Double slot die coater

Abstract

A double-slit die coater is provided that can easily adjust a coating gap and control a widthwise deviation of the coating gap. The double-slit die coater includes a first slit and a second slit for discharging a coating solution in a direction opposite to gravity. The double-slit die coater includes: a first die block vertically mounted at the rear of an upper surface of a base; a second die block disposed at the front surface of the first die block to form a first slit between the second die block and the first die block; a third die block disposed at the front surface of the second die block to form a second slit between the third die block and the second die block; and an alignment block disposed between the front of the upper surface of the base and the lower surface of the second die block and fastened to the lower surface of the second die block by bolts.

Description

Technical Field

[0001] The present disclosure relates to a double slot die coater capable of simultaneously forming two or more layers in a wet process, and in particular to a double slot die coater having a device for controlling a widthwise deviation of a coating gap.

[0002] This application claims priority to Korean Patent Application No. 10-2020-0185693 filed in Korea on December 29, 2020, the disclosure of which is incorporated herein by reference. Background Art

[0003] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as energy sources is rapidly increasing, and such secondary batteries essentially include an electrode assembly as a power generation element. The electrode assembly has a form in which a positive electrode, a separator, and a negative electrode are stacked at least once, and the positive electrode and the negative electrode are prepared by applying and drying a positive electrode active material slurry and a negative electrode active material slurry on a current collector made of aluminum foil and copper foil, respectively. In order to equalize the charge and discharge characteristics of the secondary battery, it is necessary to evenly coat the positive electrode active material slurry and the negative electrode active material slurry on the current collector, and for this purpose, a slit die coater is generally used.

[0004] Figure 1 is a cross-sectional view of a conventional slot die coater.

[0005] Reference Figure 1 In the electrode manufacturing method using the slot die coater, the active material slurry discharged from the slot die coater 30 is coated on the current collector 20 conveyed by the coating roller 10. The active material slurry discharged from the slot die coater 30 is widely coated on one surface of the current collector 20 to form an active material layer. The slot die coater 30 includes two mold blocks 31 and 32 and a single slot 35 is formed between the two mold blocks 31 and 32, and one type of active material slurry can be discharged through a discharge port 37 connected to the single slot 35 to form an active material layer of one layer. The slot die coater can achieve fast coating compared to bar coating or comma coating, and thus has been widely used in terms of high productivity. Figure 1 The slot die coater illustrated in is a vertical die type that discharges the active material slurry in a direction opposite to gravity.

[0006] In order to manufacture high energy density secondary batteries, the thickness of the active material layer of about 130μm is gradually increased to 300μm. When a thick active material layer is formed with a conventional slot die coater 30, the final electrode is not uniformly manufactured due to the migration of the binder and conductive material in the active material slurry during the drying process. To solve this problem, it takes a long time to perform two coatings, such as applying a thin layer of active material and drying it, and then applying the active material layer again and drying it. In order to improve both electrode performance and productivity, a double slot die coater that can simultaneously apply two types of electrode active material slurries is required.

[0007] Since slot die coaters form slots on the coupling surfaces of the mold blocks, three mold blocks, each including two slots, are generally required, as in a double-slot die coater. Since processes using a double-slot die coater require active material slurries to be simultaneously discharged from different discharge ports, it is difficult to form each active material layer to the desired thickness.

[0008] The spacing distance from the discharge port to the surface of the current collector is the coating gap, which is a very important variable that determines the coating quality of the active material layer. In general, the thickness of each active material layer is affected by the amount of each active material slurry discharged from the discharge port, the type of active material slurry, and the coating gap. When the coating gap is uniform in the width direction of the current collector (transverse direction (TD)), stable coating can be performed, while when there is a coating gap deviation in the width direction, the coating width and the shape of the boundary of the uncoated part are greatly affected. The thickness of the active material layer is a very small value of tens to hundreds of microns and should be controlled very strictly because even a thickness change of only a few microns can seriously affect the coating quality. In order to stably and uniformly coat the current collector in the width direction, it is necessary to strictly control the thickness of the active material layer to show uniform dimensional accuracy in the width direction. However, when the width of the double-slit die coater is increased to increase the output using a wide current collector, uniform coating in the width direction becomes more difficult, and precise control of the coating gap becomes more necessary.

