Horizontal coating device and coating method using same

Abstract

Conventional examples of liquid coating devices have had the problem of being unable to coat a large area with a uniform liquid coating. In order to solve this problem, the present invention provides: a horizontal coating device comprising a substrate placement table, an electric actuator, a plate, a coating part, and a conveyance part; and a coating method using the horizontal coating device. A coating unit of the coating part includes a coating bar, a spring, a coating holder, and a melamine sponge. The inside of the coating holder is filled with a coating liquid having an adjusted viscosity, and the melamine sponge is impregnated with the coating liquid. The conveyance part can cause the coating part to move forward or move backward by sliding a linear block to which the plate on a linear guide rail is fixed by a motion of a ball screw so as to move the linear block forward or backward.

Description

Horizontal Coating Device and Coating Method Using the Same

[0007] ,

[0001] The present invention relates to a horizontal coating device for uniformly coating a coating liquid on a large-sized substrate such as glass or resin, and a coating method using the same.

[0002] There is a need to uniformly coat a thin film for a solar cell, a transparent conductive film, or a heat insulating thin film on a large-sized glass substrate or resin substrate. In order to form such a coating film, a slit coater having a discharge port formed of a slit that is long in the width direction has been conventionally used. The coating liquid is discharged from the discharge port onto the substrate to form a coating film of the coating liquid on the substrate.

[0003] In particular, regarding the heat insulating thin film, among those that have been put into practical use so far, there is one that forms a low emissivity thin film (so-called LowE film) on a large-sized substrate using a physical vapor deposition method called sputtering, but a method of coating and forming a coating liquid on a large-sized substrate has not been put into practical use.

[0004] Japanese Patent Application Laid-Open No. 2012-183469, Japanese Patent Application Laid-Open No. 2017-148769, Japanese Patent Application Laid-Open No. 2015-192984

[0005] The problem to be solved is that in the conventional coating liquid coating device, a uniform coating film of the coating liquid cannot be easily coated over a large area.

[0006] Patent Document 1 aims to suppress fluctuations in the width direction dimension of the coating film formed by the applied coating liquid while making it easy to change the discharge width. A slit nozzle is formed with a discharge port consisting of a slit that is long in the width direction, and the coating liquid is discharged from the discharge port onto the substrate for coating. A drive unit moves the substrate in the front-rear direction with respect to this slit nozzle, and a discharge width changing member changes the width direction dimension of the discharge port by moving in the width direction within the slit. It is a coating device provided with an air supply unit that has an air nozzle for blowing air onto regions on both outer sides in the width direction of the coating liquid discharged from the discharge port, and can adjust the blowing position of the air by the air nozzle according to the change in the width direction dimension of the discharge port. However, in this method, the film thickness on both outer sides in the width direction of the substrate becomes thick, so air must be blown by the air nozzle to adjust it.

[0007] Patent Document 2 aims to achieve a desired thickness for the coating film applied to the substrate. The coating apparatus has a reservoir for storing the coating liquid, a discharge port for discharging the coating liquid, and a slit-shaped channel connecting the reservoir and the discharge port, discharging the coating liquid from the discharge port onto the substrate. The coating apparatus includes a moving means for moving the coating apparatus in a direction parallel to the surface to be coated relative to the substrate, a pump for supplying the coating liquid to the coating apparatus, and a control device. The control device controls the supply of coating liquid from the pump to the coating apparatus while creating a negative pressure in the coating liquid inside the coating apparatus during the coating operation, which involves discharging the coating liquid from the discharge port onto the substrate while moving the coating apparatus. However, in this method, in order to achieve a desired thickness for the coating film, it is necessary to control the supply of coating liquid from the pump to the coating apparatus while creating a negative pressure in the coating liquid inside the coating apparatus.

