Slot die coater and electrode coating device including same

Abstract

A slot die coater and an electrode coating device including the same are disclosed. The slot die coater according to one embodiment of the present invention is an apparatus configured to discharge a coating material onto a surface of a substrate, and includes a first die having a first surface, a second die having a second surface facing the first surface, and a shim plate interposed between the first surface of the first die and the second surface of the second die and configured to form a slot through which the coating material is discharged, and the second die includes a pair of guide lips protruding from both ends of an opening of the slot toward the substrate.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0092930, filed on July 27, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof.

[0002] The present invention relates to a slot die coater and an electrode coating apparatus including the same, and more particularly to a slot die coater that discharges a coating material onto a surface of a substrate through a slot and an electrode coating apparatus including the same. [Background technology]

[0003] Generally, an electrode assembly for a secondary battery capable of repeated charging and discharging is manufactured by stacking or winding a plurality of laminated structures each including a first electrode corresponding to a cathode, a second electrode corresponding to an anode, and a separator sandwiched between them. In this case, each electrode is manufactured by coating a slurry-like coating material containing a cathode active material or an anode active material on an aluminum or copper electrode substrate and then drying it.

[0004] Recently, a slot die coater has been mainly used in the coating process of such electrode substrates. A slot die coater is a device that coats the surface of a substrate by discharging a coating material through a slot.

[0005] However, as disclosed in Patent Document 1, the existing technology applies pressure to the inside of a slot die coater and discharges the coating material contained inside the slot die coater through a slot opening that has a relatively wide width and a relatively very low height. Therefore, when actually applied to a coating process, the width of the discharged coating material becomes even wider than the width of the slot opening due to the discharge pressure and atmospheric pressure, resulting in a problem that the results differ from the design.

[0006] Furthermore, the existing technology has a problem in that the width of the extruded coating material varies due to the pulsation of pressure applied inside the slot die coater. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2019-0060557 Summary of the Invention [Problem to be solved by the invention]

[0008] The technical problem to be solved by the present invention is to provide a slot die coater and an electrode coating apparatus including the same, which can prevent the phenomenon that the width of the coating material discharged onto the surface of the substrate through the slot becomes wider than the width of the slot opening due to the discharge pressure and atmospheric pressure, and the phenomenon that the width of the coating material varies due to pulsation of the discharge pressure. [Means for solving the problem]

[0009] A slot die coater according to one embodiment of the present invention is an apparatus configured to eject a coating material onto a surface of a substrate, and includes a first die having a first surface, a second die having a second surface facing the first surface, and a shim plate interposed between the first surface of the first die and the second surface of the second die and configured to form a slot through which the coating material is ejected, and the second die has a pair of guide lips protruding from both ends of the opening of the slot toward the substrate.

[0010] In one embodiment, the pair of guide lips may be configured to contact both side edge portions of the coating material dispensed onto the surface of the substrate and guide the movement of the coating material as the substrate moves.

[0011] In one embodiment, the first die may further include a receiving groove configured to receive the coating material and to communicate with the slot.

[0012] In one embodiment, the first die may include a main body portion having the first surface and having the opening located at its tip, and a support portion extending from the rear end of the main body portion toward the second die and supporting the second die.

[0013] In one embodiment, the first die may include a first die lip that protrudes toward the substrate and forms one side wall of the opening.

[0014] In one embodiment, the second die further includes a second die lip that protrudes from between the pair of guide lips toward the substrate and forms the other side wall of the opening, and the pair of guide lips can be configured to protrude toward the substrate in a longer length than the second die lip.

[0015] In one embodiment, the pair of guide lips may be formed so that the length of the pair of guide lips protruding toward the substrate is longer than the second die lip in the range of 100 μm or more and 300 μm or less.

[0016] In one embodiment, the pair of guide lips and the second die lip each protrude toward the substrate with a predetermined thickness, and the pair of guide lips can be configured to be thicker than the second die lip.

[0017] In one embodiment, the second die further includes a second die lip that protrudes from between the pair of guide lips toward the substrate and forms the other side wall of the opening, and the first die lip may be configured to protrude toward the substrate in a longer length than the second die lip.

[0018] In one embodiment, the second die includes a first die block arranged at a certain gap from the first die to form the slot; a second die block having a first guide lip of the pair of guide lips and arranged on one side of the first die block; and a third die block having a second guide lip of the pair of guide lips and arranged on the other side of the first die block, wherein the first die block includes a first support protrusion protruding from one side surface of the first die block facing the second die block toward the second die block, and a second support protrusion protruding from the other side surface of the first die block facing the third die block toward the third die block, wherein the second die block may further include a first support groove configured to accommodate the first support protrusion and support the first die block, and the third die block may further include a second support groove configured to accommodate the second support protrusion and support the first die block.

