Method for manufacturing a substrate with a coated film and spray coating apparatus

Abstract

To provide a manufacturing method of a base material with coating film which reduces variations in a width direction end of a coating film generated when using a slot type spray nozzle.SOLUTION: A manufacturing method of a base material with coating film according to the present invention is the method of manufacturing a base material with coating film which is formed with a coating film by spraying coating droplets from a nozzle toward a conveyed coating object base material uses a spray nozzle forming the coating droplets by making the air discharged from an air exhaust port collide with coating liquid while discharging the coating liquid from a coating liquid discharge port to make a portion of the air discharged from the air exhaust port blown through a virtual surface that passes through a surface on the opposite side to a surface formed with the coating liquid of the coating object base material on the outer side of both ends in the width direction of the coating object base material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a substrate with a coating film, and a spray coating apparatus used in the manufacturing method.

Background Art

[0002] Conventionally, as a method for manufacturing a substrate with a coating film, a spray coating method in which a coating liquid is atomized into droplets by a spray nozzle (hereinafter also simply referred to as a "nozzle") and then sprayed is known.

[0003] In this spray coating method, generally, from the viewpoints of the productivity and functionality of the substrate to be coated (hereinafter also simply referred to as the "substrate"), it is required to form a coating film with a uniform thickness on substantially the entire surface of a wide-width substrate.

[0004] As a coating method in such a case, for example, in Patent Document 1, a two-fluid type single-hole spray nozzle that discharges squeezing air simultaneously with the coating liquid and atomizes the coating liquid by the discharged air and sprays it is arranged in a plurality of rows at equal intervals in the width direction of the substrate, and the substrate is conveyed while spraying the coating liquid simultaneously so that the coating liquids sprayed from each nozzle overlap each other, thereby forming a coating film on the wide-width substrate. However, in this spray coating method, since each nozzle is an independent component, variations in the spraying state are likely to occur due to individual differences in the nozzles, that is, variations in the shape of each nozzle. Further, since the discharged air and the coating droplets ejected from each nozzle fly while expanding in the width direction in a form such as a fan shape or a conical shape, interference occurs at the overlapping portions of the coating between the nozzles, and coating streaks are likely to occur, making it difficult to form a uniform coating film.

[0005] To address the challenges of such single-hole nozzles, Patent Document 2 discloses a coating method that allows for broad and uniform application of a coating film. This method uses a slot-type spray nozzle having multiple coating liquid discharge ports in the coating width direction of the substrate, and a pair of air discharge ports that open continuously or intermittently in the width direction near the coating liquid discharge ports, flanking the coating liquid discharge ports. Because this spray nozzle is a single nozzle spanning the coating width, variations in the spray state are small, and the coating liquid can be sprayed with extremely high uniformity in the coating width direction. Furthermore, since the discharged air is substantially a band-shaped parallel flow, the coating liquid flies with almost no velocity in the width direction, thus forming a uniform coating film on the substrate.

[0006] On the other hand, even when using such a slot-type spray nozzle, the coating film thickness may vary at both ends of the coating width and around them compared to the center, resulting in an uneven coating film. According to Patent Document 3, this is because the discharged strip of air is in contact with the air at both ends, and is influenced by the air, causing it to be drawn into the flow in the center and resulting in flow contraction. As a solution, the air discharge port width is made up to 150 mm wider on one side than the coating liquid discharge port width, so that the area affected by the flow contraction of the discharged air is outside the coating width and does not affect the formation of the coating film. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-111512 [Patent Document 2] Japanese Patent Publication No. 2006-026576 [Patent Document 3] Japanese Patent Publication No. 2006-205099 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, as a result of the inventors' investigations, it was found that variations in the coating film cannot be completely resolved simply by isolating the area where the coating film is formed from the effect of the compressed discharge air, and that other factors also contribute to these variations.

[0009] The present invention has been made in view of the above problems, and provides a method for manufacturing a substrate with a coating film that reduces variations in the widthwise edges of the coating film that occur when using a slot-type spray nozzle. Furthermore, the present invention provides a spray coating apparatus used in this manufacturing method. [Means for solving the problem]

[0010] The present invention, which solves the above problems, is a method for manufacturing a coated substrate by spraying coating droplets from a nozzle onto a conveyed substrate to be coated, thereby manufacturing a coated substrate in which a coating film has been formed. As the above nozzle, The system includes a coating liquid discharge port that discharges the coating liquid over a width direction intersecting the transport direction of the substrate to be coated, and a pair of air discharge ports that are arranged near the coating liquid discharge port, opening continuously or intermittently over the width direction, and flanking the coating liquid discharge port, to discharge air. A spray nozzle is used that, while discharging the coating liquid from the coating liquid outlet, collides air discharged from the air outlet onto the coating liquid to form coating droplets. A portion of the air discharged from the above-mentioned air outlet blows through a virtual surface that passes on both sides of the width direction of the substrate to be coated, on the side of the substrate to be coated that is opposite to the side on which the coating film is formed.

