Die head

Abstract

A die head 10 includes: an upper component 20; a lower component 30 in which a first manifold portion 32 for storing a first coating liquid is formed; and a plate-shaped first shim 51 disposed between the upper component 20 and the lower component 30 and surrounding the first manifold portion 32 so as to close all directions except one direction, thereby forming a first flow passage 33 through which the first coating liquid flows. A first discharge port 34 for discharging the first coating liquid onto a belt-shaped base material opens on one side of the first flow passage 33 in the one direction. Left and right first inner end portions 51L and 51R of the first shim 51 extend linearly or in a polyline shape from the first manifold portion 32 to the first discharge port 34. A distance between the first inner end portions is narrower on the first discharge port 34 side than on the first manifold portion 32 side, the taper amount is 3.1 mm or more, and a tip release amount on the first discharge port side is 0.1 mm or more and 1.0 mm or less in both vertical and horizontal directions.

Description

Die Head Cross-Reference to Related Applications

[0001] The present disclosure claims the benefit of priority from Japanese Patent Application No. 2025-056680 filed with the Japan Patent Office on March 28, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a die head.

[0003] Patent Document 1 proposes a coating apparatus comprising: a conveyance roller that conveys a belt-shaped base material; and a die head that faces the conveyance roller with a gap therebetween and discharges slurry from a discharge port to apply the slurry onto the conveyed base material, wherein the conveyance roller has a roller central region that is a region at the center in the axial direction thereof, and roller end regions continuous to both sides of the roller central region, the discharge port has a discharge central region facing the roller central region, and discharge end regions facing the roller end regions, and an end gap which is the gap between the roller end region and the discharge end region is wider than a central gap which is the gap between the roller central region and the discharge central region.

[0004] International Publication No. WO 2025 / 047460

[0005] A coating apparatus for applying a coating liquid such as slurry onto a belt-shaped base material includes a conveyance roller that conveys the base material, and a die head that faces the conveyance roller with a gap therebetween and discharges the coating liquid from a discharge port to apply the coating liquid onto the conveyed base material. If there is a difference in the application thickness of the coating liquid discharged onto the base material, that is, the thickness (film thickness) of the coating film formed by the coating liquid, in the width direction of the base material, warpage will occur in the compressed electrode plate due to the difference in film thickness in the width direction, which causes winding misalignment defects in the electrode plate winding process. In addition, portions where the film thickness is insufficient relative to the reference value (both ends in the width direction and the vicinity thereof) are inappropriate as products and thus need to be cut and removed, and it is preferable to minimize the insufficient film thickness portions to suppress a decrease in yield. In view of such circumstances, one object of the present disclosure is to provide a die head capable of uniformizing the film thickness over as wide a range as possible of the entire application width of the coating liquid.

[0006] One aspect of the present disclosure relates to a die head. The die head comprises an upper part, a lower part having a first manifold section for storing a first coating liquid, and a plate-shaped first shim positioned between the upper part and the lower part, surrounding the first manifold section so as to block all directions except one, thereby forming a first flow path through which the first coating liquid flows. A first discharge port for discharging the first coating liquid onto a strip-shaped substrate is opened on the one-direction side of the first flow path. The left and right first inner ends of the first shim are both straight or bent from the first manifold section to the first discharge port. The distance between each of the first inner ends is narrower on the first discharge port side than on the first manifold section side. The taper amount of the first inner ends is 3.1 mm or more. The tip relief amount of the first inner ends on the first discharge port side is 0.1 mm or more and 1.0 mm or less in both the vertical and horizontal directions.

[0007] According to this disclosure, the film thickness is made uniform over a wide area of ​​the coating width, which suppresses winding misalignment defects in the electrode winding process and minimizes areas with insufficient film thickness, thereby suppressing yield reduction. Novel features of the present invention are described in the appended claims, but the present invention, both in terms of its structure and content, along with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings.

