Coating device

Abstract

The purpose of the present invention is to provide a coating device capable of suppressing formation of dragging of a coating liquid at an end portion of a coating film. Specifically, the coating device comprises: a die having a discharge port for discharging a coating liquid toward a prescribed surface of a substrate being conveyed; and a supply valve capable of switching between an open state in which the coating liquid is supplied to the die and a closed state in which the supply of the coating liquid to the die is stopped. The coating device intermittently supplies the coating liquid to the die to discharge the coating liquid from the die by switching the supply valve between the open state and the closed state, and thus intermittently forms a coating film on the prescribed surface of the substrate. The coating device further comprises a discharge amount adjustment mechanism for adjusting the amount of the coating liquid to be discharged from the discharge port. The discharge amount adjustment mechanism is configured to make an adjustment to reduce the amount of the coating liquid to be discharged from the discharge port before the supply valve switches from the open state to the closed state.

Description

Coating device

[0001] The present invention relates to a coating device that forms a coating film by applying a coating liquid to a substrate.

[0002] A lithium-ion battery forms a coating film by applying a slurry of an electrode material (hereinafter referred to as a coating liquid) to a sheet-shaped substrate such as an aluminum foil or a copper foil that is conveyed in a roll-to-roll manner, and the formed coating film is dried to form a positive electrode and a negative electrode.

[0003] In the manufacturing process of a lithium-ion battery, in order to increase the speed for productivity improvement and reduce the loss of the coating liquid, as shown in FIG. 5, a coating film 911 is intermittently formed on a predetermined surface of a substrate 910. That is, by repeatedly discharging and interrupting the discharge of the coating liquid with respect to a predetermined surface of the substrate 910 during conveyance, a coating film 911 is continuously formed on the predetermined surface of the substrate 910 so that there is a certain interval between each of the coating films 911 in the conveyance direction of the substrate 910.

[0004] As shown in FIG. 5, a coating device used in such a manufacturing process of a lithium-ion battery includes a die 920 having a discharge port 921 for discharging a coating liquid, and a supply mechanism 930 for supplying the coating liquid to the die 920. By supplying the coating liquid to the die 920 by the supply mechanism 930, the coating liquid is discharged from the discharge port 921 toward a predetermined surface of the substrate 910.

[0005] Further, the supply mechanism 930 includes a tank 931 for storing the coating liquid, a supply path 932 connecting the tank 931 and the die 920, and a supply valve 933 that can be switched between an open state for opening the supply path 932 and a closed state for closing the supply path 932. Then, by switching the opening and closing state of the supply valve 933, the supply of the coating liquid to the die 920 and the stop of the supply are repeated, so that the coating liquid is intermittently discharged from the discharge port 921 toward a predetermined surface of the substrate 910 to intermittently form a coating film 911 (for example, Patent Document 1 below).

[0006] Japanese Unexamined Patent Application Publication No. 2014-188449

[0007] ; However, in the above coating device 900, there was a case where dragging of the coating liquid was formed at the end portion of the coating film.

[0008] Specifically, in the coating apparatus 900, the supply of coating liquid to the die 920 is stopped by switching the supply valve 933 from an open state to a closed state, and the pressure inside the die 920 is reduced, causing the coating liquid to be drawn back upstream from the discharge port 921. This is how the coating liquid is drained from the discharge port 921. However, in the coating apparatus 900, a constant amount of coating liquid 11 is continuously supplied to the die 920 until the supply valve 933 is switched from an open state to a closed state. Therefore, even if the supply valve 43 is switched from an open state to a closed state, it is not possible to immediately draw back a sufficient amount of coating liquid upstream from the discharge port 921 to drain the coating liquid from the discharge port 921, resulting in insufficient draining of the coating liquid at the discharge port 921. As a result, as shown in Figures 6(a) and 6(b), there was a problem in which a trail of coating liquid 913, which causes a short circuit in the lithium-ion battery, is formed at the coating end portion 912, which is the end of the coating film 911.

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide a coating apparatus that can suppress the formation of drag of the coating liquid at the end of the coating film.

[0010] The present invention, which solves the above problems, comprises a die having a discharge port for discharging a coating liquid toward a predetermined surface of a conveyed substrate, and a supply valve that can be switched between an open state for supplying a coating liquid to the die and a closed state for stopping the supply of a coating liquid to the die, wherein the coating apparatus intermittently supplies and discharges a coating liquid to the die by switching the open and closed state of the supply valve, thereby intermittently forming a coating film on the predetermined surface of the substrate, and further comprises a discharge volume adjustment mechanism for adjusting the amount of coating liquid discharged from the discharge port, wherein the discharge volume adjustment mechanism adjusts the amount of coating liquid discharged from the discharge port to be small before switching the supply valve from the open state to the closed state.

[0011] According to the above coating apparatus, the discharge volume adjustment mechanism adjusts the amount of coating liquid discharged from the discharge port to be reduced before switching the supply valve from the open state to the closed state. Therefore, when switching the supply valve from the open state to the closed state to drain the coating liquid at the discharge port, the amount of coating liquid that needs to be pulled back upstream from the discharge port can be reduced. This prevents insufficient draining of the coating liquid at the discharge port. Consequently, the formation of coating liquid trails at the end of the coating film can be suppressed.

