Slot die coater

Abstract

The present invention provides a slot die coater that improves distortion of a die block caused by internal pressure. The slot die coater of the present invention includes an upper plate and a lower plate that are combined with each other to form an outlet, and a shim that is interposed between the lower plate and the upper plate to form a slot that communicates with the outlet, the upper plate having a groove that is parallel to the shim and extends into the upper plate above the slot, and further including a taper block and a pressing bolt that are inserted into the groove to press the shim.

Description

[Technical field]

[0001] The present invention relates to a slot die coater, and more particularly to a slot die coater in which distortion of a die block due to internal pressure is improved.

[0002] This application claims priority to Korean Patent Application No. 10-2022-0094861 filed on July 29, 2022 and Korean Patent Application No. 10-2023-0062678 filed on May 15, 2023, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] The recent technological development and increasing demand for mobile devices have been remarkable, and 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 applying a positive electrode active material slurry and a negative electrode active material slurry to current collectors made of aluminum foil and copper foil, respectively, and drying them. Such secondary batteries generally 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. In addition, carbon-based materials are mainly used as negative electrode active materials, and recently, due to the increasing need for high-energy lithium secondary batteries, it has been considered to use them in combination with silicon-based materials and silicon oxide-based materials that have an effective capacity 10 times or more larger than that of carbon-based materials. 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.

[0004] FIG. 1 is a perspective view showing a conventional slot die coater, and FIG. 2 is an exploded perspective view of the conventional slot die coater.

[0005] 1 and 2, in a method for manufacturing an electrode using a slot die coater 1, an active material slurry discharged from the slot die coater 1 is applied onto a current collector (not shown) conveyed by a coating roll (not shown). The active material slurry discharged from the slot die coater 1 is applied widely onto one side of the current collector to form an active material layer.

[0006] The slot die coater 1 includes two die blocks 10, 20, with a slot 30 formed between the two die blocks 10, 20. The two die blocks 10, 20 are fastened together by a connecting bolt 70. An active material layer can be formed by discharging an active material slurry through a discharge port 40 communicating with the slot 30. The slot die coater 1 has the advantage of being capable of coating at high speeds compared to bar coating or comma coating, and is therefore frequently used from the viewpoint of high productivity.

[0007] The coating width of the active material layer coated on the current collector is determined by the width W of the slot 30. If a change in the coating width is required, various coating widths can be achieved by changing the internal space of the manifold 50 and the shim 60 that determines the width W of the slot 30.

[0008] The slot die coater 1 shown as an example in Figure 1 is a vertical die type in which active material slurry is discharged in the direction opposite to gravity. When coating is performed using the slot die coater 1 configured vertically, the die blocks 10, 20 may spread apart due to the internal pressure of the die blocks 10, 20. When using a shim 60 between the two die blocks 10, 20 to create an uncoated portion (a portion not coated on the current collector, a plain portion), if the two die blocks 10, 20 spread apart and the active material slurry flows in, the active material slurry may intermittently adhere to the uncoated portion, causing a problem of surface defects.

[0009] Fig. 3 is a cross-sectional view showing the initial bonding state of a conventional slot die coater, and corresponds to the cross-section taken along the line II-II' in Fig. 1. Fig. 4 is a cross-sectional view showing distortion due to internal pressure of the die in a conventional slot die coater. Fig. 5 is a diagram showing a problem in a conventional slot die coater in which slurry gets inside the die, causing surface defects in the uncoated parts of the current collector.

[0010] In Fig. 3, the two die blocks 10, 20 are fastened together by a connecting bolt 70. When the internal pressure of the die blocks 10, 20 increases, a torque T due to the internal pressure is generated with the connecting bolt 70 as the base point (reference point) as shown in Fig. 4. As a result, the farthest parts receive the greatest force, and the die lips 10a, 20a at the tips of the die blocks 10, 20 widen. This causes the active material slurry to seep into the parts of the shim 60 that should block the active material slurry and prevent it from being discharged.

[0011] 5, the active material slurry 75 penetrates into the inside of the die blocks 10 and 20 where it should not be present, causing surface defects 90 in the uncoated portions 80a of the current collector 80. Only when there are no surface defects 90 can slitting defects be generated when electrodes are formed on the active material layers 80b by slitting along the uncoated portions 80a formed in the MD direction, and even if there is a case, the surface defects 90 remaining in the uncoated portions 80a do not cause disconnection of the electrodes after the secondary battery is manufactured. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been devised in view of the above-mentioned circumstances, and an object of the present invention is to prevent the active material slurry from being discharged into the uncoated portion due to an increase in the internal pressure of the die.

[0013] Therefore, the problem to be solved by the present invention is to provide a slot die coater in which distortion of the die block due to internal pressure is improved.

[0014] 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]

[0015] The slot die coater of the present invention for solving the above-mentioned problems includes an upper plate and a lower plate which are combined with each other to form an outlet, and a shim which is interposed between the lower plate and the upper plate to form a slot communicating with the outlet, the upper plate having a groove which is parallel to the shim and extends into the upper plate above the slot, and further including a taper block and a pressure bolt which are inserted into the groove to press the shim.

[0016] The groove may have a height that gradually decreases toward the inside of the groove, with the inclination of the tapered block being matched thereto.

[0017] The pressure bolt may pass through the taper block from the front side of the groove and be fastened to the upper plate.