[0008] This is a cross-sectional view illustrating the schematic configuration of a die head 10 according to the first embodiment of this disclosure. This is a plan view illustrating a state in which the first shim 51 is placed on the lower part 30 of the die head 10. This is a plan view showing only the first shim 51 of Figure 2. This is an enlarged plan view of the first inner end 51R of the first shim 51 and its surrounding area. This is a plan view illustrating a state in which the first shim 51A, which has a different shape for the first inner end, is placed on the lower part 30. This is a plan view showing only the first shim 51A of Figure 5. This is a cross-sectional view illustrating the schematic configuration of a die head 10B according to the second embodiment of this disclosure.

[0009] An example of a die head relating to this disclosure is described below. However, this disclosure is not limited to the example described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either of the given lower limits and either of the given upper limits can be arbitrarily combined as long as the lower limit is not greater than or equal to the upper limit. Also, in the description of embodiments, terms indicating direction (for example, "up and down" and "left and right") are used as appropriate to facilitate understanding, but these are for illustrative purposes only and do not limit the present invention.

[0010] 1. Die Head (Single Layer) The die head according to this disclosure is a device for applying a coating liquid to a strip-shaped substrate, and is generally referred to as a die coater. Examples of substrates include, but are not limited to, current collectors for batteries, specifically, negative electrode current collectors for lithium-ion secondary batteries. The width of the substrate is assumed to be, for example, about 60 to 140 cm. The type of coating liquid applied to the substrate is not particularly limited. Examples include, but are not limited to, electrode mixture slurry, specifically, negative electrode mixture slurry for lithium-ion secondary batteries. Hereinafter, the coating liquid may also be referred to as the "first coating liquid". When the width of the substrate is 60 cm or more, the film thickness of the coating liquid discharged onto the substrate is generally prone to fluctuation in the width direction of the substrate. However, by using the die head according to this disclosure, such fluctuations in film thickness can be suppressed.

[0011] The die head according to this disclosure comprises an upper component, a lower component, and a first shim positioned between the upper and lower components. This die head can also be described as a single-layer die head capable of applying one type of coating liquid to a strip-shaped substrate. In the following description, a horizontal die head is assumed, but a vertical die head may also be used.

[0012] 1.1 Upper Part The upper part is a component located on the upper side in a horizontal die head. The upper part may constitute approximately half of the die head. The upper part is made of a metal material such as Invar or stainless steel. The upper part may be formed as a whole in the shape of a somewhat flattened rectangular parallelepiped. The lower surface of the upper part may be formed to be substantially flat.

[0013] 1.2 Lower Parts The lower parts are located on the bottom of a horizontal die head. The lower parts constitute roughly the remaining half of the die head after the upper parts have been removed. The lower parts are also made of metal materials such as Invar or stainless steel. The lower parts may also be formed as a somewhat flattened rectangular parallelepiped overall.

[0014] The lower component has a first manifold section formed therein for storing the first coating liquid. The first manifold section may also be formed as a recess on the upper surface of the lower component. The first coating liquid is supplied to the first manifold section from an external first coating liquid supply means. The manifold section is sometimes also referred to as a liquid reservoir.

[0015] 1.3 First Shim The first shim is positioned between the upper and lower parts as described above. The first shim is a plate-shaped member that surrounds the first manifold section in such a way that it blocks all but one direction, thereby forming a first flow channel through which the first coating liquid flows. For example, if both the upper and lower parts are horizontally elongated rectangles in plan view, the first shim surrounds the first manifold section in such a way that it blocks all but one direction, i.e., three directions, thereby forming a wide groove-shaped first flow channel.

[0016] On one side of the first flow path, a first discharge port is opened for discharging the first coating liquid onto a strip-shaped substrate. In other words, the first coating liquid stored in the first manifold flows in the only direction not blocked by the first shim, and the first discharge port is open in this direction.

