Patent ID: 12214374

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings.

[First Coating Apparatus and Coating Method]

The apparatus configuration of a first coating apparatus will be described.FIG.1is a schematic cross-sectional view of the first coating apparatus,FIG.2is a top view of the coating apparatus inFIG.1viewed from a Z direction,FIG.3is an enlarged view of an area in the vicinity of a coating bar in the coating apparatus ofFIG.1, andFIG.4is a side view of the coating apparatus inFIG.2viewed from a W direction. In these drawings, the longitudinal direction of a container31is determined to be a Y direction, the direction orthogonal to this Y direction is determined to be an X direction, and the direction orthogonal to the X direction and Y direction is determined to be a Z direction. The X direction corresponds to the conveying direction in which a web8is conveyed and the Z direction corresponds to the vertical direction of the coating apparatus.

FIG.1is referred. The first coating apparatus includes a container31for accumulating a coating liquid, a coating bar1immersed in a coating liquid32, and rotatable supports2for supporting the coating bar1from below. Supports2are composed of upstream side supports2a(hereinafter, may simply referred to as “supports2a”) having an axis center13aon the upstream side in the conveying direction of the web8with respect to an axis center12of the coating bar1and supporting the coating bar from below on the upstream side and upstream side supports2b(hereinafter, may simply referred to as “supports2b”) having an axis center13bon the downstream side in the conveying direction of the web8with respect to the axis center12of the coating bar1and supporting the coating bar from below on the downstream side. At the upper part of the container31, an upstream side cover33located on the upstream side of the web8in the conveying direction (illustrated by an arrow at the end of the web8inFIG.1) with respect to the coating bar1and a downstream side cover34located on the downstream side exist. The upstream side cover33and the downstream side cover34form an opening part extending in the longitudinal direction of the container31(in this embodiment, in the Y direction of the coordinate axis illustrated inFIG.2). The coating bar1is arranged in the opening part so that the direction of the rotation axis directs the longitudinal direction of the opening part. The coating bar1is arranged with a clearance35from the downstream side end of the upstream side cover33and arranged with a clearance36from the upstream side end of the downstream side cover34.

FIG.2is referred. The coating bar1is freely and rotatably supported at both ends by bearings or other means (not illustrated). In addition, the coating bar1is supported in a circumscribed manner from below by respective plurality of rotatable supports2aand2bintermittently arranged along the longitudinal direction of the coating bar1. The coating bar1is pressed to the web8conveyed from the upstream side to the downstream side at a predetermined speed to drivenly rotate and the supports2aand2bsupporting the coating bar1also drivenly rotate by the coating bar1.

FIGS.1and4are referred. The flow of the coating liquid in the first coating apparatus will be described. The coating liquid32is continuously supplied from a coating liquid inlet30by a coating liquid supply unit (not illustrated) to be filled in the container. A part of the coating liquid32is applied to the web8by being scraped up by the coating bar1. The remaining coating liquid32continuously leaks out of the container through the clearance35between the surface of the coating bar1and the downstream side end of the upstream side cover33, the clearance36between the surface of the coating bar1and the upstream side end of the downstream side cover34, and a clearance38between the side surface of the container31and the coating bar1(illustrated inFIG.4by diagonal lines).

Gear pumps, diaphragm pumps, and mohno pumps having a quantitative property and a low pulsation property are preferable as the coating liquid supply unit. In addition, the coating liquid discharged from the pump may be supplied to the container through a filter or a defoaming unit. Moreover, the coating liquid may be supplied to the container from several positions of the container.

[Upstream Side Cover and Downstream Side Cover]

FIG.1is referred. The upstream side cover33is preferably at least partially sloped downward from a horizontal level by 10° or more and 90° or less as the upstream side cover33leaves from the opening part side in the upstream side direction. The downstream side cover34is preferably at least partially sloped downward from the horizontal level by at least 10° or more and 90° or less as the downstream side cover34leaves from the opening part side in the downstream side direction. This prevents the coating liquid leaked from the clearance35between the surface of the coating bar1and the downstream side end of the upstream side cover33and the clearance36between the surface of the coating bar1and the upstream side end of the downstream side cover34from accumulating on the upper surface of the upstream side cover33and the downstream side cover34and thus altering the coating liquid and prevents generation of uneven coating due to disturbing a liquid pool39in the upstream side of the coating bar.

