Horizontal coating device and coating method using the same

Abstract

【Problem】The conventional coating liquid application device has a problem that a uniform coating film of the coating liquid cannot be applied to a large area. 【Solution】A horizontal coating device comprising a substrate placement table, an electric actuator, a plate, a coating unit, and a conveyance unit, and a coating method using the same, wherein the coating unit of the coating unit includes a coating bar, a spring, a coating holder, and a melamine sponge. The coating holder is filled with a coating liquid whose viscosity has been adjusted, and the coating liquid is contained in the melamine sponge. Soak The conveyance unit is a horizontal coating device and a coating method using the same, which can move the coating unit forward or backward by sliding a linear block to which the plate on the linear guide rail is fixed by the movement of a ball screw.

Description

Technical Field

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

Background Art

[0002] There is a need to uniformly coat a thin film for a solar cell, a transparent conductive film, or a heat insulating film on a large-sized glass substrate or resin substrate. 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 film, among those that have been put into practical use so far, there is one in which a low emissivity film (so-called LowE film) is formed on a large-sized substrate using a physical vapor deposition method called sputtering. However, a method of coating and forming a coating liquid on a large-sized substrate has not been put into practical use.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved is that in the conventional coating liquid coating apparatus, 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 widthwise dimension of the coating film formed by the applied coating liquid while facilitating the change in the discharge width. It has a slit nozzle that forms a discharge port consisting of a long slit in the width direction and discharges and applies the coating liquid from the discharge port to the substrate, a drive unit that moves the substrate in the front-rear direction with respect to this slit nozzle, a discharge width changing member that changes the widthwise dimension of the discharge port by moving in the width direction within the slit, and an air supply unit that has an air nozzle for blowing air against the 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 widthwise 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 make the thickness of the coating film applied to the member to be coated a desired thickness. The coater of the coating device has a storage part where the coating liquid is stored, a discharge port for discharging the coating liquid, and a slit-shaped flow path connecting these storage part and the discharge port, and discharges the coating liquid from the discharge port to the substrate. The coating device includes a moving means for moving the coater in a direction parallel to the surface to be coated with respect to the substrate, a pump for supplying the coating liquid to the coater, and a control device. The control device performs control for supplying the coating liquid from the pump to the coater while making the coating liquid in the coater negative pressure during the coating operation of discharging the coating liquid from the discharge port to the substrate while moving the coater. However, in this method, in order to make the thickness of the coating film a desired thickness, it is necessary to perform control for supplying the coating liquid from the pump to the coater while making the coating liquid in the coater negative pressure.

[0008] Patent Document 3 aims to provide a coating apparatus and a coating method capable of forming a thin coating film with a uniform thickness by downward-facing capillary coating of a nozzle so that a constant pressure acts on the bead during coating film formation, and appropriately controlling the supply amount of the coating liquid to the bead at the coating start portion and the coating end portion to maximize the product region with a uniform thickness. The coating apparatus includes a coating device having a coating liquid storage portion, a supply flow path, a discharge port, and a slit-shaped flow path communicating the coating liquid storage portion and the discharge port, a moving means for moving the coating device and the like, a lifting device, and a pressure applying device for applying pressure to the coating liquid in the coating device, and includes a pressure gauge for measuring the pressure in the coating liquid storage portion. The pressure applying device includes a tank, an on-off valve, a pressure actuator, and a pressure control device for controlling the operating pressure of the pressure actuator based on the pressure in the coating liquid storage portion. However, this apparatus requires a complex pressure control device and a pressure actuator.

Means for Solving the Problems

[0009] In order to solve the above-mentioned conventional problems, the present invention includes a substrate mounting table for mounting a substrate, an electric actuator, a plate, a coating portion, and a conveying portion. The coating portion includes a cylinder for moving the coating unit up and down provided at the tip of the electric actuator, a linear shaft, and a coating unit attached from the electric actuator via the cylinder for moving the coating unit up and down. The coating unit is a unit including 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 penetrate holes provided in the plate and are fixed to the coating unit to support the coating unit. The coating bar and the coating holder of the coating unit are coupled 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), and the coating liquid is contained in the melamine sponge. Soakis provided, and the conveying unit includes a servo motor, a ball screw, a timing belt, a linear guide rail, and a linear block. The conveying unit moves the plate, the electric actuator fixed to the plate, and the coating unit attached from the electric actuator via the cylinder for moving the coating unit up and down forward or backward, and includes the coating liquid Soak The horizontal coating device is characterized in that the melamine sponge containing the above is adapted to move forward or backward on the surface of the substrate.

