Winding coating equipment and winding coating method

Abstract

The invention discloses winding coating equipment and a winding coating method. The winding coating equipment comprises a vacuum chamber and a computing control center, and an even number of coating rollers are arranged in the vacuum chamber. And conductive coatings are deposited on the two surfaces of the flexible thin film through vacuum evaporation coating when the flexible thin film winds around each coating roller. Negative bias voltage is applied to the two surfaces, where the conductive coatings are deposited, of the flexible film, and positive bias voltage is applied to each coating roller. Except the first coating roller, the two sides of each coating roller are each provided with a voltage measuring roller, and the voltage measuring rollers are used for measuring the voltage of the surface, making contact with the voltage measuring rollers, of the flexible film on line. The calculation control center obtains bias voltage values of all the coating rollers, voltage measurement values of all the voltage measurement rollers and the temperature and flow of the cooling medium in all the coating rollers in real time, and then the bias voltage values of all the coating rollers except the first coating roller are regulated and controlled in real time through comprehensive calculation and analysis. Therefore, the attaching force and the initial surface temperature of the flexible film on each coating roller are regulated and controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum roll-to-roll coating, and in particular relates to a roll coating device and a roll coating method for preparing a conductive coating on a flexible film. Background Art

[0002] Recently, the industry has proposed using vacuum roll-to-roll evaporation coating technology to deposit conductive film layers such as copper or aluminum metal on the front and back sides of flexible films of polymer materials to form a new "sandwich" current collector for lithium battery products. During the evaporation process, in order to avoid thermal deformation and thermal damage of the flexible film, cooling water is generally passed through the coating roller to cool the flexible film passing through it. In this case, the adhesion between the flexible film and the coating roller will directly affect the cooling effect.

[0003] At present, the industry generally adjusts the adhesion between the flexible film and the coating roller by adjusting the tension roller. However, this method has poor control accuracy and it is difficult to make the flexible film adhere evenly to all parts in contact with the coating roller, making it difficult to achieve an ideal cooling effect. The pulling effect on the flexible film during the adjustment process can easily cause harmful stress in the film layer during the deposition process, which has a certain impact on the quality of the film layer.

[0004] In order to improve this problem, an electrostatic bias adsorption method is also proposed. By applying a certain voltage with opposite polarity on the coating roller and the flexible film, the flexible film is adsorbed on the coating roller to improve the cooling effect. The electrostatic adsorption force is mainly related to the distance between the voltage application surface on the flexible film and the voltage application surface on the coating roller, as well as the voltage difference between the two. This electrostatic bias adsorption method is effective for preparing a film layer on a single side of the flexible film by winding the flexible film around only one coating roller. However, in the process of preparing a new current collector, when the flexible film needs to be wound around multiple coating rollers to deposit a conductive film layer on both sides of the flexible film, there is often a situation where the film thickness and conductivity and other properties deposited on the front and back sides of the flexible film are inconsistent, making the product quality and performance unstable, causing troubles for manufacturers. Summary of the invention

