Battery diaphragm coating control method

Abstract

The invention discloses a battery diaphragm coating control method which comprises the following steps: driving an anilox roller and a smooth roller to rotate reversely to uniformly coat slurry on the smooth roller to form a glue film, and adjusting the rotating speed of the anilox roller to change the thickness of the glue film; the plate roller is driven to reversely rotate with the smooth roller and the back roller, the adhesive film on the smooth roller is transferred to the battery diaphragm dragged to move by the back roller through a plurality of transfer convex points of the plate roller, and the adhesive film is extruded by the transfer convex points to form a coating layer with a dot diagram on the battery diaphragm; the thickness parameter of the coating layer is detected, when the thickness parameter is smaller than the preset thickness, the rotating speed of the anilox roller is reduced, and when the thickness parameter is larger than the preset thickness, the rotating speed of the anilox roller is increased; the problem that in the prior art, when transfer convex points on a plate roller and grooves in a concave roller cannot be correspondingly inserted and matched, coating is not uniform or coating point positions are lost due to material taking failure is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery separator coating, and in particular to a battery separator coating control method. Background Art

[0002] In the prior art, the non-full coverage coating technology commonly used in the preparation of lithium battery diaphragms generally includes PVDF (polyvinylidene fluoride, a highly non-reactive thermoplastic fluorinated polymer) agglomerated shrink coating film and PVDF "island" spray film: the former forms the diaphragm surface by utilizing the hydrophobicity of PVDF, and makes PVDF into agglomerates by adjusting the slurry tension. The slurry shrinks rapidly after contacting the membrane surface, preventing it from forming a continuous structure. Since it is adjusted by the slurry, the stability is very poor; the latter throws PVDF toward the diaphragm through high-speed rotation, forming an island structure on the diaphragm surface to rivet the pole pieces, but the shape is irregular; the slurry diameter on the convex point is limited by the diameter of the gravure roller groove, so if the diaphragm dot coating diameter is to be changed, it needs to be achieved by replacing the gravure roller; and the convex points of the relief roller will produce different degrees of wear with production and use, at which time the volume of the coating point picked by the convex point will decrease. If the size of the coating point is to be maintained, the relief roller can only be replaced.

[0003] A common method for forming a non-full coverage coating layer is: first, the recessed holes or grooves on the roller surface of the anilox roller are filled with coating slurry; then, the raised points on the relief roller are extended into the recessed holes or grooves during the contact with the anilox roller to transfer the slurry, and during the transfer process, the platform back roller is used to squeeze the transfer surface of the raised points on the relief roller, and the slurry on the transfer surface of the raised points is transferred from the platform back roller and the relief roller, thereby forming a uniform "dot-shaped" coating layer on the side of the diaphragm facing the relief roller.

[0004] Since the diameter of the convex dots is generally less than 1 mm, the convex dots on the plate roller need to correspond to the concave dots on the concave roller during the relative rotation of the plate roller and the concave roller. When wear or offset occurs, the convex dots cannot be accurately inserted into the concave grooves to take the material, resulting in uneven coating on the diaphragm or loss of coating points. Summary of the invention

[0005] 1. Technical issues

[0006] The purpose of the present invention is to provide a battery diaphragm coating control method to solve the problem in the prior art that when the transfer convex points on the plate roller and the grooves on the concave roller cannot be inserted and matched correspondingly, the material removal fails, resulting in uneven coating or loss of coating points.

[0007] (II) Technical solution

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A battery diaphragm coating control method is provided, which comprises the steps of driving an anilox roller and a smooth roller to rotate in opposite directions to uniformly coat slurry on the smooth roller to form a film, and adjusting the rotation speed of the anilox roller to change the thickness of the film; driving a plate roller, a smooth roller and a back roller to rotate in opposite directions, transferring the film on the smooth roller to a battery diaphragm pulled and moved by the back roller through a plurality of transfer convex points of the plate roller, and squeezing the film to form a coating layer with a dot pattern on the battery diaphragm by the plurality of transfer convex points; and detecting a thickness parameter of the coating layer, and reducing the rotation speed of the anilox roller when the thickness parameter is less than a preset thickness, and increasing the rotation speed of the anilox roller when the thickness parameter is greater than the preset thickness.

[0010] Preferably, the cross-sectional shape of the transfer protrusion is ring-shaped, flower-shaped or polygonal.

