shown in FIG. 4) between the coating and the coating bar and other gaps (gap in the container itself, etc., not shown) are smaller and the supply amount of the coating liquid is larger. Since the distance at which the liquid level 12 descends is affected by the rotational speed of the coating bar and the support, the size of the gap between the leaking portions and the supply amount of the coating liquid may be adjusted according to these conditions. It is preferable that the liquid surface 12 does not contact the support 12 and the liquid surface 12 located downstream of the coating bar 3 with respect to the conveyance direction of the web 8, and the liquid surface 12 does not contact the weir 21. More preferably.

  However, if the amount of leakage from the second gap 25 increases as a result of increasing the supply amount to increase the liquid pressure, the coating liquid ejected from the gap may adhere to the application surface, which may cause a coating defect. . Further, when the amount of leakage from the first gap 24 is large, the liquid pool 32 downstream of the coating bar may be disturbed by the leaked coating liquid, resulting in coating unevenness. Therefore, the first gap 24 and the second gap 25 are preferably small so that the liquid pressure in the container is sufficiently high even if the supply amount of the coating liquid is small. In particular, the first gap 24 is 3 mm or less, The second gap 25 is preferably 2 mm or less. Further, the size of the gap 30 between the side surface of the container in the Y direction and the coating bar in FIG. 2 and other gaps (such as the gap of the container itself; not shown) is not particularly specified, but if it is large, the liquid pressure of the container is increased. For this reason, the supply amount of the coating liquid is increased, and a load is imposed on the pump.

  In FIG. 3, the vertical distance h <b> 3 between the surface of the support located downstream of the coating bar 3 with respect to the conveyance direction of the web 8 and the lower end of the distal end of the downstream upper end 23 is the installation of the weir 21. 7 mm or more is preferable for securing a space. Further, if the distance h4 between the upper end of the distal end of the downstream upper end 23 and the web 8 immediately above it is too small, the coating liquid on the distal end of the downstream upper end 23 comes into contact with the coating surface and is 3 mm or more. Preferably there is.

  Further, the upstream upper end portion 22 and the downstream upper end portion 23 are inclined by 10 ° or more and 90 ° or less downward from the horizontal direction as at least a part thereof is separated from the opening side in the upstream direction and the downstream direction. It is preferable. As a result, the coating liquid leaking from the first gap and the second gap accumulates on the upper surface of each upper end portion and comes into contact with the web, or the liquid pool 32 on the upstream side of the coating bar is disturbed to cause uneven coating. Can be prevented.

  In addition, according to the present embodiment, the third gap 26 indicating the shortest distance between the weir 21 and the outer peripheral surface of the coating bar 3 is preferably 1 mm or less. If there is no problem even if it is mixed in the film, it is more preferable to bring it into contact. By doing in this way, it can prevent that the liquid level 12 pulsates by the accompanying flow generated by rotation of the support body 4. FIG. This phenomenon will be described with reference to FIG. FIG. 5 is an enlarged view of the vicinity of the coating bar when coating is performed by the coating apparatus of FIG. At the time of application, as shown in FIG. 5, accompanying flows 11 and 11-a are generated by the rotation of the coating bar 3 and the support 4. However, by setting the third gap, which is the shortest distance between the weir 21 and the coating bar 3, to 1 mm or less, the flow of the accompanying flow 11-a, which is one of the accompanying flows, becomes dominant, and the other accompanying flows 11 cannot rise in the third gap 26, so that the liquid level 12 does not pulsate. Further, when the weir 21 is brought into full contact with the coating bar 3, the accompanying flow 11 does not flow toward the liquid surface 12, so that the liquid surface 12 does not pulsate. Further, when the coating bar, the weir, and the support are viewed from vertically above without the web and the coating liquid, the weir 21 has a weir with respect to a vertical plane that passes through the rotation axis of the coating bar of the support. It is preferable to provide a shaft with a rotating shaft on the side so that it is not directly visible from a portion other than the third gap 26 with the outer peripheral surface of the coating bar, more preferably not only directly above the support 4, It is good to provide over the full width of a container like FIG. By doing so, it is possible to prevent the accompanying flow generated by the support from flowing in the width direction of the web and pulsating the liquid surface in a portion where there is no support. Here, “not directly visible” refers to a state where there is a weir on the line of sight to the support when the support is viewed under the above conditions. Therefore, for example, when there is a weir made of a transparent material on the line of sight, even if the support can be visually observed, it is viewed through the transparent weir, so that it is “not directly visible”.

