Modular coating bar for pattern coating and coating device including same

Abstract

A coating bar according to the present invention combines units, and thus can be easily extended or shortened in length. Accordingly, the coating bar can be applied to the manufacture of separators of various dimensions. In addition, the coating bar according to the present invention includes a third part which is a cylindrical tubular body that can be changed in position, and thus a coating pattern can be changed without replacing the coating bar in a coating device and merely by adjusting the position of the third part in the coating bar. Therefore, process efficiency is high.

Description

Modular coating bar for pattern coating and coating device including the same

[0001] This application claims priority to Korean Patent Application No. 10-2024-0093836, filed July 16, 2024. The present invention relates to a modular Meyer bar for pattern coating and a coating device including the same. It also relates to a method for manufacturing a separator using the device.

[0002]

[0003] Typically, a separator is interposed between the cathode and anode of a lithium secondary battery capable of repeated charging and discharging to prevent short circuits between the cathode and anode. The separator can be manufactured by using only a porous polymer substrate, or by applying and drying a slurry-like coating solution containing inorganic particles and a binder polymer to at least one surface of the porous polymer substrate, thereby forming an inorganic coating layer.

[0004] Meanwhile, various methods such as dip coating, gravure coating, and die coating are used to apply the coating solution to the substrate. Meanwhile, depending on the intended use or the specifications of the battery, the inorganic coating layer can be coated to have a predetermined pattern. However, since the shape of the coating Meyer bar of the coater is fixed, changing the coating device is inevitable when the shape or width of the pattern is changed. In addition, when a full-surface coating method using a conventional Meyer bar with a fixed diameter is applied, a portion is lost during slitting (cutting) into a final product with a predetermined specification, so manufacturing efficiency is low.

[0005]

[0006] The present invention was invented to solve the above-described problems, and the purpose of the invention is to provide a variable coating bar capable of adjusting the coating width and a coating device including the coating bar. In addition, the purpose of the invention is to provide a coating method for coating a porous coating layer in various patterns without replacing the coating bar using the coating device.

[0007]

[0008] The present invention relates to a coating-bar, and in one embodiment of the present invention, the coating-bar comprises one or more units, the units comprising a first cylindrical part, a second part, and a third part, the first part and the second part having different diameters, the first and second parts being connected to each other so as to have coaxially rotatable ends, and the third part having a hollow interior and a longitudinally penetrable structure, covering the outer side of at least one of the first and second parts, and being mounted so as to be slidably movable on the outer side of the first part and the second part.

[0009] In the aforementioned aspect, the unit may include one or more of each of the first, second and third parts.

[0010] In any of the aforementioned aspects, the first part may have a larger diameter than the second part.

[0011] In any of the aforementioned aspects, the difference in diameter between the first part and the second part may be 10 mm or more.

[0012] In any of the aforementioned aspects, the inner diameter of the third part may be equal to or greater than the outer diameter of the first part.

[0013] In any of the aforementioned aspects, the overall length of the third part in the unit may be equal to or greater than the overall length of the second part.

[0014] In any of the aforementioned aspects, the unit may have first parts disposed at each of the two ends, and one or more second parts may be connected so as to be rotatable coaxially between the two first parts.

[0015] In any of the aforementioned aspects, two second parts are connected between two first parts, and two third parts are included covering each of the first parts, each third part being equal to or longer than the length of each adjacent second part.

[0016] In any of the aforementioned aspects, at least one of the two first parts and the second part may include a fixing member capable of supporting the third part.

[0017] In any of the aforementioned aspects, the two fixing members may be configured to be inserted into the body of each part so as to be flush with the body surface and then protrude outward to support the inner surface of the third part.

[0018] The present invention also provides a coating device comprising a coating-bar according to any one of the aforementioned aspects.

[0019] In any of the aforementioned aspects, the coating device further includes a coater head and a receiving chamber located inside the coater head and containing a coating liquid, and the coating bar can be installed to be rotatable.

[0020] In any of the aforementioned aspects, the coating device may further include an ultrasonic generator positioned inside the coater head and / or inside the receiving chamber, and applying ultrasonic waves to the coating liquid received in the receiving chamber.

[0021]

[0022] The present invention may be implemented independently of each of the aforementioned embodiments. Furthermore, the present invention may be implemented by combining two or more of the aforementioned embodiments.

