Die head

Abstract

To provide a die head that improves product yield. [Solution] A die head 10 for applying a coating liquid to a substrate, the die head 10 has a manifold 40 that extends substantially parallel to the width direction of the substrate and stores the coating liquid, a supply passage 50 that supplies the coating liquid to the manifold 40 from the outside, a discharge port 61 that discharges the coating liquid supplied to the manifold 40 toward the substrate, and a discharge passage 60 that connects the manifold 40 and the discharge port 61, wherein the inflow direction D1 in which the coating liquid flows toward the manifold 40 through the supply passage 50 is set to an angle θ in the range of 45° to 135° with respect to the discharge direction D2 in which the coating liquid flows toward the discharge port 61 through the discharge passage 60 from the manifold 40.

Description

Technical Field

[0001] The present disclosure relates to a die head, and particularly to a die head for applying a coating liquid to a substrate.

Background Art

[0002] A die head that discharges a coating liquid stored in a manifold to apply the coating liquid to a substrate is known. Such a die head may be configured to spread the coating liquid in the width direction in the manifold and discharge it. And, as a technique for equalizing the flow rate distribution in the width direction of the discharged coating liquid, Patent Document 1 can be cited.

[0003] Patent Document 1 discloses a die head including a pair of die plates each having opposing planes parallel to each other, a flow path formed between the pair of die plates, and an internal block provided in the flow path, and the supplied coating liquid is discharged through the flow path. The die plates of this die head have at least two receiving surfaces, and the internal block is attached to the die plate in a state of abutting against the receiving surface, and the receiving surface is inclined with respect to the opposing plane in a side view.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the die head described in Patent Document 1 requires an internal block, which increases the number of parts and makes it larger and heavier. Furthermore, the die head described in Patent Document 1 not only has an internal block in the middle of the flow path, but also has multiple manifolds in the flow path, resulting in a complex shape. This increases the manufacturing cost of the die head and the maintenance man-hours such as cleaning after coating. For these reasons, the technology described in Patent Document 1 has the problem of reducing product yield.

[0006] This disclosure was made to solve these problems and aims to provide a die head that improves product yield. [Means for solving the problem]

[0007] A die head according to one embodiment is a die head for applying a coating liquid to a substrate, and comprises a manifold extending substantially parallel to the width direction of the substrate for storing the coating liquid, a supply passage for supplying the coating liquid to the manifold from the outside, a discharge port for discharging the coating liquid supplied to the manifold toward the substrate, and a discharge passage connecting the manifold and the discharge port, wherein the inflow direction in which the coating liquid flows toward the manifold through the supply passage is set to an angle θ in the range of 45° to 135° with respect to the discharge direction in which the coating liquid flows from the manifold toward the discharge port through the discharge passage. [Effects of the Invention]

[0008] This disclosure makes it possible to provide a die head that improves product yield. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows the configuration of the die head according to Embodiment 1. [Figure 2] This diagram shows the configuration of the die head in the comparative example. [Figure 3] This is a CAE analysis result showing the flow of the coating solution during application using a die head. [Modes for carrying out the invention]

[0010] Embodiment 1 The following describes specific embodiments applying this disclosure with reference to the drawings. However, this disclosure is not limited to the following embodiments. Also, for clarity, the following description and drawings have been simplified as appropriate.

[0011] Note that the right-handed xyz Cartesian coordinate system shown in Figures 1-3 is for convenience in explaining the positional relationships of the constituent elements. Typically, the positive z-axis is vertically upward, and the xy-plane is horizontal.

[0012] Figure 1 shows the configuration of a die head according to Embodiment 1. The die head 10 according to this embodiment is installed in a coating apparatus used, for example, in the manufacture of electrodes for secondary batteries such as all-solid-state batteries. The electrodes of secondary batteries are sheet-shaped electrode materials obtained by coating electrode slurry onto electrode foil and drying it. In this embodiment, electrode foil such as aluminum is used as the base material, and electrode slurry is used as the coating liquid. However, the base material and coating liquid are not limited to these.

[0013] Figure 1(a) shows a cross-sectional view of the die head 10. Figure 1(b) shows a plan view of the second head section 30. Figure 1(c) is a cross-sectional view taken along line I-I in Figure 1(b).

