Multislot die coater

Abstract

A multi-slot die coater having reduced structural vulnerability to deformation and distortion in a multi-slot die coater including substantially three die blocks is provided. The multi-slot die coater according to the present invention is a multi-slot die coater including a lower slot and an upper slot to extrude and coat a coating solution on a surface of a continuously moving substrate through at least one of the lower slot or the upper slot, and including a lower die block, a middle die block, and an upper die block. The multi-slot die coater includes a bolt fastened at a contact surface between the lower die block, the middle die block, and the upper die block, the bolt being angled such that a bolt head faces upward toward an upper outlet port and a lower outlet port.

Description

Technical Field

[0001] This application relates to a multi-slit mold coating machine capable of simultaneously forming two or more layers using a wet process, and more particularly, to a multi-slit mold coating machine having suppressed deformation and torsion caused by structural features comprising a thin mold. This application claims priority to Korean Patent Application No. 10-2020-0126044, filed in Korea on September 28, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0002] With technological advancements and the growing demand for mobile devices, the need for secondary batteries as an energy source is rapidly increasing. These secondary batteries essentially consist of electrode assemblies that function as power generation elements. The electrode assemblies include a positive electrode, a separator, and a negative electrode stacked at least once. The positive and negative electrodes are manufactured by coating current collectors made of aluminum foil and copper foil, respectively, with positive and negative active material slurries and then drying them. For uniform charge / discharge characteristics of the secondary battery, it is necessary to uniformly coat the positive and negative active material slurries onto the current collector, and a slot die coating machine has been used.

[0003] Electrode manufacturing methods using a slot die coating machine involve coating an electrode active material slurry flowing from the slot die coating machine onto a current collector moving via a coating roller. A conventional slot die coating machine comprises two dies and a slot between them, and can dispense one type of electrode active material slurry through a single slot to form an electrode active material layer.

[0004] To manufacture high-energy-density rechargeable batteries, the thickness of the electrode active material layer gradually increases from approximately 130 μm to 300 μm. When forming a thick electrode active material layer using a conventional slit-die coating machine, the binder and conductive materials in the active material slurry migrate rapidly during drying, resulting in an unevenly manufactured electrode. To address this issue, forming a thin electrode active material layer, drying it, and repeating the process requires a long time for two coating operations. To improve electrode performance and productivity, the inventors have proposed a dual-slit-die coating machine capable of simultaneously coating two types of electrode active material slurries.

[0005] Figure 1 This is a schematic cross-sectional view of a double-slit mold coating machine based on relevant technologies.

[0006] Reference Figure 1By coating two types of electrode active material slurries from a dual-slit die coater 20 while rotating the coating roller 10 to move the current collector 15, two electrode active material layers can be formed simultaneously on the current collector 15. The electrode active material slurry exiting the dual-slit die coater 20 is coated on one surface of the current collector 15 to form an electrode active material layer.

[0007] The dual-slit mold coating machine 20 is constructed by assembling three plate components (i.e., three mold blocks 21, 22, and 23). Slits are formed between adjacent mold blocks, thus creating two slits. Two types of electrode active material slurries are simultaneously dispensed through outlet ports 24 and 25, each outlet port communicating with each slit. Therefore, two electrode active material layers can be formed simultaneously by continuously coating another electrode active material slurry onto an electrode active material layer formed by a previously coated electrode active material slurry. Reference numerals 26 and 27 indicate manifolds containing the coating solution.

[0008] However, due to the use of electrode active material slurry flowing out simultaneously from different outlet ports 24 and 25, it is difficult to form each electrode active material layer of the required thickness using the method of the dual slit die coating machine 20.

[0009] Typically, the thickness of each electrode active material layer is affected by the amount of electrode active material slurry flowing out through outlet ports 24, 25, and the amount of outflowing electrode active material slurry is significantly affected by the size (slit gap) of each outlet port 24, 25. Therefore, to achieve the desired thickness, conventional techniques require repeated testing of the coating process, disassembling and reassembling mold blocks 21, 22, 23, adjusting the slit gap, and checking the amount of outflowing electrode active material slurry. However, the slit gap is a variable that is adjusted so sensitively that the coating gap varies greatly depending on the tightening strength of the bolts used to assemble mold blocks 21, 22, 23, and can be altered by the force applied when electrode active material slurry appears. In particular, to achieve stable and uniform coating in the width direction (TD direction) along the current collector's movement direction (MD direction), uniform dimensional accuracy in the width direction is required, and it becomes even more difficult to uniformly control the slit gap in the width direction when the width of the dual-slit mold coating machine 20 is increased to use a wide current collector to increase production.

[0010] Since the dual-slit die coating machine 20 essentially comprises three die blocks 21, 22, and 23, in order to configure it with a similar footprint and volume to a conventional slit die coating machine comprising a single slit, the thickness of each die block 21, 22, and 23 needs to be reduced. Therefore, it is inevitably prone to structural deformation and twisting. When deformation or twisting occurs, the adjusted slit gap changes, leading to defects in the electrode process. Furthermore, this problem becomes even more pronounced for multi-slit die coating machines comprising two or more slits, due to the increased number of die blocks.

