Slot Die Coater

Abstract

The object of the present invention is to provide a slot die coater with an edge coating flow rate uniform design. The slot die coater of the present invention includes an upper die, a lower die, a shim interposed between the upper die and the lower die to define a slot and an outlet, and an insulating coating hole formed vertically through the upper die adjacent to the outlet of the upper die, the shim includes a first manifold for insulating coating formed in a surface of the shim at a position corresponding to the insulating coating hole to form a space for containing an insulating coating liquid supplied through the insulating coating hole, and a slit formed in a surface of the shim and communicating with one end of the first manifold to be able to discharge the insulating coating liquid, the indentation depth MD of the first manifold being greater than the indentation depth LD of the slit.

Description

[Technical field]

[0001] The present invention relates to a slot die coater, and more particularly to a slot die coater that can be used to apply an insulating coating to the periphery of a coating layer pattern.

[0002] This application claims priority to Korean Patent Application No. 10-2022-0094219 filed on July 28, 2022 and Korean Patent Application No. 10-2023-0031435 filed on March 9, 2023, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] Recent technological developments and increasing demand for mobile devices have been remarkable, and as a result, the need for secondary batteries as energy sources has been growing rapidly. Such secondary batteries essentially include an electrode assembly, which is a power generating element. The electrode assembly has a form in which a positive electrode, a separator, and a negative electrode are laminated at least once, and the positive electrode and the negative electrode are manufactured by coating and drying a positive electrode active material slurry and a negative electrode active material slurry on a current collector made of aluminum foil and copper foil, respectively.

[0004] In general, such secondary batteries use lithium-containing cobalt oxide (LiCoO2) with a layered crystal structure, lithium-containing manganese oxide such as LiMnO2 with a layered crystal structure and LiMn2O4 with a spinel crystal structure, and lithium-containing nickel oxide (LiNiO2) as the positive electrode active material. Carbon-based materials are mainly used as the negative electrode active material, and recently, due to the increasing need for high-energy lithium secondary batteries, the mixed use of silicon-based materials and silicon oxide-based materials, which have an effective capacity 10 times or more larger than that of carbon-based materials, is being considered.

[0005] In order to make the charge / discharge characteristics of the secondary battery uniform, the positive electrode active material slurry and the negative electrode active material slurry must be uniformly coated on the current collector, and a slot die coater has been used conventionally for this purpose.

[0006] In electrode active material layer coating using a slot die coater, multiple electrode active material layers may be coated onto one current collector in a strip-like pattern (multi-lane coating). The electrode active material slurry is filled into a manifold formed in a die block and discharged from the discharge port side.

[0007] In the case of the positive electrode active material layer, an insulating coating is further applied to the periphery of the pattern (both sides) (hereinafter referred to as edge coating). In order to make the characteristics of the secondary battery uniform, the width / thickness of the edge coating must be uniform. For edge coating, there are two methods used: sequential coating, which is performed after coating the electrode active material layer, and simultaneous coating, which is performed at the same time as coating the electrode active material layer.

[0008] FIG. 1 shows an example of a configuration of a manufacturing apparatus for conventional sequential coating.

[0009] 1, an electrode active material layer is coated using a slot die coater 10, and edge coating is performed using a mini die 20 on the slot die coater 10. An electrode active material slurry for coating an electrode active material layer is supplied to the slot die coater 10 through a slurry supply unit 15, and an insulating coating liquid for edge coating is supplied to the mini die 20 through an insulating coating liquid supply unit 25.

[0010] The slurry supply unit 15 includes a tank 15a for storing the electrode active material slurry, a pipe 15b connecting the tank 15a and the slot die coater 10, and a pump and a valve 15c arranged in the pipe 15b for adjusting the supply amount and on / off of the electrode active material slurry. Similarly, the insulating coating liquid supply unit 25 includes a tank 25a for storing the insulating coating liquid, a pipe 25b connecting the tank 25a and the mini-die 20, and a pump and a valve 25c arranged in the pipe 25b for adjusting the supply amount and on / off of the insulating coating liquid.

[0011] In such an apparatus configuration, the slot die coater 10 and the mini die 20 are configured separately, which has the disadvantages of complicating the configuration of the manufacturing apparatus and lengthening the operating time required.

[0012] 2 to 4 are diagrams illustrating a conventional slot die coater for simultaneous coating.

[0013] Fig. 2 is a perspective view of a conventional slot die coater 30. Referring to Fig. 2, the slot die coater 30 includes a lower die 40, a shim 50, and an upper die 60. The shim 50 defines a discharge port 52 between the lower die 40 and the upper die 60.

[0014] Fig. 3 is an exploded perspective view of the slot die coater 30 shown in Fig. 2. Referring to Fig. 3, a manifold 42 capable of receiving the electrode active material slurry and supplying it to the discharge port 52 side is formed in the lower die 40.

[0015] FIG. 4 is a plan view of the slot die coater 30 shown in FIG. 3 with the upper die 60 omitted, looking down on the shim 50 placed on the lower die 40.

[0016] 3 and 4, in simultaneous coating using a slot die coater 30, the electrode active material slurry is fed from the lower die 40 through a slurry injection hole 45 into a manifold 42 and fed to the discharge port 52 side, and an insulating coating liquid is fed from the upper die 60 to perform edge coating. Looking at the shim 50 interposed between the lower die 40 and the upper die 60, a flow path 55 for edge coating is formed. The upper die 60 is formed with an insulating coating hole 62 so that the insulating coating liquid can be fed to the shim 50.

[0017] In the flow path 55 of the shim 50, a hole 55a is formed for receiving the supply of the insulating coating liquid from the insulating coating hole 62, and a line 55b is connected to the hole 55a. In some of the holes 55a, two lines 55b are separated. An enlarged view of a hole 55a with two lines 55b separated is shown in FIG. 4. When the coating width between the edge coatings is narrow or in order to reduce the number of edge coating liquid supply systems, adjacent edges in one feeding line need to be coated multiple times, so the holes 55a at positions other than the ends (sides) are coated with the insulating coating liquid divided into two lines 55b.

