Spacer shim, slot die coater and coating method using them

Abstract

The present invention discloses a spacer shim, a slot die coater including the same, and a coating method using the same. The spacer shim includes a plate-shaped shim body having a predetermined width, length, and thickness, and a flow path portion formed of a groove recessed in the thickness direction on one surface of the shim body. The flow path portion may include an inlet trench through which a coating liquid flows in the thickness direction, first and second outlet trenches spaced apart in the width direction and independently outlet the coating liquid in the longitudinal direction, first and second bending trenches branching from one and the other sides of the inlet trench and extending along the width and longitudinal directions, and first and second connection trenches extending in the longitudinal direction from the first and second bending trenches, respectively, and communicating with the first and second outlet trenches.

Description

[Technical Field]

[0001] The present invention relates to a spacer shim, a slot die coater, and a coating method using the same, and more particularly to a spacer shim having an improved flow path structure for improving coating quality, a slot die coater including the same, and a coating method using the slot die coater.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0183772, filed on December 23, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof. [Background technology]

[0003] Slot die coaters are widely used to coat active or insulating materials on battery electrode plates. They include a spacer shim interposed between two slot die blocks.

[0004] The spacer forms a flow path within the slot die coater, the flow path including an inlet flow path through which the coating liquid is introduced from the outside, a discharge flow path through which the coating liquid is sprayed to the outside, and a connection flow path that connects the inlet flow path and the discharge flow path.

[0005] The structural design of the spacer shim flow path affects the coating quality. If the flow path design is not optimized, not only will the coating quality be reduced, but foreign matter may flow deep into the slot die coater during the process of cleaning the lip. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in light of the background of the prior art described above, and has an object to provide a spacer shim having an improved flow path structure to improve coating quality.

[0007] Another object of the present invention is to provide a slot die coater that includes an improved spacer shim.

[0008] It is yet another object of the present invention to provide a coating method using a slot die coater that includes an improved spacer shim. [Means for solving the problem]

[0009] To achieve the above object, the spacer shim according to the present invention may include a plate-shaped shim body having a predetermined width, length, and thickness, and a flow path portion consisting of a groove recessed in the thickness direction on one surface of the shim body.

[0010] The flow path portion may include an inflow trench through which the coating liquid flows in the thickness direction, first and second discharge trenches spaced apart in the width direction and independently discharging the coating liquid in the longitudinal direction, first and second bending trenches branching from one and the other sides of the inflow trench and extending along the width direction and the longitudinal direction, respectively, and first and second connection trenches extending from the first and second bending trenches in the longitudinal direction, respectively, and communicating with the first and second discharge trenches.

[0011] The first discharge trench and the first connection trench may be spaced apart from each other in the width direction and may not overlap each other in the longitudinal direction, and the second discharge trench and the second connection trench may be spaced apart from each other in the width direction and may not overlap each other in the longitudinal direction.

[0012] When an average flow path width of the first bending trench and an average flow path width of the second bending trench are defined as a first flow path width, an average flow path width of the first connection trench and an average flow path width of the second connection trench are defined as a second flow path width, and an average flow path width of the first discharge trench and an average flow path width of the second discharge trench are defined as a third flow path width, the first flow path width may be larger than the second flow path width, and the second flow path width may be larger than the third flow path width.

[0013] When the maximum separation distance in the width direction between the first bending trench and the second bending trench is defined as a first separation distance, the maximum separation distance in the width direction between the first connection trench and the second connection trench is defined as a second separation distance, and the maximum separation distance in the width direction between the first discharge trench and the second discharge trench is defined as a third separation distance, the first separation distance may be smaller than the second separation distance, and the second separation distance may be smaller than the third separation distance.

[0014] The flow path portion may further include a bridge trench, one end of the bridge trench may be interposed between the first discharge trench and the first connection trench, and the other end of the bridge trench may be interposed between the second discharge trench and the second connection trench.

[0015] The bridge trench may have a channel width greater than the channel widths of the first discharge trench and the second discharge trench.

[0016] The depth of the bridge trench may be substantially the same as the depth of the first discharge trench and the depth of the second discharge trench.

[0017] The flow path portion may further include a bridge trench, one end of the bridge trench may communicate with the first connection trench, and the other end of the bridge trench may communicate with the second connection trench.

[0018] The channel width of the bridge trench may be smaller than the channel width of the first connection trench and the channel width of the second connection trench.

[0019] The bridge trench may communicate with the first connection trench and the second connection trench at the same depth.

[0020] The bridge trench may intersect the first discharge trench and the second discharge trench substantially perpendicularly, and the channel width at the intersection may gradually decrease toward the discharge trench.

[0021] The flow passage at the intersection may have a structure in which an inner right-angled corner and an outer rounded corner face each other.

[0022] The first connection trench and the second connection trench may each include a first section having a first average depth along the longitudinal direction of the shim body, a second section having a second average depth, and a third section having a third average depth, wherein the first average depth is greater than the second average depth and the second average depth is greater than the third average depth.

