Slit die

Abstract

The purpose of the present invention is to provide a slit die capable of suppressing the occurrence of unevenness in a discharge amount at the start of discharge of a coating liquid. Specifically, a slit die according to the present invention for solving the above problem comprises: a coating flow path which includes a discharge port that is formed to be long in one direction and discharges a coating liquid, a manifold that stores the coating liquid, and a slit that connects the discharge port and the manifold, the coating flow path supplying the coating liquid to the discharge port; at least one choke bar for adjusting the volume of the coating flow path by being displaced in the gap direction of the slit orthogonal to a slit wall surface that forms the slit and is formed long in the longitudinal direction of the discharge part, the slit die discharging the coating liquid from the discharge port to coat a to-be-coated object with the coating liquid. The origin position of the choke bar when the coating flow path is filled with the coating liquid is set to be a position at which the gap amount between the slit wall surface facing the choke bar in the gap direction and the choke bar is larger than the gap amount between the slit wall surfaces facing each other in the gap direction.

Description

Slit die

[0001] The present invention relates to a slit die for applying a coating liquid to a base material.

[0002] In a coating apparatus for forming positive electrodes and negative electrodes of lithium-ion batteries, a coating film is formed by discharging and applying a slurry (hereinafter referred to as coating liquid), which is obtained by mixing an active material, a binder, and a conductive auxiliary agent with a solvent, onto a conveyed sheet-shaped base material such as aluminum foil or copper foil, and the formed coating film is dried by a drying apparatus.

[0003] Such a coating apparatus is provided with a slit die for discharging the coating liquid. As shown in FIG. 5, the slit die 900 includes a discharge port 910 that is elongated in one direction and discharges the coating liquid, a manifold 920 that stores the coating liquid, and a slit 930 that connects the discharge port 910 and the manifold 920. Then, the coating liquid stored in the manifold 920 is discharged from the discharge port 910 through the slit 930.

[0004] Further, as shown in FIG. 5 and FIG. 6 (a cross-sectional view taken along line B-B in FIG. 5), the slit die 900 is displaced in a direction perpendicular to the slit wall surface 940 elongated in the longitudinal direction of the discharge port 910 forming the slit 930 (hereinafter referred to as the gap direction), and is moved in and out of the slit 930. A plurality of choke bars 950 for adjusting the volume of the slit 930 are arranged side by side in the longitudinal direction. By displacing each choke bar 950 to adjust the volume of the slit 930 along the longitudinal direction, the discharge amount of the coating liquid from the discharge port 910 is adjusted along the longitudinal direction (for example, see Patent Document 1 below).

[0005] Japanese Patent Application Laid-Open No. 2007-044643

[0006] However, the above-mentioned slit die 900 has a problem that uneven discharge amount occurs when starting discharge of the coating liquid.

[0007] Specifically, as shown in Figure 5, the slit 930 in the slit die 900 has a smaller dimension in the gap direction compared to the manifold 920, and the distance from the discharge port 910 is also smaller. Therefore, when filling the manifold 920 with coating liquid and starting to discharge the coating liquid, if the choke bar 950 is inserted into the slit 930, the choke bar 950 will have a significant effect on the flow rate of the coating liquid supplied to the discharge port 910 through the slit 930. In contrast, the slit die 900 is designed so that the origin position of the choke bar 950 when filling the manifold 920 with coating liquid is set such that the outermost surface 951 of the choke bar 950 that is inserted into the slit 930 and the slit wall surface 940 are flush. This reduces the effect of the choke bar 950 on the flow rate of the coating liquid supplied to the discharge port 910 through the slit 930 when the coating liquid is first discharged.

[0008] However, as shown in Figure 6, tilting may occur in each of the choke bars 950 during the assembly of the slit die 900. In this case, the origin position of the choke bar 950 cannot be set so that the outermost surface 951 of the choke bar 950 that is inserted into the slit 930 is flush with the slit wall surface 940, and the tilted choke bar 950 enters the slit 940. As a result, at the start of dispensing the coating liquid, the choke bar 950 has a significant effect on the flow rate of the coating liquid supplied to the discharge port 910 through the slit 930, resulting in the problem of uneven discharge volume.