[0009] In addition, an appropriate coating gap range is determined according to the type of active material slurry. During the production process, it is necessary to use multiple types of active material slurries instead of one type of active material slurry to manufacture various products. In order to use multiple active material slurries, it is difficult to provide a double-slit die coater dedicated to each active material slurry separately. Therefore, it is necessary to first coat a certain type of active material slurry with a double-slit die coater, and then coat another type of active material slurry with a double-slit die coater. In this case, it is necessary to change the pre-set coating gap. In addition, it is difficult to always coat the same type of active material slurry uniformly because there is dispersion of the active material slurry due to physical properties depending on the manufacturing time point, and therefore it is necessary to deal with this dispersion. In addition, coating gap control becomes more important because rapid coating reveals huge coating quality variations due to the dispersion of the active material slurry.

[0010] In the prior art, to create the desired coating gap, it was necessary to repeatedly disassemble and reassemble each mold block, while experimentally performing multiple coating processes to adjust and check the coating gap. However, the coating gap is a variable that can be sensitively adjusted and varied, not only by the tightening strength of the bolts used to assemble the mold blocks, but also by the discharge force of the active material slurry.

[0011] To construct an apparatus with a footprint and volume similar to that of a conventional slot die coater 30 comprising a single slot, each die block must be thin, inevitably leading to structural deformation and distortion. This deformation or distortion can cause the carefully adjusted coating gap to become distorted, a serious problem that can lead to defects in electrode processing. Summary of the Invention

[0012] Technical issues

[0013] The present disclosure is designed to solve the problems of the prior art, and thus the present disclosure provides a double-slot die coater capable of easily adjusting a coating gap and controlling a widthwise deviation of the coating gap.

[0014] These and other purposes and advantages of the present disclosure can be understood from the following detailed description and will become more apparent through the exemplary embodiments of the present disclosure. In addition, it is easy to understand that the purposes and advantages of the present disclosure can be achieved by the modes shown in the appended claims and their combinations.

[0015] Technical Solution

[0016] In one aspect of the present disclosure, there is provided a double-slot die coater including a first slit and a second slit for discharging a coating solution in a direction opposite to gravity, the double-slot die coater including: a first mold block vertically mounted at the rear of an upper surface of a base; a second mold block disposed at the front surface of the first mold block to form a first slit between the second mold block and the first mold block; a third mold block disposed at the front surface of the second mold block to form a second slit between the third mold block and the second mold block; and an alignment block disposed between the front of the upper surface of the base and the lower surface of the second mold block and fastened to the lower surface of the second mold block by bolts.

[0017] In an embodiment of the present disclosure, the base and the first mold block are integrated with each other.

[0018] The first slit may be perpendicular to the base.

[0019] The second mold block may have a right triangle cross-section.

[0020] A vertical length of each of the second and third mold blocks may be smaller than a vertical length of the first mold block.

[0021] The alignment block may include a step portion located at a front portion of an upper surface of the base and a front surface of the base.

[0022] The bolts may include bolts fastened to the alignment block and the second mold block through a lower surface of the base, and bolts fastened to the third mold block through the alignment block.

[0023] The bolts may also include bolts that pass through the front surface of the alignment block and are fastened to the base.

[0024] A lower surface of the second mold block and a lower surface of the third mold block may closely contact an upper surface of the alignment block and may be aligned with each other.

[0025] The first, second, and third mold blocks may include first, second, and third mold lips as respective front end portions, and the first, second, and third mold lips may be located on the same straight line.

[0026] A first discharge port communicating with the first slit may be formed between the first die lip and the second die lip, a second discharge port communicating with the second slit may be formed between the second die lip and the third die lip, the double-slit die coater may extrude and coat the active material slurry on the surface of a continuously traveling substrate through at least one of the first slit and the second slit, and a step may be formed between the first discharge port and the second discharge port.

[0027] The alignment block may be provided in plural in the width direction of the double slot die coater.

[0028] The vertical cross section of the alignment block may include a first cross section portion and a second cross section portion extending vertically from the first cross section portion. In other words, the vertical cross section may have Or "L" shape.

[0029] The alignment block may be a single unitary component, rather than being divided into multiple components.

[0030] Beneficial effects

[0031] According to the present disclosure, the lower surfaces of the mold blocks are aligned with each other via the alignment blocks. The lower surfaces of the mold blocks can be naturally aligned with each other by the engagement of the mold blocks with the alignment blocks. This prevents misalignment between the mold blocks, and the distance between the front ends of the mold blocks and the substrate, i.e., the coating gap, can be consistently maintained at a desired level. Because the mold blocks are secured via the alignment blocks, the established coating gap is not easily altered during the process and is maintained, thereby suppressing variations in the coating gap widthwise.

[0032] Therefore, according to the present disclosure, there is no need to adjust the coating gap when disassembling and reassembling the mold block, which is structurally fragile due to its thin thickness. Instead, a constant coating gap can be always maintained by simply coupling the mold block to the alignment block. The alignment block reliably controls the uniform widthwise gap through the large surface contact of the blocks.