[0017] 1.4 Shape Characteristics of the First Shim The plan view shape of the first shim may match the outer shapes of the upper and lower parts, except for one direction that is not blocked. Even in the one direction that is not blocked, both ends other than the first discharge port may match the outer shapes of the upper and lower parts. Furthermore, the plan view shape of the portion of the first shim that surrounds the first manifold portion will generally match the plan view shape of the first manifold portion itself. For example, if the plan view shape of the first manifold portion is a rounded rectangular shape, then the portion of the first shim that surrounds the first manifold portion will also be a rounded rectangular shape. The shape characteristics of the first shim are located in the remaining portion excluding these parts, namely the left and right first inner ends described below.

[0018] The left and right first inner ends of the first shim are both straight or bent from the first manifold section to the first discharge port. The distance between each first inner end is narrower on the first discharge port side than on the first manifold section side. For example, each first inner end is formed in a straight line that gradually moves towards the center from the first manifold section to the first discharge port. Alternatively, each first inner end is in a straight line parallel to the outer circumference of the first shim up to a certain point from the first manifold section to the first discharge port, and then bends towards the center from that point onward, forming a bent line overall. However, the shape is not limited to these examples.

[0019] As described above, the first shim forms a wide groove-shaped first flow path, but due to the characteristic shape of the first inner ends on both sides of the first shim, the first flow path becomes tapered, narrowing towards the first discharge port. The taper amount of the first inner end is preferably 3.1 mm or more on each side.

[0020] Furthermore, it is preferable to slightly offset the tip of the first inner end on the first discharge port side rather than sharpening it. The amount of tip offset is preferably 0.1 mm or more and 1.0 mm or less in both the vertical and horizontal directions, and more preferably 0.1 mm or more and 0.46 mm or less.

[0021] Here, as you move away from the center of the first flow path (approaching the end), the discharge rate of the first coating liquid gradually decreases due to the decrease in hydraulic pressure, and the film thickness also decreases. This decrease itself can be adjusted by controlling the hydraulic pressure using the thickness of the first shim. However, the way the film thickness drops near both ends in the width direction (the slope of the film thickness when graphed in the width direction) could not be controlled. With the above configuration, the first inner end of the first shim, which is tapered and narrows towards the first discharge port and has a certain amount of tip relief, increases the amount of the first coating liquid that collects at the end of the first discharge port just before discharge in the first flow path. As a result, the decrease in discharge rate as you approach the end is suppressed, and the film thickness is made uniform over a wide area of ​​the entire coating width of the first coating liquid. As a result, winding misalignment defects in the electrode winding process are suppressed, and the area with insufficient film thickness is kept to a minimum, thereby suppressing a decrease in yield.

[0022] 2. Die Head (Two-Layer) In addition to the upper part, lower part, and first shim described above, the die head according to this disclosure may further include an intermediate part disposed between the upper part and the lower part, and a second shim disposed between the upper part and the intermediate part. In this case, the first shim is sandwiched between the intermediate part and the lower part. This die head can also be called a two-layer die head that can apply two types of coating liquids in layers to a strip-shaped substrate.

[0023] 2.1 Intermediate Parts As described above, intermediate parts are positioned between the upper and lower parts. Like the upper and lower parts, intermediate parts are made of a metal material such as Invar or stainless steel. Intermediate parts may be formed in a generally triangular prism shape, sandwiched between the upper and lower parts.

[0024] 2.2 Additional Configuration of the Upper Part The upper part has a second manifold section formed therein for storing the second coating liquid. The type of the second coating liquid is not particularly limited, but it is different from the first coating liquid. The second manifold section may be formed as a recess on the lower surface of the upper part. The second coating liquid is supplied to the second manifold section from an external second coating liquid supply means.

[0025] 2.3 Second Shim As described above, the second shim is positioned between the upper part and the intermediate part. The second shim is a plate-shaped member that surrounds the second manifold section in such a way that it blocks all but one direction, thereby forming a second flow channel through which the second coating liquid flows. This one direction is the same as the one direction that the first shim does not block. For example, if the lower surface of the upper part and the upper surface of the intermediate part are both horizontally elongated rectangles in plan view, the second shim will surround the second manifold section in such a way that it blocks all but one direction, i.e., three directions, thereby forming a wide groove-shaped second flow channel. The plan view shape of the second manifold section may be made to match the plan view shape of the portion of the second manifold section surrounded by the second shim.