[0008] Patent Document 3 aims to provide a coating apparatus and coating method that enables the formation of a thin coating film of uniform thickness by ensuring that a constant pressure acts on the bead during coating film formation in a capillary coating with the nozzle discharge port facing downward, and that maximizes the area of ​​uniform thickness of the product by appropriately controlling the amount of coating liquid supplied to the bead at the start and end of the coating process. The apparatus comprises a coating device having a coating liquid storage section, a supply channel, a discharge port, a slit-shaped channel connecting the coating liquid storage section and the discharge port, a moving means for moving the coating device, a lifting device, and a pressure applying device for applying pressure to the coating liquid in the coating device, and is equipped with a pressure gauge for measuring the pressure in the coating liquid storage section. The pressure applying device comprises a tank, an on / off valve, a pressure actuator, and a pressure control device that controls the operating pressure of the pressure actuator based on the pressure in the coating liquid storage section. However, this apparatus requires a complex pressure control device and pressure actuator.

[0009] To solve the above-mentioned conventional problems, the present invention comprises a substrate mounting table on which a substrate is placed, an electric actuator, a plate, a coating unit, and a transport unit, wherein the coating unit comprises a cylinder for raising and lowering the coating unit and a linear shaft provided at the tip of the electric actuator, and a coating unit attached to the electric actuator via the cylinder for raising and lowering the coating unit, the coating unit is a unit comprising a coating bar, a coating holder, and a melamine sponge, the electric actuator is fixed to the plate, and two linear shafts provided spaced apart on both sides of the electric actuator pass through holes provided in the plate and are fixed to the coating unit to support the coating unit, and the coating The coating bar and coating holder of the unit are connected via a mounting bracket and a spring, the coating holder is filled with a coating liquid adjusted to a viscosity of 2 to 10 cP (centipoise), the coating liquid impregnates the melamine sponge, the transport unit comprises a servo motor, a ball screw, a timing belt, a linear guide rail, and a linear block, the transport unit moves forward or backward the coating unit, which is attached to the plate and the plate via an electric actuator fixed to the plate and an electric actuator via a cylinder for moving the coating unit up and down, so that the melamine sponge impregnated with the coating liquid moves forward or backward on the surface of the substrate.

[0010] Furthermore, the second invention of this application is a coating method using the horizontal coating apparatus, characterized in that a substrate is placed on the substrate placement table, the coating unit is moved downward by lowering the cylinder for vertical movement of the coating unit in response to a command from the electric actuator, the melamine sponge impregnated with a coating liquid adjusted to a viscosity of 2 to 10 cP (centipoise) at the tip of the coating unit is brought into contact with the substrate surface, the servo motor is rotated in response to a command from the electric actuator, the rotational force is transmitted to the ball screw via the timing belt, the rotational movement of the ball screw causes the linear block, to which the ends of the plate on the linear guide rails on both sides of the coating unit are fixed, to slide forward or backward, so that the plate, the electric actuator fixed to the plate, and the coating unit attached from the electric actuator via the cylinder for vertical movement of the coating unit move forward or backward on the substrate surface, thereby coating the substrate surface with the coating liquid impregnated in the melamine sponge.

[0011] Figure 1 (perspective view) shows the external appearance of the horizontal coating apparatus of the present invention. It shows the state before the lower half of the linear shaft on the coating unit side is inserted into the upper half of the linear shaft on the plate side, and before the electric actuator and the cylinder for moving the coating unit up and down are coupled. At the bottom is the substrate mounting table on which the substrate is placed, and the coating unit that applies the coating liquid to the substrate set on the substrate mounting table is visible on the right. The front and back are the transport section, which contains a ball screw that converts the rotational motion of the servo motor into forward and backward motion, and the linear block that moves in conjunction with the ball screw on a linear guide rail. What is visible at the top back is a cable carrier (registered trademark) for moving the control system cables in accordance with the movement of the coating section.