  Further, the inclination angle γ (shown in FIG. 3), which is the angle formed by the weir 21 with the horizontal line, is not particularly limited. In this embodiment, each side of the weir is straight, but it may be bent or the tip may be rounded.

  Moreover, it is preferable that the weir 21 is a position which does not contact the liquid level 12. When the weir 21 and the liquid surface 12 come into contact with each other, as shown in FIG. 5, the liquid surface is disturbed by the accompanying flow 11 -a and descends the gap 26 which is the shortest distance from the coating bar 3. May bite bubbles.

  Depending on the use of the product and the like, if weirs and support debris are not a problem even if they are mixed in the coating film, the weir 21 and the support may be brought into contact with each other.

  Further, the weir 21 may be similarly installed on the opposite side to the coating bar. By carrying out like this, it can suppress that the liquid pool 32 pulsates by the accompanying flow of a coating bar or a support body.

  FIG. 11 is a schematic cross-sectional view showing another embodiment of the present invention. As shown in the figure, the container 1 is provided so as to surround the support 4 that is one of the causes of the accompanying flow. Also good.

  FIG. 12 is a schematic sectional view showing another embodiment of the present invention. As shown in this figure, the inside of the container is divided into three parts A, B, and C by the weir 21 and the coating liquid supply port 20a. , 20c, and 20d may be supplied to the respective sections, and the coating liquid in section C may be discharged from the coating liquid discharge port 20b. Further, in this embodiment, the sections A, B, and C are completely divided, but the coating liquid may be allowed to go back and forth in the sections A, B, and C by increasing the gap between the weir and the coating bar. .

  Moreover, as materials of the upstream side upper end part 22, the downstream side upper end part 23, and the weir 21, metals such as iron, stainless steel, aluminum, copper, nylon, acrylic resin, vinyl chloride resin, tetrafluoroethylene, etc. Synthetic fats or rubbers can be used. Among these, a more preferable material is a synthetic resin, rubber, or the like that does not damage the surface of the coating bar even when it comes into contact with the coating bar when the gap is adjusted or attached. Further, the weir 21 may be anything that suppresses the accompanying flow, and may be a plate-like one or a mesh-like one.

  The viscosity of the coating liquid is preferably 0.1 Pa · s or less. When the viscosity of the coating liquid is high, the coating liquid becomes streaks when the coating liquid in the container is swollen by the coating bar, and the coating cannot be uniformly applied in the width direction of the web, resulting in a coating streak. In this embodiment, the viscosity of the coating liquid is measured according to the standard of JIS Z8803 using a rheometer (RC20 manufactured by Rheotech). At this time, it is ideal to use the temperature of the coating liquid in the actual application part as the measurement condition, but it is difficult to accurately know the temperature of the coating liquid in the application part. Therefore, the temperature at the center of the puddle may be measured with a radiation thermometer, and a temperature close to the temperature of the application part may be used. The rotational peripheral speed of the coating bar is preferably 100 m / min or less. When the rotational peripheral speed exceeds 100 m / min, application stripes are likely to occur.

Moreover, 2-100 g / m < ² > is preferable in the wet state immediately after application | coating, and, as for the application quantity of the coating liquid 2, 4-50 g / m < ² > is more preferable. The coating amount can be adjusted by the size of the groove formed in the coating bar 3. When the coating bar 3 is a wire bar, the diameter of the groove is changed by changing the wire diameter of the wire to be wound. When the coating bar 3 is a rolling rod, the groove is rolled with a die having a different groove depth and / or groove pitch. It can be changed by processing.

  Further, the coating according to the present embodiment may be performed inline on the web during film formation, or may be performed off-line on the manufactured web.