[0026] On one side of the second flow path, a second discharge port opens for discharging the second coating liquid onto the strip-shaped substrate. In other words, the second coating liquid stored in the second manifold flows in the only direction not blocked by the second shim, and the second discharge port opens in this direction.

[0027] 2.4 Characteristics of the shape of the second shim The left and right second inner ends of the second shim may have the same shape as the first inner end. That is, both the left and right second inner ends of the second shim are straight or bent from the second manifold to the second discharge port. The distance between each second inner end is narrower on the second discharge port side than on the second manifold side. The taper amount of the second inner end is preferably 3.1 mm or more. The tip relief amount of the second inner end on the second discharge port side is preferably 0.1 mm or more and 1.0 mm or less in both the vertical and horizontal directions, and more preferably 0.1 mm or more and 0.46 mm or less. The shape of the outer circumference may also be the same as that of the first shim.

[0028] With this configuration, the film thickness is made uniform over a wide area of ​​the entire coating width of the first and second coating liquids. As a result, winding misalignment defects in the electrode winding process are suppressed, and the area with insufficient film thickness is kept to a minimum, thereby suppressing a decrease in yield.

[0029] 2.5 The first coating film and the second coating film formed by applying the first coating liquid and the second coating liquid may have different thicknesses.

[0030] The thickness of the first shim and the thickness of the second shim may be configured as follows: That is, the first liquid pressure when the first discharge port discharges the first coating liquid and the second liquid pressure when the second discharge port discharges the second coating liquid are both 80 kPa or less, and the difference between the first liquid pressure and the second liquid pressure is 20 kPa or less.

[0031] The viscosity of the first and second coating liquids at room temperature (e.g., 25°C) may be, for example, 2,000 to 8,000 mPa·s. The viscosity of the first and second coating liquids can be determined, for example, using a vibrating viscometer (e.g., VM-100A, manufactured by Sekonic Corporation). Furthermore, the viscosity of the first and second coating liquids when shear is applied, the so-called shear viscosity, is preferably 80 Pa·s or more when the shear rate is 0.01 / second, i.e., when simulating a static state.

[0032] The tanδ (ratio of storage shear modulus G' to loss shear modulus G'': G'' / G') of the first and second coating solutions at room temperature (e.g., 25°C) may be, for example, 0.5 to 1.1. The storage shear modulus G' and loss shear modulus G'' are determined using a viscoelasticity measuring device (e.g., Discovery Hybrid Rheometer HR2, manufactured by TA Instruments).

[0033] With this configuration, the film thickness is made uniform over a wide area of ​​the entire coating width of the first and second coating liquids. As a result, winding misalignment defects in the electrode winding process are further suppressed, and the area with insufficient film thickness is kept to a minimum, thereby suppressing a decrease in yield.

[0034] 3. Specific Examples of Die Heads Below, examples of die heads relating to this disclosure will be described with reference to the drawings. The components of the die head described below can be adapted to the components described above and can be modified based on the above description. Furthermore, the matters described below may be applied to the embodiments described above. Among the components of the die head described below, components that are not essential to the die head relating to this disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the actual shape and number of components.

[0035] 3.1 Single-Layer Die Head 10 Figure 1 is a schematic cross-sectional view illustrating the configuration of a die head 10 according to the first embodiment of the present disclosure. Figure 2 is a plan view illustrating the state in which the first shim 51 is placed on the lower part 30 of the die head 10. Figure 3 is a plan view showing only the first shim 51 of Figure 2. Figure 4 is an enlarged plan view of the first inner end 51R of the first shim 51 and its surrounding area.

