Dispensing coating device for lithium battery separator

Abstract

The present application relates to the technical field of lithium battery diaphragm preparation, and particularly relates to a lithium battery diaphragm dispensing coating device. The present application mainly comprises a coating transfer device, a feed amount controller and a flat bottom roller, wherein the coating transfer device comprises a glue accommodating device and a relief roller, the glue accommodating device is provided with a glue accommodating groove for accommodating glue, and the roller surface of the relief roller is provided with a transfer relief point; the relief roller is located between the glue accommodating device and the flat bottom roller, the transfer relief point is inserted into the glue accommodating groove at the contact position of the relief roller and the glue accommodating device; the feed amount controller is used for detecting and adjusting the feed amount of the transfer relief point inserted into the glue accommodating groove; the flat bottom roller is located on the lower side of the relief roller, and a film passing gap for passing the coating film is arranged between the flat bottom roller and the relief roller. The thickness of the coating layer formed by using the device is large, and the thickness and coverage control of the glue point are simple and convenient.

Description

Technical Field

[0001] This invention relates to the field of lithium battery separator preparation technology, and in particular to a lithium battery separator dispensing and coating device. Background Technology

[0002] In the battery industry, the manufacturing of separators and electrodes; in the sanitary packaging industry, the manufacturing of breathable membranes and non-woven fabrics; and in the electronics industry, the manufacturing of protective films, coating technology is required to form a non-full-coverage coating layer.

[0003] Taking the preparation of separators in the battery industry as an example, lithium batteries today not only require good thermal stability and adhesion between the separator and the electrode, but also fast charging performance. By using a non-full-coverage coating adhesive layer, the absence of polymer adhesive dots and pores can enable the effective transport of lithium ions, improve the lithium ion conductivity of the separator, thereby improving the charge and discharge performance of the lithium battery and extending its cycle life.

[0004] In existing technologies for preparing lithium-ion battery separators, the non-full-coverage coating techniques generally include two types: PVDF (polyvinylidene fluoride, a highly non-reactive thermoplastic fluoropolymer) agglomeration shrinkage coating films and PVDF "island" sprayed films. The former utilizes the hydrophobicity of PVDF on the separator surface, adjusting the slurry tension to form agglomerates. The slurry shrinks rapidly upon contact with the membrane surface, preventing continuous formation; however, due to the slurry-based adjustment, its stability is poor. The latter involves high-speed rotation and throwing of PVDF onto the separator surface, forming island-like structures to anchor the electrodes, but the shapes are irregular. Therefore, existing non-full-coverage coating techniques in lithium-ion battery separator preparation all have various problems.

[0005] As mentioned above, the non-full-coverage coating adhesive layer used in the existing lithium battery separator preparation cannot precisely control the size, distance, and aggregation state of each adhesive dot. Therefore, the resulting discrete adhesive film layer affects both production quality control and subsequent winding quality. To address this, the inventors of this application have developed a non-full-coverage coating separator preparation scheme (which should not be considered entirely prior art) that can form a flat, uniformly sized local coating structure, thereby achieving a uniform "dot-like" coating film of PVDF.

[0006] like Figure 1As shown, firstly, the recessed holes or grooves 011 on the surface of the anilox roller 01 are filled with coating adhesive to form a liquid film layer of uniform thickness. Then, the liquid film layer is transferred to the transfer surface of the protrusions 021 on the letterpress roller 02 during the contact with the anilox roller 01, and during the transfer process, the transfer surface of the protrusions 021 is in tangential contact with the surface of the anilox roller 01. Finally, the transfer surface of the protrusions 021 on the letterpress roller 02 is squeezed by the flat bottom roller 03 to transfer the liquid film layer on the transfer surface of the protrusions 021 to the diaphragm 04 that passes between the flat bottom roller 03 and the letterpress roller 02 and moves in direction j, thereby forming a uniform "dot-like" coating layer on the side of the diaphragm 04 facing the letterpress roller 02.

[0007] The inventors of this application have discovered that, although the above-mentioned uniform "dot-like" coating method for preparing the diaphragm can form a flat and uniformly sized local coating structure on the diaphragm, it can only form a thin liquid film layer (e.g., the coating film thickness is less than 5 μm), and cannot meet the requirement of a thicker coating film (e.g., the coating film thickness is more than 10 μm). In addition, different types of diaphragms require different liquid film thicknesses, and existing solutions generally can only adjust the dot coating thickness by changing different versions of gravure rollers, but this method is costly, cumbersome, and time-consuming. Summary of the Invention

[0008] To meet the production needs of preparing thicker coating layers on coated films in the battery, sanitary packaging, and electronics industries, this invention proposes a lithium battery separator dispensing and coating apparatus. This apparatus includes a coating transfer device, a feed rate controller, and a flat bottom roller. The coating transfer device comprises a material receiving device and a letterpress roller. The material receiving device has a material-containing groove for storing and containing the material. The letterpress roller has transfer protrusions on its surface, which are adapted to be inserted into the material-containing groove at corresponding positions on the material receiving device to transfer the separator coating. The separator coating forms coating droplets covering the transfer end faces of the transfer protrusions. The flat bottom roller rotates in the opposite direction to the material receiving device, driving the coated film to move, causing the coating droplets on the transfer protrusions to cover the coated film and form a non-fully covered coating layer. Preferably, the material receiving device is an anilox roller, a texturing roller, or a smooth roller.