FIG.2is referred. As the shape of the upstream side (left side inFIG.2) end of the downstream side cover34, protrusions and recesses are repeatedly formed along the Y direction. Specifically, when a range of a upstream side end15of the downstream side cover34overlapped with the downstream side support2bwhen the downstream side cover34is observed from above in the vertical direction (Z direction) is determined to be an overlapped range14, in the shape of the downstream side cover34, a part at which a clearance from the surface of the coating bar1in a range of the upstream side end15of the downstream side cover34interposed between adjacent overlapped ranges14is wider than a clearance from the surface of the coating bar1at a position in the overlapped range14exists. Here, the term “clearance from the surface of the coating bar” refers to the shortest distance from each point on the upstream side end15of the downstream side cover34to the surface of the coating bar (here, corresponding to the distance in the X direction). In addition, the term “the range of the upstream side end of the downstream side cover overlapped with the downstream side support when the downstream side cover is observed from above in the vertical direction” refers to the range where the upstream side end of the downstream side cover34is overlapped with the supports2bwhen the downstream side cover34is assumed as a transparent product and observed, although, actually, the support2blocated under the downstream side cover34is not visible, if the downstream side cover34is not a transparent product.

The clearance between the surface of the coating bar1and the upstream side end15of the downstream side cover34is narrower within the overlapped range of the support2band the downstream side cover34(overlapped range14) and thus fluctuations in the liquid surface due to the accompanying flow of the supports2bduring high-speed coating can be prevented. As a result, adhering the coating liquid32to the web8and entering air bubbles in the coating area can be prevented and thus coating defects being caused by the air bubbles can be reduced. In addition, even in the case where the air bubbles are mixed in the coating liquid32filled in the coating apparatus, a part having a wider clearance within a range where the support2band the downstream side cover34are not overlapped exists, whereby the air bubbles can be discharged from this part. Consequently, the air bubbles being taken by the coating bar can be prevented and thus coating defects being caused by the air bubbles can be reduced.

The clearance in the range interposed between the adjacent overlapped ranges14may be wider within all of this range or may be wider in some parts of this range as long as the air bubbles can be discharged.

Any methods can be used as the method in which the clearance between the surface of the coating bar1and the upstream side end15of the downstream side cover34is narrowed or widened. Examples of the method include a method in which a cut is formed within the range where the upstream side end15is interposed between the adjacent overlapped ranges14, a method in which the shape of the entire upstream side end15is corrugated, and a method in which a different member is attached to the overlapped range14of the upstream side end15.

FIG.3is referred. With respect to the downstream side cover34, a height L2located on the lowest position in the upstream side end15of the downstream side cover34is arranged at a higher position in the vertical direction than a height L1located on the highest position A in the vertical direction of the supports2(2b) along the longitudinal direction of the container31. When the upstream side end15is located at a position higher in the vertical direction than the highest position L1of the supports2in the vertical direction, the height of the downstream side liquid surface41is higher than the highest position L1of the supports2in the vertical direction, resulting in being less likely to enter the air bubbles by the rotation of the supports2. [Coating Bar]

