JP6593093B2 - Coating apparatus, coating apparatus, and method for producing coated film web - Google Patents

Description

  The present invention relates to a coating apparatus for simultaneously forming a coating film on both sides of a web, a coating apparatus provided with the coating apparatus, and a method for producing a coated web using the coating apparatus.

  A simultaneous double-side coating method is known as a method for simultaneously forming a coating film on both surfaces of a web, and a coating film is simultaneously formed on both surfaces of a web by a coating device disposed on both sides of the web. Specifically, coating devices such as rolls, knives, and slit dies are arranged on both sides of the web, and a coating film is simultaneously formed on both sides of the web. Which coating apparatus is selected is selected appropriately depending on the viscosity of the coating liquid to be applied and the film thickness accuracy of the target coating film.

  In the double-sided simultaneous coating method, the film thickness uniformity in the coating width direction greatly depends on the processing accuracy and installation accuracy of the coating apparatus itself. In particular, when the viscosity of the coating liquid to be applied is high, the liquid pressure of the coating liquid existing between the web and the coating apparatus is higher than when the viscosity is low. The central portion is spread and a uniform film thickness cannot be obtained in the coating width direction. Therefore, it is also important to increase the rigidity of the coating apparatus itself to suppress deformation.

  As a simultaneous double-side coating method, Patent Document 1 discloses a method of forming a coating film by measuring a coating liquid with a pipe-type doctor facing the coating film so that the coating film thickness becomes a desired film thickness.

  Moreover, as another method of the simultaneous double-side coating method, Patent Document 2 and Patent Document 3 disclose a method of forming a coating film on both surfaces simultaneously with a pair of slit dies facing each other with a web interposed therebetween. In the coating method disclosed in Patent Document 2, a coating liquid supplied from a slit outlet is applied to a web, and a coating film is simultaneously formed on both sides of the web. In addition, the coating method disclosed in Patent Document 3 uses a coating apparatus configured with two surfaces having a gentle slope from the liquid storage unit to the metering unit.

JP-A-10-328596 JP 2011-12266 A European Patent No. 1270133

  However, it is generally difficult to accurately process the straightness in the longitudinal direction with a cylindrical member having no flat surface such as a pipe or a roll used in the coating method disclosed in Patent Document 1. Furthermore, when installing a pair of pipe-type doctors facing each other, it is difficult to adjust the gap in the coating width direction to be constant. As described above, since the film thickness uniformity of the coating film depends on the processing accuracy and installation accuracy of the coating apparatus, the coating method disclosed in Patent Document 1 has a uniform film thickness distribution in the coating width direction. Formation is difficult.

  In the coating method using a slit die disclosed in Patent Document 2, the hydraulic pressure immediately below the slit is increased. This phenomenon becomes more prominent as the viscosity of the coating liquid increases. When a high-viscosity coating liquid is applied, resistance due to the hydraulic pressure is generated in the coating section, and excessive tension is required to transport the web. Will cause wrinkles.

  Even in the coating method disclosed in Patent Document 3, the liquid pressure increases as the coating liquid approaches the web, as in the coating method of Patent Document 2, so that resistance due to the hydraulic pressure is generated in the coating portion, and the rigidity of the web is increased. Depending on the case, wrinkles will occur.

  Therefore, the present invention can apply a coating liquid with a uniform film thickness in the coating width direction on both surfaces of the web, suppress an increase in the hydraulic pressure in the coating liquid measuring section, and can suppress a web conveyance resistance due to the hydraulic pressure. A coating apparatus is provided. Moreover, the coating device provided with the coating device and the manufacturing method of the web with a coating film using the coating device are provided.

The coating apparatus of the present invention that solves the above problems is a coating apparatus for simultaneously coating a coating liquid on both sides of a traveling web,
A liquid storage member serving as a wall surface of a liquid storage section for storing the coating liquid;
A pair of weighing units that are provided opposite to each other with a gap between the web running surface downstream of the liquid storage member in the web running direction and that serve as a bottom surface of the liquid storage unit and form a liquid storage unit together with the liquid storage member A member, and
Coating liquid in contact with a surface of the metering member, consists of three planes that are adjacent so as to approach the running surface of the web, each of these planes is inclined toward the running direction downstream side of the web, each of these planes the inclination angle is the angle formed between the direction perpendicular to the running surface of the web is greater etc. ho plane close to the running surface of the web.