[0009] Furthermore, when using this lithium battery separator dispensing and coating device to apply coating material onto the coating film to form a coating layer, the coating material in the hopper is first transferred to the receiving groove on the anilox roller using an anilox roller, and a liquid film layer of uniform thickness is formed in the receiving groove on the roller surface of the anilox roller; then, by rotating the letterpress roller and the anilox roller, the transfer bump on the letterpress roller is inserted into the receiving groove on the anilox roller and leaves the receiving groove as the letterpress roller and the anilox roller rotate, while the tension of the coating material itself is used to carry the coating material out from the receiving groove, and an approximately spherical or ellipsoidal coating material droplet is formed on the transfer end of the transfer bump; finally, when the transfer bump with the coating material droplet is rotated to face the coating film passing through the film gap, the coating material droplet is mainly transferred and dripped onto the coating film under the action of tension difference, thereby forming a non-full coverage coating layer on the coating film; It should be emphasized that the coating adhesive droplets are mainly transferred and coated by utilizing the tension difference between the letterpress roller and the coating film. The greater the tension difference, the better the coating transfer effect. As those skilled in the art also know, the gravity of the coating adhesive droplets themselves and the centrifugal force generated by the rotation of the letterpress roller also play a certain role in their transfer and coating onto the coating film.

[0010] Furthermore, the device also includes a feed rate controller and a flat bottom roller. The feed rate controller is used to detect and adjust the feed rate at which the transfer protrusion on the letterpress roller is inserted into the material receiving groove. The flat bottom roller is located below the letterpress roller, and a film-passing gap is provided between the flat bottom roller and the letterpress roller for the coating film to pass through. When using this dispensing coating apparatus to apply coating material onto a coating film to form a coating layer, the coating material in the hopper is first transferred to the receiving groove on the anilox roller using an anilox roller, forming a uniform liquid film layer in the receiving groove on the roller surface of the anilox roller. Then, by rotating the letterpress roller and the anilox roller, the transfer bumps on the letterpress roller are inserted into the receiving grooves on the anilox roller and leave the receiving grooves as the letterpress roller and the anilox roller rotate. At the same time, the tension of the coating material itself carries the coating material out of the receiving grooves, forming approximately spherical or ellipsoidal coating material droplets on the transfer ends of the transfer bumps. Finally, when the transfer bumps with coating material droplets are rotated to face the coating film passing through the film-passing gap, the coating material droplets mainly drip onto the coating film under the action of tension difference, thereby forming a non-full-coverage coating layer on the coating film. Furthermore, during the preparation process, the thickness of the resulting coating layer is adjusted and controlled by regulating the feed rate of the transfer protrusions on the letterpress roller into the material-containing grooves on the anilox roller. Experiments show that the coating layer thickness formed on the coating film using the lithium battery separator dispensing and coating device of this invention ranges from 2μm to 30μm. Compared to the coating layer thickness of less than 5μm formed by existing technologies, the coating layer formed by this invention has a larger thickness, and thickness control is simple and convenient.

[0011] Furthermore, the lithium battery separator dispensing and coating apparatus can also be equipped with a coating device, which abuts against the adhesive receiving device, so that the coating material forms a liquid film layer of uniform thickness on the surface of the adhesive receiving device. Preferably, the coating device includes a roller or a scraper. When a roller is used, the roller is close to the roller surface of the anilox roller and contacts the coating adhesive on the roller surface of the anilox roller, squeezing and removing excess coating adhesive. During the rotation of the anilox roller, a liquid film layer of uniform thickness is formed in the mesh of the anilox roller. When a scraper is used, the scraper is close to the roller surface of the anilox roller. During the rotation of the anilox roller, the scraper scrapes the coating material on the roller surface of the anilox roller to remove excess coating adhesive, forming a liquid film layer of uniform thickness in the mesh of the anilox roller.