[0018] The groove is indented from the front surface to the rear surface of the upper plate, and the pressure bolt can be fastened to the taper block at the front surface of the upper plate.

[0019] The taper block is fastened to the pressure bolt and moves back and forth in a direction parallel to the discharge direction of the discharge port, and generates a force due to the height difference between the groove and the taper block, thereby pressing the shim.

[0020] The shim includes a plurality of extension portions that are connected vertically to a base portion to include a plurality of openings and extend toward the outlet side, the horizontal length of the taper block is not greater than the horizontal length of the extension portions, and the taper block can be inserted into the groove at a position corresponding to the extension portions.

[0021] The taper block may be provided at a position corresponding to the plurality of extension portions excluding the extension portions at the ends (sides).

[0022] The slot die coater may further include a manifold on the lower plate, and the length of the taper block may be shorter than the length of a land that is a region from a front end of the manifold to the discharge port.

[0023] According to one aspect of the present invention, the groove is formed on the ejection port side.

[0024] A bolt groove into which the pressure bolt is fastened may be formed at a position aligned with the groove.

[0025] A hole may be formed in the tapered block in registration with the bolt slot to allow the pressure bolt to pass therethrough.

[0026] According to another aspect of the present invention, the pressing bolt penetrates the upper plate from a rear surface of the upper plate and is fastened to the taper block.

[0027] The slot die coater includes a long hole in the width direction on the rear surface of the upper plate so that the pressing bolt can be inserted.

[0028] The pressing bolt and taper block may be provided in a plurality of numbers along the width direction.

[0029] A thread may be formed in the taper block to which the pressure bolt can be fastened.

[0030] The long hole may be formed from the rear surface of the upper plate toward the front surface, and the groove may be formed from the front surface of the upper plate toward the rear surface, with the long hole being formed at a position aligned with the groove.

[0031] A manifold may be provided on the lower plate for containing a coating fluid, the manifold being in communication with the slot.

[0032] The slot die coater applies the coating liquid by spitting it onto the substrate through the discharge port, and the shim may have a plurality of openings in which an area is intermittently cut out at intervals to determine the coating width of the coating layer applied onto the substrate.

[0033] The taper block and pressure bolt can press the shim without affecting the opening to prevent the upper and lower plates from spreading apart. Effect of the Invention

[0034] According to the present invention, the structure of the upper plate in the slot die coater is modified to further include a taper block and a pressure bolt, which can prevent the active material slurry from being discharged to the uncoated portion due to an increase in the internal pressure of the slot die.

[0035] This prevents the active material slurry from being discharged onto the uncoated areas, improving surface defects during electrode formation. In particular, when forming an active material layer in a stripe pattern, the active material layer can be stably formed without causing pattern defects in the uncoated areas.

[0036] By using such a slot die coater of the present invention, a coating layer, particularly an electrode active material layer, can be formed uniformly to a desired thickness and shape.

[0037] 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]

[0038] [Figure 1] FIG. 1 is a perspective view showing a conventional slot die coater. [Diagram 2] FIG. 1 is an exploded perspective view of a conventional slot die coater. [Diagram 3] FIG. 1 is a cross-sectional view showing an initial assembly state of a conventional slot die coater. [Figure 4] FIG. 1 is a cross-sectional view showing distortion due to internal pressure of a die in a conventional slot die coater. [Diagram 5] FIG. 1 is a diagram showing a problem in which slurry gets inside the die in a conventional slot die coater, causing surface defects in uncoated areas of a current collector. [Figure 6] FIG. 1 is a perspective view showing a slot die coater according to one embodiment of the present invention. [Figure 7] 7 is a cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. 6. [Figure 8] FIG. 8 is a diagram of a modified example of the slot die coater shown in FIG. 7. [Figure 9] 7 is another cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. 6. [Figure 10] FIG. 8 is a partially enlarged view of FIG. [Figure 11] FIG. 7 is a front view of the slot die coater shown in FIG. [Figure 12] FIG. 7 is a perspective view showing an example of a shim that can be included in the slot die coater shown in FIG. [Figure 13] FIG. 2 is a perspective view showing a slot die coater according to another embodiment of the present invention. [Figure 14] This is a modified example of FIG. [Figure 15]FIG. 14 is a cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. [Figure 16] FIG. 15 is a cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. [Figure 17] FIG. 14 is a perspective view of a modified example of the slot die coater shown in FIG. 13, seen from another direction. [Figure 18] FIG. 14 is a perspective view showing an example of a shim that can be included in the slot die coater shown in FIG. 13. [Figure 19] FIG. 18 is a partially enlarged view of FIG. [Figure 20] FIG. 18 is a perspective view of the slot die coater shown in FIG. 17 from another direction. [Figure 21] This is a modified example of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] 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.

[0040] The same reference numerals refer to the same components. Also, in the drawings, thicknesses, ratios and dimensions of components are exaggerated for the purpose of effectively explaining technical contents.

[0041] FIG. 6 is a perspective view showing a slot die coater according to an embodiment of the present invention. FIG. 7 is a cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. 6, which corresponds to the cross-sectional view of the VII-VII′ arrows in FIG. 6 and shows a cross-section parallel to the discharge direction of the discharge port. FIG. 8 is a view of a modified example of the slot die coater shown in FIG. 7. FIG. 9 is another cross-sectional view perpendicular to the width direction of the slot die coater shown in FIG. 6, which corresponds to the cross-sectional view of the VIII-VIII′ arrows in FIG. 6 and shows a cross-section parallel to the discharge direction of the discharge port as in FIG. 6. FIG. 10 is a partially enlarged view of FIG. 7, and FIG. 11 is a front view of the slot die coater shown in FIG. 6.