As the coating bar1, for example, a rod, a wire bar having grooves formed by winding wires around the outer circumferential surface of a rod, and a rolled rod having grooves formed by a rolling process on the outer circumferential surface of a rod can be used. The material of the coating bar1is preferably stainless steel and, in particular, SUS304 or SUS316 are preferable. The surface of the coating bar1may be subjected to a surface treatment such as hard chrome plating. For example, the diameter of the coating bar1is preferably 5 mm to 20 mm because a coating bar having a large diameter tends to cause stripe-like coating defects along the conveying direction referred to as ribbing, whereas a coating bar having a small diameter increases the deflection of the coating bar1. In addition, in this embodiment, the coating bar1is pressed to the web8and rotated by frictional force with the web8, which is in a state of what is called driven rotation. The coating bar1, however, may also be rotated by a driving device such as a motor. In the case where the coating bar1is rotated by the driving device, the coating bar1is preferably rotated in the conveying direction of the web8at substantially almost the same speed as the conveying speed of the web8in order to prevent scratch being caused on the web8. Here, the term “substantially almost the same speed” means that rotation is performed so that the speed difference between the peripheral speed of the coating bar1and the conveying speed of the web8is within ±10%. However, in the case where the scratches on the web do no matter depending on product applications or the like, the coating bar1may be rotated at a speed different from the conveying speed of the web8. In addition, with respect to the winding angle α to the coating bar1illustrated inFIG.1, the web8may flap or vibrate and thus traverse coating defects may be caused when the winding angle α is excessively small, whereas the load on the coating bar1and the supports2may increase and thus the deflection of the coating bar1may increase and the supports2may be abraded when the winding angle α is excessively large. Therefore, the winding angle α is preferably set to a range between 2 degrees to 30 degrees.

[Support]

The supports2may be any supports such as a roller and a ball that support the coating bar1while rotating. In order to reduce the abrasion of the coating bar1, a material having lower hardness than that of the coating bar1is preferably used on the surface layer in the supports2. As the material for the surface layer, a synthetic rubber or an elastomer is preferably used. Here, the elastomer refers to a rubber-like elastic resin that can be melt-molded by, for example, injection molding, extrusion molding, cast molding, blow molding, or inflation molding. As the elastomer, for example, a urethane elastomer, a polyester elastomer, and a polyamide elastomer are preferable. In particular, a thermoplastic polyurethane elastomer having excellent abrasion resistance and mechanical strength is preferably used. The thickness of the elastomer molded onto the surface layer of the supports2is preferably 0.5 mm to 6 mm. The hardness of the elastomer is preferably 60 A to 98 A (measured in accordance with the standard of JIS K6253, 1796).

In order to stably hold the coating bar1, the supports2are preferably placed on both sides of the upstream side and the downstream side of the coating bar1to the conveying direction of the web8as this embodiment. In addition, in order to avoid interference of facing supports2, the supports2may be arranged so as to be slightly shifted in the longitudinal direction of the coating bar1. When an angle determined by a line connecting the axis center13aof the support2aarranged upstream side of the coating bar1to the conveying direction of the web8and the axis center12of the coating bar1with the vertical direction is determined to be β1(illustrated inFIG.1) and an angle determined by a line connecting the axis center13bof support2barranged upstream side of the coating bar1to the conveying direction the web8and the axis center12of the coating bar1with the vertical direction is determined to be β2(illustrated inFIG.1), both of the angles β1and β2are preferably 10 degrees or more. Excessively small angles β1and β2may cause coating defects due to the vibration of the coating bar1caused by the vibration of the web8.

Uneven rotation or vibration of the supports2is likely to cause coating defects by transmitting the rotation or vibration to the coating bar1and thus the supports2preferably have a structure including bearings for smooth rotation. The supports2are submerged in the coating liquid and thus, as the material of the bearing, a material having high corrosion resistance to the coating liquid is preferable and a material having a waterproof property is more preferable. The diameter of the supports2is preferably 8 mm or more because commercially available bearings can be used. The length in the axis direction of the supports2is preferably 3 mm to 25 mm because general-purpose bearings can be used in order to reduce the generated accompanying flow.

The arrangement clearance between the supports2arranged along the longitudinal direction of the coating bar1is preferably narrow because an excessively wide arrangement clearance causes deflection of the coating bar1to be large. As a target, the coating bar1is preferably arranged so that the deflection of the coating bar1is 10 μm or less. The amount of deflection may be determined from the formula of material mechanics using the secondary moment of the cross section and Young's modulus of the coating bar1when the tension applied to the web8in the running direction and the reaction force to the out-of-plane direction of the web8calculated from the winding angle α of the web8to the coating bar1are determined to be the equal distribution load on the coating bar1and the supports2are determined to be the support points.

Examples of the materials for the supports2include metals such as iron, stainless steel, aluminum, and copper; synthetic resins such as nylon, an acrylic resin, a vinyl chloride resin, and tetrafluoroethylene; and rubbers. The shape may be either a plate shape or a block shape.