Moreover, it is preferable that the coating device of this invention is the following structures.
The plane closest to the web running surface among the surfaces in contact with the coating liquid is substantially parallel to the web running surface.
The metering member further has a plane adjacent to the plane closest to the traveling surface of the web among the surfaces in contact with the coating liquid on the downstream side in the traveling direction of the web, and the adjacent plane is away from the traveling surface of the web. Thus, it is perpendicular to the traveling surface of the web or is further away from the traveling surface of the web as it goes downstream in the traveling direction of the web.
-It has a means which can move each of a pair of said measuring member to the thickness direction of a web.
The portion of the weighing member that is closest to the web running surface is made of a material different from the other portions.

  Moreover, the coating apparatus of this invention is equipped with the coating device of this invention, and the conveying apparatus which conveys a web.

  Further, the method for producing a web with a coating film according to the present invention uses the coating apparatus according to the present invention to introduce a web into the gap between the pair of measuring members and to store the coating material stored in the liquid storage part in the liquid storage part. The liquid is adhered to both surfaces of the web, and the coating liquid adhered to both surfaces of the web is measured to a predetermined film thickness by adjusting the gap between the pair of metering members to form a coating film on both surfaces of the web.

  If the coating apparatus of this invention is used, the conveyance resistance of the web by a hydraulic pressure can be suppressed by suppressing the raise of the hydraulic pressure of an application part. As a result, coating can be performed without applying excessive tension to the coating portion, and a coating film having a uniform film thickness in the coating width direction can be simultaneously formed on both sides of the web.

It is a schematic sectional drawing of the coating device by one Embodiment of this invention. It is a schematic sectional drawing of the coating device by another embodiment of this invention. It is an enlarged view of the P section of FIG.

  Preferred embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the form shown in the drawings, and various modifications can be made without departing from the gist of the invention and achieving the object of the invention.

  FIG. 1 is a schematic cross-sectional view of a coating liquid coating apparatus 100 of the present invention. The coating apparatus 100 is an apparatus that forms the coating film 2 by applying the coating liquid 1 on both surfaces of the web 0. The coating apparatus 100 includes liquid storage members 101 and 101 'and a pair of measuring members 102 and 102'. The liquid storage members 101 and 101 ′ are the wall surfaces of the liquid storage part X for storing the coating liquid 1. The measuring members 102 and 102 ′ are provided opposite to each other with a space t between the liquid storage members 101 and 101 ′ on the downstream side in the traveling direction of the web 0 with the traveling surface of the web 0 interposed therebetween. The liquid storage part X is formed together with the liquid storage members 101 and 101 ′. Further, in this coating apparatus 100, in order to store the coating liquid 1 in the liquid storage part X, the liquid storage members 101, 101 ′ and the measuring members 102, 102 ′ are sandwiched between the front side and the rear side of the paper in FIG. A side plate (not shown) is provided.

The measuring members 102 and 102 ′ are configured by three adjacent planes 103, 104 and 105 and 103 ′, 104 ′ and 105 ′ so that the surface in contact with the coating liquid 1 approaches the traveling surface of the web 0. . And each plane 103,104,105 (103 ', 104', 105 ') inclines toward the running direction downstream side of the web0. Furthermore, the more the surface closer to the running surface of the web, i.e. towards the plane 103 (103 ') plane 104 (104 than') is, and the better of the plane 104 (104 ') plane 105 (105 than'), each The inclination angles (θ3, θ4, θ5 in FIG. 3), which are angles formed by the planes 103, 104, 105 (103 ′, 104 ′, 105 ′) and the direction perpendicular to the running surface of the web 0, are large. The planes in contact with the coating liquid 1 of the measuring members 102 and 102 ′ are constituted by three or more planes adjacent to each other so as to approach the traveling surface of the web 0 as shown in FIG. In addition, regardless of the number of adjacent planes, each plane is inclined toward the downstream side in the traveling direction of the web 0, and the inclination angle is larger as the plane is closer to the traveling direction of the web 0.