[0011] To address this issue, as the dimensions (angle changes) of each mold block 21, 22, and 23 increase, the orientation of the slurry changes, leading to reduced coating processability. Furthermore, among the three mold blocks 21, 22, and 23, even when the thickness of the outer mold blocks 21 and 23 is increased to prevent deformation and twisting, it remains difficult to prevent deformation of the structurally weakest middle mold block 22.

[0012] Meanwhile, each mold block 21, 22, 23 can be assembled by bolting at the contact surface. However, each mold block 21, 22, 23 is prone to deformation due to its thinness, and bolt tightening is easily deformed by large forces, so care is required. When the mold blocks 21, 22, 23 are moved between them by the force applied during tightening, this movement affects the coating gap, i.e., the distance between the outlet ports 24, 25 and the collector 15, resulting in uneven coating. Summary of the Invention

[0013] Technical issues

[0014] The present invention aims to solve the above-mentioned problems, and therefore aims to provide a multi-slit mold coating machine that has reduced structural fragility due to deformation and torsion in a multi-slit mold coating machine that basically includes three mold blocks.

[0015] However, the technical problems to be solved by the present invention are not limited to those described above, and those skilled in the art will clearly understand from the following description of the invention that are not mentioned.

[0016] Technical solution

[0017] To solve the above-mentioned technical problems, the multi-slit mold coating machine according to the present invention is a multi-slit mold coating machine including a lower slit and an upper slit, for extruding and coating a coating solution onto the surface of a continuously moving substrate through at least one of the lower slit or the upper slit. The multi-slit mold coating machine includes: a lower mold block; an intermediate mold block located on the lower mold block such that a lower slit is formed between the intermediate mold block and the lower mold block; and an upper mold block located on the intermediate mold block such that an upper slit is formed between the upper mold block and the intermediate mold block, wherein the lower mold block and the intermediate mold block... The upper mold block has a lower mold lip, a middle mold lip, and an upper mold lip. The lower mold lip, the middle mold lip, and the upper mold lip respectively form the front ends of the lower mold lip, the middle mold lip, and the upper mold lip. A lower outlet port communicating with the lower slit is formed between the lower mold lip and the middle mold lip, and an upper outlet port communicating with the upper slit is formed between the middle mold lip and the upper mold lip. The multi-slit mold coating machine includes bolts fastened to the contact surfaces between the lower mold block, the middle mold block, and the upper mold block. The bolts are at a certain angle, such that the bolt heads face the upper outlet port and the lower outlet port.

[0018] The angle between the contact surface and the bolt axis can be within the range of 70±10°.

[0019] The contact surface between the upper mold block and the intermediate mold block can be inclined, and the bolts can be tightened to the contact surface at an angle range of 70±10°.

[0020] The intermediate mold block may include a first intermediate mold block and a second intermediate mold block that are in surface contact with each other at an upper position and a lower position. The first intermediate mold block and the second intermediate mold block are slidably disposed along the contact surface to move relative to each other. The first intermediate mold block may be fixed and coupled to the lower mold block, and the second intermediate mold block may be fixed and coupled to the upper mold block.

[0021] A predetermined step can be formed between the lower exit port and the upper exit port.

[0022] The multi-slit mold coating machine may also include a first spacer and a second spacer. The first spacer is placed between the lower mold block and the middle mold block to adjust the width of the lower slit, and the second spacer is placed between the middle mold block and the upper mold block to adjust the width of the upper slit.

[0023] The lower mold block may include a first manifold containing a first coating solution, the first manifold being connected to a lower slit; the middle mold block may include a second manifold containing a second coating solution, the second manifold being connected to an upper slit.

[0024] The lower and upper slits can form an angle of 30° to 60°.

[0025] In the multi-slit mold coating machine according to the present invention, the bolt head of the bolt can protrude beyond the upper mold block.

[0026] The bolt legs of the bolt may include a threaded portion near the intermediate mold block and a smooth portion near the upper mold block, and the upper mold block and the intermediate mold block may have bolt holes aligned with each other to accommodate the bolt.

[0027] Beneficial effects

[0028] According to one aspect of the invention, bolts are tightened at the contact surfaces between the mold blocks at an angle such that the bolt heads face the downward and upward exit ports. The bolts tightened at an angle according to the invention can minimize deformation of the mold blocks.

[0029] In particular, according to one aspect of the invention, the mold blocks can be aligned linearly on the left and right sides in the width direction of the multi-slit mold coating machine. Therefore, when the multi-slit mold coating machine is installed by assembling the mold blocks, variations in the coating gap can be reduced. Furthermore, slit gap deviations can be suppressed. Thus, according to the invention, lateral filling uniformity can be ensured, thereby improving coating quality.

[0030] According to one aspect of the invention, the structural vulnerability of the mold blocks to deformation or twisting can be reduced, thereby uniformly forming a coating, particularly an electrode active material layer, of the desired thickness. Furthermore, at least two types of electrode active material slurries can be coated simultaneously, achieving high performance and high productivity. Deformation during clamping between mold blocks can be prevented, ensuring coating processability and reproducibility. When the multi-slit mold coating machine of the present invention is used to coat current collectors with electrode active material slurries in the manufacture of electrodes for secondary batteries, uniform coating can be achieved under high-speed or large-scale coating conditions.