[0010] Furthermore, a second invention of the present application is a coating method using the horizontal coating device, comprising placing a substrate on the substrate placement table, and lowering the coating unit up and down cylinder from the electric actuator to lower the coating unit, and the coating liquid adjusted to a viscosity of 2 to 10 cP (centipoise) at the tip of the coating unit is included Soak bringing the melamine sponge into contact with the surface of the substrate, and then rotating the servo motor according to a command of the electric actuator, transmitting the rotational force to the ball screw via the timing belt, and by the rotational movement of the ball screw, sliding the linear block fixed to the end of the plate on the linear guide rail on both outer sides of the coating unit 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 moving the coating unit up and down move forward or backward on the surface of the substrate, whereby the coating liquid contained in the melamine sponge Soak is applied to the surface of the substrate. This is a coating method characterized by the above.

[0011] The external appearance of the horizontal coating apparatus of the present invention is shown in Fig. 1 (perspective view). 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 also the state before the electric actuator and the cylinder for moving the coating unit up and down are coupled is shown. On the lower side, there is the substrate placement table on which a substrate is placed, and a coating unit for applying a coating liquid to the substrate set on the substrate placement table is visible on the right side. The front and the back are the conveyance unit, and there are a ball screw that converts the rotational motion of the servo motor into a back-and-forth motion and a linear block that moves in conjunction with the ball screw on the linear guide rail. What is visible above the back is a cable bear (registered trademark) for moving the cables of the control system in accordance with the movement of the coating unit.

[0012] The front view of the horizontal coating apparatus of the present invention is shown in Fig. 2. On the left side of the front view, there are the linear guide rail and the linear block of the conveyance unit, and there is a cable bear (registered trademark) that bundles the cables of the control system thereon. On the right side of the front view, there is a conveyance unit including the servo motor, the ball screw, the linear guide rail, and the linear block. The plate is fixed to the linear block at the end. The central coating unit is driven up and down in a direction perpendicular to the paper surface by the conveyance unit to apply a coating liquid to the substrate on the substrate placement table. Under the substrate placement table, a glass conveyance roller and a suction cup for fixing the substrate are provided so that the substrate can be moved manually. Such an arrangement is a so-called gantry type in which the conveyance unit is formed to straddle the coating unit.

[0013] The side view of the horizontal coating apparatus of the present invention is shown in Fig. 3. The substrate placement table moves the substrate by the substrate conveyance roller and fixes the substrate with the suction cup. The substrate can be manually moved back and forth and left and right on the conveyance roller. The coating unit is disposed directly below the electric actuator, but moves left and right in this figure together with the electric actuator by the conveyance unit. The cable bear (registered trademark) also moves in the same manner as the movement of the coating unit.

[0014] FIG. 4 is a schematic diagram for explaining the details of the coating portion. The coating liquid is automatically supplied from a coating liquid tank (not shown) to the coating holder 6 through a coating liquid transport pipe (not shown) by a dispenser (not shown), and is contained in the melamine sponge 8. Soak And the coating liquid is contained SoakThe above-mentioned melamine sponge 8 moves in a direction perpendicular to the substrate surface of the float glass 10, i.e., in a direction perpendicular to the paper plane in this figure, so that the coating liquid is applied 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 with its viscosity adjusted to 2 to 10 cP (centipoise), and is about 2 μm to 5 μm. However, by moving the cylinder 7 for moving the coating unit up and down with the electric actuator 1, the pressing force on the melamine sponge 8 can be changed to adjust the discharge amount of the coating liquid. When it is desired to increase the thickness of the coating film, the cylinder 7 for moving the coating unit up and down is operated to press strongly, and when it is desired to reduce the thickness of the coating film, it is operated to press weakly. Between the coating bar 5 and the coating holder 6 of the coating unit, they are connected by a mounting bracket 20 and a spring 9. The coating unit is supported by linear shafts 21 on both outer sides spaced apart from the electric actuator 1, and can slide smoothly up and down by the action of a linear bush provided at a position where the linear shaft 21 penetrates the plate 4. The linear bush is the thickly shown part in FIG. 4 at the position where it penetrates the plate 4 at the central part of the linear shaft 21. The coating unit is supported by the linear shaft 21 and moves up and down by the cylinder 7 for moving the coating unit up and down, and can move like a pendulum, so that the coating unit (and thus the melamine sponge) is correctly pressed vertically against the substrate. The coating unit moves in the longitudinal direction of the substrate (in the direction perpendicular to the paper plane), and its movement is caused by a signal from the electric actuator 1. The servo motor 16 rotates, and the rotational force is transmitted to the ball screw 15 by a timing belt. By the function of the ball screw 15, the rotational force is converted into a reciprocating motion, and the linear block 2 with the end of the plate 4 fixed moves on the linear guide rail 3, so that finally the coating unit moves in the front-rear direction (in the direction perpendicular to the paper plane), and the melamine sponge 8 moves on the surface of the float glass 10 in the front-rear direction, and the coating liquid is applied to the surface of the float glass 10.