[0019] An electrode coating apparatus according to one embodiment of the present invention is an apparatus including a slot die coater according to any one of the above-described embodiments, and may be configured to coat an electrode substrate using the slot die coater. [Effects of the Invention]

[0020] According to the present invention, a pair of guide lips protruding from both ends of the width direction of the slot opening toward the substrate to be coated come into contact with both side edge portions of the coating material discharged onto the surface of the substrate, preventing the coating material from spreading in the lateral direction and guiding the movement of the coating material as the substrate moves. This minimizes the phenomenon in which the width of the discharged coating material becomes even wider than the width of the slot opening due to the discharge pressure or atmospheric pressure, and prevents the width of the discharged coating material from varying due to pulsations in the discharge pressure.

[0021] Furthermore, of the two die lips that form the opening of the slot, the first die lip that encounters the substrate moving in one direction relatively first is configured to protrude further toward the substrate than the second die lip that encounters the substrate relatively later. This prevents the coating material discharged through the slot from leaking in the opposite direction to the substrate's movement due to discharge pressure or atmospheric pressure.

[0022] Furthermore, among the first and second dies that make up the slot die coater, the second die having the pair of guide lips is configured by combining a first die block that forms a slot with the first die, a second die block that has the first of the pair of guide lips, and a third die block that has the second of the pair of guide lips.This makes it possible to easily realize a minute step structure formed between the pair of guide lips and the opening of the slot without high-precision processing, thereby improving the precision of the slot die coater while reducing manufacturing time and costs.

[0023] Furthermore, by providing a support structure that supports the first die block so that a gap between the first die and the first die block of the second die is maintained without using any additional fastening members, the durability and reliability of the slot die coater can be ensured even when the slot die coater is manufactured using the second die that is not integrated but is formed by bonding between the die blocks.

[0024] Furthermore, it should be clear to those skilled in the art that the various embodiments of the present invention can solve various technical problems not mentioned above. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view showing a slot die coater according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view showing the M1 region of FIG. [Figure 3] FIG. 2 is an exploded perspective view showing the slot die coater shown in FIG. 1. [Figure 4] 2 is a cross-sectional view of the slot die coater shown in FIG. 1 taken along line AA'. FIG. [Figure 5] 2 is a cross-sectional view of the slot die coater shown in FIG. 1 taken along line BB'. [Figure 6] FIG. 6 is an enlarged view showing the M2 region of FIG. 5. [Figure 7] FIG. 2 is a cross-sectional view showing a lip structure of a slot die coater according to a modified embodiment of the present invention. [Figure 8] FIG. 1 is a diagram showing a coating method of a slot die coater according to one embodiment of the present invention. [Figure 9] FIG. 1 is a diagram showing a coating layer formed by a conventional slot die coater. [Figure 10] FIG. 2 illustrates a coating layer formed by a slot die coater according to one embodiment of the present invention. [Figure 11] FIG. 2 shows a second die of a slot die coater according to a modified embodiment of the present invention. [Figure 12] 1 illustrates an electrode coating apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] In order to clarify the solution to the technical problem of the present invention, the following embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, when describing the present invention, detailed descriptions of known technologies related to the present invention may obscure the gist of the present invention, such detailed descriptions will be omitted. Furthermore, the terms used in this specification are defined in consideration of the functions of the present invention, and may vary depending on the intentions or practices of users or operators. Therefore, it is appropriate that the definitions of the terms described below be defined in consideration of the overall content of this specification.

[0027] Meanwhile, in the accompanying drawings, the same reference numerals refer to the same components, and the dimensions of the components or parts of the components of the present invention shown in the accompanying drawings may be slightly exaggerated, reduced, or simplified in order to effectively explain the technical features of the present invention.

[0028] FIG. 1 shows a perspective view of a slot die coater 10 according to one embodiment of the present invention.

[0029] 1, a slot die coater 10 according to an embodiment of the present invention may be configured to coat a surface of a target substrate by discharging a coating material through a slot 12 on a transport path of the target substrate, which is transported in one direction by a predetermined transport means. To this end, the slot die coater 10 may include a first die 100, a second die 200, and a shim plate 300.

[0030] The first die 100 may have a first surface facing the second die 200 and may be configured to be coupled with the second die 200 to form a receiving space for receiving a coating substance.

[0031] In this case, the first die 100 may include a main body 110 having the first surface and having a slot opening 12a at its tip, and a support 120 extending from the rear end of the main body 110 toward the second die 200 and configured to support the second die 200. The main body 110 of the first die 100 may also include a first die lip 112 that protrudes toward the target substrate (in the X-axis direction) and forms one side wall of the opening 12a.