[0033] According to the present disclosure, even when deformation of the mold block due to the discharge pressure of the active material slurry is taken into account, the coating amount and coating quality can be uniformly controlled by maintaining a uniform coating gap (±2%). Therefore, a double-slot die coater with a uniform coating gap can be used to obtain uniform quality coated products, especially electrodes for secondary batteries.

[0034] As described above, according to the present disclosure, even when the discharge pressure of the active material slurry is increased and a thin die block is used, the effect of maintaining the adjusted coating gap is good. This has the effect of ensuring coating processability and ensuring reproducibility.

[0035] Using such a double slot die coater, a coating layer, particularly an active material layer, can be uniformly formed to a desired thickness. Preferably, two types of active material slurries can be coated simultaneously, thereby achieving excellent performance and productivity.

[0036] According to the present disclosure, multiple alignment blocks can be provided across the width of a double-slit die coater. This allows for precise control without causing coating gap deviation across the width. Consequently, even on wide current collectors, uniform dimensional accuracy can be achieved, ensuring stable and uniform coating across the width.

[0037] The appropriate coating gap range can be determined based on the type of active material slurry. In the present disclosure, multiple types of alignment blocks with appropriate thicknesses are prepared, and the process is performed by replacing the alignment blocks required for the production process. Therefore, even without a dedicated double-slot die coater for each active material slurry, a universal double-slot die coater can be used to process a variety of active material slurries. Furthermore, even if there is dispersion in the active material slurry, the coating gap can be adjusted by simply replacing the alignment blocks immediately to quickly address such dispersion.

[0038] As described above, when the double slot die coater of the present disclosure is used to manufacture electrodes for secondary batteries by coating active material slurry on a current collector while allowing the current collector to travel, it can have the advantage of uniform coating even under high-speed travel or wide-width coating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not limited to the accompanying drawings.

[0040] Figure 1 is a schematic cross-sectional view of a conventional slot die coater.

[0041] Figure 2 is a schematic cross-sectional view of a double slot die coater according to an embodiment of the present disclosure.

[0042] Figure 3 is included in Figure 2 A perspective view of the alignment block in a double slot die coater.

[0043] Figure 4 is a plan view of the lower surface of a double slot die coater according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms to obtain the best interpretation. Therefore, the descriptions presented herein are only preferred examples and are only used for illustrative purposes and are not intended to limit the scope of the present disclosure. Therefore, it should be understood that other equivalent replacements and modifications may be made thereto without departing from the scope of the present disclosure.

[0045] The double-slit die coater according to an embodiment of the present disclosure is a device comprising a first slit and a second slit to discharge a coating solution in a direction opposite to gravity and to coat a double layer on a substrate with the coating solution. The "substrate" described below is a current collector, and the coating solution is an "active material slurry". The first coating solution and the second coating solution are both active material slurries, which may refer to active material slurries having the same or different compositions (types of active materials, conductive materials, and binders), contents (amounts of each of active materials, conductive materials, and binders), or physical properties. The double-slit die coater according to an embodiment of the present disclosure is optimized for electrodes manufactured by simultaneously applying at least two types of electrode active material slurries or alternately applying at least two types of electrode active material slurries for patterned coating. However, the scope of the present disclosure is not necessarily limited thereto. For example, the substrate may be a porous support constituting a separation membrane, and the first coating solution and the second coating solution may be organic substances having different compositions or physical properties. That is, when thin film coating is required, any substrate, any first coating solution, and any second coating solution are all possible.

[0046] Figure 2 is a schematic cross-sectional view of a double slot die coater according to an embodiment of the present disclosure. Figure 3 is included in Figure 2 A perspective view of the alignment block in a double slot die coater. Figure 4 is a plan view of the lower surface of a double slot die coater according to an embodiment of the present disclosure.

[0047] The double slot die coater 100 according to an embodiment of the present disclosure is an apparatus including a first slot 101 and a second slot 102 and capable of coating two same or different types of coating solutions on a substrate 300 simultaneously or alternately through the first slot 101 and the second slot 102. Figure 2 As shown, the double slot die coater 100 includes a base A, a first mold block 110 , a second mold block 120 and a third mold block 130 .

[0048] exist Figure 2 In FIG. 1 , the double slot die coater 100 is installed to discharge active material slurry as a coating solution in a substantially vertical direction (X direction) (approximately: ±5 degrees).

