Slot die coater

Abstract

A slot die coater according to the present invention is a slot die coater having a slot for ejecting a coating solution, in the direction opposite to gravity, onto the surface of a substrate continuously driven and transferred by a coating roll, the slot die coater comprising a first die block and a second die block which form the slot therebetween, wherein the center of the rotation axis of the coating roll is located closer to the second die block than the upper part of a first die lip forming the front end part of the first die block with respect to the substrate.

Description

Slot die coater

[0001] The present invention relates to a slot die coater, and more particularly, to a vertical die type slot die coater in which a coating liquid is discharged in a direction opposite to gravity. This application claims priority to Korean Patent Application No. 10-2024-0004388, filed January 10, 2024, and Korean Patent Application No. 10-2024-0079909, filed June 19, 2024, the entire contents of which are disclosed in the specification and drawings of the respective applications are incorporated herein by reference.

[0002] Secondary batteries, which boast high electrical properties such as high energy density and easy applicability across a wide range of product categories, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electrical power sources. These batteries are attracting attention as a new energy source for environmental friendliness and energy efficiency, not only for their primary advantage of dramatically reducing fossil fuel use, but also because they produce no byproducts from energy use.

[0003] These secondary batteries essentially contain an electrode assembly, which is a power generation element. The electrode assembly has a form in which a positive electrode, a separator, and a negative electrode are laminated at least once, and the positive and negative electrodes are manufactured by coating 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 ensure uniform charge and discharge characteristics of the secondary battery, the positive electrode active material slurry and the negative electrode active material slurry must be evenly coated on the current collector, and a slot die coater has been used conventionally.

[0004] Fig. 1 is a cross-sectional view showing a conventional slot die coater.

[0005] Referring to Fig. 1, in a conventional electrode manufacturing method using a slot die coater (1), an electrode active material slurry discharged from the slot die coater (1) is applied onto a current collector (3) conveyed by a coating roll (2). The electrode active material slurry discharged from the slot die coater (1) is widely applied to one surface of the current collector (3) to form an active material layer. The slot die coater (1) includes two die blocks (4, 5) and has a slot (6) formed between the two die blocks (4, 5), and one type of electrode active material slurry can be discharged through a discharge port (7) communicated with the slot (6) to form one active material layer. The slot die coater (1) has the advantage of high-speed coating compared to bar coating or comma coating, and is widely applied from the viewpoint of high productivity. The slot die coater (1) as an example in Fig. 1 is a vertical die type in which the electrode active material slurry is discharged in a direction opposite to gravity.

[0006] In order to manufacture high-energy-density secondary batteries, the thickness of the active material layer, which was about 130㎛, is gradually increasing to reach 300㎛. When a thick active material layer is formed using a conventional slot die coater (1), migration of the binder and conductive agent in the electrode active material slurry becomes severe during drying, resulting in an uneven final electrode. If this problem is solved by coating twice, such as applying a thin layer of active material, drying it, and then applying it again on top and drying it, it takes a long time. In order to improve both electrode performance and productivity, a dual slot die coater with two slots is required so that two types of electrode active material slurry can be applied simultaneously to coat in a double layer of upper and lower layers.

[0007] Since a slot die coater forms slots on the mating surfaces of die blocks, three die blocks are basically required to have two slots, as in a dual slot die coater. Processes utilizing such a dual slot die coater require the use of electrode active material slurries that are simultaneously discharged from different discharge ports connected to each of the two slots, making it quite difficult to form each active material layer to a desired thickness.

[0008] In addition, the distance from the discharge port (7) to the surface of the current collector (3) is a coating gap, which is a very important variable in determining the coating quality of the active material layer. In general, the thickness of the active material layer is affected by the discharge amount of the electrode active material slurry through the discharge port (7), the type of the electrode active material slurry, and the coating gap. In addition, the coating gap must be uniform in the width direction of the current collector (TD direction) to enable stable coating, and if there is a deviation in the width direction of the coating gap, it greatly affects the coating width and the shape of the boundary of the uncoated region, etc. The thickness of the active material layer must be very strictly controlled because it has a serious impact on the coating quality even if it changes by only a few ㎛, and it needs to be very strictly controlled to exhibit uniform dimensional precision in the width direction in order to stably perform uniform coating in the width direction of the current collector.

[0009] However, as the width of the slot die coater (1) increases to use a wide current collector for increased production, it becomes more difficult to apply uniformly in the width direction, and thus precise control of the coating gap becomes more necessary. In addition, as illustrated in Fig. 1, the coating roll (2) has a curvature, and the current collector (3) placed thereon also has a curvature, so the coating gap changes depending on the position. Specifically, when the center of the coating roll (2) and the discharge port (7) are aligned in a line, the coating gap is minimum at the aligned position, and the coating gap increases as the distance from the aligned position increases.

[0010] In particular, coating processes using dual-slot die coaters require simultaneous application of electrode active material slurry from different outlets, making coating gap management even more critical. Furthermore, problems such as leaking and side rings are more serious than when forming a single layer. Leaking refers to the instability in which a portion of the coating solution leaks upstream from the die lip, which forms the leading edge of the die block. This results in the loss of pre-measured coating solution, making the final coating thickness unpredictable. This leakage can cause the coating solution to solidify due to prolonged retention, or can lead to variations in the widthwise coating thickness. This leakage can be exacerbated when the coating solution is discharged at high pressure with the coating gap reduced to several hundred micrometers for thin film coating or to reduce the widthwise thickness variation of the coating layer. The coating gap is thus closely related to leakage and must be precisely managed.

[0011] The present invention has been created in consideration of the above-described problems, and the problem to be solved by the present invention is to provide a slot die coater capable of precise control of a coating gap and suppressing the occurrence of leaking.

[0012] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0013] The slot die coater of the present invention for solving the above-described problem is a slot die coater having a slot for ejecting a coating liquid in a direction opposite to gravity onto a surface of a substrate continuously driven and conveyed by a coating roll, the slot die coater comprising: a first die block; and a second die block forming the slot between the first die block and the first die block, characterized in that the center of the rotational axis of the coating roll is positioned toward the second die block rather than the upper portion of the first die lip forming the leading end of the first die block with respect to the substrate.

[0014] The first die block is installed vertically as one piece with the base at the rear upper surface of the base, and the second die block is arranged on the front side of the first die block.

[0015] The second die block may not be in contact with the base, or may form a bending space between the base and the second die block even if it is in contact with the base.

[0016] A bending unit may be connected to the lower end of the above-mentioned base to deform the above-mentioned bending space.

[0017] A hole formed in the base to connect the bending unit and the base can be formed as a longitudinal hole in the front and rear directions to enable the position of the bending unit to be changed.

[0018] The center of the rotation axis of the above coating roll may be aligned with the bending center by the above bending unit.

[0019] The slot die coater of the present invention can be implemented not only as a device for coating a single layer, but also as a dual slot die coater, which is a device for coating a double layer. To this end, the dual slot die coater of the present invention may further include a third die block arranged on the front side of the second die block to form an additional slot between the second die block and the second die block.

[0020] In this case, the center of the rotation axis of the coating roll may be located in the middle of the first die lip, located at the lower portion of the first die lip, located at the upper portion of the second die lip forming the tip portion of the second die block, located in the middle of the second die lip, located at the lower portion of the second die lip, or located at the upper portion of the third die lip forming the tip portion of the third die block.

[0021] In particular, in a dual slot die coater, the second die block does not contact the base, or even if it does contact the base, forms a bending space between the base and the base, and a bending unit is connected to the lower end of the base to deform the bending space, and a hole formed in the base to fasten the bending unit and the base is formed as a longitudinal hole in the front-back direction, so that the center of the rotation axis of the coating roll can be aligned with the center of bending by the bending unit.

[0022] At this time, the above-mentioned hole may be formed to extend from behind the upper portion of the first die lip to in front of the lower portion of the third die lip.

[0023] Another slot die coater of the present invention for solving the above-described problem is a slot die coater having a slot for ejecting a coating liquid in a direction opposite to gravity on a surface of a substrate continuously driven and conveyed by a coating roll, the slot die coater comprising: a first die block vertically installed integrally with a base at a rear portion of an upper surface of the base; a second die block forming the slot between the first die block; and a bending unit connected to the lower end of the base, wherein when the center of rotation axis of the coating roll is changed with respect to the slot die coater, the bending center by the bending unit is also configured to move together.

[0024] The center of the rotation axis of the coating roll may be positioned toward the second die block rather than the upper portion of the first die lip forming the tip of the first die block with respect to the substrate.

[0025] By forming a hole in the base in a forward-backward direction to connect the bending unit and the base, it is possible to change the position of the bending unit.

[0026] The third die block may further include a third die block arranged on the front side of the second die block to form an additional slot between the third die block and the second die block.

[0027] The cross section of the above second die block may be a right triangle.

[0028] The first die block, the second die block and the third die block each have a first die lip, a second die lip and a third die lip forming a leading end of each die, and the center of the rotation axis of the coating roll is positioned toward the second die block with respect to the substrate rather than the upper portion of the first die lip, and the first die lip, the second die lip and the third die lip may be positioned on the same straight line, or the third die lip may be retracted relative to the first die lip or the second die lip.

[0029] For another example, the first die lip may be retracted relative to the second die lip or the third die lip, the second die lip may be retracted relative to the first die lip or the third die lip, or the third die lip may be advanced relative to the first die lip or the second die lip.

[0030] The thickness of the third die lip may be greater than the thickness of the first die lip and the thickness of the second die lip.

[0031] For another example, the thickness of the third die lip may be the same as the thickness of the first die lip and greater than the thickness of the second die lip.

[0032] According to the present invention, it is easy to adjust and maintain the distance between the die lip and the substrate, i.e., the coating gap, to a desired degree.

[0033] According to the present invention, the rotation axis center and bending center of the coating roll can be aligned with any part of the die lip of a vertical die type slot die coater.