[0023] The coating bar according to the present invention is a combination of units, allowing for easy extension or shortening of the length of the coating bar. Therefore, it can be applied to the manufacture of membranes of various dimensions.

[0024] In addition, the coating bar according to the present invention includes a third part, which is a cylindrical tube whose position can be changed, so that the coating pattern can be changed by only adjusting the position of the third part in the coating bar without replacing the coating bar in the coating device, thereby increasing process efficiency.

[0025]

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the contents of the invention described above, and therefore the present invention should not be interpreted as being limited to matters described in such drawings.

[0027] Figure 1 schematically illustrates the structure of a coating device according to one embodiment of the present invention.

[0028] Figures 2a to 4 schematically illustrate the structure of a unit according to one embodiment of the present invention.

[0029] Figure 5 is a perspective view of a unit according to one embodiment of the present invention.

[0030] Figures 6 to 10 schematically illustrate a coating process using a coating device to which a coating-bar is applied according to one embodiment of the present invention.

[0031] Fig. 11 schematically illustrates a portion of a coating-bar (200) in which a wire (31) is wound in a spiral shape on the surface of one part (20), and Fig. 12 illustrates a method of applying a coating solution using the same.

[0032] Fig. 13 is a schematic diagram showing a portion of a coating bar (200) having a surface (41) in the form of multiple ring shapes connected together, and Fig. 14 shows a method of applying a coating solution using the same.

[0033]

[0034] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0035]

[0036] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0037]

[0038] In this specification, terms such as "upper," "lower," "left," "right," "inner," and "outer" refer to positions or directions within the referenced drawings and should not be limiting. The terms "inner" and "outer" refer to directions toward or away from the geometric center of the designated device, system, or its components, respectively. These terms include the words listed above, their derivatives, and words of similar meaning.

[0039] In this specification, when it is said that a member is located “on” another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

[0040]

[0041] Throughout this specification, when it is said that a part "includes" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0042]

[0043] <Coating device>

[0044] The present invention provides a coating device.

[0045] Figure 1 schematically illustrates the structure of a coating device according to one embodiment of the present invention.

[0046] According to one aspect of the present invention, a coating device (10) of the present invention includes a coater head (100); a receiving chamber (110) located inside the coater head (100) and containing a coating liquid; and a coating bar (200) that transfers the coating liquid from the receiving chamber (110) onto at least one surface of a substrate (S) transported in one direction. The coating bar (200) is mounted on the coater head (100) so as to be rotatable.

[0047] In one embodiment of the present invention, an ultrasonic generator (not shown) that applies ultrasonic waves to the coating liquid contained in the receiving chamber (110) may be further positioned inside the coater head (100).

[0048] In one embodiment of the present invention, the coating bar (200) transfers the coating liquid from the receiving chamber onto at least one surface of a substrate (S) being transported in one direction. In Fig. 1, the MD direction represents the machine direction.

[0049] The above substrate (S) is illustrated in FIG. 1 for reference, but should not be construed as limiting the coating device (10) of the present invention. The substrate (S) may be a porous polymer substrate for manufacturing a separator for a secondary battery. The coating solution may be a slurry-like coating solution containing a binder polymer, inorganic particles, and a solvent. By coating such a coating solution on at least one surface of the substrate (S), a separator including an inorganic coating layer on the porous polymer substrate can be manufactured. The coating device (10) of the present invention is thus suitable for use in separator coating.

[0050] In one embodiment of the present invention, the coating device (10) can receive a coating liquid from the outside and store the coating liquid in a receiving chamber (110), and the coating liquid contained in the receiving chamber (110) can contact the coating bar (200) so that the coating liquid applied to the coating bar (200) can be transferred onto at least one surface of a substrate (S) to be transported in one direction.

[0051] The coating-bar unit described later in this specification may form a coating-bar alone, or two or more may be assembled into an integral body to form a coating-bar (200). The coating-bar may be rotatably mounted on the coating head.

[0052] In one embodiment of the present invention, the front part of the coater head (100) means the outer surface of the coater head (100) close to before the substrate being transported in one direction comes into contact with the coating-bar (200), and the rear part of the coater head (100) means the outer surface of the coater head (100) close to after the substrate being transported in one direction comes into contact with the coating-bar (200).