[0042] As shown in FIG. 1, the existing slot die coater 1 is composed of two die blocks 10, 20 and a shim 60, whereas, as shown in FIGS. 6 to 11, the slot die coater 100 of the present invention is composed of an upper plate 110 (a modified structure), a lower plate 120, a shim 160, a taper block 180, and a pressure bolt 190.

[0043] The slot die coater 100 of the present invention is an apparatus that includes a slot 130 and coats a coating liquid on a substrate through the slot 130. The "substrate" described below is a current collector, and the "coating liquid" is an active material slurry. However, the scope of the present invention is not necessarily limited thereto. For example, the substrate may be a porous support constituting a separator, and the coating liquid may be an organic material. That is, the substrate and the coating liquid may be anything as long as a thin film coating is required. In this specification, "front" refers to the direction in which the discharge port faces (X-axis direction), and "rear" may refer to the opposite direction. "Left / right" refers to the direction perpendicular to the direction in which the discharge port faces, and may refer to the width direction of the slot (Y-axis direction).

[0044] 6 to 11, a slot die coater 100 according to an embodiment of the present invention is a slot die coater having a slot 130 for discharging a coating liquid, and includes an upper plate 110 and a lower plate 120. For example, if the slot die coater 100 is installed so that the X-axis direction, which is the direction of the discharge port 140, is the opposite direction to gravity, it can be realized as a vertical die that discharges the coating liquid in the opposite direction to gravity as intended.

[0045] The upper plate 110 and the lower plate 120 are assembled together to form a discharge port 140 that communicates with the slot 130. The upper plate 110 and the lower plate 120 may be assembled by a fixing bolt 170.

[0046] The upper plate 110 forms a slot 130 between itself and the lower plate 120. A shim 160 is interposed between the lower plate 120 and the upper plate 110 to form the slot 130 that communicates with the discharge port 140.

[0047] The upper plate 110 and the lower plate 120 are rectangular members whose width in the Y-axis direction perpendicular to the X-axis direction is longer than their length in the X-axis direction, which is the forward direction toward which the outlet port 140 faces. The shim 160 is in contact with the contact surfaces of the upper plate 110 and the lower plate 120, and can be assembled between the upper plate 110 and the lower plate 120 by a fixing bolt 170 that fastens the upper plate 110 and the lower plate 120 together.

[0048] The slot 130 is formed between the upper plate 110 and the lower plate 120, which face each other. The shim 160 is interposed between them to provide a gap, thereby forming the slot 130, which corresponds to a passage through which the coating liquid can flow. The thickness of the shim 160 determines the vertical width of the slot 130 (Z-axis direction, slot gap).

[0049] Most of the surfaces of the upper plate 110 and the lower plate 120 can be made to be approximately vertical. In such an upper plate 110 and a lower plate 120, the edges between the surfaces are formed at right angles, so that a right angle exists in a cross-sectional view, and a vertical or horizontal plane can be used as a reference surface, so that the plate can be easily made and handled, and the accuracy is guaranteed. In addition, when the upper plate 110 and the lower plate 120 are assembled, the facing portions can be supported by each other with a high degree of surface contact, so that the plate can be fastened and held very well. In addition, the assembled state of the upper plate 110 and the lower plate 120 has an approximately rectangular parallelepiped shape as a whole, and only the front portion from which the coating liquid is discharged can have a shape that is inclined toward the substrate.

[0050] The upper plate 110 and the lower plate 120 are, for example, made of SUS (stainless steel). Materials that are easy to process, such as SUS420J2, SUS630, SUS440C, SUS304, and SUS316L, can be used. SUS has the advantages of being easy to process, inexpensive, highly corrosion-resistant, and capable of being manufactured into a desired shape at low cost.

[0051] Generally, liquid leakage is likely to occur from the joining surface of a SUS assembly, so a rubber ring or other soft material is positioned between the components to seal and prevent liquid leakage. However, such a sealing method is not suitable for controlling a uniform assembly form (e.g., assembly deviation of less than 10 μm), so it is difficult to apply it to the slot die coater 100. For this reason, the slot die coater 100 assembles the upper plate 110 and the lower plate 120, which are processed with extremely high precision (straightness, flatness ±5 μm), by fastening them together with the fixing bolt 170. Since liquid leakage must be prevented, it is preferable to fasten the fixing bolt 170 with a high pressure of about 200 to 350 N.

[0052] The upper plate 110 has a groove H1 on the upper side of the slot 130, which is indented into the upper plate 110 in parallel with the shim 160. The taper block 180 and the pressing bolt 190 are inserted into the groove H1 to press the shim 160.

[0053] Thus, in the present invention, groove H1 into which taper block 180 can be inserted is machined in upper plate 110. Groove H1 is formed on the discharge port 140 side. In other words, groove H1 is formed on the front surface of upper plate 110. Groove H1 extends from the front surface to the rear surface of upper plate 110, i.e., recesses into the interior of upper plate 110.

[0054] The groove H1 may correspond to a recess in a portion of the upper plate 110, or to a cutting process of the upper plate 110. The groove H1 is preferably as small as necessary but as small as possible in size so as not to impair the mechanical rigidity of the upper plate 110. As shown in the figure, the groove H1 may be elongated in the width direction, but this is not necessarily limited thereto.