[0023] The first section and the third section may each have a trench depth that is substantially the same along the flow direction of the coating liquid, and the second section may have a trench depth that gradually decreases along the flow direction of the coating liquid.

[0024] The depth of the trench in the third section may be substantially the same as the depth of the first discharge trench and the second discharge trench.

[0025] The trench constituting the flow path portion may have a rounded bottom when viewed from a cross section perpendicular to the direction in which the coating liquid flows.

[0026] The spacer shim according to the present invention may include at least one fastening hole passing through the shim body so as not to overlap with the flow path portion.

[0027] The spacer shim according to the present invention may include a coating layer formed on the exposed surface of the flow path portion in a thickness direction of the shim body.

[0028] The coating layer may include polytetrafluoroethylene.

[0029]

[0013] In addition, a slot die coater for achieving the above object may include at least one spacer shim as described above; a first slot die block coupled to one side of the shim body so as to face the exposed surface of the flow path portion in a thickness direction of the shim body; a second slot die block coupled to the other side of the shim body so as to face the first slot die block; and a coating liquid supply unit communicating with the inlet trench of the spacer shim.

[0030] The slot die coater according to the present invention may include at least one pump that independently supplies coating liquid from a coating liquid supply portion that communicates with the inlet trench of each spacer shim.

[0031] A coating method for achieving the above object may include a first step of preparing a substrate having a pair of short sides and a pair of long sides extending between the pair of short sides; a step of forming a plurality of first coating layers at predetermined intervals on one surface of the substrate along the long side direction, so that strip-shaped uncoated portions extending along the long side direction are formed between first coating layers adjacent in the short side direction; a step of preparing the slot die coater; and a step of forming, using the slot die coater, second coating layers along the long side direction, each covering the boundary between each first coating layer and an adjacent uncoated portion by a predetermined width.

[0032] The second coating layer may be formed as a pair simultaneously at the boundary between the pair of first coating layers facing the non-coating portion and the non-coating portion.

[0033] In the coating method according to the present invention, the substrate may be a metal foil current collector, the first coating layer may be an active material coating layer, and the second coating layer may be an insulating coating layer. [Effects of the Invention]

[0034] According to one aspect of the present invention, the structure of the flow path portion of the spacer shim is improved, thereby improving the coating quality, particularly the uniformity of the coating width.

[0035] According to another aspect of the present invention, it is possible to prevent foreign matter from flowing into the interior of the slot die coater during the process of cleaning the lip of the slot die coater.

[0036] According to yet another aspect of the present invention, a substrate having a plurality of strip-shaped first coating layers formed at regular intervals with uncoated portions sandwiched therebetween is traveled, and a second coating layer is formed at the boundary between each first coating layer and the uncoated portion, whereby the width of the second coating layer can be maintained uniform in a direction perpendicular to the travel direction. [Brief explanation of the drawings]

[0037] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention, so the present invention should not be interpreted as being limited to the matters described in the drawings. [Figure 1] FIG. 2 is a plan view of a spacer shim according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA' in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line BB′ in FIG. [Figure 4] 2 is a partially enlarged view showing the portion circled by the dotted line on the right side of FIG. 1. FIG. [Figure 5] FIG. 10 is a plan view showing the structure of a spacer shim according to another embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing the configuration of a slot die coater according to an embodiment of the present invention. [Figure 7] FIG. 1 is a plan view of a slot die coater according to an embodiment of the present invention. [Figure 8]1 is a process diagram conceptually illustrating a coating method according to an embodiment of the present invention. [Figure 9] 10 is a photograph of a current collector immediately after forming a positive electrode active material layer and an insulating coating layer on one side of the current collector made of aluminum foil using a slot die coater including a spacer shim according to a comparative example of the present invention. [Figure 10] 1 is a photograph of a current collector immediately after forming a positive electrode active material layer and an insulating coating layer on the current collector made of aluminum foil using a slot die coater including a spacer shim according to an embodiment of the present invention. [Figure 11] 1 is a graph showing the results of measuring the average thickness of the insulating coating layer for each uncoated line when seven lines of positive electrode active material layers with a width of 125.5 mm were coated at 10 mm intervals on one surface of an aluminum current collector, and then a total of six pairs of insulating coating layers were formed on a total of six uncoated lines using the slot die coater used in the comparative examples and examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts corresponding to the technical concept of the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of terms in order to best explain the invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical concept of the present invention, and therefore, various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0039] Terms such as "first" and "second" are used to describe various components, but these terms do not limit the components. These terms are used to distinguish only one component from another, and unless otherwise specified, the first component may be the second component.

[0040] Furthermore, throughout the specification, unless otherwise specified, each element may be singular or plural.

[0041] Hereinafter, when an arbitrary structure is placed "on top (or bottom)" of a component or "above (or below)" a component, it may mean that the arbitrary structure is placed directly on the top (or bottom) surface of the component, but also that another structure may be interposed between the component and the arbitrary structure placed above (or below) the component.

[0042] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" by other components.

[0043] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "include" are not necessarily interpreted as including multiple components or multiple steps described in the specification, and some components or steps may not be included, or additional components or steps may be further included.