[0032] The opening 12a located at the end of the slot 12 has a predetermined height and width, but may have a width that is significantly larger than the height. As will be explained again below, the width of the opening 12a located at the end of the slot 12 may correspond to the width of the coating layer to be formed on the surface of the substrate.

[0033] The second die 200 has a second surface facing the first surface of the first die 100 and can be configured to be coupled with the first die 100 to form a storage space for storing the coating material.

[0034] The second die 200 may also include a pair of guide lips 222, 232 that protrude from both ends of the opening 12a in the width direction toward the target substrate (in the X-axis direction).

[0035] The pair of guide lips 222, 232 may be configured to contact both side edge portions in the width direction of the coating material discharged onto the surface of the target substrate, and to guide the movement of the coating material as the target substrate moves while preventing the coating material from spreading toward the edges due to discharge pressure or atmospheric pressure.

[0036] The second die 200 may also include a second die lip 212 that protrudes from between the pair of guide lips 222, 232 toward the target substrate (in the X-axis direction) and forms the other side wall of the opening 12a.

[0037] In this case, the pair of guide lips 222, 232 may be configured to protrude further toward the target substrate than the second die lip 212. As will be described again below, the pair of guide lips 222, 232 may be formed so that the length of their protrusion toward the target substrate is 100 μm or more and 300 μm or less than that of the second die lip 212.

[0038] Furthermore, the first die lip 112 of the first die 100 may be configured to protrude further toward the target substrate than the second die lip 212. In this case, the first die lip 112 may be formed so that the length of its protrusion toward the target substrate is 100 μm or more and 300 μm or less than that of the second die lip 212. Depending on the embodiment, the first die lip 112 may be configured to protrude the same length as the second die lip 212.

[0039] In one embodiment, the second die 200 may include a first die block 210, a second die block 220, and a third die block 230. The second die 200 may be formed by combining the first die block 210, the second die block 220, and the third die block 230. That is, the second die 200 may be formed by combining the three die blocks 210, 220, and 230 so that they are aligned along the width direction of the opening 12a.

[0040] In this case, the first die block 210 may be configured to include the second die lip 212 and to be spaced apart from the first die 100 to form the slot 12 .

[0041] The second die block 220 may include a first guide lip 222 of the pair of guide lips 222 , 232 and may be configured to be disposed on one side of the first die block 210 .

[0042] The third die block 230 may include a second guide lip 232 of the pair of guide lips 222 , 232 and may be configured to be disposed on the other side of the first die block 210 .

[0043] The first die block 210, the second die block 220, and the third die block 230 may be configured to be coupled to the first die 100 by fastening members 214, 224, and 234, such as bolts, respectively.

[0044] In this way, since the second die 200 of the slot die coater 10 is formed by combining die blocks 210, 220, and 230, each of which has only one of a guide lip and a die lip, the minute step structure formed between the pair of guide lips 222, 232 and the second die lip 212 can be easily realized without high-precision processing, thereby improving the precision of the slot die coater while reducing manufacturing time and costs.

[0045] As will be explained again below, the shim plate 300 can be configured to be interposed between the first surface of the first die 100 and the second surface of the second die 200 to form a slot 12 through which the coating material is ejected.

[0046] Meanwhile, the substrate to be coated by the slot die coater 10 may be an electrode substrate used in manufacturing electrodes for secondary batteries. In this case, the electrode substrate may be a metal foil used in manufacturing positive or negative electrodes, or a polyethylene (PE) or polypropylene (PP) sheet used in manufacturing separators.

[0047] The coating material discharged from the slot die coater 10 may be a slurry containing a conductive agent and a binder together with a positive or negative active material, or may be a coating material containing a ceramic material. In this case, the positive active material may be LiCoO2, LiMn2O4, LiFePO4, LiNiCoAlO2, LiNiMnCoO2, or Li2TiO3. The negative active material may be natural graphite, artificial graphite, or low-crystalline carbon.

[0048] FIG. 2 shows an enlarged view of the M1 region of FIG.

[0049] As shown in FIG. 2, the first die lip 112 of the first die 100 and the second die lip 212 of the first die block 210 of the second die 200 can be spaced apart by a gap corresponding to the thickness of the shim plate 300 to form a slot opening 12a through which the coating material is discharged.

[0050] Furthermore, the first guide lip 222 of the second die block 220 arranged on one side of the first die block 210 may protrude further toward the substrate, i.e., in the direction of extrusion of the coating material, than the slot opening 12a or the second die lip 212 of the first die block 210.