[0055] 7 and 8, a bolt groove H2 for fixing and pressing is machined on the upper plate 110. The bolt groove H2 may be formed so that a pressing bolt 190 is fastened to a position aligned with the groove H1. The pressing bolt 190 is fastened to the taper block 180 on the front surface of the upper plate 110. The operation of the pressing bolt 190 is performed on the front surface of the upper plate 110.

[0056] The taper block 180 and the pressing bolt 190 are positioned so as to be able to press the shim 160 against the portion of the shim 160 excluding both the left and right ends (sides). The pressing bolt 190 serves to fix the position of the taper block 180 in the groove H1, while at the same time generating a pressing force due to the height difference between the taper block 180 and the groove H1, enabling the shim 160 to be pressed against the groove H1.

[0057] The pressing force can be adjusted by adjusting the position of the taper block 180 according to the degree to which the pressing bolt 190 is tightened. The position of the taper block 180 is variable by the pressing bolt 190. In particular, the taper block 180 is fastened to the pressing bolt 190 and is movable back and forth in a direction parallel to the discharge direction of the discharge port. A hole O is formed in the taper block 180 in alignment with the bolt groove H2 so that the pressing bolt 190 can pass through.

[0058] 7, the bolt groove H2 is formed to have approximately the same diameter as the pressing bolt 190, and is threaded so that the pressing bolt 190 can be fastened. The bolt groove H2 is formed further inward than the groove H1, and is capable of fastening the end of the pressing bolt 190. The pressing bolt 190 is threaded up to the end.

[0059] 8 shows another example, in which the pressing bolt 190 has a threaded line formed only up to a certain length and the end is plain. A U-shaped hook with a through hole may be further included to be inserted across the bolt groove H2 so that the end of the pressing bolt 190 does not rotate freely in the bolt groove H2. The bolt groove H2 is formed wide at the rear end of the hook, so that the stress on the end of the pressing bolt 190 can be relieved.

[0060] A manifold 150 for containing the coating liquid may be provided on the lower plate 120. The manifold 150 may have a predetermined shape and depth. Although not shown, the manifold 150 is connected to a coating liquid supply chamber (not shown) disposed outside via a supply pipe to receive the coating liquid. When the manifold 150 is filled with the coating liquid, the flow of the coating liquid is guided along the slots 130 and discharged to the outside through the discharge port 140.

[0061] The manifold 150 is formed to uniformly supply / discharge a coating liquid such as an active material slurry onto a substrate such as a current collector. The manifold 150 may be disposed on the upper plate 110.

[0062] In the drawing, reference numerals 110a and 120a denote die lips which are the tips of the upper plate 110 and the lower plate 120.

[0063] 7 and 10, the groove H1 into which the taper block 180 can be inserted has a height h that gradually decreases as one advances toward the inside of the groove H1, i.e., from the front surface to the rear surface of the upper plate 110. The inclination of the taper block 180 can be adjusted accordingly. In other words, the groove H1 is formed so that the height h gradually decreases as one advances toward the inside of the upper plate 110, and the taper block 180 can also be formed in this manner.

[0064] The taper block 180 is designed to be movable in the front-rear direction in the groove H1 by the pressing bolt 190. For example, the taper block 180 may have a flat lower surface and an inclined upper surface as shown in the figure. Accordingly, the groove H1 may also have a flat lower surface and an inclined upper surface, so that the height h gradually decreases toward the inside of the groove H1.

[0065] By flattening the bottom surface of groove H1, groove H1 can be made parallel to shim 160. By flattening the bottom surface of taper block 180, a uniform force can be applied in the direction of shim 160. Although the height h can be made gradually smaller as one progresses from the front surface to the rear surface of top plate 110 by inclining both the top and bottom surfaces of groove H1 and taper block 180, by flattening the bottom surface, it becomes a reference surface for processing operations and manipulations, and groove H1 and taper block 180 can be processed with very high precision (straightness, flatness ±5 μm).

[0066] The pressing bolt 190 can be fastened to the upper plate 110 by passing through the taper block 180 from the front side of the groove H1. That is, the pressing bolt 190 can be operated on the front surface of the upper plate 110.

[0067] The more the pressing bolt 190 of the taper block 180 is tightened, that is, the more the taper block 180 moves inwardly into the groove H1 in the direction of the small arrow in FIG. 10, the more the force F shown by the thick arrow is applied vertically to that point. As the groove H1 advances inwardly, the height h gradually decreases, and the more the taper block 180 is pressed into this, the more the height difference between the groove H1 and the taper block 180 occurs, and a force that tries to push out in all directions is generated, which is equivalent to inserting a large object into a narrow gap. In this way, among the forces that the taper block 180 pushes in all directions to expand the groove H1 in all directions, the force F in the direction of pressing the shim 160 is particularly used. This force F tightens the gap between the upper plate 110, the shim 160, and the lower plate 120. The shim 160 can be tightened uniformly by the area BA of the lower surface of the taper block 180. Even under circumstances in which the internal pressure of the slot die coater 100 increases due to the ejection of coating liquid, a force F is applied by the tapered block 180 pressing the shim 160, thereby preventing distortion of the upper plate 110 and the lower plate 120 and preventing the ejection of active material slurry onto uncoated areas.