[0014] The die head 10 according to this embodiment applies a coating liquid to a substrate. As shown in Figure 1(a), the die head 10 has a first head portion 20 and a second head portion 30 as a pair of dies facing each other. The first head portion 20 is formed in a substantially rectangular parallelepiped shape that is long in the y-axis direction. The first head portion 20 has an opposing plane 21 that is positioned to face the second head portion 30. The first head portion 20 has a lip 22 that extends in the positive x-axis direction. The lip 22 extends in the y-axis direction. The lip 22 constitutes a part of the opposing plane 21.

[0015] The second head portion 30 is formed in a substantially rectangular parallelepiped shape that is elongated in the y-axis direction. The second head portion 30 has opposing planes 31 that are positioned to face the first head portion 20. The second head portion 30 has a lip 32 that extends toward the positive x-axis. The lip 32 constitutes a part of the opposing planes 31.

[0016] The manifold 40 extends in the y-axis direction substantially parallel to the width direction of the substrate and stores the coating liquid. The manifold 40 is located inside a pair of dies. In this embodiment, the manifold 40 is located in the second head portion 30. The manifold 40 is positioned substantially in the center of the opposing plane 31. The manifold 40 is formed in a groove shape that is recessed toward the negative z-axis side from the opposing plane 31 and extends in the y-axis direction.

[0017] The manifold 40 is a larger space in volume than the supply passage 50 and discharge passage 60, which will be described later. By temporarily storing the coating liquid in the manifold 40 and then sending it to the discharge port 61, which will be described later, the discharge stability of the coating liquid can be improved.

[0018] The supply passage 50 is a flow path that supplies coating liquid from outside the die head 10 to the manifold 40. The supply passage 50 is located inside the pair of dies. In this embodiment, the supply passage 50 is located in the first head section 20. The supply passage 50 extends from the upper surface 23 opposite to the opposing plane 21 of the first head section 20 to the opposing plane 21, so as to penetrate the first head section 20.

[0019] The supply channel 50 receives coating liquid from a tank (not shown) that stores the coating liquid via a pump (not shown). The supply channel 50 is connected to the manifold 40. From the viewpoint of equalizing the flow rate distribution of the coating liquid in the y-axis direction, it is preferable that the supply channel 50 is connected to the center of the manifold 40 in the y-axis direction.

[0020] The inlet 51 is an opening for allowing the coating liquid supplied from the supply path 50 to flow into the manifold 40. The inlet 51 is a portion that opens to the opposing plane 21 of the supply path 50. From the viewpoint of equalizing the flow rate distribution of the coating liquid in the y-axis direction, the inlet 51 is preferably arranged at the center of the manifold 40 in the y-axis direction and on the negative x-axis side of the manifold 40.

[0021] The discharge path 60 is provided inside the pair of dies. The discharge path 60 is a flow path connecting the manifold 40 and the discharge port 61. The discharge path 60 is formed between the opposing planes 21 and 31 of the lips 22 and 32 by sandwiching a plate-shaped shim 70 between the opposing planes 21 and 31. The shim 70 is a member for forming the discharge path 60 between the opposing planes 21 and 31.

[0022] The discharge port 61 is an opening for discharging the coating liquid in the manifold 40 toward the substrate. The discharge port 61 is a portion that opens to the lip surface 11 of the discharge path 60. The lip surface 11 is a surface that faces the substrate conveyed by the pair of dies. The discharge port 61 is formed in a slit shape extending in the y-axis direction.

[0023] The die head 10 is arranged such that the discharge port 61 faces the outer peripheral surface of the backup roll provided in the coating apparatus with a predetermined interval. The backup roll conveys the substrate in its longitudinal direction by rotating. Then, the substrate is continuously conveyed to a position where the backup roll and the discharge port 61 face each other along the outer peripheral surface of the rotating backup roll.

[0024] The coating liquid supplied from the supply path 50 flows into the manifold 40 through the inlet 51. The coating liquid flowing into the manifold 40 is temporarily stored in the manifold 40 and then reaches the discharge port 61 via the discharge path 60 and is discharged from the discharge port 61. Thereby, the coating liquid is applied to the substrate in a strip shape.