[0011] Preferably, the diameter of the transfer bump is in the range of 20 μm-1 mm.

[0012] Preferably, the viscosity value of the slurry is detected, and the smooth roller of different materials is replaced based on the viscosity value; when the slurry is high viscosity, the material of the smooth roller is steel; when the slurry is medium viscosity, the material of the smooth roller is plastic; when the slurry is low viscosity, the material of the smooth roller is frosted material.

[0013] Preferably, it includes a feeding structure for cooperating with the anilox roller to feed the slurry; the feeding structure is a slurry tank, and the anilox roller is placed in the slurry tank; or, the feeding structure is a scraper-type slurry feeding mechanism cooperating with the anilox roller; or, the feeding structure is a comma scraper coating head cooperating with the anilox roller.

[0014] Preferably, the scraper-type slurry feeding mechanism includes a scraper box and a storage cavity provided on the scraper box, and the scraper box is provided with scraper blades located on both sides of the storage cavity and arranged obliquely; one side of the anilox roller is arranged in the storage cavity, and the edge of the scraper blade is slidably matched with the surface of the anilox roller; the scraper box is provided with a feed port located at its bottom and an overflow port located at its top.

[0015] Preferably, the anilox roller, the smooth roller, the plate roller and the back roller are all connected to independent driving motors.

[0016] Preferably, the distribution density of the transfer convex points on the plate roller is 10%-50%.

[0017] Preferably, based on the deviation displacement caused by the pulling movement of the battery separator, the adjustment plate roller moves along the axis in the direction opposite to the deviation displacement.

[0018] Preferably, the array shape of the transfer convex points on the plate roller is rectangular, striped or ring-shaped.

[0019] (III) Beneficial effects

[0020] Different from the prior art method of using transfer convex points to extend into the groove to realize slurry grabbing, the utility model adds a smooth roller between the anilox roller and the plate roller, and realizes the slurry loading and coating on the smooth roller to form a film of corresponding coating thickness through the speed adjustment of the anilox roller, and then transfers the film to the battery separator through the transfer convex points on the plate roller, and the squeezing force between the transfer convex points and the back roller causes the film to be formed on the battery separator by the transfer convex points to form a coating layer with a dot pattern; thus, there is no need to align the transfer convex points when taking the material, thereby improving the efficiency of dot coating success;

[0021] At the same time, the coating thickness is adjusted by adjusting the rotation speed of the anilox roller, which facilitates real-time adjustment based on subsequent coating thickness detection and avoids the complex method of replacing rollers with different groove depths to achieve coating thickness adjustment in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A first coating schematic diagram of the coating control method according to an embodiment of the present invention;

[0023] Figure 2 A second coating schematic diagram of the coating control method according to an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of a slurry feeding method 1 of a coating control method according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a second slurry feeding method using a coating control method according to an embodiment of the present invention;

[0026] Figure 5 for Figure 4 A schematic cross-sectional structure diagram of;

[0027] Figure 6 It is a partial schematic diagram of the first type of plate roller unfolding of the coating control method applied in the embodiment of the present invention;

[0028] Figure 7 A partial schematic diagram of the second roll of the coating control method according to an embodiment of the present invention;

[0029] Figure 8 It is a partial schematic diagram of the third plate roller of the coating control method applied in the embodiment of the present invention;

[0030] exist Figures 1 to 8 In the figure, the corresponding relationship between the component names or lines and the figure numbers is as follows:

[0031] Anilox roller 1, smooth roller 2, plate roller 3, back roller 4, transfer convex point 5, slurry tank 6, scraper-type feeding mechanism 7, scraper box 71, storage chamber 72, scraper blade 73, comma scraper coating head 8, machine base 81, slide rail 82, mounting seat 83, comma scraper roller 84, scraper part 85, connecting beam 86, fixed seat 87, screw 88, push rod 89, push block 810, handle 811, inclined block seat 812, pressure block 813, drive motor 814, battery separator 100. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] See also Figure 1-Figure 2 As shown, a battery diaphragm coating control method is proposed in an embodiment of the present invention. The coating control method proposed in this embodiment aims to solve the problem in the prior art that slurry is loaded by opening grooves on the anilox roller 1, and then the corresponding transfer convex points 5 on the plate roller 3 are inserted into the grooves to realize slurry transfer to realize point coating. The transfer convex points 5 need to be inserted into the grooves accordingly to realize material removal, and the diameter of the transfer convex points 5 is basically less than 1 mm, which is difficult to realize in practice.