[0044] Throughout the specification, unless otherwise specified, "A and / or B" means "A," "B," or "A and B," and "C to D" means at least C and at most D, unless otherwise specified.

[0045] FIG. 1 is a plan view of a spacer shim according to one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A' in FIG. 1, FIG. 3 is a cross-sectional view taken along line B-B' in FIG. 1, and FIG. 4 is an enlarged partial view showing the dotted circle portion on the right side of FIG. 1.

[0046] Referring to Figures 1 to 4, a spacer shim 10 according to an embodiment of the present invention may include a plate-shaped shim body 11 having a predetermined width, length, and thickness, and a flow path portion 12 consisting of a groove recessed in the thickness direction from one surface of the shim body 11.

[0047] For ease of explanation, the drawings are shown in a three-dimensional coordinate system, where the X axis is the width direction of the shim body 11, the Y axis is the length direction of the shim body 11, and the Z axis is the thickness direction of the shim body 11.

[0048] In Figure 1, the shading of the flow path section 12 indicates the difference in depth in the thickness direction Z. The darker the shading, the deeper the depth in the thickness direction Z. Furthermore, areas with the same shading may have substantially the same depth in the thickness direction Z. The depth of the flow path section 12 may be the maximum depth at the measurement position.

[0049] The flow path portion 12 may have a bilaterally symmetrical structure with respect to the longitudinal direction (Y-axis direction). The flow path portion 12 may have a trench structure recessed along the thickness direction (Z-axis direction) from one surface of the shim body 11. The trench may be a kind of groove.

[0050] The flow path portion 12 may include an inlet trench 12a into which the coating liquid flows in a thickness direction (Z-axis direction), first discharge trenches 12b1 and 12b2 spaced apart in a width direction (X-axis direction) and independently discharging the coating liquid in a longitudinal direction (Y-axis direction), a first bending trench 12c1 and a second bending trench 12c2 branching from one side and the other of the inlet trench 12a, respectively, and extending along the width direction (X-axis direction) and the longitudinal direction (Y-axis direction), and a first connection trench 12d1 and a second connection trench 12d2 extending from the first bending trench 12c1 and the second bending trench 12c2, respectively, in the longitudinal direction (Y-axis direction) and directly or indirectly connected to the first discharge trench 12b1 and the second discharge trench 12b2.

[0051] When the average flow path width of the first bending trench 12c1 and the average flow path width of the second bending trench 12c2 are defined as a first flow path width, the average flow path width of the first connection trench 12d1 and the average flow path width of the second connection trench 12d2 are defined as a second flow path width, and the average flow path width of the first discharge trench 12b1 and the average flow path width of the second discharge trench 12b2 are defined as a third flow path width, the first flow path width may be larger than the second flow path width, and the second flow path width may be larger than the third flow path width.

[0052] The average flow path width refers to the average length of line segments located within the trench when lines are drawn at multiple points in the trench section in a direction perpendicular to the direction of coating liquid flow on the same plane as the surface of the shim body 11. The multiple points may be selected, for example, every 0.5 mm. In the drawings, W1, W2, and W3 indicate the lengths of line segments drawn at specific points in each trench section.

[0053] In a specific example, the first channel width may be 4 mm±0.5 mm, the second channel width may be 2 mm±0.5 mm, and the third channel width may be 1.3 mm±0.5 mm.

[0054] When the maximum separation distance d1 in the width direction between the first bending trench 12c1 and the second bending trench 12c2 is defined as a first separation distance, the maximum separation distance d2 in the width direction between the first connection trench 12d1 and the second connection trench 12d2 is defined as a second separation distance, and the maximum separation distance d3 in the width direction between the first discharge trench 12b1 and the second discharge trench 12b2 is defined as a third separation distance, the first separation distance d1 may be smaller than the second separation distance d2, and the second separation distance d2 may be smaller than the third separation distance d3.

[0055] In a specific example, the first separation distance may be 10 mm±2 mm, the second separation distance may be 14 mm±1.5 mm, and the third separation distance may be 17 mm±1.0 mm.

[0056] The flow path portion 12 may further include a bridge trench 12e.

[0057] One end of the bridge trench 12e in the width direction (X-axis direction) may be interposed between the first discharge trench 12b1 and the first connection trench 12d1, and the other end of the bridge trench 12e in the width direction (X-axis direction) may be interposed between the second discharge trench 12b2 and the second connection trench 12d2.

[0058] Therefore, the first discharge trench 12b1 and the first connection trench 12d1 may be indirectly connected to each other through one end of the bridge trench 12e, and the second discharge trench 12b2 and the second connection trench 12d2 may be indirectly connected to each other through the other end of the bridge trench 12e.

[0059] The depth of the bridge trench 12e may be substantially the same as the depth of the first discharge trench 12b1 and the depth of the second discharge trench 12b2.

[0060] The channel width of the bridge trench 12e may be relatively larger than the channel width of the first discharge trench 12b1 and the channel width of the second discharge trench 12b2.