[0025] The coating liquid is spread in both directions along the y-axis by the manifold 40, passes through the discharge passage 60, and is discharged from the discharge port 61. Therefore, the coating width in the y-axis direction of the coating liquid is approximately the same as the dimension of the discharge port 61 in the y-axis direction. Also, the coating thickness in the z-axis direction of the coating liquid is approximately the same as the dimension of the discharge port 61 in the z-axis direction.

[0026] Furthermore, the inflow direction D1 (direction of the white arrow shown in Figure 1), through which the coating liquid flows towards the manifold 40 via the supply passage 50, is set to an angle θ in the range of 45° to 135° with respect to the discharge direction D2 (direction of the black arrow shown in Figure 1), through which the coating liquid flows from the manifold 40 towards the discharge port 61 via the discharge passage 60. By setting the angle θ in the range of 45° to 135°, the die head 10 can suppress backflow and vortices of the coating liquid within the manifold 40, which would otherwise worsen the flow of the coating liquid.

[0027] When deterioration of the coating liquid flow within the manifold 40 is suppressed, a flow of coating liquid that diffuses uniformly in both directions along the y-axis is formed within the manifold 40. In this way, the die head 10 according to this embodiment can equalize the flow rate distribution of the coating liquid in the y-axis direction, so that the coating liquid is discharged from the discharge port 61 in a state where it has diffused uniformly in both directions along the y-axis, making it less likely for coating defects such as streaks or transparency to occur in the coating liquid applied to the substrate from the beginning of coating. Therefore, the die head 10 according to this embodiment can improve the discharge stability of the coating liquid and suppress a decrease in product yield with a simple structure that does not easily lead to increased size, weight, or complex shape.

[0028] On the other hand, if the angle θ is outside the range of 45° to 135°, it may be difficult to form the supply passage 50 inside the die head 10. From the viewpoint of easily forming the supply passage 50, it is preferable that the angle θ is 90°. In this embodiment, the inflow direction D1 is parallel to the z-axis direction and the discharge direction D2 is parallel to the x-axis direction, so the angle θ is 90°.

[0029] The manifold 40 is designed to push the coating liquid stored in the manifold 40 to the discharge passage 60 when the amount of coating liquid stored in the manifold 40 exceeds the capacity of the manifold 40. Therefore, it is preferable that the manifold 40 be formed in a shape that allows the stored coating liquid to flow easily to the discharge passage 60.

[0030] Here, as shown in Figure 1(b), the manifold 40 has a bottom surface 41 extending substantially parallel to the xy plane, inner surfaces 42 and 43 extending in the positive z-axis direction from a pair of edges of the bottom surface 41 that are opposite to each other in the x-axis direction, and R-shaped sections 44 and 45 connecting the inner surfaces 42 and 43.

[0031] The inner surfaces 42 and 43 face each other in the x-axis direction. Inner surface 42 is located on the positive x-axis side (upstream side of the discharge direction D2). Inner surface 43 is located on the negative x-axis side (downstream side of the discharge direction D2). The width of inner surface 43 in the y-axis direction is smaller than the width of inner surface 42 in the y-axis direction.

[0032] The R sections 44 and 45 are located at both ends of the manifold 40 in the y-axis direction. R section 44 is located on the positive y-axis side. R section 45 is located on the negative y-axis side. R sections 44 and 45 have a gently curved shape. Because the manifold 40 has R sections 44 and 45 formed in a gently curved shape at each corner on the negative x-axis side, the coating liquid that flows into the manifold 40 through the inlet 51 flows along the shape of R sections 44 and 45 as it flows through them, thus allowing the direction of flow to be gently changed. Therefore, backflow and vortices of the coating liquid within the manifold 40, which would otherwise worsen the flow of the coating liquid, can be suppressed.

[0033] From the viewpoint of suppressing deterioration of the coating liquid flow within the manifold 40, it is preferable that the radius of curvature of the R sections 44 and 45 be as large as possible. The radius of curvature may be, for example, 100 mm to 150 mm. In this embodiment, the radius of curvature is 100 mm. This is sufficient to suppress deterioration of the coating liquid flow within the manifold 40.