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide a slit die that can suppress unevenness in the discharge amount at the start of discharge of the coating liquid.

[0010] The present invention, which solves the above problems, includes a discharge port formed to be long in one direction for discharging a coating liquid, a manifold for storing the coating liquid, and a slit connecting the discharge port and the manifold, and comprises a coating channel for supplying the coating liquid to the discharge port, and at least one choke bar for adjusting the volume of the coating channel by being displaced in the gap direction of the slit, which is perpendicular to the slit wall surface that is long in the longitudinal direction of the discharge port forming the slit, and is a slit die for discharging a coating liquid from the discharge port to coat an object to be coated, characterized in that the origin position of the choke bar when filling the coating channel with the coating liquid is set to a position where the amount of the gap between the slit wall surface facing the choke bar in the gap direction and the choke bar is greater than the amount of the gap between the opposing slit wall surfaces in the gap direction.

[0011] According to the above slit die, the origin position where the choke bar begins to displace is set such that the gap between the slit wall surface facing the choke bar and the choke bar in the gap direction perpendicular to the longitudinal direction of the discharge port forming the slit is greater than the gap between opposing slit walls in the gap direction. In other words, the entire choke bar is positioned outside the slit. Therefore, even if the choke bar is tilted, it is possible to prevent the choke bar from entering the slit. This reduces the influence of the choke bar on the flow rate of the coating liquid supplied to the discharge port through the slit. Consequently, unevenness in the discharge amount at the start of coating liquid discharge can be suppressed.

[0012] Furthermore, the coating channel may further include a housing space for housing the choke bar, and the dimensions of the housing space in the gap direction may be larger than the dimensions of the choke bar in the gap direction.

[0013] With this configuration, the dimensions of the accommodating space in the gap direction are larger than the dimensions of the choke bar in the gap direction, making it possible to accommodate the entire choke bar within the accommodating space. This makes it possible to set the origin position of the choke bar so that the entire choke bar is located outside the slit.

[0014] Furthermore, the origin position may be configured such that the flow rate unevenness of the coating liquid applied to the object to be coated, calculated from the dimensions of the choke bar in the flow direction perpendicular to the longitudinal direction of the discharge port in the direction of the slit wall surface, the distance between the slit wall surface and the choke bar in the gap direction, the inclination of the choke bar, the dimensions of the slit in the flow direction, and the dimensions of the slit in the gap direction, is less than or equal to a predetermined value, and the entire choke bar is located outside the slit.

[0015] With this configuration, the origin position of the chalk bar can be set to a position where the flow rate unevenness of the coating liquid applied to the object to be coated is less than or equal to a predetermined value, thereby suppressing the flow rate unevenness of the coating liquid applied to the object to be coated to less than or equal to a predetermined value.

[0016] Furthermore, the predetermined value is preferably 1%.

[0017] Furthermore, the minimum displacement of the chalk bar after setting the origin position of the chalk bar may be set to an amount such that the difference between the flow rate of the coating liquid applied to the object to be coated when the chalk bar is displaced to the origin position of the chalk bar and the flow rate of the coating liquid applied to the object to be coated when the chalk bar is displaced by the minimum amount of the chalk bar is half or less of the predetermined value.

[0018] With this configuration, the minimum displacement of the chalk bar after setting it to the origin position is set to a position where the difference between the flow rate of the coating liquid applied to the object to be coated when the chalk bar is displaced to the origin position and the flow rate of the coating liquid applied to the object to be coated when the chalk bar is displaced to the minimum position is less than or equal to half of the predetermined value. Therefore, after setting the chalk bar to the origin position, it becomes possible to displace the chalk bar in at least two stages within a range where the flow rate unevenness of the coating liquid applied to the object to be coated is less than or equal to a predetermined value. This makes it possible to finely adjust the flow rate of the coating liquid applied to the object to be coated within a range where the flow rate unevenness of the coating liquid applied to the object to be coated is less than or equal to a predetermined value.

[0019] According to the coating apparatus of the present invention, it is possible to suppress unevenness in the discharge amount of the coating liquid at the start of discharge.