[0034] In order to improve this coating method, a new method is proposed.

[0035] After the slurry is stirred in advance and loaded onto the loading structure, the slurry is transferred through the cooperation of the anilox roller 1 and the loading structure, and then the anilox roller 1 and the optical roller 2 are driven to rotate in opposite directions to evenly coat the slurry on the optical roller 2 to form a film. The thickness of the film is changed by adjusting the rotation speed of the anilox roller 1. After the anilox roller 1 and the optical roller 2 rotate relative to each other, the slurry forms a film on the optical roller 2. The thickness of the film is related to the rotation speed of the anilox roller 1. The faster the speed, the thinner the thickness, and the slower the speed, the thicker the thickness.

[0036] At the same time, the plate roller 3 is driven to rotate in the opposite direction to the smooth roller 2 and the back roller 4, and the adhesive film on the smooth roller 2 is transferred to the battery separator 100 pulled by the back roller 4 through the several transfer convex points 5 of the plate roller 3. The several transfer convex points 5 squeeze the adhesive film to form a coating layer with a dot pattern on the battery separator 100. When the adhesive film is transferred to the battery separator 100 through the several transfer convex points 5 on the plate roller 3, no alignment is required. The adhesive film is separated from the smooth roller 2 and pulled onto the battery separator 100 by utilizing the fit between the transfer convex points 5 and the smooth roller 2, and the adhesive film is pressed onto the battery separator 100 under the cooperation of the plate roller 3 and the back roller 4, and the transfer convex points 5 cooperate with the smooth roller 2 to form a dot-shaped distribution pattern on the adhesive film, thereby completing the coating of the dot pattern coating layer on the battery separator 100.

[0037] Specifically, when realizing the coating layer, the distance between the plate roller 3 and the optical roller 2 can be adjusted and fixed in advance, and the distance can be controlled to achieve that the raised height of the transfer bump 5 is the same as the thickness of the film on the optical roller 2, thereby ensuring the material intake of the transfer bump 5. At the same time, there is residual material on the plate roller 3 to ensure that a reliable coating layer is formed on the battery separator 100 during the coating process.

[0038] Specifically, during the entire coating process, the thickness parameter of the coating layer is detected. When the thickness parameter is less than the preset thickness, the rotation speed of the anilox roller 1 is reduced. When the thickness parameter is greater than the preset thickness, the rotation speed of the anilox roller 1 is increased. By detecting the thickness of the coating layer, the speed of the anilox roller 1 is controlled and adjusted to ensure that the loading amount from loading to coating meets the final coating thickness requirement.

[0039] Among them, when performing thickness detection, film thickness detection is achieved through a displacement sensor. For example, a thickness detection is performed before coating the battery separator 100 to obtain a first thickness value, and then a thickness detection is performed after coating to obtain a second thickness value. The absolute value of the difference between the first thickness value and the second thickness value is compared with a predetermined deviation value. If the error range is within the rotation speed, the rotation speed is kept unchanged. If the rotation speed exceeds the upper limit of the error range, the rotation speed is increased, and if the rotation speed is lower than the error range, the rotation speed is increased. The error range can be ±5%.

[0040] Specifically, the transfer bumps 5 on the plate roller 3 can be machined or engraved on the plate roller 3 using a laser engraving process. The diameter range of the transfer bumps 5 is 20μm-1mm, and the distribution density of the transfer bumps 5 on the plate roller 3 is 10%-50%. The coverage of the transfer bumps 5 is increased as much as possible, and the dot distribution on the coating layer is as uniform as possible.

[0041] Among them, Figure 6-Figure 8 As shown, the cross-sectional shape of the transfer protrusion 5 is ring-shaped, flower-shaped, or polygonal, or can be formed into other shapes according to the coating pattern requirements. At the same time, the array shape of the transfer protrusion 5 on the plate roller 3 is rectangular, striped, or ring-shaped. The array shape can also be other shapes, mainly to ensure that the transfer protrusions 5 are evenly spaced.