[0053]

[0054] <Coating-Bar>

[0055] In the present invention, the coating bar (200) is a modular system including one or more units. The coating bar (200) includes one or more units (210, 220) described below, and the length of the coating bar (200) can be adjusted by combining the units. That is, one unit (210, 220, 230) can be mutually combined with another unit at the end portion to extend the overall length of the coating bar (200). The units can be connected or combined so as to have substantially no play. In the present specification, substantially no play can mean that the interval between the units is 5 mm or less, 3 mm or less, 1 mm or less, 500 μm or less, 300 μm or less, or 100 μm or less. In addition, the coating width can be expanded by the length of the extended coating bar (200). The units included in the coating bar (200) are synchronized and coaxially rotated. In the present invention, when the coating bar (200) includes a plurality of units, the units arranged at both ends of the coating bar (200) may be provided with fasteners (not shown) designed to be mounted on the coating head at the outer end of each unit and to be rotatable.

[0056]

[0057] In one embodiment of the present invention, the unit comprises a first cylindrical part having a large diameter and a second cylindrical part having a small diameter. The first and second parts are connected so as to be coaxially rotatable, with their distal ends being in close contact with each other without any play. The first and second parts are configured to rotate synchronously, and the first and second parts have the same angular velocity during rotation. The first and second parts are connected in a step manner due to the difference in diameter.

[0058]

[0059] In one embodiment of the present invention, the unit may include one or more of the first and second parts. At this time, the first parts may be arranged at each of the two end portions of the unit, and one or more of the second parts may be coupled between the first parts.

[0060]

[0061] Additionally, the unit includes a third cylindrical part having an interior that is hollow. The third part can cover either the first part or the second part and is configured to be movable between the first part and the second part. The third part is configured to rotate in synchronization with the first part and / or the second part. The third part is provided as a tubular part with an inner diameter that is equal to or at least larger than the diameter of the first part and is configured to be slidably movable between the first part and the second part.

[0062] The third part may be provided to have a length equal to or greater than that of the second part so as to cover the entire second part. In one embodiment of the present invention, the coating bar may include the same number of third parts as the first part in at least one unit.

[0063] In one embodiment of the present invention, the first part and the second part may have the same or different lengths. When a single unit includes two or more first parts, each first part may have the same or different lengths. When a single unit includes two or more second parts, each second part may have the same or different lengths.

[0064]

[0065] In one embodiment of the present invention, the first and second parts may each include a fixing member (300) capable of fixing the third part. For example, the fixing member may be retractably provided in the body of each part. That is, the fixing member may be configured to be retracted into the body of each part so as to be flush with the body surface and then protrude outward to support the inner surface of the third part. The end portion of the fixing member that contacts the inner surface of the third part may have elasticity. One or more of the fixing members may be included in each part, and may be configured to be retracted and protruded by mechanical manipulation and / or electrical signals. The number or position of the fixing members is not particularly limited and may be appropriately arranged. By means of the fixing members, the third part may rotate in synchronization with other parts when the coating bar rotates. When the above-mentioned fixed part is introduced, it is preferable that the surface of the fixed part and the surface of each part are substantially uniform and that no step in the coating surface is generated by the fixed part.

[0066]

[0067] Here, the first and third parts may form a coated portion, and the second part may form a non-coated portion. That is, the slurry may be applied to the substrate by moving along the surface of the first and / or third parts in the chamber, and since the second part does not come into contact with the slurry, the slurry is not applied to the substrate surface corresponding to the portion where the second part moves.

[0068] In the present invention, the difference between the outer diameter of the third part and the diameter of the first part may be 20 μm or less. If the difference exceeds 20 μm and is large, the step difference between the third part and the first part may be large, resulting in uneven coating thickness. Meanwhile, the difference between the diameter of the first part and the diameter of the second part may be 10 mm or more. If the difference is small, less than 10 mm, it is difficult to effectively implement the desired level of pattern coating.

[0069]

[0070] In one embodiment of the present invention, one end of the unit may be configured with one or more first parts, and the opposite end may be configured with one or more second parts. At this time, the unit may include one or more third parts that are configured to slide between the first and second parts. The total length of the third part may be equal to or longer than the total length of the second part.