[0031] According to another aspect of the invention, the bolt head is not embedded in the upper mold block, but protrudes beyond it. Even if there are tolerances in the holes used for bolt fastening, impurities can be prevented from entering the holes because the bolt head closes them. Therefore, imbalance of the bolt fastening assembly caused by impurities introduced into the holes can be prevented, and deformation of each mold block can be avoided. Attached Figure Description

[0032] The accompanying drawings illustrate preferred embodiments of the invention and, together with the detailed description of the invention, serve to provide a further understanding of the technical features of the invention; therefore, the invention is not to be construed as limited to the drawings.

[0033] Figure 1 This is a schematic cross-sectional view of a double-slit mold coating machine based on relevant technologies.

[0034] Figure 2This is a schematic cross-sectional view of a multi-slit mold coating machine according to an embodiment of the present invention.

[0035] Figure 3 This is a schematic exploded perspective view of a multi-slit mold coating machine according to an embodiment of the present invention.

[0036] Figure 4 This is a cross-sectional view showing the bolt fastening between mold blocks in a multi-slit mold coating machine according to an embodiment of the present invention.

[0037] Figure 5 It shows a cross-sectional view of a bolt fastening arrangement opposite to the present invention, such that the bolt head does not face the outlet port.

[0038] Figure 6 It shows that Figure 5 The direction of the force applied to the mold block by the bolt tightening angle.

[0039] Figure 7 This is a cross-sectional view of a multi-slit mold coating machine according to another embodiment of the present invention.

[0040] Figure 8 The image shows a photographic image illustrating the alignment between mold blocks using bolt fastening, which is contrary to the present invention, so that the bolt heads do not face the outlet port.

[0041] Figure 9 This is a photographic image showing the alignment between mold blocks according to the invention, where bolts are used to fasten the bolt heads toward the outlet port.

[0042] Figure 10 This is a cross-sectional view showing the bolt fastening between mold blocks in a multi-slit mold coating machine according to another embodiment. Detailed Implementation

[0043] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. Before description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but rather are interpreted based on the principle that inventors are allowed to appropriately define terms for the best interpretation, and on the meanings and concepts corresponding to the technical aspects of the invention. Therefore, the embodiments described herein and the illustrations in the drawings are merely some preferred embodiments of the invention and do not fully describe the technical features of the invention. It should be understood that various other equivalents and modifications can be made thereto when filing a patent application.

[0044] A multi-slit mold coating machine according to an embodiment of the present invention may include two or more slits. Essentially, a multi-slit mold coating machine is an apparatus comprising a lower slit and an upper slit to coat a coating solution in a double layer onto a substrate. The “substrate” described below is a current collector, and the coating solution is an “electrode active material slurry.” Both the first and second coating solutions are electrode active material slurries, and they may have the same or different compositions (types of active materials, conductive materials, and binders), amounts (quantities of active materials, conductive materials, and binders), or properties. The multi-slit mold coating machine according to an embodiment of the present invention is optimized for electrodes manufactured by simultaneously coating at least two types of electrode active material slurries or by pattern coating at least two types of electrode active material slurries in an alternating manner. However, the scope of the invention is not necessarily limited thereto. For example, the substrate may be a porous support for a diaphragm, and the first and second coating solutions may be organic materials with different compositions or properties. That is, when thin-film coating is required, the substrate, the first coating solution, and the second coating solution are not limited to specific types.

[0045] Figure 2 This is a schematic cross-sectional view of a multi-slit mold coating machine according to an embodiment of the present invention. Figure 3 This is a schematic exploded perspective view of a multi-slit mold coating machine according to an embodiment of the present invention.

[0046] The multi-slit mold coating machine 100 according to an embodiment of the present invention is a double-slit mold coating machine including a lower slit 101 and an upper slit 102, and is an apparatus capable of simultaneously or alternately coating the same type of coating solution or two different types of coating solutions onto a substrate 300 through the lower slit 101 and the upper slit 102. (Reference) Figure 2 and Figure 3 The multi-slit die coating machine 100 includes a lower die block 110, an intermediate die block 120 located on the lower die block 110, and an upper die block 130 located on the intermediate die block 120. The lower die block 110, the intermediate die block 120, and the upper die block 130 are assembled to each other by fasteners (e.g., bolts), and will be described in detail below.

[0047] The lower mold block 110 is the lowest of the multiple blocks in the multi-slit mold coating machine 100, and its surface facing the intermediate mold block 120 is inclined relative to the bottom surface (XZ plane) or the horizontal plane. According to an embodiment, the surface of the lower mold block 110 facing the intermediate mold block 120 can be almost parallel to the horizontal plane.