[Coating Liquid]

The viscosity of the coating liquid is preferably 0.1 Pa s or less. In the case where the viscosity of the coating liquid is high, the coating liquid may become stripe-like form when the coating bar1rakes up the coating liquid in the container and the uniform coating cannot be performed in the width direction of the web. Consequently, stripe-like coating defects may be caused. In this embodiment, the viscosity of the coating liquid is measured in accordance with the standard of JIS Z8803, 1796. For example, a rheometer (RC20, manufactured by RHEOTECH) may be used as a measuring apparatus. Ideally, in measuring the viscosity, the temperature of the coating liquid, which is the measurement condition, is determined to be the temperature of the coating liquid at the actual coating part. However, it is difficult to accurately know the temperature of the coating liquid at the coating part. Therefore, the temperature of the coating liquid may be substituted by a coating liquid temperature in a coating liquid supply unit (not illustrated) such as a feeding tank. The peripheral rotation speed of the coating bar1is preferably 300 m/minute or less. A high peripheral rotation speed tends to cause stripe-like coating defects.

The amount of the coating liquid to be applied is preferably be 2 g/m2to 100 g/m2and more preferably 4 g/m2to 50 g/m2in a wet state immediately after the coating. The amount to be applied can be adjusted by the size of the grooves formed on the coating bar. The groove size can be changed by changing the wire diameter of the wire to be wound in the case where the coating bar is a wire bar or by performing a rolling process with dies having different groove depths and/or groove pitches in the case where the coating bar is a rolled rod.

[Second Coating Apparatus]

The apparatus configuration of a second coating apparatus will be described.FIG.5is a schematic top view of the second coating apparatus andFIG.6is an enlarged view of an area in the vicinity of a coating bar of the coating apparatus inFIG.5. The second coating apparatus has a downstream side cover34A in place of the downstream side cover34of the first coating apparatus. The second coating apparatus has the same apparatus configuration as the apparatus configuration of the first coating apparatus except the downstream side cover34A and thus description other than the downstream side cover34A will be omitted.

FIG.5is referred. When a region of the downstream side cover34A overlapped with the downstream side support2bwhen the downstream side cover34A is observed from above in the vertical direction is determined to be an overlapped region16, in the downstream side cover34A, openings17are formed at a position adjacent to the overlapped region16in the Y direction. For example, in the downstream side cover34A, the openings17are formed in the region interposed between the adjacent overlapped regions16. In the first coating apparatus, the part having a wider clearance between the surface of the coating bar1and the upstream side end15of the downstream side cover34exists within the range where the support2band the downstream side cover34do not overlap. The openings17exhibit the same effect as this part having the wider clearance. In other words, even when the air bubbles are mixed in the coating liquid32filled in the coating apparatus, the air bubbles can be discharged through the openings17and thus the air bubbles being taken by the coating bar can be prevented and coating defects being caused by the air bubbles can be reduced.

As long as the air bubbles can be discharged, the shape of the openings17may be any shapes of a circular shape, a rectangular shape, an oval shape, or the like and the size and number of the openings are not particularly limited.

FIG.6is referred. With respect to the openings17formed in the downstream side cover34A, a height L3at the lowest position of respective edges in the vertical direction is preferably higher in the vertical direction than the height L1at the highest position of the supports2in the vertical direction. When each edge of the openings17is located at a higher position in the vertical direction than the highest position L1of the supports2in the vertical direction, the height of the downstream side liquid surface41is higher than the highest position L1of the supports2in the vertical direction and thus the air bubbles are difficult to be trapped by the rotation of the supports2.

[Third Coating Apparatus]

The apparatus configuration of a third coating apparatus will be described.FIG.7is an enlarged view of an area in the vicinity of a coating bar of the third coating apparatus andFIG.8is a top view of the coating apparatus ofFIG.7from the Z direction. The third coating apparatus further includes an in-liquid cover18with respect to the first coating apparatus. The third coating apparatus has the same apparatus configuration as the apparatus configuration of the first coating apparatus except the in-liquid cover18and thus description other than the in-liquid cover18will be omitted. In the third coating apparatus, the downstream side cover34may have any shape.