[0042] Specifically, in the process of transferring the slurry from the loading position to the smooth roller 2 through the anilox roller 1, it is necessary to ensure that a film of uniform thickness is formed on the smooth roller 2. Therefore, it is necessary to change the material of the smooth roller 2 according to the viscosity value of the slurry. The following method is used to detect the viscosity value of the slurry and replace the smooth roller 2 of different materials based on the viscosity value. The viscosity value is obtained by testing the slurry before stirring, and the general viscosity value range is 300Pa.s-15000Pa.s. Specifically, when the slurry is of high viscosity, the material of the smooth roller 2 is steel, and the steel with higher finish can ensure the film Separation, generally speaking, high viscosity means a viscosity value greater than 8000Pa.s; when the slurry is of medium viscosity, the material of the smooth roller 2 is plastic, and the plastic material can provide a certain friction force to facilitate the slurry to form a film, and can facilitate the separation of the film. Generally speaking, the viscosity value of medium viscosity is between 4000 and 8000Pa.s; when the slurry is of low viscosity, the material of the smooth roller 2 is frosted material, and the frosted material is mainly on the surface of the smooth roller 2 to increase the friction force, and the low viscosity slurry is formed into a film to ensure the reliability of feeding. The low viscosity means a viscosity value lower than 4000Pa.s. Therefore, the smooth roller 2 is replaced based on the change in the viscosity of the slurry to ensure the stability of the film forming.

[0043] Specifically, it also includes a feeding structure for cooperating with the anilox roller 1 to feed the slurry, such as Figure 2 As shown, the feeding structure is a slurry tank 6, and the anilox roller 1 is placed in the slurry tank 6. The slurry is driven and transferred to the smooth roller 2 directly by the rotation of the anilox roller 1 in the slurry tank 6; in another way, as Figure 3 As shown, the feeding structure can adopt a scraper-type slurry feeding mechanism matched with the anilox roller 1 , and the slurry is coated on the anilox roller 1 through the scraper-type slurry feeding mechanism, and the surface coating thickness is controlled by the rotation speed of the anilox roller 1 .

[0044] Among them, Figure 3 As shown, the scraper-type slurry feeding mechanism includes a scraper box 71 and a storage cavity 72 arranged on the scraper box 71, and the scraper box 71 is provided with scraper blades 73 located on both sides of the storage cavity 72 and arranged obliquely, and one side of the anilox roller 1 is arranged in the storage cavity 72, and the edge of the scraper blade 73 is slidably matched with the surface of the anilox roller 1, and the scraper box 71 is provided with a feed port located at its bottom and an overflow port located at its top; the slurry is circulated into the storage cavity 72 through the feed port and overflows through the overflow port to ensure that the slurry in the storage cavity 72 is full, and the slurry is coated during the rotation of the anilox roller 1, and the coating thickness on the anilox roller 1 is controlled by the scraper.

[0045] At the same time, the feeding method can also apply a third method, such as Figure 4-Figure 5As shown, the feeding structure is a comma scraper coating head 8 that cooperates with the anilox roller 1, wherein the comma scraper coating head 8 includes a machine base 81 and a mounting seat 83 that is obliquely slidably mounted on the machine base 81 through a slide rail 82, and comma scraper rollers 84 are mounted on the two mounting seats 83, and the comma scraper rollers 84 are provided with a scraper portion 85 that is 180° rotationally symmetrical, and the scraper portion 85 cooperates with the anilox roller 1 to achieve uniform slurry feeding on the anilox roller 1. At the same time, a connecting beam 86 is installed on the two mounting seats 83, and a fixed seat 87 and a screw 88 that is rotatably mounted on the fixed seat 87 are provided on the connecting beam 86, and a top rod 89 is also slidably provided on the fixed seat 87, and the top rod 89 is threadedly matched with the screw 88, and a top block 810 is provided on the top rod 89, and the top block 810 is fixedly connected to the comma scraper roller 84.

[0046] A handle 811 is mounted on the screw rod 88 .

[0047] An inclined block seat 812 is installed on the connecting beam 86 , and a pressing block 813 that fits with the comma scraper roller 84 is installed at the end of the inclined block seat 812 .

[0048] The base 81 is provided with a driving motor 814 for adjusting the sliding displacement of the mounting base 83 .

[0049] Specifically, when the slurry is fed, one of the three implementation modes mentioned above may be adopted.

[0050] Specifically, the anilox roller 1, the smooth roller 2, the plate roller 3 and the back roller 4 are all connected to independent driving motors, and the corresponding rotation speeds and directions are independently controlled to ensure stable transfer of the slurry from feeding to coating.