[0071]

[0072] When the third part is slidably moved to cover the second part, the end of the third part may overlap the first part so that the third part may be supported by the first part, if the third part is longer than the total length of the second part. Meanwhile, in one embodiment, the total sum of the lengths of the first part may be equal to or different from the total sum of the lengths of the third part.

[0073]

[0074] Figures 2a, 2b, and 2c illustrate a unit (210) each including a first part (211), a second part (212), and a third part (213) (specific example A). Referring to this, the first (211) and the second parts (212) are connected to enable coaxial rotation, and one third part (213) is provided to enable sliding movement between the first and second parts. Figure 2a illustrates a shape in which the third part covers the second part, Figure 2b illustrates a shape in which the third part moves from the second part to the first part, and Figure 2c illustrates a shape in which the third part covers the first part.

[0075] In one embodiment of the present invention, the length of the third part may be equal to or longer than the length of the second part. The length of the second part may be equal to or different from the length of the first part. The length of the third part and the length of the first part may be equal to or different. In terms of coating surface uniformity, it is preferable that the lengths of the third part and the first part are equal. If the length of the third part is shorter than the length of the first part, when the third part slides toward the first part, a step may be generated at the ends of the third part and the first part, which may deteriorate the coating surface uniformity. However, this may depend on the viscosity and spreadability of the coating liquid. If the viscosity of the coating liquid is low or the spreadability is high, the coating liquid can be applied uniformly even if the step difference between the first and third parts is large.

[0076]

[0077] In one embodiment of the present invention, the unit may have first parts arranged at each of the two ends, and one or more second parts may be connected between the two first parts so as to be synchronously rotatable and coaxial. At this time, one or more third parts may be included that are provided to slide the first and second parts. Here, the sum of the lengths of the third parts may be equal to or longer than the sum of the lengths of the second parts. When the unit includes two third parts, the length of at least one of the third parts may be equal to or longer than the sum of the lengths of the second parts.

[0078]

[0079] Fig. 3 is a schematic diagram of a unit (220) in which a second part (222) is connected between two first parts (221a, 221b) (specific example B). Here, the unit includes a third part (223) covering one of the two first parts, and the length of the third part is equal to or longer than the length of the second part.

[0080]

[0081] Figures 4 and 5 are schematic diagrams illustrating another embodiment of the present invention (specific example C). Figure 4 is a side view, and Figure 5 is a perspective view. Referring to these, a unit (230) is schematically illustrated, in which two second parts (232a, 232b) are connected between two first parts (231a, 231b), and two third parts (233a, 233b) covering each first part are included. Referring to these, each third part is equal to or longer than the length of each adjacent second part. Each third part may be configured to move from both ends to the center to cover the second part. In one embodiment of the present invention, 233a and 233b may have different inner diameters, and when covering the second part, they may overlap and support each other. Additionally, at this time, the third parts (233a, 233b) may overlap the ends of the first parts (231a, 231b) (not shown). The length of the third parts (233a, 233b) may be appropriately adjusted so that such a structure can be implemented.

[0082]

[0083] In one embodiment of the present invention, the coating bar (200) may be configured by combining one or more of the aforementioned units. The coating bar (200) may be formed by interconnecting multiple units while being arranged longitudinally along the width direction of the membrane substrate to be coated, and may have a width corresponding to the entire width of the membrane substrate or a width greater than this.

[0084]

[0085] FIGS. 6 to 10 schematically illustrate a coating bar (200a) configured by connecting three units (230) according to specific example C. In order to clearly show the structure of the coating bar (200), other components of the coating device (10) are indicated by dotted lines. For the purpose of explaining the invention, the unit illustrated on the left side of the drawing is referred to as unit a (230a), the unit illustrated on the right side is referred to as unit b (230c), and the unit positioned between units a and c is referred to as unit b (230b). Here, the first and second modules are illustrated as having the same length, but this is not limited thereto, and the lengths of the first and second modules may be the same or different from each other.