[0049] As shown in the figure, the base A can be regarded as a rectangular parallelepiped having a predetermined length in the left-right direction and extending in the direction perpendicular to the paper surface (Z direction). The first mold block 110 is vertically installed at the rear of the upper surface of the base A. Preferably, the base A and the first mold block 110 are formed integrally with each other. The first mold block 110 has a plate-like structure, wherein the direction perpendicular to the paper surface (Z direction) is the width direction, and the first mold block 110 extends along the width direction. The first mold block 110 is placed on the base A and assembled with the base A. When the base A and the first mold block 110 are formed integrally in this manner, there is no need to align them relative to the base A, and the base A and the first mold block 110 can be handled as a whole, so it is easy to handle.

[0050] The second mold block 120 is located in the middle of the multiple mold blocks that make up the double-slot die coater 100. It is positioned between the first mold block 110 and the third mold block 130 to form the double slits. In this embodiment, the cross-section of the second mold block 120 is a right triangle, but this shape is not limited to this. For example, the cross-section can be an isosceles triangle.

[0051] The second mold block 120 is disposed on the front surface of the first mold block 110. The second mold block 120 has a plate-like structure, with the direction perpendicular to the paper (Z direction) being the width direction, and the second mold block 120 extends along the width direction. The first surface 120a of the second mold block 120, which faces the first mold block 110, is substantially perpendicular to the base A. In other words, the first surface 120a of the second mold block 120 is a vertical surface. The second surface 110b of the first mold block 110, which faces the first surface 120a of the second mold block 120, and the first surface 110a opposite to the second surface 110b (i.e., the rear surface forming the outer peripheral surface of the double-slit die coater 100) are also substantially perpendicular to the base A. In other words, the first surface 110a and the second surface 110b of the first mold block 110 are perpendicular surfaces. As a result, the first surface 120a of the second mold block 120 is substantially parallel to the first surface 110a and the second surface 110b of the first mold block 110. In the first mold block 110 , an inclined surface 110 a ′ inclined forward is formed above the first surface 110 a , so that the cross section of the upper portion of the first mold block 110 is approximately triangular.

[0052] The third mold block 130 is arranged on the front surface of the second mold block 120. The third mold block 130 also has a plate-like structure, in which the direction perpendicular to the paper surface (Z direction) is the width direction, and the third mold block 130 extends along the width direction. The second surface 120b of the second mold block 120 facing the third mold block 130, the first surface 130a of the third mold block 130 facing the second surface 120b of the second mold block 120, and the second surface 130b opposite to the first surface 130a (that is, the front surface forming the outer peripheral surface of the double-slit die coater 100) are almost parallel to each other. In the third mold block 130, an inclined surface 130b' inclined backward is formed above the second surface 130b. The cross-section of the upper part of the third mold block 130 is also roughly triangular. The surface 130b" below the second surface 130b of the third mold block 130 is almost perpendicular to the base A. In other words, the surface 130b" is also a vertical surface.

[0053] The surfaces of first, second, and third mold blocks 110, 120, and 130, which are opposite to the active material slurry discharge direction, i.e., lower surfaces 110c, 120c, and 130c, are nearly horizontal (Y direction). In such mold blocks 110, 120, and 130, since the corners formed by the surfaces have right-angled portions, right-angled portions exist in cross-section, and since a vertical or horizontal surface is used as a reference surface, mold blocks 110, 120, and 130 are easy to manufacture or handle, and their accuracy is guaranteed.

[0054] First mold block 110 , second mold block 120 , and third mold block 130 are not necessarily limited to the shapes in the above examples, and may be configured as horizontal molds, for example, with the discharge direction of the active material slurry being horizontal and lower surfaces 110 c , 120 c , 130 c being rear surfaces.

[0055] Mold blocks 110, 120, and 130 are made of, for example, SUS. Easily machined materials such as SUS420J2, SUS630, SUS440C, SUS304, and SUS316L can be used. SUS has the advantages of being easy to machine, inexpensive, highly corrosion-resistant, and can be manufactured into desired shapes at low cost.

[0056] Among the die blocks constituting the double slot die coater 100, the first die block 110 is located Figure 2In the mold block on the right and rear side of the mold block, since the second surface 110b facing the second mold block 120 is perpendicular to the base A, the first slit 101 can be perpendicular to the base A. The first slit 101 can be formed where the first mold block 110 and the second mold block 120 face each other. The first slit 101 is formed by the combination of the first mold block 110 and the second mold block 120. For example, the first spacer 113 is inserted between the first mold block 110 and the second mold block 120 to provide a gap therebetween to form the first slit 101 corresponding to the channel through which the first coating solution 50 can flow. In this case, the thickness of the first spacer 113 determines the vertical width (slit gap) of the first slit 101.