[0015] Figure 5 shows the movement of this coating section as seen 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 the coating liquid is contained Soak therein. When a command is sent from the electric actuator 1, the servo motor 16 operates, and the rotational force is transmitted to the ball screw 15 by the timing belt 19. The ball screw 15 has a function of converting the rotational force into a translational force (forward and backward movement). When the ball screw 15 operates, the linear block 2 with the end of the plate 4 fixed moves left and right on the linear guide rail 3. In this figure, the set of the electric actuator 1, the coating bar 5, the coating holder 6, and the melamine sponge 8 moves left and right. As a result, the coating liquid contained Soak in the melamine sponge 8 is applied to the surface of the substrate (float glass 10 in the case of this figure). The substrate pressing force of the melamine sponge 8 can be adjusted by the electric actuator 1 controlling the coating unit up and down cylinder 7 (below the electric actuator 1 and not shown in Figure 5).

[0016] Figure 6 shows a further enlarged view of the coating section. The up-and-down cylinder 7 for the coating unit is connected to the tip of the electric actuator 1 and moves up and down according to commands from the electric actuator 1. The electric actuator 1 is fixed to the plate 4. Holes are provided on both outer sides of the electric actuator 1 on the plate 4. While supporting the coating unit through the linear shaft 21 passing through these holes, during the up-and-down movement, it can slide through the linear bush provided in the holes. The up-and-down cylinder 7 for the coating unit and the linear shaft 21 are connected to the coating bar 5. The coating bar 5 consists of two upper and lower parts, and the upper and lower parts are connected by the mounting brackets 20 and the four springs 9. The lower part of the coating bar 5 is reinforced by inserting the fixing bracket 22 into the recess. And 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 both sides of the mounting bracket 20 can relieve the impact when the coating unit hits the substrate. Also, due to the action of the mounting bracket 20 and the spring 9, the coating unit can perform a small pendulum movement.

[0017] Figure 7 is an enlarged view of the coating holder 6. It has a shape with protrusions on the U-shaped member, and the melamine sponge 8 is inserted into the U-shaped part so that the coating liquid 17 can be supplied from the coating liquid transport pipe 13 into the formed space. The protrusions are inserted into and fixed to the recesses provided on the fixing bracket 22.

[0018] The total width of the coating holder 6 and the melamine sponge 8 is matched to the total width of the substrate placement table of the horizontal coating device of the present invention. And when the coating holder 6 and the melamine sponge 8 move in the direction of the arrow in Figure 5 (the longitudinal direction of the substrate), the coating liquid is applied to the entire surface of the substrate. Although the melamine sponge 8 may be divided into two or three pieces, even if there is a small gap between the melamine sponges, it has been confirmed that the gap is filled by the self-leveling function of the applied coating film, resulting in a uniform thickness as a whole.

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

Effect of the Invention

[0020] According to the present invention, a horizontal coating device capable of easily applying a uniform coating film on a substrate with a large area can be obtained, and a coating film with a large adhesion that spreads uniformly on the substrate can be applied using this device.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiment for Carrying Out the Invention

[0022] The horizontal coating device of the present invention has the configuration and functions described so far with reference to FIGS. 1 to 7. However, based on the following examples, the configuration, function, and coating method of the horizontal coating device of the present invention will be described again.

Example

[0023] A 3 mm thick float glass (FL3) measuring 900 mm wide and 1200 mm 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 loading section of the substrate mounting table of the horizontal coating device.

[0024] The horizontal coating device of the present invention is a melamine sponge 8. Soak The system has the function of applying the coating liquid to the entire surface of the glass, and the coating speed, coating operation mode (one-way coating or reciprocating coating), etc. can be set from the touch panel.

[0025] The 3 mm thick float glass substrate set on the substrate mounting table was manually transported to a fixed position on the transport rollers, positioned against the guide, and the transport rollers were lowered. The glass substrate was then attached to a suction cup to complete the setting of the glass substrate.

[0026] In preparation for coating, coating liquid 17 was supplied from a coating liquid tank 12 containing the coating liquid to coating holder 6 equipped with melamine sponge 8, and the holder was left in standby. The total coating width of the horizontal coating device used in this example was 900 mm, but in this example, melamine sponges with a length of 299 mm were added to the coating holder 6 in three rows to make it 900 mm. The joints of the melamine sponges had a maximum gap of about 1.5 mm.

[0027] The application bar 5, application holder 6, and melamine sponge 8 were assembled into one unit as shown in Figures 4 and 6, and reinforced with a mounting bracket 20. The application unit assembled in this manner was attached to the application unit up / down movement 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 application unit up / down movement cylinder 7 could freely move the application unit up and down by pushing or pulling up the application unit over a distance of about 5 cm in response to a command from the electric actuator 1.