[0005] To solve the above problems, the present invention provides a winding coating device and a winding coating method for preparing a conductive coating on the front and back sides of a flexible film, which can be applied to the mass production of a new composite current collector to prepare a conductive layer on the front and back sides of a flexible film by vacuum coating. The roll coating equipment comprises a vacuum system, a vacuum chamber and a computing control center; the vacuum system is used for evacuating the vacuum chamber; an unwinding roller, a winding roller and n coating rollers are arranged in the vacuum chamber, wherein n is an even number ranging from 4 to 10; the flexible film is unwound from the unwinding roller, and a conductive coating is deposited on the surface of the flexible film by vacuum evaporation coating when it is wound around coating roller No. 1 to coating roller No. n in sequence, and then it is wound up by the winding roller; a cooling medium is passed through the interior of the coating roller, the surface of the coating roller is made of stainless steel, and an electrical insulating layer is arranged on the outer layer of the surface; when the flexible film is wound around two adjacent coating rollers, a conductive coating is deposited on two different surfaces of the flexible film respectively; a first bias roller is arranged downstream of coating roller No. 1, and is used to apply a negative bias to the first surface of the flexible film on which the conductive coating has been deposited; a second bias roller is arranged downstream of coating roller No. 2, and is used to apply a negative bias to the second surface of the flexible film on which the conductive coating has been deposited pressure; except for coating roller No. 1, a voltage measuring roller is arranged on both sides of each coating roller, and they are numbered sequentially from voltage measuring roller No. 1 upstream of coating roller No. 2 to voltage measuring roller No. n downstream of coating roller No. n; the voltage measuring roller is used to measure the voltage of the surface of the flexible film in contact with the voltage measuring roller online; the computing control center applies a positive bias with an initial bias value on the surface of each coating roller in advance through a bias generating device; the computing control center obtains in real time the bias value on each coating roller, the bias value applied by the first bias roller and the second bias roller, the voltage measurement value from each voltage measuring roller, and the temperature and flow rate of the cooling medium in each coating roller, and then adjusts in real time the bias value to be applied to coating rollers No. 2 to No. n through comprehensive calculation and analysis, so as to adjust the adhesion force of the flexible film on coating rollers No. 2 to No. n, so that the initial surface temperature of the coating surface of the flexible film tends to be consistent when the flexible film passes through each coating roller.

[0006] The cooling medium inside the coating roller is one selected from pure water, glycerin-type coolant, and alcohol coolant.

[0007] The electrical insulation layer has good thermal conductivity and a thickness of 5 to 200 μm. Preferably, the electrical insulation layer is made of ceramic.

[0008] At least one evaporation source is arranged under each coating roller.

[0009] Preferably, the first bias roller and the second bias roller are made of stainless steel, and the surface of the voltage measuring roller is made of copper.

[0010] The bias value accuracy of the positive bias voltage applied to the coating roller and the negative bias voltage applied to the first bias roller and the second bias roller is 0.001V, and the measurement accuracy of the voltage measuring roller is 0.001V. The positive bias voltage applied to the coating roller ranges from 0 to 600V. The negative bias voltage applied to the first bias roller and the second bias roller ranges from -100 to 0V.

[0011] The material of the conductive coating is one selected from copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron and stainless steel.

[0012] The present invention also provides a winding coating method based on the above-mentioned winding coating equipment. In the winding coating method, when the flexible film is wound around two adjacent coating rollers, a conductive coating is deposited on two different surfaces of the flexible film respectively; the flexible film path length between each roller and the material properties of the conductive coating are preset in the computing control center.

[0013] The comprehensive analysis and calculation process of the computing control center includes:

[0014] (1) Film thickness calculation: For the No. 1 voltage measuring roller and the No. 2 voltage measuring roller on both sides of the No. 2 coating roller, the difference between the bias value applied by the first bias roller or the second bias roller and the voltage measurement value of the voltage measuring roller adjacent to the bias roller, as well as the flexible film path length between the bias roller and the corresponding voltage measuring roller, are used to calculate and analyze the conductive coating film thickness t1 of the surface of the flexible film in contact with the No. 1 voltage measuring roller and the conductive coating film thickness t2 of the surface of the flexible film in contact with the No. 2 voltage measuring roller. For the remaining voltage measuring rollers, the difference between the voltage measurement value of the No. m voltage measuring roller and the voltage measurement value of the (m-2) voltage measuring roller located on the same side of the flexible film as the No. m voltage measuring roller, as well as the flexible film path length between the two voltage measuring rollers, are used to calculate and analyze the conductive coating film thickness t m ;

[0015] (2) Calculation of the bias voltage value of the coating roller: For coating roller No. x, based on the voltage measurement values ​​of the voltage measuring roller No. (x-1) and the voltage measuring roller No. x, the initial bias voltage value on the coating roller No. x, and the thickness of the conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the temperature and flow rate of the cooling medium in the coating roller No. x, and calculate the bias voltage value that needs to be applied to the coating roller No. x after regulation;

[0016] Among them, 2≤x≤n, 3≤m≤n; when x=2, t (x-2) is t0, and t0 indicates that there is no conductive coating on the surface of the flexible film at this location.