[0012] Preferably, the ratio Q of the inner diameter d1 of the material-containing groove to the diameter d2 of the transfer end face of the transfer protrusion is ≥1.5. This ensures that the area of ​​the transfer end face of the transfer protrusion is much smaller than the cross-sectional area of ​​the material-containing groove, facilitating the insertion of the transfer end face of the transfer protrusion into the material-containing groove of the anilox roller. The tension of the coating material allows it to adhere to the transfer end face of the transfer protrusion, forming spherical or ellipsoidal coating droplets. These coating droplets do not compress the coating film during the transfer process; instead, they are deposited onto the coating film primarily through the tension difference between the anilox roller and the coating film, which are made of different materials. Further, the transfer end face of the transfer protrusion is circular, with a diameter d2 ranging from 20 μm to 1 mm. When the transfer protrusion is inserted into the material-containing groove, the distance L between the transfer end face and the bottom of the groove ranges from 20 μm to 250 μm. Thus, when using the lithium battery separator dispensing and coating apparatus of the present invention to form a non-full-coverage coating layer on the coating film, the transfer of the coating material can be avoided due to the transfer end face of the transfer protrusion being too small or too large. Simultaneously, the height of the coating material droplets formed on the transfer protrusion can be adjusted by changing the depth of the transfer protrusion inserted into the material-containing groove, i.e., the distance L between the transfer end face and the bottom of the material-containing groove. Furthermore, the thickness of the coating layer can be adjusted according to the height of the coating material droplets. Therefore, when using the dispensing and coating apparatus of the present invention to form a non-full-coverage coating layer on the coating film, it is convenient to transfer the coating material on the anilox roller and also convenient for the coating operator to control the thickness of the coating layer.

[0013] Preferably, the transfer protrusion is a conical truncated pyramidal structure with an inwardly concave busbar, a conical truncated pyramidal structure with an outwardly convex busbar, a conical truncated pyramidal structure, or a stepped truncated pyramidal structure. The stepped truncated pyramidal structure includes a connecting base and a transfer protrusion, and the cross-sectional area of ​​the transfer protrusion is smaller than the cross-sectional area of ​​the connecting base. Further, the transfer protrusion is a cylindrical structure, and the connecting base is a conical truncated pyramidal structure. The height h1 of the cylindrical structure is ≤200μm, and the ratio N of the height h1 to the diameter d2 of the transfer end face is ≤2.5. This avoids the transfer protrusion from being too slender during the transfer of the adhesive, which could affect the transfer effect and consequently the subsequent coating effect.

[0014] Preferably, the feed rate controller can be a grating ruler or other high-precision measurement method. Using a grating ruler as the feed rate controller simplifies installation and operation, provides high detection and control accuracy, and allows coating operators to easily control the thickness of the coating layer.

[0015] The present invention has the following advantages:

[0016] When using this invention to form a non-full-coverage coating layer on a coating film, the thickness of the liquid film layer formed by the coating adhesive in the material-holding groove on the anilox roller is uniform, resulting in a stable and uniform coating layer thickness. During the transfer of the coating adhesive, the transfer protrusions on the letterpress roller are inserted into the material-holding groove on the anilox roller. The tension of the coating adhesive carries it out of the groove and forms a coating adhesive droplet on the transfer end of the transfer protrusion, facilitating the transfer of the coating adhesive. Simultaneously, according to the coating requirements, the feed rate controller adjusts the feed rate of the transfer protrusions into the material-holding groove, facilitating the control of the height of the formed coating adhesive droplet and thus the control of the coating layer thickness. During the movement of the coating film, the coating adhesive droplets on the transfer bumps are applied to the coating film. The coating adhesive forms coating dots on the coating film mainly through the tension difference between the coating rollers made of different materials and the coating film. This avoids the coating adhesive droplets being compressed during the coating process, thus ensuring the thickness of the coating layer. At the same time, the area of ​​the coating dots can be appropriately increased by using the coating adhesive located on the side of the transfer bumps, thereby increasing the coverage of the coating layer on the coating film. In the field of lithium battery separator preparation, this coating method has not yet been found to be applied to the production of lithium battery separators. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation apparatus used in existing methods for preparing non-full-coverage coating layers;

[0018] Figure 2A schematic diagram illustrating the preparation of a thin, non-full-coverage coating layer;

[0019] Figure 3 A schematic diagram illustrating the preparation of a relatively thick, non-full-coverage coating layer;

[0020] Figure 4 This is a schematic diagram of the lithium battery separator dispensing and coating device of the present invention;

[0021] Figure 5 A schematic diagram of a dispensing and coating device including a dispensing control unit during dispensing;

[0022] Figure 6 for Figure 4 The diagram shows the structure of the transfer bumps in the lithium battery separator dispensing and coating device. Figure 6 (a) is a structural diagram of the transfer convex point of the conical frustum structure with the busbar concave; Figure 6 (b) is a schematic diagram of the transfer protrusion of the stepped platform structure; Figure 6(c) is a schematic diagram of the transfer protrusion of the conical platform structure with outward convexity of the generatrix; Figure 6 (d) is a schematic diagram of the transfer protrusion of the conical frustum structure;

[0023] Figure 7 for Figure 6 The front view diagram of the transfer convex point shown is as follows, Figure 6 (a) is a front view schematic diagram of the transfer convex point of the conical frustum structure with the busbar concave; Figure 6 (b) is a front view schematic diagram of the transfer protrusion of the stepped platform structure; Figure 6 (c) is a front view schematic diagram of the transfer convex point of the conical frustum structure with outward convexity of the busbar; Figure 6 (d) is a front view schematic diagram of the transfer convex point of the frustum structure;

[0024] Figure 8 for Figure 6 The diagram shown is a front view of the transfer bumps with adhesive droplets applied. Figure 6 (a) is a front view of the transfer protrusion of the concave cone structure with adhesive droplets. Figure 6 (b) is a front view of the transfer protrusion of the stepped platform structure with adhesive droplets applied; Figure 6 (c) is a front view of the transfer protrusion of the conical frustum structure with adhesive droplets applied; Figure 6 (d) is a front view of the transfer protrusion of the truncated cone structure with a drop of adhesive coating;

[0025] Figure 9 This is a schematic diagram of the coating layer prepared using the dispensing and coating device of the present invention, with the transfer protrusion being a conical truncated structure with the busbar recessed.