[0034] According to the present invention, by forming a hole for connecting the bending unit and the base as a long hole, the bending center can also move when the vertical die alignment position is changed. According to the present invention, the rotational axis center of the coating roll and the bending center position can be easily changed and aligned, and the coating gap is maintained without change even during the process, so that the occurrence of a widthwise coating gap deviation perpendicular to the running direction of the substrate can be suppressed.

[0035] According to the present invention, the coating gap can be precisely maintained by taking into account the curvature of the coating roll. Furthermore, by maintaining a uniform (±2%) coating gap, the coating amount and resulting coating quality can be uniformly controlled. Therefore, using a slot die coater with a uniform coating gap, a coated product of uniform quality, particularly an electrode for a secondary battery, can be obtained.

[0036] According to the present invention, a slot die coater can be provided with space for bending. Bending deforms the area requiring alignment. According to the present invention, deformation is achieved with high uniformity even when using a bending unit for controlling widthwise coating uniformity. Thus, the present invention allows for highly uniform control of the deformation of die blocks, resulting in excellent coating uniformity, and the ease with which this can be achieved is a major advantage.

[0037] When the slot die coater of the present invention is used to manufacture electrodes of secondary batteries, etc. by applying electrode active material slurry on a current collector while driving the current collector, there is an advantage in that uniform application is possible even under high-speed driving or long-width application conditions.

[0038] In particular, according to the present invention, by moving the center of rotation axis of the coating roll toward the second die block rather than the upper part of the first die lip, the effect of preventing back leak during coating is excellent. In particular, when applied to a dual slot die coater, the coating gap between the upper and lower layers is made uniform, thereby ensuring individual loading quality of the upper and lower layers.

[0039] In addition, according to the present invention, the bending center can also be easily moved together, so that the center of rotation axis of the coating roll and the bending center can be moved toward the second die block rather than the upper part of the first die lip, so that the side of the pressurized portion where the bending force is applied by the bending unit can be made to have the smallest coating gap, thereby maintaining the bending effect (sensitivity).

[0040] In this way, by using the slot die coater according to the present invention, a coating layer, particularly an active material layer, can be uniformly formed to a desired thickness, and preferably, since simultaneous coating of two types of electrode active material slurries is possible, there is an excellent effect in both performance and productivity.

[0041] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0042] Figure 1 is a schematic cross-sectional view of a slot die coater according to the prior art.

[0043] FIG. 2 is a schematic cross-sectional view of a slot die coater according to one embodiment of the present invention.

[0044] Figure 3 is a schematic perspective view of the slot die coater of Figure 2.

[0045] Figure 4 is an exploded perspective view of Figure 3.

[0046] FIG. 5 illustrates another embodiment of a core that may be included in the slot die coater of FIG. 2.

[0047] Fig. 6 is a modified example of Fig. 3.

[0048] Figure 7 illustrates a hole for connecting a bending unit and a base included in the slot die coater of Figure 2.

[0049] FIG. 8 is a schematic cross-sectional view of a dual slot die coater according to another embodiment of the present invention.

[0050] Figures 9 and 10 are enlarged views of part A of Figure 8.

[0051] Fig. 11 is a schematic cross-sectional view of a dual slot die coater according to a comparative example.

[0052] Figure 12 is a graph simulating the coating gap by position when the center of the rotation axis of the coating roll is aligned with the upper part of the first die lip, as in a comparative example.

[0053] FIG. 13 is a graph simulating a coating gap by position when the center of the rotation axis of the coating roll is aligned with the lower part of the first die lip according to one embodiment of the present invention.

[0054] FIG. 14 is a graph simulating the coating gap by position when the center of the rotation axis of the coating roll is aligned with the upper part of the second die lip according to another embodiment of the present invention.

[0055] Figure 15 shows the results of a center and side loading test according to the bending level while changing only the rotation axis center alignment of the coating roll from the lower part of the first die lip to the upper part of the third die lip without moving the bending center.

[0056] Fig. 16 is a modified example of Fig. 8.

[0057] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of the term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0058] The slot die coater of the present invention is a device having one or two slots for discharging a coating liquid in a direction opposite to gravity, and coating a coating liquid on a substrate in a single layer or double layer. The 'substrate' described below is a current collector, and the 'coating liquid' is an electrode active material slurry. In the case of double-layer coating, both the first coating liquid and the second coating liquid are electrode active material slurries, and may refer to electrode active material slurries that are the same or different from each other in composition (type of active material, conductive material, and binder), content (amount of active material, conductive material, and binder), or physical properties. The slot die coater or dual slot die coater of the present invention is optimized for forming electrodes of secondary batteries. In particular, the dual slot die coater is optimized for manufacturing electrodes by simultaneously applying two types of electrode active material slurries or alternately applying two types of electrode active material slurries and pattern coating. However, the scope of the present invention is not necessarily limited thereto. For example, the substrate may be a porous support constituting a membrane, and the first and second coating solutions may be organic materials with different compositions and properties. In other words, if a thin film coating is required, the substrate, first and second coating solutions may be of any type.

[0059] Fig. 2 is a schematic cross-sectional view of a slot die coater according to one embodiment of the present invention. Fig. 3 is a schematic perspective view of the slot die coater of Fig. 2, and Fig. 4 is an exploded perspective view of Fig. 3. Fig. 5 illustrates another embodiment of a core that may be included in the slot die coater of Fig. 2. Fig. 6 is a modified example of Fig. 3. Fig. 2 may be a cross-sectional view taken along line II-II' of Fig. 3.

[0060] First, referring to FIGS. 2 and 3, the slot die coater (100) has one slot (115) and discharges electrode active material slurry through a discharge port (116) connected to the slot (115), thereby coating the electrode active material slurry on the surface of the substrate (60).

[0061] A slot die coater (100) is provided with a slot (115) for discharging a coating liquid, such as an electrode active material slurry, in a direction opposite to gravity onto the surface of a substrate (60) that is continuously transported by a coating roll (50). To this end, the slot die coater (100) includes a first die block (110) and a second die block (120). The second die block (120) forms a slot (115) between itself and the first die block (110).

[0062] The slot die coater (100) is installed so that the direction in which the coating liquid is discharged (X direction) is almost vertical (approximately: ± 5 degrees). In the embodiment of the present invention, the X-axis direction shown in the drawing refers to the direction in which the coating liquid is discharged, the Z-axis refers to the width direction or TD direction of the slot die coater (100), and the Y-axis direction refers to a horizontal direction that is perpendicular to both the X-axis direction and the Z-axis direction. In addition, the Y-axis direction refers to the front-back direction in the relationship between die blocks. In particular, the Y-axis direction refers to the direction from the first die block (110) toward the second die block (120). In this specification, the direction from the first die block (110) toward the second die block (120) is defined as the front, and conversely, the direction from the second die block (120) toward the first die block (110) is defined as the back.

[0063] The first die block (110) and the second die block (120) have a first die lip (112) and a second die lip (122), which form their respective ends with respect to the substrate (60). The Y-axis direction also means the up-down direction with respect to the die lips. The direction from the first die lip (112) toward the second die lip (122) is defined as downward, and conversely, the direction from the second die lip (122) toward the first die lip (112) is defined as upward.

[0064] The substrate (60) is transported by a coating roll (50), and the coating roll (50) can be positioned in the direction in which the coating liquid is discharged from the slot die coater (100). The slot die coater (100) can discharge the coating liquid in a direction opposite to gravity (X-axis direction), and can continuously or discontinuously coat the substrate (60) by discharging the coating liquid through the slot (115).

[0065] The coating roll (50) rotates about the rotation axis center (50_C). At this time, the rotation axis center (50_C) of the coating roll (50) is positioned closer to the second die block (120) than the upper portion (112a) of the first die lip (112) with respect to the substrate (60). Here, the upper portion (112a) of the first die lip (112) refers to the left side of the first die lip (112) in the drawing. For reference, the lower portion (112b) of the first die lip (112) refers to the right side of the first die lip (112) in the drawing. Here, the fact that the rotational axis center (50_C) of the coating roll (50) is positioned toward the second die block (120) rather than the upper portion (112a) of the first die lip (112) with respect to the substrate (60) indicates that the rotational axis center (50_C) of the coating roll (50) is positioned away from the upper portion (112a) of the first die lip (112) and toward the second die block (120) to further exceed the range of error that inevitably occurs when the rotational axis center (50_C) of the coating roll (50) is aligned evenly with the upper portion (112a) of the first die lip (112).

[0066] For example, even if the rotational axis center (50_C) of the coating roll (50) is aligned evenly with the upper portion (112a) of the first die lip (112), it can be aligned within a position about 50 ㎛ away from the front and rear. In the present invention, the rotational axis center (50_C) of the coating roll (50) can be positioned from a position about 100 ㎛ away from the upper portion (112a) of the first die lip (112) toward the lower portion (112b) of the first die lip (112) and further toward the second die block (120).

[0067] Preferably, the first die block (110) is vertically installed integrally with the base (105) at the rear portion of the upper surface (105a) of the base (105). Although the surface opposite to the direction in which the coating liquid is discharged from the first die block (110), i.e., the lower surface (110a), is illustrated in FIG. 2, if the first die block (110) and the base (105) are installed integrally, this lower surface (110a) may not be distinguished. The upper cross-section of the first die block (110) may be formed in a triangular shape. The first die block (110) has a plate-like structure extending in the width direction. The first die block (110) is placed against the base (105) and assembled. If the base (105) and the first die block (110) are integral in this way, there is no need for alignment with respect to the base (105) and they can be handled integrally, making handling convenient. The first die block (110) that is integral with the base (105) may be referred to as a body block. The XY cross-section of the first die block (110) can be viewed as roughly L-shaped.

[0068] At this time, the slot (115) may be perpendicular to the base (105).

[0069] The second die block (120) is placed on the front side of the first die block (110). The second die block (120) also has a plate-like structure extending along the width direction. The upper cross-section of the second die block (120) may also be formed in a triangular shape.