[0012] Furthermore, the discharge volume adjustment mechanism may have a suck-back mechanism that pulls the coating liquid back upstream from the discharge port, and the suck-back mechanism may be configured to reduce the amount of coating liquid discharged from the discharge port by starting to pull the coating liquid back upstream from the discharge port before switching the supply valve from the open state to the closed state.

[0013] With this configuration, the suck-back mechanism can reduce the amount of coating liquid discharged from the outlet by drawing it back upstream from the outlet. Furthermore, by starting the draw-back of the coating liquid upstream from the outlet before switching the supply valve from the open to the closed state, the amount of coating liquid that needs to be drawn back upstream from the outlet when switching the supply valve from the open to the closed state to drain the coating liquid at the outlet can be reduced.

[0014] Furthermore, the die has a coating channel formed therein that is connected to the discharge port and supplies the coating liquid to the discharge port, and the suck-back mechanism has a suck-back part inserted into the coating channel and a drive unit that moves the suck-back part in and out of the coating channel, and the drive unit may be configured to move the suck-back part out of the coating channel at a first speed before switching the supply valve from the open state to the closed state, and to move the suck-back part out of the coating channel at a second speed faster than the first speed when switching the supply valve from the open state to the closed state.

[0015] With this configuration, the suck-back mechanism adjusts the pressure inside the die and thus the amount of coating liquid discharged from the discharge port by moving the suck-back section, which is inserted into the coating channel by the drive unit, in and out of the coating channel. The drive unit moves the suck-back section out of the coating channel at a first speed before switching the supply valve from the open to the closed state, thereby drawing the coating liquid back into the coating channel from the discharge port and adjusting the amount of coating liquid discharged from the discharge port to be reduced. At the same time, when switching the supply valve from the open to the closed state, the suck-back section is moved out of the coating channel at a second speed faster than the first speed, thereby rapidly drawing the coating liquid back upstream from the discharge port and performing decoupling of the coating liquid at the discharge port. As a result, the amount of coating liquid that needs to be drawn back upstream from the discharge port when decoupling the coating liquid at the discharge port can be reduced, and because the coating liquid can be rapidly drawn back upstream from the discharge port at a position closer to the discharge port than the supply valve, insufficient decoupling of the coating liquid at the discharge port can be further suppressed.

[0016] Furthermore, the coating channel may have a pair of expanding spaces formed to protrude in the width direction, and the suck-back portion may be configured to be inserted into each of the pair of expanding spaces.

[0017] This configuration allows the coating liquid to be drawn back from the discharge port towards each of the pair of enlarged spaces formed to protrude in the width direction. As a result, the amount of coating liquid discharged from the discharge port can be adjusted across the width direction, thereby suppressing the formation of coating liquid trail at the end of the coating film across the width direction.

[0018] Furthermore, the coating channel may be configured to include a manifold, which is a space for storing coating liquid that is long in the width direction, and a slit connecting the manifold and the discharge port, and the pair of enlarged spaces may be formed to protrude from each of the ends of the manifold in the width direction.

[0019] With this configuration, the expanded space is formed to protrude from a manifold that is wider than the slit, making it less likely to obstruct the flow of the coating liquid compared to forming the expanded space within the slit.

[0020] According to the coating apparatus of the present invention, it is possible to suppress the formation of drag of the coating liquid at the end of the coating film.

[0021] This is a schematic diagram of a coating apparatus in one embodiment of the present invention, showing the state in which the coating liquid is being discharged. This is a schematic diagram of a coating apparatus in one embodiment of the present invention, showing the state in which the discharge of the coating liquid is interrupted. This is a diagram for explaining the suck-back mechanism in one embodiment of the present invention, where (a) is a cross-section taken along the line A-A in Figure 1, and (b) is a cross-section taken along the line B-B in Figure 2. This is a diagram for explaining the discharge operation of the coating liquid of the coating apparatus in one embodiment of the present invention, where (a) is a time chart of the operation of the supply valve, recovery valve, and suck-back section, and (b) and (c) show the coating film formed by the coating apparatus. This is a diagram of a conventional coating apparatus. This is a diagram of a coating film formed by a conventional coating apparatus.

[0022] Embodiments of the coating apparatus of the present invention will be described with reference to the drawings. In the following description, the three axes of the Cartesian coordinate system are X, Y, and Z, the horizontal direction is expressed as the X-axis direction and the Y-axis direction, and the direction perpendicular to the XY plane (i.e., the vertical direction) is expressed as the Z-axis direction.