[0020] This is a schematic diagram showing a coating apparatus equipped with a slit die according to one embodiment of the present invention. This is a diagram illustrating the slit die according to one embodiment of the present invention. This is a diagram showing an equation for determining the flow rate unevenness of a coating liquid applied to an object to be coated with a predetermined flow rate according to one embodiment of the present invention. This is a diagram showing one variation of a coating apparatus equipped with a slit die according to one embodiment of the present invention. This is a schematic diagram showing a conventional coating apparatus equipped with a slit die. This is a diagram illustrating a conventional slit die.

[0021] 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.

[0022] Figure 1 is a schematic diagram showing a coating apparatus 100 equipped with a slit die 3 in one embodiment of the present invention. Figure 2 is a diagram illustrating the slit die 3 in one embodiment of the present invention, showing a cross-section taken along the line A-A in Figure 1. Figure 3 shows an equation for determining the flow rate unevenness of a coating liquid applied to an object to be coated with a predetermined flow rate in one embodiment of the present invention. Note that in Figure 2, the inclination of the chalk bar 51 is exaggerated for the purpose of facilitating understanding of the invention.

[0023] As shown in Figure 1, the coating apparatus 100 includes a transport mechanism 2 for transporting the substrate 1, a slit die 3 for applying a coating liquid to the substrate 1, and a supply mechanism 4 for supplying the coating liquid to the slit die 3. By supplying the coating liquid to the slit die 3 via the supply mechanism 4, the coating liquid is applied to a predetermined surface of the substrate 1 transported by the transport mechanism 2, forming a coating film. This forms the positive or negative electrode of a lithium-ion battery.

[0024] The base material 1 is a metal foil that serves as the electrode plate for a lithium-ion battery. When it forms the positive electrode, aluminum foil or the like is used, and when it forms 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.

[0025] The coating solution 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 lithium-ion batteries (so-called electrode material). When this coating solution is applied to the substrate 1 from the slit die 3, a coating film is formed.

[0026] The transport mechanism 2 is for continuously transporting the substrate 1 in its longitudinal direction and employs a roll-to-roll system in which the substrate 1 is transported by the rotation of multiple rolls. In this embodiment, only the coating roll 21 that guides the substrate 1 to the location where the coating liquid is applied by the slit die 3 is shown. This coating roll 21 is positioned opposite the discharge port 31 of the slit die 3 and holds the substrate 1 from the back side of a predetermined surface of the substrate 1 with a predetermined gripping angle. This allows the substrate 1 to be transported while maintaining a constant distance from the discharge port 31 of the slit die 3.

[0027] The slit die 3 is used to apply a coating liquid to a predetermined surface of the substrate 1 being transported by the transport mechanism 2, thereby forming a coating film. The slit die 3 is long 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. Here, the aforementioned coating roll 21 is positioned at a predetermined distance from the slit die 3 such that the rotation axis direction of the coating roll 21 and the longitudinal direction of the slit die 3 are parallel. That is, the coating liquid is discharged from the discharge port 31 and applied to the predetermined surface of the substrate 1 while the distance between the substrate 1 guided by the coating roll 21 and the discharge port 31 of the slit die 3 is kept constant. 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 choke bar 51, etc.

[0028] Furthermore, as shown in Figure 1, the slit die 3 is formed to be long in the width direction and includes a discharge port 31 for discharging the coating liquid, and a coating channel 32 for supplying the coating liquid to the discharge port 31. In this embodiment, the coating channel 32 includes a manifold 33 for storing the coating liquid and a slit 34 connecting the discharge port 31 and the manifold 33.

[0029] Specifically, the slit die 31 is constructed by combining a first divided body 3a, which has a tapered upstream lip 35 and a groove formed therein, and a second divided body 3b, which has a tapered downstream lip 36 and a groove formed therein, with a roughly U-shaped shim 37 sandwiched between them. A manifold 33 and a slit 34 are formed inside, and a discharge port 31 is formed between the upstream lip 35 and the downstream lip 36. The discharge port 31 opens to the same length as the slit 34 in the width direction.