[0070] In the first die block (110) and the second die block (120), the surfaces opposite to the direction in which the coating liquid is ejected, that is, the lower surfaces (110a, 120a), are laid almost horizontally (YZ plane). Since these die blocks (110, 120) have parts where the edges formed by the surfaces are formed at right angles, a right-angled portion exists in the cross section, and a vertical or horizontal plane can be used as a reference surface, so that the manufacturing and handling are easy and the precision is guaranteed. In addition, when the first die block (110) and the second die block (120) are combined, the facing parts have a high degree of surface contact and can be supported by each other, so that the fastening, fixation, and maintenance are very excellent. In addition, the state in which the first die block (110) and the second die block (120) are combined has an overall roughly rectangular parallelepiped shape, and only the upper part from which the coating liquid is ejected has a shape that is slanted toward the substrate (60). The first die block (110) and the second die block (120) are made of, for example, SUS material. Materials that are easy to process, such as SUS420J2, SUS630, SUS440C, SUS304, and SUS316L, can be used. SUS has the advantages of being easy to process, inexpensive, having high corrosion resistance, and being able to be manufactured into a desired shape at low cost.

[0071] A shim (117) forming a slot (115) may be provided between the first die block (110) and the second die block (120). By providing a gap by the shim (117) between the first die block (110) and the second die block (120), a slot (115) corresponding to a passage through which a coating liquid can flow may be formed. In this case, the thickness of the shim (117) determines the upper and lower width (slot gap) of the slot (115).

[0072] As can be seen in Fig. 4, the core (117) may have at least one area cut to form an opening (117a). In this case, the core (117) may also have a plurality of openings (117a) in which the one area is intermittently cut, as shown in Fig. 5.

[0073] It is preferable that the core (117) be made of a material having sealing properties, as it also functions as a gasket to prevent the coating liquid from leaking into the gap between the first die block (110) and the second die block (120), except for the area where the discharge port (116) is formed.

[0074] Referring to FIG. 2, the first die block (110) may include a manifold (118) that receives a coating liquid and communicates with a slot (115). The manifold (118) may also be provided in the second die block (120). The manifold (118) may have a predetermined shape and depth. Although not shown in the drawing, the manifold (118) is connected to a coating liquid supply chamber (not shown) installed externally and a supply pipe to receive the coating liquid. When the coating liquid is filled in the manifold (118), the coating liquid is induced to flow along the slot (115) and discharged to the outside through the discharge port (116).

[0075] A shim (117) is provided between the first die block (110) and the second die block (120) to define the shape of the slot (115). The slot die coater (100) applies a coating liquid by discharging it onto a substrate (60) through an outlet (116) connected to the slot (115). The coating width of the coating layer coated on the substrate (60) is determined by the width of the slot (115). If a change in the coating width is required, the shim (117), which determines the internal space of the manifold (118) and the width of the slot (115), can be changed to implement various coating widths.

[0076] The core (117) is interposed in the remaining portion except for one side of the edge area of ​​the opposing surfaces of each of the first die block (110) and the second die block (120). For example, in order to form an active material layer with a coating width of a on the substrate (60) and to form non-coated regions on both sides of the active material layer, the width of the opening (117a) of the core (117) can be designed as a width of a, as in FIG. 4. The core (117) of FIG. 5 shows an example in which the width of the opening (117a) of the core (117) is designed as b, in order to form multiple active material layers with a coating width of b on the substrate (60) and to form non-coated regions on both sides of each active material layer. When such a core (117) is applied, a coating layer in the shape of a stripe pattern is formed on the substrate (60).

[0077] As illustrated in Fig. 2, the coating roll (50) can rotate clockwise around a horizontal rotation axis center (50_C). The substrate (60) can travel along its lower surface in a forward-backward direction (from right to left, i.e., from upstream to downstream).

[0078] The second die block (120) may not be in contact with the base (105) as in FIGS. 2 to 4, so that a bending space (S) may be formed between the lower surface of the second die block (120) and the upper surface of the base (105). Alternatively, even if the second die block (120) is in contact with the base (105) as in FIG. 6, a bending space (S) may be formed between the second die block (120) and the base (105).

[0079] In the examples shown in FIGS. 2 to 4, the second die block (120) is formed to be shorter in length than the first die block (110), so that the second die block (120) does not come into contact with the base (105), and a bending space (S) is formed between the lower surface (120a) of the second die block (120) and the upper surface (105a) of the base (105). If the length of the first die block (110) is L and the length of the second die block (120) is L', then L>L' is the relationship. This bending space (S) has an open front, a rear surface formed as the front of the first die block (110), and left and right sides in the width direction are open.

[0080] In the example shown in FIG. 6, the length L of the first die block (110) and the length L" of the second die block (120) are equal to each other. Instead, the lower surface (120a) of the second die block (120) has a rough structure so that the lower surface (120a) of the second die block (120) intermittently contacts the upper surface (105a) of the base (105). The length of the second die block (120) in the contacting portion may be L", and the length of the second die block (120) in the non-contacting portion may be L' (L"=L>L'). In the example shown in FIG. 6, the lower surface (120a) of the second die block (120) contacts the upper surface (105a) of the base (105), so that the force with which the base (105) supports the second die block (120) increases. In the part where the lower surface (120a) does not contact the upper surface (105a) of the base (105), a bending space (S) is provided. A stress relief effect due to this bending space (S) can be expected.

[0081] As shown in Fig. 4, the first die block (110) and the second die block (120) can be fastened by a coupling bolt (B). When the internal pressure of the die blocks (110, 120) increases due to the discharge of the coating liquid, a torque due to the internal pressure may be generated starting from the coupling bolt (B), and as a result, the part farthest from the coupling bolt (B) may receive the greatest force, causing a gap between the first die lip (112) and the second die lip (122). As shown in Fig. 6, if the lower surface (120a) of the second die block (120) is made to contact the upper surface (105a) of the base (105), even if a torque due to the internal pressure of the slot die coater (100) is generated, the contacting surfaces of the first die block (110) and the second die block (120) can support it.

[0082] And, looking at the assembly process of the die blocks, the lower surface (120a) of the second die block (120) is placed on the base (105) so as to be in contact with the upper surface (105a) of the base (105), and bolts (not shown) can be fastened from the lower side of the base (105) to the second die block (120) at each of the contacted positions. In this way, by fastening with bolts at the previously contacted positions and grinding the first die lip (112) and the second die lip (122) at the same time, there is also an effect that it is possible to align each die lip on the same straight line only by fastening the bolts at the contacted positions.

[0083] Referring to Fig. 2, a bending unit (140) can be connected to the lower end of the base (105). The bending unit (140) can be fastened to a hole (H) formed at the lower end of the base (105). The bending unit (140) can deform the bending space (S) by pressing the lower surface (105b) of the base (105).

[0084] The bending unit (140) may be provided with a die connection portion (142) that is fastened to the lower surface (105b) of the base (105) and presses the base (105). The die connection portion (142) may include a die connection portion (142a) and a main body connection portion (142b). If a hole (H) formed in the base (105) to fasten the bending unit (140) and the base (105) is formed as a longitudinal hole in the front-back direction, the position of the bending unit (140) can be changed in the front-back direction (see the two-way arrow) by changing the position of the die connection portion (142) connected thereto.

[0085] Since the bending effect changes depending on the change in the forward and backward direction of the rotational axis center (50_C) of the coating roll (50), it is preferable that the position of the bending center (142_C) also changes together with the rotational axis center (50_C) of the coating roll (50). The bending center (142_C) may refer to the center of the die connection portion (142). The bending center (142_C) may be located at the center portion in the width direction of the slot die coater (100).

[0086] As illustrated in Fig. 2, it is preferable that the rotational axis center (50_C) and the bending center (142_C) of the coating roll (50) be aligned with each other. Accordingly, the bending center (142_C) may coincide with the rotational axis center (50_C) of the coating roll (50) in the front-back direction of the slot die coater (100).

[0087] The bending unit (140) may include a servo motor (146) inside the main body (144). The servo motor (146) may be connected to a moving part (148) of the bending unit (140). The moving part (148) of the bending unit (140) is connected to a die connecting part (142). By the rotation of the servo motor (146), the moving part (148) may move in the X-axis direction and the -X-axis direction, and the die connecting part (142) connected thereto may press or pull the base (105) accordingly.

[0088] The side of the pressurized portion where the bending force is applied by the bending unit (140) can be made to have the smallest coating gap. The side of the pressurized portion is the bending center (142_C), and if this coincides with the center of rotation axis (50_C) of the coating roll (50), the bending effect (sensitivity) can be maintained.

[0089] In Fig. 2, the center of rotation axis (50_C) of the coating roll (50) is shown to be aligned with, for example, the lower portion (112b) of the first die lip (112) so as to move toward the second die block (120) rather than the upper portion (112a) of the first die lip (112).

[0090] When the center of rotation axis (50_C) of the coating roll (50) and the lower part (112b) of the first die lip (112) are aligned in a line, the coating gap is minimum at the alignment position, and the coating gap increases as it moves away from the alignment position, that is, in the front-back direction of the slot die coater (100).

[0091] The position of the bending unit (140) can be determined so that when a vertical line (Lc) from the rotation axis center (50_C) of the coating roll (50) passes through the lower part (112b) of the first die lip (112), the bending center (142_C) also passes through it. To this end, in the present invention, as detailed in Fig. 7, a hole (H) for connecting the bending unit (140) and the base (105) is formed as a long hole so that the bending center (142_C) can also move when the vertical die alignment position is changed.

[0092] Figure 7 illustrates a hole for connecting a bending unit and a base included in the slot die coater of Figure 2.

[0093] In an embodiment of the present invention, it is proposed to form a hole (H) for connecting a bending unit (140) and a base (105) as a long hole. The long hole is formed in a shape extending in the front-back direction. A die connecting part (142a) is connected to the hole (H) of the long hole, and a main body connecting part (142b) is connected thereto, so that the die connecting part (142) is connected to the base (105). When the die connecting part (142a) is connected to the hole (H) of the long hole, its position can be changed in the front-back direction, so that the die connecting part (142) connected thereto can be connected to different positions in the front-back direction.