[0048] Reference Figure 2 and Figure 3The lower slit 101 can be formed in the area where the lower mold block 110 and the intermediate mold block 120 contact each other. For example, a first spacer 113 is placed between the lower mold block 110 and the intermediate mold block 120 to form a gap between the lower mold block 110 and the intermediate mold block 120, wherein the lower slit 101 corresponding to the channel through which the first coating solution 50 flows can be formed. In this case, the thickness of the first spacer 113 determines the vertical width of the lower slit 101 (Y-axis direction, slit gap). However, conventionally, it is difficult to maintain the slit gap because the mold blocks are susceptible to deformation and torsion.

[0049] like Figure 3 As shown, the first spacer 113 has a first opening 113a, which is cut in one region and can be placed in the remaining portion except for one side of the edge region of the facing surface of each of the lower mold block 110 and the intermediate mold block 120. Therefore, the lower outlet port 101a through which the first coating solution 50 passes is formed only between the front ends of the lower mold block 110 and the intermediate mold block 120. The front ends of the lower mold block 110 and the intermediate mold block 120 are defined as the lower mold lip 111 and the intermediate mold lip, respectively; in other words, the lower outlet port 101a is formed by the gap between the lower mold lip 111 and the intermediate mold lip.

[0050] For reference, the first spacer 113 serves as a gasket to prevent the first coating solution 50 from leaking through the gap between the lower mold block 110 and the intermediate mold block 120, except for the area forming the lower outlet port 101a. Therefore, the first spacer 113 is preferably made of a material with sealing capabilities.

[0051] The lower mold block 110 includes a first manifold 112 having a predetermined depth on its surface facing the intermediate mold block 120, the first manifold 112 communicating with the lower slit 101. Although not shown in the figures, the first manifold 112 is connected by a supply pipe to a first coating solution supply chamber (not shown) mounted externally, and is supplied with a first coating solution 50. When the first manifold 112 is completely filled with the first coating solution 50, the flow of the first coating solution 50 is guided along the lower slit 101 and flows out from the lower outlet port 101a.

[0052] The intermediate mold block 120 is a block located between multiple blocks of the multi-slit mold coating machine 100, and is positioned between the lower mold block 110 and the upper mold block 130 to form a double slit. Although the cross-section of the intermediate mold block 120 in this embodiment is a right-angled triangle, the shape is not limited to this, and the cross-section of the intermediate mold block 120 can be, for example, an isosceles triangle.

[0053] The upper mold block 130 is positioned to contact the upper surface of the intermediate mold block 120, which is nearly parallel to the horizontal plane. An upper slit 102 is formed in the region where the intermediate mold block 120 and the upper mold block 130 contact each other. According to an embodiment, the upper surface of the intermediate mold block 120 may be inclined relative to the horizontal plane, and in this case, the upper mold block 130 may be positioned at an angle to the horizontal plane and contact the upper surface of the intermediate mold block 120.

[0054] Similar to the lower slit 101 described above, the second spacer 133 can be placed between the intermediate mold block 120 and the upper mold block 130 to form a gap between them. Thus, an upper slit 102 is formed corresponding to the channel through which the second coating solution 60 flows. In this case, the vertical width (Y-axis direction, slit gap) of the upper slit 102 is determined by the second spacer 133. However, maintaining the slit gap is typically difficult because the mold blocks are prone to deformation and twisting.

[0055] Additionally, the second spacer 133, having a structure similar to the first spacer 113, has a second opening 133a, which is cut in one region and positioned in the remainder except for one side of the edge region of the facing surface of each of the intermediate mold block 120 and the upper mold block 130. Similarly, the circumferential direction is blocked except for the front side of the upper slit 102, and the upper outlet port 102a is formed only between the front ends of the intermediate mold block 120 and the upper mold block 130. The front end of the upper mold block 130 is defined as the upper mold lip 131; in other words, the upper outlet port 102a is formed by the gap between the intermediate mold lip 121 and the upper mold lip 131.

[0056] Additionally, the intermediate mold block 120 includes a second manifold 132 having a predetermined depth on its surface facing the upper mold block 130, and the second manifold 132 communicates with the upper slit 102. Although not shown in the figures, the second manifold 132 is connected by a supply pipe to a second coating solution supply chamber mounted externally, and is supplied with a second coating solution 60. When the second coating solution 60 is supplied from an external source along the supply pipe, and the second manifold 132 is completely filled with the second coating solution 60, the flow of the second coating solution 60 is guided along the upper slit 102 communicating with the second manifold 132 and exits from the upper outlet port 102a.

[0057] The upper slit 102 and the lower slit 101 form an angle, which can be approximately 30° to 60°. The upper slit 102 and the lower slit 101 can intersect at a point, and the upper outlet port 102a and the lower outlet port 101a can be located near this intersection. Therefore, the locations where the first coating solution 50 and the second coating solution 60 appear can be concentrated at approximately one point.

[0058] According to the multi-slit mold coating machine 100 with this configuration, a rotatable coating roller 200 is located in front of the multi-slit mold coating machine 100, and the coating roller 200 can rotate to move the substrate 300 to be coated, while making the first coating solution 50 and the second coating solution 60 continuously contact the surface of the substrate 300, so that the substrate 300 can be double-coated. Alternatively, by alternately supplying and stopping the first coating solution 50 and the second coating solution 60, a patterned coating can be intermittently formed on the substrate 300.