  The apparatus configuration when performing in-line coating on the web being manufactured will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is a schematic diagram showing an embodiment of a web manufacturing process, and FIG. 10 is a schematic diagram of a process when coating is performed in-line during the web manufacturing process of FIG. As shown in FIG. 9, the web manufacturing process includes an extruder 200, a base 201, a casting drum 202, a longitudinal stretching machine 203, a lateral stretching machine 204, and a winding roll 205. The polymer is extruded, passed through the die 201 and the casting drum 202, and then the polymer is formed into a web shape. Thereafter, the formed web is stretched vertically and horizontally by a longitudinal stretching machine 203 and a lateral stretching machine 204, and the stretched web is continuously wound by a winding roll 205. When applying in-line to a web under production, as shown in FIG. 10, for example, a coating device 206 is installed between the longitudinal stretching machine 203 and the lateral stretching machine 204 to apply the coating to the web after longitudinal stretching. Do. Here, an example of a sequential biaxial stretching method in which transverse stretching is performed after longitudinal stretching has been shown, but the present coating apparatus may be installed before the simultaneous biaxial stretching method.

Next, although the said embodiment is described concretely based on an Example, the said embodiment is not necessarily limited to the following examples.
[Example 1]
A chip of polyethylene terephthalate (hereinafter abbreviated as PET) of intrinsic viscosity 0.62 dl / g (measured in o-chlorophenol at 25 ° C. according to the standard of JIS K7367 in 1996) at 180 ° C. After sufficiently vacuum-drying, it is supplied to the extruder 200 shown in FIG. 10, melted at 285 ° C., extruded into a sheet form from the T-shaped base 201, and a mirror cast drum having a surface temperature of 23 ° C. using an electrostatic application casting method It was wound around 202 and solidified by cooling to obtain an unstretched film. Subsequently, in the longitudinal stretching machine 203, the unstretched film was heated with a roll group heated to 80 ° C., and further stretched 3.2 times in the longitudinal direction while being heated with an infrared heater, and a cooling roll adjusted to 50 ° C. It cooled and set it as the resin film of uniaxial stretching. The width of the resin film was 1700 mm. Subsequently, the coating apparatus 2 of FIG. 1 was used as the coating apparatus 206, and the coating liquid 2 was applied to the lower surface of this resin film traveling at a speed of 40 m / min. Subsequently, in the transverse stretching machine 204, the resin film coated with the coating liquid 2 is introduced into a 90 ° C. oven and heated, and then the coating liquid 2 is dried in the 100 ° C. oven, and the resin film is moved in the width direction. The resin film was heat-set while being stretched 3.7 times and further subjected to a relaxation treatment of 5% in the width direction in an oven at 220 ° C. to obtain a biaxially stretched film in which a film of the coating liquid 2 was formed on one side. The tension between the longitudinal stretching machine 203 and the lateral stretching machine 204 was controlled by a dancer roll so that the tension per unit width in the running direction of the resin film was 8000 N / m.

  Coating liquid 2 is an emulsion of polyester copolymer (containing components: 90 mol% terephthalic acid, 10 mol% 5-sodium sulfoisophthalic acid, 96 mol% ethylene glycol, 3 mol% neopentyl glycol, 1 mol% diethylene glycol) 100 weight 5 parts by weight of melamine crosslinking agent (imino group-type methylated melamine diluted with a mixed solvent of 10% by weight of isopropyl alcohol and 90% by weight of water) and colloidal silica particles having an average particle size of 0.1 μm Was added to 1 part by weight. The viscosity of this coating liquid 2 was 2 mPa · s at a temperature of 25 ° C. This coating solution was supplied to the container 1 at 17 kg / min by a diaphragm pump (manufactured by Takumina Co., Ltd.). The coating liquid inlet was provided at one place and installed at the bottom of the container 1 as shown in FIG. As the coating bar 3, a round bar made of stainless steel having a diameter of 12.7 mm and a length of 1850 mm and a wire having a linear shape of 0.1 mm (Kano Shoji Co., Ltd.) was used. The support 4 was a roller having a diameter of 22 mm and an axial length of 14 mm, and a surface of which a thermoplastic polyurethane elastomer having a hardness of 95 A was applied to a thickness of 2 mm. A total of eight supports 4 were arranged at a pitch of 470 mm in the longitudinal direction of the coating bar 3. In that case, it arranged in the zigzag form on the upstream side and the downstream side of the coating bar with respect to the transport direction of the resin film, and the angles β1 and β2 shown in FIG. The roller is configured to be rotatable in the circumferential direction and restrained in the axial direction and the vertical direction. The coating bar 3 is supported by the support 4 and bearings at both ends so as to be rotatable in the circumferential direction. The coating bar 3 is pressed against the horizontally transported resin film so that the winding angle α is 10 degrees and is driven in the same direction as the transport direction of the resin film. Rotated.