[0086]

[0087] FIG. 6 illustrates a process of applying a coating solution to the surface of a substrate using a coating device having a coating-bar (200a) having such a structure, in which each third part of each unit (230a, 230b, 230c) in the coating-bar (200a) of Specific Example C moves to its corresponding second part to cover the second part (Specific Example C-1). Referring to this, the outer surface of the coating-bar is formed by combining Parts 1 and 3, and the coating layer formed on the surface of the substrate has a width corresponding to the length of the coating-bar, and a coating portion (C1) having a width corresponding to the entire length of the coating-bar is formed. Since Parts 1 and 3 have different diameters, the entire coating-bar may not be perfectly flat and a step may be formed between Parts 1 and 3. However, by controlling the spreadability of the coating solution, the coating surface may be flat without a step.

[0088]

[0089] FIG. 7 illustrates a process of applying a coating liquid to the surface of a substrate using a coating device having a coating-bar (200a) having such a structure, in which the third part of the unit b (230b) in the coating-bar (200a) of Example C covers the first part, and the third part of the unit a (230a) and the unit c (230c) is moved to cover the second part (Example C-2). Referring to this, the unit b has a part 2 with a small diameter exposed, so that the corresponding part is not applied with the coating liquid and is maintained as an uncoated portion (C2), and the coating liquid is applied to both sides of the uncoated portion in the width direction by the units a and c to form a coated portion (C1).

[0090]

[0091] FIG. 8 shows a process of applying a coating liquid to the surface of a substrate using a coating device having a coating-bar (200a) having such a structure, in which the third parts of units a (230a) and c (230b) cover the first part in the coating-bar (200a) of specific example C, and the third part of unit b is moved so as to cover the second part (specific example C-3). Referring to this, the second part of unit b is covered by the third part, so that the coating liquid of the substrate is applied. Meanwhile, the surfaces corresponding to the second parts of units a and c are not applied with the coating liquid and are maintained as an uncoated portion (C2), and the coating liquid is applied to both sides in the width direction of the uncoated portion by the third parts of units a and c, thereby forming a coated portion (C1).

[0092]

[0093] FIG. 9 illustrates a coating device in which a coating-bar (200a) of a specific example C is applied, in which units a and b are moved so that the third part covers the second part, and a coating liquid is applied to the substrate (specific example C-4). Referring to this, units a and b have the second part covered by the third part, so that the coating liquid is applied to the substrate. Meanwhile, the surface corresponding to the second part of unit c is not coated with the coating liquid and is maintained as an uncoated portion, and the coating liquid is applied to both sides of the uncoated portion in the width direction by the third part, thereby forming a coated surface.

[0094]

[0095] FIG. 10 illustrates a coating device having a coating-bar (200a) of a specific example C, in which the third part of one of the units is moved so that it covers the first part and the third part of the other unit covers the second part, and a coating device having such a structure is used to coat a substrate (specific example C-5). Referring to this, a surface corresponding to a portion of the second part that is not covered by the third part in each unit and is exposed is not coated with a coating solution and is maintained as an uncoated portion, and a coating solution is coated on both sides of the uncoated portion in the width direction by the first and third parts to form a coated surface.

[0096]

[0097] Meanwhile, in one embodiment of the present invention, the coating bar (200) may be a wire bar having wires wound on its surface or may have a specific pattern applied thereto. For example, the coating bar (200) may have a Mayer bar shape. The surface pattern may be applied to facilitate uniform application of the coating solution. Alternatively, the coating bar (200) may not have a specific pattern formed on its surface. In the present specification, the surface shape of the coating bar may be determined by the surface shape of each part described below. For example, when each part is prepared in the shape of a wire bar, the coating bar (200) formed by combining them may have the shape of a wire bar.

[0098] Fig. 11 is a schematic diagram showing a portion of a coating bar (200) having a wire (31) wound in a spiral shape on the surface of one part (20), and Fig. 12 shows a method of applying a coating solution using the same. Meanwhile, Fig. 13 is a schematic diagram showing a portion of a coating bar (200) having a surface (41) having a plurality of ring-shaped connections on the surface (20) of each part, and Fig. 14 shows a method of applying a coating solution using the same.

[0099]

[0100] In one embodiment of the present invention, the coating bar is mounted on the coating head (100), coats the slurry on the transported separation membrane, and is configured to be able to control the coating pattern of the slurry coated on the separation membrane.

[0101]

[0102] Meanwhile, in order for the coating liquid to come into contact with the coating bar (200) in the receiving chamber (110), an auxiliary device (not shown) may be additionally provided to push up the coating liquid so that the location where the coating liquid is received is positioned close to the coating bar (200) inside the receiving chamber (110).