[0057] First spacer 113 includes an opening portion with a cutout area and can be inserted into the remaining portion of the boundary region of the opposing surfaces of first mold block 110 and second mold block 120, except for one side. Therefore, first drain port 101a is formed only between the front end portion of first mold block 110 and the front end portion of second mold block 120, through which first coating solution 50 can be discharged to the outside. The front end portion of first mold block 110 and the front end portion of second mold block 120 are defined as first mold lip 111 and second mold lip 121, respectively. In other words, first drain port 101a can be formed by spacing first mold lip 111 and second mold lip 121 apart from each other. Each of first mold lip 111 and second mold lip 121 extends in the width direction and can be a rectangular parallelepiped with a flat upper surface.

[0058] For reference, the first spacer 113 serves as a gasket to prevent the first coating solution 50 from leaking into the gap between the first and second mold blocks 110 and 120 except for the region where the first discharge port 101a is formed, and is therefore preferably made of a material having sealing properties.

[0059] First mold block 110 includes a first manifold 112 having a predetermined depth on second surface 110b facing second mold block 120 and capable of communicating with first slit 101. First manifold 112 is a space provided from second surface 110b of first mold block 110 facing second mold block 120 toward first surface 110a opposite second surface 110b. First manifold 112 is connected to an externally mounted first coating solution supply chamber (not shown) via a supply pipe to receive first coating solution 50. When first coating solution 50 is filled in first manifold 112, it is guided along first slit 101 and discharged to the outside through first discharge port 101a.

[0060] Third mold block 130 is disposed in front of second mold block 120 and second slit 102 is formed between third mold block 130 and second mold block 120. Therefore, second slit 102 is formed between second mold block 120 and third mold block 130 facing each other. In other words, second slit 102 is formed by the combination of third mold block 130 and second mold block 120.

[0061] Similar to the first slit 101 described above, a second spacer 133 may be inserted between the second mold block 120 and the third mold block 130 to provide a gap therebetween. Thus, a second slit 102 is formed, corresponding to a passage through which the second coating solution 60 can flow. In this case, the second spacer 133 determines the vertical width (slit gap) of the second slit 102.

[0062] Furthermore, second spacer 133 also has a structure similar to first spacer 113 described above, including an open portion with a cutout area. It can be inserted into the boundary region between the opposing surfaces of second mold block 120 and third mold block 130, except for one side. Similarly, second spacer 133 is blocked circumferentially except for the front portion of second slit 102, and second drain port 102a is formed only between the front ends of second mold block 120 and third mold block 130. The front end of third mold block 130 is defined as third mold lip 131. In other words, second drain port 102a is formed by spacing second mold lip 121 and third mold lip 131 apart from each other. Third mold lip 131 also extends in the width direction and can be a rectangular parallelepiped with a flat upper surface.

[0063] Third mold block 130 includes a second manifold 132 having a predetermined depth on a first surface 130a facing second mold block 120 and communicating with second slit 102. Second manifold 132 is a space extending from first surface 130a toward a second surface 130b opposite first surface 130a. Although not shown in the drawings, second manifold 132 is connected to an externally mounted supply chamber for second coating solution 60 via a supply pipe to receive second coating solution 60. When second coating solution 60 is supplied from the outside along a tubular pipe and fills second manifold 132, it is guided along second slit 102 communicating with second manifold 132 and discharged to the outside through second discharge port 102a.

[0064] The second slit 102 and the first slit 101 form a certain angle, which can be about 20 degrees to 70 degrees. The second slit 102 and the first slit 101 can intersect at a point, and the second discharge port 102a and the first discharge port 101a can be arranged near the intersection. Therefore, the discharge points of the first coating solution 50 and the second coating solution 60 can be roughly concentrated at one point.

[0065] First manifold 112 and second manifold 132 are formed in first mold block 110 and third mold block 130, respectively. This can minimize deformation of second mold block 120, which is structurally the most fragile. Furthermore, when second mold block 120 is divided into a left mold block and a right mold block, the left mold block moves integrally with third mold block 130, and the right mold block moves integrally with first mold block 110. Second mold block 120 can be configured to slide at the interface between the left and right mold blocks, thereby facilitating changes in the positions of first slit 101 and second slit 102.

[0066] Angle θ between second surface 120b of second mold block 120 facing third mold block 130 and first surface 120a of second mold block 120 facing first mold block 110 is preferably determined within a range such that the active material slurry discharged from second discharge port 102a and the active material slurry discharged from first discharge port 101a do not form a vortex immediately after being discharged simultaneously. If angle θ is too small, second mold block 120 becomes too thin and easily deformed and distorted.