[0026] The numbers in the diagram are: 01-Anilox roller, 011-Groove, 02-Relief roller, 021-Raised dot, 03-Flat bottom roller, 04-Dip membrane, 05-Coating layer;

[0027] 1-Anilox roller, 11-Material groove, 2-Relief roller, 3-Flat bottom roller, 31-Film threading gap, 4-Coating film, 5-Second fine-tuning platform, 6-Second feed rate controller, 7-First fine-tuning platform, 8-First feed rate controller, 9-Coating adhesive drop, 9-Coating point;

[0028] 21-Transfer protrusion, 211-Transfer end face, 2101-Connecting base, 2102-Transfer boss. Detailed Implementation

[0029] As described in the background art, in the preparation scheme of the non-full-coverage coated diaphragm initially studied by the inventors of this application, although it is possible to form a flat and uniformly sized local coating structure on the diaphragm, it can only form a thin liquid film layer (for example, the thickness of the coating film is less than 5 μm), which cannot meet the preparation requirements of a thicker coating film (for example, the thickness of the coating film is more than 10 μm).

[0030] Therefore, after repeated experiments and in-depth research, the inventors of this application discovered that the initial non-full-coverage coating membrane preparation scheme mainly borrowed technical concepts from printing technology. To ensure that a controllable liquid film layer is formed on the transfer surface of the protrusions 021 on the letterpress roller 02 during the transfer process, the area of ​​the transfer surface of the protrusions 021 is much larger than the area of ​​the recessed holes or grooves 011 on the anilox roller 01; that is, the area of ​​the transfer surface of the protrusions 021 is much larger than the area of ​​the liquid film layer formed within the recessed holes or grooves 011 on the anilox roller 01. However, the inventors of this application realized that this is a significant reason why this preparation scheme makes it difficult to form a thicker coating film, as detailed below.

[0031] Figure 2-3 These are schematic diagrams illustrating the preparation of thin and thick coating layers during the research and development process. Figure 2 As shown, when using the bump 021 for coating droplet application, only a small amount of coating can be obtained through the bump 021. The area of ​​the coating droplet is the same as the transfer surface size of the bump 021. Therefore, only a coating layer 05 with a thickness of less than 10 μm can be formed on the diaphragm 04; Figure 3 As shown, since the liquid film layer is transferred from the letterpress roller 02 to the diaphragm 04 by pressing, the liquid film layer will be flattened during the transfer process, especially when the thickness of the liquid film layer is large, such as exceeding 5μm, forming a shape on the diaphragm 04 as shown in the figure. Figure 3 The coating layer 05 shown has a depression in the middle, and its thickness is extremely difficult to control or even impossible to form.

[0032] It should be noted that the above-mentioned dispensing and coating scheme is not prior art, but only a specific implementation method in the research and development process of the inventors of this application. Therefore, it is unlikely that a person skilled in the art would realize the existence of the above-mentioned technical problem, that is, the discovery of the above-mentioned technical problem is non-obvious to a person skilled in the art.

[0033] As analyzed above, in the initial research on the preparation scheme of non-full-coverage coated diaphragms, during the coating process, on the one hand, because the area of ​​the raised dots on the letterpress roller is much larger than the area of ​​the recessed holes or grooves on the anilox roller, the raised dots can only obtain the coating material on the anilox roller by contacting it. The raised dots cannot pick up larger coating droplets, so only a thin liquid film layer can be formed during dot coating. On the other hand, even if a larger amount of coating material is obtained by changing the gravure roller (anilox roller), it is still difficult to ensure a certain thickness when transferring the coating material from the letterpress roller to the diaphragm to form coating dots (or "coating dots") by imprinting.

[0034] To address this issue, the inventors of this application propose a technical solution that can solve the above-mentioned problems. By changing the shape of the protrusions on the letterpress roller, it is made to insert into the grooves of the gravure roller (anilox roller) to obtain more adhesive. The adhesive on the protrusions is then applied to the coating film by dripping, and the coating points that constitute the coating film are formed on the coating film mainly by the tension difference between the adhesive and the different materials.