[0028] Next, as shown in FIG. 5, according to a command from the electric actuator 1, the servo motor 16 is rotated, and the rotational force is transmitted to the ball screw 15 via the timing belt 19. By rotating the ball screw clockwise, the linear guide rail 3 on both outer sides of the coating unit is slid forward by the linear block 2 to which the end of the plate 4 is fixed, thereby confirming that the plate 4, the electric actuator 1 fixed to the plate, and the coating unit attached from the electric actuator 1 via the coating unit up-and-down cylinder 7 move forward.

[0029] Next, after returning the coating unit to the coating start point of the float glass 10, a command is sent from the electric actuator 1 to the coating unit up-and-down cylinder 7 to lower the coating unit, bring it into contact with the surface of the float glass 10, and further press it in with a pressing force of 50 N.

[0030] Next, by sending a command from the electric actuator to the servo motor, the coating unit is run forward on the surface of the float glass 10 from the coating start point of the float glass 10, and the melamine sponge 8 applies the coating liquid to the surface of the float glass 10. The running of the coating unit is stopped at the rear end of the float glass 10 to complete the coating. The pressing force of the melamine sponge 8 against the surface of the float glass 10 was set to 50 N. At this time, the coating unit up-and-down cylinder 7 descended 1.0 mm after coming into contact with the surface of the float glass 10. The coating speed (coating unit running speed) during coating was 100 mm / s, and one-way coating was performed.

[0031] Regarding the coating state at the joint of the melamine sponge 8, immediately after the melamine sponge 8 ran, there was less coating liquid, so there was a slight color difference. However, after about 20 seconds, the color difference became indistinguishable. This is presumably because the self-leveling effect of the coating liquid worked and the thickness of the coating film became uniform.

[0032] The physical property values of the heat-insulating coating liquid (product name: C5000) used in this example were as follows: the viscosity was 7 cP (centipoise). When droplets were dropped after cleaning the glass substrate, the contact angle after 1 second was 18.4°, but it became 13.4° after 28 seconds. It was found that the wettability of the coating liquid to the glass was good and the self-leveling effect was progressing.

[0033] The coating film immediately after coating was in a liquid state. However, after heating with an infrared heater at 100°C for 10 minutes and then allowing natural drying for one day, the coating film was almost cured. The coating state was such that there was no color unevenness or color bleeding, and micron-sized shiny bumps caused by dust or foreign matter were hardly noticeable, resulting in a light blue transparent heat-insulating glass. The light transmittance of the heat-insulating glass coated with this heat-insulating coating liquid was as follows: the ultraviolet transmittance was 0.7%, the infrared cut-off rate was 79%, and the visible light transmittance was 79%. It was found that the coating was performed with a uniform film thickness with almost no in-plane variation.

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

Explanation of Signs

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

Claims

1. The coating unit includes a substrate mounting table on which a substrate is mounted, an electric actuator, a plate, a coating unit, and a transport unit. The coating unit includes a coating unit up / down cylinder and a linear shaft provided at the tip of the electric actuator, and a coating unit attached to the electric actuator via the coating unit up / down cylinder. The coating unit is a unit including a coating bar, a coating holder, and a melamine sponge. The electric actuator is fixed to the plate, and two linear shafts provided at a distance 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. The bar and the coating holder are connected via a mounting bracket and a spring, the coating holder is filled with a coating liquid whose viscosity is adjusted to 2 to 10 cP (centipoise) and the coating liquid is impregnated into the melamine sponge, the transport unit is equipped with a servo motor, a ball screw, a timing belt, a linear guide rail and a linear block, and the transport unit advances or retreats the plate, an electric actuator fixed to the plate, and the coating unit attached from the electric actuator via a cylinder for raising and lowering the coating unit, so that the melamine sponge impregnated with the coating liquid moves forward or backward on the surface of the substrate.

2. 2. A coating method using the horizontal coating apparatus according to claim 1, comprising: placing a substrate on the substrate placement table; lowering the coating unit by moving the coating unit up and down cylinder in response to a command from the electric actuator; bringing the melamine sponge, impregnated with a coating liquid having a viscosity adjusted to 2 to 10 cP (centipoise), at the tip of the coating unit into contact with the substrate surface; rotating the servo motor by a command from the electric actuator; transmitting the rotational force to the ball screw via the timing belt; sliding the linear block, to which the end of the plate on the linear guide rails on both sides of the coating unit is fixed, forward or backward by the rotational motion of the ball screw; and moving the plate, the electric actuator fixed to the plate, and the coating unit attached from the electric actuator via the coating unit up and down cylinder forward or backward over the substrate surface, thereby applying the coating liquid impregnated in the melamine sponge to the substrate surface.

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

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

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