[0011] The method for manufacturing a substrate with a coated film according to the present invention is preferably as follows. (1) The width of the coating liquid discharge port is smaller than the width of the substrate to be coated. (2) The width of the air blowing through the above-mentioned virtual surface is 10 mm or more on one side.

[0012] One aspect of the spray coating apparatus of the present invention, which solves the above problems, comprises a spray nozzle having a plurality of coating liquid discharge ports arranged in the width direction, and a pair of air discharge ports arranged near the coating liquid discharge ports, opening continuously or intermittently in the width direction to sandwich the coating liquid discharge ports, a supply means for supplying coating liquid and air to the spray nozzle, and a transport means for transporting a substrate to be coated on which a coating film is formed. The above-described transport means transports the coated substrate without supporting the surface of the substrate to be coated that is opposite to the surface on which the coating film is formed, in the range facing the tip of the spray nozzle, or while supporting the surface of the substrate to be coated that is opposite to the surface on which the coating film is formed, within a width that fits within the width of the substrate to be coated. The width of the air outlet is such that the projection image of the air outlet onto the substrate to be coated extends beyond both sides in the width direction of the coated substrate.

[0013] The spray coating apparatus of the present invention in this embodiment is preferably in the following form. (1) The width of the air outlet is 10 mm or more wider on one side than the width of the substrate to be coated. (2) The width of the coating liquid discharge port is smaller than the width of the substrate to be coated.

[0014] Another aspect of the spray coating apparatus of the present invention that solves the above problems comprises a spray nozzle having a plurality of coating liquid discharge ports arranged in the width direction, and a pair of air discharge ports arranged near the coating liquid discharge ports, opening continuously or intermittently in the width direction to sandwich the coating liquid discharge ports, a supply means for supplying coating liquid and air to the spray nozzle, and a transport means for transporting a substrate to be coated on which a coating film is formed. The above-described transport means transports the coated substrate while extending beyond both sides in the width direction of the substrate to be coated, in the area facing the tip of the spray nozzle, and supporting the surface of the coated substrate opposite to the surface on which the coating film is formed. The width of the air outlet is the length by which the projection image of the air outlet onto the conveying means extends beyond both sides in the width direction of the conveying means.

[0015] The spray coating apparatus of the present invention in this alternative embodiment preferably has the following form. (1) The width of the air discharge port is 10 mm or more wider than the width of the conveying means on one side. (2) The width of the coating liquid discharge port is smaller than the width of the substrate to be coated.

[0016] In the present application, the "width direction" means the direction in which a plurality of coating liquid discharge ports are arranged. Further, the "inner side" means the central side of the nozzle in the width direction, and the "outer side" means the position opposite to the "inner side".

Effect of the Invention

[0017] By using the method for manufacturing a substrate with a coating film of the present invention, variations near the widthwise ends of the coating film can be reduced, and a coating film can be widely and uniformly formed on the substrate.

Brief Description of the Drawings

[0018] [Figure 1] It is a perspective view showing a schematic configuration of a spray nozzle used in the method for manufacturing a substrate with a coating film of the present invention. [Figure 2] It is a bottom view seen from the coating liquid discharge port side showing the configuration of the tip of a spray nozzle used in the method for manufacturing a substrate with a coating film of the present invention. [Figure 3] It is an enlarged cross-sectional view of a spray nozzle explaining the formation of a coating film and the flow of discharge air during coating of a spray nozzle used in the method for manufacturing a substrate with a coating film of the present invention. [Figure 4] It is an enlarged cross-sectional view explaining characteristic dimensions at the tip of the spray nozzle in FIG. 1. [Figure 5] It is an enlarged front view of the widthwise end of a spray nozzle during spray nozzle coating in a method for manufacturing a substrate with a coating film different from the present invention, explaining the generation principle of vortex flow at the end of the substrate to be coated. [Figure 6] It is an enlarged front view of the widthwise end of a spray nozzle explaining the air flow at the end of the substrate to be coated during spray nozzle coating in the method for manufacturing a substrate with a coating film of the present invention. [Figure 7] Figure 6(b) is an enlarged view illustrating in more detail a configuration in which the substrate to be coated is supported by a backup roll, and an open space exists. [Figure 8] Figure 1 is an exploded perspective view illustrating the components of a spray nozzle. [Figure 9] This is a side view showing a schematic configuration of a spray coating apparatus used in the method for manufacturing a substrate with a coated film according to the present invention. [Modes for carrying out the invention]

[0019] The inventors diligently investigated the above problems and discovered that after air discharged from a spray nozzle collides with the substrate to be coated (hereinafter sometimes simply referred to as the substrate), the air discharged from around both ends of the air outlet generates vortex flow around the widthwise edges of the substrate. This vortex flow causes the discharged air and flying coating droplets to twist inward, preventing the coating droplets from adhering to the edges of the substrate, resulting in thinning of the coating film around both ends. Furthermore, they discovered that a portion of the air forming the vortex flow flows inward, causing the flying coating droplets to be carried inward, resulting in thinning or thickening of the coating film over a wide area around the coating edges. From this, they found that by making the projection image of the air outlet onto the substrate extend beyond both ends in the widthwise direction of the substrate, and by allowing a portion of the air discharged from the air outlet to blow through a virtual plane that passes outside the substrate, on the side opposite to the surface on which the coating film is formed, the vortex flow can be reduced, and variations in the coating film edges can be reduced.