[0036] As shown in Figure 1, the die head 10 comprises an upper part 20, a lower part 30, and a first shim 51 positioned between the upper part 20 and the lower part 30. This die head 10 is a horizontal single-layer die head capable of applying one type of coating liquid to a strip-shaped substrate B.

[0037] The upper component 20 is positioned above the die head 10 and constitutes approximately half of the die head 10. The upper component 20 is made of a metal material such as Invar or stainless steel. The upper component 20 is formed as a somewhat flattened rectangular parallelepiped, and its lower surface is substantially flat.

[0038] The lower part 30 is positioned below the die head and constitutes roughly the remaining half of the die head 10 after removing the upper part 20. The lower part 30 is also made of a metal material such as Invar material or stainless steel. The lower part 30 is also formed as a somewhat flattened rectangular parallelepiped overall. A first manifold section 32 for accumulating the first coating liquid is formed as a recess on the upper surface of the lower part 30. The first coating liquid is supplied to the first manifold section 32 from the outside through an inflow passage 31.

[0039] As shown in Figures 2 to 4, the first shim 51 is a thin plate-like member that surrounds the first manifold section 32 in such a way that it blocks three directions, thereby forming a wide groove-shaped first flow path 33 through which the first coating liquid flows. The first coating liquid stored in the first manifold section 32 flows through the only direction that is not blocked. Further along, a first discharge port 34 opens to discharge the first coating liquid onto a strip-shaped substrate being conveyed by a conveyor roller (not shown). An inlet 35 (not shown in Figure 1) is provided at one end (the side that leads to the outside) of the inflow passage 31 inside the lower component 30, and piping (not shown) for supplying the first coating liquid is connected to this inlet 35.

[0040] In a plan view, the outer periphery of the first shim 51, which covers both ends excluding the first discharge port 34 in three blocked directions and one unblocked direction, matches the outer contours of the upper part 20 and the lower part 30. The portion of the first shim 51 surrounding the first manifold portion 32 also matches the plan-view shape of the first manifold portion 32 which is a horizontally elongated rectangular shape with rounded corners.

[0041] Both the left and right first inner end portions 51L, 51R of the first shim 51 are linearly formed from the first manifold portion 32 to the first discharge port 34. The spacing between each of the first inner end portions 51L, 51R is narrower at the first discharge port 34 side than at the first manifold portion 32 side. The taper amount d1 of the first inner end portions 51L, 51R is set to be not less than 3.1 mm, and the tip relief amounts d2, d3 at the first discharge port 34 side are set to be not less than 0.1 mm and not more than 0.46 mm in both vertical and horizontal directions, respectively.

[0042] 3.2 Modified Example of First Shim for Single-Layer Die Head 10 Fig. 5 is a plan view illustrating a state where a first shim 51A having a different shape of first inner end portion is placed on the lower part 30. Fig. 6 is a plan view showing only the first shim 51A of Fig. 5.

[0043] As shown in Fig. 5 and Fig. 6, both the left and right first inner end portions 51AL, 51AR of the first shim 51A are formed in a polygonal line shape from the first manifold portion 32 to the first discharge port 34. Specifically, from the first manifold portion 32 to the first discharge port 34, the first half portion is linear parallel to the outer peripheral portion of the first shim 51A, and the portion beyond that is linear that is bent toward the center side, so that the entire end portion is formed in a polygonal line shape. Except for this, the shape of each part of the first shim 51A is the same as that of the first shim 51.

[0044] 3.3 Two-Layer Die Head Fig. 7 is a cross-sectional view illustrating a schematic configuration of a die head 10B according to a second embodiment of the present disclosure.

[0045] As shown in Fig. 7, the die head 10B includes an upper component 20B, a lower component 30B, an intermediate component 40B disposed between the upper component 20B and the lower component 30B, a first shim 51B disposed between the intermediate component 40B and the lower component 30B, and a second shim 52B disposed between the upper component 20B and the intermediate component 40B. The die head 10B is a horizontal two-layer die head that can apply two types of coating liquids in an overlapping manner onto a belt-shaped base material B.