[0023] Figures 1 and 2 are schematic diagrams showing a coating apparatus 100 in one embodiment of the present invention. Figure 1 shows the state in which the coating liquid 11 is being discharged, and Figure 2 shows the state in which the discharge of the coating liquid 11 is interrupted. Figure 3 is a diagram for explaining the suck-back mechanism 51 in one embodiment of the present invention. (a) shows a cross-section taken along the line A-A in Figure 1, and (b) shows a cross-section taken along the line B-B in Figure 2. Figure 4 is a diagram for explaining the discharge operation of the coating liquid 11 of the coating apparatus 100 in one embodiment of the present invention. (a) shows a time chart of the operation of the supply valve, the recovery valve, and the suck-back section, and (b) and (c) show the coating film 12 formed on a predetermined surface of the substrate 1 by the coating apparatus 100. Note that a to i in Figures 4(a) to 4(c) respectively indicate the respective states at the same time. Also, the dashed-dotted arrows in Figure 4(a) indicate the passage of time, and the solid arrows in Figures 4(b) and 4(c) indicate the direction in which the coating liquid 11 is applied to the substrate 1.

[0024] As shown in Figures 1 and 2, the coating apparatus 100 includes a transport mechanism 2 for transporting the substrate 1 and a coating mechanism 3 for applying a coating liquid 11 to a predetermined surface of the substrate 1. The coating mechanism 3 repeatedly applies the coating liquid 11 to the predetermined surface of the substrate 1 while it is being transported by the transport mechanism 2, and then interrupts the application process, thereby intermittently forming a coating film 12. Intermittent formation of the coating film 12 means, as shown in Figure 1, that the coating film 12 is continuously formed on the predetermined surface of the substrate 1 such that there is a certain gap between each coating film 12 formed in the transport direction of the substrate 1.

[0025] The base material 1 is a metal foil that will serve as the electrode plate for a lithium-ion battery. When forming the positive electrode, aluminum foil or the like is used, and when forming the negative electrode, copper foil or the like is used. This base material 1 is a long, strip-shaped sheet and is transported by the transport mechanism 2 so that it passes through each part that makes up the coating apparatus 100.

[0026] The coating liquid 11 is, for example, a slurry obtained by mixing an active material, a binder, and a conductive additive with a solvent, and is used as the material for the electrode plates of a lithium-ion battery (so-called electrode material). When this coating liquid 11 is applied to the substrate 1 by the coating mechanism 3, a coating film 12 is formed. This forms the positive or negative electrode of the lithium-ion battery.

[0027] The transport mechanism 2 is for transporting the substrate 1 and employs a roll-to-roll system in which the substrate 1 is transported by the rotation of multiple rolls. The transport speed of the substrate 1 by this transport mechanism 2 is controlled by a control unit (not shown). This control unit is, for example, a general-purpose computer, and will be treated similarly in the following description. In this embodiment, only the coating roll 21 that guides the substrate 1 to the location where the coating liquid 11 is applied by the coating mechanism 3 is shown. This coating roll 21 is positioned opposite the discharge port 32 of the die 31 of the coating mechanism 3 and holds the substrate 1 from the back side of a predetermined surface of the substrate 1 with a predetermined gripping angle. This makes it possible to transport the substrate 1 while maintaining a constant distance from the discharge port 32 of the die 31.

[0028] The coating mechanism 3 is for intermittently forming a coating film 12 by intermittently applying a coating liquid 11 to a predetermined surface of the substrate 1 being transported by the transport mechanism 2. This coating mechanism 3 includes a die 31 for dispensing the coating liquid 11 and a supply mechanism 4 for supplying the coating liquid 11 to the die 31.

[0029] The die 31 is formed to be elongated in one direction, and is elongated along the width direction (Y-axis direction shown in Figure 1) which is perpendicular to the transport direction of the substrate 1 in the in-plane direction of the substrate 1. The coating roll 21 is positioned such that the rotation axis direction of the coating roll 21 and the longitudinal direction of the die 31 are parallel to the die 31. In the following description, the width direction which is perpendicular to the transport direction of the substrate 1 in the in-plane direction of the substrate 1 will also be referred to as the width direction in the description of the die 31, etc.

[0030] The die 31 has a discharge port 32 for discharging the coating liquid 11 onto a predetermined surface of the substrate 1, a manifold 33 that is long in the width direction and stores the coating liquid 11, and a slit 34 connecting the discharge port 32 and the manifold 33. Specifically, the die 31 is constructed by combining a first divided body 31a having a tapered upstream lip 35 and grooves, and a second divided body 31b having a tapered downstream lip 36 and grooves, with a shim 37 sandwiched between them. The manifold 33 and slit 34 are formed inside, and the discharge port 32 is formed between the upstream lip 35 and the downstream lip 36. The discharge port 32 opens to the same length as the slit 34 in the width direction.

[0031] Furthermore, an inlet port 38 is provided in the center of the die 31 in the width direction. The inlet port 38 is a through-hole connecting the outside of the die 31 to the manifold 33, and the coating liquid 11 is supplied to the manifold 33 through this inlet port 38. The coating liquid 11 supplied to the manifold 33 is then discharged from the discharge port 32 through the slit 34.