[0061] The channel width of the bridge trench 12e may be relatively smaller than the channel width of the first connection trench 12d1 and the channel width of the second connection trench 12d2.

[0062] The design of the flow path width and depth of the bridge trench 12e as described above can improve coating quality by increasing the flow path pressure of the first discharge trench 12b1 and the second discharge trench 12b2 to substantially the same level.

[0063] The bridge trench 12e may intersect the first discharge trench 12b1 and the second discharge trench 12b2 substantially perpendicularly.

[0064] Referring to FIG. 4, the channel width of the perpendicular intersection (dotted circle) may gradually decrease toward the first discharge trench 12b1 and the second discharge trench 12b2.

[0065] In addition, the flow path at the perpendicular intersection (dotted circle) may have a structure in which an inner right-angled corner 20 formed at a right angle and an outer rounded corner 21 formed in an arc shape face each other.

[0066] 2, the first connection trench 12d1 and the second connection trench 12d2 each include a first section (1) having a first average depth along the flow direction of the coating liquid, a second section (2) having a second average depth, and a third section (3) having a third average depth, and the first average depth may be greater than the second average depth, and the second average depth may be greater than the third average depth. Here, it should be noted that "(1)", "(2)", and "(3)" in the first section (1), second section (2), and third section (3) correspond to the circled numbers 1, 2, and 3 shown in FIG. 2, respectively.

[0067] The first section (1) and the third section (3) each have a trench depth that is substantially the same along the flow direction of the coating liquid, and the second section (2) may have a trench depth that gradually decreases along the flow direction of the coating liquid.

[0068] The depth of the trench may be measured based on the lowest point of the flow path (for example, the center point of the bottom in the cross-sectional view of the trench shown in FIG. 3) where the depth is smallest, based on each measurement point of the flow path.

[0069] The depth of the trench in the third section (3) may be substantially the same as the depth of the first discharge trench 12b1 and the second discharge trench 12b2.

[0070] The depth of the trench in the third section (3) may be substantially the same as the depth of the bridge trench 12e.

[0071] The depth of the first bending trench 12c1 and the second bending trench 12c2 may be substantially the same as the depth of the first section (1).

[0072] In one embodiment, the ratio of the depth of the third section (3) to the depth of the first section (1) may be 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less.

[0073] In one embodiment, the ratio of the depth of the first section (1) to the thickness of the shim body 11 may be 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less.

[0074] In one embodiment, the gradient ΔZ / ΔY of the second section (2) may be 0.07 mm or less, 0.05 mm or less, 0.04 mm or less, 0.03 mm or less, or 0.02 mm or less, where ΔZ is the change in the Z-axis direction and ΔY is the change in the Y-axis direction.

[0075] In a specific example, the thickness of the shim body 11 may be 1.5 mm, the depth of the first section (1) may be 1.0 mm, the depth of the third section (3) may be 0.5 mm, the length of the second section (2) in the Y-axis direction may be 10 mm, and the slope (ΔZ / ΔY) of the second section (2) may be 0.05.

[0076] 3, the trench constituting the flow path portion 12 may have a rounded bottom when viewed from a cross section E perpendicular to the direction in which the coating liquid flows. When the trench has a rounded bottom, the coating liquid can be prevented from stagnating in areas where the flow of the coating liquid is weak, thereby improving the coating quality.

[0077] The spacer shim 10 gradually or stepwise reduces the depth of the flow path along the direction of the coating liquid flow, thereby increasing the flow path pressure toward the first discharge trench 12b1 and the second discharge trench 12b2. Furthermore, the bridge trench 12e equalizes the flow path pressure in the first discharge trench 12b1 and the second discharge trench 12b2. Therefore, the spacer shim 10 can improve the uniformity of coating quality. In particular, it can minimize the deviation in coating width between the coating layer formed by the coating liquid discharged from the first discharge trench 12b1 and the coating layer formed by the coating liquid discharged from the second discharge trench 12b2.

[0078] Referring to FIG. 4, the bridge trench 12e perpendicularly intersects with the first connection trench 12d1 and the first discharge trench 12b1.

[0079] At the perpendicular intersection (dotted circle), the flow path width gradually decreases along the flow direction of the coating liquid (direction of the arrow).

[0080] The perpendicular intersection (dotted circle) may have a structure in which an inner right-angled corner 20 and an outer rounded corner 21 face each other when the spacer shim 10 is viewed from the Z-axis direction.

[0081] When the spacer shim 10 is viewed from the Z-axis direction, the round corner 21 can include a curved portion 21a having a radius of curvature and a straight portion 21b smoothly connecting to the curved portion 21a.

[0082] The angle θ formed between the linear portion 21b and the outer line of the first connection trench 12d1 may be 110° to 130°.