[0012] Figure 2 shows a front view of the horizontal coating apparatus of the present invention. On the left side of the front view are the linear guide rail and linear block of the transport unit, and above them is a cable carrier (registered trademark) bundling the cables of the control system. On the right side of the front view is the transport unit, which includes the servo motor, the ball screw, the linear guide rail and the linear block. The plate is fixed to the linear block at its end. The central coating unit is driven up and down by the transport unit in a direction perpendicular to the paper plane, and coats the coating liquid onto the substrate on the substrate mounting table. Below the substrate mounting table, there are glass transport rollers and suction cups for fixing the substrate so that the substrate can be moved manually. This arrangement is a so-called gantry type, in which the transport unit is formed to straddle the coating unit.

[0013] Figure 3 shows a side view of the horizontal coating apparatus of the present invention. The substrate placement table moves the substrate using substrate transport rollers and secures the substrate with suction cups. The substrate can be manually moved back and forth and left and right on the transport rollers. The coating unit is located directly below the electric actuator, but moves from left to right in this figure together with the electric actuator by the transport unit. The cable carrier (registered trademark) moves similarly to the movement of the coating unit.

[0014] Figure 4 is a schematic diagram illustrating the details of the coating section. The coating liquid is automatically supplied from a coating liquid tank (not shown) to the coating holder 6 via a coating liquid transport pipe (not shown) by a dispenser (not shown), and impregnated into the melamine sponge 8. The melamine sponge 8, impregnated with the coating liquid, then moves along the substrate surface of the float glass 10, in a direction perpendicular to the plane of the paper in this figure, thereby applying the coating liquid to the substrate surface of the float glass 10. The thickness of the coating film is determined by the self-leveling effect of the coating liquid, whose viscosity is adjusted to 2 to 10 cP (centipoise), and is approximately 2 μm to 5 μm. However, the amount of coating liquid discharged can also be adjusted by changing the pressing force on the melamine sponge 8 by moving the coating unit's vertical cylinder 7 up and down with the electric actuator 1. The coating unit's vertical cylinder 7 is operated so that it is pressed firmly when the thickness of the coating film is to be increased, and weakly when the thickness of the coating film is to be decreased. The coating bar 5 and coating holder 6 of the coating unit are connected by a mounting bracket 20 and a spring 9. The coating unit is supported by linear shafts 21 located on both outer sides, spaced apart from the electric actuator 1, and can slide smoothly up and down due to the action of linear bushings provided at the position where the linear shafts 21 pass through the plate 4. In Figure 4, the linear bushing is the thickened portion at the position where the linear shaft 21 passes through the plate 4 in the center. The coating unit moves up and down by a coating unit vertical cylinder 7 while being supported by the linear shafts 21, and is also able to move like a pendulum, so that the coating unit (and therefore the melamine sponge) is pressed correctly perpendicularly against the substrate.The coating unit moves in the longitudinal direction of the substrate (perpendicular to the plane of the paper). This movement is caused by a signal from the electric actuator 1, which rotates the servo motor 16. The rotational force is transmitted to the ball screw 15 by a timing belt, and the ball screw 15 converts the rotational force into forward and backward motion. The linear block 2, to which the end of the plate 4 is fixed, moves along the linear guide rail 3, causing the coating unit to move in the forward and backward direction (perpendicular to the plane of the paper). The melamine sponge 8 moves in the forward and backward direction on the surface of the float glass 10, and the coating liquid is applied to the surface of the float glass 10.

[0015] Figure 5 shows the movement of the coating unit from the side. The coating liquid is supplied from the coating liquid tank 12 through the filter 14 and the coating liquid transport pipe 13 to the coating holder 6. A melamine sponge 8 is attached to the coating holder 6 and is impregnated with the coating liquid. When a command is sent from the electric actuator 1, the servo motor 16 is activated, and the rotational force is transmitted to the ball screw 15 by the timing belt 19. The ball screw 15 has the function of converting rotational force into translational force (forward and backward motion), and when the ball screw 15 is activated, the linear block 2 to which the end of the plate 4 is fixed moves on the linear guide rail 3, left and right in this figure, causing the set of electric actuator 1, coating bar 5, coating holder 6 and melamine sponge 8 to move left and right. As a result, the coating liquid impregnated into the melamine sponge 8 is applied to the surface of the substrate (float glass 10 in this case). The pressure applied by the melamine sponge 8 to the substrate can be adjusted by the electric actuator 1 controlling the cylinder 7 for raising and lowering the coating unit (located below the electric actuator 1 and not shown in Figure 5).