[0030] The supply mechanism 4 is for supplying the coating liquid to the slit die 3. This supply mechanism 4 includes a tank 41 for storing the coating liquid, a supply passage 42 connecting the manifold 33 and the tank 41, and a pump (not shown) for transporting the coating liquid. When the coating liquid stored in the tank 41 is supplied to the manifold 33 through the supply passage 42 by the pump, it is discharged from the discharge port 32 through the slit 34. As a result, the coating liquid is applied to a predetermined surface of the substrate 1, and a coating film is formed.

[0031] With this configuration, the coating device 100 can apply the coating liquid to a predetermined surface of the substrate 1 being transported by the transport mechanism 2 using the slit die 3 to form a coating film.

[0032] Furthermore, as shown in Figures 1 and 2, the slit die 3 in this embodiment is further equipped with a volume adjustment mechanism 5 that adjusts the flow rate of the coating liquid applied to a predetermined surface of the substrate 1 (hereinafter referred to as the object to be coated) by adjusting the volume of the coating channel 32.

[0033] The volume adjustment mechanism 5 includes a choke bar 51 that adjusts the volume of the coating channel 32 by displacing it in the direction of the gap in the slit 34 (the Z-axis direction shown in Figure 1), which is perpendicular to the longitudinal direction of the slit wall surface 34a of the discharge port 31 that forms the slit 34, that is, perpendicular to the top surface of the first divided body 3a; a drive unit (for example, a motor) not shown that displaces the choke bar 51; and a shaft unit 52 that connects the choke bar 51 and the drive unit. In the following description, the direction of the gap in the slit 34 perpendicular to the longitudinal direction of the slit wall surface 34a of the discharge port 31 that forms the slit 34 will also be referred to as the gap direction in the description of the choke bar 51, etc.

[0034] The choke bars 51 are used to adjust the volume of the coating channel 32 and are composed of rectangular blocks. Multiple choke bars 51 are arranged in a row in the width direction, and in the example shown in Figure 2, eight choke bars 51 are arranged inside the slit die 3. The drive unit and shaft unit 52 are connected to each choke bar 51, and by operating the respective shaft unit 52 with each drive unit to displace the choke bar 51 in the gap direction, the volume of the coating channel 32 can be adjusted in the width direction. This makes it possible to adjust the flow rate of the coating liquid applied to the object to be coated in the width direction.

[0035] Furthermore, the coating channel 32 further includes a accommodating space 38 for housing the choke bar 51. The accommodating space 38 is formed to protrude from the slit wall surface 34b in the gap direction such that its dimensions in the gap direction are greater than the dimensions of the choke bar 51 in the gap direction. This makes it possible to accommodate the entire choke bar 51 in the accommodating space 38. In this embodiment, the volume of the coating channel 32 is adjusted by the displacement of the choke bar 51 within the accommodating space 38.

[0036] Furthermore, each of the choke bars 51 has a set origin position for when filling the coating channel 32 with coating liquid, that is, when supplying coating liquid to the manifold 33. If each of the choke bars 51 is not tilted, when each of the choke bars 51 is displaced to its origin position, the choke bars 51 will align in a horizontal line.

[0037] It is preferable that the entire choke bar 51 is housed in the housing space 38 without any of the choke bars 51 tilting, but tilting occurs in each of the choke bars 51 during the assembly of the slit die 3. When the choke bars 51 tilt, a part of the tilted choke bar 51 may protrude from the housing space 38 and enter the slit 34. In this case, the dimensions of the slit 34 in the gap direction are smaller than those of the manifold 33, and the distance from the discharge port 31 is also small, so the choke bar 34 that has entered the slit 34 greatly affects the flow rate of the coating liquid supplied to the discharge port 31 through the slit 34, resulting in unevenness in the amount of coating liquid discharged. In particular, when filling the manifold 33 with coating liquid and starting to discharge the coating liquid, unlike after the discharge of the coating liquid has started, it is not possible to check the effect of the choke bar 51 on the flow rate of the coating liquid supplied to the discharge port 31 through the slit 34 and adjust the position of the choke bar 51, so the resulting unevenness in the amount of coating liquid discharged becomes larger.