[0032] The supply mechanism 4 is for supplying the coating liquid 11 to the die 31. This supply mechanism 4 includes a tank 41 for storing the coating liquid 11, a supply passage 42 connecting the manifold 33 and the tank 41, a supply valve 43 that can be switched between an open state for supplying the coating liquid 11 to the die 31 and a closed state for stopping the supply of the coating liquid 11 to the die 31, a recovery passage 44 connecting the supply passage 42 and the tank 41, a recovery valve 45 that can be switched between an open state for recovering the coating liquid 11 into the tank 41 and a closed state for stopping the recovery of the coating liquid 11 into the tank 41, and a pump (not shown) for sending the coating liquid 11 from the tank 41 toward the die 31.

[0033] The supply channel 42 is a pipe connecting the die 31 and the tank 41, and is connected to the inlet port 38. In other words, the coating liquid 11 pumped from the tank 41 is supplied to the manifold 33 through the supply channel 42 and the inlet port 38.

[0034] The supply valve 43 is a valve that can be switched between an open state, which supplies the coating liquid 11 to the die 31, and a closed state, which stops the supply of the coating liquid 11 to the die 31, and is installed in the middle of the supply passage 42. In other words, the open and closed state is switched by opening and closing the supply passage 42 with the supply valve 43.

[0035] Specifically, the supply valve 43 contains a valve body 43c connected by a shaft 43b to a valve body drive unit 43a (for example, an electric motor or air cylinder), which is a drive source. The valve body drive unit 43a moves the shaft 43b, causing the valve body 43c to open or close the supply passage 42. As a result, as shown in Figure 1, opening the supply passage 42 switches to an open state where the coating liquid 11 is supplied to the die 31, and as shown in Figure 2, closing the supply passage 42 switches to a closed state where the supply of the coating liquid 11 to the die 31 is stopped. The valve body drive unit 43a is controlled by the control unit mentioned above.

[0036] The control unit repeatedly switches the open and closed state of the supply valve 43, thereby intermittently supplying the coating liquid 11 to the die 31 and discharging it from the discharge port 32, and intermittently applying it to a predetermined surface of the substrate 1 being transported by the transport mechanism 2. This allows for the intermittent formation of a coating film 12 on the predetermined surface of the substrate 1.

[0037] The recovery channel 44 is a pipe connecting the tank 41 and the supply channel 42, and is connected to the supply channel 42 via a recovery valve 45 upstream of the supply valve 43. In other words, the coating liquid 11 flowing through the supply channel 42 flows through the recovery valve 45 to the recovery channel 44 and is recovered into the tank 41 through the recovery channel 44.

[0038] The recovery valve 45 is a valve that can be switched between an open state, which allows the coating liquid 11 to be recovered into the tank 41, and a closed state, which stops the recovery of the coating liquid 11 to the tank 41, and is installed between the supply passage 42 and the recovery passage 44. In other words, the open and closed state is switched by opening and closing the passage between the supply passage 42 and the recovery passage 44 using the recovery valve 45.

[0039] Specifically, the recovery valve 45 contains a valve body 45c connected by a shaft 45b to a valve body drive unit 45a (for example, an electric motor or air cylinder), which is the drive source. The valve body drive unit 45a moves the shaft 45b, causing the valve body 45c to open and close the passage between the supply passage 42 and the recovery passage 44. As a result, as shown in Figure 2, opening the passage between the supply passage 42 and the recovery passage 44 switches to an open state, allowing the coating liquid 11 to be collected in the tank 41. As shown in Figure 1, closing the passage between the supply passage 42 and the recovery passage 44 switches to a closed state, stopping the collection of the coating liquid 11 into the tank 41. The valve body drive unit 45a is controlled by the control unit mentioned above.

[0040] Furthermore, as shown in Figure 4(a), the supply mechanism 4 switches the open / closed state of the recovery valve 45 in conjunction with the switch on the open / closed state of the supply valve 43. Specifically, as shown in Figures 1 and 2, when the supply valve 43 opens the supply passage 42, the recovery valve 45 closes the space between the supply passage 42 and the recovery passage 44, and when the supply valve 43 closes the supply passage 42, the recovery valve 45 opens the space between the supply passage 42 and the recovery passage 44. As a result, when switching the supply valve 43 from the open state to the closed state, the coating liquid 11 in the supply passage 42 located upstream of the supply valve 43 can be recovered into the tank 41 through the recovery passage 44. This prevents the pressure in the supply passage 42 located upstream of the supply valve 43 from increasing, and prevents the coating liquid 11 from being excessively supplied to the die 31 when switching the supply valve 43 from the closed state to the open state.

[0041] Furthermore, the supply mechanism 4 reduces the pressure inside the die 31 by moving the valve body 43c by the valve body drive unit 43a when switching the supply valve 43 from the open state to the closed state, thereby drawing the coating liquid 11 back from the discharge port 32 towards the supply passage 42. This ensures that the coating liquid 11 is drained from the discharge port 32.

[0042] Here, the coating device 100 further includes a discharge amount adjustment mechanism 5 for adjusting the amount of the coating liquid 11 discharged from the discharge port 32. By this discharge amount adjustment mechanism 5, before switching the supply valve 43 from the open state to the closed state, the discharge amount of the coating liquid 11 from the discharge port 32 is adjusted to be reduced. That is, the coating device 100 adjusts the discharge amount of the coating liquid 11 from the discharge port 32 to be reduced by the discharge amount adjustment mechanism 5 before switching the supply valve 43 from the open state to the closed state to perform liquid draining of the coating liquid 11 at the discharge port 32, thereby reducing the amount of the coating liquid 11 to be drawn upstream from the discharge port 32 when performing liquid draining of the coating liquid 11 at the discharge port 32.