[0068] 7 and 8, the length D1 of the taper block 180 needs to be shorter than the length L of the land 120b. The land 120b refers to the region from the front end of the manifold 150 to the outlet 140. If the length D1 of the taper block 180 is longer than the length L of the land 120b, there is a risk that a portion of the manifold 150 will be affected.

[0069] Also, referring to FIG. 11, the horizontal length D2 of the taper block 180 needs not to be larger than the length S of the shim 160 in the width direction. If the horizontal length D2 of the taper block 180 is larger than the length S of the shim 160, there is a risk of affecting the slot gap G. In this way, the taper block 180 acts on the center portion of the upper plate 110 as well, and is not connected in an excessively long shape to such an extent that the taper block 180 affects the discharge port 140 in the width direction. The taper block 180 acts only on the portion of the shim 160 below it. The taper block 180 does not change the slot gap G.

[0070] FIG. 12 is a perspective view showing an example of a shim that can be included in the slot die coater shown in FIG.

[0071] 6 and 12 in combination, the shim 160 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 upper plate 110 and the lower plate 120 except for the area where the discharge port 140 is formed. The shim 160 may be made of, for example, plastic or metal, but the present invention is not limited thereto. The shim 160 may be, for example, a resin sheet such as Teflon or polyester, or a metal sheet such as copper or aluminum.

[0072] The shim 160 may be a one-piece structure with no seams. The shim 160 may have a flat top surface and a flat bottom surface, i.e., it may be a sheet-like member.

[0073] The shim 160 may be interposed in the remaining part of the peripheral region of the opposing surface between the upper plate 110 and the lower plate 120 except for one side. Therefore, the discharge port 140 through which the coating liquid can be discharged to the outside is formed between the die lips 110a, 120a. The discharge port 140 can be said to be a portion formed by the die lips 110a, 120a being spaced apart from each other, and the end of the slot 130 becomes the discharge port 140. The shim 160 has a plurality of openings 160a intermittently cut out at intervals in one region so as to determine the coating width of the coating layer applied on the substrate. The openings 160a limit the slot 130, and the end of the slot 130 becomes the discharge port 140. If there is a single opening 160a, a single coating layer can be formed, and if there are two openings 160a as shown in the figure, two coating layers can be formed lined up side by side along the Y-axis direction.

[0074] For example, the shim 160 may include a plurality of extension portions 162 that are vertically connected to a base portion 161 and extend toward the outlet 140 to include a plurality of openings 160a. The width of the openings 160a of the shim 160 is designed to be b so that a plurality of active material layers having a coating width b are formed on the substrate and uncoated portions are formed on both sides of each active material layer. When the shim 160 as shown in FIG 12 is applied, a coating layer in a stripe pattern is formed on the substrate.

[0075] 11, the taper block 180 may be disposed at a position corresponding to the extending portions 162 excluding the extending portions at the ends (sides) of the multiple extending portions 162. In particular, the horizontal length D2 of the taper block 180 is not larger than the length S of the extending portions 162 of the shim 160, particularly the extending portion 162 located at the center, and the taper block 180 may be inserted into the groove H1 at a position corresponding to such extending portions 162 and press the extending portion 162 at that portion. In addition, by adjusting the length D1 of the taper block 180, the taper block 180 presses the portion of the land 120b without affecting the manifold 150. The taper block 180 has a size that does not intrude into the openings 160a on both sides of the extension portion 162 at a position corresponding to the extension portion 162, so the taper block 180 and the pressing bolt 190 can press the shim 160 without affecting the openings 160a. By pressing the shim 160, the upper plate 110 and the lower plate 120 can be prevented from spreading apart.

[0076] The shim 160 is positioned below the taper block 180. Since the shim 160 receives the upper plate 110, the opening 160a is not affected even when the taper block 180 is operated, and therefore the slot gap G is not distorted. In other words, the flow rate of the coating liquid through the discharge port 140 does not change even when the taper block 180 is operated. The present invention does not aim to change the slot gap G and does not affect the slot gap G.

[0077] Conventionally, there was a problem that the die lips 10a, 20a would widen when the internal pressure of the slot die coater 1 increased (see Figs. 1 to 5). However, according to the present invention, the taper block 180 clamps the gap between the upper plate 110, the shim 160, and the lower plate 120, so that the die lips 110a, 120a do not widen. Furthermore, the active material slurry does not get into areas that should be blocked to prevent the active material slurry from being discharged. Therefore, it is possible to form a pattern of an electrode active material layer without surface defects caused by the active material slurry adhering to the non-coated areas.

[0078] At the rear and front sides of the manifold 150, the lower surface of the upper plate 110 and the upper surface of the shim 160 can be joined together without any gaps, and the upper surface of the lower plate 120 and the lower surface of the shim 160 can be joined together without any gaps. In particular, the upper plate 110, the shim 160, and the lower plate 120 can be further pressed together via the taper block 180 and the pressing bolt 190 to prevent the upper plate 110 and the lower plate 120 from spreading. As a result, the coating liquid flows firmly only within the slot 130 defined by the shim 160, and does not invade the uncoated portions.

[0079] According to the slot die coater 100 having such a configuration, a rotatable coating roll (not shown) is disposed in front of the slot die coater 100, and the coating roll is rotated to discharge the coating liquid and continuously contact the surface of the substrate while the substrate to be coated is traveling, thereby coating the substrate. Alternatively, the supply of the coating liquid can be alternately started and stopped to form a pattern coating on the substrate at intervals. Since the coating liquid does not penetrate the uncoated portions, a coating layer can be formed without pattern defects.