[0020] Furthermore, there are no particular restrictions on the gaseous components of the air or ambient air used in this invention, as long as it is a gas suitable for coating, such as air or nitrogen gas can be used. Also, there are no particular restrictions on the ambient pressure of the ambient air, and it can be an atmospheric pressure environment or a reduced pressure environment, etc.

[0021] Furthermore, there are no particular restrictions on the coating liquid used for spray coating, and examples include solutions of inorganic or organic substances, or slurries in which inorganic or organic substances are dispersed in a binder and a solvent. The viscosity of the coating liquid needs to be low enough that the coating liquid can be atomized by the force of the discharged air, and is generally preferably 500 mPas or less.

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings. The following description is provided to facilitate understanding of the present invention and does not limit it in any way. The scope of the present invention is not limited to the following embodiments and includes all modifications within the scope equivalent to the configurations described in the claims.

[0023] Figure 1 is a perspective view showing the schematic configuration of a spray nozzle used in the method for manufacturing a coated substrate according to the present invention. The spray nozzle 10 has a longitudinal direction perpendicular to the transport direction D of the long substrate 40, i.e., in the width direction of the substrate 40, and is positioned at a certain distance from the substrate 40 so as to face the coated surface of the substrate 40. The coating liquid is supplied from a coating liquid supply port 16 located in the center of the width direction of the spray nozzle 10, widened in the width direction by a coating liquid manifold 18, and discharged from a coating liquid discharge port 31 located at the tip of the spray nozzle 10. The discharged air is supplied from air supply ports 15a and 15b located in the center of the width direction of the front and back of the spray nozzle 10, respectively, widened in the width direction by air manifolds 17a and 17b, and discharged from air discharge ports 33a and 33b, and the coating liquid discharged from the coating liquid discharge port 31 is dropletized by the force of the air. The dropletized coating liquid adheres to the substrate 40, which is transported by the flow of discharged air, thereby forming a coating film 41. In this case, if the width of the substrate is W4 and the width of the coating film is W6, then W6 ≤ W4 can be set. Although not shown in this figure, a backup roll may be provided as a substrate support means, which contacts the opposite side of the coated surface of the substrate at the coating film formation position.

[0024] Next, Figure 2 is a bottom view taken from the coating liquid discharge port side, showing the configuration of the tip of a spray nozzle used in the method for manufacturing a coated substrate of the present invention. In the bottom view of the spray nozzle 10 shown in Figure 2, the coating liquid discharge port 31 has a rectangular opening, and multiple coating liquid discharge ports 31 are arranged at equal intervals in the width direction, forming an overall coating liquid discharge width W1. The coating liquid discharge width W1 is approximately the same width as the coating film width W6 shown in Figure 1. The optimal width W2 of each coating liquid discharge port 31 varies depending on the viscosity of the coating liquid used and the flow rate of the coating liquid to be discharged, but it is preferably 100 μm or more from the viewpoint of reducing shape variations between discharge ports, and preferably 400 μm or less in order to distribute a uniform amount of coating liquid from the coating liquid manifold to each coating liquid discharge port. Furthermore, the arrangement pitch W7 of the coating liquid discharge ports 31 is preferably 10 mm or less from the viewpoint of coating film uniformity.

[0025] Next, near the coating liquid discharge port 31, a pair of slit-shaped air discharge ports 33a and 33b with an air discharge width W3 are arranged so as to sandwich the coating liquid discharge port 31. The air discharge width W3 is longer than the coating liquid discharge width W1 in order to uniformly atomize all the coating liquid discharged from each coating liquid discharge port 31 with the force of the air. The dashed lines indicated by reference numerals 44L and 44R indicate the positions of both ends in the width direction of the substrate, and the air discharge width W3 is wider than the width W4 of the substrate and extends outward from both ends in the width direction of the substrate. Note that the air discharge ports 33a and 33b may open as a single continuous slit across the width direction as shown in Figure 2, or they may open intermittently in a one-to-one correspondence with the coating liquid discharge port 31. If they open intermittently, they may be circular, elliptical, etc. When they open intermittently, it is preferable to make the opening length in the width direction greater than W2. Furthermore, while the coating liquid discharge width W1 can be set to the desired discharge width, it is preferable to set W1 ≤ W4 in order to minimize the scattering of coating liquid droplets.