[0035] Furthermore, in response to the problem that "different types of diaphragms require different liquid film thicknesses, and existing technologies can only adjust the thickness of the dot coating by replacing different versions of gravure rollers, which is costly, cumbersome, and time-consuming," the inventors of this application have further proposed adjusting and controlling the thickness and shape of the adhesive dots formed by the droplets of coating adhesive onto the coating film by adjusting the feed amount of the protrusions on the letterpress roller into the grooves of the gravure roller (anilox roller) and adjusting the distance between the letterpress roller and the coating film.

[0036] The embodiments of this invention are illustrated using the dispensing and coating process for preparing lithium battery separators as an example. Those skilled in the art will understand that the dispensing and coating apparatus and method of this invention are not only applicable to the preparation of lithium battery separators, but also applicable to the preparation of related film layers in other industries (such as the manufacturing of breathable films and non-woven fabrics in the sanitary packaging industry and the manufacturing of protective films in the electronics industry).

[0037] like Figure 4As shown, the dispensing and coating apparatus provided in this embodiment of the invention includes an anilox roller 1 (adhesive material receiving device), a letterpress roller 2, a feed rate controller (not shown in the figure), and a flat bottom roller 3. The letterpress roller 2 is located between the anilox roller 1 and the flat bottom roller 3, and the flat bottom roller 3 is located below the letterpress roller 2. A film-passing gap 31 is provided between the flat bottom roller 3 and the letterpress roller 2 for the coating film 4 to pass through. The anilox roller 1 has a material-receiving groove 11 on its surface for receiving the coating adhesive. The material-receiving groove 11 is a circular groove and is evenly distributed on the surface of the anilox roller 1. When the coating adhesive is applied to the surface of the anilox roller 1, excess coating adhesive on the surface of the anilox roller 1 can be removed by squeezing or scraping, forming a liquid film layer of uniform thickness (not shown in the figure) within the mesh. The surface of the letterpress roller 2 is provided with transfer protrusions 21, and at the contact position between the letterpress roller 2 and the anilox roller 1, the transfer protrusions 21 are inserted into the corresponding material-receiving grooves 11 on the anilox roller 1. Thus, when the surface of the anilox roller 1 is coated with a coating material, the letterpress roller 2, rotating in the opposite direction to the anilox roller, uses the transfer protrusions 21 inserted into the material-receiving grooves 11 to carry out the coating material from the grooves 11, forming spherical or ellipsoidal coating material droplets 09 at the transfer end face 211 of the transfer protrusions 21. Preferably, when the transfer protrusions 21 on the letterpress roller 2 are inserted into the material-receiving grooves 11 on the anilox roller 1 to transfer the coating material, the distance L between the transfer end face 211 of the transfer protrusions 21 and the bottom of the material-receiving groove 11 is in the range of 20-250 μm. Thus, when using the lithium battery separator dispensing and coating apparatus of the present invention to coat a non-fully covered coating layer on the coating film, the height of the coating material droplet 09 formed on the transfer protrusion 21 can be adjusted by adjusting the depth of the transfer protrusion 21 inserted into the material-containing groove 11, i.e., the value of the distance L between the transfer end face 211 of the transfer protrusion 21 and the bottom of the material-containing groove 11. The height of the coating material droplet 09 refers to the vertical distance from the farthest point of the coating material droplet 09 from the transfer end face 211 of the transfer protrusion 21 along the central axis direction of the transfer protrusion 21. Therefore, the thickness of the coating layer formed by coating can be adjusted according to the height of the coating material droplet 09, thereby facilitating the coating operator to control the thickness of the coating layer formed by coating.

[0038] Figure 5The dispensing and coating control device included in the dispensing and coating apparatus mainly includes: a first fine-tuning platform 7, a first feed rate controller 8, a second fine-tuning platform 5, a second feed rate controller 6, a wear detection device (not shown in the figure), and first and second drive control devices (not shown in the figure). The second drive control device is adapted to control the gravure roller 1 and the letterpress roller 2 to rotate in opposite directions, so that the transfer bumps 21 are sequentially inserted into the material receiving groove 11, and the coating adhesive in the material receiving groove 11 is carried out to form coating adhesive droplets 09 covering the transfer end face 211 of the transfer bumps; the second feed rate controller 6 is adapted to detect the transfer bumps 21. The feed amount is inserted into the material container groove 11 suitable for containing the coating material, and the second fine-tuning platform 5 is controlled to adjust the feed amount according to the coating requirements. The second display and storage device (not shown in the figure) displays and stores the value of the adjusted feed amount. The shape of the coating material droplet 09 corresponds to the adjusted feed amount. The material container groove 11 is provided on the gravure roller 1 included in the dispensing coating device. The gravure roller 1 is provided on the second fine-tuning platform 5. The feed amount controller includes a displacement sensor and a grating ruler. The dispensing and coating apparatus includes a letterpress roller 2 mounted on a first fine-tuning platform 7. A wear detection device detects the wear value of the transfer protrusion 21 and sends the wear value to a first feed rate controller 8. The first feed rate controller 8 is adapted to detect the distance between the transfer protrusion 21 on the letterpress roller 2 and the flat bottom roller 3, and controls the first fine-tuning platform 7 to move according to the coating requirements and wear level to adjust the distance between the transfer protrusion 21 on the letterpress roller 2 and the flat bottom roller 3. A first display and storage device (not shown in the figure) displays and stores the value of the adjusted distance. A first drive control device is adapted to control the drive flat bottom roller 3 to rotate in the opposite direction relative to the letterpress roller 2, thereby moving the coating film 4. The coating adhesive droplets 09 coated on the transfer end face 211 of the transfer protrusion 21 are dripped onto the coating film 4 by the tension difference to form coating dots 9 on the coating film 4. The shape of the coating dots 9 corresponds to the adjusted distance between the transfer protrusion 21 and the flat bottom roller 3. The shape of the coating dots 9 includes at least one of diameter and height.