[0067] According to the double-slot die coater 100 having such a structure, the rotatably disposed coating roller 200 is located above the double-slot die coater 100. While the substrate 300 to be coated is driven by the rotating coating roller 200, the first coating solution 50 and the second coating solution 60 are continuously in contact with the surface of the substrate 300, so that the substrate 300 can be double-coated. Alternatively, the supply and interruption of the first coating solution 50 and the supply and interruption of the second coating solution 60 are alternately performed, thereby intermittently performing pattern coating on the substrate 300.

[0068] The double slot die coater 100 further includes an alignment block 140 that is fastened to lower surfaces 120 c and 130 c of the mold blocks 120 and 130 opposite to their front ends by bolts 141 and 142 to combine the two mold blocks 120 and 130. The alignment block 140 is disposed between the front portion of the upper surface of the base A and the lower surface 120 c of the second mold block 120.

[0069] Here, let's take the example of a case where the vertical length h1 of each of second mold block 120 and third mold block 130 is less than the vertical length h2 of first mold block 110. The vertical length represents the vertical distance from the bottom surface of each mold block to the mold lip. In this state, when the front end of second mold block 120 is aligned with the front end of first mold block 110, a space can be formed between lower surface 120c of second mold block 120 and the upper surface of base A. This space can be a space in which the upper surface is formed by lower surface 120c of second mold block 120, the lower surface is formed by the upper surface of base A, the front surface is open, the rear surface is formed by the front surface of first mold block 110, and the left and right sides are partially open.

[0070] The alignment block 140 is installed in the space. Specifically, the alignment block 140 may include a stepped portion 140' located at the front of the upper surface of the base A and the front surface of the base A. For example, the thickness D of the stepped portion 140' may correspond to the difference between the vertical length h1 of each of the second mold block 120 and the third mold block 130 and the vertical length h2 of the first mold block 110.

[0071] Bolt 141 passes through the lower surface of base A and is vertically fastened to alignment block 140 and second mold block 120. Bolt 142 passes through alignment block 140 and is vertically fastened to third mold block 130. Bolt 143 passes through the front surface of alignment block 140 and is horizontally fastened to base A. Bolts 141, 142, and 143 can be fastened in positions so that they do not interfere with each other. With this structure, lower surface 120c of second mold block 120 and lower surface 130c of third mold block 130 can contact and align with the upper surface of alignment block 140, and lower surface 120c of second mold block 120 and lower surface 130c of third mold block 130 can be stepped relative to lower surface 110c of first mold block 110.

[0072] like Figure 3As shown, the alignment block 140 has an upper surface 140a that contacts the lower surface 120c of the second mold block 120 and the lower surface 130c of the third mold block 130. Unlike the upper surface 140a, the lower surface 140b includes a step portion 140', and the thickness D of the step portion 140' is smaller than the thickness of the other parts. The step portion 140' has a structure that can be mounted on the front part of the upper surface of the base A and the front surface of the base A. In the alignment block 140, holes H through which bolts 141, 142 and 143 pass may be further formed to tighten the bolts 141, 142 and 143. The number of holes H and the positions of the holes H may be different from those shown in the figures. A vertical section of the alignment block 140 passing through the upper surface 140a, the lower surface 140b and the step portion 140' includes a first cross-sectional portion and a second cross-sectional portion extending vertically from the first cross-sectional portion. In other words, the vertical section has Or "L" shape. This makes the processing of simple blocks unnecessary and allows for precision machining. Similarly to mold blocks 110, 120, and 130, since the corners formed by the surfaces of alignment block 140 are right angles, a right-angle portion exists in the cross section, and since a vertical surface or a horizontal surface serves as a reference surface, alignment block 140 is easy to manufacture or process and its accuracy is ensured. When first mold block 110, second mold block 120, and third mold block 130 are combined and alignment block 140 is fastened to the combined body, their facing portions can support each other with large surface contact, thereby enabling fastening and fixation and good maintenance.

[0073] Double-slot die coaters are typically made of SUS. Because the joints of SUS components are prone to leakage, a rubber ring or other soft material is typically inserted between the components to create a seal and prevent leakage. However, this sealing method is not suitable for achieving uniform assembly shape (e.g., assembly deviations of less than 10 μm), making it difficult to apply to double-slot die coaters.

[0074] For this reason, in a double-slit die coater, it is necessary to assemble the die blocks, which are processed with very high precision (straightness, flatness ±5μm), by bolting. To prevent leakage, bolting is performed with a high pressure of approximately 200 to 350N. However, this high-pressure bolting causes a slight stress imbalance, which may cause the die block to deform, and the pressure of the coating solution supplied during coating may cause the die block to deform or twist. Or the alignment block 140 of "L" shaped cross section is a structure that can withstand such high pressure bolt connection.