[0018] When the insulating coating liquid is divided into two lines 55b for coating, the flow rate must be distributed evenly from the hole 55a to both sides, but there is a phenomenon in which the uniform distribution cannot be achieved due to die block assembly tolerances and other disturbances. In the current structure, the hole diameter of the insulating coating hole 62 is the same as the hole diameter (diameter C) of the hole 55a in the shim 50. If the alignment between the shim 50 and the die block is misaligned even slightly during assembly, the flow rates on both sides will differ due to the difference in the path length between the two lines 55b branching out to both sides, resulting in different widths and thicknesses of the edge coating. The flow rates will also differ as described above if the supply position of the edge coating liquid on the upper die 60 is misaligned due to processing deviations of the shim 50. Summary of the Invention [Problem to be solved by the invention]

[0019] The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a slot die coater to which an edge coating flow rate uniformity design is applied.

[0020] However, the technical problems that the present invention aims to solve are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0021] The slot die coater of the present invention for solving the above-mentioned problems includes an upper die and a lower die, a shim interposed between the upper die and the lower die to define a slot and an outlet, and an insulating coating hole formed vertically through the upper die adjacent to the outlet of the upper die, the shim including a first manifold for insulating coating indented from a surface of the shim at a position corresponding to the insulating coating hole so as to form a space for receiving insulating coating liquid supplied through the insulating coating hole, and a slit indented from a surface of the shim and communicating with one end of the first manifold so as to be able to discharge the insulating coating liquid, and the indentation depth MD of the first manifold is greater than the indentation depth LD of the slit.

[0022] The slits may be formed separately on both sides of the first manifold.

[0023] A projected area of ​​the first manifold on the surface of the shim may be larger than a projected area of ​​the holes for the insulating coating on the surface of the shim.

[0024] The indentation depth of the first manifold may be greater than or equal to ½ the thickness of the shim.

[0025] The first manifold may be a hole through the shim.

[0026] The slot die coater may further include a second manifold for insulating coating formed indented into at least one of the upper die and the lower die at a position corresponding to the first manifold.

[0027] It is preferable that the pressure loss when the insulating coating liquid is injected through the insulating coating hole and distributed throughout the first manifold is small, and that the pressure loss when the insulating coating liquid is expelled along the slit is large.

[0028] The projection shape of the first manifold onto the surface of the shim is a rectangle having a width MW perpendicular to the direction in which the insulating coating liquid is discharged and a height MH parallel to the direction in which the insulating coating liquid is discharged, and the width MW of the first manifold may be greater than or equal to the diameter C of the hole for the insulating coating.

[0029] The first manifolds may have the same width MW and height MH.

[0030] The slit may have a constant width LW and may include horizontal and vertical portions in the direction in which the insulating coating liquid is discharged, or may include only horizontal portions, and the width MW of the first manifold may be greater than the width LW of the slit.

[0031] The height MH of the first manifold and the indentation depth MD can be determined so that the ratio of the viscosity of the insulating coating liquid in the first manifold to the viscosity of the insulating coating liquid in the slit is 1 to 4, and the width LW of the slit and the indentation depth LD can be determined.

[0032] The indentation depth MD of the first manifold may be greater than three times the indentation depth LD of the slit.

[0033] The recess depth MD of the first manifold may be greater than four times the recess depth LD of the slit, and the height MH of the first manifold may be greater than 2.5 times and less than 4.5 times the diameter C of the hole for the insulating coating.

[0034] The recess depth MD of the first manifold may be greater than 5 times the recess depth LD of the slit, and the height MH of the first manifold may be greater than 3 times and less than 4.5 times the diameter C of the hole for the insulating coating. Effect of the Invention

[0035] According to the present invention, a slot die coater is provided that employs an edge coating flow uniformity design.

[0036] In a slot die coater according to one aspect of the present invention, an additional first manifold is formed on the shim so that the flow rate of the insulating coating liquid, which is the edge coating liquid, can be stabilized before it is discharged to both sides from the supply position. This allows the flow rate of the insulating coating liquid to be evenly distributed when edge coating is required by separating one line from two lines. Even if assembly tolerances of the die block or other disturbances occur, the first manifold formed on the shim plays a leveling role to ensure even distribution. This solves the problem of different coating widths and thicknesses between the two edge coatings formed by separating the insulating coating liquid from the supply position to both sides.

[0037] According to another aspect of the present invention, a second manifold for introducing insulating coating liquid into the upper die or the lower die can be further formed to maximize the equal flow rate entering both sides. If the second manifold is formed in the upper die or the lower die at a position corresponding to the first manifold formed in the shim, the leveling area can be further increased, further improving the effect of uniform edge coating.

[0038] The following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and serve to facilitate a further understanding of the technical ideas of the present invention as well as the contents of the invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0039] [Figure 1] 1 shows an example of a configuration of a manufacturing apparatus for conventional sequential coating. [Diagram 2] FIG. 1 is a diagram illustrating a conventional slot die coater for simultaneous coating. [Diagram 3] FIG. 1 is a diagram illustrating a conventional slot die coater for simultaneous coating. [Figure 4] FIG. 1 is a diagram illustrating a conventional slot die coater for simultaneous coating. [Diagram 5] FIG. 1 is an exploded cross-sectional view showing a schematic configuration of a slot die coater according to the present invention. [Figure 6] FIG. 2 is a perspective view of a shim that can be provided in a slot die coater according to the present invention. [Figure 7] FIG. 7 is a plan view of the shim shown in FIG. 6. [Figure 8] 8 is a cross-sectional view taken along the line AA' in FIG. 7. [Figure 9] FIG. 2 is a perspective view of another shim that can be provided in the slot die coater according to the present invention. [Figure 10] FIG. 10 is a plan view of the shim shown in FIG. [Figure 11] 11 is a cross-sectional view taken along the line BB' in FIG. 10. [Figure 12] FIG. 2 is a diagram of a shim and an upper die provided in another slot die coater according to the present invention. [Figure 13] FIG. 13 is a bottom view of the upper die shown in FIG. 12. [Figure 14] This shows a state in which a coating layer is formed on a substrate using a slot die coater including the shim shown in Figure 6 or Figure 9. [Figure 15] This shows the relationship between fluid viscosity and shear rate. [Figure 16] FIG. 13 is a diagram showing design factors taken into consideration when designing the first manifold and the slits. [Figure 17] FIG. 13 is a diagram showing design factors taken into consideration when designing the first manifold and the slits. [Figure 18]13 is a graph showing the relationship between the height of the first manifold and the flow rate deviation at various viscosity ratios. [Figure 19] 13 is a graph showing the relationship between the height of the first manifold and the flow rate deviation at various viscosity ratios. [Figure 20] 13 is a graph showing the relationship between the height of the first manifold and the flow rate deviation at various viscosity ratios. [Figure 21] 13 is a graph showing the relationship between the height of the first manifold and the flow rate deviation at various viscosity ratios. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, but are to be construed as being in accordance with the meaning and concept of the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of the term in order to best describe the invention. Therefore, it should be understood that the embodiment described in this specification and the configuration shown in the drawings are merely the most preferred embodiment of the present invention, and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0041] In order to clearly explain the present invention, parts that are not relevant to the explanation are omitted, and the same reference numerals are used throughout the specification for the same or similar components. Note that the size and thickness of each component in the drawings are arbitrarily shown for ease of explanation, and the present invention is not necessarily limited to those shown in the drawings. Note that throughout this specification, when a certain part "includes" a certain component, this does not mean that other components are excluded, but that other components may be further included, unless otherwise specified.