  By using such a pair of measuring members 102, 102 'of the present invention, the coating film 2 having a uniform film thickness in the coating width direction can be obtained. The operation is as follows.

  First, the film thickness uniformity in the coating width direction of the coating film 2 depends on the processing accuracy of the measuring member 102 (102 '). A side 107 (107 ′) shared by the plane 105 (105 ′) and the plane 106 (106 ′) adjacent to the plane 105 (105 ′) on the downstream side in the running direction of the web 0 is a separation point of the coating liquid 1. There is a meniscus on this side 107 (107 '). In order for the meniscus to be stable in the coating width direction, the side 107 (107 ') needs to be processed uniformly in a substantially straight line without distortion in the coating width direction. Since the measuring member 102 (102 ′) is composed of a plurality of planes, it is possible to provide a reference plane when the measuring members 102 and 102 ′ are processed and installed, and to be processed and installed with high accuracy. . As a result, the film thickness in the coating width direction of the coating film 2 can be made uniform.

  In order to reduce the straightness value of the side 107 (107 '), the surface 106 (106') is preferably a flat surface. Since the surface 106 (106 ') can be processed with high accuracy when it is a flat surface, the straightness value of the side 107 (107') can be reduced together with the surface 105 (105 ') being a flat surface. Further, since the processing of the flat surface is easy, the processing cost is low.

  The plane 106 (106 ') is preferably perpendicular to the traveling surface in a direction away from the traveling surface of the web 0, or away from the traveling surface of the web 0 toward the downstream side in the traveling direction of the web 0. That is, it is preferable that the angle (θ in FIG. 3) formed by the flat surface 106 (106 ′) and the running surface of the web 0 at the liquid separation point is 90 degrees or less. If the angle of the liquid separation point is 90 degrees or less, the flat surface 106 (106 ') can be processed with high accuracy, and the straightness value of the side 107 (107') can be reduced.

  When the coating liquid 1 moves between the web 0 and the plane 105 (105 ′) along with the conveyance of the web 0, the coating liquid 1 flows between the web 0 and each plane of the measuring member 102 (102 ′). As the gap t moves toward the closing portion Y, the fluid pressure increases, and a force (hereinafter referred to as coating resistance) that causes a conveyance resistance in a direction opposite to the conveyance direction of the web 0 is generated. For example, in the pipe-type doctor disclosed in Patent Document 1, the hydraulic pressure increases rapidly toward the closing portion. Further, even in a configuration in which the distance between the web and the application member disclosed in Patent Document 2 is uniformly reduced, the increase in the hydraulic pressure is large, and excessive application resistance is generated in the application part. On the other hand, in the measuring member 102 (102 ′) of the present invention, the surface where the three adjacent planes 103, 104, 105 (103 ′, 104 ′, 105 ′) are closer to the traveling surface of the web 0 is downstream in the traveling direction of the web 0. Since the inclination angle toward the surface is large (θ3 <θ4 <θ5), the surface in contact with the coating liquid 1 is gently inclined. Therefore, since the difference between the amount of the coating liquid 1 entering the measuring member 102 (102 ′) and the amount of the coating liquid 1 exiting from the exit of each inclined surface is small, it is possible to suppress an increase in the hydraulic pressure. As a result, the coating resistance can be suppressed. As a result, when the coating liquid 1 is applied to the web 0, it can be applied without applying excessive tension to the web 0. In the coating process on the web 0, after the coating film 2 is formed by the coating apparatus 100, a process such as drying is performed to fix the coating film 2. In particular, in the drying process, when excessive tension is applied to the web 0, the web 0 is curled or eared, or heat wrinkles are generated due to heat applied in the drying process. Therefore, it is necessary to suppress the coating resistance. In order to suppress this coating resistance, it is necessary that the measuring member 102 (102 ') has three or more adjacent planes. If there are only two adjacent planes, the effect of suppressing an increase in hydraulic pressure is not sufficient, and therefore an increase in coating resistance cannot be suppressed.