[0080] For example, the slot die coater 100 of the present invention can be used to coat a positive electrode active material slurry, thereby making it possible to apply the present invention to the manufacture of a positive electrode for a secondary battery. The positive electrode includes a current collector and a positive electrode active material layer formed on the surface of the current collector. The current collector is made of Al, Cu, or the like, and is electrically conductive. Any appropriate current collector can be used according to the polarity of the current collector electrode known in the field of secondary batteries. The positive electrode active material layer may further include one or more of a plurality of positive electrode active material particles, a conductive material, and a binder. The positive electrode may further include various additives for the purpose of complementing or improving electrochemical characteristics.

[0081] The active material is not limited to any particular component as long as it can be used as a positive electrode active material for a lithium ion secondary battery. Non-limiting examples include layered compounds such as lithium manganese composite oxides (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), and lithium nickel oxide (LiNiO2), as well as compounds substituted with one or more transition metals, and compounds of the general formula Li 1+x Mn 2-x Lithium manganese oxides such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, and Cu2V2O7; and oxides of the general formula LiNi 1-x M x O2 (where M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x=0.01 to 0.3), and LiMn 2-x M x The positive electrode may include one or a mixture of two or more of a lithium manganese composite oxide represented by Li2Mn3MO8 (wherein M=Co, Ni, Fe, Cr, Zn, or Ta, and x=0.01 to 0.1) or Li2Mn3MO8 (wherein M=Fe, Co, Ni, Cu, or Zn), LiMn2O4 in which part of Li in the general formula is substituted with an alkaline earth metal ion, a disulfide compound, and Fe2(MoO4)3. In the present invention, the positive electrode may include, as a solid electrolyte material, one or more of a polymer-based solid electrolyte, an oxide-based solid electrolyte, and a sulfide-based solid electrolyte.

[0082] The conductive material may be added in an amount of 1 wt% to 20 wt% based on the total weight of the mixture containing the active material. Such a conductive material is not particularly limited as long as it does not induce chemical changes in the battery and has conductivity, and examples thereof include graphite such as natural graphite and artificial graphite, carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, conductive fibers such as carbon fibers and metal fibers, metal powders such as carbon fluoride, aluminum, and nickel powder, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive materials such as polyphenylene derivatives, or a mixture of two or more kinds.

[0083] The binder is not particularly limited as long as it is a component that aids in binding between the active material and the conductive material and to the current collector, and examples thereof include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, various copolymers, etc. The binder may usually be contained in a range of 1 wt% to 30 wt%, or 1 wt% to 10 wt%, based on 100 wt% of the electrode layer.

[0084] The slot die coater 100 of the present invention can be used to coat the negative electrode active material slurry, thereby making it possible to manufacture a negative electrode for a secondary battery. The negative electrode includes a current collector and a negative electrode active material layer formed on the surface of the current collector. The negative electrode active material layer may further include one or more of a plurality of negative electrode active material particles, a conductive material, and a binder. The negative electrode may further include various additives for the purpose of complementing or improving electrochemical characteristics.

[0085] The negative electrode active material may be a carbon material such as graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotube, or carbon nanohorn, a lithium metal material, an alloy material such as silicon or tin, Nb2O5, Li5Ti4O 12 For the negative electrode, oxide-based materials such as TiO2, or a composite of these can be used. For the conductive material, binder, and current collector, refer to the contents described for the positive electrode.

[0086] Such an active material slurry containing a positive electrode active material or a negative electrode active material has a very high viscosity. For example, the viscosity may be 1000 cps or more. The viscosity of the active material slurry for use in forming an electrode of a secondary battery may be 2000 cps to 30000 cps. For example, the viscosity of the negative electrode active material slurry may be 2000 cps to 4000 cps. The viscosity of the positive electrode active material slurry may be 8000 cps to 30000 cps. Since the slot die coater 100 of the present invention must be capable of coating a coating liquid having a viscosity of 1000 cps or more, the structure of the slot die coater 100 of the present invention is different from that of a device for applying a coating liquid having a lower viscosity than this, for example, a photosensitive emulsion liquid, a magnetic liquid, a liquid that provides anti-reflection or anti-glare properties, a liquid that provides a viewing angle widening effect, a pigment liquid for a color filter, and other ordinary resin liquids, and is not a device that can be conceived by changing the structure. The slot die coater 100 of the present invention is for applying an active material slurry that may contain an active material having an average particle size of about 10 μm, and therefore has a different structure from that of an apparatus for applying other coating liquids that do not contain particles of such a particle size, and is not an apparatus that can be conceived by modifying the apparatus. The slot die coater 100 of the present invention is optimized as a coater for producing electrodes.

[0087] When discharging a coating liquid such as a highly viscous active material slurry, a force may be applied around the discharge port 140 due to the discharge pressure. Conventionally, there was a problem that the active material slurry penetrated into the inside of the die blocks 10, 20 other than the shim 60 due to distortion of the die blocks 10, 20, causing pattern defects (see Figs. 1 to 5). According to the present invention, the tapered block 180 and the pressing bolt 190 are provided, so that distortion of the upper plate 110 and the lower plate 120 is prevented, and the coating liquid such as the active material slurry cannot penetrate into the inside of the slot die coater 100 outside the width defined by the shim 160, for example, "b" in Fig. 12. Therefore, a good active material layer can be formed without pattern defects.