FIG.7is referred. The third coating apparatus include an in-liquid cover18between the downstream side cover34and the downstream side support2bin the container31.

FIG.8is referred. The shape of the upstream side (left side ofFIG.8) end of the in-liquid cover18forms a shape in which protrusions and recesses are repeated along the Y direction. Specifically, when the range of the upstream side end of the in-liquid cover18overlapped with the downstream side support2bwhen the in-liquid cover18is observed from above in the vertical direction is determined to be an overlapped range19, in the shape of the in-liquid cover18, a part at which a clearance from the surface of the coating bar1in a range of an upstream side end20of the in-liquid cover18interposed between the adjacent overlapped ranges19is wider than a clearance from the surface of the coating bar1at a position in the overlapped range19exists. Here, the term “clearance from the surface of the coating bar” refers to the shortest distance from each point on the upstream side end20of the in-liquid cover18to the surface of the coating bar. The term “the range of the upstream side end of the in-liquid cover overlapped with the downstream side support when the in-liquid cover18is observed from above in the vertical direction” refers to the range where the in-liquid cover18is overlapped with the support2bwhen both of the downstream side cover34and the in-liquid cover18are assumed as transparent products and observed, although, actually, the support2blocated under the downstream side cover34are not visible, if both of the downstream side cover34and the in-liquid cover18are not transparent products.

The clearance between the surface of the coating bar1and the upstream side end20of the in-liquid cover18is narrower within the overlapped range of the support2band the in-liquid cover18(overlapped range19) and thus fluctuations in the liquid surface41due to the accompanying flow4of the support2bduring high-speed coating can be prevented. As a result, attaching the coating liquid32to the web and entering the air bubbles6in the coating area can be prevented and thus coating defects being caused by the air bubbles can be reduced. In addition, even in the case where the air bubbles6are mixed in the coating liquid32filled in the coating apparatus, a part having a wider clearance within a range where the support2band the in-liquid cover18are not overlapped exists, whereby the air bubbles can be discharged from this part. Consequently, the air bubbles being taken by the coating bar can be prevented and thus coating defects being caused by the air bubbles can be reduced.

The clearance in the range interposed between the adjacent overlapped ranges19may be wider in all of this range or may be wider in some parts of this range as long as the air bubbles can be discharged.

Any methods can be used as the method in which the clearance between the surface of the coating bar1and the upstream side end20of the in-liquid cover18is narrowed or widened. Examples of the method include a method in which a cut is formed within the range where the upstream side end20is interposed between the adjacent overlapped ranges19, a method in which the shape of the entire upstream side end20is corrugated, and a method in which a different member is attached to the overlapped range19of the upstream side end20.

[Fourth Coating Apparatus]

The apparatus configuration of a fourth coating apparatus will be described.FIG.9is a schematic top view of the fourth coating apparatus. The fourth coating apparatus has an in-liquid cover18A in place of the in-liquid cover18of the third coating apparatus. The fourth coating apparatus has the same apparatus configuration as the apparatus configuration of the third coating apparatus except the in-liquid cover18A and thus description other than the in-liquid cover18A will be omitted.

FIG.9is referred. When a region of the in-liquid cover18A overlapped with the downstream side support2bwhen the in-liquid cover18A is observed from above in the vertical direction is determined to be a overlapped region21, openings22are formed in the in-liquid cover18A within the region interposed between the adjacent overlapped regions21. In the third coating apparatus, a part having a wider clearance between the surface of the coating bar1and the upstream side end20of the in-liquid cover18exists in a range where the support2band the in-liquid cover18are not overlapped. The openings22exhibit the same effect as this part having the wider clearance. In other words, even when the air bubbles are mixed in the coating liquid32filled in the coating apparatus, the air bubbles can be discharged through the openings22and thus the air bubbles being taken by the coating bar can be prevented and the coating defects being caused by the air bubbles can be reduced.

As long as the air bubbles can be discharged, the shape of the openings22may be any shapes of a circular shape, a rectangular shape, an oval shape, or the like and the size and number of the openings are not particularly limited.