[0083] The first discharge trench 12b1 is spaced outward from the first connection trench 12d1 in the width direction (X-axis direction) by the vertical intersection (dotted circle). Therefore, the coating liquid passing through the first connection trench 12d1 does not immediately move to the first discharge trench 12b1, but moves to the first discharge trench 12b1 via the vertical intersection (dotted circle). This coating liquid flow mechanism prevents degradation of coating quality due to pulsation generated by the pump motor that supplies the coating liquid. Furthermore, because the first discharge trench 12b1 is not directly connected to the first connection trench 12d1, it prevents foreign matter from penetrating deep into the spacer shim 10 during the process of cleaning the lip of a slot die coater including the spacer shim 10. Preventing the penetration of foreign matter also prevents degradation of coating quality due to foreign matter.

[0084] The structure shown in FIG. 4 can be substantially equally applied to the portion where the bridge trench 12e intersects with the second connection trench 12d2 and the second discharge trench 12b2 due to the bilateral symmetrical structure of the spacer shim 10.

[0085] Referring again to FIG. 1, the spacer shim 10 may include at least one fastening hole 22 passing through the shim body 11 so as not to overlap with the flow path portion 12 .

[0086] The fastening holes 22 can be used when the spacer shim 10 is mounted on a slot die coater. The fastening holes 22 can have threads on their inner circumferential surfaces for fastening bolts.

[0087] At least one fastening hole 22 may be provided in an inner region of the shim body 11 surrounded by the first bending trench 12c1, the first connection trench 12d1, the bridge trench 12e, the second connection trench 12d2, the first bending trench 12c2, and the inflow trench 12a.

[0088] At least two or more fastening holes 22 may be provided in the area of ​​the shim body 11 excluding the inner area.

[0089] A coating layer having a low surface friction coefficient may be provided on a part or the entire exposed surface of the flow path portion 12 to reduce contamination. In one example, the coating layer may include polytetrafluoroethylene (PTFE). The coating layer may be formed on the exposed surface of the shim body 11.

[0090] FIG. 5 is a plan view showing the structure of a spacer shim 10' according to another embodiment of the present invention.

[0091] 5, the spacer shim 10' may include a bridge trench 12e' having another structure. One end of the bridge trench 12e' may connect to a first connection trench 12d1, and the other end of the bridge trench 12e may connect to a second connection trench 12d2. The connection point of the bridge trench 12e' is preferably near the first discharge trench 12b1 and the second discharge trench 12b2.

[0092] The depth of the bridge trench 12e may be substantially the same as the depth of the first connection trench 12d1 and the second connection trench 12d2 at the point where the bridge trench 12e is connected to the first connection trench 12d1 and the second connection trench 12d2.

[0093] In the spacer shim 10', the first connection trench 12d1 and the first discharge trench 12b1 may be directly connected to each other, and the second connection trench 12d2 and the second discharge trench 12b2 may be directly connected to each other.

[0094] The first connection trench 12d1 and the first discharge trench 12b1 are not aligned on the same line along the longitudinal direction (Y-axis direction), and the second connection trench 12d2 and the second discharge trench 12b2 are not aligned on the same line along the longitudinal direction (Y-axis direction). This structure is substantially the same as the spacer shim 10 described above.

[0095] The connection portion between the first connection trench 12d1 and the first discharge trench 12b1 and the connection portion between the second connection trench 12d2 and the second discharge trench 12b2 may have a structure in which an inner right-angled corner 20' and an outer rounded corner 21' face each other. The inner right-angled corner 20' may have a chamfered corner. The shape of the outer rounded corner 21' may be substantially the same as the corresponding structure shown in FIG. 4.

[0096] The flow path width of the bridge trench 12e' may be relatively smaller than the flow path widths of the first connection trench 12d1 and the second connection trench 12d2.

[0097] The above-described design of the flow path width and depth of the bridge trench 12e' increases the flow path pressure of the first discharge trench 12b1 and the second discharge trench 12b2 to substantially the same level, thereby improving coating quality.

[0098] Spacer shims 10, 10' according to embodiments of the present invention may be included in a slot die coater.

[0099] FIG. 6 is a cross-sectional view showing the configuration of a slot die coater 30 according to an embodiment of the present invention, and FIG. 7 is a plan view of the slot die coater 30 according to an embodiment of the present invention.

[0100] 6, the slot die coater 30 may include the above-described spacer shim 10. The spacer shim 10 may be replaced with a spacer shim 10' according to another embodiment.

[0101] In addition, the slot die coater 30 may include a first slot die block 31 coupled to one side of the shim body 11 of the spacer shim 10 so as to face the exposed surface of the flow path portion 12 of the spacer shim 10, and a second slot die block 32 coupled to the other side of the shim body 11 so as to face the first slot die block 31.

[0102] The first slot die block 31 may include a coating liquid supply 33 in communication with the inlet trench 12 a of the spacer shim 10 .

[0103] The coating liquid supply unit 33 may include a coating liquid introduction chamber 33a recessed in the thickness direction of the first slot die block 31, a coating liquid inlet hole 33b communicating with the coating liquid introduction chamber 33a and drilled in the thickness direction of the first slot die block 31, and a coating liquid supply pipe 33c having one end connected to the coating liquid inlet hole 33b and the other end connected to a pump (not shown).