[0043] Further, the discharge amount adjustment mechanism 5 in the present embodiment has a suck-back mechanism 51 for sucking back the coating liquid 11 from the discharge port 32 to the upstream side. The suck-back mechanism 51 is for adjusting the discharge amount of the coating liquid 11 from the discharge port 32 by changing the volume of the coating flow path and adjusting the pressure in the die 31. Here, the coating flow path refers to the flow path for supplying the coating liquid 11 to the discharge port 32 formed in the die 31. In the present embodiment, an example of changing the volume of the manifold 33 by the suck-back mechanism 51 will be described.

[0044] As shown in FIGS. 3(a) and 3(b), the suck-back mechanism 51 has a pair of suck-back portions 52 inserted from both ends of the manifold 33 in the width direction, and a drive portion 53 for inserting and removing the pair of suck-back portions 52 from the manifold 33. Here, the manifold 33 has a pair of enlarged spaces 39 formed so as to project in the width direction from both ends of the discharge port 32 in the width direction, and the pair of suck-back portions 52 are respectively inserted into the pair of enlarged spaces 39. Then, by inserting and removing the pair of suck-back portions 52 from the pair of enlarged spaces 39 by the drive portion 53, the volume of the manifold 33 is changed to adjust the pressure in the die 31, and the discharge amount of the coating liquid 11 from the discharge port 32 is adjusted.

[0045] The suckback portion 52 has a rod-shaped shaft portion 54 that is formed to be long in one direction, and a resistance portion 55 provided at the tip of the shaft portion 54, and is inserted into the enlarged space 39 from the end of the die 31 in the width direction. Specifically, each of the shaft portions 54 of the pair of suckback portions 52 is inserted into each of the pair of enlarged spaces 39 so as to extend from each of the walls at both ends of the die 31 in the width direction toward the other wall, and the resistance portion 55 is provided at the tip of the shaft portion 54 inserted into the enlarged space 39.

[0046] The resistance portion 55 is composed of a disc portion 55a and a cone portion 55b. The disc portion 55a is formed such that its cross-sectional area in the width direction is larger than the cross-sectional area in the width direction of the shaft portion 54, and is approximately the same size as the cross-sectional area in the width direction of the expansion space 39. Here, "approximately the same size" means that the resistance portion 55 can be moved by the drive unit 62, and that the coating liquid 11 does not leak out to the wall side of the expansion space 39 into which the shaft portion 54 is inserted when the resistance portion 55 moves. The cone portion 55b is formed such that its cross-sectional area in the width direction decreases as it moves in the direction in which the suck-back portion 52 is pushed into the expansion space 39.

[0047] The drive unit 53 is a drive source (for example, an electric motor) for extending and retracting the suck-back section 52 from the manifold 33. This drive unit 53 is connected to the suck-back section 52, and by causing the suck-back section 52 to reciprocate in the longitudinal direction of the shaft section 54, the volume of the manifold 33 is changed.

[0048] Specifically, by moving the drive unit 53 in a direction to extract the sack-back portion 52 from the expansion space 39, the volume of the manifold 33 is increased to reduce the pressure in the die 31. By moving the drive unit 53 in a direction to push the sack-back portion 52 into the expansion space 39, the volume of the manifold 33 is decreased to increase the pressure in the die 31. When the pressure in the die 31 is reduced, the coating liquid 11 is drawn back upstream from the discharge port 32, and the discharge amount of the coating liquid 11 from the discharge port 32 can be reduced. When the pressure in the die 31 is increased, the coating liquid 11 is pushed out to the discharge port 32, and the discharge amount of the coating liquid 11 from the discharge port 32 can be increased.

[0049] When the drive unit 53 moves the sack-back portion 52 in a direction to push it into the expansion space 39, as shown in FIG. 3(a), the sack-back portion 52 is moved so that the tip of the resistance portion 55 is located at the same position as the end of the discharge port 32 in the width direction. The position of the sack-back portion 52 after this movement is referred to as the first position in the following description. When the drive unit 53 moves the sack-back portion 52 in a direction to extract it from the expansion space 39, as shown in FIG. 3(b), the sack-back portion 52 is moved so as to extract the sack-back portion 52 from the expansion space 39 while leaving the resistance portion 55 in the expansion space 39. The position of the sack-back portion 52 after this movement is referred to as the second position in the following description.