[0016] Figure 6 shows a further enlarged view of the coating section. The coating unit's vertical cylinder 7 is connected to the tip of the electric actuator 1 and moves up and down according to a command from the electric actuator 1. The electric actuator 1 is fixed to the plate 4. Holes are provided on both sides of the electric actuator 1 on the plate 4, and the linear shaft 21 supports the coating unit through these holes, and during vertical movement, it can slide via linear bushings provided in the holes. The coating unit's vertical cylinder 7 and the linear shaft 21 are connected to the coating bar 5. The coating bar 5 consists of two parts, upper and lower, and these parts are connected by a mounting bracket 20 and four springs 9. The lower part of the coating bar 5 is reinforced by inserting a fixing bracket 22 into a recess. The coating holder 6 is fitted into the lower recess of the fixing bracket 22. The melamine sponge 8 is inserted into the coating holder 6. The two springs 9 on each side of the mounting bracket 20 can mitigate the impact when the coating unit hits the substrate. Similarly, the application unit is also capable of small pendulum-like movements due to the action of the mounting bracket 20 and the spring 9.

[0017] Figure 7 is an enlarged view of the coating holder 6. It has a U-shaped member with a projection, into which a melamine sponge 8 is inserted, and the coating liquid 17 can be supplied from the coating liquid transport pipe 13 into the resulting space. The projection is inserted into a recess provided in the fixing bracket 22 for fixing.

[0018] The total width of the coating holder 6 and the melamine sponge 8 is matched to the total width of the substrate mounting table of the horizontal coating apparatus of the present invention. The coating liquid is then applied to the entire surface of the substrate by moving the coating holder 6 and the melamine sponge 8 in the direction of the arrow in Figure 5 (the longitudinal direction of the substrate). The melamine sponge 8 may be divided into two or three parts, but it has been confirmed that even if there are small gaps between the melamine sponges, the gaps are filled by the self-leveling function of the applied coating film, resulting in a uniform thickness overall.

[0019] Using the horizontal coating apparatus of the present invention, a coating solution with a viscosity adjusted to 2 to 10 cP (centipoise) can be applied to a substrate placed horizontally on a substrate mounting table using the melamine sponge, and a film thickness determined by the self-leveling effect of the coating solution can be applied. In this case, it is desirable to confirm that the contact angle of the coating solution droplets on the cleaned substrate surface is in the range of 5 to 20° before applying the coating solution. This is because the coating solution spreads uniformly and the adhesion to the substrate increases.

[0020] According to the present invention, a horizontal coating apparatus can be obtained that can easily apply a uniform coating film to a large-area substrate, and this apparatus can be used to apply a coating film with high adhesion that is uniformly spread on the substrate.

[0021] This is a perspective view of the horizontal coating apparatus of the present invention. This is a plan view of the horizontal coating apparatus of the present invention. This is a side view of the horizontal coating apparatus of the present invention. This is a schematic diagram (front view) showing the configuration of the coating section of the horizontal coating apparatus of the present invention. This is a schematic diagram (side view) showing the configuration of the coating section of the horizontal coating apparatus of the present invention. This is an enlarged view of the coating section of the horizontal coating apparatus of the present invention. This is an enlarged view of the coating holder of the horizontal coating apparatus of the present invention.

[0022] The horizontal coating apparatus of the present invention has the configuration and functions described above using Figures 1 to 7, but the configuration, functions, and coating method of the horizontal coating apparatus of the present invention will be described again below based on the following examples.