[0104] The first slot die block 31 and the second slot die block 32 may be coupled together by at least one bolt fastening structure 34 .

[0105] The bolt fastening structure 34 may include a bolt fastening hole 34a formed in the first slot die block 31 and having a thread formed on the inner surface, a bolt guide hole 34b formed in the second slot die block 32 for guiding the insertion of a bolt from the outside, and a bolt 34c inserted through the bolt guide hole 34b and coupled to the bolt fastening hole 34a.

[0106] The detailed structure of the bolt fastening structure 34 is not limited to the embodiment. The bolt fastening hole 34a may be formed in the second slot die block 32, and the bolt guide hole 34b may be formed in the first slot die block 31. In addition, various bolt fastening structures known in the art may be adopted.

[0107] The first slot die block 31 and the second slot die block 32 may be connected to each other by other mechanical methods such as welding in addition to bolt fastening.

[0108] 7, the slot die coater 30 may include a plurality of spacer shims 10. The plurality of spacer shims 10 may be arranged at predetermined intervals along the X-axis direction.

[0109] The slot die coater 30 can simultaneously form coating layers on the surface of a substrate (reference numeral 35 in FIG. 6) moving in the Y-axis direction along the direction of movement of the substrate 35, the number of which is twice the number of spacer shims 10. In one example, when the number of spacer shims 10 is seven, 14 coating layers can be simultaneously formed on the surface of the substrate 35.

[0110] 6, the substrate 35 is transported in close contact with a roller 36, and the slot die coater 30 can continuously form a coating layer on the surface of the substrate 35 being transported in close contact with the roller 36. The slot die coater 30 can improve coating quality by forming a coating layer with a uniform width in a direction perpendicular to the transport direction of the substrate 35.

[0111] A coating method using the slot die coater 30 will now be described.

[0112] FIG. 8 is a process diagram conceptually illustrating a coating method according to an embodiment of the present invention.

[0113] First, a substrate 35 is prepared, which has a pair of short sides and a pair of long sides extending between the pair of short sides. The short sides extend in the X-axis direction, and the long sides extend in the Y-axis direction. Only a portion of the substrate 35 is shown in the drawing.

[0114] Next, multiple first coating layers C1 are formed on one surface of the substrate 35 along the long side direction (Y-axis direction), spaced apart at regular intervals along the width direction (X-axis direction). At this stage, uncoated portions 35a extending along the long side direction (Y-axis direction) are formed between adjacent first coating layers C1 in the width direction (X-axis direction). Here, the uncoated portions 35a refer to regions of the substrate 35 where no first coating layer C1 is present. The uncoated portions 35a have a strip shape extending in the long side direction (Y-axis direction).

[0115] Next, a slot die coater 30 according to an embodiment of the present invention is prepared.

[0116] Next, as shown in FIG. 6, while the substrate 35 is being transported using rollers 36, a slot die coater 30 is used to simultaneously form a second coating layer C2 in the transport direction of the substrate 35, covering the boundaries between each of the first coating layers C1 and the non-coated portions 35a.

[0117] When the slot die coater 30 includes a plurality of spacer shims 10, the second coating layer C2 may be formed in a plurality of pairs. The pair of second coating layers C2 may face each other in the short side direction (X-axis direction) with the non-coated portion 35a interposed therebetween.

[0118] In one example, when the number of spacer shims 10 is seven in total, the number of pairs of second coating layers C2 formed on the substrate 35 may be seven in total.

[0119] The slot die coater 30 may be supplied with the coating liquid using a plurality of pumps 37. The number of pumps 37 corresponds to the number of spacer shims 10. Each pump 37 may independently supply the coating liquid from the coating liquid supply unit 33 to each spacer shim 10. In this case, the spray pressure of the coating liquid discharged from the first discharge trench 12b1 and the second discharge trench 12b2 may be maintained uniform while the second coating layer C2 is being formed. When the spray pressure of the coating liquid is uniform, the width of the coating layer may be formed uniformly along the transport direction of the substrate 35.

[0120] In a preferred embodiment, the substrate 35 is a metal foil current collector, the first coating layer C1 is a coating layer of an electrode active material, and the second coating layer C2 is an insulating coating layer.

[0121] The metal foil current collector may be a copper foil current collector or an aluminum foil current collector. The electrode active material may be a positive electrode active material or a negative electrode active material known in the art.

[0122] Next, comparative examples and examples of the present invention will be described.

[0123] FIG. 9 is a photograph of a portion of a current collector 35 immediately after forming a positive electrode active material layer C1 and an insulating coating layer C2 on one side of the current collector 35 made of aluminum foil using a slot die coater 30 including a spacer shim designed to uniformly set the depths of the bending trenches 12c1 and 12c2, the first connection trench 12d1, the second connection trench 12d2, the bridge trench 12e, the first discharge trench 12b1, and the second discharge trench 12b2 to 1.0 mm.

[0124] 9, it was found that the insulating coating layer C2 did not overlap with the positive electrode active material layer C1, and that there were some closely separated coating sections. This indicates that there is a limit to uniformly controlling the width of the coating layer in the direction perpendicular to the running direction of the substrate when the depth of the flow path portion 12 is designed to be constant along the longitudinal direction (Y-axis direction) of the spacer shim 10.