The first gap and the second gap, which are the shortest distances between the upstream upper end 22 and the downstream upper end 23 and the coating bar surface, were 3 mm and 2 mm, respectively. First gap, the leakage of the coating liquid other than the second gap and only the gap between the sides of the container and the coating bar 30 (shown in FIG. 4), the gap 30 cross-sectional area was confirmed in the drawings is 55 mm ² Met. An acrylic plate having a thickness of 1 mm was used as the upstream upper end 22 and the downstream upper end 23, the inclination angles were both 15 degrees, h3 shown in FIG. 3 was 6.9 mm, and h4 was 3.6 mm. The third gap that is the shortest distance between the weir 21 and the coating bar 3 was 1 mm, and the inclination angle γ was 15 degrees. A stainless steel plate having a thickness of 0.5 mm was used as the weir 21 and a single acrylic plate was installed over the entire width in the longitudinal direction of the container as shown in FIG. At this time, when only the coating bar 3, the weir, and the support 4 are viewed from vertically above, the support located on the downstream side of the coating bar 3 with respect to the transport direction of the resin film in the support 4 is the third. It was provided so that it could not be seen directly from outside the gap. That is, the distances 41, 42, and 43 in FIG. 2 were 2 mm, 10 mm, and 245 mm, respectively, and h5 in FIG. 3 (the vertical distance between the downstream support surface and the tip of the weir 21) was 3.3 mm.

In the evaluation method, a resin film stretched to 5735 ± 70 mm with a horizontal stretcher after coating was sampled for a length of 2 m in the transport direction, and this sample was applied by visual observation by applying a three-wavelength fluorescent lamp in a dark room. Defects and streaks were confirmed. The coating loss defect can be confirmed as an elliptical defect (major axis: 1 to 10 mm, minor axis: 0.3 to 3 mm) because spherical bubbles are repelled after being applied to the resin film together with the coating liquid and then laterally stretched. Furthermore, since this portion has a thin coating thickness, it can be confirmed as color unevenness under a three-wavelength fluorescent lamp. A streak-like defect occurs when the liquid pool 32 of FIG. 1 is disturbed in the application portion, and is a linear defect having a thickness of about 5 to 20 mm in the direction of transporting the resin film. Since this part also has a thin coating thickness, it can be confirmed as linear color unevenness under a three-wavelength fluorescent lamp. The number of defects in the sample was counted as the number per sample, and the number per 1 m ² was calculated. The number of streaky defects was counted as the evaluation result by counting the number of samples having a length of 10 mm or more. Of these defects, the smaller the omission defect, the better. However, if it is 5 pieces / m ² or less, it can be shipped as a product. However, even one streak defect cannot be shipped as a product. Furthermore, the state around the container at the time of application was visually observed. In particular, a flashlight was applied to the periphery of the container to visually observe the state of bubble generation. If the diameter is about 0.1 mm, it can be visually confirmed by applying a flashlight.