[0023] A 3mm thick float glass (FL3) measuring 900mm wide x 1200mm long was cleaned using an abrasive (cerium oxide), then brushed with a neutral detergent, rinsed with pure water, dried with an air knife, and then set in the substrate input section of the substrate mounting table of the horizontal coating machine.

[0024] The horizontal coating apparatus of the present invention has the function of applying a coating solution impregnated into a melamine sponge 8 to the entire surface of glass, and is structured so that the coating speed, coating operation mode (one-way coating or back-and-forth coating), etc. can be set via a touch panel.

[0025] The 3mm thick float glass substrate, placed on the substrate mounting table, was manually transported to its designated position on the transport rollers, positioned against the guide, and then the transport rollers were lowered. Finally, the glass substrate was attached using suction cups to complete the setup process.

[0026] As preparation for coating, the coating liquid 17 was supplied from the coating liquid tank 12 to the coating holder 6, which was fitted with melamine sponges 8, and the holder was left waiting. The total coating width of the horizontal coating device used in this embodiment is 900 mm, but in this embodiment, three rows of 299 mm long melamine sponges were joined together and mounted on the coating holder 6 to make it 900 mm. There was a gap of up to approximately 1.5 mm at the joints of the melamine sponges.

[0027] The coating bar 5, coating holder 6, and melamine sponge 8 were assembled into a single unit as shown in Figures 4 and 6, and reinforced with a mounting bracket 20. The assembled coating unit was then mounted on the coating unit up / down cylinder 7 at the tip of the electric actuator 1. The electric actuator 1 was fixed to the plate 4. It was confirmed that the coating unit up / down cylinder 7 could be freely moved up and down by pushing or pulling the coating unit up by approximately 5 cm in response to a command from the electric actuator 1.

[0028] Next, as shown in Figure 5, it was confirmed that by rotating the servo motor 16 in response to a command from the electric actuator 1, and transmitting the rotational force to the ball screw 15 via the timing belt 19, the ball screw rotates clockwise, causing the linear block 2, to which the end of the plate 4 is fixed, to slide forward on the linear guide rails 3 located on both sides of the coating unit, thereby moving the plate 4, the electric actuator 1 fixed to the plate, and the coating unit attached to the electric actuator 1 via the coating unit's vertical movement cylinder 7 forward.

[0029] Next, the coating unit was returned to the starting point of coating the float glass 10. Then, a command was sent from the electric actuator 1 to the coating unit's vertical cylinder 7 to lower the coating unit, bring it into contact with the surface of the float glass 10, and then press it down with a pressing pressure of 50 N.

[0030] Next, by sending a command from the electric actuator to the servo motor, the coating unit was moved forward along the surface of the float glass 10 from the coating starting point, so that the melamine sponge 8 could apply the coating liquid to the surface of the float glass. The coating was completed when the coating unit stopped moving at the rear end of the float glass 10. The pressure of the melamine sponge 8 against the surface of the float glass 10 was set to 50N, and at this time, the cylinder 7 for moving the coating unit up and down descended 1.0 mm after contacting the surface of the float glass 10. The coating speed (coating unit travel speed) during coating was 100 mm / s, and the coating was performed in one direction.

[0031] The coating condition at the seams of Melamine Sponge 8 showed some discoloration immediately after the sponge was used, due to the low amount of coating liquid. However, after about 20 seconds, the discoloration was no longer noticeable. This is thought to be because the self-leveling effect of the coating liquid worked to make the thickness of the coating film uniform.

[0032] The heat-shielding coating liquid (product name: C5000) used in this embodiment had a viscosity of 7 cP (centipoise). When a droplet of the coating liquid was dropped onto a glass substrate after cleaning, the contact angle after 1 second was 18.4°, but after 28 seconds it became 13.4°, indicating that the wettability of the coating liquid to the glass had improved and the self-leveling effect had progressed.