[0038] In contrast, as shown in Figure 2, in the slit die 3 of this embodiment, the origin position of the choke bar 51 is set to a position where the amount of gap between the slit wall surface 34a facing the choke bar 51 and the choke bar 51 in the gap direction is greater than the amount of gap between the opposing slit wall surface 34a and slit wall surface 34b in the gap direction. That is, the origin position of the choke bar 51 is set so that the entire choke bar 51 is located outside the slit 34.

[0039] The inclination of each choke bar 51 is measured in advance, meaning that the inclination of each choke bar 51 is known. By operating the respective shafts 52 by their respective drive units so that each choke bar 51 is positioned at the origin, the choke bars 51 are displaced collectively to the origin position. This allows the entire choke bar 51 to be positioned outside the slit 34.

[0040] As described above, as shown in Figure 2, even if the choke bar 51 is tilted, the choke bar 51 will not be located inside the slit 34 when the coating liquid is first discharged. Therefore, the influence of the choke bar 51 on the flow rate of the coating liquid supplied to the discharge port 31 through the slit 34 can be reduced. This makes it possible to suppress unevenness in the discharge amount of the coating liquid at the start of discharge.

[0041] Furthermore, the origin position of the choke bar 51 is set such that the part of the choke bar 51 closest to the slit 34 in the gap direction is located outside the slit 34. In this case, the choke bar 51 having the part of the choke bar 51 closest to the slit 34 in the gap direction (hereinafter referred to as the outermost end) is displaced by operating the shaft portion 52 with the drive unit so that the outermost end of the choke bar 51 is located at the origin position. Then, assuming that there is no tilt in each of the choke bars 51, that is, that the outermost end face of each choke bar 51 is parallel to the slit wall surface 34a, the multiple choke bars 51 are simultaneously displaced by operating the respective shaft portions 52 with the respective drive units so that the distance between the outermost end face of the choke bar 51 having the outermost end and the slit wall surface 34a in the gap direction is the same as the distance between the outermost end face of each choke bar 51 without an outermost end and the slit wall surface 34a. As a result, each choke bar 51 without an end is positioned further away from the slit 34 in the gap direction than the choke bar 51 with an end. Therefore, the entire choke bar 51 can be reliably positioned outside the slit 34.

[0042] Furthermore, in the slit die 3 of this embodiment, even if the entire choke bar 51 is housed in the storage space 38 without entering the slit 34, the choke bar 51 will inevitably affect the flow rate of the coating liquid supplied to the discharge port 31 through the slit 34, resulting in some inconsistency in the amount of coating liquid discharged.

[0043] In contrast, in the present embodiment, the origin position of the choke bar 51 is set such that flow rate unevenness with respect to a predetermined flow rate of the coating liquid applied to an object to be coated, which is calculated from the dimension L2 of the choke bar 51 in the flow direction (X-axis direction shown in Fig. 1) orthogonal to the width direction in the inward direction of the slit wall surface 34a, the dimension H2 of the gap between the slit wall surface 34a and the choke bar 51 in the gap direction, the inclination H3 of the choke bar 51, the dimension L1+L3 of the slit 34 in the flow direction, and the dimension H1 of the slit 34 in the gap direction, is equal to or less than a predetermined value, and the entire choke bar 51 is positioned outside the slit 34.

[0044] In the following description, the flow direction orthogonal to the width direction in the inward direction of the slit wall surface 34a is also referred to as the gap direction in the description of the choke bar 51 and the like. Further, the predetermined flow rate of the coating liquid applied to the object to be coated refers to the flow rate of the coating liquid desired to be applied to the object to be coated. Further, the dimension L1+L3 of the slit 34 in the flow direction is the sum of the distance L1 from the manifold 33 to the upstream end of the choke bar 51 in the flow direction and the distance L3 from the downstream end of the choke bar 51 to the discharge port 51 in the flow direction. Further, the inclination H3 of the choke bar refers to the dimension of the gap in the gap direction between the portion closest to the slit 34 and the portion farthest from the slit 34 in the gap direction on the outermost end face of each of the plurality of choke bars 51.