When coating was performed with this apparatus, generation of bubbles in the container was not observed. Further, the sample after application had no streak-like defects, and the application defect was a small amount of 0.2 pieces / m ² , which was a high quality product that could be shipped as a product.
[Example 2]
When the coating was performed in the same manner as in Example 1 except that the weir 21 was not provided, the liquid level on the downstream side in the transport direction of the resin film (portion corresponding to the liquid level 12 in FIG. 5) pulsated. There were no streak-like defects, and no bubble was visually observed in the container. In the sample after coating, 4 defects / m ^{2 were} found in the coating missing defect, but it was within the allowable range and could be shipped as a product.
[Example 3]
In the installation of the weir 21, when only the coating bar 3, the weir 21 and the support body 4 are viewed from vertically above, the support located on the downstream side of the coating bar 3 with respect to the transport direction of the resin film in the support body 4. Application was performed in the same manner as in Example 1 except that the body was provided so as to be directly visible from other than the third gap. The installation situation of the weir 21 will be described with reference to FIG. FIG. 18 is a top view of the coating apparatus in the present embodiment, which is the same as that of the first embodiment except that the length of the symbol 41 is 3 mm. In this example, the liquid level on the downstream side in the transport direction of the resin film (portion corresponding to the liquid level 12 in FIG. 5) pulsated. The sample after application had no streak-like defects, and no bubble was visually observed in the container. Further, although 2.2 coating defects / m ^{2 were} found, they were within an allowable range and could be shipped as a product.
[Example 4]
Application was performed in the same manner as in Example 1 except that the third gap was 1.1 mm. As a result, the liquid level (portion corresponding to the liquid level 12 in FIG. 5) on the downstream side in the transport direction of the resin film pulsated. The sample after application had no streak-like defects, and no bubble was visually observed in the container. Further, the defect of coating omission was found to be 1.6 pieces / m ² , but it was within the allowable range and could be shipped as a product.
[Comparative Example 1]
Application was performed in the same manner as in Example 1 except that the upper upstream end 22, the downstream upper end 23, and the weir 21 were not provided. As shown in FIG. 8, the liquid level 12 on the downstream side in the transport direction of the resin film. Dropped to the contact portion 16 between the coating bar and the support, and a large amount of bubbles were generated in the container. Although the discharge rate of the pump was increased to 35 kg / min, the liquid level 12 could not be prevented from falling. Although there were no streak-like defects in the sample after coating, 19 defects / m ^{2 were} found as coating missing defects, and it was impossible to ship as a product.
[Comparative Example 2]
When coating was performed in the same manner as in Example 1 except that the first gap was set to 4 mm, as in Comparative Example 1, the liquid level 12 descended to the contact portion between the coating bar and the support, and a large amount was formed in the container. Bubbles were generated. However, by increasing the pump discharge rate to 20 kg / min, the liquid level 12 could be raised to the tip position of the upper end on the downstream side. At this time, the generation of bubbles in the container was not observed, and the coating missing defect was as small as 0.4 pieces / m ^{2 in} the sample after coating. However, seven streak-like defects thought to have occurred due to shaking of the liquid pool (32 portion shown in FIG. 1) formed on the upstream side of the coating bar were confirmed in the sample after coating, and it was impossible to ship as a product. there were.
[Comparative Example 3]
Application was performed in the same manner as in Example 1 except that the inclination angle of the upstream upper end portion 22 was set to 8 degrees. Bubbles were not generated in the container, and there were only a small amount of defects of 0.5 / m ^{2 in} the sample after coating. However, since the coating liquid leaked from the first gap stayed on the upper surface of the upper end on the upstream side and contacted the resin film, eight streaky defects were confirmed in the coated sample, so that the product could not be shipped. By reducing the discharge rate of the pump, it was possible to avoid contact between the coating liquid and the film remaining on the upper surface of the upper end on the upstream side. However, if the discharge rate of the pump was reduced, the liquid level 12 descended and a large amount in the container Because of the generation of bubbles, the pump discharge rate adjustment was abandoned.
[Comparative Example 4]
Application was performed in the same manner as in Example 1 except that the second gap was set to 3 mm. As in Comparative Example 1, the liquid level 12 descended to the contact portion between the coating bar 3 and the support 4, and the inside of the container A lot of bubbles were generated. However, by increasing the pump discharge rate to 22 kg / min, the liquid level 12 could be raised to the tip position at the upper end on the downstream side. At this time, the generation of bubbles in the container was not observed, and there was only a small amount of defects of 0.6 / m ^{2 in} the sample after coating. However, since the coating liquid leaked from the second gap contacted the coating surface and eight streaky defects were confirmed in the sample after coating, it was impossible to ship as a product.
[Comparative Example 5]
Coating was performed in the same manner as in Example 1 except that the inclination angle of the downstream upper end 23 was set to 8 degrees. No bubble generation was observed in the container, and the coating missing defect was within an allowable range of 0.3 / m ^{2 in} the sample after coating. However, since the coating liquid leaked from the first gap stayed on the upper surface of the upper end portion on the downstream side and contacted the coating surface, four streaky defects were generated, so that the product could not be shipped. By reducing the discharge rate of the pump, it was possible to avoid contact between the coating liquid and the film remaining on the upper surface of the upper end on the upstream side. However, if the discharge rate of the pump was reduced, the liquid level 12 descended and a large amount in the container Because of the generation of bubbles, the pump discharge rate adjustment was abandoned.
[Summary]
The above Examples and Comparative Examples are summarized in Table 1. In Example 1, the upper end 22 on the upstream side, the upper end 23 on the downstream side, and the weir 21 were provided as defined in the claims, and a high-quality sample that could be shipped as a product could be obtained. Examples 2 to 4 are test results when the weir 21 is not used or the installation position deviates from the range specified in the claims, and the sample is of quality that can be shipped as a product, but the number of coating omission defects Since there are more than Example 1, it can be said that it is more preferable to install the weir 21 in the position prescribed | regulated by the claim. Comparative Example 1 is a test result in the case where the upstream upper end portion 22, the downstream upper end portion 23, and the weir 21 are not provided. Since the sample has many disadvantages and cannot be shipped as a product, it can be said that it is important to install each upper end and the weir. Comparative Examples 2 to 5 are test results in the case where the installation positions of the upstream upper end 22 and the downstream upper end 23 deviate from the range specified in the claims. Although an attempt was made to prevent biting, a streak-like defect occurred. Therefore, it can be said that it is important to install the upstream upper end 22 and the downstream upper end 23 at the positions specified in the claims.