[0026] Next, Figure 3 is an enlarged cross-sectional view of a spray nozzle used in the method for manufacturing a coated substrate of the present invention, illustrating the formation of the coating film and the flow of discharged air during coating. In the spray nozzle 10 shown in Figure 3, the coating liquid F is discharged from the coating liquid discharge port 31, and air G is discharged from a pair of air discharge ports 33a and 33b. The discharged coating liquid F forms a coating liquid reservoir 37, and the impact force of the discharged air causes the coating liquid reservoir 37 to become fine coating liquid droplets 42, which then fly while diffusing in the forward and backward directions of the transport direction D, adhering to the substrate 40 and forming a coating film 41. In addition, most of the discharged air G, after colliding with the substrate 40, branches out in the forward and backward directions of the transport direction D and flows away from the spray nozzle 10. The supply conditions for the air G discharged from the air outlets 33a and 33b cannot be defined in general terms, as they depend on the desired type of coating liquid, coating film thickness, etc. However, from the viewpoint of minimizing the air flow rate used while maintaining the impact force for atomizing droplets, it is preferable that the air flow rate is 500 NL / min or more and 1200 NL / min or less per 1 m of air discharge width.

[0027] Next, Figure 4 is an enlarged cross-sectional view illustrating the characteristic dimensions at the tip of the spray nozzle in Figure 1. In Figure 4, the angle θ between the coating liquid discharge port 31 and the air discharge ports 33a and 33b is preferably 15 degrees or more and 45 degrees or less. When θ is 15 degrees or more, the air discharged from the air discharge ports 33a and 33b can impart sufficient force to the coating liquid to form droplets. When θ is 45 degrees or less, fewer coating liquid droplets fly in the direction of substrate travel, so fewer coating liquid droplets scatter without adhering to the substrate, and the efficiency of using the coating liquid does not decrease.

[0028] The optimal gap L1 between the coating liquid outlets 31 varies depending on the viscosity of the coating liquid used and the flow rate of the coating liquid being discharged. However, from the viewpoint of reducing variations in the shape of each outlet, a gap of 50 μm or more is preferred, and a gap of 300 μm or less is preferred in order to ensure a uniform amount of coating liquid is distributed from the coating liquid manifold to each coating liquid outlet 31.

[0029] The distance L2 between the coating liquid discharge port 31 and the air discharge ports 33a and 33b is preferably 100 μm or less. When L2 is 100 μm or less, the distance from the air discharge port tips 33a and 33b to the impact point is short, so the impact force of the air applied to the coating liquid can be sufficiently large.

[0030] The gap L3 between the air outlets 33a and 33b is preferably 100 μm or less. When L3 is 100 μm or less, the average flow velocity of the discharged air is sufficiently large, and it is easy to atomize the coating droplets even when the discharged air flow rate is reduced.

[0031] Next, Figure 5 is an enlarged front view of the widthwise end of a spray nozzle during spray nozzle application in a method for manufacturing a coated substrate different from the present invention, illustrating the principle of vortex flow generation at the edge of the substrate to be coated. Figure (a) shows a configuration in which the width of the air outlet does not extend beyond both sides in the width direction of the substrate to be coated. Figure (b) shows a configuration in which the width of the air outlet extends beyond both sides in the width direction of the substrate to be coated, and furthermore, a backup roll supporting the substrate to be coated exists in the area where the air outlet extends beyond.

[0032] Figure 5(a) schematically shows how a vortex flow V is generated near the widthwise end of the substrate 40 by air G discharged from a spray nozzle 10, with the tip portion of one end in the widthwise direction extracted. The dashed line indicated by reference numeral 38L indicates the position of the air discharge port end. This vortex flow V is generated by the following principle. First, most of the air G discharged from the spray nozzle 10 branches in the direction of substrate transport (perpendicular to the plane of the paper in Figure 5), as shown in Figure 3. However, the air G1 discharged near the air discharge port end 38L, after colliding with the substrate 40, changes direction and flows outward (air G2) because the pressure on the outside where no air flow is generated is lower than the pressure on the inside of that position. A portion of this air G2 (air G3) separates on or at the end of the substrate 40 (G3) and is attracted to the faster flow of discharged air G1 by the Coanda effect, circulating and forming a vortex flow V. The air G3 trapped in the vortex flow V formed in this way flows in a spiral in the vortex axis direction (perpendicular to the plane of the paper), and some of the air G4 separates from the vortex and flows towards the inside of the substrate. This vortex flow V changes the flow of air G1 discharged at the end of the air outlet inward, causing the coating droplets to flow inward and resulting in thinning at the edges of the coating film. In addition, the inward-flowing air G4 carries the coating droplets that have diffused in the forward and backward directions of the substrate transport direction shown in Figure 3 towards the center, causing thinning or thickening over a wide area around the edges of the coating film.

[0033] Next, in the configuration shown in Figure 5(b), the width of the air outlet extends beyond both sides of the width direction of the substrate 40, but the backup roll 90 is wider than the substrate 40, and in this area the air G collides with the surface 92 of the backup roll 90. Generally, the substrate 40 is a thin film with a thickness of several hundred μm, and its size is negligible compared to the spray distance of the spray nozzle (distance from the tip of the spray nozzle to the substrate). Therefore, the substrate 40 and the backup roll surface 92 are substantially the same plane, and in this configuration as well, a swirling flow can be generated by the same principle as in Figure 5(a).