[0017] In the calculation of the bias value of the coating roller, it also includes establishing a cooling model for the flexible film when it passes around coating roller No. 1. Using this cooling model, the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No. 1 are accurately obtained through analytical simulation. The initial surface temperature T1 of the flexible film when it passes around coating roller No. 1 is related to the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No. 1. The accuracy of T1 is ±0.1°C.

[0018] The calculation of the bias value of the coating roller also includes establishing a cooling model for the flexible film when it is wound around the coating roller No. x; using this cooling model, the voltage measurement values ​​of the voltage measuring roller No. (x-1) and the voltage measuring roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the thickness of the base film of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the adhesion force F between the flexible film and the surface of the coating roller No. x related to the initial bias value on the coating roller No. x x .

[0019] The calculation of the bias value of the coating roller also includes the adhesion force F obtained by analytical simulation. x , as well as the temperature and flow rate of the cooling medium in the coating roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the initial surface temperature T of the flexible film when it is wound around the coating roller No. x. x , and then make the initial surface temperature T x The initial surface temperature T1 of the flexible film when it is wound around the coating roller No. 1 is taken as the control target, and the bias value that needs to be applied to the coating roller No. x after adjustment is accurately obtained through iterative calculation. x The judgment condition for consistency with T1 is that the difference between the two is no more than ±0.05℃.

[0020] The physical structure of the cooling model of the flexible film when it is wound around the coating roller No. 1 is: cooling medium-coating roller surface-electrical insulation layer-flexible film base film-conductive coating layer. The physical structure of the cooling model of the flexible film when it is wound around the coating roller No. x is: cooling medium-coating roller surface-electrical insulation layer-conductive coating layer-flexible film base film-conductive coating layer.

[0021] When the flexible film is passed through coating rollers No. 1 to No. n in sequence, a layer of conductive coating material is deposited on one surface of the flexible film by vacuum evaporation coating each time it passes through a coating roller, so that the thickness of the conductive coating on the surface increases. When the flexible film completes the deposition of the last layer of conductive coating material on coating roller No. n, each surface of the flexible film has undergone n / 2 depositions of conductive coating material. At this time, the thickness of the conductive coating on the two surfaces is t n and t (n-1) , t n and t (n-1) All are in the range of 0.3 to 1.5 μm.

[0022] In the preparation process of the new composite current collector, it is necessary to prepare a thicker conductive coating on the front and back sides of the flexible film by vacuum evaporation coating. The inventors have found in practice that the composite current collector products prepared by the existing vacuum evaporation coating control method often have problems with the consistency and stability of the film quality and electrical properties of the conductive coating on both sides of the flexible film, which affects the stable use of the composite current collector products. The inventors conducted microscopic inspections and simulation analysis on the composite current collector and its conductive coating and found that the above problems are mainly caused by certain differences in the film thickness and structural properties of the conductive coating deposited on the front and back sides. In the prior art, when the electrostatic bias adsorption method is used to enhance the cooling effect of the flexible film on the coating roller, it is mostly implemented by applying a bias voltage of a certain bias value and opposite polarity to the conductive coating layer of the flexible film and the coating roller. In this way, when vacuum coating the first film layer of the flexible film, the physical structure of the heat exchange between the flexible film and the coating roller is cooling medium—coating roller surface—flexible film base film—conductive coating layer with bias. When vacuum coating the second film layer of the flexible film, the physical structure of the heat exchange between the flexible film and the coating roller becomes cooling medium—coating roller surface—conductive coating layer with bias—flexible film base film—conductive coating layer with bias. The difference in physical structure between the two makes the distance between the bias action surface of the flexible film and the coating roller change to different degrees when the second film layer of the flexible film is vacuum coated, because there is a certain thickness of the conductive coating layer and the flexible film base film in the physical structure. The thickness of the conductive coating layer changes, so that when the second film layer of the flexible film is vacuum coated, the adhesion between the flexible film and the coating roller is higher or lower than that when the first film is coated, and then the cooling effect of the flexible film on the coating roller is higher or lower when the two sides are coated. On the other hand, in addition to affecting the electrostatic adsorption effect, more importantly, this difference in physical structure will directly cause the corresponding difference in the heat exchange interval medium between the outer surface to be deposited and the coating roller, which will also cause a difference in the cooling effect of the flexible film on the coating roller when the two sides are coated. The overall effect of these two factors combined will cause the initial temperature of the coating surface of the flexible film to be higher or lower when the two sides are coated, and this difference is often ignored. The inventors discovered that when coating the front and back sides of a flexible film, the difference in initial temperature of the coating surface will affect the film-forming behavior of the deposited material when generating the film layer, resulting in a certain degree of difference in the microstructural properties and film thickness of the second film layer from the first film layer. When the flexible film is deposited on the front and back sides multiple times on multiple coating rollers, this difference effect will become more serious and more obvious, ultimately resulting in serious problems in the composite current collector such as poor consistency and stability of the film quality and electrical properties of the conductive coating on both sides of the flexible film, affecting the stable use of the composite current collector product.