[0103]

[0104] In one embodiment of the present invention, the ultrasonic generator (120) is a device capable of generating ultrasonic waves, and there are no limitations on its type and shape.

[0105]

[0106] In one embodiment of the present invention, the ultrasonic generator (120) generates ultrasonic waves to cause vibrations in the solvent of the coating solution, and energy is generated as microbubbles are created and destroyed by the vibrations, and the energy can deagglomerate the agglomerates between the inorganic particles and the binder polymer in the coating solution. The ultrasonic generator (120) can also help to uniformly disperse the solid matter in the coating solution in the solvent. In particular, the ultrasonic generator (120) is configured to be capable of generating ultrasonic waves of a level that can exhibit an inorganic disintegration effect that separates the agglomerated inorganic particles.

[0107]

[0108] Meanwhile, in one embodiment of the present invention, the coating device (1) may further include a coating liquid tank located outside the coater head (100) and supplying the coating liquid to the receiving chamber (110) through a transfer pipe.

[0109]

[0110] In one embodiment of the present invention, the coating device (10) may be positioned on the outer surface of the coater head (100) and may further include a recovery unit (not shown) that coats at least one surface of the substrate (not shown, see 2 of FIG. 1) and transports and receives the remaining coating liquid along the outer surface of the coater head (100). The coater head (100) may have an inclined slope formed on its outer surface. Due to the inclined slope, the remaining coating liquid may flow down the surface of the coater head (100) and be collected in the recovery unit (140).

[0111]

[0112] <Method for manufacturing a separation membrane>

[0113] The present invention can manufacture a separation membrane using a coating bar according to the present invention and a coating device including the coating bar.

[0114]

[0115] The method for manufacturing a separation membrane of the present invention supplies a coating solution containing a binder polymer, inorganic particles, and a solvent to the receiving chamber (110) of a coating device (1) (step S10).

[0116]

[0117] In one embodiment of the present invention, a coating solution may be prepared by adding a binder polymer and inorganic particles to a solvent and mixing them. The solid content of the coating solution may be adjusted to a range of 5 to 70 wt% based on 100 wt% of the coating solution, but is not particularly limited thereto. The viscosity of the coating solution may be within a range of 10 to 50 cps at 25°C, but is not particularly limited thereto. At this time, the viscosity of the coating solution may be measured using a Brookfield viscometer (DV2T viscometer, 1000 rpm, spindle 63) at 25°C, for example. The surface of the coating roller according to the present invention may have fine steps between parts. However, as the coating solution spreads uniformly due to surface tension, it can fill in the fine steps on the roller surface and be evenly distributed. Accordingly, by controlling the concentration and viscosity of the coating solution to ensure appropriate spreadability, a consistent thickness and uniform quality can be maintained. The content of the above solids can be adjusted to an appropriate range considering the spreadability of the coating liquid.

[0118]

[0119] In one embodiment of the present invention, the method of supplying the coating solution to the receiving chamber (110) is not limited, but for example, the coating solution may be supplied by pouring it into the receiving chamber (110), or the prepared coating solution may be first supplied to the coating solution tank (200), and then the coating solution may be supplied to the receiving chamber (110) through a separate transport conduit (210).

[0120]

[0121] In one embodiment of the present invention, the binder polymer can improve the mechanical properties such as flexibility and elasticity of the finally formed separator, and faithfully performs the role of a binder that connects and stably fixes inorganic particles, thereby contributing to preventing deterioration of the mechanical properties of the separator. The glass transition temperature (T) of the binder polymer g ) can exist within the range of -200 to 200℃.

[0122] In addition, the binder polymer does not necessarily need to have ion-conducting ability, but if a polymer having ion-conducting ability is used, the performance of the lithium secondary battery can be further improved. Therefore, the binder polymer may have a high dielectric constant as much as possible. In fact, since the degree of salt dissociation in the electrolyte depends on the dielectric constant of the electrolyte solvent, the higher the dielectric constant of the binder polymer, the better the degree of salt dissociation in the electrolyte. The dielectric constant of the binder polymer can be used in the range of 1.0 to 100 (measurement frequency = 1 kHz), and in particular, can be 10 or more.