[0034] Next, Figure 6 is an enlarged front view of the widthwise end of the spray nozzle, illustrating the airflow at the edge of the substrate to be coated during spray nozzle application in the manufacturing method of the coated substrate of the present invention. Figure (a) shows a configuration in which the width of the air outlet extends beyond both sides in the width direction of the substrate to be coated. Figure (b) shows a configuration in which the substrate to be coated is supported by a backup roll, and there is also a blow-through space.

[0035] In the configuration shown in Figure 6(a), there is nothing supporting the substrate 40 in the area opposite the tip of the spray nozzle 10. Therefore, a portion of the air G discharged from the spray nozzle 10 blows through a virtual surface P (air G5) that passes on the outer side of the substrate 40 in the width direction, on the side opposite to the surface on which the coating film is formed. This blowing air G5 suppresses the outward flow change of the air G that collides with the edge of the substrate 40, thereby reducing the generation of swirling flow and reducing variations in the coating film edge. The blowing width W5 of the discharged air is defined as the distance from the position where the discharged air G passes through the virtual surface P at the innermost point in the width direction to the end of the air outlet 38L. In this figure, W5 is the distance from the end of the substrate 40 on one side in the width direction to the air outlet 38L. It is desirable that this blowing width W5 be 10 mm or more in order to sufficiently suppress the outward flow change in the width direction of the discharged air G that does not pass through the virtual surface P. Furthermore, the faster the airflow velocity from the spray nozzle, the larger the vortex flow generated. However, the faster the airflow velocity as it passes through, the greater the effect of suppressing vortex generation. Therefore, regardless of the air discharge conditions, the desirable blow-through width W5 is 10 mm or more.

[0036] In the configuration shown in Figure 6(b), the backup roll 90 supports the substrate 40 in the area opposite to the tip of the spray nozzle 10, and there is also a blow-through space S (a grid-like shaded area). The "blowing-through space" is a space where no objects exist, through which the discharged air G flows as it passes through a virtual surface P. In the blow-through space S, a portion of the discharged air G passes through a virtual surface P that is on the outside in the width direction of the substrate 40 and on the opposite side of the surface on which the coating film is formed on the substrate 40. Therefore, similar to the configuration in Figure 6(a), the generation of swirling flow is reduced, and variations at the edges of the coating film can be reduced.

[0037] Next, Figure 7 is an enlarged view that further explains in detail the configuration in which the substrate to be coated is supported by the backup roll in Figure 6(b), and an open space exists. Figures (a) and (b) show different configurations of the shape of the backup roll, respectively.

[0038] As shown in Figure 7(a), when the width of the backup roll 90 is wider than that of the substrate 40 on one side, the blow-through width W5 of the air G is the distance from the end 94 of the backup roll 90 to the end 38L of the air outlet. Also, since the air G that has blown through the virtual surface P may collide with the axial surface 93 of the backup roll and generate a vortex flow V, it is preferable that the height H1 of the blow-through space S from the virtual surface P to the point where the blown-through air collides with some structure be as high as possible. In other words, if the distance from the virtual surface P (backup roll surface) to the axial surface 93 is made sufficiently long, even if a vortex flow V is generated, the location where the vortex flow is generated is farther away from the substrate position as seen from the spray nozzle 10, and the discharged air velocity is low, so the vortex flow V also becomes weaker. In addition, since the vortex flow is generated at a location farther away from the substrate, the impact on coating can be reduced. Specifically, it is preferable to set the height H1 of the blow-through space S to 10 mm or more, as this can further reduce the impact on coating. Furthermore, since the generation of vortex flow V is caused by a change in the outward flow of air G discharged from near the air outlet end 38L, the height H1 of the blow-through space S is defined as the blow-through distance at the position of the air outlet end 38L1 within the width direction of the blow-through space S. That is, as shown in Figure 7(b), a tapered portion 96 is provided at the end 94 of the backup roll 90, and when the backup roll end 94 is located outside the air outlet end 38L, the height H1 of the blow-through space S is the distance from the virtual plane P to the projection position of the tapered portion 96 surface of the air outlet end 38L. Also, the blow-through width W5 is the distance in the width direction from the edge 96 of the tapered portion to the air outlet end 38L.

[0039] The form of the open space S was explained using the shape of a backup roll as an example with Figures 6 and 7, but the same applies even if other structures other than the backup roll are present.