[0023] The winding coating method of the present invention adopts the winding coating equipment of the present invention. When the flexible film is wound around n coating rollers, a layer of conductive coating material is deposited on one surface of the flexible film by vacuum evaporation coating each time it is wound around one coating roller, and when it is wound around two adjacent coating rollers, the conductive coating is deposited on two different surfaces of the flexible film respectively. Negative bias is applied to both surfaces of the flexible film on which the conductive coating has been deposited, and the calculation control center pre-applies a positive bias with an initial bias value to the surface of each coating roller through a bias generating device. An electrical insulating layer is provided on the outer layer of the coating roller surface to prevent the conductive coating with the bias from being electrically neutralized when it contacts the coating roller. The voltage measuring rollers on both sides of the coating roller are used to measure the voltage of the surface of the flexible film in contact with the voltage measuring roller online. The calculation control center is pre-set with fixed parameters such as the flexible film path length between the rollers, the material properties of the conductive coating, the base film thickness of the flexible film, and the thickness of the electrical insulation layer of each coating roller. During the vacuum evaporation coating process, the calculation control center also obtains in real time the bias value on each coating roller, the original bias value applied on the conductive coating, the voltage measurement value from each voltage measuring roller, and the temperature and flow rate of the cooling medium in each coating roller. Then, through comprehensive calculation and analysis, the bias value to be applied to the coating rollers 2 to n is adjusted in real time, thereby adjusting the adhesion force of the flexible film on the coating rollers 2 to n, so that the initial surface temperature of the coating surface of the flexible film tends to be consistent when it passes through each coating roller. Specifically, firstly, based on the fixed parameters such as the flexible film path length between the rollers and the material properties of the conductive coating, as well as the process variable parameters such as the voltage measurement value of each voltage measuring roller, the thickness of the conductive coating layer of each section of the flexible film is calculated and analyzed. Then, a cooling model of the flexible film when it passes through the coating roller is established. The establishment of the cooling model fully considers the relative position relationship between the conductive coating and the flexible film base film in the physical structure and the changes in the thickness of the conductive coating at different coating stages. Then, the cooling model is used to combine the fixed parameters such as the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of each coating roller, as well as the process-varying parameters such as the voltage measurement value of each voltage measuring roller, the initial bias value on each coating roller, and the thickness of the conductive coating layer of each section of the flexible film to analyze and simulate the adhesion between the flexible film and the surface of each coating roller. Finally, the adhesion obtained by simulation is analyzed using the fixed parameters such as the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of each coating roller, as well as the process-varying parameters such as the temperature and flow rate of the cooling medium in each coating roller and the thickness of the conductive coating layer of each section of the flexible film to analyze and simulate the initial surface temperature T of the flexible film when it passes through each coating roller. x , and then make the initial surface temperature T x The control target is the initial surface temperature T1 of the flexible film when it is wound around the No. 1 coating roller, and the bias value that needs to be applied to each coating roller after regulation is accurately obtained through iterative calculation.x The judgment condition consistent with T1 is that the difference between the two is no more than ±0.05°C. The voltage measuring roller accurately measures the voltage of each section of the flexible film and accurately controls the bias voltage on each coating roller in real time, thereby controlling the adhesion force of the flexible film on each coating roller, and then accurately controlling the initial surface temperature of the coating surface of the flexible film when it passes through each coating roller. The ultimate goal is to make the initial surface temperature of the coating surface of the flexible film tend to be consistent when it passes through each coating roller. When the fixed parameters of coating roller No. 1, such as the temperature and flow rate of the cooling medium, the bias value, or other process variable parameters, fluctuate, the computing control center in the winding coating equipment and method of the present invention can still adjust the positive bias voltage on each coating roller in time through real-time control, so that the initial surface temperature of the coating surface of the flexible film when it passes through each coating roller tends to be consistent. This consistency of initial surface temperature remains highly stable throughout the entire winding coating production process. The winding coating method of the present invention realizes that the initial surface temperature of the coating surface of the flexible film is highly consistent when the flexible film is wound around each coating roller. When vacuum evaporation coating is performed on multiple coating rollers, the film-forming behavior of the material depositing on the surface of the flexible film on each coating roller and generating a film layer is also highly consistent, so that the microstructure and film thickness of the conductive coating generated by the multiple deposition processes on the front and back sides are also highly consistent and stable, and finally the film quality and electrical properties of the conductive coating on both sides of the flexible film show high consistency and stability, so that the composite current collector shows stable product performance and service life during long-term use, and overcomes the serious problems of poor consistency and stability of the film quality and electrical properties of the conductive coating on both sides of the flexible film in the industry, so that high-quality composite current collector products can be mass-produced. This technical effect is unattainable by technical means such as the prior art that uses a fixed bias value or adhesion force, or a control method that simply uses a certain bias value or a certain adhesion force as the control target. That is to say, even if the existing technology achieves consistent adhesion between the flexible film and the coating roller when vacuum coating is performed on the front and back sides of the flexible film through certain adjustments, it still cannot solve the problem of the difference in film forming behavior of the deposited film layers between the two, that is, it cannot solve the problem of differences in film quality and electrical properties of the conductive coatings on the front and back sides.