[0051] In this way, the first step surface formed by the difference in protruding length between the first guide lip 222 and the second die lip 212 serves to guide the movement of the coating material discharged through the slot opening 12a.

[0052] Similarly, a second step surface formed by the difference in protrusion length between the second guide lip 232 of the second die block 220 and the second die lip 212 also serves to guide the movement of the coating material discharged through the slot opening 12a. In this case, the first step surface of the first guide lip 222 and the second step surface of the second guide lip 232 may be formed by flat surfaces facing each other in parallel.

[0053] Furthermore, the protruding lengths of the first guide lip 222 and the second guide lip 232 may be the same.

[0054] FIG. 3 shows an exploded perspective view of the slot die coater 10 shown in FIG.

[0055] As shown in FIG. 3, the slot die coater 10 can include a first die 100, die blocks 210, 220, 230, and a shim plate 300.

[0056] As described above, the first die 100 may include a main body portion 110 and a support portion 120. A first die lip 112 forming a slot opening 12a may be provided at the tip of the main body portion 110, and a receiving groove 116 may be provided on a top surface 114 of the main body portion 110 facing the die blocks 210, 220, and 230.

[0057] The receiving groove 116 may be configured to receive a coating material and to communicate with the slot 12. The receiving groove 116 may serve as a manifold for delivering the coating material to the slot 12. To this end, the receiving groove 116 may be configured to be connected to an externally disposed coating material supply chamber (not shown) by a pipe and receive the coating material from the chamber.

[0058] Depending on the embodiment, the main body 110 may have a fastening groove 118 to which a predetermined fastening member used to connect the die blocks 210, 220, 230, the shim plate 300, etc. to the main body 110 is fastened.

[0059] The support part 120 may be configured to extend upward from the rear end of the body part 110 to support the die blocks 210, 220, and 230. In this case, the body part 110 and the support part 120 may be integrally formed.

[0060] The die blocks 210, 220, and 230 coupled to such a first die 100 each have a bottom surface facing the top surface 114 of the first die 100, and can be configured to be coupled to the first die 100 to form a storage space for storing the coating material and a slot 12 for discharging the coating material.

[0061] To this end, the first die block 210 may include a second die lip 212 that forms the slot opening 12a with the first die lip 112 of the first die 100. Depending on the embodiment, the first die block 210 may include mating holes 216 that receive fasteners used to couple the first die block 210 to the first die 100.

[0062] The second die block 220 may include a first guide lip 222 of the pair of guide lips 222, 232 and may be configured to be disposed on one side of the first die block 210. Depending on the embodiment, the second die block 220 may include a mating hole 226 into which a fastener used to couple the second die block 220 to the first die 100 is fitted.

[0063] The third die block 230 may include a second guide lip 232 of the pair of guide lips 222, 232 and may be configured to be disposed on the other side of the first die block 210. Depending on the embodiment, the third die block 230 may include a mating hole 236 into which a fastener used to couple the third die block 230 to the first die 100 is fitted.

[0064] The die blocks 210, 220, and 230 of the first die 100 and the second die 200 may be made of a material including stainless steel. For example, the die blocks 210, 220, and 230 of the first die 100 and the second die 200 may be made of a stainless steel material that is easy to process and has excellent corrosion resistance, such as SUS304, SUS316L, SUS420J2, SUS440C, or SUS630.

[0065] The shim plate 300 may be configured to be interposed between the top surface of the first die 100 and the bottom surfaces of the die blocks 210, 220, and 230 to form the slot 12 through which the coating material is discharged. The shim plate 300 determines the shape of the slot 12 through which the coating material is discharged, and may also function as a gasket to prevent the coating material from leaking to the outside from portions of the slot die coater 10 other than the slot 12.

[0066] For this purpose, the shim plate 300 may have a plate structure that entirely covers the top surface 114 of the first die 100. The shim plate 300 may have a hollow 310 at its center that has a shape corresponding to the receiving groove 116 of the first die 100, and an opening 320 that communicates with the hollow 310 at one side thereof.

[0067] Such a shim plate 300 can determine the shape of the slot opening 12a through which the coating material is discharged. That is, the thickness Ts of the shim plate 300 can determine the height of the slot opening 12a, and the width Ws of the opening of the shim plate 300 can determine the width of the slot opening 12a.

[0068] Depending on the embodiment, the shim plate 300 may include mating holes 302 that receive fasteners used to couple the shim plate 300 to the first die 100 .

[0069] FIG. 4 shows a cross-sectional view of the slot die coater 10 shown in FIG. 1 taken along line AA'.