[0094] That is, since the hole (H) for connecting the bending unit (140) and the base (105) is a long hole, the position of the bending unit (140) connected here can be moved. The position of the bending unit (140) can be located at the center part of the base (105) in the front-back direction, or can be placed closer to the second die block (120) than the first die block (120) as needed. The closer the part is to the bending unit (140), the greater the force it receives, and the greater the bending effect can be achieved. The bending unit (140) can push the base (105) toward the discharge direction or pull the base (105) in the opposite direction to the discharge direction. The bending unit (140) can bend the base (105) by pushing or pulling the base (105). The bending space (S) can be deformed. When the base (105) is bent, not only the first die block (110) formed integrally with the base (105), but also the second die block (120) connected to the first die block (110) by a bolt (B) can be bent simultaneously.

[0095] Preferably, the rotation axis center (50_C) of the coating roll (50) is moved toward the second die block (120) rather than the upper portion (112a) of the first die lip (112). For example, the rotation axis center (50_C) of the coating roll (50) is not aligned with the upper portion (112a) of the first die lip (112), but is changed to a lower portion, such as the middle portion of the first die lip (112), the lower portion (112b) of the first die block (110), or another location, such as toward the second die block (120). In addition, the bending center (142_C) is also changed to a position aligned therewith. Through this, a stable coating bead can be formed.

[0096] If the rotational axis center (50_C) of the coating roll (50) is aligned with the upper portion (112a) of the first die lip (112), the coating gap in the forward and backward direction of the slot die coater (100) may vary due to the curvature of the coating roll (50), which may have a serious effect on the coating quality. This will be described in detail later in the comparative example below.

[0097] Fig. 8 is a schematic cross-sectional view of a dual slot die coater according to another embodiment of the present invention. Figs. 9 and 10 are enlarged views of portion A of Fig. 8.

[0098] First, referring to FIG. 8, the dual slot die coater (200) has one more slot compared to the slot die coater (100) of FIG. 2.

[0099] To this end, the dual slot die coater (200) further includes a third die block (130) arranged in front of the second die block (120) to form an additional slot (125) between the second die block (120). For convenience, the slot (115) between the first die block (110) and the second die block (120) will be referred to as a first slot (115), and the additional slot (125) between the second die block (120) and the third die block (130) will be referred to as a second slot (125).

[0100] A dual slot die coater (200) can coat a surface of a continuously moving substrate (60) by extruding a coating liquid, such as an electrode active material slurry, through at least one of the first slot (115) and the second slot (125). The dual slot die coater (200) can discharge the coating liquid in a direction opposite to gravity, and can simultaneously or alternately coat the substrate (60) by discharging two types of coating liquids, the same or different, through the first slot (115) and the second slot (125).

[0101] In a dual slot die coater (200), the first die block (110) may be called an upper die, the second die block (120) may be called a middle die or inner die, and the third die block (130) may be called a lower die or outer die.

[0102] The second die block (120) of the present embodiment illustrated in Fig. 8 has a right-angled triangle cross-section, but is not necessarily limited to this shape, and for example, the cross-section may be formed as an isosceles triangle. When the cross-section is a right-angled triangle, the first slot (115) is aligned almost vertically with respect to the substrate (60), making it easy to control the discharge of the coating liquid through the first slot (115).

[0103] The third die block (130) may have a triangular upper cross-section. The third die block (130) also has a plate-like structure extending along the width direction. The third die block (130) has a third die lip (132) that forms its leading end with respect to the substrate (60).

[0104] A shim (127) may also be provided between the second die block (120) and the third die block (130). The shim (117) provided between the first die block (110) and the second die block (120) may be referred to as an upper shim (117), and the shim (127) provided between the second die block (120) and the third die block (130) may be referred to as a lower shim (127). The upper shim (117) and the lower shim (127) may be the same.

[0105] Here, the lower surface of the second die block (120) and the lower surface of the third die block (130) may not be in contact with the base (105), so that a bending space (S) may be formed between them and the upper surface of the base (105). Alternatively, if the lower surface of the second die block (120) and the lower surface of the third die block (130) have the configuration described with reference to FIG. 6, even if they are in contact with the base (105), a bending space (S) may be formed between them and the base (105). It has been described that the first die block (110) includes a manifold (118) that receives a coating liquid and communicates with the first slot (115). The third die block (130) may include a manifold (138) that receives a coating liquid that is the same as or different from the coating liquid and communicates with the second slot (125). For convenience, the manifold (118) formed in the first die block (110) may be referred to as an upper manifold (118), and the manifold (138) formed in the third die block (130) may be referred to as a lower manifold (138). The coating solution contained in the upper manifold (118) may be referred to as a first coating solution (150), and the coating solution contained in the lower manifold (138) may be referred to as a second coating solution (160). In this way, the manifolds (118, 138) are formed in the first die block (110) and the third die block (130), respectively. By doing so, the deformation of the second die block (120), which is structurally the most vulnerable, can be less affected. In addition, if the second die block (120) is divided into a left die (back) and a right die (front), and the left die is configured to move integrally with the first die block (110), and the right die is configured to move integrally with the third die block (130), a structure can be implemented in which the left die block and the right die block can slide at the interface between the left and right dies, and a structure can be implemented in which the positional change of the first slot (115) and the second slot (125) is made easier.

[0106] Referring to FIGS. 9 and 10, a first discharge port (116) communicating with a first slot (115) is formed between the first die lip (112) and the second die lip (122), and a second discharge port (126) communicating with a second slot (125) is formed between the second die lip (122) and the third die lip (132). The second discharge port (126) discharges a second coating liquid (160) contained in the lower manifold (138) shown in FIG. 8 onto the substrate (60), and the first discharge port (116) is positioned spaced apart from the second discharge port (126) in the downstream direction in the coating direction, and discharges a first coating liquid (150) contained in the upper manifold (118) shown in FIG. 8 onto the substrate (60). That is, a double layer coating can be achieved by forming an upper layer using the first discharge port (116) and forming a lower layer using the second discharge port (126).

[0107] In this way, the coating roll (50) that is provided to be rotatable is placed toward the discharge direction of the dual slot die coater (200), and by rotating the coating roll (50), the substrate (60) to be coated is driven, and the first coating liquid (150), which is a first electrode active material slurry, and the second coating liquid (160), which is a second electrode active material slurry, are continuously brought into contact with the surface of the substrate (60), thereby simultaneously coating a two-layer structure on the substrate (60). The second coating liquid (160) is first coated on the substrate (60) to form a lower slurry layer, and almost simultaneously, the first coating liquid is coated on the lower slurry layer to form an upper slurry layer.

[0108] In this embodiment as well, the center of rotation axis (50_C) of the coating roll (50) is moved toward the second die block (120) rather than the upper portion (112a) of the first die lip (112).

[0109] In FIGS. 8 and 9, the vertical line from the rotation axis center (50_C) of the coating roll (50) as the first reference line (L1) is shown to be aligned with the upper portion (112a) of the first die lip (112). In the present embodiment, the vertical line (Lc) from the rotation axis center (50_C) of the coating roll (50) can be aligned to the right, i.e., forward, of the first reference line (L1).

[0110] In FIGS. 8 and 9, the second reference line (L2) is shown as a vertical line aligned with the lower portion (132b) of the third die lip (132) at the center of the rotation axis (50_C) of the coating roll (50). In the present embodiment, the vertical line (Lc) at the center of the rotation axis (50_C) of the coating roll (50) can be aligned to the left, i.e., rearward, of the second reference line (L2).

[0111] For example, the rotation axis center (50_C) of the coating roll (50) may be aligned with the center (between reference numerals 112a and 112b) of the first die lip (112) and may be at the LA position. A vertical line (Lc) from the rotation axis center (50_C) of the coating roll (50) passes through the center of the first die lip (112).

[0112] For another example, the rotational axis center (50_C) of the coating roll (50) may be aligned with the upper portion (122a) of the second die lip (122) and may be at the LB position. A vertical line (Lc) from the rotational axis center (50_C) of the coating roll (50) passes through the upper portion (122a) of the second die lip (122).

[0113] For another example, the rotational axis center (50_C) of the coating roll (50) may be aligned with the lower portion (112b) of the first die lip (122). A vertical line (Lc) from the rotational axis center (50_C) of the coating roll (50) passes through the lower portion (112b) of the first die lip (112).

[0114] For another example, the center of rotation axis (50_C) of the coating roll (50) can be aligned at a point 1 mm away from the lower portion (112b) of the first die lip (122) toward the second die lip (122). The position of the second die lip (122) can change depending on the thickness of the upper core (117). When the thickness of the upper core (117) is 1 mm, the point 1 mm away from the lower portion (112b) of the first die lip (122) toward the second die lip (122) can be the upper portion (122a) of the second die lip (122), i.e., the LB position.

[0115] For another example, the center of rotation axis (50_C) of the coating roll (50) may be located in the middle of the second die lip (122) (between reference numerals 122a and 122b), in the lower part (122b) of the second die lip (122), or in the upper part (132a) of the third die lip (132).

[0116] At this time, since the bending effect changes according to the change in the rotation axis center (50_C) of the coating roll (50), it is desirable that the position of the bending center (142_C) also change. Therefore, it is desirable that the rotation axis center (50_C) and the bending center (142_C) of the coating roll (50) are aligned with each other.

[0117] For example, the position of the bending unit (140) is determined so that when the vertical line (Lc) from the rotation axis center (50_C) of the coating roll (50) passes through the center of the first die lip (112), the bending center (142_C) also passes through it. That is, when the rotation axis center (50_C) of the coating roll (50) is aligned with the center of the first die lip (112) and is at the LA position, the position of the bending unit (140) is changed so that the bending center (142_C) is also at the LA position.

[0118] Likewise, the position of the bending unit (140) is determined so that when the vertical line (Lc) from the rotation axis center (50_C) of the coating roll (50) passes through the upper portion (122a) of the second die lip (122), the bending center (142_C) also passes through it. That is, when the rotation axis center (50_C) of the coating roll (50) is aligned with the upper portion (122a) of the second die lip (122) and is at the LB position, the position of the bending unit (140) is changed so that the bending center (142_C) is also at the LB position.