[0040] Next, Figure 8 is an exploded perspective view illustrating the configuration of the spray nozzle in Figure 1. In Figure 8, the spray nozzle 10 is composed of parts labeled 12, 13a, 13b, 14a, and 14b. Reference numerals 13a and 13b are inner blocks for forming the coating liquid manifold and coating liquid outlet. One of the inner blocks 13a has a coating liquid supply port 16 for receiving the coating liquid and a coating liquid manifold 18 for widening the coating liquid in the width direction, with the coating liquid supply port 16 communicating with the coating liquid manifold 18. Next, reference numeral 12 is a comb-shaped shim sandwiched between the inner blocks 13a and 13b, and when the inner blocks 13a and 13b and the shim 12 are joined together, the gaps between the comb teeth of the shim 12 form multiple coating liquid outlets in the width direction. Reference numerals 14a and 14b are outer blocks, and when joined with the inner blocks 13a and 13b, respectively, they form air outlets for discharging air. In this case, the shape of the air outlet is a single continuous slit in the width direction. Each outer block 14a, 14b has an air supply port 15a, 15b that receives air, and an air manifold 17a, 17b on the mating surface side with the outer blocks 14a, 14b that expands the air in the width direction, with the air supply ports 15a, 15b communicating with the air manifolds 17a, 17b.

[0041] Next, Figure 9 is a side view showing a schematic configuration of a spray coating apparatus using the method for manufacturing a coated substrate according to the present invention. In this figure, the width direction is perpendicular to the plane of the paper.

[0042] The spray coating apparatus 60 in Figure 9 consists of a coating means 80 having a spray nozzle 10 as described in Figures 1, 2, and 8, a supply means 70 for supplying coating liquid and air to the spray nozzle 10, and a transport means 61 for transporting the substrate 40 on which the coating film 41 will be formed. The coating means 80 consists of the spray nozzle 10, a booth 82 covering them, a waste liquid recovery tank 83, and a depressurization means 84. The booth 82 is a substantially sealed system except for the inlet opening 85 and outlet opening 86 through which the substrate 40 passes, preventing coating droplets discharged from the spray nozzle 10 from scattering outside the coating means 80. The lower opening 87 of the booth is in communication with the waste liquid recovery tank 83, and any excess coating liquid generated inside the booth falls along the slope 88 inside the booth and is collected in the waste liquid recovery tank 83 via the lower opening 87. The rear opening 89 of the booth is connected to the depressurization means 84 via an intake pipe 90. When the depressurization means 84 is driven to create a depressurized environment inside the booth, outside air flows into the booth through the inlet opening 85 and the outlet opening 86, thus preventing the coating liquid discharged from the spray nozzle 10 from scattering outside the booth.

[0043] The supply means 70 supplies the coating liquid to the spray nozzle 10 via the coating liquid piping 73 using the coating liquid tank 71 and the metering pump 72. It also supplies air, whose pressure has been regulated by the pressurized air source 74 and the pressure regulating valve 75, to the spray nozzle 10 via the air piping 76 and the branch pipe 77.

[0044] The conveying means 61 includes a feed roll 62, which is connected to a drive means (not shown). By rotating the feed roll 62 with the drive means, the substrate 40 is conveyed in the conveying direction D at an arbitrary conveying speed.

[0045] When the conveying means 61 conveys the substrate 40 without supporting the surface of the substrate 40 opposite to the surface on which the coating film 41 is formed, or while supporting the surface of the substrate 40 opposite to the surface on which the coating film 41 is formed with the backup roll 90 to a width that fits within the width of the substrate 40, the width of the air outlet of the spray nozzle 10 is such that the projected image of the air outlet onto the substrate 40 extends beyond both sides in the width direction of the substrate 40. For the same reasons as explained in Figure 6(a), it is preferable to make the width of the air outlet 10 wider on one side than the width of the substrate 40 by 10 mm or more. Also, when the backup roll 90 extends beyond both sides in the width direction of the substrate 40 and supports the surface of the substrate 40 opposite to the surface on which the coating film 41 is formed with the backup roll 90 while conveying the substrate 40, the width of the air outlet of the spray nozzle 10 is such that the projected image of the air outlet onto the backup roll 90 extends beyond both sides in the width direction of the backup roll 90. Furthermore, for the same reasons as explained in Figure 6(a), it is preferable to make the width of the air outlet at least 10 mm wider on one side than the width of the backup roll 90.

[0046] With this spray coating apparatus 60, a portion of the air discharged from the spray nozzle 10 is blown outwards on both sides in the width direction of the substrate, away from the surface of the substrate to be coated on which the coating film is formed. This allows for the formation of a uniform coating film 41 on the conveyed substrate 40, thereby manufacturing a coated member 43. Furthermore, the apparatus may also be equipped with a drying means to dry the coating film 41 on the coated member 43 conveyed from the coating apparatus 60. The drying method for the coating film is not particularly limited, and methods such as blowing hot air or using a heat oven with a heater can be used. [Examples]

[0047] Examples are described below, but the embodiments of the present invention are not limited to these examples. Example 5 is for reference only.

[0048] Using the spray coating apparatus shown in Figure 9, conditions were prepared by varying the backup roll overhang, air outlet overhang, and blow-through distance as shown in Table 1, and these were designated as Comparative Examples 1-4 and Examples 1-5. "Backup roll overhang" refers to the length of one side of the backup roll that extends beyond the width of the substrate to be coated. "Air outlet overhang" refers to the length of one side of the air outlet that extends beyond the width of the substrate to be coated. If the air outlet overhang is negative, it means that the end of the air outlet is located inward from the edge of the substrate to be coated by that value. Furthermore, it was determined that making the air outlet overhang greater than 100 mm on one side relative to the substrate to be coated is not practically desirable because the spray nozzle and coating apparatus become too large relative to the substrate width.