[0033] Immediately after application, the coating was liquid, but after heating with an infrared heater at 100°C for 10 minutes and then allowing it to air dry for one day, the coating had almost completely hardened. The resulting coating was a transparent, slightly blue heat-shielding glass with no color unevenness or discoloration, and micron-sized sparkling specks caused by dust or foreign matter were hardly noticeable. The light transmittance of the heat-shielding glass coated with this heat-shielding liquid was 0.7% for ultraviolet light transmittance, 79% for infrared light cut rate, and 79% for visible light transmittance. There was almost no variation within the surface, indicating that the coating was applied with a uniform film thickness.

[0034] In this embodiment, the coating solution was applied to the float glass substrate using a melamine sponge. However, for resin substrates that are softer than float glass substrates, a urethane sponge can be used instead of a melamine sponge.

[0035] 1. Electric actuator 2. Linear block 3. Linear guide rail 4. Plate 5. Coating bar 6. Coating holder 7. Cylinder for upper and lowering of coating unit 8. Melamine sponge 9. Spring 10. Substrate (float glass) 11. Glass suction cup with glass transport roller 12. Coating liquid tank 13. Coating liquid transport pipe 14. Filter 15. Ball screw 16. Servo motor 17. Coating liquid 18. Cable carrier (registered trademark) 19. Timing belt 20. Mounting bracket 21. Linear shaft 22. Fixing bracket

Claims

1. The apparatus comprises a substrate mounting table for placing substrates, an electric actuator, a plate, a coating unit, and a transport unit. The coating unit comprises a coating unit vertical cylinder and linear shaft provided at the tip of the electric actuator, and a coating unit attached to the electric actuator via the coating unit vertical cylinder. The coating unit comprises a coating bar, a coating holder, and a melamine sponge. The electric actuator is fixed to the plate, and two linear shafts spaced apart on both sides of the electric actuator pass through holes provided in the plate and are fixed to the coating unit to support it. A horizontal coating apparatus characterized in that the bar and the coating holder are connected via a mounting bracket and a spring, the coating holder is filled with a coating liquid adjusted to a viscosity of 2 to 10 cP (centipoise), the coating liquid impregnates the melamine sponge, the transport unit comprises a servo motor, a ball screw, a timing belt, a linear guide rail, and a linear block, the transport unit moves forward or backward the coating unit, which is attached to the plate and the plate via an electric actuator fixed to the plate and an electric actuator via a cylinder for moving the coating unit up and down, so that the melamine sponge impregnated with the coating liquid moves forward or backward on the surface of the substrate.

2. A coating method using the horizontal coating apparatus described in claim 1, characterized in that a substrate is placed on the substrate placement table, the coating unit is moved downward by lowering the cylinder for vertical movement of the coating unit in response to a command from the electric actuator, the melamine sponge impregnated with a coating liquid adjusted to a viscosity of 2 to 10 cP (centipoise) at the tip of the coating unit is brought into contact with the surface of the substrate, the servo motor is rotated in response to a command from the electric actuator, the rotational force is transmitted to the ball screw via the timing belt, the rotational motion of the ball screw causes the linear block, to which the ends of the plate on the linear guide rails on both sides of the coating unit are fixed, to slide forward or backward, so that the plate, the electric actuator fixed to the plate, and the coating unit attached from the electric actuator via the cylinder for vertical movement of the coating unit move forward or backward on the surface of the substrate, thereby coating the surface of the substrate with the coating liquid impregnated in the melamine sponge.

3. The coating method according to claim 2, wherein the coating liquid is applied to the surface of a substrate placed horizontally on the substrate mounting table using the melamine sponge, and a film thickness determined by the self-leveling effect of the coating liquid is applied.

4. The coating method according to claim 2, wherein, before applying the coating liquid, it is confirmed that the contact angle of the droplets of the coating liquid on the cleaned substrate surface is in the range of 5 to 20°, and then the coating liquid is applied.

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