  The measuring member 102 (102 ′) has a length (L in FIG. 3) of the plane 105 (105 ′) closest to the traveling surface of the web 0 in the web traveling direction due to the workability of the measuring member 102 (102 ′). 1 mm or more is preferable, and considering the ease of adjusting the gap t, it is preferably 5.0 mm or less. The lower limit of the length L in the web traveling direction is more preferably 0.5 mm or more. The upper limit of the length L in the web running direction is more preferably 1.5 mm or less. Considering that the coating resistance is proportional to the length L of the flat surface 105 (105 ′), the pressure of the coating liquid 1 becomes excessive when the high-viscosity coating liquid 1 is applied if it is 1.5 mm or less. And the conveyance resistance of the web 0 can be suppressed. On the other hand, when the length L in the web running direction is 0.5 mm or more, when the low-viscosity coating liquid 1 is applied, the pressure of the coating liquid 1 can be suppressed from being too small, and the liquid pressure is too small. Since the force for pressing the web 0 from both the front and back sides of the web 0 is insufficient due to the hydraulic pressure, it is possible to suppress the wrinkle generated on the web 0 at the coating part Z.

  Since the film thickness of the coating film 2 depends on the distance between the measuring member 102 (102 ′) and the surface of the web 0, the coating apparatus 100 can move the measuring members 102 and 102 ′ in the thickness direction of the web 0 (illustrated). Not). Examples of such means include a moving table on which the weighing members 102 and 102 ′ are placed and can move in the thickness direction of the web 0 together with the weighing members 102 and 102 ′. By providing such a moving means, the film thickness of the coating film 2 can be adjusted with high accuracy and high reproducibility.

  It is preferable that the measuring members 102 and 102 ′ are arranged substantially in parallel to face each other with a gap t across the web 0. When the coating liquid 1 is interposed between the web 0 and the measuring members 102 and 102 ', the hydraulic pressures on both sides of the web 0 are balanced, and the web 0 always exists at the center of the pair of measuring members 102 and 102'. Therefore, the moving means of the measuring member 102 (102 ') is required to have an accuracy with which the measuring members can be installed substantially in parallel.

  The plane 105 (105 ') of the measuring member 102 (102') is preferably substantially parallel to the web 0. Considering that the web 0 exists in the center of the pair of measuring members 102 and 102 ′ when the coating liquid 1 is interposed, if the plane 105 (105 ′) is substantially parallel to the web 0, the film of the coating film 2 There is an effect that thickness adjustment becomes easy. This is because the hydraulic pressure is reduced between the web 0 and the flat surface 105 (105 '), and only a shear flow exists at the side 107 (107') which is a liquid separation point. When only shear flow exists, it is known that the film thickness immediately after the coating part Z is half of the gap t, and therefore the gap t may be adjusted to twice the desired film thickness. Adjustment time can be shortened. Since this is a phenomenon that does not depend on the conveyance speed of the web 0, there is also an effect that coating can be performed in a wide speed range from low speed to high speed. Note that the arrow of the web 0 in FIG. 3 indicates that the web 0 is parallel to the plane 105.

  In addition, when the pair of measuring members 102 and 102 ′ are arranged to face each other with a gap t between the webs 0, the planes 105 and 105 ′ are measured according to the measurement result obtained by measuring the gap t between the opposed planes 105 and 105 ′. The gap t is preferably adjusted to be uniform in the coating width direction. At the time of adjustment, if the pair of measuring members 102 and 102 ′ can move in the thickness direction of the web 0, the same gap t can be adjusted regardless of the operator.