[0070] 4, a third die block 230 corresponding to a side portion of the second die 200 may be coupled to the first die 100 with a shim plate 300 sandwiched therebetween. A guide lip 232 of the third die block 230 may protrude in the substrate direction (X-axis direction). In this case, the die lip 112 of the first die 100 may protrude to the same length as the guide lip 232 of the third die block 230.

[0071] Depending on the embodiment, the die lip 112 of the first die 100 may be configured to protrude further than the guide lip 232 of the die block 230 .

[0072] The second die block 220 corresponding to the other side portion of the second die 200 may have a structure corresponding to that of the third die block 230 described above.

[0073] FIG. 5 shows a cross-sectional view of the slot die coater 10 shown in FIG. 1 taken along line BB'.

[0074] As shown in FIG. 5 , the first die block 210, which corresponds to the central portion of the second die 200, can be coupled to the first die 100 with a shim plate 300 sandwiched therebetween to form a slot 12 that communicates with the receiving groove 116 of the first die 100.

[0075] That is, the rear end of the first die block 210 may be coupled to and supported by the first die 100 with the shim plate 300 sandwiched therebetween. Meanwhile, the front end of the first die block 210 may be spaced apart from the first die 100 by a gap corresponding to the thickness of the shim plate 300, thereby forming the slot 12.

[0076] Meanwhile, the die lip 112 of the first die 100 and the die lip 212 of the die block 210 may form the slot opening 12a. As described above, the height of the opening 12a may correspond to the thickness of the shim plate 300, and the width of the opening 12a may correspond to the width of the opening 320 provided in the shim plate 300.

[0077] The coating material discharged through the opening 12a of the slot thus formed can be guided by guide lips 222 and 232 protruding from both ends of the opening 12a in the width direction.

[0078] FIG. 6 shows an enlarged view of the M2 region of FIG.

[0079] As shown in FIG. 6, the first die lip 112 provided on the first die 100 and the second die lip 212 provided on the first die block 210 of the die blocks 210, 220, 230 of the second die 200 can form a slot opening 12a through which the coating material is ejected.

[0080] In this case, the length L1 of the first die lip 112 may be formed to be longer than the length L2 of the second die lip 212. In another embodiment, the length L1 of the first die lip 112 may be formed to be the same length as the length L2 of the second die lip 212.

[0081] On the other hand, the first guide lip 222 of the second die block 220 may have a constant thickness and may protrude from the opening 12a toward the substrate by a length corresponding to a predetermined length Lg. That is, the first guide lip 222 may protrude further toward the substrate than the second die lip 212, which determines the position of the opening 12a. In other words, the second die lip 212 may be formed shorter than the first guide lip 222.

[0082] In this case, the difference in length (Lg-L2) between the guide lip 222 and the second die lip 212 can be determined in the range of 100 μm or more and 300 μm or less.

[0083] If the difference in length (Lg-L2) is less than 100 μm, the both side edges of the coating material discharged onto the surface of the target substrate will be exposed to the atmosphere with almost no contact with the first guide lip 222, which may cause the width of the discharged coating material to become wider than the width of the opening 12a, and may even vary.

[0084] On the other hand, if the length difference (Lg-L2) exceeds 300 μm, the opening 12a must be spaced a certain distance from the target substrate to ensure a minimum gap between the first guide lip 222 and the target substrate, making it difficult to adjust the thickness of the coating layer formed on the target substrate.

[0085] The coating gap is the distance between the end of the die lip and the substrate. This coating gap affects the coating bead pressure during coating, which in turn affects the coating width. When the coating gap changes, the width of both side edges of the coating material changes until they reach equilibrium with atmospheric pressure.

[0086] In the present invention, because the second die lip 212 is shorter than the first guide lip 222, the coating gap at the end of the first guide lip 222 is smaller than the coating gap at the end of the second die lip 212. Therefore, the edge portion of the coating material in contact with the first guide lip 222 has a smaller area that encounters air and is less susceptible to pressure changes. As a result, deformation of the edge portion in contact with the first guide lip 222 is reduced, and the uniformity of the overall coating width can be ensured.

[0087] The protruding lengths of the first guide lip 222 and the second guide lip 232 may be the same. Therefore, the effect of making the coating width uniform due to the difference in length between the first guide lip 222 and the second die lip 212 can be obtained similarly between the second guide lip 232 and the second die lip 212.

[0088] 6 shows the length Lg of the first guide lip 222 and the length L1 of the first die lip 112 as being the same or approximately the same, but depending on the embodiment, the length Lg of the first guide lip 222 may be formed to be even longer than the length L1 of the first die lip 112. In this case, the difference in length between the first guide lip 222 and the first die lip 112 (Lg-L2) may be determined to be in the range of 100 μm or more and 300 μm or less.