[0049] In Table 1, "blowing width" refers to the value obtained by subtracting the backup roll overflow amount from the air discharge overflow amount, and represents the length of the area over which the air discharged from the air outlet blows through the virtual surface.

[0050] "Blowthrough distance" refers to the distance from a virtual surface to a structure, such as the support shaft of a backup roll, before the air that has blown through the virtual surface collides with it.

[0051] The spray nozzle had a coating liquid outlet spacing of 2 mm, a coating liquid outlet spacing of 200 μm, a spacing of 200 μm between the coating liquid outlet and the air outlet, an air discharge angle of 25 degrees, a single slit shape with an air outlet spacing of 50 μm, and an air outlet length of 1 mm (length from the air manifold to the nozzle tip). The width of the coating liquid outlet was 5 mm shorter on each side than the width of the air outlet. The distance from the spray nozzle tip to the substrate was 120 mm, and the air discharge pressure was adjusted to 15 kPa with a pressure regulating valve. The substrate was a PET film with a substrate width of 600 mm and a thickness of 100 μm, and was transported at a speed of 1 m / min. The configuration of the backup roll was the same as that shown in Figure 7(a).

[0052] Furthermore, since the width of the coating liquid discharge port is fixed to be 5 mm shorter on one side than the width of the air discharge port, there are examples and comparative examples in which the coating liquid discharge port extends beyond the width of the substrate. However, in these examples and comparative examples, it is necessary to spray the water droplets beyond the width of the substrate in order to observe the flying water droplets and confirm whether or not vortices are generated.

[0053] [Evaluation of the presence or absence of vortices] First, to evaluate the presence or absence of vortex flow, air was discharged from the air outlet and pure water from the coating liquid outlet, and the flow of the resulting fine water droplets was visualized using an LED light source to determine the state of vortex flow. The state of vortex flow was evaluated according to the following evaluation rank. The evaluation results are shown in the "Vortex Flow" column of Table 1.

[0054] [Vortex flow evaluation rank] ○: No vortex flow occurred. △: A vortex flow occurs that crosses the virtual surface. ×: Vortex flow occurs on the coated surface side of the substrate.

[0055] In Comparative Examples 1 and 2, vortex flow was generated on the substrate.

[0056] In Example 1, a vortex flow was generated at the edge of the substrate, but the force of the vortex flow was weaker than in Comparative Examples 1 and 2 due to the discharged air trying to blow through.

[0057] In Example 2, no vortex flow was generated due to the effect of the discharged air blowing through the outside of the substrate.

[0058] In Examples 3 and 4, vortex flows crossing a virtual plane were generated by air impacting the axial surface of the backup roll, but their intensity was weaker than that of Comparative Examples 1 and 2.

[0059] In Example 5, the backup roll extended beyond the substrate, but the discharge air blowing through the outside of it prevented the generation of vortex flow.

[0060] In Comparative Examples 3 and 4, the air outlets protruded outward from the substrate, but vortex flow was generated at these points due to the air colliding with the backup roll.

[0061] Based on the above, it was confirmed that vortex flow is reduced when a portion of the air discharged from the air outlet blows through a virtual surface that passes on both outer sides in the width direction of the substrate, on the side opposite to the surface on which the coating film of the substrate is formed.

[0062] [Evaluation of coating film uniformity] Next, to evaluate the uniformity of the coated film, the coating solution and the width of the coating solution nozzle were changed. The coating solution used was a dispersion of a resist pigment with a solid content concentration of 14% and a viscosity of 4.0 cp dispersed in propylene glycol monomethyl ether acetate (PMA). The width of the coating solution nozzle was set to be 5 mm shorter on one side than the width of the substrate. The coating solution was sprayed from the nozzle so that the coated film thickness after drying would be 20 μm, and the coated film was formed on the PET film by hot air drying. The coated film thickness of the prepared coated film was measured at 10 mm intervals in the width direction, and the uniformity of the coated film was evaluated according to the evaluation rank shown below. The evaluation results are shown in the "Coated Film Uniformity" column of Table 1. The film thickness variation (%) was calculated using the following formula 1. Equation 1) Film thickness variation (%) = {Film thickness at measurement point - Average film thickness at the center) / Average film thickness at the center} × 100.

[0063] [Evaluation rank for uniformity of coating film] ◎: No film thickness variations exceeding 10% occurred. ○: Film thickness variation exceeding 10% occurs within a range of less than 30 mm. △: Film thickness variation exceeding 10% occurs in the range of 30 mm to less than 50 mm. ×: Film thickness variation exceeding 10% occurs in a range of 50 mm or more.

[0064] In Comparative Examples 1 and 2, widespread variations in film thickness occurred at the edges of the coated film.