[0050] Furthermore, the suck-back mechanism 51 is configured to start pulling back the coating liquid 11 from the discharge port 32 to the upstream side before switching the supply valve 43 from the open state to the closed state. Specifically, as shown in Figure 4(a), before switching the supply valve 43 from the open state to the closed state, the suck-back mechanism 51 increases the volume of the manifold 33, reduces the pressure inside the die 31, and pulls the coating liquid 11 back from the discharge port 32 to the upstream side. This reduces the amount of coating liquid 11 discharged from the discharge port 32 before switching the supply valve 43 from the open state to the closed state to drain the coating liquid 11 from the discharge port 32, thereby reducing the amount of coating liquid 11 that needs to be pulled back from the discharge port 32 to the upstream side when draining the coating liquid 11 from the discharge port 32.

[0051] Furthermore, in this embodiment, the suck-back mechanism 51 is configured such that, before the supply valve 43 is switched from the open state to the closed state, the drive unit 53 moves the suck-back section 52 out of the expansion space 3 at a first speed, and when the supply valve 43 is switched from the open state to the closed state, it moves the suck-back section 52 out of the expansion space 39 at a second speed faster than the first speed.

[0052] Specifically, as shown in Figure 4(a), the suck-back mechanism 51 moves the suck-back section 52 at a first speed to a third position located between the first and second positions by the drive unit 53 before the supply valve 43 is switched from the open to the closed position, thereby pulling the coating liquid 11 back upstream from the discharge port 32 and reducing the amount of coating liquid 11 discharged from the discharge port 32. At the same time, when the supply valve 43 is switched from the open to the closed position, the suck-back section 52 is rapidly moved at a second speed from the third position to the second position, thereby rapidly pulling the coating liquid 11 back upstream from the discharge port 32 and draining the coating liquid 11 from the discharge port 11.

[0053] Furthermore, in this embodiment, the enlarged space 39 is formed such that its cross-sectional area in the width direction is smaller than the cross-sectional area of ​​the manifold 33. Specifically, as shown in Figures 1 and 2, the enlarged space 39 is formed only in the first segment 31a of the first segment 31a, the second segment 31b, and the shim 37 that form the manifold 33, thereby making the cross-sectional area in the width direction smaller than the cross-sectional area of ​​the manifold 33. In this way, since the enlarged space 39 is formed only in the first segment 31a, even if the components other than the first segment 31a that constitute the die 31 are changed, such as by changing the shim 37, the size and shape of the enlarged space 39 will not change.

[0054] The operation of the coating apparatus 100 in this embodiment will be described below.

[0055] In the following explanation, we will begin with the state in which the supply mechanism 4 has not supplied the coating liquid 11 to the die 31, as shown in Figure 4(a), and the die 31 has not discharged the coating liquid 11. That is, we will begin with the state in which the supply valve 43 is closed and the recovery valve 45 is open, as shown in Figure 2. We will assume that the pump is continuously supplying the coating liquid 11 from the tank 41 to the die 31 until the discharge of the coating liquid 11 from the die 31 is completely stopped.

[0056] First, the operation when the discharge of the coating liquid 11 from the die 31 is started will be explained. As shown in Figures 1 and 4(a), the supply mechanism 4 supplies the coating liquid 11 from the tank 41 to the manifold 33 through the supply passage 42 by switching the supply valve 43 from a closed state to an open state and switching the recovery valve 45 from an open state to a closed state. The coating liquid 11 supplied to the manifold 33 is then discharged from the discharge port 32 through the slit 34. As a result, as shown in Figures 4(b) and 4(c), the starting end 13 of the coating film 12 is formed on a predetermined surface of the substrate 1 being transported by the transport mechanism 2. This series of operations when the discharge of the coating liquid 11 from the die 31 is started is also performed when the discharge of the coating liquid 11 is interrupted and then resumed.

[0057] When the discharge of the coating liquid 11 from the die 31 is started, the pair of suck-back sections 52 are in the first position, as shown in Figures 3(a) and 4(a).

[0058] Then, the coating device 100 continues to discharge the coating liquid 11 from the die 31 while maintaining the open and closed states of the supply valve 43 and the recovery valve 45, thereby applying the coating liquid 11 to a predetermined surface of the substrate 1 being transported by the transport mechanism 2, as shown in Figures 4(b) and 4(c), to form a coating film 12.

[0059] Next, the operation when the discharge of the coating liquid 11 from the die 31 is interrupted will be explained. As shown in Figures 2 and 4(a), the supply mechanism 4 stops the supply of the coating liquid 11 to the manifold 33 by switching the supply valve 43 from the open state to the closed state and the recovery valve 45 from the closed state to the open state, thereby interrupting the discharge of the coating liquid 11 from the die 31 and draining the coating liquid 11 at the discharge port 32.

[0060] Here, as shown in Figure 4(a), the suck-back mechanism 51 reduces the amount of coating liquid 11 discharged from the discharge port 32 by moving the suck-back section 52 from the first position to the third position at a first speed using the drive unit 53 before switching the supply valve 43 from the open state to the closed state, thereby drawing the coating liquid 11 upstream from the discharge port 32. Then, as shown in Figure 4(a), when switching the supply valve 43 from the open state to the closed state, the suck-back mechanism 51 rapidly moves the suck-back section 52 from the third position to the second position at a second speed using the drive unit 53, thereby rapidly drawing the coating liquid 11 upstream from the discharge port 32 and draining the coating liquid 11 at the discharge port 32.