[0059] The multi-slit mold coating machine 100 extrudes and coats a coating solution onto the surface of a continuously moving substrate 300 through at least one of the lower slit 101 or the upper slit 102. The multi-slit mold coating machine 100 of the present invention includes bolts fastened at the contact surfaces between the lower mold block 110, the intermediate mold block 120 and the upper mold block 130. Figure 4 This is a cross-sectional view showing the bolt fastening between mold blocks in a multi-slit mold coating machine according to an embodiment of the present invention.

[0060] Reference Figure 4 Bolt 140 is fastened at the contact surface between intermediate mold block 120 and upper mold block 130. Bolt 140 is fastened such that the bolt head faces the lower outlet port 101a and the upper outlet port 102a. The angle α between the contact surface and the axis of bolt 140 is preferably within the range of 70 ± 10°. When the angle is outside the above range, the coating gap or slit gap changes. When the above range is met, alignment of the lower mold block 110, intermediate mold block 120, and upper mold block 130 toward the outlet port can be achieved.

[0061] Bolts (not shown) can be fastened at the contact surfaces between the lower mold block 110 and the intermediate mold block 120. A plurality of bolts 140 can be fastened along the width direction of the upper mold block 130, and a plurality of bolts 140 can be fastened along the length direction of the upper mold block 130.

[0062] It is important to fasten bolt 140 to the contact surface between the mold blocks so that the bolt head faces the outlet port. Figure 4 The example shown illustrates that the contact surfaces between the upper mold block 130 and the intermediate mold block 120 are inclined relative to the horizontal plane, and the bolt 140 is tightened to the contact surfaces at an angle of 70 ± 10°, such that the bolt head faces the upper outlet port 102a and the lower outlet port 101a. To illustrate the remarkable benefits of tightening the bolt 140 at an angle, a comparison is made with tightening the bolt at a non-angled position. Figure 5 It shows a cross-sectional view of a bolt being tightened such that the bolt head does not face the outlet port, contrary to the present invention. Figure 6 It shows Figure 5 Section A in the middle, and depicted with Figure 5 The direction of the force applied to the mold block by the bolt tightening angle.

[0063] Reference Figure 5 Bolt 160 is fastened perpendicularly to the horizontal plane at the contact surface between the intermediate mold block 120 and the upper mold block 130. As a result, as shown in the figure, bolt 160 forms an angle of 105° with the inclined contact surface.

[0064] Reference Figure 6 Due to the tilt angle of the intermediate mold block 120, the tightening force F of the bolt 160 is... f (Axial tension) is divided into a force F perpendicular to the contact surface and a force F parallel to the contact surface. 滑动 (F slip And due to the force F parallel to the contact surface slip Slippage will occur. When the force applied during fastening moves between the lower mold block 110, the intermediate mold block 120 and the upper mold block 130, this movement affects the coating gap, i.e. the distance between the upper exit port 101a and the lower exit port 102a and the substrate 300, resulting in uneven coating.

[0065] Therefore, the present invention tightens the bolt 140 at an angle such that the bolt head is tilted toward the outlet port, as shown. Figure 4As shown. When the bolt 140 is tightened according to the present invention, the direction of the tightening force acts without causing deformation of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130. For example, although the force of tightening the bolt 140 is divided into a force perpendicular to the contact surface and a force parallel to the contact surface, the parallel force acts in the opposite direction to the direction in which the upper mold block 130 may slide due to its weight. Therefore, the key point is that the lower mold block 110, the intermediate mold block 120, and the upper mold block 130 are prevented from deforming because the bolt 140 is tightened to apply a tightening torque rather than simply a fixing force. Therefore, when the multi-slit mold coating machine 100 is installed by assembling the lower mold block 110, the intermediate mold block 120, and the upper mold block 130, the variation in the coating gap can be reduced. Therefore, according to the present invention, the deformation of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130 can be minimized and lateral filling uniformity can be ensured, thereby improving the coating quality. The slit gap is defined by the first spacer 113 and the second spacer 133. However, conventionally, it is difficult to maintain the slit gap because the mold blocks are prone to deformation and twisting. Since the slit gap is an empty space, it is largely affected by the mold blocks that form the empty space. Therefore, the fastening of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130 with empty spaces according to the invention is significantly different from simply fastening the contact surfaces of the upper and lower structures that are simply in contact with each other. According to the invention, since the bolts 140 are fastened while preventing deformation of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130, changes in the empty space (i.e., the slit gap) are significantly and effectively prevented.

[0066] Although this embodiment describes pattern coating with two layers of coating solution or by supplying the coating solution alternately for illustrative purposes, it is clear that the invention can be applied to a combination of two types of coating solutions in the middle of a slit or to coating three or more layers simultaneously using three or more slits, rather than distributing them through individual slits. Obviously, three or more slits require four or more mold blocks.

[0067] Then, refer to Figure 7 Another embodiment of the invention is described below. The same reference numerals as in the above embodiments denote the same elements, and repeated descriptions of the same elements are omitted. The following description will be based on the differences from the above embodiments.