[0065] In Example 1, a reduction in film thickness variation was observed compared to Comparative Examples 1 and 2, which also exhibited film thickness variation.

[0066] No film thickness variations occurred in Examples 2, 4, and 5. In Example 3, although film thickness variations occurred due to the influence of vortex flow across the virtual plane, a reduction in film thickness variations was confirmed compared to Comparative Examples 1 and 2.

[0067] In Comparative Example 3, widespread variations in film thickness occurred at the edges of the coated film. This is thought to be due to the influence of vortex flow generated on the backup roll.

[0068] In Comparative Example 4, compared to Comparative Example 3, the air outlet end was further away from the edge of the substrate, which reduced the effect of vortex flow and thus reduced film thickness variation. However, despite the large amount of air outlet overhang, the effect of reducing film thickness variation was small.

[0069] The above examples confirmed that reducing vortex flow reduces variations in film thickness at the edges, thus confirming the effectiveness of the present invention.

[0070] [Table 1] [Explanation of Symbols]

[0071] 10 spray nozzles 12. Comb-shaped shims 13a, 13b Inner nozzle block 14a, 14b Outer nozzle block 15a, 15b Air supply ports 16 Coating liquid supply port 17a, 17b Air Manifold 18. Coating liquid manifold 31 Application liquid discharge port 33a, 33b Air discharge port 34 Liquid-holding surface forming member 35L, 35R liquid holding surface 36L, 36R Nozzle tip 37. Liquid reservoir 38L, 38R Air outlet end 40 Substrate to be coated 41 Coating film 42 Application droplet 43 Substrate with coated film 44L, 44R Edge of substrate to be coated 60 Spray coating device 61 Conveying means 62 Feed Roll 70 Means of supply 71 Coating liquid tank 72 Metering pump 73. Coating liquid piping 74 Pressurized air source 75 Pressure regulating valve 76 Air Piping 77 Branch pipe 80 Coating means 81 Intake pipe 82 booths 83. Drainage recovery tank 84 Depressurization means 85 Inlet opening 86 Exit opening 87 Lower opening 88 Booth Slope 89 Back opening 90 Backup Roles 92 Backup roll surface 93 Shaft surface 94 Backup roll end 95 Tapered section 96 Ridge D Conveying direction F Coating solution G, G1, G2, G3, G4, G5, G6 Discharge Air H1 Open space distance L1 Gap between coating liquid discharge port L2 Distance between the coating liquid outlet and the air outlet L3 Air outlet spacing P Virtual Surface S Open space V-shaped vortex flow W1 Coating liquid discharge width W2 Coating liquid discharge port width W3 Air discharge width W4 Width of substrate to be coated W5 Open space width W6 Coating film width W7 Arrangement pitch of coating liquid discharge ports θ Air discharge angle

Claims

1. A method for manufacturing a coated substrate by spraying coating droplets from a nozzle onto a transported substrate to be coated, wherein a coated film is formed on the substrate, As the nozzle, The system includes a coating liquid discharge port that discharges the coating liquid over a width direction intersecting the transport direction of the substrate to be coated, and a pair of air discharge ports that are arranged near the coating liquid discharge port, opening continuously or intermittently over the width direction, and flanking the coating liquid discharge port, to discharge air. The width of the coating liquid discharge port is smaller than the width of the substrate to be coated, A spray nozzle is used, which discharges the coating liquid from the coating liquid outlet while simultaneously causing air discharged from the air outlet to collide with the coating liquid to form coating droplets. Within the range facing the tip of the spray nozzle, the substrate to be coated is transported while supporting the surface of the substrate to be coated that is opposite to the surface on which the coating film is formed, with a width that fits within the width of the substrate to be coated. A portion of the air discharged from the air outlet blows through a virtual surface that passes on both sides of the width direction of the substrate to be coated, on the surface of the substrate to be coated that is opposite to the surface on which the coating film is formed. A method for manufacturing a substrate with a coated film.

2. A method for manufacturing a substrate with a coating film according to claim 1, wherein the width of the air blowing through the virtual surface is 10 mm or more on one side.

3. A spray coating apparatus comprising: a spray nozzle having a plurality of coating liquid discharge ports arranged in the width direction, and a pair of air discharge ports arranged near the coating liquid discharge ports, opening continuously or intermittently across the width direction to sandwich the coating liquid discharge ports; a supply means for supplying coating liquid and air to the spray nozzle; and a transport means for transporting a substrate to be coated on which a coating film is formed, The conveying means conveys the substrate to be coated while supporting the surface of the substrate to be coated that is opposite to the surface on which the coating film is formed, within a range facing the tip of the spray nozzle, with a width that fits within the width of the substrate to be coated. The width of the air outlet is such that the projection image of the air outlet onto the substrate to be coated extends beyond both sides in the width direction of the substrate to be coated. The width of the coating liquid discharge port is smaller than the width of the substrate to be coated. Spray coating device.

4. The spray coating apparatus according to claim 3, wherein the width of the air outlet is 10 mm or more wider on one side than the width of the substrate to be coated.

Images