[0089] FIG. 7 shows a cross-sectional view of a lip structure of a slot die coater according to a modified embodiment of the present invention.

[0090] 7, the guide lip 222' may have a predetermined thickness Tg and may protrude toward the substrate. The second die lip 212 may also have a predetermined thickness Td and may protrude toward the substrate. In this case, the guide lip 222' may be formed thicker than the second die lip 212.

[0091] As will be explained again below, the coating material dispensed onto the surface of the target substrate through the slot opening 12a moves along the target substrate in the thickness direction of the guide lip 222' (e.g., upward in FIG. 7). Therefore, the thicker the thickness Tg of the guide lip 222', the longer the distance the dispensed coating material is guided by the guide lip 222'. As a result, the effect of the guide lip 222' in preventing the dispensed coating material from spreading to both sides in the width direction and guiding the movement of the dispensed coating material while making the edges of the dispensed coating material uniform can be further improved.

[0092] FIG. 8 shows a coating method of a slot die coater according to one embodiment of the present invention.

[0093] As shown in Figure 8, the coating material C ejected onto the surface of the substrate E through the slot opening 12a can spread in the width direction (or CD direction) of the substrate E or the coating material C, which intersects with the movement direction (or MD direction) of the substrate E, due to the ejection pressure and atmospheric pressure.

[0094] In this case, the guide lip 222 can guide the movement of the coating material C as the target substrate E moves while blocking the spread of the discharged coating material C. This prevents the coating width from changing. Furthermore, since the coating material C does not immediately spread upon leaving the slot opening 12a but is guided by the guide lip 222 to form a coating bead, sliding, which would otherwise occur if the edge of the coating material collapsed to form a smooth boundary, can be alleviated, and the reproducibility of the sliding can be improved.

[0095] On the other hand, the coating material C discharged onto the surface of the target substrate E through the slot opening 12a may leak in the opposite direction of the target substrate E's movement due to the discharge pressure and atmospheric pressure. This instability, in which a portion of the coating material flows upstream outside the die lip, is called leakage. Such leakage represents a loss of the pre-measured coating material, making the final coating thickness unpredictable. Such leakage can cause the coating material to stagnate and solidify over a long period of time or cause variations in the coating thickness across the width. In particular, when the coating material is discharged under high pressure with a coating gap as small as several hundred microns in order to achieve a thin coating or to reduce variations in the coating layer's thickness across the width, the risk of severe leakage is a concern.

[0096] In this case, the first die lip 112 protruding from the slot opening 12a toward the substrate E comes into contact with the discharged coating material C, preventing the coating material C from leaking in the opposite direction. This not only minimizes leakage, but also prevents the coating width from varying due to pulsation in the discharge pressure, and improves the repeatability of sliding in relation to the edge of the coating material.

[0097] FIG. 9 shows a coating layer formed by a conventional slot die coater 20 .

[0098] As shown in Figure 9, the width Wc1 of the coating material C1 ejected onto the surface of the substrate E through the slot 22 of a conventional slot die coater 20 becomes wider than the width Ws1 of the opening of the slot 22 due to the ejection pressure and atmospheric pressure, resulting in a result that differs from the design intention.

[0099] Furthermore, the width Wc1 of the coating material C1 is irregular due to the pulsation of the pressure that discharges the coating material C1.

[0100] FIG. 10 shows a coating layer formed by a slot die coater 10 according to one embodiment of the present invention.

[0101] As shown in FIG. 10, the slot die coater 10 according to one embodiment of the present invention includes a pair of guide lips 222, 232 that protrude from both ends of the slot opening 12a toward the substrate E with a certain thickness.

[0102] The pair of guide lips 222, 232 contact both side edge portions of the coating material C2 discharged onto the surface of the substrate E, and prevent the coating material C2 from spreading in the width direction (or CD direction). As a result, it is possible to minimize the difference between the width Ws2 of the slot opening 12a and the width Wc2 of the coating material C2 discharged through the opening 12a.

[0103] In addition, the pair of guide lips 222, 232 guide the movement of the coating material C2 through the parallel stepped surfaces facing each other, thereby making the edge of the coating material C2 uniform, thereby preventing the width Wc2 of the coating material C2 from varying due to pressure pulsation when discharging the coating material C2.

[0104] As described above, the slot die coater 10 according to the present invention is less sensitive to factors that cause changes in coating width compared to conventional slot die coaters, and is therefore able to perform a coating process without changes in coating width.

[0105] FIG. 11 shows a second die 200' of a slot die coater according to a modified embodiment of the present invention.