[0024] In addition, the prior art that adopts the technical solution other than the present invention cannot ensure that the initial surface temperature of the coating surface is highly consistent during the film deposition process, resulting in differences in the film formation behavior of the deposited film at the beginning and end of the film formation of the entire film, so that the deposited film will have a large difference in the microstructure of the film in the overall structural direction from bottom to top. This difference makes the electrical properties or other film properties of the film non-linearly related to the physical film thickness, which also brings great trouble to the functional film product designer. The winding coating method of the present invention overcomes this technical problem, not only can the film microstructure and film thickness of the conductive coating on the back of the flexible film be highly consistent with the front conductive coating, but also for the conductive coating on the front or back itself, its film is also uniform in the overall structural direction from bottom to top in terms of the film microstructure. This feature makes the electrical properties or other film properties of the conductive coating on the front or back of the flexible film linearly related to the physical film thickness, which brings great convenience to the product design of composite current collector products or functional film products that use the electrical properties or other film properties of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of an embodiment of the winding coating equipment in the present invention.

[0026] Figure 2 Schematic diagram of the calculation principle of the bias voltage value of the coating roller in the present invention.

[0027] Figure 3 It is a schematic diagram of the physical structure of the cooling model of the flexible film of the present invention when it is wrapped around the No. 1 coating roller.

[0028] Figure 4 It is a physical structure schematic diagram of the cooling model of the flexible film in the present invention when it passes through coating rollers No. 2 to No. n. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] The terms “first”, “second”, “front”, “back”, etc. in the description and claims of the present invention are used to distinguish similar objects but not necessarily to describe a specific order.