[0125] For reference, if a portion of the insulating coating layer C2 does not overlap with the positive electrode active material layer C1, the insulating coating layer C2 will not function properly. The current collector 35 can be manufactured into a positive electrode by cutting the center of the uncoated portion 35a. It can also be used to manufacture a jelly-roll type electrode assembly together with a positive electrode separator and a negative electrode. In this case, the portion of the insulating coating layer C2 that does not overlap with the positive electrode active material layer C1 may come into contact with the edge of the negative electrode active material facing the separator, causing an internal short circuit.

[0126] FIG. 10 is a photograph of a current collector 35 immediately after forming a positive electrode active material layer C1 and an insulating coating layer C2 on the current collector 35 made of aluminum foil using a slot die coater 30 including a spacer shim 10 designed so that the depths of the bent trenches 12c1 and 12c2 are 1 mm, the depth of the first section (1) of the first connection trench 12d1 and the second connection trench 12d2 are 1 mm, the depth of the third section (3) of the first connection trench 12d1 and the second connection trench 12d2 are 0.5 mm, the length of the second section (2) of the first connection trench 12d1 and the second connection trench 12d2 is 10 mm, and the depths of the bridge trench 12e and the first discharge trench 12b1 and the second discharge trench 12b2 are 0.5 mm, according to an embodiment of the present invention.

[0127] 10, it can be seen that the insulating coating layer C2 overlaps the positive electrode active material layer C1 with a uniform width. Furthermore, the insulating coating layer C2 does not overlap the positive electrode active material layer C1 over the entire area of ​​the current collector 35, and no closely spaced coating areas were observed. This suggests that when a coating layer is formed using a slot die coater 30 including a spacer shim 10 according to the present invention, the coating layer can be formed with a uniform width in the direction perpendicular to the substrate running direction.

[0128] 11 is a graph showing the average thickness of the insulating coating layer for each uncoated line when seven lines of positive electrode active material were coated on one surface of an aluminum current collector at 10 mm intervals with a width of 125.5 mm, and then six pairs of insulating coating layers were formed on six uncoated lines using the slot die coater used in the comparative examples and examples of the present invention. In this graph, the horizontal axis represents the coating line index, and the vertical axis represents the width (mm) of the insulating coating layer.

[0129] Referring to FIG. 11, the width of the insulating coating layer in the example is relatively larger than that of the comparative example. This is because the depth of the flow path portion of the spacer shim 10 in the example decreases stepwise or gradually along the direction of coating liquid movement, increasing the spray pressure of the coating liquid. Therefore, it can be seen that the present invention can increase the controllable width of the coating layer. Furthermore, the line width deviation of the insulating coating layer formed in the example is smaller than that of the insulating coating layer formed in the comparative example. Therefore, the present invention can minimize line width deviation of the coating layer when simultaneously forming multiple coating layers using a slot die coater 30 including multiple spacer shims 10.

[0130] Although the present invention has been described above with reference to limited examples and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary skill in the art to which the present invention pertains to make various modifications and variations within the scope of the technical concept of the present invention and the scope of the claims. [Explanation of symbols]

[0131] 10 spacer shims 10' spacer shim 11 Shim body 12 Flow path section 12a Inflow trench 12b1 First discharge trench 12b2 Second discharge trench 12c1 First bend trench 12c2 Second bend trench 12d1 First Connection Trench 12d2 Second connection trench 12e Bridge Trench 12e' Bridge Trench 20 Right-angle corners 20' Right Angle Corner 21 Round Corner 21' Round Corner 21a Curve section 21b Straight section 22 Fastening holes 30 Slot Die Coater 31 First slot die block 32 Second slot die block 33 Coating liquid supply section 33a Coating liquid introduction chamber 33b Coating liquid inlet hole 33c Coating liquid supply pipe 34 Bolt fastening structure 34a Bolt fastening hole 34b Bolt guide hole 34c bolt 35 Current collector (substrate) 35a Uncoated part 36 Roller 37 Pump C1 First coating layer (positive electrode active material layer) C2 Second coating layer (insulating coating layer) d1 1st separation distance (maximum separation distance) d2 Second separation distance (maximum separation distance) d3 Third separation distance (maximum separation distance) E cross section Z direction θ angle

Claims

1. a plate-shaped shim body having a predetermined width, length and thickness; a flow path portion formed by a groove recessed in a thickness direction of the shim body on one surface of the shim body, The flow path portion is an inflow trench into which the coating liquid flows in the thickness direction; a first discharge trench and a second discharge trench spaced apart from each other in a width direction of the shim body, the first discharge trench and the second discharge trench independently discharging a coating liquid in a longitudinal direction of the shim body; a first bending trench and a second bending trench branching from one side and the other side of the inflow trench, respectively, and extending along the width direction and the length direction; a first connection trench and a second connection trench extending in the longitudinal direction from the first bending trench and the second bending trench, respectively, and communicating with the first discharge trench and the second discharge trench;

2. the first discharge trench and the first connection trench are spaced apart from each other in the width direction and do not overlap each other in the longitudinal direction; The spacer shim according to claim 1 , wherein the second discharge trench and the second connection trench are spaced apart from each other in the width direction and do not overlap each other in the length direction.