[0068] In the above embodiment, since it is an intermediate mold block 120, it is not possible to variably adjust the relative positions of the upper outlet port 102a and the lower outlet port 101a. However, according to another embodiment of the present invention, the relative positions of the upper outlet port 102a and the lower outlet port 101a can be easily adjusted.

[0069] Therefore, according to another embodiment of the present invention, a multi-slit mold coating machine 100' includes an intermediate mold block 120, which includes a first intermediate mold block 122 and a second intermediate mold block 124. The first intermediate mold block 122 and the second intermediate mold block 124 are in surface contact with each other at an upper position and a lower position, and are slidably disposed along the contact surface for relative movement. Furthermore, the first intermediate mold block 122 and the lower mold block 110 are fixed and coupled to each other by bolts, and the second intermediate mold block 124 and the upper mold block 130 are fixed and coupled to each other by bolts. Therefore, the first intermediate mold block 122 and the lower mold block 110 can move together, and the second intermediate mold block 124 and the upper mold block 130 can move together.

[0070] The multi-slit die coating machine 100' may include two outlet ports 101a and 102a, which are horizontally spaced apart from each other and positioned at a front and rear position as needed. That is, the relative movement of the lower die block 110 and the upper die block 130 can be achieved using a separate device for adjusting the shape of the multi-slit die coating machine 100' or through manual operation by the operator.

[0071] For example, by moving the upper mold block 130 a predetermined distance along the sliding surface in a forward or backward direction opposite to the direction in which the first coating solution 50 and the second coating solution 60 appear, while keeping the lower mold block 110 unchanged, a step D can be formed between the lower outlet port 101a and the upper outlet port 102a. Here, the sliding surface refers to the facing surfaces of the first intermediate mold block 122 and the second intermediate mold block 124.

[0072] The step width D can be determined in the range of approximately several hundred micrometers to several millimeters, and can be determined based on the properties and viscosity of the first coating solution 50 and the second coating solution 60 formed on the substrate 300, or the desired thickness of each layer on the substrate 300. For example, the step width D can increase as the thickness of the coating to be formed on the substrate 300 increases.

[0073] Furthermore, as described above, since the lower outlet port 101a and the upper outlet port 102a are spaced apart from each other in the horizontal direction, the second coating solution 60 flowing out from the upper outlet port 102a cannot enter the lower outlet port 101a, or the first coating solution 50 flowing out from the lower outlet port 101a cannot enter the upper outlet port 102a.

[0074] In other words, the coating solution discharged through the lower outlet port 101a or the upper outlet port 102a is blocked by a surface with a step between the lower outlet port 101a and the upper outlet port 102a, so the coating solution cannot enter the other outlet port, thus allowing the multilayer active material coating process to be carried out more smoothly.

[0075] When it is necessary to change the relative position between the lower outlet port 101a and the upper outlet port 102a, the multi-slit mold coating machine 100' according to another embodiment of the present invention can be easily adjusted by the sliding movement of the lower mold block 110 and / or the upper mold block 130, and there is no need to disassemble and reassemble each lower mold block 110, intermediate mold block 120 and upper mold block 130, thereby significantly improving processability.

[0076] As described above, according to another aspect of the invention, the positions of the upper and lower exit ports can be easily adjusted by the relative movement of the upper and lower mold blocks according to the coating process conditions, thereby improving the processability of multi-slit coating.

[0077] According to the present invention, the structural vulnerability of the mold block to deformation or twisting can be reduced, thereby uniformly forming a coating, particularly an electrode active material layer, with the desired thickness. Furthermore, two types of electrode active material slurries can be coated simultaneously, achieving high performance and high productivity. Deformation during mold block clamping can be prevented, ensuring the processability and reproducibility of the coating. When the multi-slit mold coating machine of the present invention is used to coat electrode active material slurries onto current collectors in the manufacture of electrodes for secondary batteries, uniform coating can be achieved under high-speed or large-scale coating conditions.

[0078] The following will describe examples demonstrating the effectiveness of the invention through actual experiments. Preparation of... Figure 5 Comparative examples of fastening and having Figure 4 An example of fastening is provided to check the alignment of the die blocks on the left and right sides in the width direction of the multi-slit die coater.

[0079] Figure 8 These are photographic images of a comparative example contrary to the present invention, showing the alignment between mold blocks using bolts to fasten them so that the bolt heads do not face the outlet port. A side view of the multi-slit mold coating machine. Reference. Figure 8In the comparative example, the lower die block (lower plate) is positioned at the lowest point on the left side of the multi-slit die coater, but at the highest point on the right side. That is, the lower die block (lower plate), the intermediate die block (intermediate plate), and the upper die block (upper plate) are not aligned towards the exit port, and the die lips are not aligned in a straight line. Furthermore, the alignment on the left and right sides are different from each other. Therefore, it can be seen that when the bolts are tightened so that the bolt heads do not face the exit port, the coating gap varies in the width direction of the multi-slit die coater, resulting in a large filling deviation.

[0080] Figure 9 This is a photographic image illustrating the alignment between mold blocks according to the invention, where bolts are used to fasten the bolt heads towards the outlet port. A side view of the multi-slit mold coating machine.