[0046] The upper component 20B is disposed on the upper side of the die head 10B and is made of a metal material such as invar or stainless steel. On the lower surface of the upper component 20B, a second manifold portion 22B for storing the second coating liquid is formed as a recess. The second coating liquid is supplied to the second manifold portion 22B from the outside through an inflow path 21B.

[0047] As described above, the intermediate component 40B is disposed between the upper component 20B and the lower component 30B. The intermediate component is also made of a metal material such as invar or stainless steel. The intermediate component 40B is formed into a generally triangular prism shape sandwiched between the upper component 20B and the lower component 30B.

[0048] The lower component 30B is disposed on the lower side of the die head 10B, and is similarly made of a metal material such as invar or stainless steel. On the upper surface of the lower component 30B, a first manifold portion 32B for storing the first coating liquid is formed as a recess. The first coating liquid is supplied to the first manifold portion 32B from the outside through an inflow path 31B.

[0049] The first shim 51B is a thin plate-shaped member that forms a wide groove-shaped first flow path 33B through which the first coating liquid flows by surrounding the first manifold portion 32B so as to block three sides of the first manifold portion 32B. The first coating liquid stored in the first manifold portion 32B flows toward the only unblocked direction. On the tip side of this direction, a first discharge port 34B that discharges the first coating liquid onto the belt-shaped base material B conveyed by a conveyance roller (not shown) is opened.

[0050] The second shim 52B is a thin plate-shaped member that forms a second flow path 23B through which the second coating liquid flows by surrounding the second manifold portion 22B so as to block all directions except one direction, same as the first shim 51B.

[0051] The plan view shapes of the first shim 51B and the second shim 52B are identical, and may, for example, be the same as the plan view shape of the first shim 51 or the first shim 51A described above. However, the thickness of the first shim 51B and the thickness of the second shim 52B are different and are defined as follows: That is, the first liquid pressure when the first discharge port 34B discharges the first coating liquid and the second liquid pressure when the second discharge port 24B discharges the second coating liquid are both 80 kPa or less, and the difference between the first liquid pressure and the second liquid pressure is within 20 kPa.

[0052] 4. The following technologies are disclosed by the above descriptions of embodiments. (Technology 1) A die head comprising: an upper part; a lower part having a first manifold section for storing a first coating liquid; and a plate-shaped first shim disposed between the upper part and the lower part, surrounding the first manifold section so as to block all but one direction, thereby forming a first flow path through which the first coating liquid flows; a first discharge port for discharging the first coating liquid onto a strip-shaped substrate is opened on the one-direction side of the first flow path; the left and right first inner ends of the first shim are both straight or bent from the first manifold section to the first discharge port; the distance between each of the first inner ends is narrower on the first discharge port side than on the first manifold section side; the taper amount of the first inner ends is 3.1 mm or more; and the tip relief amount of the first inner ends on the first discharge port side is 0.1 mm or more and 1.0 mm or less in both the vertical and horizontal directions. (Technology 2) The die head according to Technology 1, wherein the tip relief amount is 0.1 mm or more and 0.46 mm or less in both the vertical and horizontal directions. (Technology 3) The die head according to Technology 1 or 2, further comprising an intermediate part disposed between the upper part and the lower part, and a second shim disposed between the upper part and the intermediate part, wherein a second manifold section for accumulating a second coating liquid is formed in the upper part, the second shim forms a second flow path through which the second coating liquid flows by surrounding the second manifold section so as to block all directions except the one direction, a second discharge port for discharging the second coating liquid onto the substrate is opened on the one-direction side of the second flow path, the left and right second inner ends of the second shim are the same shape as the first inner ends, and the first shim is sandwiched between the intermediate part and the lower part. (Technical 4) The die head according to Technical 3, wherein the first coating film formed on the substrate by the first coating liquid and the second coating film formed on the substrate by the second coating liquid have different thicknesses. (Technical 5) The die head according to Technical 4, wherein the thickness of the first shim and the thickness of the second shim are configured such that the first liquid pressure when the first discharge port discharges the first coating liquid and the second liquid pressure when the second discharge port discharges the second coating liquid are both 80 kPa or less, and the difference between the first liquid pressure and the second liquid pressure is 20 kPa or less.(Technical 6) The die head according to any one of Technical 1 to 5, wherein the substrate is a negative electrode current collector of a lithium-ion secondary battery, and the first coating liquid is a negative electrode mixture slurry of the lithium-ion secondary battery. (Technical 7) The die head according to any one of Technical 1 to 6, wherein the width of the substrate is 60 to 140 cm.