[0042] The slot die coater of the present invention is a device that includes a slot and coats a coating liquid on a substrate through the slot. The "substrate" described below is a current collector, and the "coating liquid" is an electrode active material slurry, and the slot die coater of the present invention is a device that can further apply an insulating coating liquid to the periphery of a coating layer pattern formed by applying the coating liquid, thereby performing edge coating. However, the scope of the present invention is not necessarily limited thereto.

[0043] The slot die coater is provided with a manifold inside the die block to uniformly supply / discharge the electrode active material slurry (leveling). In the present invention, an additional structure is formed in the shim to uniformly supply / discharge the insulating coating liquid for edge coating. Since the leveling function is the same, such a structure is also named a manifold. The additional manifold is basically formed in the shim, and the additional manifold formed in the shim will be called the first manifold for insulating coating. The additional manifold can be further attached to the upper die or the lower die, and will be called the second manifold for insulating coating.

[0044] FIG. 5 is an exploded cross-sectional view that illustrates a schematic configuration of a slot die coater according to the present invention.

[0045] 5, the slot die coater 100 has a shim 130 interposed between an upper die 110 and a lower die 120, and includes a manifold 140 in the lower die 120, into which a coating liquid such as an electrode active material slurry is poured. The manifold 140 is formed to uniformly supply / suck the coating liquid onto a substrate such as a current collector. The manifold 140 may be formed in the upper die 110, or may be formed in both the upper die 110 and the lower die 120.

[0046] The shim 130 is interposed between the upper die 110 and the lower die 120 to define a slot S and an outlet O. The upper die 110 and the lower die 120 are rectangular members whose width in the Y direction perpendicular to the X direction is longer than their length in the X direction in which the outlet O faces. The shim 130 comes into contact with the contact surfaces of the upper die 110 and the lower die 120, and can be assembled between the upper die 110 and the lower die 120 by bolts (not shown) that fasten the upper die 110 and the lower die 120 together.

[0047] The shim 130 is a plate-like member having at least one region cut out and an opening to determine the coating width of the coating layer applied onto the substrate. Here, the opening defines a slot S, and the end of the slot S becomes an outlet O. If there is a single opening, a single coating layer can be formed, and if there are two openings, two coating layers can be formed side by side along the Y direction. The manifold 140 contains the electrode active material slurry supplied from a feed section (not shown), and the electrode active material slurry can be discharged through the outlet O communicating with the slot S to form an electrode active material layer.

[0048] The shim 130 is preferably made of a material having sealing properties since it also functions as a gasket to prevent the coating liquid from leaking into the gap between the die blocks 110 and 120 except for the area where the discharge port O is formed. The shim 130 may be made of, for example, plastic or metal, but the present invention is not limited thereto. The shim 130 may be, for example, a resin sheet such as Teflon (registered trademark) or polyester, or a metal sheet such as copper or aluminum.

[0049] The manifold 140 is connected to a coating liquid supply chamber (not shown) disposed outside by a supply pipe, and receives a supply of the coating liquid so that the coating liquid is introduced into the manifold 140. When the manifold 140 is filled to the brim with the coating liquid, the flow of the coating liquid is guided along the slot S and is discharged to the outside through the discharge port O.

[0050] For example, a rotatable coating roll is disposed in front of the slot die coater 100 (X direction), and the coating roll is rotated to discharge a coating liquid and contact the surface of the substrate while running the substrate to be coated, thereby forming a coating layer. For example, an electrode active material layer can be formed on a current collector.

[0051] Here, the slot die coater 100 is disposed so that the direction (X direction) in which the electrode active material slurry, which is the coating liquid, is discharged is approximately horizontal (approximately ±5°). However, the shape is not limited to the example shown here, and for example, the slot die coater may be configured as a vertical die in which the electrode active material slurry is discharged in the Z direction (upward) perpendicular to both the X direction and the Y direction.

[0052] The slot die coater 100 is configured to be able to further apply an insulating coating liquid to the periphery of the coating layer pattern formed by applying the coating liquid. For example, an insulating coating hole 115 is formed adjacent to the discharge port O of the upper die 110 and vertically penetrating the upper die 110. The shim 130 includes a flow path for the insulating coating liquid so that the insulating coating liquid supplied through the insulating coating hole 115 can be discharged onto the substrate to apply the insulating coating liquid to the periphery of the coating layer.

[0053] Fig. 6 is a perspective view of a shim that can be installed in a slot die coater according to the present invention, Fig. 7 is a plan view of the shim shown in Fig. 6, and Fig. 8 is a cross-sectional view taken along the line A-A' in Fig. 7. Fig. 9 is a perspective view of another shim that can be installed in a slot die coater according to the present invention, Fig. 10 is a plan view of the shim shown in Fig. 9, and Fig. 11 is a cross-sectional view taken along the line B-B' in Fig. 10. Fig. 14 shows a state in which a coating layer has been formed on a substrate by a slot die coater including the shim shown in Fig. 6 or Fig. 9.

[0054] First, referring to FIG. 6, FIG. 7, FIG. 9, and FIG. 10, the shim 130 may include a first portion 131 serving as a base, and at least three second portions 132, 133 extending from the first portion 131. The first portion 131 extends along the Y direction. In this embodiment, the number of the second portions 132, 133 is three, including a side second portion 132 included in the peripheral portions on both sides, and a center second portion 133 included between the side second portions 132. The second portions 132, 133 are connected to the same side of the first portion 131 and extend in the same direction, that is, the X direction, and an opening is defined between the side second portion 132 and the center second portion 133. Such an opening may define a slot S and an outlet O. Such a shim 130 has two openings, so that two coating layers 210, 220 can be simultaneously formed on the substrate 200 side by side in the Y direction, as shown in Fig. 14. To further increase the number of patterns of the coating layers 210, 220 that are simultaneously formed, the shim 130 can include a greater number of center second portions 133.