[0034] Furthermore, as shown in Figure 1(c), the cross-sectional shape of the manifold 40, when viewed from the y-axis direction, is formed to be, for example, a roughly arc shape. The cross-section of such a manifold 40 is formed so that the cross-sectional area gradually increases from a pair of edges of the bottom surface 41 toward both x-axis directions. As a result, when the coating liquid stored in the manifold 40 is pushed out to the discharge passage 60, the coating liquid flows easily from the manifold 40 to the discharge passage 60.

[0035] Furthermore, it is preferable that the manifold 40 has a capacity less than the inflow rate of the coating liquid per unit time. By having a manifold 40 with a capacity less than the inflow rate of the coating liquid per unit time, the die head 10 can improve the discharge stability of the coating liquid and suppress a decrease in product yield. The capacity of the manifold 40 may be, for example, 20 mL to 100 mL. In this embodiment, the capacity of the manifold 40 is 20 mL.

[0036] Here, the inflow rate of coating solution per unit time (mL) can be calculated using the following formula (1), where A is the coating width of the coating solution (mm), t is the coating thickness of the coating solution (μm), and v is the transport speed of the substrate (m / min). A × t × v × 10 -3 ...Equation (1)

[0037] Furthermore, it is preferable that the manifold 40 has a depth d1 such that its capacity is less than the inflow rate of coating liquid per unit time. From the viewpoint of promoting the diffusion of the coating liquid in both y-axis directions within the manifold 40, it is preferable that the depth d1 of the manifold 40 be as small as possible. The depth d1 of the manifold 40 may be, for example, 2 mm to 10 mm. In this embodiment, the capacity of the manifold 40 is 2 mm. The depth d1 of the manifold 40 is the recess depth of the second head portion 30.

[0038] Next, Figure 2 shows the configuration of the die head according to the comparative example. As shown in Figure 2, the die head 10a according to the comparative example has a first head section 20, a second head section 30, a manifold 40a, a supply passage 50a, an inlet 51a, a discharge passage 60, and a discharge port 61. Note that in Figure 2, the same reference numerals are used for components corresponding to those in Figure 1. Below, the configuration of the die head 10a according to the comparative example will be explained, focusing on the differences from the die head 10.

[0039] Figure 2(a) shows a cross-sectional view of the die head 10a. Figure 2(b) shows a plan view of the second head section 30. Figure 2(c) is a cross-sectional view taken along line II-II in Figure 2(b).

[0040] As shown in Figure 2(a), unlike the supply passage 50 of the die head 10, the supply passage 50a of the die head 10a is provided in the second head section 30. The supply passage 50a extends from the x-axis negative end face 33 of the second head section 30 to the inner surface 43 of the manifold 40a. The supply passage 50a is connected to the center of the manifold 40a in the y-axis direction. The supply passage 50a has an inlet 51a that opens onto the inner surface 43.

[0041] Furthermore, the die head 10a is configured such that the inflow direction D1 (direction of the white arrow in Figure 2), through which the coating liquid flows from the manifold 40a to the manifold 40a, is set at an angle θ of 180° with respect to the discharge direction D2 (direction of the black arrow in Figure 2), through which the coating liquid flows from the manifold 40a to the discharge port 61 via the discharge path 60. In other words, the angle θ is set outside the range of 45° to 135°. If the angle θ is too large in this way, there is a risk that backflow or vortices will occur in the manifold 40a, worsening the flow of the coating liquid. If the flow of the coating liquid in the manifold 40a worsens, it becomes difficult for the coating liquid to diffuse uniformly in both directions along the y-axis.

[0042] Next, as shown in Figure 2(b), the manifold 40a of the die head 10a has R sections 44a and 45a at each corner on the negative x-axis side, with a radius of curvature smaller than that of R sections 44 and 45. As a result, when the coating liquid flows into the manifold 40a via the inlet 51a, it flows along the shape of R sections 44a and 45a, so the direction of flow can change abruptly at an angle close to right. Therefore, there is a risk that backflow or vortices of the coating liquid will occur within the manifold 40a, worsening the flow of the coating liquid. If the flow of the coating liquid worsens within the manifold 40a, it becomes difficult for the coating liquid to diffuse uniformly in both directions along the y-axis.