  The present invention can be applied not only to the rod coating method but also to any coating method such as a roll coating method, but the application range is not limited thereto.

It is a schematic sectional drawing of embodiment of this invention. It is the top view which looked at FIG. 1 from the Z direction. It is an enlarged view of FIG. It is the side view which looked at FIG. 2 from the W direction. FIG. 2 is an enlarged view of the vicinity of a coating bar when coating is performed with the coating apparatus of FIG. 1. It is a schematic sectional drawing of the coating device which apply | coats a coating liquid using the coating bar to the web continuously conveyed using the technique of patent document 3. FIG. It is an enlarged view of the coating bar vicinity at the time of apply | coating with the apparatus of FIG. It is an enlarged view of the coating bar vicinity at the time of apply | coating with the apparatus of FIG. It is the schematic which showed one form of the manufacturing process of a web. It is the schematic which showed the process at the time of apply | coating in-line during the manufacturing process of the web of FIG. It is the schematic sectional drawing which showed another embodiment of this invention. It is the schematic sectional drawing which showed another embodiment of this invention. It is the schematic which showed the conventional application | coating technique. It is the schematic which showed the conventional application | coating technique. It is the schematic which showed the conventional application | coating technique. It is the schematic which showed the conventional application | coating technique. It is the schematic of the coating bar surface. 6 is a top view of a coating apparatus in Comparative Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 2 Coating liquid 3 Coating bar 4 Support body 5 Rotating roller 6 Conveying roller 7 Substrate 8 Web 11 Accompanying flow 12 Liquid surface 13 Contact point of liquid surface and coating bar 14 Bubble 15 Disappearance defect 16 Contact point 17 Rod 18 Wire 20, 20a, 20c, 20d Supply port 20b Discharge port 21 Weir 22 Upstream upper end 23 Downstream upper end 24 First gap 25 Second gap 26 Third gap 30 Container side and coating Clearance 32 with a working bar Puddle 35 Support body 36 having a V-shaped cross section Roll 37 Plate 38 Pickup roll 39 Partition weir 40 Air bubble 41 Distance between support body and weir 42 Distance between support body and weir 43 Support body Distance to weir 3-1 Coating liquid adhesion bar 3-2 Weighing bar α Winding angle β Support body installation angle γ Weir inclination angle h1 Vertical distance h2 between the support surface on the downstream side and the web Upstream ~ side Vertical distance h3 between the support surface and the web Vertical distance h4 between the downstream support surface and the downstream upper end tip Vertical distance h5 between the downstream upper end tip and the web Vertical support Vertical distance a between body surface and tip of weir 21 Contact point between web and coating bar A Section B Section C Section