[0055] The left side second portion 132 includes a flow path 134 so that an insulating coating liquid can be applied to the left peripheral portion of the coating layer 210 formed on the left side to form an edge coating layer 210a. The right side second portion 132 includes a flow path 135 so that an insulating coating liquid can be applied to the right peripheral portion of the coating layer 220 formed on the right side to form an edge coating layer 220a. The center second portion 133 includes a flow path 136 so that an insulating coating liquid can be applied simultaneously to the right peripheral portion of the coating layer 210 formed on the left side and the left peripheral portion of the coating layer 220 formed on the right side to form edge coating layers 210b, 220b.

[0056] In FIG. 14, by slitting based on the cutting line CS, each of the coating layers 210 and 220 can be used to manufacture an electrode assembly. The coating layers 210 and 220 can be negative or positive electrodes depending on the type of electrode active material slurry. After stacking the coating layers 210 and 220 together with the corresponding electrodes and separators, the electrode assembly can be wound from one side around a winding shaft to manufacture a jelly roll type electrode assembly, which can be manufactured into a cylindrical battery. The insulating coating liquid capable of forming the edge coating layers 210a, 210b, 220a, and 220b can include, for example, an inorganic filler such as Al2O3 and a polymer resin.

[0057] The edge coating layers 210a, 210b, 220a, 220b may be formed at the boundary between the coating layers 210, 220 and the uncoated portion of the substrate 200. The edge coating layers 210a, 210b, 220a, 220b may be formed so that at least a portion of the edge coating layers 210, 220 overlaps with the boundary between the coating layers 210, 220 and the uncoated portion. The edge coating layers 210a, 210b, 220a, 220b serve to prevent short-circuiting between the two electrodes of opposite polarity facing each other with a separator interposed therebetween. The edge coating layers 210a, 210b, 220a, 220b may cover the boundary between the coating layers 210, 220 and the uncoated portion to a width of 0.3 mm to 5 mm.

[0058] Returning to Figures 6, 7, 9 and 10, the improved structure of the slot die coater 100 according to the present invention includes a shim 130 that is improved from the conventional one, and is characterized in that each of the channels 134, 135, and 136 of the shim 130 is configured to include a first manifold 137 for insulating coating at the supply position of the insulating coating liquid. The insulating coating liquid can be discharged along the X direction onto the substrate through a slit 138 that communicates with the first manifold 137. The end of each of the channels 134, 135, and 136 forms discharge ports 134a, 135a, and 136a so that the insulating coating liquid flows into the shim 130 and is discharged. The enlarged views in Figures 7 and 10 also show the positions of the holes 115 for insulating coating formed in the upper die 110 for reference.

[0059] The first manifold 137 serves to stabilize the flow rate of the insulating coating liquid before the insulating coating liquid is discharged to the outlets 134a, 135a, and 136a through the respective flow paths 134, 135, and 136. The first manifold 137 is indented from the surface of the shim 130 at a position corresponding to the insulating coating hole 115 so as to form a space for receiving the insulating coating liquid supplied through the insulating coating hole 115 of the upper die 110. Referring to Figures 8 and 11, the indented shape of the first manifold 137 can be seen, and the indentation depth of the first manifold 137 is denoted as MD.

[0060] In this way, in the present invention, by forming the first manifold 137, which is an additional manifold, in the shim 130, even if the positions of the insulating coating hole 115 and the shim 130 are misaligned due to differences in assembly and processing, it is possible to prevent deviation (variation) in the flow rate of the insulating coating liquid discharged through the outlets 134a, 135a, and 136a.

[0061] In particular, in the center second portion 133, slits 138 are formed separated from the first manifold 137 to both sides so that the insulating coating liquid can be simultaneously applied to the right peripheral portion of the coating layer 210 formed on the left side and the left peripheral portion of the coating layer 220 formed on the right side. By forming the first manifold 137, the flow rate entering both sides through the slits 138 can be maximized to be the same.

[0062] The cross-sectional shape of the slit 138 (cross-section along the Z direction) may be a square shape. The slit 138 may have a constant width LW. In the examples shown in Figures 6, 7, 9, and 10, the slit 138 includes only a portion that is horizontal to the direction (X direction) in which the insulating coating liquid is discharged. As another example, the slit 138 may include both a portion that is horizontal and a portion that is vertical to the direction (X direction) in which the insulating coating liquid is discharged.

[0063] The slit 138 is formed in communication with one end of the first manifold 137 in order to discharge the insulating coating liquid from the first manifold 137 to the outlet O side of the shim 130. The slit 138 is also formed as an indentation in the surface of the shim 130. With reference to Figures 8 and 11, the indentation shape of the slit 138 can be seen, and the indentation depth of the slit 138 is represented as LD.

[0064] In forming the first manifold 137, which is an additional manifold, and the slit 138 communicating therewith, as shown in Figures 8 and 11, the indentation depth MD of the first manifold 137 is made larger than the indentation depth LD of the slit 138, thereby maximizing the leveling effect and minimizing the flow rate deviation (MD>LD). In the example of the conventional shim 50 described with reference to Figures 3 and 4, no consideration is given to the indentation depth of the hole 55a and the line 55b.

[0065] In the present invention, the projected area of ​​the first manifold 137 on the surface of the shim 130 is preferably larger than the projected area of ​​the insulating coating hole 115 on the surface of the shim 130. In other words, the first manifold 137 is preferably wider than the insulating coating hole 115 (the area of ​​the part parallel to the wide surface of the die block is larger). In the conventional example described with reference to Figs. 3 and 4, the hole diameter of the insulating coating hole 62 and the hole diameter of the hole 55a in the shim 50 are the same, that is, C. According to the present invention, the first manifold 137 is wider than the insulating coating hole 115. If the hole diameter of the conventional insulating coating hole 62 and the hole diameter of the insulating coating hole 115 of the present invention are the same, the first manifold 137 of the present invention is wider than the conventional hole 55a.