[0039] It should be noted that, due to long-term use, the diameter of the raised dots on the letterpress roller may increase, affecting the effect of the coating after the diaphragm is applied. If the wear reaches a certain level and the letterpress roller needs to be replaced, the cost increases. In this embodiment, by detecting the wear degree of the transfer raised dots and controlling the movement of the first fine-tuning platform according to the coating requirements and wear degree, the distance between the transfer raised dots on the letterpress roller and the flat bottom roller is adjusted. This ensures that the shape of the coating dots formed on the coating film maintains the expected effect, avoiding the increased cost caused by the need to replace the letterpress roller due to wear and deviation in the existing technology.

[0040] The specific process of forming a coating layer on the coating film using the above-mentioned dispensing and coating control device is as follows:

[0041] First, drive the gravure roller 1 and the letterpress roller 2 to rotate in opposite directions, so that the transfer bumps 21 are inserted into the material receiving groove 11 in sequence, and the coating adhesive in the material receiving groove 11 is carried out. Due to the difference in adhesive viscosity and tension, coating adhesive droplets 09 are formed on the transfer end face 211 of the transfer bumps 21.

[0042] Secondly, the feed amount of the transfer protrusion 21 inserted into the material container groove 11 suitable for accommodating the coating material is detected and adjusted according to the coating requirements. The value A of the adjusted feed amount is displayed and stored. The diameter and height of the coating material droplet 09 correspond to the adjusted feed amount. The material container groove 11 is set on the gravure roller 1 included in the dispensing coating device.

[0043] Finally, the wear value of the transfer bump 21 is detected. Based on the coating requirements and the wear value, the distance between the transfer bump 21 on the letterpress roller 2 and the flat bottom roller 3 in the dispensing and coating device is detected and adjusted. The adjusted distance value B is displayed and stored. The coating material droplet 09 covered on the transfer end face 211 of the transfer bump 21 is dripped onto the coating film 4 by the tension difference, so as to form a first coating material droplet with a height of 1μm-50μm and a diameter of 50μm-1000μm on the coating film 4. The diameter and height of the coating point 9 correspond to the adjusted distance between the transfer bump 21 and the flat bottom roller 3.

[0044] like Figure 6 , 7As shown in Figure 8, the transfer bump 21 can be a conical truncated pyramid structure with an inward concave busbar, a conical truncated pyramid structure with an outward convex busbar, a conical truncated pyramid structure, or a stepped truncated pyramid structure. Preferably, the transfer end face 211 of the transfer bump 21 is a circular surface, and the diameter d2 of the transfer end face 211 is in the range of 20μm-1mm. In this way, when using the lithium battery separator dispensing and coating device of the present invention to coat a non-fully covered coating layer on the coating film, the transfer end face 211 of the transfer bump 21 being too small or too large can be avoided from affecting the transfer of the coating adhesive, thus facilitating the transfer of the coating adhesive on the anilox roller 1. When the transfer bump 21 is a stepped truncated pyramid structure, the transfer bump 21 includes a connecting base 2101 and a transfer boss 2102, and the cross-sectional area of ​​the transfer boss 2102 is smaller than the cross-sectional area of ​​the connecting base 2101. In this way, the cross-sectional area of ​​the transfer protrusion 21 at the transfer end face 211 is relatively small, and the cross-sectional area of ​​the transfer end face 211 is the smallest compared to other parts of the transfer protrusion 21, so as to facilitate the insertion into the material receiving groove 11 when in contact with the anilox roller 1 to transfer the coating material on the anilox roller 1. Preferably, the transfer boss 2102 is a cylindrical structure with a height h1 ≤ 200 μm and a ratio N ≤ 2.5 between the height h1 and the diameter d2. The connecting base 2101 is a truncated cone structure. In this way, the ratio N ≤ 2.5 between the height h1 and the diameter d2 of the cylindrical transfer boss 2102 can avoid the transfer protrusion 21 being too thin and long during the transfer of the coating material, which would affect the transfer effect and thus the subsequent coating effect. In addition, the truncated cone structure of the connecting base 2101 can effectively support the transfer boss 2102 and is also convenient to manufacture. The feed rate controller is used to detect and modulate the distance between the letterpress roller 2 and the anilox roller 1, thereby adjusting the feed rate of the transfer protrusion 21 on the letterpress roller 2 into the material-containing groove 11 on the anilox roller 1. Preferably, the feed rate controller can be a grating ruler. Using a grating ruler as the feed rate controller simplifies installation and operation, provides high detection and control accuracy, and facilitates the coating operator's control over the thickness of the coating layer. Preferably, the ratio Q of the inner diameter d1 of the material-containing groove 11 on the anilox roller 1 to the end face diameter d2 of the transfer end of the transfer protrusion 21 on the letterpress roller 2 is ≥150%.In this way, the end area of ​​the transfer end of the transfer protrusion 21 is much smaller than the cross-sectional area of ​​the material receiving groove 11, so that the transfer end of the transfer protrusion 21 can be inserted into the material receiving groove 11 of the anilox roller 1. The tension of the coating material is used to make the coating material adhere to the transfer end of the transfer protrusion and form a spherical or ellipsoidal coating material droplet 09. The coating material droplet 09 will not squeeze the coating film during the transfer process, but will mainly drip onto the coating film through the tension difference between different materials. The thickness of the coating layer formed by the coating can be adjusted by adjusting the tension of the coating material and the size of the coating material droplet 09, which is simple and convenient.