EXAMPLE

Subsequently, the above embodiments will be specifically described with reference to Examples. The above embodiments, however, are not necessarily limited to the following Examples.

Example 1

The chips of polyethylene terephthalate (hereinafter abbreviated as PET) having a limiting viscosity (also referred to as an intrinsic viscosity) of 0.62 dl/g (measured at 25° C. in o-chlorophenol in accordance with the standard of JIS K7367, 1796) were sufficiently vacuum-dried at 160° C. The vacuum-dried chips were fed to an extruder and melted at 285° C. The melted polymer was extruded from a T-shape Die into a sheet-shaped product and wound onto a mirror-finished cast drum having a surface temperature of 23° C. using an electrostatic casting method. The sheet-shaped product was cooled and solidified to form an unstretched film. Subsequently, the unstretched film was heated by a group of rolls heated to 80° C. and stretched 3.2 times using a longitudinal stretching machine in the longitudinal direction while being further heated by an infrared heater. The stretched film was cooled with cooling rolls of which temperature was controlled at 50° C. to prepare a uniaxial stretched resin film. The width of the resin film was 1,700 mm. Subsequently, the lower surface of this resin film running at a speed of 200 m/min was coated with the coating liquid32using the first coating apparatus illustrated inFIGS.1and2as the coating apparatus. Subsequently, in a transverse stretching machine, the resin film coated with the coating liquid32was introduced into an oven at 90° C. to heat. Subsequently, the coating liquid32was dried in an oven at 100° C. and the resin film was stretched 3.7 times in a width direction. Further, heat setting of the resin film was performed while the resin film was being subjected to relaxation treatment at 5% in the width direction in an oven at 220° C. As described above, a biaxially oriented film having a film made of the coating liquid32on one side was obtained. The tension between the longitudinal stretching machine and the transverse stretching machine was controlled by a dancer roll so that the tension per unit width applied in the running direction of the plastic film was 8000 N/m.

As the coating liquid32, a mixed liquid in which 5 parts by mass of a melamine-based cross-linking agent (a solution of imino group-type methylated melamine diluted in a mixed solvent of 10% by mass of isopropyl alcohol and 90% by mass of water) and 1 part by mass of colloidal silica particles having an average particle diameter of 0.1 μm were added to 100 parts by mass of the emulsion of a polyester copolymer (contained components: 90% by mole of terephthalic acid, 10% by mole of sodium 5-sulfoisophthalic acid, 96% by mole of ethylene glycol, 3% by mole of neopentyl glycol, and 1% by mole of diethylene glycol) was prepared. The viscosity of this coating liquid32was 2 mPa·s at 25° C.

This coating liquid was supplied to the container31at 17 kg/minute by a diaphragm pump (manufactured by Takumina Corporation). A coating liquid inlet was arranged at one position and the port was installed in the container31as illustrated inFIGS.1and2. As the coating bar1, a coating bar formed by winding a wire having a wire diameter of 0.1 mm around a stainless steel round bar material having a diameter of 12.7 mm and a length of 1650 mm (manufactured by Kano Trading Co.) was used. The respective supports2aand2bwere rollers having a diameter of 22 mm and a length in an axial direction of 14 mm and a thermoplastic polyurethane elastomer having a hardness of 95 A was applied to the surface in a thickness of 2 mm. Four supports2aand four supports2bwere arranged at an interval of 470 mm in the longitudinal direction of the coating bar1. In this process, the supports2awere arranged on the upstream side of the coating bar and the supports2bwere arranged on the downstream side in a staggered arrangement to the resin film conveying direction.

As the downstream side cover34, the range of the upstream side end15of the downstream side cover34overlapped with the supports2bwhen the downstream side cover34is observed from above in the vertical direction was determined to be the overlapped range14and the clearance between the upstream side end15of the downstream side cover34and the surface of the coating bar1was set to 0.5 mm in the overlapped range and was set to 1.0 mm in a range interposed between the adjacent overlapped ranges.