  FIG. 2 is a schematic cross-sectional view of a coating apparatus 200 according to another embodiment of the present invention. The coating device 200 includes a member 208 (208 ′) that is closest to the web 0 and a member 209 (209 ′) that is a different material from the member 208 (208 ′). It is the coating device 200 provided with. An example in which a highly rigid material is selected for the member 208 (208 ') will be described as an example. When the high-viscosity coating liquid 1 is applied, the liquid pressure becomes higher than when the low-viscosity coating liquid 1 is applied. When the hydraulic pressure is high, the force with which the coating liquid 1 pushes the measuring member 202 (202 ′) is increased particularly in the center of the coating width direction where the coating liquid 1 does not escape, and the coating width of the measuring member 202 (202 ′) is increased. The gap t between the measuring member 202 (202 ′) and the web 0 is pushed wide at the center in the direction, and the film thickness of the coating film 2 becomes thick at the center in the coating width direction. By using a highly rigid material for the member 208 (208 '), such a problem can be prevented. Further, an example in which a material having wear resistance is selected for the member 208 (208 ') will be described. When the coating liquid 1 containing particles of high hardness is applied to the coating liquid 1, the shear force of the coating liquid 1 is high at the portion where the web 0 and the measuring member 202 (202 ′) are closest to each other. The measuring member 202 (202 ′) is scraped off by the hardness particles. If the measuring member 202 (202 ′) is shaved, the distance between the web 0 and the measuring member 202 (202 ′) changes over time, resulting in fluctuations in the film thickness or the coating film 2 in the coating width direction. Distribution of the film thickness occurs, or small pieces of the measuring member 208 (208 ′) and wear powder that have been cut off are mixed into the product. Such a problem can be prevented by using a material having wear resistance for the member 208 (208 '). On the other hand, the member 209 (209 ′), which is a constituent member of the measuring member 202 (202 ′), does not require rigidity, wear resistance, and durability as much as the member 208 (208 ′). 208 ′) can be used, and the cost of the measuring member 202 (202 ′) can be reduced. That is, by configuring the weighing member 202 (202 ′) with different materials for the member 208 (208 ′) and the member 209 (209 ′) closest to the web, the rigidity of the weighing member 202 (202 ′) can be reduced. While improving wear resistance and durability, an increase in cost can be suppressed.

  The coating apparatuses 100 and 200 of the present invention can be suitably used as a web coating apparatus that applies the coating liquid 1 while conveying a long web 0. In particular, the web coating apparatus using the coating apparatuses 100 and 200 of the present invention can obtain a uniform coating film 2 regardless of the viscosity of the coating liquid 1 and the conveyance speed of the web 0.

  Moreover, in the manufacturing method of the web with a coating film of this invention, since the same film thickness can be obtained on the front and back of the web with a coating film, the coating film 2 of the same film thickness is simultaneously formed on both surfaces of the web 0. It is suitable for.

<Example 1>
A coating apparatus 100 shown in FIG. 1 was prepared. The surface of the measuring member 102 (102 ′) that is in contact with the coating liquid 1 is composed of three planes 103, 104, 105 (103 ′, 104 ′, 105 ′), and each plane faces the downstream side in the running direction of the web 0. Θ3 = 45 °, θ4 = 70 °, and θ5 = 90 °, and the plane closer to the running surface of the web 0 has a larger inclination angle. Further, the planes 105 and 105 ′ closest to the running surface of the web 0 are substantially parallel to the running surface of the web 0 and the gap t is 50 μm, and the running direction length L of the web 0 on the plane 105 (105 ′) is Each is 1.5 mm. The planes 106 and 106 ′ adjacent to the planes 105 and 105 ′ on the downstream side in the web running direction are planes, and the angle θ formed between the plane 106 (106 ′) and the running plane of the web 0 is 45 degrees. The distance from the traveling surface of the web 0 increases toward the downstream side in the traveling direction. Using the coating apparatus 100, the coating liquid 1 was applied on the web 0 having a thickness of 7 μm. The meniscus at the sides 107 and 107 'at the liquid separation point was stable in the coating width direction. In addition to a good coating surface free of coating defects such as streaks and unevenness, a uniform film thickness could be obtained in the coating width direction.

<Example 2>
The same coating apparatus 100 as in Example 1 was prepared except that the length L in the web running direction of the planes 105 and 105 ′ was 0.3 mm. Using this coating apparatus 100, the coating liquid 1 was coated on the web 0 having a thickness of 7 μm. During application, slight tin-like wrinkles were generated in the vicinity of the application portion Z, but the meniscus at the sides 107 and 107 ′ at the liquid separation point was stable in the application width direction. It was possible to obtain a uniform film thickness in the coating width direction without causing coating defects such as folds and streaks due to tin-like wrinkles.