[0061] As a result, a coating end portion 14 (see Figures 4(b) and 4(c)) is formed, which is the end portion of the coating film 12, where the dragging of the coating liquid 11 (dragging 913 shown in Figures 6(a) and 6(b)) is suppressed.

[0062] Specifically, in this embodiment, the suck-back mechanism 51 adjusts the discharge amount of the coating liquid 11 to be reduced before switching the supply valve 43 from the open state to the closed state, thereby reducing the amount of coating liquid 11 that should be drawn upstream from the discharge port 32 when draining the coating liquid 11 at the discharge port 32. As a result, it is possible to suppress insufficient draining of the coating liquid 11 compared to when draining the coating liquid 11 at the discharge port 32 without adjusting the discharge amount of the coating liquid 11 from the discharge port 32. Therefore, it is possible to suppress the formation of drag of the coating liquid 11 at the end portion 14 of the coating film.

[0063] On the other hand, in this embodiment, the amount of coating liquid 11 discharged from the discharge port 32 is reduced even before the supply valve 43 is switched from the open state to the closed state by the suck-back mechanism 51. This suppresses the formation of drag of the coating liquid 11 at the coating end portion 14, thereby preventing short circuits in lithium-ion batteries. However, as shown in Figures 4(b) and 4(c), the thickness of the coating film 12 near the coating end portion 14 becomes smaller. In contrast, the suck-back mechanism 51 in this embodiment adjusts the amount of coating liquid 11 discharged from the discharge port 32 so that the thickness of the coating film 12 in the range of 1 to 2 mm in front of the coating end portion 14 is about 30 to 70% of the thickness of the coating film 12 outside that range. This makes it possible to suppress the occurrence of drag of the coating liquid 11 at the coating end portion 14 without degrading the performance of the lithium-ion battery.

[0064] Furthermore, in this embodiment, when the suck-back mechanism 51 switches the supply valve 43 from the open state to the closed state, the coating liquid 11 is rapidly pulled back upstream from the discharge port 32 at a position closer to the discharge port 32 than the supply valve 53, thereby draining the coating liquid 11 from the discharge port 32. This makes it possible to further suppress insufficient draining of the coating liquid 11 from the discharge port 32 compared to when draining the coating liquid 11 from the discharge port 32 is performed only by switching the supply valve 43 from the open state to the closed state. Therefore, it is possible to further suppress the formation of drag of the coating liquid 11 at the end portion 14 of the coating film.

[0065] Next, we will explain the operation when resuming the discharge of the coating liquid 11 from the die 31. Note that, apart from the operation of the suck-back mechanism 51, the operation is the same as when starting the discharge of the coating liquid 11 from the die 31, so we will omit the explanation.

[0066] As shown in Figure 4(a), the suck-back mechanism 51 operates to push the suck-back portion 52 into the expanding space 39 so that it returns the suck-back portion 52 from the second position to the first position when the supply valve 43 and the recovery valve 45 are operated. This restarts the discharge of the coating liquid 11 from the die 31, and the starting end portion 13 of the coating film is formed. Then, as shown in Figure 4(a), the coating device 100 repeats the above operation, so that the coating film 11 can be intermittently formed on a predetermined surface of the substrate 1, as shown in Figures 4(b) and 4(c).

[0067] As described above, with the coating apparatus 100 in the above embodiment, the discharge volume adjustment mechanism 5 adjusts the discharge volume of the coating liquid 11 from the discharge port 32 to be reduced before switching the supply valve 43 from the open state to the closed state. This reduces the amount of coating liquid 11 that needs to be drawn upstream from the discharge port 32 when switching the supply valve 43 from the closed state to the open state to drain the coating liquid 11 from the discharge port 32. This prevents insufficient draining of the coating liquid 11 compared to when draining the coating liquid 11 from the discharge port 32 without adjusting the discharge volume of the coating liquid 11 from the discharge port 32. Therefore, it is possible to prevent the formation of drag of the coating liquid 11 at the end portion 14 of the coating film 12.

[0068] Furthermore, in the above embodiment, the drive unit 53 moves the suck-back section 52 out of the coating channel at a first speed before switching the supply valve 43 from the open state to the closed state, thereby drawing the coating liquid 11 back into the coating channel from the discharge port 32 and adjusting the amount of coating liquid 11 discharged from the discharge port 32 to be reduced. At the same time, when switching the supply valve 43 from the open state to the closed state, the drive unit 53 moves the suck-back section 52 out of the coating channel at a second speed faster than the first speed, thereby rapidly drawing the coating liquid 11 back upstream from the discharge port 32 and draining the coating liquid 11 at the discharge port 32. This reduces the amount of coating liquid 11 that needs to be drawn back upstream from the discharge port 32 when draining the coating liquid 11 at the discharge port 32. In addition, because the coating liquid 11 can be rapidly drawn back upstream from the discharge port at a position closer to the discharge port 32 than the supply valve 43, insufficient draining of the coating liquid 11 at the discharge port 32 can be further suppressed.