[0075] The alignment block 140 can be a single, unitary component, rather than being divided into multiple parts. In other words, the alignment block 140 is a one-piece, seamless component. This not only improves the accuracy of the alignment block 140 during assembly, but also provides a strong structure for the alignment block 140, thus providing excellent stability against external impacts during handling and use.

[0076] According to this embodiment, alignment block 140 joins third mold block 130 and second mold block 120 together. Because lower surface 130c of third mold block 130 is parallel to lower surface 120c of second mold block 120, when vertical lengths h1 of second mold block 120 and third mold block 130 are identical, third mold lip 131 and second mold lip 121, which serve as the leading ends of mold blocks 130 and 120, respectively, can be aligned. In other words, third mold lip 131 and second mold lip 121 can be positioned at the same height from base A, and the lower circumferential surface of coating roller 200 can be positioned above third mold lip 131 and second mold lip 121 with a certain coating gap. Thus, alignment block 140 determines the position of third mold lip 131 and second mold lip 121, thereby influencing the coating gap.

[0077] Reference Figure 4 , a plurality of alignment blocks 140 may be arranged in the width direction of the double slot die coater 100. The alignment blocks 140 reliably control a uniform width direction gap through large surface contact of the blocks.

[0078] Due to the structure of alignment block 140, third mold block 130 and second mold block 120 are combined and move as a single unit, allowing the relative positions of second discharge port 102a and first discharge port 101a to be adjusted. The degree of position adjustment varies depending on the thickness D of stepped portion 140' of alignment block 140, and the coating gap is determined accordingly. Furthermore, positional misalignment between mold blocks 110, 120, and 130 can be prevented. Compared to the prior art, combining mold blocks 130, 120 with alignment block 140 makes it easier to determine the coating gap. This eliminates the inconvenience of adjusting the coating gap when disassembling and adjusting the positions of mold blocks 130, 120, and 110, and improves assembly accuracy.

[0079] In this embodiment, an example is shown in which the vertical length h1 of the third mold block 130 (the vertical distance from the lower surface 130c to the third mold lip 131) and the vertical length of the second mold block 120 (the vertical distance from the lower surface 120c to the second mold lip 121) are smaller than the vertical length h2 of the first mold block 110 (the vertical distance from the lower surface 110c to the first mold lip 111). In this state, when the alignment block 140, which includes a stepped portion 140' having a thickness D corresponding to the difference between the vertical lengths h1 and h2, is secured to the third and second mold blocks 130 and 120, the first, second, and third mold lips 111, 121, and 131 can also be positioned on the same straight line. In this case, the entire double-slot die coater 100 can coat various layers while moving forward or backward relative to the substrate 300.

[0080] If the vertical length of each of third mold block 130 and second mold block 120 is equal to the vertical length of first mold block 110, tightening alignment block 140 can cause second mold lip 121 and third mold lip 131 to protrude further toward substrate 300 than first mold lip 111. At this time, a step is formed between first discharge port 101a and second discharge port 102a. When the step is formed between first discharge port 101a and second discharge port 102a and first discharge port 101a and second discharge port 102a are vertically spaced apart, second coating solution 60 discharged from second discharge port 102a does not transfer to first discharge port 101a, and first coating solution 50 discharged from first discharge port 101a does not transfer to second discharge port 102a. In other words, the coating solution discharged through first discharge port 101a or second discharge port 102a is blocked by the surface of the step formed between first discharge port 101a and second discharge port 102a, eliminating the risk of the coating solution flowing into the other discharge port. Therefore, a smoother multi-layer active material coating process can be performed.

[0081] By such fastening of the alignment block 140, the distance between the third mold lip 131, the second mold lip 121, and the first mold lip 111, which are the front end portions of the respective mold blocks 130, 120, and 110, and the substrate 300, i.e., the coating gap, can always be maintained at a desired level, and the mold blocks 130 and 120 are fixed to each other, thereby maintaining the determined coating gap without change during the process.

[0082] Therefore, there is no need to adjust the coating gap when disassembling and reassembling the mold blocks 130 , 120 and 110 , which are structurally fragile due to their small thickness, and a constant coating gap can be always maintained by a simple operation of coupling the mold blocks 130 and 120 to the alignment block 140 .