[0045] Specifically, the origin position of the choke bar 51 is obtained by substituting values into each part of the formula in Fig. 3 for obtaining flow rate unevenness with respect to a predetermined flow rate of the coating liquid applied to the object to be coated, as described below. For (ΔQ / Q)offset in the formula of Fig. 3, the value of allowable flow rate unevenness with respect to the predetermined flow rate of the coating liquid applied to the object to be coated is substituted; for H1 in the formula of Fig. 3, the value of the dimension H1 of the slit 34 in the gap direction is substituted; for L1+L3 in the formula of Fig. 3, the value of the dimension L1+L3 of the slit 34 in the flow direction is substituted; for L2 in the formula of Fig. 3, the value of the dimension L2 of the choke bar 51 in the flow direction is substituted; and for ΔH in the formula of Fig. 3, the value of the inclination H3 of the choke bar is substituted. The value of H2 shown in Fig. 3 is calculated from the formula shown in Fig. 3 in which these values are substituted into each part.

[0046] Then, the origin position of the choke bar 51 is set to a position where the dimension value of the gap in the gap direction between the portion of the choke bar 51 closest to the slit 34 in the gap direction and the slit wall surface 34a falls within the value of H2 shown in FIG. 3 calculated by the above calculation, and the entire choke bar 51 is located outside the slit 34. This makes it possible to suppress flow rate unevenness relative to a predetermined flow rate of the coating liquid applied to an object to be coated within an allowable range.

[0047] Here, the predetermined value, which is the allowable range of flow rate unevenness relative to the predetermined flow rate of the coating liquid applied to the object to be coated, is preferably 1% of the predetermined flow rate, which can keep the performance degradation of the lithium-ion battery within the allowable range. In the following description, the predetermined value is set to 1%.

[0048] Further, the minimum displacement amount of the choke bar 51 after setting the origin position of the choke bar 51 is set at a position where the difference between the flow rate of the coating liquid applied to the object to be coated when the choke bar 51 is displaced to the origin position of the choke bar 51 and the flow rate of the coating liquid applied to the object to be coated when the choke bar 51 is displaced to the minimum displacement position of the choke bar 51 is equal to or less than half of 1% which is the aforementioned predetermined value. Note that the minimum displacement amount of the choke bar 51 refers to the resolution of the drive unit that displaces the choke bar 51 in the gap direction.

[0049] Specifically, the minimum displacement amount of the choke bar 51 after setting the origin position of the choke bar 51 is obtained by substituting values into each part of the formula shown in FIG. 3 described above as follows. For (ΔQ / Q)offset in the formula of FIG. 3, substitute a value that is equal to or less than half of 1% which is the predetermined value, said value being the difference from the flow rate of the coating liquid applied to the object to be coated in the displaced state; for H1 in the formula of FIG. 3, substitute the value of dimension H1 of the slit 34 in the gap direction; for L1+L3 in the formula of FIG. 3, substitute the value of dimension L1+L3 of the slit 34 in the flow direction; for L2 in the formula of FIG. 3, substitute dimension L2 of the choke bar 51 in the flow direction; for H2 in the formula of FIG. 3, substitute the value of H2 calculated for obtaining the origin position of the choke bar 51. The value of ΔH shown in FIG. 3 is calculated from the formula shown in FIG. 3 with these values substituted into each part.

[0050] Then, the minimum displacement of the choke bar 51 is set to a position that falls within the value of ΔH shown in Figure 3, which is calculated by the above calculation. As a result, the minimum displacement of the choke bar 51 after setting the origin position of the choke bar 51 is set to a position where the difference between the flow rate of the coating liquid applied to the object to be coated when the choke bar 51 is displaced to the origin position and the flow rate of the coating liquid applied to the object to be coated when the choke bar 51 is displaced to the minimum position is less than or equal to half of the predetermined value of 1%, i.e., 0.5% or less. Therefore, it becomes possible to displace the choke bar 51 in at least two stages within a range where the flow rate unevenness of the coating liquid applied to the object to be coated is 1% or less. Consequently, it becomes possible to finely adjust the flow rate of the coating liquid applied to the object to be coated within a range where the flow rate unevenness of the coating liquid applied to the object to be coated is less than or equal to a predetermined value.

[0051] Furthermore, by individually displacing each of the choke bars 51 with a set minimum displacement amount, the flow rate of the coating liquid applied to the object to be coated can be finely adjusted in the width direction, within a range where the flow rate unevenness of the coating liquid applied to the object to be coated is 1% or less relative to a predetermined flow rate.