[0066] The shape of the first manifold 137 projected onto the surface of the shim 130 may be a rectangle having a width MW perpendicular to the direction (X direction) in which the insulating coating liquid is discharged and a height MH parallel to the direction (X direction) in which the insulating coating liquid is discharged. In the examples shown in Figs. 6, 7, 9, and 10, the width MW of the first manifold 137 is longer than the height MH, and the slit 138 extends in a straight line along the X direction from the first manifold 137 to the discharge port 135a side. In another example, the width MW and height MH of the first manifold 137 may be the same. In this case, as described above, the slit 138 may include both the portion extending in the Y direction and the portion extending in the X direction of the first manifold 137.

[0067] Preferably, the width MW of the first manifold 137 is equal to or larger than the diameter C of the insulating coating hole 115. Also, the width MW of the first manifold is larger than the width LW of the slit. The first manifold 137 can be basically formed into a hexahedron by recessing the shim 130, and the corners of the hexahedron may be rounded to ensure a smooth flow of the liquid and prevent the generation of vortexes.

[0068] Specifically, the leveling effect can be further improved compared to the conventional art by primarily enlarging the area of ​​first manifold 137 (projected area on the surface of shim 130) to be larger than the area of ​​insulating coating hole 115. Furthermore, if the recess depth MD of first manifold 137 is made larger than the recess depth LD of slit 138, the leveling effect can be maximized.

[0069] In this way, according to the present invention, the shim 130 includes a first manifold 137 for insulating coating formed at a position corresponding to the hole 115 for insulating coating of the upper die 110, and the recess depth MD of the first manifold 137 is made larger than the recess depth LD of the slit 138 so that the flow rate of the insulating coating liquid, which is the edge coating liquid, can be sufficiently stabilized before it is discharged to both sides from the supply position. When edge coating is required by separating one line into two lines, the flow rate of the insulating coating liquid can be evenly distributed. Even if assembly tolerances of the die block or other disturbances occur, the first manifold 137 formed in the shim 130 can be used as a leveling function to ensure uniform distribution. Therefore, the problem of different coating widths and thicknesses of edge coating can be solved.

[0070] In this case, as in the example shown in Figures 6 to 8, the recess depth MD of the first manifold 137 may be formed to a depth of approximately 1 / 2 the thickness d of the shim 130 or more, or as in the example shown in Figures 9 to 11, the first manifold 137 may be formed deep enough to become a hole that completely penetrates the shim 130.

[0071] In other words, in the shim 130 of Figures 6 to 8, the indentation depth MD of the first manifold 137 is smaller than the thickness d of the shim 130, and can be equal to or greater than 1 / 2 of the thickness d of the shim 130. The larger the indentation depth MD of the first manifold 137, the better, and in order to obtain a sufficient leveling effect, the indentation depth MD of the first manifold 137 can be equal to or greater than 1 / 2 of the thickness d of the shim 130. Since the larger the indentation depth MD of the first manifold 137, the better, when the indentation depth MD of the first manifold 137 is maximized as in the shim 130 of Figures 9 to 11, the first manifold 137 can be formed in the shape of a hole penetrating the shim 130.

[0072] In the shim 130 of FIG. 9 to FIG. 11, the insulating coating liquid put into the first manifold 137 must not leak out from the interface between the shim 130 and the lower die 120. In this embodiment, the slot die coater 100 is a horizontal die type. The heavy upper die 110 presses and fastens the shim 130 against the lower die 120, so there is a low risk that the insulating coating liquid may flow between the shim 130 and the lower die 120. The force of the upper die 110 pressing the shim 130 in the direction of gravity can prevent the interfaces between the upper die 110 and the shim 130 and the lower die 120 from floating up, and the insulating coating liquid put into the first manifold 137 can not leak out from the interface between the shim 130 and the lower die 120.

[0073] The smaller the pressure loss when the insulating coating liquid is injected from the insulating coating holes 115 and spreads in the first manifold 137 (i.e., the less there is to prevent the flow of the fluid, the shorter the spreading length, and the wider the cross-sectional area), and the larger the pressure loss when the insulating coating liquid is discharged along the slits 138 formed in communication with the first manifold 137, the better the leveling will be. In other words, focusing on the fact that the pressure loss in the slits 138 has a greater effect on the distribution of the flow rate than the pressure loss in the first manifold 137, a mechanism is set up to make the pressure loss in the first manifold 137 as small as possible and the pressure loss in the slits 138 as large as possible.

[0074] 6 to 11, when the shim 130 of the present invention has a structure having two or more discharge parts (corresponding to the slits 138) in one insulating liquid supply part (corresponding to the insulating coating hole 115), the shim 130 has a manifold and land structure so that the flow rate is uniformly distributed to each discharge part. Here, the manifold refers to the first manifold 137, and the land refers to the slits 138.

[0075] The pressure loss of the land portion is to be as large as possible or maximized compared to the pressure loss in the manifold. To achieve this, the volume of the manifold must be maximized and the volume of the land portion must be minimized. To achieve this, when forming the flow paths 134, 135, 136 including the first manifold 137 and the slit 138 in the shim 130, the indentation depth MD of the first manifold 137 is made larger than the indentation depth LD of the slit 138. The larger the indentation depth MD of the first manifold 137, the better.

[0076] Also, the leveling area and volume are increased by making the width MW of the first manifold 137 equal to or larger than the diameter C of the hole 115 for the insulating coating. Therefore, it is preferable that the thickness of the land portion, i.e., the indentation depth LD of the slit 138 < the indentation depth MD of the first manifold 137. The width MW of the first manifold 137 > the diameter C of the hole 115 for the insulating coating > the width of the land portion, i.e., the width LW of the slit 138.

[0077] Furthermore, a second manifold for insulating coating may be further formed to allow the insulating coating liquid for edge coating to enter the upper die 110 or the lower die 120, so that the flow rates entering both sides can be maximized to be equal.

[0078] 6 to 11, depending on the properties of the insulating coating liquid, there may be cases where the problem is not improved or the improvement is insufficient. In such cases, an improvement can be made by forming an additional manifold for insulating coating in the die block.

[0079] FIG. 12 is a diagram of a shim and an upper die provided in another slot die coater according to the present invention, and FIG. 13 is a bottom view of the upper die shown in FIG.