[0123] In one embodiment of the present invention, the binder polymer can exhibit a high degree of swelling by being gelled when impregnated with a liquid electrolyte. The solubility index of the binder polymer, i.e., the Hildebrand solubility parameter, is 15 to 45 MPa. 1 / 2 or 15 to 25 MPa 1 / 2 and 30 to 45 MPa 1 / 2 It may be within a range. In one embodiment of the present invention, when hydrophilic polymers having a large number of polar groups are used more than hydrophobic polymers such as polyolefins, the solubility index range described above can be satisfied. In this case, when the solubility index is below the lower limit or exceeds the upper limit of the above-described range, swelling by a typical battery liquid electrolyte may be difficult.

[0124] In one embodiment of the present invention, the inorganic particles are filled and in contact with each other and are bound to each other by the binder polymer, thereby forming an interstitial volume between the inorganic particles, and the interstitial volume between the inorganic particles may become an empty space to form pores. The binder polymer may attach the inorganic particles to each other so that the particles can maintain a state of being bound to each other, for example, the binder polymer may connect and fix the inorganic particles. In addition, the pores of the separator are pores formed by the interstitial volume between the inorganic particles becoming an empty space, and this may be a space defined by the inorganic particles substantially meeting each other in a closed packed or densely packed structure by the inorganic particles.

[0125] In one embodiment of the present invention, any binder polymer commonly used in the relevant technical field can be used without limitation. The above binder polymers include, for example, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl Cellulose (carboxyl methyl cellulose), or two or more of these.

[0126] At this time, the binder polymer may be a particulate binder or a soluble binder. The particulate binder is a binder polymer that does not dissolve in a solvent. The binder polymer is a soluble binder, meaning that the binder polymer dissolves in a solvent. At this time, the solvent may be an aqueous solvent or an organic solvent.

[0127]

[0128] In one embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention can be used within the operating voltage range of the applied electrochemical device (e.g., Li / Li). + There are no particular limitations as long as no oxidation and / or reduction reaction occurs at a voltage of 0 to 5 V as a standard. In particular, when using inorganic particles with a high dielectric constant as inorganic particles, it can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0129] For the reasons mentioned above, it is preferable that the inorganic particles include high-k inorganic particles having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, TiO2 or mixtures thereof.

[0130] In addition, inorganic particles having lithium ion transfer capability, i.e., inorganic particles containing lithium element but having the function of transferring lithium ions without storing lithium, can be used. Non-limiting examples of inorganic particles having lithium ion transfer capability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li). x Ti y (PO4)3, 0 < x <2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z(PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), 14Li2O-9Al2O3-38TiO2-39P2O5, etc. (LiAlTiP) x O y Series Glass (0 <x < 4, 0 < y < 13), 리튬란탄티타네이트(Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 Lithium germanium thiophosphate (Li) such as S4 x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li 3 N ), etc. x N y , 0 < x <4, 0 < y < 2), SiS2 series glasses such as Li3PO4-Li2S-SiS2 (Li x Si y S z , 0 < x < 3, 0 <y < 2, 0 < z < 4), LiI-Li2S-P2S5등과 같은 P2S5계열 글래스(Li x P y S z , 0 < x < 3, 0< y < 3, 0 < z < 7) or mixtures thereof.

[0131] In addition, the average particle diameter (D) of inorganic particles (single particles) 50 ) has no special limitations, but in order to form a coating layer of uniform thickness and have an appropriate porosity, it is preferably in the range of 0.1 ㎛ to 1.5 ㎛. If the average particle diameter of the inorganic particles is less than the lower limit, dispersibility may be reduced, and if it exceeds the upper limit, the thickness of the inorganic coating layer formed may increase.

[0132] In one embodiment of the present invention, the inorganic particles may be included in an amount of 50 wt% or more based on 100 wt% of the solid content of the coating liquid.

[0133]

[0134] In one embodiment of the present invention, the solvent may be an aqueous solvent or an oil-based solvent.

[0135] In one embodiment of the present invention, the aqueous solvent may be water or an aqueous solvent containing water. Furthermore, when drying speed and temperature are limited, methanol, ethanol, isopropyl alcohol, or the like, which have a lower boiling point than water, may be used together.