[0106] As shown in FIG. 11, a second die 200′ of a slot die coater according to a modified embodiment of the present invention may include a first die block 210′ ​​forming its central portion, and a second die block 220′ and a third die block 230′ forming its side portions.

[0107] In this case, the first die block 210' may have a first support protrusion 218a protruding from one side surface facing the second die block 220' toward the second die block 220', and a second support protrusion 218b protruding from the other side surface facing the third die block 230' toward the third die block 230'.

[0108] The second die block 220' may include a first support groove 228 configured to receive the first support protrusion 218a of the first die block 210' and support the first die block 210'.

[0109] The third die block 230' may include a second support groove 238 configured to receive the second support protrusion 218b of the first die block 210' to support the first die block 210'.

[0110] In this way, support structures 218a, 218b, 228, 238 are provided to support the first die block 210' so that a gap between the first die 100 and the first die block 210' of the second die 200' is maintained without using any additional fastening members, thereby ensuring the durability and reliability of the slot die coater even when the slot die coater is manufactured using a second die 200' that is not integral but is formed by bonding between the die blocks.

[0111] FIG. 12 shows an electrode coating apparatus 400 according to one embodiment of the present invention.

[0112] As shown in FIG. 12, the electrode coating apparatus 400 includes a slot die coater 10 according to one embodiment of the present invention, and can be configured to coat the surface of an electrode substrate using the slot die coater 10.

[0113] For this purpose, the electrode coating apparatus 400 may further include a conveying unit 410 , a drying unit 420 and a control unit 430 .

[0114] The conveying unit 410 may be configured to convey the electrode substrate E used in the manufacture of an electrode to the drying unit 420 via the slot die coater 10. For this purpose, the conveying unit 410 may include an unwinder 412, a conveying roll 414, a rolling roll 416, and a rewinder 418.

[0115] The unwinder 412 may generally be configured to unwind and move the electrode substrate E wound in a roll. In this case, the unwinder 412 may include a wheel to which the rolled electrode substrate E is fixed, and a motor (not shown) that rotates the wheel in a predetermined direction and speed to unwind the electrode substrate E fixed to the wheel. In this specification, the term "electrode substrate" may refer to various sheets used in manufacturing electrode assemblies for secondary batteries, such as a sheet for manufacturing a positive electrode, a sheet for manufacturing a negative electrode, a sheet for manufacturing a separator, etc.

[0116] The transport rolls 414 may be configured to be arranged at various positions in the electrode coating apparatus 400 to facilitate the movement of the electrode substrate E.

[0117] The rolling roll 416 may be configured to roll the electrode substrate E on which the coating layer is formed and which has been dried by the drying unit 420 .

[0118] The rewinder 418 may be configured to rewind the rolled electrode substrate E. To this end, the rewinder 418 may include a wheel for rewinding the rolled electrode substrate E, a motor (not shown) for rotating the wheel in a predetermined direction and speed to rewind the rolled electrode substrate E, and the like.

[0119] Depending on the embodiment, the electrode coating apparatus 400 may be configured to perform a slitting process before the electrode substrate E rolled by the rolling roll 416 is transported to a rewinder 418 .

[0120] Meanwhile, the slot die coater 10 can apply a coating material to the surface of the electrode substrate E that is unwound and transported by the unwinder 412.

[0121] The drying unit 420 may be configured to dry the electrode substrate E on which the coating substance has been applied.

[0122] For this purpose, the drying unit 420 may include a chamber 422 having an internal space, a heat unit 424 that applies hot air to the electrode substrate E, and a lamp 426 that radiates electromagnetic waves in a predetermined wavelength band. In this case, the lamp 426 may be a medium wave infrared (MIR) lamp that radiates medium infrared rays in a wavelength band ranging from 1400 nm to 3000 nm.

[0123] The control unit 430 may be configured to control the overall operation of the electrode coating apparatus 400. In particular, the control unit 430 may be configured to control the operation of a heat unit 424 and a lamp 426 disposed in a chamber 422 of a drying unit 420.

[0124] To this end, the control unit 430 may optionally include hardware such as a general-purpose processor, application specific integrated circuits (ASICs), other chipsets, logic circuits, registers, memory, etc. for executing control logic.

[0125] The control unit 430 may further include a temperature sensor 432 that measures the temperature inside the chamber 422 and a gas sensor 434 that measures the gas concentration inside the chamber 422. In this case, the control unit 430 may control the operation of the heat unit 424 and the lamp 426 based on the temperature information measured by the temperature sensor 432 and the gas concentration information measured by the gas sensor 434.