[0119] To this end, in the present invention, as shown in FIG. 7, a hole (H) for connecting the bending unit (140) and the base (105) is formed as a long hole so that the bending center (142_C) can also move when the vertical die alignment position is changed.

[0120] Since the hole (H) connecting the bending unit (140) and the base (105) is a long hole, the position of the bending unit (140) connected here can be moved forward and backward (see the two-way arrow). The position of the bending unit (140) can be located at the center of the base (105), or can be placed closer to the second die block (120) or closer to the third die block (130) as needed. The closer the part is to the bending unit (140), the greater the force received and the greater the bending effect can be achieved. The bending unit (140) can push the base (105) toward the discharge direction or pull the base (105) in the opposite direction to the discharge direction.

[0121] Preferably, even in the dual slot die coater (200), the rotational axis center (50_C) of the coating roll (50) is aligned so as to move toward the second die block (120) rather than the upper portion (112a) of the first die lip (112). For example, the rotational axis center (50_C) of the coating roll (50) is not aligned with the upper portion (112a) of the first die lip (112), i.e., the upper portion of the first die block (110), but is changed to the lower portion of the first die block (110) or another location. In addition, the bending center (142_C) is also changed to a position aligned therewith. Through this, a stable coating bead can be formed.

[0122] Comparative example

[0123] Fig. 11 is a schematic cross-sectional view of a dual slot die coater according to a comparative example.

[0124] Referring to Fig. 11, the comparative example aligns the rotation axis center (50_C) and the bending center (142_C) of the coating roll (50) with the upper portion (112a) of the first die lip (112), which is a 'first die block upper' alignment method. This may cause the coating gap at the rear bead (BB) to become excessively large, which may cause the coating bead to not be formed stably and may cause a problem in which the coating bead becomes unstable and bursts out backward, resulting in a back leak.

[0125] Fig. 12 is a graph simulating the coating gap at each position when the center of rotation axis (50_C) of the coating roll is aligned with the upper part (112a) of the first die lip (112), as in a comparative example. It is assumed that the thickness of the core (117, 127) is 1 mm and the diameter of the coating roll (50) is 350 mm.

[0126] In Fig. 12, the vertical axis represents the physical thickness and gap of the die lips (indicated as upper LIP, middle LIP, and lower LIP), and the unit is mm. It is aligned with the upper part (112a) of the first die lip (112), so that the left side of the upper LIP is located at the vertical axis 0. In Fig. 12, the horizontal axis represents the gap between the die lip and the coating roll (indicated as C-Roll), and the unit is mm. The end of the die lip is at position 1 of the horizontal axis, and the outer circumference of the coating roll from the rotational axis center (50_C) of the coating roll is at position 2.5. Therefore, the gap set for calculation is a coating gap of 1.5 mm. An additional gap (Gap) is shown for each die lip position in Fig. 12. The additional gap is an increased value compared to the set coating gap of 1.5 mm.

[0127] The upper plate / top plate refers to the upper portion (112a) of the first die lip (112). Since the rotational axis center (50_C) of the coating roll is located at that position, the additional gap compared to the set coating gap is 0.0. The upper plate / bottom plate is an additional gap at the lower portion (112b) of the first die lip (112), and is calculated to be 2.9 ㎛. The middle plate / top plate is an additional gap at the upper portion (122a) of the second die lip (122), and is calculated to be 11.4 ㎛. The middle plate / center plate is an additional gap at the midpoint between the upper portion (122a) and the lower portion (122b) of the second die lip (122), and is calculated to be 17.9 ㎛. The middle plate / bottom plate is an additional gap at the lower portion (122b) of the second die lip (122), and is calculated to be 25.7 ㎛. The lower / upper part is an additional gap from the upper part (132a) of the third die lip (132), and was calculated to be 44.4 μm. The lower / lower part is an additional gap from the lower part (132b) of the third die lip (132), and was calculated to be 137.7 μm. In this way, the additional gap increases as the distance from the center of rotation axis (50_C) of the coating roll deviates.

[0128] The additional gap in the upper layer was calculated as 7.1 ㎛ by taking the average of the additional gap of 2.9 ㎛ in the upper / lower plate and the additional gap of 11.4 ㎛ in the middle / upper plate, and the additional gap in the lower layer was calculated as 35.0 ㎛ by taking the average of the additional gap of 25.7 ㎛ in the middle / lower plate and the additional gap of 44.4 ㎛ in the lower plate / upper plate. Since the rotational axis center (50_C) of the coating roll is aligned with the upper portion (112a) of the first die lip (112) and thus is biased toward the first die block (110), it can be seen that an additional coating gap of 27.9 ㎛ (relative lower layer additional GAP) is generated in the lower portion due to the curvature of the coating roll (50).

[0129] In this way, when the center of rotation axis (50_C) of the coating roll (50) is aligned with the upper portion (112a) of the first die lip (112), a problem occurs in which the coating gap varies greatly in the front-back direction of the slot die coater (100) due to the curvature of the coating roll (50), and in particular, it can be confirmed that the coating gap increases more severely in the lower portion than in the upper portion.

[0130] In particular, in the case of a dual slot die coater (200), the upper part of the first die block (110), which is the alignment position, and the rear bead (BB) position are farther apart than in the single layer slot die coater (100), so the coating gap at the rear bead (BB) position becomes larger, making the upper alignment double layer coating of the first die block (110) particularly vulnerable to back leak.

[0131] Example

[0132] In the present invention, the rotational axis center (50_C) of the coating roll (50) can be moved toward the second die block (120) rather than the upper portion (112a) of the first die lip (112), thereby preventing back leak.

[0133] Fig. 13 is a graph simulating the coating gap at each position when the rotational axis center (50_C) of the coating roll (50) is aligned with the lower portion (112b) of the first die lip (112) according to one embodiment of the present invention. As in the comparative example, it was assumed that the thickness of the core (117, 127) was 1 mm and the diameter of the coating roll (50) was 350 mm.

[0134] As shown in Fig. 13, the additional gap for each die lip position is compared with the comparative example as follows. Since the rotation axis center (50_C) of the coating roll is located at the upper / lower, the additional gap compared to the set coating gap is 0.0. The upper / upper part is away from the rotation axis center (50_C) of the coating roll, so the additional gap was calculated to be 2.9 ㎛. The additional gap at the middle / upper part was 2.9 ㎛, the additional gap at the middle / middle part was 6.4 ㎛, the additional gap at the middle / lower part was 11.4 ㎛, the additional gap at the lower / upper part was 24.7 ㎛, and the additional gap at the lower / lower part was 100.8 ㎛. Although the additional gap increases as the rotation axis center (50_C) of the coating roll is located away from the position, in the present embodiment, the additional gap at each die lip position is significantly smaller than in the comparative example. Therefore, the back bead is not moved as far away as in the comparative example, so the back leak is improved.

[0135] In addition, the additional gap in the upper layer was calculated to be 1.4 ㎛, and the additional gap in the lower layer was calculated to be 18.1 ㎛. Even though a coating gap occurs in the lower layer due to the curvature of the coating roll (50) when the rotation axis center (50_C) of the coating roll is not aligned with the upper portion (112a) of the first die lip (112) and comes slightly closer to the second die block (120), it can be seen that a coating gap of 16.6 ㎛, which is much smaller than that in the comparative example, occurs. Therefore, the coating conditions of the upper and lower layers become more similar, so that the coating layer quality control becomes more certain. By reducing the difference in the coating gap between the upper and lower layers, the individual loading quality of the upper and lower layers can be secured.

[0136] FIG. 14 is a graph simulating the coating gap by position when the center of rotation axis (50_C) of the coating roll is aligned with the upper part (122a) of the second die lip (122) according to another embodiment of the present invention.

[0137] Referring to Fig. 14, the additional gap for each die lip position is compared with the comparative example as follows. Since the center of rotation axis (50_C) of the coating roll is located at the middle / upper, the additional gap is 0.0 compared to the set coating gap. The upper / upper and upper / lower plates are away from the center of rotation axis (50_C) of the coating roll, so the additional gaps were calculated to be 11.4 ㎛ and 2.9 ㎛, respectively. The additional gap at the middle / center was 0.7 ㎛, the additional gap at the middle / lower plate was 2.9 ㎛, the additional gap at the lower plate / upper plate was 10.8 ㎛, and the additional gap at the lower plate / lower plate was 69.7 ㎛. Although the additional gap increases as the center of rotation axis (50_C) of the coating roll is located away from the position, in the present embodiment as well, the additional gap at each die lip position is significantly smaller than in the comparative example. Therefore, the back bead is not as far away as in the comparative example, so the back leak is greatly improved.

[0138] Also, according to FIG. 14, the additional gap in the upper layer was calculated to be 1.4 μm, and the additional gap in the lower layer was calculated to be 6.8 μm. Even if a coating gap occurs in the lower layer due to the curvature of the coating roll (50) as the rotational axis center (50_C) of the coating roll is not aligned with the upper portion (112a) of the first die lip (112) and gets closer and closer to the second die block (120), it can be seen that a coating gap of 5.4 μm, which is much smaller than that of the comparative example or the embodiment of the present invention, occurs, and this degree is practically no difference in the coating gap. Therefore, by making the coating gaps of the upper and lower layers uniform, the individual loading quality of the upper and lower layers can be secured.

[0139] As mentioned above, since the bending effect changes according to the change in the rotation axis center (50_C) of the coating roll (50), it is desirable to also change the position of the bending center (142_C). If the hole (H) for connecting the bending unit (140) and the base (105) is formed in a circular shape, the position of the bending unit (140) is fixed. However, if the hole (H) for connecting the bending unit (140) and the base (105) is formed as a long hole as proposed in the present invention, the bending unit (140) can change its position along the front-back direction so as to match the rotation axis center (50_C) of the coating roll (50).