[0083] According to the present disclosure, even when deformation of the mold block due to the discharge pressure of the active material slurry is taken into account, the coating amount and coating quality can be uniformly controlled by maintaining a uniform coating gap (±2%). Therefore, a double-slot die coater with a uniform coating gap can be used to obtain uniform quality coated products, especially electrodes for secondary batteries.

[0084] As described above, according to the present disclosure, even if the discharge pressure of the active material slurry increases, the effect of maintaining the adjusted coating gap is excellent, which has the effects of ensuring coating processability and ensuring reproducibility.

[0085] Using such a double slot die coater, a coating layer, particularly an active material layer, can be uniformly formed to a desired thickness. Preferably, two types of active material slurries can be coated simultaneously, thereby achieving excellent performance and productivity.

[0086] In particular, including the plurality of alignment blocks 140 in the width direction of the double slot die coater 100 enables precise control without coating gap deviation even in the width direction.

[0087] The appropriate coating gap range is determined based on the type of active material slurry. In the present disclosure, multiple types of alignment blocks with stepped portions of appropriate thickness are prepared, and each production process is performed by replacing the alignment blocks required. Therefore, even when a dedicated double-slot die coater for each active material slurry is not available, the double-slot die coater can be used universally to handle a variety of active material slurries. Furthermore, even if there is dispersion in the active material slurry, this dispersion can be quickly addressed by simply replacing the alignment blocks.

[0088] As described above, when the double slot die coater of the present disclosure is used to coat active material slurry on a current collector while allowing the current collector to travel to manufacture an electrode for a secondary battery, it has the advantage of achieving uniform coating even under high-speed travel or wide-width coating conditions.

[0089] In this embodiment, the case where the coating solution is applied in two layers or the case where the coating solution is alternately supplied for pattern coating is described as an example. However, the present disclosure is applicable to the case where three or more slits are provided to simultaneously coat three or more layers.

[0090] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, as various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from the detailed description.

[0091] At the same time, although terms indicating directions such as up, down, left, and right are used in this specification, these terms are only for convenience of description, and it is obvious to those skilled in the art that these terms can change depending on the position of the target object or the position of the observer.

Claims

1. A double slot die coater comprising a first slot and a second slot for discharging a coating solution in a direction opposite to gravity, the double slot die coater comprising: a first mold block vertically mounted on a rear portion of the upper surface of the base; a second mold block disposed on a front surface of the first mold block to form the first slit between the second mold block and the first mold block; a third mold block disposed on a front surface of the second mold block to form the second slit between the third mold block and the second mold block; and an alignment block disposed between a front portion of the upper surface of the base and a lower surface of the second mold block and fastened to the lower surface of the second mold block by bolts, wherein the alignment block includes a step portion located at a front portion of an upper surface of the base and a front surface of the base, and The bolts include bolts passing through the lower surface of the base and fastened to the alignment block and the second mold block, and bolts passing through the alignment block and fastened to the third mold block.

2. The double-slit die coater according to claim 1, wherein: The base and the first mold block are integrated with each other.

3. The double slot die coater according to claim 1, wherein: The first slit is perpendicular to the base.

4. The double slot die coater according to claim 1, wherein: The cross section of the second mold block is a right triangle.

5. The double slot die coater according to claim 1, wherein: A vertical length of each of the second mold block and the third mold block is smaller than a vertical length of the first mold block.

6. The double slot die coater according to claim 1, wherein: The bolt includes a bolt that passes through a front surface of the alignment block and is fastened to the base.

7. The double slot die coater according to claim 1, wherein: A lower surface of the second mold block and a lower surface of the third mold block closely contact an upper surface of the alignment block and are aligned with each other.

8. The double slot die coater according to claim 1, wherein: The first mold block, the second mold block, and the third mold block respectively include a first mold lip, a second mold lip, and a third mold lip as respective front end portions, and the first mold lip, the second mold lip, and the third mold lip are located on the same straight line.

9. The double slot die coater according to claim 1, wherein: The first mold block, the second mold block, and the third mold block respectively include a first mold lip, a second mold lip, and a third mold lip as their respective front end portions, A first discharge port communicating with the first slit is formed between the first mold lip and the second mold lip, and a second discharge port communicating with the second slit is formed between the second mold lip and the third mold lip. The double-slit die coater extrude and coat the active material slurry on the surface of the continuously traveling substrate through at least one of the first slit and the second slit, A step is formed between the first discharge port and the second discharge port.

10. The double slot die coater according to claim 1, wherein: The alignment block is provided in plural in a width direction of the double-slit die coater.

11. The double slot die coater according to claim 1, wherein: A vertical cross-section of the alignment block includes a first cross-sectional portion and a second cross-sectional portion extending perpendicularly from the first cross-sectional portion.

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