[0052] As described above, with the slit die 3 in this embodiment, the origin position where the choke bar 51 begins to displace is set to a position where the gap between the choke bar 51 and the slit wall surface 34a in the gap direction is greater than the gap between the opposing slit wall surfaces 34a and 34b in the gap direction, that is, the entire choke bar 51 is located outside the slit 34. Therefore, even if the choke bar 51 is tilted, it is possible to prevent the choke bar 51 from entering the slit 34, thereby reducing the influence of the choke bar 51 on the flow rate of the coating liquid supplied to the discharge port 31 through the slit 34. This makes it possible to suppress unevenness in the discharge amount at the start of discharge of the coating liquid.

[0053] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of the present invention. For example, in the above embodiments, an example in which multiple choke bars 51 are provided was described, but one may also be provided.

[0054] Furthermore, although the above embodiment describes an example in which the coating channel 32 includes a manifold 33, a slit 34, and a containment space 38, it is not limited to this. For example, as shown in Figure 4, the coating channel may further include an intermediate space 39 between the slit 34 and the containment space 38 in the gap direction, through which the choke bar 51 can be moved in and out. In this case, it is preferable to form the containment space 38 and the intermediate space 39 such that the dimensions of the containment space 38 and the dimensions of the intermediate space 39 in the gap direction are larger than the dimensions of the choke bar 51 in the gap direction.

[0055] Furthermore, although the above embodiment describes an example in which the choke bar 51 is displaced by operating the shaft portion 52 with a drive unit, the invention is not limited to this, and the choke bar 51 may also be displaced manually.

[0056] 100 Coating device 1 Substrate 2 Conveying mechanism 21 Coating roll 3 Slit die 3a First divided part 3b Second divided part 31 Discharge port 32 Coating flow path 33 Manifold 34 Slit 34a Slit wall surface 34b Slit wall surface 35 Upstream lip 36 Downstream lip 37 Shim 38 Storage space 39 Intermediate space 4 Supply mechanism 41 Tank 42 Supply path 5 Volume adjustment mechanism 51 Choke bar 52 Shaft section

Claims

1. A slit die comprising: a discharge port formed to be elongated in one direction for discharging a coating liquid; a manifold for storing the coating liquid; a slit connecting the discharge port and the manifold; a coating channel for supplying the coating liquid to the discharge port; and at least one choke bar for adjusting the volume of the coating channel by being displaced in the direction of the gap between the slits, which is perpendicular to the slit wall surface that is elongated in the longitudinal direction of the discharge port forming the slit; wherein the slit die dispenses a coating liquid from the discharge port to coat an object to be coated, characterized in that the origin position of the choke bar when filling the coating channel with the coating liquid is set to a position where the amount of the gap between the slit wall surface facing the choke bar in the gap direction and the choke bar is greater than the amount of the gap between the opposing slit wall surfaces in the gap direction.

2. The slit die according to claim 1, wherein the coating channel further includes a housing space for housing the choke bar, and the dimensions of the housing space in the gap direction are formed to be larger than the dimensions of the choke bar in the gap direction.

3. The slit die according to claim 1 or 2, characterized in that the origin position is set such that the flow rate unevenness of the coating liquid applied to the object to be coated, calculated from the dimensions of the choke bar in the flow direction perpendicular to the longitudinal direction of the discharge port in the direction of the slit wall surface, the distance between the slit wall surface and the choke bar in the gap direction, the inclination of the choke bar, the dimensions of the slit in the flow direction, and the dimensions of the slit in the gap direction, is less than or equal to a predetermined value, and the entire choke bar is located outside the slit.

4. The slit die according to claim 3, characterized in that the predetermined value is 1%.

5. The slit die according to claim 3, characterized in that the minimum displacement of the choke bar after setting the origin position of the choke bar is set to an amount such that the difference between the flow rate of the coating liquid applied to the object to be coated when the choke bar is displaced to the origin position of the choke bar and the flow rate of the coating liquid applied to the object to be coated when the choke bar is displaced by the minimum displacement amount of the choke bar is less than or equal to half of the predetermined value.

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