[0140] Fig. 15 shows the results of a center and side loading test according to bending levels (-40 μm to 40 μm) while only changing the alignment of the rotational axis center (50_C) of the coating roll (50) from the lower portion (112b) of the first die lip (112) to the upper portion (132a) of the third die lip (132) without moving the bending center (142_C). The bending center (142_C) was fixed in alignment with the lower portion (112b) of the first die lip (112) and was not moved.

[0141] In Fig. 15, the horizontal axis represents the rotation axis center (50_C) of the coating roll (50), and the unit is an arbitrary unit. When the rotation axis center (50_C) of the coating roll (50) is aligned with the lower portion (112b) of the first die lip (112), the value of the horizontal axis is 0. As the rotation axis center (50_C) of the coating roll (50) moves toward the upper portion (132a) of the third die lip (132), the horizontal axis has a negative value.

[0142] In Fig. 15, the vertical axis represents the loading difference between the center and side portions of the coating layer, and the unit is arbitrary. The greater the center portion loading, the more positive the value.

[0143] A bending level of -40㎛ is a condition when the base (105) is pushed that much to press the bending space (S), a bending level of 0 is a condition when no bending occurs, and a bending level of 40㎛ is a condition when the base (105) is pulled that much to increase the bending space (S).

[0144] When the rotational axis center (50_C) of the coating roll (50) is aligned with the lower portion (112b) of the first die lip (112), if the bending level is 40 μm, the loading difference between the center portion and the side portion is approximately 10, and as the rotational axis center (50_C) of the coating roll (50) moves toward the upper portion (132a) of the third die lip (132), the loading difference between the center portion and the side portion gradually decreases. When the rotational axis center (50_C) of the coating roll (50) is aligned with the lower portion (112b) of the first die lip (112), if the bending level is 0 μm, the loading difference between the center portion and the side portion is almost zero, and as the rotational axis center (50_C) of the coating roll (50) moves toward the upper portion (132a) of the third die lip (132), the loading difference between the center portion and the side portion gradually becomes a negative value. When the center of rotation axis (50_C) of the coating roll (50) is aligned with the lower part (112b) of the first die lip (112), and the bending level is -40㎛, the loading difference between the center part and the side part is about -10, and as the center of rotation axis (50_C) of the coating roll (50) moves toward the upper part (132a) of the third die lip (132), the loading difference between the center part and the side part becomes an increasingly negative value.

[0145] However, the loading difference (△BL1) by bending level when the rotation axis center (50_C) of the coating roll (50) is aligned with the lower part (112b) of the first die lip (112) is different from the loading difference (△BL2) by bending level when the rotation axis center (50_C) of the coating roll (50) is aligned with the upper part (132a) of the third die lip (132).

[0146] As shown in FIG. 15, it is analyzed that the bending effect is somewhat different depending on the position of the rotation axis center (50_C) of the coating roll (50). The interaction must be taken into account. Since the bending effect is different depending on the position of the rotation axis center (50_C) of the coating roll (50), it is desirable to also change the position of the bending center (142_C). The side of the pressurized portion where the bending force is applied by the bending unit (140) can be made to have the smallest coating gap, thereby maintaining the bending effect (sensitivity).

[0147] According to the present invention, by forming a hole (H) for connecting the bending unit (140) and the base (105) as a long hole, the bending center (142_C) can also move when the vertical die alignment position is changed. The long hole (H) can be extended from behind the upper portion (112a) of the first die lip (112) to in front of the lower portion (132b) of the third die lip (132).

[0148] In this way, in the present invention, when the rotation axis center (50_C) of the coating roll (50) is changed with respect to the slot die coater (100, 200), the bending center (142_C) by the bending unit (140) can also move together.

[0149] Accordingly, the rotational axis center (50_C) and the bending center (142_C) of the coating roll (50) may be aligned with each other and moved toward the second die block (120) more than the upper portion (112a) of the first die lip (112). The position of the bending pressurization portion pressed by the bending unit (140) becomes the place where the coating gap is the smallest. According to the present invention, the rotational axis center (50_C) and the bending center (142_C) of the coating roll (50) may be aligned with any part of the die lip of the vertical die type slot die coater (100, 200).

[0150] In particular, since the coating liquid injection direction of the dual slot die coater (200) is the center of the die blocks (110, 130), the amount of liquid applied to the center is greater than that to the side, and thus, an uneven coating profile may be obtained in the width direction (perpendicular to the MD direction) of the substrate (60). In other words, the loading of the coating liquid may be concentrated on the width direction centers of the first slot (115) and the second slot (125). In such a case, the position of the second die lip (122) and the third die lip (132) may be changed by pushing or pulling the portion of the base (105) corresponding to the second die block (120) or the third die block (130) with the bending unit (140), thereby adjusting the coating gap and controlling the loading distribution accordingly. By pushing each of the die blocks (110, 120, 130) toward the discharge direction with the bending unit (140), the coating gap of the center portion may be reduced. Conversely, by pulling each die block (110, 120, 130) in the opposite direction of the discharge direction with the bending unit (140), the coating gap in the center portion can be increased.

[0151] As described above, in the comparative example where the center alignment is different from that of the present invention, the coating gap at the rear bead widens, resulting in an unstable coating bead, which causes back leaks. According to the present invention, a stable coating bead can be formed by changing the alignment positions of the coating roll (50) and the bending unit (140). Furthermore, the bending center (142_C) can also be moved to achieve a uniform coating profile.

[0152] Meanwhile, the first die lip (112), the second die lip (122), and the third die lip (132) may be positioned on the same straight line. In addition, the thickness of the third die lip (132) may be greater than the thickness of the first die lip (112) and the thickness of the second die lip (122).

[0153] The optimum coating area (window margin) exists between the area where leakage occurs and the area where side rings occur. The wider this optimum process area is, the better the productivity is. The coating gap has a great influence on the size and shape of the coating bead formed between the substrate (60) and the die lips (112, 122, 132) during coating, and the position of the dynamic contact line. According to the present invention, there is an advantage in that the coating gap can be maintained constant by aligning the die lips (112, 122, 132), and by adjusting the size of the die lips (112, 122, 132), the optimum process area can be expanded, and the initial conditions such as the properties of the coating liquid, the flow rate and speed of the coating liquid can be adjusted, allowing more leeway in setting the initial conditions to minimize leakage.

[0154] Preferably, referring again to FIG. 9, the thickness (D3) of the third die lip (132) is made larger than the thickness (D2) of the second die lip (122) and the thickness (D1) of the first die lip (112). Thus, the thickness (D3) of the third die lip (132) is larger than the average thickness of the thickness (D1) of the first die lip (112) and the thickness (D2) of the second die lip (122). In this way, the thickness (D3) of the third die lip (132) is the largest (D3>D2, D3>D1, D3>(D1+D2) / 2). In addition, the thickness (D2) of the second die lip (122) and the thickness (D1) of the first die lip (112) can be made equal to each other. The thickness (D1) of the first die lip (112) can also be made larger than the thickness (D2) of the second die lip (122).

[0155] The thickness (D3) of the third die lip (132): the thickness (D1) of the first die lip (112) can be 1.2:1 or more. That is, the thickness (D3) of the third die lip (132) can be 1.2 times or more the thickness (D1) of the first die lip (112). If the thickness (D3) of the third die lip (132) is greater than the thickness (D1) of the first die lip (112), an appropriate process area can be increased. However, if the thickness (D3) of the third die lip (132) is 1.2 times or more the thickness (D1) of the first die lip (112), there is an effect of clearly suppressing the occurrence of leaking. If the thickness (D1) of the first die lip (112) is greater than the thickness (D3) of the third die lip (132), leaking occurs.

[0156] The thickness (D3) of the third die lip (132): the thickness (D2) of the second die lip (122) can be from 1.2:1 or more. That is, the thickness (D3) of the third die lip (132) can be 1.2 times or more the thickness (D2) of the second die lip (122). If the thickness (D3) of the third die lip (132) is greater than the thickness (D2) of the second die lip (122), an appropriate process area can be increased, but if the thickness (D3) of the third die lip (132) is 1.2 times or more the thickness (D2) of the second die lip (122), there is an effect of clearly suppressing the occurrence of leaking. If the thickness (D3) of the third die lip (132) and the thickness (D2) of the second die lip (122) are the same, leaking occurs. If the thickness (D2) of the second die lip (122) is greater than the thickness (D3) of the third die lip (132), other pattern defects may occur even if leaking does not occur.

[0157] According to the above example, the thickness (D3) of the third die lip (132) is the largest because it is larger than the thickness (D2) of the second die lip (122) and the thickness (D1) of the first die lip (112). As the thickness (D3) of the third die lip (132) increases, the appropriate process area widens. Therefore, more leeway can be provided in controlling the coating gap or setting initial conditions. Accordingly, according to this configuration, productivity is excellent, and the dynamic contact line during coating can be used in various positions depending on the target coating product and quality. According to the present invention, as a result of the expanded appropriate process area, the leaking limit can be improved, i.e., increased. And the side ring occurrence area can be reduced. As the coating gap decreases, when the dynamic contact line moves in the opposite direction of the coating, leaking occurs above a certain level. According to this configuration, the leaking can be improved by increasing the thickness (D3) of the third die lip (132). This is because the second coating liquid (160) can be retained in large quantities in the third die lip (132) without falling back. According to the present invention, leakage is reduced even when the coating gap is insufficient or the amount of coating liquid supplied is large compared to the traveling speed of the substrate (60).

[0158] As a preferred example, the thickness (D3) of the third die lip (132): the thickness (D2) of the second die lip (122): the thickness (D1) of the first die lip (112) is 1.5:0.5:1.

[0159] For another example, the thickness (D3) of the third die lip (132) and the thickness (D1) of the first die lip (112) may be equal to each other and greater than the thickness (D2) of the second die lip (122) (D3=D1>D2).