[0043] Next, as shown in Figure 2(c), the manifold 40a of the die head 10a has a depth d2 that is greater than the depth d1 of the manifold 40. This may prevent sufficient diffusion of the coating liquid in both directions along the y-axis.

[0044] As explained using Figure 2, if the coating liquid does not diffuse uniformly in both directions along the y-axis, the flow rate distribution of the coating liquid in the y-axis direction becomes uneven, reducing the discharge stability of the coating liquid. As a result, compared to die head 10, die head 10a is prone to coating defects such as streaks and transparency in the coating liquid applied to the substrate from the beginning of the coating process, leading to a problem of reduced product yield.

[0045] Next, the flow of the coating solution during application using two die heads with different angles θ was analyzed using CAE (Computer-Aided Engineering). The analysis results are shown in Figure 3. Figure 3 shows the CAE analysis results illustrating the flow of the coating solution during application using a die head. The left side of Figure 3 shows the analysis results illustrating the flow of the coating solution within the die head when applying the coating solution using a die head with an angle θ of 90°. The right side of Figure 3 shows the analysis results illustrating the flow of the coating solution within the die head when applying the coating solution using a die head with an angle θ of 180°.

[0046] As can be seen from the analysis results of the coating fluid velocity distribution shown in Figure 3, in the case of a die head with an angle θ of 180°, the straight-line propagation of the coating fluid along the x-axis becomes high within the die head due to the angle θ being too large. Therefore, the coating fluid does not easily diffuse in both directions along the y-axis. Furthermore, as can be seen from the analysis results of the coating fluid streamlines shown in Figure 3, in the case of a die head with an angle θ of 180°, backflow of the coating fluid and vortices caused by this backflow occur within the die head, resulting in an unstable flow of the coating fluid from the discharge passage 60 to the discharge port 61.

[0047] On the other hand, as can be seen from the analysis results of the coating fluid velocity distribution shown in Figure 3, in the case of a die head with an angle θ of 90°, the straight-line propagation of the coating fluid along the x-axis is suppressed within the die head due to the angle of the inflow direction D1 relative to the discharge direction D2. Therefore, the coating fluid tends to diffuse in both directions along the y-axis. Furthermore, as can be seen from the analysis results of the coating fluid streamlines shown in Figure 3, in the case of a die head with an angle θ of 90°, no backflow of the coating fluid or generation of vortices due to such backflow is observed from the inlet 51 to the discharge port 61 within the die head, and a flow of coating fluid that diffuses uniformly in both directions along the y-axis is formed within the manifold. And, because the flow of the coating fluid from the discharge passage 60 to the discharge port 61 is stable in a die head with an angle θ of 90°, it can be seen that the discharge stability is higher compared to a die head with an angle θ of 180°.

[0048] Based on the above, this disclosure provides a die head that improves product yield.

[0049] This disclosure is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, the angle θ is not limited to 90° as long as it is in the range of 45° to 135°. Although not shown in the figures, CAE analysis was performed on the flow of the coating solution during coating using a die head with an angle θ of 45° and a die head with an angle θ of 135°. The results were equivalent to those obtained for the die head with an angle θ of 90°. [Explanation of symbols]

[0050] 10, 10a Die head 11 Lip surface 20 First head section 21 Opposing plane 22 Lip 23 Top surface 30 Second head portion 31 Opposing plane 32 Lip 33 End face 40, 40a Manifold 41 Bottom surface 42, 43 Inner surface 44, 44a, 45, 45a R section 50, 50a Supply channel 51, 51a Inlet 60 Discharge path 61 Discharge port 70 Sims D1 Inflow direction D2 Discharge direction

Claims

[Claim 1] A die head for applying a coating liquid to a substrate, A manifold extending substantially parallel to the width direction of the substrate and storing the coating liquid, A supply passage for supplying the coating liquid to the manifold from the outside, A discharge port for discharging the coating liquid supplied to the manifold toward the substrate, It has a discharge passage connecting the manifold and the discharge port, A die head in which the inflow direction of the coating liquid flowing from the supply passage toward the manifold is set to an angle θ in the range of 45° to 135° with respect to the discharge direction of the coating liquid flowing from the manifold toward the discharge port through the discharge passage.

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