[0080] 12 and 13, a second manifold 117 is further formed in the upper die 110 at a position corresponding to the first manifold 137 of the shim 130. Holes 115 for insulating coating communicate with the bottom surface of the second manifold 117. The second manifold 117 may have the same area as the first manifold 137 and may be formed in the upper die 110 in a basically hexahedral shape, and each corner constituting the hexahedron may be rounded to ensure a smooth flow of the liquid and prevent the generation of vortexes.

[0081] 6 to 8 is used, the second manifold 117 is formed as a depression in the bottom surface of the upper die 110 so as to abut against the first manifold 137, as shown in the example of Fig. 12. Since the first manifold 137 and the second manifold 117 are in communication with each other, this has the effect of increasing the volume of the first manifold 137.

[0082] 9 to 11, the second manifold 117 may be formed in the upper die 110, as shown in Fig. 12, or may be formed in the lower die 120. The second manifold 117 may be formed in either the upper die 110 or the lower die 120, or may be formed in both the upper die 110 and the lower die 120.

[0083] In this way, another slot die coater of the present invention may further include a second manifold 117 in at least one of the upper die 110 and the lower die 120 at a position corresponding to the first manifold 137. In this way, by forming an additional manifold (second manifold 117) in the upper die 110 or the lower die 120 at a position corresponding to the additional manifold (first manifold 137) formed in the shim 130, the leveling volume can be further increased, and the effect of uniform edge coating can be further improved.

[0084] In this way, if the second manifold 117 for introducing the insulating coating liquid is further formed in the upper die 110 or the lower die 120, the flow rate of the insulating coating liquid that is distributed from the first manifold 137 to both sides through the slits 138 can be maximized to be equal. The variation between the left and right sides can be reduced. In other words, if the second manifold 117 is formed in the upper die 110 or the lower die 120 at a position corresponding to the first manifold 137 formed in the shim 130, the leveling area secured by the first manifold 137 can be further increased, and the effect of making the edge coating uniform can be further improved. On the other hand, it is preferable that the structure of such a shim and the structure of the second manifold can be changed according to the physical properties of the insulating coating liquid used for the edge coating to further improve the uniformity of the edge coating.

[0085] The structure of the first manifold and the slits can be determined by taking into consideration that the flow rate deviation varies depending on the liquid properties of the insulating coating liquid, as described below. Figure 15 shows the relationship between the viscosity of the fluid and the shear rate. With reference to Figure 15, the horizontal axis is the shear rate, and the vertical axis is the viscosity.

[0086] If we assume that a fluid (a body that has a tendency to flow, for example, an object) is made up of multiple flat plates stacked on top of each other, and the topmost plate is pulled to the right by a force of F, the lower plates will follow the topmost plate at different speeds due to friction, with the topmost plate being pulled and the closest plate following faster, and the plate that is relatively the furthest following slowest, and the distribution (gradient) of the speeds that occurs at this time is the shear rate. In other words, it is also called the velocity gradient, and is equivalent to the difference in speed between the movable layer and the fixed layer divided by the distance between the two layers.

[0087] Viscosity is the shear stress divided by the shear rate. Shear stress is the stress due to a shear load, i.e. the internal force acting in reaction to an external force acting parallel to the cross section of an object divided by the cross-sectional area.

[0088] Viscosity is a measure of how viscous something is. High viscosity means that the attractive forces between the molecules in the liquid are stronger, holding them together tighter, and there is more resistance to moving through it.

[0089] If the shear stress is strong, the fluid cannot flow easily, which can be considered to have a high viscosity. For a certain fluid, the longer the distance between the movable layer and the fixed layer, the longer the length of the layer that resists the movable layer, the greater the resistance, and the greater the attractive force between the molecules. If the attractive force between the molecules is relatively small, it should be difficult to follow, so the distance between the movable layer and the fixed layer should not be large. In other words, if the distance between the two layers is large, the viscosity is high. For Newtonian fluids, the shear rate and the shear stress are proportional, so the viscosity always has the same value. However, most fluids are not Newtonian fluids and the viscosity changes. As shown in Figure 15, if the shear rate increases, the viscosity decreases, and if the shear rate decreases, the viscosity increases.

[0090] The insulating coating liquid may or may not be a Newtonian fluid. As a result, when the insulating coating liquid flows from the first manifold 137 to the slit 138, a change in viscosity may occur with a change in shear rate. The difference in viscosity is caused by the liquid property of shear thinning as shown in FIG. 15. Therefore, the first manifold 137 and the slit 138 may be designed in consideration of the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity of the insulating coating liquid in the slit 138.

[0091] 16 and 17 are diagrams showing design factors taken into consideration when designing the first manifold and the slits, and FIG. 17 is a cross-sectional view taken along the line CC' in FIG.

[0092] In the illustrated example, the projected shape of the first manifold 137 is rectangular, and has a width MW and a height MH. The width MW of the first manifold is equal to or greater than the diameter C of the hole for the insulating coating. The slit 138 has a constant width LW, and includes both horizontal and vertical portions in the direction in which the insulating coating liquid is discharged. The width MW of the first manifold 137 is greater than the width LW of the slit 138.

[0093] An example for comparison is the shim 50 shown in Fig. 4. In the conventional shim 50, the diameter of the hole 55a for receiving the supply of insulating coating liquid is the same as the diameter C of the hole for insulating coating. When the horizontal length of the line 55b connected to the hole 55a is LA, the width MW of the first manifold 137 in the shim 130 of the present invention is set to be equal to or less than LA x 2 + C. Structurally, the widths of the shims 50 and 130 are considered to be the same.

[0094] Basically, the shear rate in a space approximately the same as a pipe is proportional to the flow rate, so that the shear rate increases as the flow rate increases. Therefore, when the same fluid flows in a wide space, that is, when the flow rate is low, the shear rate is low and the viscosity is high, and when the same fluid flows in a narrow space, that is, when the flow rate is high, the shear rate is high and the viscosity is low. Therefore, since it is a concept of flow rate, the flow rate differs in the first manifold 137 according to the manifold height MH x indentation depth MD, and in the slit 138 according to the slit 138 width LW x indentation depth LD (the total flow rate is the same). It can be said that the flow rate is proportional to the shear rate, and the flow rate is inversely proportional to the viscosity.

[0095] It is preferable that the height MH of the first manifold 137 and the indentation depth MD are determined, and the width LW of the slit 138 and the indentation depth LD are determined so that the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity of the insulating coating liquid in the slit 138 is 1 to 4. The reason why it is written "so that the viscosity ratio is 1 to 4" is because the shear-thinning viscosity differs for each insulating coating liquid.