[0160] The thickness (D3) of the third die lip (132): the thickness (D2) of the second die lip (122) can be from 1.2:1 or more. That is, the thickness (D3) of the third die lip (132) can be 1.2 times or more the thickness (D2) of the second die lip (122). If the thickness (D3) of the third die lip (132) is greater than the thickness (D2) of the second die lip (122), an appropriate process area can be increased, but if the thickness (D3) of the third die lip (132) is 1.2 times or more the thickness (D2) of the second die lip (122), there is an effect of clearly suppressing the occurrence of leaking. If the thickness (D3) of the third die lip (132) and the thickness (D2) of the second die lip (122) are the same, leaking occurs. If the thickness (D2) of the second die lip (122) is greater than the thickness (D3) of the third die lip (132), other pattern defects may occur even if leaking does not occur.

[0161] The thickness (D1) of the first die lip (112) can be made the same as the thickness (D3) of the third die lip (132) and can be made greater than the thickness (D2) of the second die lip (112). The thickness (D1) of the first die lip (112) is not made greater than the thickness (D3) of the third die lip (132) to prevent leakage.

[0162] According to the above example, the thickness (D3) of the third die (132) is large, thereby widening the appropriate process area. Therefore, more leeway can be provided in controlling the coating gap or setting initial conditions.

[0163] For example, the method for coating electrode active material slurry using a slot die coater of the present invention is applied to the manufacture of a positive electrode of a secondary battery. The positive electrode has a structure in which a lower active material layer formed by a lower slurry layer and an upper active material layer formed by an upper slurry layer are sequentially laminated on a current collector. The lower active material layer contains a high content of a conductive material, and the upper active material layer contains a relatively low content of a conductive material. In this case, the conductive material content of the lower active material layer can be controlled within the range of 0.5 to 5 wt%. By reducing the conductive material content of the upper active material layer, the active material content on the electrode surface can be increased and the electrical conductivity can be lowered to a certain level. In particular, when the conductive material content of the upper active material layer is controlled to a very low level of 0.02 wt% or less, the exothermic reaction during a short circuit inside the cell can be reduced.

[0164] In another example, the average particle size (P1) of the active material forming the lower active material layer is in the range of 50 to 95% of the average particle size (P2) of the active material forming the upper active material layer. In this case, an active material having a relatively small particle size is applied to the lower active material layer. By applying an active material having a relatively large particle size to the upper active material layer, electrolyte impregnation can be facilitated and smooth ion and hole movement can be induced.

[0165] Here, the flow rate ratio of the first coating liquid and the second coating liquid (160) may be 1:1. The viscosity of the first coating liquid and the second coating liquid (160) may be 1000 cps or more. Since it is necessary to be able to coat a coating liquid having a viscosity of 1000 cps or more, the dual slot die coater (200) of the present invention has a different structure from a device that applies a common resin liquid such as a photosensitive emulsion liquid, a magnetic liquid, a liquid that provides anti-reflection or anti-glare properties, a liquid that provides a viewing angle expansion effect, a pigment liquid for a color filter, and the like, and is not a device that can be achieved by changing it. The first coating liquid and the second coating liquid (160) may include graphite, a conductive material, CMC, and a binder.

[0166] Under the above coating conditions, most preferably, the thickness (D3) of the third die lip (132): the thickness (D2) of the second die lip (122): the thickness (D1) of the first die lip (112) is 3:1:1. According to this dual slot die coater (200), the process efficiency can be increased and the defect rate can be reduced when forming a two-layer structure of an active material layer on a current collector.

[0167] For example, the present invention can be applied to the manufacture of a positive electrode of a secondary battery by coating a positive electrode active material slurry using the dual slot die coater (200). The positive electrode includes a current collector and a positive electrode active material layer formed on the surface of the current collector. The current collector may be an electrically conductive material such as Al or Cu, and may be used appropriately according to the polarity of the current collector electrode known in the secondary battery field. The positive electrode active material layer may further include one or more of a plurality of positive electrode active material particles, a conductive material, and a binder. In addition, the positive electrode may further include various additives for the purpose of supplementing or improving electrochemical characteristics.

[0168] The active material is not limited to a specific component as long as it can be used as a positive electrode active material of a lithium ion secondary battery. Non-limiting examples thereof include layered compounds such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M xNi-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn 2-x M x A lithium manganese composite oxide represented by O2 (wherein M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a part of the Li in the chemical formula is replaced with an alkaline earth metal ion; a disulfide compound; and Fe2(MoO4)3 may include one or a mixture of two or more thereof. In the present invention, the positive electrode may include at least one of a polymer-based solid electrolyte, an oxide-based solid electrolyte and a sulfide-based solid electrolyte as a solid electrolyte material.

[0169] The conductive material can be added typically in an amount of 1 wt% to 20 wt% based on the total weight of the mixture including the active material. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, it may include one or a mixture of two or more selected from the following conductive materials: graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fiber or metal fiber; metal powders such as fluorinated carbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0170] The above binder is not particularly limited as long as it is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and examples thereof include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluororubber, and various copolymers. The binder may typically be included in an amount of 1 wt% to 30 wt%, or 1 wt% to 10 wt%, relative to 100 wt% of the electrode layer.

[0171] The present invention can also be applied to the manufacture of a negative electrode of a secondary battery by coating a negative electrode active material slurry using a dual slot die coater (200). The negative electrode includes a current collector and a negative electrode active material layer formed on the surface of the current collector. The negative electrode active material layer may further include one or more of a plurality of negative electrode active material particles, a conductive agent, and a binder. In addition, the negative electrode may further include various additives for the purpose of supplementing or improving electrochemical characteristics.

[0172] The above negative active material is a carbon material such as graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotube, carbon nanohorn, lithium metal material, alloy material such as silicon or tin, Nb2O5, Li5Ti4O 12 , oxide materials such as TiO2, or their composites can be used. For the negative electrode, the conductive material, binder, and current collector, refer to the content described for the positive electrode.

[0173] The electrode active material slurry containing the positive or negative active material has a very high viscosity. For example, the viscosity may be 1000 cps or more. The viscosity of the electrode active material slurry for forming a secondary battery electrode may be 2000 cps to 30000 cps. For example, the negative electrode active material slurry may have a viscosity of 2000 cps to 4000 cps. The positive electrode active material slurry may have a viscosity of 8000 cps to 30000 cps. Since it is necessary to be able to coat a coating liquid having a viscosity of 1200 cps or more, the dual slot die coater (200) of the present invention has a different structure from that of a device that applies a normal resin liquid such as a photosensitive emulsion liquid, a magnetic liquid, a liquid that provides anti-reflection or anti-glare properties, a liquid that provides a viewing angle enlargement effect, a pigment liquid for a color filter, etc., and it is not a device that can be achieved by changing it. The dual slot die coater (200) of the present invention is for applying an electrode active material slurry that may include an active material having a particle size of, for example, an average particle diameter of about 10 ㎛, and therefore is different from the structure of a device for applying another coating liquid that does not include particles of such a size, and is not a device that can be achieved by changing it.

[0174] Fig. 16 is a modified example of Fig. 8.

[0175] Referring to Fig. 16, the third die lip (132) is retracted further than the first die lip (112) or the second die lip (122).

[0176] The distance (H1) between the substrate (60) and the first die lip (112) and the distance (H2) between the substrate (60) and the second die lip (122) are greater than the distance (H3) between the substrate (60) and the third die lip (132). By positioning the third die lip (132) further away from the substrate (60) in the opposite direction of the discharge direction than the first die lip (112) and the second die lip (122), this distance difference can be generated to form a step between the die lips. The distance (H1) between the substrate (60) and the first die lip (112) and the distance (H2) between the substrate (60) and the second die lip (122) can be equal to each other.

[0177] Accordingly, a predetermined step (D') is formed between the second discharge port (126) and the first discharge port (116). This step (D') is the distance (H3) between the substrate (60) and the third die lip (132) minus the distance (H1) between the substrate (60) and the first die lip (112). Since the second discharge port (126) and the first discharge port (116) are arranged at positions spaced apart from each other horizontally by this step (D'), there is no concern that the first coating liquid (150) discharged from the first discharge port (116) will flow into the second discharge port (126), or that the second coating liquid (160) discharged from the second discharge port (126) will flow into the first discharge port (116). As described above, the configuration of this embodiment is characterized in that the second die block (120) and the third die block (130) forming the second discharge port (126) are spaced apart from each other.

[0178] As shown, with the die-lips (112, 122, 132) positions set, the first discharge port (116) is positioned spaced apart from the second discharge port (126) in the downstream direction of the coating direction. By simultaneously discharging the coating liquid through the second discharge port (126) and the first discharge port (116) while moving the substrate (60) from the third die-lip (132) toward the first die-lip (112), a two-layer active material layer can be formed on the substrate (60).

[0179] The present invention is to move only the lower layer upstream further away from the substrate (60) based on the lower layer slurry, i.e., the second coating liquid (160) discharged from the second discharge port (126). In other words, by creating a height difference between the second die block (120) and the third die block (130), which are two plates forming the second discharge port (126), the third die block (130) is moved further away from the substrate (60). This is different from the case where only the movement of the discharge port itself is utilized without distinguishing between the upstream and downstream.

[0180] The ratio of the average thickness (T1) of the lower slurry layer formed by the second coating liquid (160) discharged through the second discharge port (126) and the average thickness (T2) of the upper slurry layer formed by the first coating liquid discharged through the first discharge port (116) may be in the range of 1:3 to 3:1 (T1:T2). The thickness ratio relatively indicates the average value of the length in the thickness direction of each layer. In addition, the average thicknesses (T1, T2) of the lower slurry layer and the upper slurry layer may be 40 to 200 ㎛, respectively.

[0181] The thickness of the slurry layer as described above can be seen as the pressure of the supplied coating liquid. When the pressure of the first coating liquid (150) is supplied more than three times that of the second coating liquid (160) so that the thickness ratio of the lower slurry layer and the upper slurry layer is 1:3 or more, the upper layer has a stronger pressure than the lower layer, so the second coating liquid (160) is pushed backward in the opposite direction to the coating progress direction, which increases the possibility of leakage, and the second coating liquid (160) may not be supplied properly due to the strong pressure of the first coating liquid (150). In addition, because the high pressure of the first coating liquid (150) causes the supply of the second coating liquid (160) to be uneven, there is a problem that it is difficult for the lower slurry layer to be formed uniformly.