[0053] This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. Furthermore, various disclosures can be formed by appropriately combining the multiple components disclosed in the embodiments described above. For example, some components may be removed from all the components shown in the embodiments. The drawings schematically show each component for ease of understanding, and the number of each component shown may differ from the actual number due to the convenience of drawing creation. In addition, each component shown in the embodiments described above is an example and is not particularly limiting, and various modifications are possible without substantially departing from the effects of this disclosure.

[0054] This disclosure is applicable to die heads.

[0055] 10 Die head 10B Die head 20 Upper part 20B Upper part 21B Inlet passage 22B Second manifold section 23B Second flow path 24B Second discharge port 30 Lower part 30B Lower part 31 Inlet passage 31B Inlet passage 32 First manifold section 32B First manifold section 33 First flow path 33B First flow path 34 First discharge port 34B First discharge port 35 Inlet 40B Intermediate part 51 First shim 51L First inner end (left side) 51R First inner end (right side) 51A First shim 51AL First inner end (left side) 51AR First inner end (right side) 51B First shim 52B Second shim

Claims

1. A die head comprising: an upper part; a lower part having a first manifold section for storing a first coating liquid; and a plate-shaped first shim positioned between the upper part and the lower part, surrounding the first manifold section so as to block all but one direction, thereby forming a first flow path through which the first coating liquid flows; a first discharge port for discharging the first coating liquid onto a strip-shaped substrate is opened on the one-direction side of the first flow path; the left and right first inner ends of the first shim are both straight or bent from the first manifold section to the first discharge port; the distance between each of the first inner ends is narrower on the first discharge port side than on the first manifold section side; the taper amount of the first inner ends is 3.1 mm or more; and the tip relief amount of the first inner ends on the first discharge port side is 0.1 mm or more and 1.0 mm or less in both the vertical and horizontal directions.

2. The die head according to claim 1, wherein the tip relief amount is 0.1 mm or more and 0.46 mm or less in both the vertical and horizontal directions.

3. The die head according to claim 1, further comprising an intermediate part disposed between the upper part and the lower part, and a second shim disposed between the upper part and the intermediate part, wherein the upper part has a second manifold section for storing the second coating liquid, the second shim surrounds the second manifold section so as to block all directions except the one direction, thereby forming a second flow path through which the second coating liquid flows, a second discharge port for discharging the second coating liquid onto the substrate opens on the one-direction side of the second flow path, the left and right second inner ends of the second shim are the same shape as the first inner ends, and the first shim is sandwiched between the intermediate part and the lower part.

4. The die head according to claim 3, wherein the first coating film formed on the substrate by the first coating liquid and the second coating film formed on the substrate by the second coating liquid have different thicknesses.

5. The die head according to claim 4, wherein the thickness of the first shim and the thickness of the second shim are configured such that the first liquid pressure when the first discharge port discharges the first coating liquid and the second liquid pressure when the second discharge port discharges the second coating liquid are both 80 kPa or less, and the difference between the first liquid pressure and the second liquid pressure is 20 kPa or less.

6. The die head according to any one of claims 1 to 5, wherein the substrate is a negative electrode current collector of a lithium-ion secondary battery, and the first coating liquid is a negative electrode mixture slurry of the lithium-ion secondary battery.

7. The die head according to any one of claims 1 to 5, wherein the width of the substrate is 60 to 140 cm.

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