[0051] At the same time, the battery separator 100 may be offset during the traction process. It is necessary to adjust the plate roller 3 in the opposite direction of the deviation displacement and move along the axis based on the deviation displacement of the current battery separator 100, so as to ensure that the coating position of the coating layer on the battery separator 100 meets the coating requirements.

[0052] The method of adjusting the coating position based on the deviation displacement is realized on the basis of the coating method proposed in this embodiment. There is no need to adjust the transfer bumps 5, and the position of the plate roller 3 can be directly adjusted to match the current position of the battery separator 100.

[0053] At the same time, after the deviation of the battery separator 100 is corrected, the plate roller 3 is also adjusted in real time following the position of the battery separator 100 .

[0054] Among them, an infrared sensor or a displacement sensor can be used to detect the deviation displacement of the battery diaphragm 100, and the corresponding signal is obtained through real-time detection to control whether the plate roller 3 needs to be adjusted through the controller. The specific adjustment mechanism used for adjusting the plate roller 3 along the axial direction can be a screw mechanism or a gear rack mechanism and other existing technologies.

[0055] It should be noted that this embodiment is mainly to realize the slurry loading, transfer and coating without adopting the one-to-one correspondence between the transfer bumps 5 and the grooves, and other structures and principles related to the coating machine implementation mechanism can adopt the existing technology.

[0056] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A battery separator coating control method, characterized in that: The anilox roller and the smooth roller are driven to rotate in opposite directions to evenly coat the slurry on the smooth roller to form a film, and the thickness of the film is changed by adjusting the rotation speed of the anilox roller; The plate roller is driven to rotate in the opposite direction to the smooth roller and the back roller, and the rubber film on the smooth roller is transferred to the battery separator pulled by the back roller through a number of transfer convex points of the plate roller. The several transfer convex points squeeze the rubber film to form a coating layer with a dot pattern on the battery separator; The thickness parameter of the coating layer is detected. When the thickness parameter is less than the preset thickness, the rotation speed of the anilox roller is reduced. When the thickness parameter is greater than the preset thickness, the rotation speed of the anilox roller is increased.

2. A battery separator coating control method according to claim 1, characterized in that: The cross-sectional shape of the transfer protrusion is ring-shaped, flower-shaped or polygonal.

3. A battery separator coating control method according to claim 2, characterized in that: The diameter of the transfer bumps ranges from 20 μm to 1 mm.

4. A battery separator coating control method according to claim 1, characterized in that: Detect the viscosity of the slurry and replace the smooth rollers of different materials based on the viscosity value; When the slurry is of high viscosity, the smooth roller is made of steel; When the slurry is of medium viscosity, the material of the smooth roller is plastic; When the slurry is of low viscosity, the material of the smooth roller is a frosted material.

5. A battery separator coating control method according to claim 1, characterized in that: It includes a feeding structure for cooperating with anilox roller to feed slurry; The feeding structure is a slurry tank, and the anilox roller is placed in the slurry tank; Or, the feeding structure is a scraper-type slurry feeding mechanism matched with an anilox roller; Alternatively, the feeding structure is a comma blade coating head matched with an anilox roller.

6. A battery separator coating control method according to claim 5, characterized in that: The scraper-type slurry feeding mechanism comprises a scraper box and a material storage cavity provided on the scraper box, and the scraper box is provided with scraper blades which are located on both sides of the material storage cavity and are arranged obliquely; One side of the anilox roller is arranged in the material storage cavity, and the edge of the scraper blade is slidably matched with the surface of the anilox roller; The scraper box is provided with a feed port at the bottom and an overflow port at the top.

7. A battery separator coating control method according to any one of claims 1 to 6, characterized in that: The anilox roller, the smooth roller, the plate roller and the back roller are all connected with independent driving motors.

8. A battery separator coating control method according to claim 7, characterized in that: The distribution density of the transfer convex points on the plate roller is 10%-50%.

9. A battery separator coating control method according to claim 8, characterized in that: Based on the deviation displacement caused by the pulling movement of the battery diaphragm, the adjustment plate roller moves along the axis in the direction opposite to the deviation displacement.

10. A battery separator coating control method according to claim 9, characterized in that: The array shape of the transfer convex points on the plate roller is rectangular, striped or ring-shaped.

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