As the evaluation method, a transparent polycarbonate downstream side cover was used and the liquid surface41on the downstream side in the conveying direction of the resin film was observed during application. Whether the air bubbles were retained and accumulated was visually checked and the pulsation height of the liquid surface was measured.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side in the conveying direction of the resin film was 5 mm and no attachment to the film was observed. In addition, an aspect that the air bubbles were discharged from the clearance from the surface of the coating bar1in the range interposed between the adjacent overlapped ranges14and were not accumulated inside the container was capable of being observed.

Example 2

Coating was performed in the same manner as the manner in Example 1 except that the second coating apparatus having a downstream side cover illustrated inFIG.5was used. As the downstream side cover34, a cover in which a region of the downstream side cover overlapped with the support2when the downstream side cover34is observed from above in the vertical direction was determined to be the overlapped region16and four openings17having a diameter of 2 mm were arranged at an interval of 100 mm within the range interposed between the adjacent overlapped regions16and at a position 5 mm away from the upstream side end of the downstream side cover was used.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side in the conveying direction of the resin film was 5 mm and no attachment to the film was observed. In addition, an aspect that the air bubbles were discharged from the openings17and were not accumulated inside the container was capable of being observed.

Example 3

The coating was performed in the same manner as the manner in Example 1 except that the third coating apparatus including the in-liquid cover18illustrated inFIGS.7and8and the downstream side cover that was uniform in entire width and had a plate-like shape was used. As the in-liquid cover18, a cover in which a range of the upstream side end of the in-liquid cover18cover overlapped with the support2was determined to be the overlapped range19and the clearance from the surface of the coating bar1was set to 0.5 mm within the overlapped range and was set to 1.0 mm within a range interposed between the adjacent overlapped ranges. The clearance between the surface of the coating bar1and the upstream side end of the downstream side cover was set to 3.0 mm. The in-liquid cover18was made by using a stainless steel plate having a thickness of 1 mm and installed so that the stainless steel plate extended over the entire longitudinal width of the container.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side in the conveying direction of the resin film was 0.5 mm and no attachment to the film was observed. In addition, an aspect that the air bubbles were discharged from the clearance from the coating bar and were not accumulated inside the container was capable of being observed.

Example 4

The coating was performed in the same manner as the manner in Example 1 except that the fourth coating apparatus including the in-liquid cover18illustrated inFIG.9and the downstream side cover that was uniform in entire width and had a plate-like shape was used. As the in-liquid cover18, a cover in which a region of the in-liquid cover overlapped with the support2when the in-liquid cover18was observed from above in the vertical direction was determined to be the overlapped region21and four holes having a diameter of 2 mm were arranged at an interval of 100 mm within the range between the adjacent overlapped regions21and at a position 5 mm away from the upstream side end of the in-liquid cover18was used. The clearance between the surface of the coating bar1and the upstream side end of the downstream side cover was set to 3.0 mm. The in-liquid cover18was made by using a stainless steel plate having a thickness of 1 mm and installed so that the stainless steel plate extended over the entire longitudinal width of the container.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side in the conveying direction of the resin film was 0.5 mm and no attachment to the film was observed. In addition, an aspect that the air bubbles were discharged from the openings22and were not accumulated inside the container was capable of being observed.

Comparative Example 1

The coating was performed at 200 m/minute in the same manner as the manner in Example 1 except that an elastic blade disclosed in Patent Literature 3 was installed as illustrated inFIG.10and the downstream side cover34was replaced with the downstream side cover that was uniform in entire width and had a plate-like shape. With respect to the elastic blade11, a polyethylene film having a thickness of 0.1 mm was used. The elastic blade11was installed so as to fix one end to the lower surface of the downstream side upper end and to protrude from the tip of the downstream side upper end to the coating bar1side. The length of the protruding part (the length in the direction perpendicular to the longitudinal method of the coating bar) was set to 3 mm. The end of the elastic blade on the coating bar side is pressed to the coating bar1so as to contact the upper surface side of the elastic blade to the coating bar1, as illustrated inFIG.10. The length of the elastic blade in the film width direction was set to the same as the inner dimension of the container in the film width direction and the elastic blade was installed so as to extend over the entire width of the container.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side of the resin film in the conveying direction could not be measured because the clearance between the surface of the coating bar1and the downstream side cover was blocked. Naturally, there was no attachment to the film. However, an aspect that air bubbles were accumulated and bubbling occurred in the downstream side cover was observed.