[0069] Furthermore, in the above embodiment, since the suck-back portion 52 is inserted into each of the pair of enlarged spaces 39 formed to protrude in the width direction, the amount of coating liquid 11 discharged from the discharge port 32 can be adjusted in the width direction by moving the suck-back portion 52 from the first position to the second position and drawing the coating liquid 11 back into each of the pair of enlarged spaces 39. This makes it possible to suppress the formation of drag of the coating liquid 11 at the end portion 14 of the coating film in the width direction.

[0070] Furthermore, in the above embodiment, a pair of expanding spaces 39 are formed to protrude from each of the ends in the width direction of the manifold 33, which is wider than the slit 34, and a suck-back portion 52 is inserted into each of the pair of expanding spaces 39. As a result, the flow of the coating liquid 11 is less likely to be obstructed by the suck-back portion 52 than if a pair of expanding spaces 39 were formed in the slit 34 and the suck-back portion 52 were inserted into that space.

[0071] Furthermore, in the above embodiment, the resistance portion 55 is configured to include a conical portion 55b whose cross-sectional area in the width direction decreases as it moves in the direction of pushing the suck-back portion 52 into the enlarged space 39. This reduces the resistance force on the coating liquid 11 when moving the suck-back portion 52 in the direction of pushing it into the enlarged space 39, thereby reducing the force that pushes the coating liquid 11 toward the discharge port 32. As a result, it is possible to suppress the over-application of the coating liquid 11 when the discharge of the coating liquid 11 from the discharge port 32 is restarted, and thus it is possible to suppress the bulging of the coating film 12 at the starting end 13 of the coating film (bulge 915 in Figure 6(b)).

[0072] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in the above embodiments are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. For example, in the above embodiments, the discharge volume adjustment mechanism 5 has a suck-back mechanism 51, and the discharge volume of the coating liquid 11 from the die 31 has been described as being adjusted by the suck-back mechanism 51, but the invention is not limited to this. For example, a pipe for discharging the coating liquid 11 from the slit 34 and a valve capable of adjusting the flow rate of the coating liquid 11 discharging from the slit 34 through the pipe may be provided, and the discharge volume of the coating liquid 11 from the die 31 may be adjusted by discharging the coating liquid 11 from the slit 34 through the pipe while adjusting the flow rate of the coating liquid 11 with the valve.

[0073] 100 Coating device 1 Substrate 11 Coating liquid 12 Coating film 13 Coating film starting end 14 Coating film ending end 2 Conveying mechanism 21 Coating roll 3 Coating mechanism 31 Die 31a First segment 31b Second segment 32 Discharge port 33 Manifold 34 Slit 35 Upstream lip 36 Downstream lip 37 Shim 38 Inlet port 39 Enlarged space 4 Supply mechanism 41 Tank 42 Supply path 43 Supply valve 43a Valve drive unit 43b Shaft 43c Valve body 44 Recovery path 45 Recovery valve 45a Valve drive unit 45b Shaft 45c Valve body 5 Discharge volume adjustment mechanism 51 Suck-back mechanism 52 Suck-back section 53 Drive unit 54 Shaft 55 Resistance section 55a Disc section 55b Cone section

Claims

1. A coating apparatus comprising: a die having a discharge port for discharging a coating liquid toward a predetermined surface of a substrate being conveyed; a supply valve that can be switched between an open state for supplying a coating liquid to the die and a closed state for stopping the supply of a coating liquid to the die, wherein the coating apparatus intermittently supplies and discharges a coating liquid to the die by switching the open / closed state of the supply valve, thereby intermittently forming a coating film on the predetermined surface of the substrate, further comprising a discharge volume adjustment mechanism for adjusting the amount of coating liquid discharged from the discharge port, wherein the discharge volume adjustment mechanism adjusts the amount of coating liquid discharged from the discharge port to be reduced before switching the supply valve from the open state to the closed state.

2. The coating apparatus according to claim 1, wherein the discharge volume adjustment mechanism has a suck-back mechanism that pulls the coating liquid back upstream from the discharge port, and the suck-back mechanism reduces the amount of coating liquid discharged from the discharge port by starting to pull the coating liquid back upstream from the discharge port before switching the supply valve from the open state to the closed state.

3. The coating apparatus according to claim 2, wherein the die has a coating channel formed therein that is connected to the discharge port and supplies a coating liquid to the discharge port, the suck-back mechanism has a suck-back part inserted into the coating channel and a drive unit that moves the suck-back part in and out of the coating channel, the drive unit moves the suck-back part out of the coating channel at a first speed before switching the supply valve from the open state to the closed state, and moves the suck-back part out of the coating channel at a second speed faster than the first speed when switching the supply valve from the open state to the closed state.

4. The coating apparatus according to claim 3, characterized in that the coating channel has a pair of enlarged spaces formed to protrude in the width direction, and the suck-back portion is inserted into each of the pair of enlarged spaces.

5. The coating apparatus according to claim 4, wherein the coating channel comprises a manifold which is a space for storing coating liquid that is long in the width direction, and a slit connecting the manifold and the discharge port, and the pair of enlarged spaces are formed to protrude from each of the ends of the manifold in the width direction.

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