Claims (8)

A container having a coating liquid inlet, an upstream upper end and a downstream upper end forming an opening having a longitudinal direction in the longitudinal direction of the container in the upper part of the container, and the upstream upper end in the opening A rotatable coating bar that is provided so as to be sandwiched between the lower end on the downstream side and arranged in the longitudinal direction of the opening with the rotation axis direction, and intermittently along the longitudinal direction of the coating bar A plurality of coating devices that are arranged and have a rotatable support body that supports the coating bar from below in the container, and supply the coating liquid to the container from the coating liquid introduction port. A coating method in which a coating bar is immersed, the coating bar is pressed against the web transported from the upstream side to the downstream side at a predetermined speed, and the coating liquid scooped up by the coating bar is applied to the web. And each upper end has a small upper surface of each upper end. At least a part is inclined downward from the horizontal direction by 10 ° or more and 90 ° or less as the distance from the opening side to the upstream direction and the downstream direction, and among each gap between the coating bar, The first gap located on the upstream side is 3 mm or less, the second gap located on the downstream side is 2 mm or less, and the supply of the coating liquid to the container The coating method, wherein the coating liquid is leaked to the upper surface of each upper end portion from between the coating bar. Provided in the container in a state of being immersed in the coating liquid on the downstream side of the coating bar, and an accompanying flow generated by the rotation of the coating bar and the support flows toward the second gap. The coating method according to claim 1, wherein a weir member is used to suppress damaging. As the weir member, a member having a third gap, which is a gap between the weir member and the outer peripheral surface of the coating bar, having an end extending in the longitudinal direction of the coating bar with a length of 1 mm or less, and each upper end is used. When the coating bar, the weir, and the support are viewed from above in a state without the part, the web, and the coating liquid, the vertical surface of the support that passes through the rotation axis of the coating bar 3. The coating method according to claim 1, wherein a coating having a rotating shaft on the dam side is provided so as not to be directly visible from a portion other than the third gap. The said support body arrange | positions the thing whose length of the axial direction of this support body is 3-25 mm in zigzag form along the longitudinal direction of a coating bar, In any one of Claims 1-3 characterized by the above-mentioned. The coating method as described. A container having a coating introduction port; an upstream upper end and a downstream upper end forming an opening having a longitudinal direction in the longitudinal direction of the container at the upper part of the container; the upstream upper end at the opening; and A rotatable coating bar provided so as to be sandwiched between the upper end portion on the downstream side and arranged in the longitudinal direction of the opening with a rotation axis direction, and a plurality of intermittently along the longitudinal direction of the coating bar A rotatable support that is disposed and supports the coating bar from below in the container; and between the opening and the coating bar, the coating liquid leaks to the upper surface of each upper end. A coating liquid supply means for supplying a coating liquid into the container, the coating bar being pressed against the web conveyed from the upstream side to the downstream side at a predetermined speed, and the coating bar scooped up with the coating bar An application device for applying the coating liquid to the web, wherein Each upper surface is inclined by 10 ° or more and 90 ° or less downward from the horizontal direction as at least a part of the upper surface of each upper end is separated in the upstream direction and the downstream direction from the opening side, and A coating apparatus characterized in that, among the gaps, the first gap located on the upstream side is 3 mm or less, and the second gap located on the downstream side is 2 mm or less. Provided in the container in a state of being immersed in the coating liquid on the downstream side of the coating bar, and an accompanying flow generated by the rotation of the coating bar and the support flows toward the second gap. The coating apparatus according to claim 5, further comprising a weir member for suppressing damaging. The weir member has an end extending in the longitudinal direction of the coating bar with a third gap of 1 mm or less from the outer peripheral surface of the coating bar, and each upper end, the web, and the coating When the coating bar, the weir, and the support body are viewed from vertically above in the absence of liquid, the support body rotates toward the weir side with respect to the vertical plane passing through the rotation axis of the coating bar. 7. The coating apparatus according to claim 5, wherein the shaft is provided so as not to be directly visible from a portion other than the third gap. The length in the axial direction of the support is 3 to 25 mm, and is arranged in a staggered manner along the longitudinal direction of the coating bar. Coating device.

Images