[0088] According to the present invention, the coating liquid does not penetrate into unnecessary parts inside the slot die coater 100. Therefore, there is no concern that the active material slurry will splash and cause contamination of the boundary when coating the uncoated parts, or cause unevenness of the boundary such as a wavy pattern on the boundary. Only when the boundary of the coating formed in the MD direction is uniformly formed, slitting defects will not occur when slitting along the uncoated parts to form electrodes on each active material layer later, and even if it should happen, the electrode will not break after manufacturing the secondary battery due to contamination remaining in the uncoated parts. When the slot die coater 100 according to the present invention is used, slitting defects and electrode breakage will not occur.

[0089] According to the present invention, the structure of the upper plate 110 is modified from the conventional one, and further includes a taper block 180 and a pressing bolt 190. The taper block 180 and the pressing bolt 190 tightly press the upper plate 110, the shim 160, and the lower plate 120 together, so that the upper plate 110, the shim 160, and the lower plate 120 are in contact with each other, and a gap is unlikely to occur between them. As a result, even if torque is generated due to the internal pressure of the slot die coater 100, the upper plate 110 and the lower plate 120 can support the surfaces that abut against each other with the shim 160 sandwiched therebetween. In other words, the slot 130 can be prevented from widening. If the active material slurry flows in while the upper plate 110 and the lower plate 120 spread apart, the active material slurry will intermittently adhere to the uncoated areas, causing surface defects. However, in the slot die coater 100 according to the present invention, the upper plate 110 and the lower plate 120 do not spread apart, making it possible to form an electrode without surface defects.

[0090] FIG. 13 is a perspective view showing a slot die coater according to another embodiment of the present invention, and FIG. 14 is a view of a modified example. FIG. 15 and FIG. 16 are cross-sectional views perpendicular to the width direction of the slot die coater shown in FIG. 13 and FIG. 14, respectively, and correspond to the cross-sections seen from the arrows XIII-XIII' in FIG. 13 and FIG. 14. FIG. 17 is a perspective view from another direction of a modified example of the slot die coater shown in FIG. 13, showing the front of the slot die coater. FIG. 18 is a perspective view showing an example of a shim that can be included in the slot die coater shown in FIG. 13. FIG. 19 is a partially enlarged view of FIG. 17. FIG. 20 is a perspective view from another direction of the slot die coater shown in FIG. 17, showing the rear of the slot die coater. FIG. 21 is a modified example of FIG. 20.

[0091] A slot die coater according to another embodiment of the present invention will now be described with reference to the above drawings.

[0092] Compared to the above-described slot die coater 100, the slot die coater 200 according to another embodiment of the present invention does not have the bolt groove H2 for fixing and pressing the taper block 180 that was present on the upper plate 110, and instead has a long hole H3 machined in the width direction at that position.

[0093] The long hole H3 is formed in the rear surface of the upper plate 110 so as to be elongated in the width direction so that the pressure bolt 190 can be inserted therein.

[0094] The pressing bolt 190 penetrates the upper plate 110 from the rear surface thereof and is fastened to the taper block 180. That is, the pressing bolt 190 is inserted from the rear surface of the upper plate 110 and penetrates into the taper block 180. For this purpose, a thread is machined in the taper block 180 to which the pressing bolt 190 can be fastened. The difference from the previous embodiment is that the pressing bolt 190 is fastened to the taper block 180 at the rear surface of the upper plate 110. The pressing bolt 190 is operated at the rear surface of the upper plate 110. Since the pressing bolt 190 is operated at the rear portion, not at the front portion where the coating liquid is discharged, it is much easier to manage the work, maintenance, and the like.

[0095] The long hole H3 is formed elongated in the width direction, and the pressing bolts 190 can be added in accordance with the number of patterns to be formed, and the taper blocks 180 can be added in a corresponding number to the grooves H1 formed in the front surface of the upper plate 110. In other words, each pattern can be separately configured.

[0096] 13 and 15, the long hole H3 is formed to have approximately the same size as the diameter of the pressing bolt 190. The pressing bolt 190 is plain and has a threaded line at its end. The cross-sectional shape of the long hole H3 and the shape of the pressing bolt 190 are not limited to the shapes shown in the drawings, and can be modified without any particular restrictions. The long hole H3 is formed in a long shape in the width direction on the back surface of the upper plate 110. This is a mechanism that makes it easy to position the pressing bolt 190 at any position in the long hole H3.

[0097] 14 and 16, which are modified examples, the long hole H3 is formed to be larger in diameter than the pressing bolt 190. To prevent the pressing bolt 190 from spinning freely within such long hole H3, the middle of the front surface of the long hole H3 and the back surface of the upper plate 110 are closed to act as a hook. The long hole H3 is formed wider than in the previous embodiment, and is designed to prevent the fastening stress from the pressing bolt 190 from being applied to the upper plate 110.

[0098] 17, 20 and 21 show in detail an example in which there are two taper blocks 180. A shim 160 that can be used in this case is shown in FIG.

[0099] 18, the shim 160 may include four extension parts 162 that are connected perpendicularly to a base part 161 so as to include three opening parts 160a and extend towards the discharge port 140. The taper block 180 is arranged to correspond to the remaining two extension parts 162, excluding both the left and right ends (sides), out of the four extension parts 162.