[0096] 18 to 21 are graphs showing the relationship between the height of the first manifold and the flow rate deviation at various viscosity ratios. The results obtained by calculating the flow rate deviation by simulation are shown. The flow rate deviation refers to the flow rate deviation between the outlets (see 136a in FIG. 16) of the left and right slits 138 connected to the first manifold 137. Taking into account possible assembly deviations, the left and right flow rate deviations were calculated assuming that the position of the shim 130 and the position of the hole 115 for the insulating coating do not exactly match, but are shifted 1 mm to one side. The diameter C of the hole for the insulating coating is set to 5 mm, and the width MW of the first manifold 137 is set to 5 mm or more. Based on the results of FIG. 18 to FIG. 21, the size of the manifold by the liquid can be determined.

[0097] Figure 18 shows the case where the viscosity ratio is 1. This can be said to correspond to the case where the insulating coating liquid is a Newtonian fluid. The horizontal axis of Figure 18 is the magnitude of MH compared to the reference (Ref.). The Ref. of MH is C. The simulation was performed while increasing MH by 1 time (100%) to 5 times (500%) compared to C. The vertical axis of Figure 18 is the flow rate deviation (%). Figure 18 shows the change in flow rate deviation due to changes in MH at each MD while increasing MD by 1 time (100%) to 10 times (1000%) compared to LD.

[0098] It was assumed that the flow rate deviation is at a satisfactory level if it is equal to or less than a predetermined value, for example, 5% (shown by a dashed line in FIG. 18). When the viscosity ratio is 1, MD being 100% compared to LD (●) is judged to be unsuitable because the flow rate deviation is shown as 5% or more regardless of the magnitude of MH. That is, when MD=LD, it is unsuitable for eliminating the flow rate deviation. For all other embodiments in which MD is 150%-1000% compared to LD, the flow rate deviation is shown as 5% or less. Therefore, it can be seen that, as proposed in the present invention, if MD is made larger than LD, the flow rate deviation can be reduced, and the larger MD is, the further the flow rate deviation can be reduced to 2% or less.

[0099] In particular, the portion indicated by the box in the graph of FIG. 18 is a preferable region in terms of the process window. In this portion, MD>3×LD is satisfied. In addition, in this portion, MH is 250% to 400%. That is, 4×C>MH>2.5×C is satisfied. Thus, when the viscosity ratio is 1, the most preferable design region is MD>3×LD, 4×C>MH>2.5×C. The indentation depth MD of the first manifold 137 may be designed to satisfy MD>3×LD, or the indentation depth of the first manifold 137 and the indentation depth of the second manifold 117 may be designed to have a total depth. As a preferable example, the indentation depth MD of the first manifold is set to be greater than three times the indentation depth LD of the slit 138.

[0100] In this way, when the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity in the slit 138 is 1, the sum of the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 (if the second manifold is included) is made greater than three times the indentation depth LD of the slit 138. When there is no second manifold, the indentation depth MD of the first manifold 137 is made greater than three times the indentation depth LD of the slit 138. Then, when the width MW and height MH of the first manifold 137 are the same as each other, the height MH of the first manifold 137 is made greater than 2.5 times and less than four times the diameter C of the insulating coating hole 115.

[0101] Figure 19 shows the case where the viscosity ratio is 2. The horizontal axis of Figure 19, like Figure 18, is the magnitude of MH. Simulations were performed while increasing MH by 1 time (100%) to 5 times (500%) compared to C. The vertical axis of Figure 19 is the flow rate deviation. Figure 19 also shows the change in flow rate deviation due to the change in MH at each MD while increasing MD by 1 time (100%) to 10 times (1000%) compared to LD.

[0102] Here, it was assumed that a flow rate deviation of 4.5% or less is a satisfactory level. When the viscosity ratio is 2, the flow rate deviation is clearly shown as 4.5% or less from the one (▼) where MD is 400% compared to LD, so it is considered to be preferable for the embodiment where MD is 400% to 1000% compared to LD. In particular, the part shown by the box in the graph of FIG. 19 is a preferable region from the viewpoint of the process window. In this part, while satisfying MD>4×LD, 4.5×C>MH>2.5×C is also satisfied. The indentation depth MD of the first manifold 137 may be designed to satisfy MD>4×LD, or the depth obtained by adding up the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 may be designed.

[0103] In other words, when the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity in the slit 138 is 2, the sum of the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 (if the second manifold is included) is made greater than four times the indentation depth LD of the slit 138. When there is no second manifold, the indentation depth MD of the first manifold 137 is made greater than four times the indentation depth LD of the slit 138. When the width MW and height MH of the first manifold 137 are the same as each other, the height MH of the first manifold 137 is made greater than 2.5 times and less than 4.5 times the diameter C of the insulating coating hole 115.

[0104] Figure 20 shows the case where the viscosity ratio is 3. The horizontal axis of Figure 20 also shows the magnitude of MH. Simulations were performed while increasing MH by 1 time (100%) to 5 times (500%) compared to C. The vertical axis of Figure 20 shows the flow rate deviation. Figure 20 also shows the change in flow rate deviation due to the change in MH at each MD while increasing MD by 1 time (100%) to 10 times (1000%) compared to LD.

[0105] It was assumed that a flow rate deviation of 5% or less is a satisfactory level. When the viscosity ratio is 3, the flow rate deviation is clearly shown as 5% or less from the one where MD is 500% compared to LD (◯), so it is considered to be preferable for the embodiment where MD is 500% to 1000% compared to LD. In particular, the part shown by the box in the graph of FIG. 20 is a preferable region from the viewpoint of the process window. In this part, MD>5×LD is satisfied, and 4.5×C>MH>3×C is also satisfied. In this region, the flow rate deviation is reduced by 50% or more and includes the lowest point of the flow rate deviation. The indentation depth MD of the first manifold 137 may be designed to satisfy MD>5×LD, or the depth obtained by adding up the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 may be designed.

[0106] In other words, when the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity in the slit 138 is 3, the sum of the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 (if the second manifold is included) is made greater than five times the indentation depth LD of the slit 138. When there is no second manifold, the indentation depth MD of the first manifold 137 is made greater than five times the indentation depth LD of the slit 138. When the width MW and height MH of the first manifold 137 are the same as each other, the height MH of the first manifold 137 is made greater than three times the diameter C of the insulating coating hole 115 and less than 4.5 times the diameter C.