[0045] In addition, the specific process of forming a coating layer on a coating film using the dispensing method provided in the embodiments of the present invention is as follows:

[0046] First, a coating adhesive is applied to the material-holding groove 11 on the roller surface of the anilox roller 1, forming a uniform liquid film layer within the groove 11. Preferably, excess liquid film on the roller surface of the anilox roller 1 can be squeezed or scraped by a roller or a doctor blade to form a uniform liquid film layer within the mesh. When a roller is used, the roller is close to the roller surface of the anilox roller 1 and contacts the coating adhesive on the roller surface of the anilox roller 1, squeezing and removing excess coating adhesive. During the rotation of the anilox roller 1, a uniform liquid film layer is formed within the mesh of the anilox roller 1. When a doctor blade is used, the doctor blade is close to the roller surface of the anilox roller 1, and during the rotation of the anilox roller 1, the doctor blade scrapes and removes excess coating adhesive from the roller surface of the anilox roller 1, forming a uniform liquid film layer within the mesh of the anilox roller 1. Similarly, the anilox roller can be replaced with a smooth roller or a textured roller with greater surface adhesion. The thickness of the liquid film layer formed by coating can be adjusted by adjusting the distance between the roller or doctor blade and the surface of the smooth roller or textured roller with greater surface adhesion. The operation is simple and convenient.

[0047] Next, according to the coating requirements, the feed amount of the transfer protrusion 21 on the letterpress roller 2 is adjusted by the feed amount controller to insert into the material receiving groove 11 on the anilox roller 1. That is, the value of the distance L between the transfer end face 211 of the transfer protrusion 21 and the bottom of the groove 11 is adjusted. The anilox roller 1 and the letterpress roller 2 are driven to rotate in opposite directions by a drive device such as a drive motor, so that the transfer protrusion 21 on the letterpress roller 2 is inserted into the material receiving groove 11 on the anilox roller 1 in sequence and the coating adhesive in the material receiving groove 11 is carried out, forming a coating adhesive droplet 09 covering the transfer end face 211 of the transfer protrusion 21.

[0048] Finally, the driving device drives the flat bottom roller 3 to rotate in the opposite direction to the letterpress roller 2, which drives the coating film 4 located in the film-passing gap 31 to move along the direction k, so that the coating adhesive droplets 09 on the transfer protrusions 21 on the letterpress roller 2 are dripped onto the coating film 4 and form coating points on the coating film 4 that constitute a non-full coverage coating layer. Figure 8 As shown, when the transfer protrusion 21 on the letterpress roller 2 is a concave cone structure, a semi-ellipsoidal coating point 9 is formed on the coating film 4.

[0049] When using the above-described dispensing and coating apparatus to form a coating layer on a coating film, a coating adhesive with a viscosity ranging from 300 Pa·s to 15000 Pa·s at room temperature is preferred. This allows for the formation of coating adhesive droplets with a height ranging from 1 μm to 50 μm and a diameter ranging from 50 μm to 1000 μm on the transfer bumps during the transfer process, thereby meeting the requirement for forming a coating layer with a relatively large thickness.

[0050] Figure 9 This is a schematic diagram of the coating layer prepared using the dispensing apparatus of this invention, where the transfer protrusion is a conical truncated pyramid structure with a concave busbar. From... Figure 9 It can be seen that the transfer bumps hardly contact the diaphragm (coated film), but mainly use the tension difference to transfer the second coated adhesive droplet 09, forming the first coated adhesive droplet 9 on the diaphragm, and the first coated adhesive droplet 9 formed is in the shape of an approximately spherical or ellipsoidal droplet.