[0081] Reference Figure 9 In this example, the lower mold block (lower plate), the middle mold block (middle plate), and the upper mold block (upper plate) are aligned with the exit ports on the left and right sides of the multi-slit mold coating machine, and the mold lips are aligned in a straight line. Therefore, it can be seen that, as proposed in this invention, when the bolt head faces the exit port, the coating gap does not change in the width direction of the multi-slit mold coating machine, and thus no filling deviation occurs.

[0082] At the same time, as referenced Figure 4 Preferably, the angle α between the contact surface and the axis of the bolt 140 is within the range of 70±10°. When the angle is outside the above range, the coating gap or slit gap changes.

[0083] When the electrode active material slurry is supplied, pressure is applied to the interior of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130, and these blocks can deform proportionally to the pressure and contact area of ​​the electrode active material slurry. Since the slit gap may deform significantly due to the structural features of the lower mold block 110, the intermediate mold block 120, and the upper mold block 130, the slit gap at the center is wider than the slit gaps at the two edges along the width direction of the multi-slit mold coating machine 100, due to the pressure when the electrode active material slurry is applied. Therefore, the electrode coating at the center is thicker than the electrode coating at the two edges. Simultaneously, when multiple bolts 140 are tightened along the width direction of the upper mold block 130, the change in slit gap is reversed due to the positional characteristics of the bolts 140; in other words, the center of the multi-slit mold coating machine 100 is narrower than the two edges. This invention proposes a bolt head facing the lower outlet port 101a and the upper outlet port 102a of a fastening bolt, taking into account the variation in slit gap due to the pressure of the electrode active material slurry and the variation in slit gap due to the bolt fastening position. However, when the angle α between the contact surface and the axis of the bolt 140 is too small, i.e., when the bolt 140 is tilted too much, it may cause... Figure 5 and 6 The sliding described herein. That is, during assembly, sliding may occur at the contact surfaces between the intermediate mold block 120 and the upper mold block 130, causing misalignment of the intermediate mold block 120 and the upper mold block 130 along the direction of the coating gap. For example, as... Figure 8 As shown, the mold lip may not be aligned in a straight line. With this in mind, the angle α between the contact surface and the axis of bolt 140 preferably has a predetermined range, and the present invention proposes a preferred angle range of 70 ± 10°.

[0084] In the experimental example, considering a bolt tightening angle of 70° and an electrode active material slurry pressure of 100 kPa, the difference between the slit gap at the center and the slit gap at the edge is 6 μm. During assembly, the alignment of the mold lip and mold block movement is ±8 μm. When the pressure of the electrode active material slurry is not considered, the difference between the slit gap at the center and the slit gap at the edge is -15 μm.

[0085] When the bolt tightening angle is 50°, the difference between the slit gap at the center and the slit gap at the edge increases significantly to -11 μm. During assembly, the alignment of the mold lip and the mold block movement increases significantly to ±30 μm. When the pressure of the electrode active material slurry is not considered, the difference between the slit gap at the center and the slit gap at the edge is -28 μm.

[0086] When considering a bolt tightening angle of 90° and an electrode active material slurry pressure of 100 kPa, the alignment of the mold lip and mold block movement during assembly is ±5 μm, indicating optimal alignment. When the electrode active material slurry pressure is not considered, the difference between the slit gap at the center and the slit gap at the edge is -5 μm, indicating optimal alignment. However, the difference between the slit gap at the center and the slit gap at the edge increases significantly to 14 μm.

[0087] When the standard setting for die lip alignment used for stabilizing the coating is 10 μm or less, a 50° bolt tightening angle does not meet the standard. Apart from the deformation of the electrode active material slurry, a 90° bolt tightening angle is good, but even taking into account the deformation of the electrode active material slurry when actually using a multi-slit die coater 100, tightening the bolt 140 at 70° ensures the best coating quality.

[0088] Figure 10 This is a cross-sectional view showing the bolt fastening between die blocks in a multi-slit die coating machine according to yet another embodiment of the present invention. The same reference numerals as in the above embodiment denote the same elements, and repeated descriptions of the same elements are omitted; the following description will be based on the differences from the above embodiment. Instead of... Figure 4 The bolt in the middle is 140. Figure 10 Bolt 170 is shown.

[0089] Reference Figure 10 Bolt 170 is fastened at the contact surface between the upper mold block 130 and the intermediate mold block 120. Bolt 170 is fastened such that the bolt head faces the downward outlet port 101a and the upper outlet port 102a. Multiple bolts 170 can be fastened along the width direction of the upper mold block 130, and multiple bolts 170 can be fastened along the length direction of the upper mold block 130.

[0090] Bolt 170 includes bolt head 172 and bolt leg 174. Bolt head 172 protrudes beyond upper mold block 130.

[0091] Bolt leg 174 includes a threaded portion 174a near the intermediate mold block 120 and a smooth portion 174b near the upper mold block 130. To accommodate bolt 150, the upper mold block 130 and the intermediate mold block 120 have bolt holes 175b and 175a aligned with each other.