3. When the average flow path width of the first bending trench and the average flow path width of the second bending trench are defined as a first flow path width, the average flow path width of the first connection trench and the average flow path width of the second connection trench are defined as a second flow path width, and the average flow path width of the first discharge trench and the average flow path width of the second discharge trench are defined as a third flow path width, The spacer shim of claim 1 , wherein the first flow path width is greater than the second flow path width, and the second flow path width is greater than the third flow path width.

4. When a maximum separation distance in the width direction between the first bending trench and the second bending trench is defined as a first separation distance, a maximum separation distance in the width direction between the first connection trench and the second connection trench is defined as a second separation distance, and a maximum separation distance in the width direction between the first discharge trench and the second discharge trench is defined as a third separation distance, The spacer shim of claim 1 , wherein the first separation distance is less than the second separation distance, and the second separation distance is less than the third separation distance.

5. the flow path portion further includes a bridge trench; one end of the bridge trench is interposed between the first discharge trench and the first connection trench; The spacer shim of claim 1 , wherein the other end of the bridge trench is interposed between the second discharge trench and the second connection trench.

6. The spacer shim of claim 5 , wherein a channel width of the bridge trench is greater than a channel width of the first discharge trench and a channel width of the second discharge trench.

7. The spacer shim of claim 5 , wherein the depth of the bridge trench is substantially the same as the depth of the first discharge trench and the depth of the second discharge trench.

8. the flow path portion further includes a bridge trench; One end of the bridge trench communicates with the first connection trench; The spacer shim of claim 1 , wherein the other end of the bridge trench communicates with the second connection trench.

9. The spacer shim according to claim 8 , wherein a channel width of the bridge trench is smaller than a channel width of the first connection trench and a channel width of the second connection trench.

10. The spacer shim of claim 8 , wherein the bridge trench communicates with the first connection trench and the second connection trench at the same depth.

11. The spacer shim of claim 5 , wherein the bridge trench intersects the first discharge trench and the second discharge trench substantially perpendicularly, and a channel width at the intersection decreases toward the discharge trench.

12. The spacer shim according to claim 11 , wherein the flow passages at the intersection have a structure in which an inner right-angled corner and an outer rounded corner face each other.

13. the first connection trench and the second connection trench each include a first section having a first average depth, a second section having a second average depth, and a third section having a third average depth along a longitudinal direction of the shim body; the first average depth is greater than the second average depth; The spacer shim of claim 1 , wherein the second average depth is greater than the third average depth.

14. The first section and the third section each have a trench depth that is substantially the same along a flow direction of the coating liquid; The spacer shim of claim 13 , wherein the second section has a trench whose depth decreases along a flow direction of the coating liquid.

15. The spacer shim of claim 13 , wherein the depth of the trench in the third section is substantially the same as the depth of the first and second discharge trenches.

16. 2. The spacer shim according to claim 1, wherein the trench constituting the flow path portion has a rounded bottom when viewed from a cross section perpendicular to the direction in which the coating liquid flows.

17. The spacer shim according to claim 1 , further comprising at least one fastening hole passing through the shim body so as not to overlap with the flow passage portion.

18. The spacer shim according to claim 1 , further comprising a coating layer formed on the exposed surface of the flow path portion in a thickness direction of the shim body.

19. 20. The spacer shim of claim 18, wherein the coating layer comprises polytetrafluoroethylene.

20. At least one spacer shim according to any one of claims 1 to 19; a first slot die block coupled to one side of the shim body so as to face the exposed surface of the flow path portion in a thickness direction of the shim body; a second slot die block coupled to the other side of the shim body so as to face the first slot die block; a coating liquid supply in communication with the inlet trench of the spacer shim.

21. 21. The slot die coater of claim 20, comprising at least one pump that independently supplies coating liquid from a coating liquid supply that communicates with the inlet trench of each spacer shim.

22. A first step of providing a substrate having a pair of short sides and a pair of long sides extending between the pair of short sides; forming a plurality of first coating layers at predetermined intervals on one surface of the substrate along a long side direction of the substrate, wherein a strip-shaped uncoated portion extending along the long side direction is formed between adjacent first coating layers in a short side direction of the substrate; Providing a slot die coater according to claim 20; and forming a second coating layer along the long side direction using the slot die coater, the second coating layer covering the boundary between each first coating layer and an adjacent uncoated portion by a predetermined width.

23. The coating method according to claim 22, wherein the second coating layer is simultaneously formed as a pair at a boundary between a pair of first coating layers facing the non-coated portion and the non-coated portion.

24. the substrate is a metal foil current collector; the first coating layer is an active material coating layer, 23. The coating method of claim 22, wherein the second coating layer is an insulating coating layer.

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