[0182] Meanwhile, when the pressure of the second coating solution (160) is supplied more than three times the pressure of the first coating solution (150) so that the thickness ratio of the lower slurry layer and the upper slurry layer is 3:1 or more, there is a problem that the supply of the first coating solution (150) becomes difficult or the coating of the first coating solution (150) is pushed in the coating progress direction, making the coating solution surface uneven.

[0183] The above step (D') is preferably in the range of 20 to 70% of the average thickness (T1) of the lower slurry layer and the average thickness (T2) of the upper slurry layer. If the range is less than 20%, the effect of shortening the loading drop-out length when the supply of the coating liquid is stopped is small. If the range exceeds 70%, the total area of ​​the space where the coating liquid stays for coating, that is, the space between the die lips (122, 132) and the lower slurry layer, is insufficient compared to the amount of the coating liquid, so that the supplied second coating liquid (160) is not coated and leaks backward, resulting in leakage.

[0184] For intermittent coating, when the supply of the coating solution is stopped during pattern formation, the loading is gently cut off, resulting in a loading-off phenomenon. This loading-off phenomenon occurs when, when the supply of the coating solution is stopped for end formation, the residual coating solution that forms a meniscus or bead between the dual slot die coater (200) and the substrate (60) is coated on the substrate (60). In the present embodiment, since the third die block (130) is retracted as shown in FIG. 16, the amount of the residual coating solution that forms a meniscus or bead between the dual slot die coater (200) and the substrate (60) is reduced. The length (S') from the upper die lip (112) to the meniscus of the second coating solution (160) is shortened. Accordingly, when the coating solution is stopped, the loading is not gently cut off, and the length of the loading is cut off is short. Accordingly, the pattern end can be ideally formed almost perpendicular to the substrate (60), and the length of the loading-off section can be reduced. The loading-off section acts as a wasteful portion that is discarded, which results in a decrease in process efficiency and an increase in manufacturing costs. According to this configuration, since the loading-off section is shortened, the wasteful portion is reduced, resulting in an increase in process efficiency and a decrease in manufacturing costs.

[0185] For another example, the first die lip (112) may be retracted relative to the second die lip (122) or the third die lip (132).

[0186] In this case, although not separately illustrated, the distance (H1) between the substrate (60) and the first die lip (112), the distance (H2) between the substrate (60) and the second die lip (122), and the distance (H3) between the substrate (60) and the third die lip (132) shown in FIG. 16 are in the relationship H1>H2, H1>H3. At this time, H2 may be equal to H3. By positioning the first die lip (112) further from the substrate (60) in the opposite direction of the discharge direction than the second die lip (122) and the third die lip (132), this distance difference can be generated to form a step between the die lips. In this case, the upper coating gap and the lower coating gap can be individually controlled depending on the degree of retreat of the first die lip (112).

[0187] As another example, the second die lip (122) may be retracted further than the first die lip (112) or the third die lip (132).

[0188] In this case, although not separately illustrated, the distance (H1) between the substrate (60) and the first die lip (112), the distance (H2) between the substrate (60) and the second die lip (122), and the distance (H3) between the substrate (60) and the third die lip (132) shown in FIG. 16 are in the relationship H2>H1, H2>H3. At this time, H1 may be equal to H3. By positioning the second die lip (122) further away from the substrate (60) in the opposite direction of the discharge direction than the first die lip (112) and the third die lip (132), this distance difference can be generated to form a step between the die lips. In this case, when the supply of the coating liquid is stopped for intermittent coating, there is an effect of preventing the residual coating liquid attached to the second die lip (122) from falling messily on the substrate (60) and causing pattern defects such as drag lines.

[0189] As another example, the third die lip (132) may be further forward than the first die lip (112) or the second die lip (122).

[0190] In this case, although not shown separately, the distance (H1) between the substrate (60) and the first die lip (112), the distance (H2) between the substrate (60) and the second die lip (122), and the distance (H3) between the substrate (60) and the third die lip (132) shown in Fig. 16 are in the relationship H1>H3, H2>H3. At this time, H1 may be equal to H2. By pushing the position of the third die lip (132) closer to the substrate (60) than the first die lip (112) and the second die lip (122) toward the discharge direction, this distance difference can be generated, thereby forming a step between the die lips. In the case where too much additional gap is created in the lower layer and back leak occurs, in addition to reducing back leak by positioning the center of rotation axis (50_C) of the coating roll (50) toward the second die block (120) rather than the upper portion (112a) of the first die lip (112) as suggested in the present invention, by reducing the lower layer coating gap by advancing only the third die lip (132), back leak can be further reduced. Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations are possible by a person skilled in the art to which the present invention pertains within the technical spirit of the present invention and the scope of equivalents of the claims to be described below.

[0191] [Explanation of symbols]

[0192] 50: Coating roll 60: Base

[0193] 100: Slot die coater 105: Donation

[0194] 110: 1st die block 112: 1st die lip

[0195] 115: Slot, first slot 116: Outlet

[0196] 117: Heart 118: Manifold

[0197] 120: Second die block 122: Second die lip

[0198] 125: Second slot 126: Second outlet

[0199] 127: Heart 130: Third die block

[0200] 132: Third die lip 138: Manifold

[0201] 140: Bending unit 142: Die connection part

[0202] 144: Body 150: First coating solution

[0203] 160: Second coating solution 200: Dual slot die coater

[0204] B: Bolt H: Hole

[0205] S: Bending space

Claims

1. A slot die coater having a slot for ejecting a coating liquid in a direction opposite to gravity onto a substrate surface that is continuously transported by a coating roll. first die block; and A second die block is included, which forms the slot between the first die block and the second die block. A slot die coater, characterized in that the center of the rotation axis of the coating roll is positioned toward the second die block rather than the upper portion of the first die lip forming the leading end of the first die block with respect to the substrate.

2. A slot die coater, characterized in that in the first paragraph, the first die block is installed vertically as one piece with the base at the rear portion of the upper surface of the base, and the second die block is arranged at the front of the first die block.

3. A slot die coater according to claim 2, characterized in that the second die block does not interface with the base or, even if it interfaces, forms a bending space between the second die block and the base.

4. A slot die coater according to claim 3, characterized in that a bending unit is connected to the lower end of the base to deform the bending space.

5. A slot die coater characterized in that, in the fourth paragraph, a hole is formed in the base to connect the bending unit and the base, and the position of the bending unit can be changed by forming the hole in the front-back direction.

6. A slot die coater according to claim 4, characterized in that the center of the rotation axis of the coating roll is aligned with the center of bending by the bending unit.

7. A slot die coater according to claim 2, further comprising a third die block arranged on a front side of the second die block to form an additional slot between the third die block and the second die block.

8. A slot die coater according to claim 7, characterized in that the center of rotation axis of the coating roll is located in the middle of the first die lip, located at the lower portion of the first die lip, located at the upper portion of the second die lip forming the tip end of the second die block, located in the middle of the second die lip, located at the lower portion of the second die lip, or located at the upper portion of the third die lip forming the tip end of the third die block.

9. In the 7th paragraph, the second die block does not contact the base, or even if it does contact, forms a bending space between the base and the base, and a bending unit is connected to the lower end of the base to deform the bending space, and a hole formed in the base to connect the bending unit and the base is formed as a longitudinal hole in the front-back direction so that the center of the rotation axis of the coating roll is aligned with the center of the bending by the bending unit. A slot die coater.

10. A slot die coater, characterized in that in the 9th paragraph, the hole is extended from behind the upper portion of the first die lip to in front of the lower portion of the third die lip forming the leading end of the third die block.

11. A slot die coater having a slot for ejecting a coating liquid in a direction opposite to gravity onto a substrate surface that is continuously transported by a coating roll. A first die block installed vertically integrally with the base at the rear side of the upper surface of the base; a second die block forming the slot between the first die block; and Including a bending unit connected to the bottom of the above donation, A slot die coater characterized in that when the center of rotation axis of the coating roll is changed with respect to the slot die coater, the bending center by the bending unit also moves together.

12. A slot die coater according to claim 11, characterized in that the center of the rotation axis of the coating roll is positioned toward the second die block rather than the upper portion of the first die lip forming the leading end of the first die block with respect to the substrate.

13. A slot die coater characterized in that, in the 12th paragraph, a hole is formed in the base to connect the bending unit and the base, and the position of the bending unit can be changed by forming a hole in the front-back direction.

14. A slot die coater according to claim 11, further comprising a third die block arranged on a front side of the second die block to form an additional slot therebetween.

15. A slot die coater according to claim 14, characterized in that the cross section of the second die block is a right triangle.

16. In the 14th paragraph, the first die block, the second die block and the third die block have a first die lip, a second die lip and a third die lip forming a leading end of each die, the center of the rotation axis of the coating roll is positioned toward the second die block with respect to the substrate rather than the upper portion of the first die lip, and the first die lip, the second die lip and the third die lip are positioned on the same straight line, or the third die lip is retracted relative to the first die lip or the second die lip. A slot die coater.

17. In the 14th paragraph, the slot die coater, characterized in that the first die block, the second die block and the third die block have a first die lip, a second die lip and a third die lip forming the leading end of each die, the center of the rotational axis of the coating roll is positioned toward the second die block than the upper part of the first die lip with respect to the substrate, and the first die lip is retracted relative to the second die lip or the third die lip, or the second die lip is retracted relative to the first die lip or the third die lip, or the third die lip is advanced relative to the first die lip or the second die lip.

18. A slot die coater according to claim 16, characterized in that the thickness of the third die lip is greater than the thickness of the first die lip and the thickness of the second die lip.

19. A slot die coater, characterized in that in clause 16, the thickness of the third die lip is the same as the thickness of the first die lip and is greater than the thickness of the second die lip.

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