[0107] Figure 21 shows the case where the viscosity ratio is 4. The horizontal axis of Figure 21 also shows the magnitude of MH. Simulations were performed while increasing MH by 1 time (100%) to 5 times (500%) compared to C. The vertical axis of Figure 21 shows the flow rate deviation. Figure 21 also shows the change in flow rate deviation due to the change in MH at each MD while increasing MD by 1 time (100%) to 10 times (1000%) compared to LD.

[0108] It was assumed that a flow rate deviation of 5% or less is a satisfactory level. When the viscosity ratio is 4, the flow rate deviation is clearly shown as 5% or less from the one where MD is 800% compared to LD (△), so it is considered to be preferable for the embodiment where MD is 800% to 1000% compared to LD. In particular, the part shown by the box in the graph of FIG. 21 is a preferable region in terms of the process window. In this part, while satisfying MD>5×LD, 4.5×C>MH>3×C is also satisfied. The indentation depth MD of the first manifold 137 may be designed to satisfy MD>5×LD, or the depth obtained by adding up the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 may be designed.

[0109] In other words, when the ratio of the viscosity of the insulating coating liquid in the first manifold 137 to the viscosity in the slit 138 is 4, the combined depth of the indentation depth MD of the first manifold 137 and the indentation depth of the second manifold 117 (if the second manifold is included) is made greater than five times the indentation depth LD of the slit 138. When there is no second manifold, the indentation depth MD of the first manifold 137 is made greater than five times the indentation depth LD of the slit 138. When the width MW and height MH of the first manifold 137 are the same as each other, the height MH of the first manifold 137 is made greater than three times the diameter C of the insulating coating hole 115 and less than 4.5 times the diameter C.

[0110] As is clear from the results of FIG. 18 to FIG. 21, when there is no difference between the viscosity in the slit 138 and the viscosity in the first manifold 137, that is, when the viscosity ratio is 1 as shown in FIG. 18, the effect of the first manifold 137 is extremely outstanding. And, as long as the indentation depth MD of the first manifold 137 is three times or more than the indentation depth LD of the slit 138, it is preferable from the viewpoint of the process window. However, when the difference is four times or more (viscosity in the first manifold 137 / viscosity in the slit 138>4), there is no effect. Therefore, the effect of the first manifold 137 further designed in the shim 130 is exerted for a liquid with a viscosity ratio of 1 to 4. The optimum point differs depending on the viscosity ratio, and the deeper the indentation depth MD of the first manifold 137, the better the effect. Therefore, when the effect is low by forming only the first manifold 137 in the shim 130, it may be necessary to process the second manifold 117 in the die blocks 110 and 120.

[0111] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the scope of the technical concept of the present invention and the scope of the claims. [Explanation of symbols]

[0112] 100: Slot die coater 110: Upper die 115: Hole for insulating coating 117: Second manifold 120: Lower die 130: Sim 134, 135, 136: flow path 134a, 135a, 136a: Discharge port 137: First manifold 138: Slit 140: Manifold

Claims

1. An upper die and a lower die; a shim interposed between the upper die and the lower die to define a slot and a discharge port; a hole for insulating coating formed vertically through the upper die adjacent to the discharge port of the upper die; Including, The shim is a first manifold for insulating coating formed in a recess on a surface of the shim at a position corresponding to the hole for insulating coating so as to form a space for receiving an insulating coating liquid supplied through the hole for insulating coating; a slit formed in a surface of the shim and communicating with one end of the first manifold so as to be capable of discharging the insulating coating liquid; Including, A slot die coater, wherein a recess depth (MD) of the first manifold is greater than a recess depth (LD) of the slit.

2. The slot die coater according to claim 1 , wherein the slit is formed separated on both sides from the first manifold.

3. The slot die coater of claim 1 , wherein a projected area of ​​the first manifold on the surface of the shim is greater than a projected area of ​​the holes for the insulating coating on the surface of the shim.

4. 2. The slot die coater of claim 1, wherein the first manifold has a recess depth (MD) that is equal to or greater than 1 / 2 the thickness of the shim.

5. The slot die coater of claim 1 , wherein the first manifold is a hole through the shim.

6. 2. The slot die coater according to claim 1, further comprising a second manifold for insulating coating formed indented in at least one of the upper die and the lower die at a position corresponding to the first manifold.

7. 2. The slot die coater according to claim 1, wherein a pressure loss when the insulating coating liquid is injected from the insulating coating hole and spreads throughout the first manifold is small, and a pressure loss when the insulating coating liquid is discharged along the slit is large.

8. 2. The slot die coater according to claim 1, wherein a projection shape of the first manifold onto the surface of the shim is a rectangle having a width (MW) perpendicular to a direction in which the insulating coating liquid is discharged and a height (MH) parallel to the direction in which the insulating coating liquid is discharged, and the width (MW) of the first manifold is equal to or greater than a diameter (C) of the hole for insulating coating.

9. 9. The slot die coater of claim 8, wherein the first manifolds have the same width (MW) and height (MH) as each other.

10. 10. The slot die coater according to claim 8 or 9, wherein the slit has a constant width (LW) and includes a horizontal portion and a vertical portion in a direction in which the insulating coating liquid is discharged, or includes only a horizontal portion, and the width (MW) of the first manifold is larger than the width (LW) of the slit.

11. 11. The slot die coater according to claim 10, wherein a height (MH) and a depth (MD) of the first manifold are determined, and a width (LW) and a depth (LD) of the slit are determined so that a ratio of a viscosity of the insulating coating liquid in the first manifold to a viscosity of the insulating coating liquid in the slit is 1 to 4.

12. 12. The slot die coater of claim 11, wherein a concave depth (MD) of the first manifold is greater than three times a concave depth (LD) of the slit.

13. 12. The slot die coater of claim 11, wherein the first manifold has a recess depth (MD) greater than 4 times the slit recess depth (LD), and the first manifold has a height (MH) greater than 2.5 times and less than 4.5 times the insulating coating hole diameter (C).

14. 12. The slot die coater of claim 11, wherein the first manifold indentation depth (MD) is greater than 5 times the slit indentation depth (LD), and the first manifold height (MH) is greater than 3 times and less than 4.5 times the insulating coating hole diameter (C).

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