<Comparative Example 1>
A coating device 100 was prepared in which the shape of the measuring member 102 was a cylinder having a diameter of 25 mm, and the cylinder was substantially parallel to the web 0 in the coating width direction. When the coating liquid 1 was applied using this coating apparatus 100, the meniscus was unstable in the coating width direction and shaped to wave in the coating width direction. Since the meniscus state was not stable, rib-like streaks parallel to the running direction of the web 0 were present at equal intervals in the coating width direction on the coating surface, resulting in coating defects.

0: Web 1: Coating liquid 2: Coating film 100: Coating apparatus 200: Coating apparatus 101, 101 ': Liquid storage member 102, 102': Measuring member 103, 103 ': Coating liquid 1 of measuring member 102 (102') Planes 104 and 104 ′ in contact with the coating liquid 1 of the measuring member 102 (102 ′): planes 105 and 105 ′ in contact with the coating liquid 1 of the measuring member 102 (102 ′) and the plane closest to the web running surface 106, 106 ′: Flat surfaces 107, 107 ′ adjacent to the planes 105, 105 ′ on the downstream side in the web traveling direction: sides shared by the planes 105, 105 ′ and the planes 106, 106 ′ (liquid separation points)
202, 202 ′: Metering members 205, 205 ′ composed of a plurality of members: Planes 208, 208 ′ that are in contact with the coating liquid 1 of the metering members 202, 202 ′ and closest to the traveling surface of the web 0, 208: The metering member 202 , 202 ′, the members 209, 209 ′ closest to the web running surface, the members L constituting the weighing members 202, 202 ′, the web running direction length t of the planes 105, 105 ′, a pair of weighing members 102. And 102 ′: Liquid storage part Y: Blocking part Z: Application part θ: Angle formed between the plane 106 (106 ′) and the running surface of the web 0 θ3: Angle of inclination of the planes 103 and 103 ′ θ4: Plane Inclination angle θ5 of 104, 104 ′: Inclination angle of planes 105, 105 ′

Claims (7)

A coating device for simultaneously applying a coating liquid to both sides of a traveling web,
A liquid storage member serving as a wall surface of a liquid storage section for storing the coating liquid;
A pair of weighing units that are provided opposite to each other with a gap between the web running surface downstream of the liquid storage member in the web running direction and that serve as a bottom surface of the liquid storage unit and form a liquid storage unit together with the liquid storage member A member, and
Coating liquid in contact with a surface of the metering member, consists of three planes that are adjacent so as to approach the running surface of the web, each of these planes is inclined toward the running direction downstream side of the web, each of these planes the inclination angle is the angle formed between the direction perpendicular to the running surface of the web is greater etc. ho plane close to the running surface of the web, the coating apparatus.   The coating apparatus according to claim 1, wherein a plane closest to the traveling surface of the web among the surfaces in contact with the coating liquid is substantially parallel to the traveling surface of the web. The metering member further has a plane that is closest to the traveling surface of the web among the surfaces in contact with the coating liquid and a plane that is adjacent on the downstream side in the traveling direction of the web,
Application according to claim 1 or 2, wherein the adjacent planes are perpendicular to the web running surface in a direction away from the web running surface or away from the web running surface as going downstream in the web running direction. apparatus.   The coating apparatus according to claim 1, further comprising a means capable of moving each of the pair of measuring members in the thickness direction of the web.   The applicator according to any one of claims 1 to 4, wherein the metering member is made of a material different in the portion closest to the web running surface from the other portions.   The coating device provided with the coating device in any one of Claims 1-5, and the conveying apparatus which conveys a web. A web is introduced into the gap between the pair of measuring members using the coating apparatus according to claim 6, and the coating liquid stored in the liquid storage part is adhered to both surfaces of the web in the liquid storage part. A method for producing a web with a coating film, wherein the coating liquid adhered to both surfaces of the web is adjusted to a predetermined film thickness by adjusting the gap to form a coating film on both surfaces of the web.

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