[0051] Table 1 compares the parameters of separators produced using existing processes with those produced using this method. The island-shaped spray-coated film is prepared using fourth-generation rotary spraying, and the roll-coated shrink film is prepared using third-generation full-coat shrink coating. The meanings of each parameter are as follows: 1. Lower areal density indicates less material usage; 2. Higher puncture strength indicates better strength and a safer battery; 3. Higher conductivity indicates faster charging and discharging speeds; 4. Lower sheet resistance indicates smoother lithium-ion penetration; 5. Gas permeability: the time required for a unit volume of gas to pass through the separator area; shorter time indicates smoother permeability.

[0052] Table 2 compares the two dot coating techniques.

[0053] Table 1

[0054] parameter Uniform dot-coated film (in this embodiment) Roller-coated shrink film Island-shaped spray coating film Surface density (g / m2) 15.01 15.85 17.15 Puncture intensity (N) 7.43 6.95 7.2 Ionic conductivity (S / cm) 12.7*10-4 8.7*10-4 9.1*10-4 Surface resistance (Ω) 1.71 2.36 3.23 Breathability (s) 235 333 286

[0055] Table 2

[0056]

Claims

1. A lithium battery separator dispensing and coating device, characterized in that, The coating transfer device includes a material receiving device and a letterpress roller (2). The material receiving device is provided with a material receiving groove (11) for receiving the material. The letterpress roller (2) is provided with a transfer protrusion (21) on its roller surface. The transfer protrusion (21) is adapted to be inserted into the material receiving groove (11) at the corresponding position on the material receiving device to transfer the diaphragm coating. Due to the difference in viscosity and tension, the diaphragm coating forms a coating droplet covering the transfer end face (211) of the transfer protrusion (21). The flat bottom roller (3) rotates in the opposite direction relative to the material receiving device, driving the coating film (4) to move, so that the coating droplets on the transfer protrusion (21) are deposited on the coating film (4) and form a non-fully covered coating layer on the coating film (4). The coating droplets are deposited on the coating film by the tension difference of different materials. It also includes a feed rate controller and a flat bottom roller (3). The flat bottom roller (3) is located below the coating transfer device, and a film-passing gap (31) is provided between the flat bottom roller (3) and the coating transfer device for the coating film (4) to pass through. The feed rate controller is used to detect and adjust the feed rate of the transfer protrusion (21) on the letterpress roller (2) inserted into the material receiving groove (11) in the material receiving device. Adjusting the feed rate of the transfer protrusion on the letterpress roller inserted into the material receiving groove in the material receiving device adjusts the thickness of the prepared coating layer.

2. The lithium battery separator dispensing and coating apparatus according to claim 1, characterized in that, It also includes an applicator that abuts against the adhesive container, so that the coating forms a liquid film layer of uniform thickness on the surface of the adhesive container.

3. The lithium battery separator dispensing and coating apparatus according to claim 2, characterized in that, The coating device includes a roller or a scraper, which respectively squeezes or scrapes the adhesive receiving device.

4. The lithium battery separator dispensing and coating apparatus according to claim 1, characterized in that, The rubber material receiving device includes an anilox roller (1), a texturing roller, or a smooth roller.

5. The lithium battery separator dispensing and coating apparatus according to claim 1, characterized in that, The ratio Q of the inner diameter d1 of the material-containing groove (11) to the diameter d2 of the transfer end face (211) of the transfer protrusion (21) is greater than or equal to 1.

5.

6. The lithium battery separator dispensing and coating apparatus according to claim 5, characterized in that, The transfer end face (211) of the transfer protrusion (21) is a circular surface. The diameter d2 of the transfer end face (211) is in the range of 20μm-1mm. When the transfer protrusion (21) is inserted into the material receiving groove (11), the distance L between the transfer end face (211) and the bottom of the material receiving groove (11) is in the range of 20μm-250μm.

7. The lithium battery separator dispensing and coating apparatus according to claim 6, characterized in that, The transfer protrusion (21) is a concave cone structure, a convex cone structure, a concave cone structure, or a stepped cone structure.

8. The lithium battery separator dispensing and coating apparatus according to claim 7, characterized in that, The stepped platform structure includes a connecting base (2101) and a transfer boss (2102). The cross-sectional area of ​​the transfer boss (2102) is smaller than that of the connecting base (2101). The transfer boss (2102) is a cylindrical structure, and the connecting base (2101) is a conical platform structure. The height h1 of the cylindrical structure is ≤200μm, and the ratio N of the height h1 of the cylindrical structure to the diameter d2 of the transfer end face is ≤2.

5.

9. The lithium battery separator dispensing and coating apparatus according to claim 1, characterized in that, The different materials mentioned are letterpress rollers and coated films.

10. The lithium battery separator dispensing and coating apparatus according to claim 1, characterized in that, The coating adhesive droplets are also deposited onto the coating film by gravity and centrifugal force.

11. The lithium battery separator dispensing and coating apparatus according to any one of claims 1-3, characterized in that, The feed rate controller includes a grating ruler or other high-precision repeatable positioning device.

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