[0126] As described above, according to the present invention, a pair of guide lips protruding from both ends of the width direction of the slot opening toward the substrate to be coated come into contact with both side edge portions of the coating material discharged onto the surface of the substrate, preventing the coating material from spreading in the lateral direction and guiding the movement of the coating material as the substrate moves. This minimizes the phenomenon in which the width of the discharged coating material becomes even wider than the width of the slot opening due to the discharge pressure or atmospheric pressure, and prevents the width of the discharged coating material from varying due to pulsation of the discharge pressure.

[0127] Furthermore, of the two die lips that form the opening of the slot, the first die lip that encounters the substrate moving in one direction relatively first is configured to protrude further toward the substrate than the second die lip that encounters the substrate relatively later, thereby preventing the coating material discharged through the slot from leaking in the opposite direction to the substrate movement due to discharge pressure or atmospheric pressure.

[0128] Furthermore, among the first and second dies that make up the slot die coater, the second die having the pair of guide lips is configured by combining a first die block that forms a slot with the first die, a second die block that has the first of the pair of guide lips, and a third die block that has the second of the pair of guide lips. This makes it possible to easily realize a minute step structure formed between the pair of guide lips and the opening of the slot without high-precision machining, thereby improving the precision of the slot die coater while reducing manufacturing time and costs.

[0129] Furthermore, by providing a support structure that supports the first die block so that a gap between the first die and the first die block of the second die is maintained without using any additional fastening members, the durability and reliability of the slot die coater can be ensured even when the slot die coater is manufactured using the second die that is not integrated but is formed by bonding between the die blocks.

[0130] Furthermore, it goes without saying that the embodiments of the present invention can solve various other technical problems in the technical field in question as well as in related technical fields other than those mentioned in this specification.

[0131] The present invention has been described above with reference to specific embodiments. However, it will be apparent to those skilled in the art that various modified embodiments can be realized within the technical scope of the present invention. Therefore, the embodiments disclosed above should be considered from an illustrative perspective, not a restrictive one. That is, the true technical scope of the present invention is defined by the appended claims, and all differences within the scope of equivalents thereto should be construed as being included in the present invention.

Claims

1. 1. A slot die coater configured to dispense a coating material onto a surface of a substrate, comprising: a first die having a first surface; a second die having a second surface facing the first surface; a shim plate interposed between the first surface of the first die and the second surface of the second die and configured to form a slot through which the coating material is discharged; the second die includes a pair of guide lips protruding from both ends of the opening of the slot toward the substrate, The second die includes: a first die block disposed with a fixed gap from the first die to form the slot; a second die block having a first guide lip of the pair of guide lips and disposed on one side of the first die block; a third die block having a second guide lip of the pair of guide lips and disposed on the other side of the first die block.

2. 2. The slot die coater according to claim 1, wherein the pair of guide lips are configured to contact both side edge portions of the coating material spit out onto the surface of the substrate and guide the movement of the coating material as the substrate moves.

3. The first die includes: The slot die coater of claim 1 , further comprising a receiving groove configured to receive the coating material and to communicate with the slot.

4. The first die includes: a main body portion having the first surface and the opening located at a tip thereof; The slot die coater according to claim 1 , further comprising: a support portion extending from a rear end of the main body portion toward the second die and supporting the second die.

5. The first die includes: The slot die coater according to claim 1 , further comprising a first die lip that protrudes toward the substrate and forms one side wall of the opening.

6. The second die includes: a second die lip protruding from between the pair of guide lips toward the substrate and forming one side wall of the opening; The slot die coater according to claim 1 , wherein the pair of guide lips are configured to protrude toward the substrate in a longer shape than the second die lip.

7. The pair of guide lips are The slot die coater according to claim 6 , wherein the length of the portion protruding toward the substrate is longer than the second die lip by 100 μm or more and 300 μm or less.

8. the pair of guide lips and the second die lip each protrude toward the substrate with a predetermined thickness, The slot die coater according to claim 6 , wherein the pair of guide lips are configured to be thicker than the second die lip.

9. The second die includes: a second die lip protruding from between the pair of guide lips toward the substrate and forming the other side wall of the opening; The slot die coater according to claim 5 , wherein the first die lip is configured to protrude toward the substrate in a longer shape than the second die lip.

10. The first die block comprises: a first support protrusion protruding from one side surface of the first die block facing the second die block toward the second die block; a second support protrusion protruding from the other side surface of the first die block facing the third die block toward the third die block, The second die block comprises: a first support groove configured to receive the first support protrusion and support the first die block; The third die block comprises: The slot die coater of claim 1 , further comprising a second support groove configured to receive the second support protrusion and support the first die block.

11. An electrode coating apparatus comprising the slot die coater according to any one of claims 1 to 10, wherein the slot die coater is used to coat an electrode substrate.

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