Comparative Example 2

The coating was performed at 200 m/minute in the same manner as the manner in Example 1 except that the weir disclosed in Patent Literature 4 was installed as illustrated inFIG.12and the downstream side cover34was replaced with the downstream side cover that was uniform in entire width and had a plate-like shape. The clearance between the coating bar1and the tip of the weir3was set to 0.5 mm, the inclination angle of the weir3to the horizontal line was set to 15 degrees, and the minimum distance between the outer circumferential surface of the supports2and the weir3surface was set to 3 mm. The weir3was made by using a stainless steel plate having a thickness of 1 mm and installed so that the stainless steel plate extended over the entire longitudinal width of the container.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side of the resin film in the conveying direction was 0.5 mm and no attachment to the film existed. However, an aspect that air bubbles were accumulated and bubbling occurred in the downstream side cover was observed.

Comparative Example 3

The coating was performed at 200 m/minute in the same manner as the manner in Example 1 except that the weir disclosed in Patent Literature 5 was installed as illustrated inFIG.13and the downstream side cover34was replaced with the downstream side cover that was uniform in entire width and had a plate-like shape. As the weir37, a plate made of SUS304 was used. The weir37was installed on the downstream side of the supports2bin the film conveying direction as illustrated inFIG.1so as to form a clearance42of 3 mm. The weir37was installed so that the height of the weir37was the same as the axial center13bof the support2b, as illustrated inFIG.13and installed so as to extend over the entire width of the container in the film width direction.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side of the resin film in the conveying direction was 6 mm and the air bubbles were attached to the resin film to cause coating defects.

Comparative Example 4

The coating was performed at 200 m/minute in the same manner as the manner in Example 1 except that the downstream side cover34was replaced with the downstream side cover that was uniform in entire width and had a plate-like shape. The clearance between the surface of the coating bar1and the upstream side end of the downstream side cover was set to 1.0 mm.

As a result of the coating, the pulsation height of the liquid surface41on the downstream side of the resin film in the conveying direction was 9 mm and the air bubbles were attached to the resin film to cause coating defects.

The coating apparatus and coating method according to the present invention are useful for preventing the air bubbles from trapping and being taken even in high-speed coating and for reducing coating defects being caused by the air bubbles.

REFERENCE SIGNS LIST

1Coating Bar2Supports2aUpstream Side Supports2bDownstream Side Supports3Weir4Accompanying Flow5Accompanying Flow of Coating Bar6Air Bubbles7Contact Point between Coating Bar and Support8Web9Rod10Wire11Elastic Blade12Axis Center of Coating Bar13Axis Center of Support13aAxis Center of Upstream Side Support13bAxis Center of Downstream Side Support14Overlapped Range15Upstream Side End of Downstream Side Cover16Overlapped Region17Openings18,18A In-liquid Cover181First Range of Upstream Side End of In-liquid Cover182Second Range of Upstream Side End of In-liquid Cover18A1First Region of In-liquid Cover18A2Second Region of In-liquid Cover19Overlapped Range20Upstream Side End of In-liquid Cover21Overlapped Region22Openings30Coating Liquid Inlet31Container32Coating Liquid33Upstream Side Cover34,34A Downstream Side Cover341First Range of Upstream Side End of Downstream Side Cover342Second Range of Upstream Side End of Downstream Side Cover34A1First Region of Downstream Side Cover34A2Second Region of Downstream Side Cover35Clearance between Downstream Side End of Upstream Side Cover and Coating Bar Surface36Clearance between Upstream Side End of Downstream Side Cover and Coating Bar Surface37Weir38Clearance between Side Surface of Container and Coating Bar39Liquid Pool40aAccompanying Flow from Lower Part of Supports40bAccompanying Flow from Upper Part of Supports41Liquid Surface42Clearance between weir and supportL1Height of Highest Position of Support in Vertical DirectionL2Height of Upstream Side End of Downstream Side CoverL3Height of Opening Edge of Downstream Side Coverα Winding Angleβ1Installation Angle of Supportβ2Installation Angle of Support