[0092] Each lower mold block 110, intermediate mold block 120, and upper mold block 130 is prone to deformation due to its small thickness, and bolt tightening is susceptible to deformation due to the large forces involved, thus requiring careful handling. Tolerances in the holes used for bolt tightening can cause deformation in each of the lower mold block 110, intermediate mold block 120, and upper mold block 130. When impurities enter the tolerable holes, assembly imbalance occurs during bolt tightening, leading to deformation. Because a multi-slit die coating machine 100” is used during the application of the electrode active material slurry, impurities may enter the holes with a high probability or in large quantities, and once introduced, they are difficult to remove; therefore, preventing impurity entry is crucial.

[0093] In this embodiment, the bolt head 172 is not embedded in the upper mold block 130 and protrudes beyond it. Even if there are tolerances in the holes 175a and 175b used for bolt fastening, impurities can be prevented from entering the holes 175a and 175b because the bolt head 172 closes the hole 175b. Therefore, imbalance of the bolt fastening assembly caused by impurities introduced into the holes can be prevented, and deformation of each mold block can be avoided.

[0094] As described above, according to another aspect of the invention, impurities can be prevented from entering the holes 175a, 175b used for bolt fastening, and deformation of each mold block can be avoided. Meanwhile, the bolt head 172 protrudes beyond the upper mold block 130, and the bolt 170 is longer than the bolt 140 in order to fasten the contact surface between the upper mold block 130 and the intermediate mold block 120 by means of the bolt 170. In this case, when the thread is formed throughout the bolt leg 174, a large torque is applied during bolt fastening, and a long time is required for fastening. Therefore, it may be desirable to form threads in the area requiring fastening, while not forming threads in the remaining area. Therefore, the bolt leg 174 may include a threaded portion 174a near the intermediate mold block 120 and a smooth portion 174b near the upper mold block 130. Although the invention has been described with respect to a limited number of embodiments and drawings, the invention is not limited thereto, and it will be apparent to those skilled in the art that various changes and modifications can be made to the technical aspects of the invention and to the appended claims and their equivalents.

Claims

1. A multi-slit mold coating machine comprising a lower slit and an upper slit, wherein a coating solution is extruded and coated onto the surface of a continuously moving substrate through at least one of the lower slit or the upper slit, the multi-slit mold coating machine comprising: Lower mold block; An intermediate mold block is located on the lower mold block, such that the lower slit is formed between the intermediate mold block and the lower mold block; as well as An upper mold block is located on the intermediate mold block, such that the upper slit is formed between the upper mold block and the intermediate mold block. The lower mold block, the intermediate mold block, and the upper mold block each have a lower mold lip, an intermediate mold lip, and an upper mold lip. The lower mold lip, the intermediate mold lip, and the upper mold lip respectively form the front ends of the lower mold block, the intermediate mold block, and the upper mold block. A lower outlet port is formed between the lower mold lip and the intermediate mold lip and communicates with the lower slit. An upper outlet port is formed between the intermediate mold lip and the upper mold lip and communicates with the upper slit. The multi-slit mold coating machine includes bolts fastened at the contact surfaces between the intermediate mold block and the upper mold block, the bolts being angled such that the bolt heads face the upper outlet port and the lower outlet port. The angle between the contact surface and the axis of the bolt is within the range of 70±10°.

2. The multi-slit mold coating machine according to claim 1, wherein, The multi-slit mold coating machine includes bolts fastened at the contact surface between the intermediate mold block and the lower mold block.

3. The multi-slit mold coating machine according to claim 1, wherein the contact surface between the upper mold block and the intermediate mold block is inclined.

4. The multi-slit die coating machine according to claim 1, wherein the intermediate die block includes a first intermediate die block and a second intermediate die block whose surfaces are in contact with each other at an upper position and a lower position, the first intermediate die block and the second intermediate die block being slidably disposed along the contact surface for relative movement, and The first intermediate mold block is fixed and coupled to the lower mold block, and the second intermediate mold block is fixed and coupled to the upper mold block.

5. The multi-slit mold coating machine according to claim 1, wherein a predetermined step is formed between the lower outlet port and the upper outlet port.

6. The multi-slit mold coating machine according to claim 1 further includes: A first spacer is placed between the lower mold block and the intermediate mold block to adjust the width of the lower slit. A second spacer is placed between the intermediate mold block and the upper mold block to adjust the width of the upper slit.

7. The multi-slit mold coating machine according to claim 1, wherein the lower mold block includes a first manifold for receiving a first coating solution, the first manifold being in communication with the lower slit, and the intermediate mold block includes a second manifold for receiving a second coating solution, the second manifold being in communication with the upper slit.

8. The multi-slit mold coating machine according to claim 1, wherein the lower slit and the upper slit form an angle of 30° to 60°.

9. The multi-slit mold coating machine according to claim 1, wherein the bolt head of the bolt protrudes beyond the upper mold block.

10. The multi-slit mold coating machine according to claim 9, wherein the bolt leg of the bolt includes a threaded portion near the intermediate mold block and a smooth portion near the upper mold block, and the upper mold block and the intermediate mold block have bolt holes aligned with each other to receive the bolt.

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