[0100] Thus, according to another embodiment of the present invention, the number of taper blocks 180 can be increased and their positions can be changed to match the positions of the shims 160. Therefore, a plurality of pressing bolts 190 and taper blocks 180 can be provided along the width direction. Note that, when the shape of the shim 160 is changed, the positions of the taper blocks 180 and the pressing bolts 190 can be changed to desired positions in the width direction.

[0101] 19, the taper block 180 and the pressing bolt 190 do not affect the slot gap G, so the slot gap G can be maintained to correspond to the set thickness H of the shim 160. That is, in the present invention, the size of the slot gap G is adjusted to the thickness H of the shim 160, and the taper block 180 and the pressing bolt 190 press the shim 160 without affecting the slot gap G, preventing the upper plate 110 and the lower plate 120 from widening.

[0102] A plurality of taper blocks 180 may be provided in the width direction. When a plurality of taper blocks 180 are provided and the intervals between them are adjusted to be uniform, the force can be transmitted more uniformly and a stable balance state can be achieved, thereby preventing distortion of the upper plate 110 and the lower plate 120.

[0103] The die lips 110a, 120a do not expand due to the taper block 180 and the pressing bolt 190. Therefore, the active material slurry does not get into the part of the shim 160 that should block the active material slurry to prevent it from being discharged.

[0104] Meanwhile, in the above embodiment, the slot die coaters 100 and 200 have been described as being of a vertical die type that discharges the active material slurry, which is the coating liquid, in the direction opposite to gravity, but the present invention can also be applied to a horizontal die type in which the discharge port 140 is disposed substantially horizontally (approximately ±5°). Note that the slot die coaters 100 and 200 have been described as having a single layer of slots 130 between the upper plate 110 and the lower plate 120, but the present invention can also be realized by a dual slot die coater in which the slots are formed in two layers including the upper plate, the middle plate, and the lower plate.

[0105] 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]

[0106] 100, 200 Slot Die Coater 110 Upper Plate 110a, 120a die lip 120 Lower plate 120b Land 130 Slots 140 Discharge port 150 Manifold 160 Sim 170 Fixing bolt 180 Taper Block 190 Press bolt

Claims

1. an upper plate and a lower plate which are combined with each other to form a discharge port; a shim interposed between the lower plate and the upper plate to form a slot communicating with the outlet; Including, the upper plate has a groove on an upper side of the slot, the groove extending inwardly of the upper plate and parallel to the shim; The slot die coater further includes a taper block and a pressure bolt that are inserted into the groove and press against the shim.

2. 2. The slot die coater of claim 1, wherein the groove has a height that gradually decreases toward the inside of the groove, and the inclination of the tapered block is adjusted thereto.

3. The slot die coater according to claim 1 , wherein the pressing bolt penetrates the taper block from a front side of the groove and is fastened to the upper plate.

4. The slot die coater according to claim 1 , wherein the groove is indented from the front surface to the rear surface of the upper plate, and the pressing bolt is fastened to the taper block at the front surface of the upper plate.

5. 2. The slot die coater according to claim 1, wherein the taper block is fastened to the pressure bolt and moves back and forth in a direction parallel to the discharge direction of the discharge port, generating a force due to a height difference between the groove and the taper block to press the shim.

6. 2. The slot die coater of claim 1, wherein the shim includes a plurality of extension portions that are connected perpendicularly to a base portion so as to include a plurality of open portions and extend toward the discharge outlet side, the horizontal length of the taper block is not greater than the horizontal length of the extension portions, and the taper block is inserted into the groove at a position corresponding to the extension portions.

7. The slot die coater according to claim 6 , wherein the taper block is disposed at a position corresponding to each of the plurality of extension portions excluding the extension portions at the ends.

8. The slot die coater of claim 1, further comprising a manifold on the lower plate, and the length of the taper block is shorter than the length of a land, which is the region from the front end of the manifold to the discharge port.

9. The slot die coater according to claim 1 , wherein the groove is formed on the discharge port side.

10. The slot die coater according to claim 1 , further comprising a bolt groove for fastening the pressing bolt at a position aligned with the groove.

11. The slot die coater according to claim 10 , wherein the taper block is formed with a hole aligned with the bolt groove so that the pressing bolt can pass through.

12. The slot die coater according to claim 1 , wherein the pressing bolt penetrates the upper plate from a rear surface of the upper plate and is fastened to the taper block.

13. The slot die coater according to claim 12, further comprising a long hole in a width direction of a rear surface of the upper plate so that the pressing bolt can be inserted therein.

14. The slot die coater according to claim 13, wherein a plurality of the pressing bolts and the taper blocks are arranged along the width direction.

15. The slot die coater according to claim 1 , wherein a threaded line to which the pressing bolt can be fastened is formed in the taper block.

16. 14. The slot die coater of claim 13, wherein the long hole is formed from the back surface of the upper plate toward the front surface, the groove is formed from the front surface of the upper plate toward the back surface, and the long hole is formed at a position aligned with the groove.

17. The slot die coater of claim 1 , wherein the lower plate is provided with a manifold that contains a coating fluid, the manifold communicating with the slot.

18. 18. The slot die coater according to claim 17, wherein the slot die coater applies the coating liquid by ejecting it onto the substrate through the outlet, and the shim has a plurality of openings in which one area is intermittently cut out so as to determine a coating width of the coating layer applied onto the substrate.

19. 20. The slot die coater of claim 18, wherein the taper block and the pressure bolt press the shim without affecting the opening to prevent the upper plate and the lower plate from spreading apart.

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