[0136] In one embodiment of the present invention, the organic solvent is cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene, xylene and ethylbenzene; ketones such as acetone, ethyl methyl ketone, diisopropyl ketone, cyclohexanone, methylcyclohexane and ethylcyclohexane; chlorinated aliphatic hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride; esters such as ethyl acetate, butyl acetate, gamma butyrolactone and ε-caprolactone; acylonitrile such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether; alcohols such as methanol, ethanol, isopropanol, ethylene glycol and ethylene glycol monomethyl ether; amides such as N-methylpyrrolidone and N,N-dimethylformamide. , and the organic solvent may include acetone in consideration of the advantage in the drying process.

[0137] In one embodiment of the present invention, the organic solvent may be used alone, or a mixed solvent of two or more thereof may be used. Among these, solvents with low boiling points and high volatility are particularly preferred, as they can be removed in a short period of time and at low temperatures. Specifically, acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene, or N-methylpyrrolidone, or a mixed solvent thereof, are preferred.

[0138]

[0139] Next, the coating liquid is transferred onto at least one surface of the substrate to be transported in one direction (step S20).

[0140] The above substrate may be a porous polymer substrate for manufacturing a separator for a secondary battery. The porous substrate may electrically insulate the positive and negative electrodes, prevent short circuits due to electrode contact, and provide a path for lithium ions to move. For example, the porous substrate may be a polymer film or nonwoven fabric comprising one or more polymer resins selected from the group consisting of polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalene, but is not limited thereto. The porous substrate may be formed of a single layer of polymer film or nonwoven fabric, but is not limited thereto, and may be formed of multiple layers.

[0141]

[0142] Meanwhile, in one embodiment of the present invention, a step of applying ultrasonic waves to the coating solution may be performed prior to applying the coating solution. There are no limitations on the method of applying ultrasonic waves to the coating solution, but for example, ultrasonic waves may be applied to the coating solution by the ultrasonic generator (not shown) described above.

[0143]

[0144] The present invention may be implemented independently of each of the aforementioned embodiments. Furthermore, the present invention may be implemented by combining two or more of the aforementioned embodiments.

[0145]

[0146] [Explanation of symbols]

[0147] 10: Coating device, 2: Substrate, 100: Coater head, 110: Receiving chamber,

[0148] 200, 200a: Coated-bar

Claims

1. For a coating-bar comprising one or more units, The above unit comprises a first part, a second part and a third part of a cylindrical shape. The above first and second parts have different diameters. The first and second parts are interconnected so that the distal ends can rotate coaxially, The third part is a coating-bar having a hollow interior and a longitudinally penetrable structure, and is mounted to cover the outer side of at least one of the first and second parts and to be slidably moved on the outer side of the first and second parts.

2. In paragraph 1, The above unit is a coating-bar comprising one or more of each of the first, second and third parts.

3. In paragraph 1, The above first part is a coating-bar having a larger diameter than the second part.

4. In paragraph 1, A coating bar wherein the difference in diameter between the first part and the second part is 10 mm or more.

5. In paragraph 1, A coating-bar having an inner diameter of the above three parts that is equal to or greater than the outer diameter of the above first part.

6. In paragraph 1, A coating-bar in which the total length of the third part in the above unit is equal to or greater than the total length of the second part.

7. In paragraph 1, The above unit is a coating-bar in which a first part is arranged at each of the two ends, and one or more second parts are connected so as to be rotatable coaxially between the two first parts.

8. In paragraph 7, A coating-bar having two second parts connected between two first parts, and two third parts covering each first part, each third part having a length equal to or longer than the length of each adjacent second part.

9. In paragraph 1, A coating-bar, wherein at least one of the first part and the second part includes a fixing member capable of supporting a third part.

10. In paragraph 9, The above-mentioned fixed part is a coating-bar configured to be inserted into the inside of the body of each part so as to be flush with the body surface and then protrude outward to support the inner surface of the third part.

11. A coating device comprising a coating bar according to any one of claims 1 to 10.

12. In paragraph 11, A coating device, wherein the coating device further includes a coater head and a receiving chamber located inside the coater head and receiving a coating liquid, and a coating bar is installed so as to be rotatable.

13. In paragraph 12, A coating device further comprising an ultrasonic generator located inside the coater head and / or inside the receiving chamber, the ultrasonic generator applying ultrasonic waves to the coating liquid received in the receiving chamber.

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