[0031] Figure 1 FIG. 1 is a schematic diagram of a structure of an embodiment of the roll-to-roll coating device of the present invention. Figure 1As shown, the roll coating equipment comprises a vacuum chamber 1, a vacuum system 2 and a computing control center 3; the vacuum system 2 is used to evacuate the vacuum chamber 1; a reel 4, a reel 5 and n coating rollers are arranged in the vacuum chamber 1, wherein n is an even number in the range of 4 to 10. Figure 1 In the illustrated embodiment, four coating rollers are arranged in the vacuum chamber 1, namely, coating roller No. 1 6, coating roller No. 2 7, coating roller No. 3 8 and coating roller No. 4 9. The flexible film 10 is unwound from the unwinding roller 4, and a conductive coating layer is deposited on the surface of the flexible film by vacuum evaporation coating when it passes through coating roller No. 1 6 to coating roller No. 4 9 in sequence, and then is taken up by the winding roller 5. A cooling medium is passed through the inside of the coating roller, and the surface of the coating roller is made of stainless steel, and an electrical insulating layer is arranged on the outer layer of the surface. When the flexible film is wound around two adjacent coating rollers, a conductive coating is deposited on two different surfaces of the flexible film respectively; a first bias roller 11 is arranged downstream of the No. 1 coating roller 6, which is used to apply a negative bias to the first surface of the flexible film on which the conductive coating has been deposited; a second bias roller 12 is arranged downstream of the No. 2 coating roller 7, which is used to apply a negative bias to the second surface of the flexible film on which the conductive coating has been deposited; except for the No. 1 coating roller 6, a voltage measuring roller is arranged on both sides of each coating roller, namely, the No. 1 voltage measuring roller 13, the No. 2 voltage measuring roller 14, the No. 3 voltage measuring roller 15 and the No. 4 voltage measuring roller 16. The voltage measuring roller is used to measure the voltage of the surface of the flexible film in contact with the voltage measuring roller online. The computing control center 3 applies a positive bias with an initial bias value on the surface of each coating roller in advance through a bias generating device. The computing control center obtains in real time the bias values ​​on each coating roller, the bias values ​​applied by the first bias roller and the second bias roller, the voltage measurement values ​​from each voltage measuring roller, and the temperature and flow rate of the cooling medium in each coating roller, and then adjusts in real time the bias values ​​to be applied to coating rollers No. 2 to 4 through comprehensive computing and analysis, thereby adjusting the adhesion force of the flexible film on coating rollers No. 2 to 4, so that the initial surface temperature of the coating surface of the flexible film tends to be consistent when it passes through each coating roller.

[0032] The cooling medium inside the coating roller is one selected from pure water, glycerin-type coolant, and alcohol coolant.

[0033] The electrical insulation layer has good thermal conductivity and a thickness of 5 to 200 μm. Preferably, the electrical insulation layer is made of ceramic.

[0034] At least one evaporation source 17 is arranged under each coating roller.

[0035] Preferably, the first bias roller and the second bias roller are made of stainless steel, and the surface of the voltage measuring roller is made of copper.

[0036] The bias value accuracy of the positive bias voltage applied to the coating roller and the negative bias voltage applied to the first bias roller and the second bias roller is 0.001V, and the measurement accuracy of the voltage measuring roller is 0.001V. The positive bias voltage applied to the coating roller ranges from 0 to 600V. The negative bias voltage applied to the first bias roller and the second bias roller ranges from -100 to 0V.

[0037] The material of the conductive coating is one selected from copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron and stainless steel.

[0038] The present invention also provides a winding coating method based on the above-mentioned winding coating equipment. In the winding coating method, when the flexible film is wound around two adjacent coating rollers, a conductive coating is deposited on two different surfaces of the flexible film respectively; the flexible film path length between each roller and the material properties of the conductive coating are preset in the computing control center.

[0039] The comprehensive analysis and calculation process of the computing control center includes:

[0040] (1) Film thickness calculation: For the No. 1 voltage measuring roller 13 and the No. 2 voltage measuring roller 14 on both sides of the No. 2 coating roller 7, the difference between the bias value applied by the first bias roller 11 or the second bias roller 12 and the voltage measurement value of the voltage measuring roller adjacent to the bias roller, as well as the flexible film path length between the bias roller and the corresponding voltage measuring roller, are used to calculate and analyze the conductive coating film thickness t1 of the surface of the flexible film in contact with the No. 1 voltage measuring roller and the conductive coating film thickness t2 of the surface of the flexible film in contact with the No. 2 voltage measuring roller; for the remaining voltage measuring rollers, the difference between the voltage measurement value of the No. m voltage measuring roller and the voltage measurement value of the (m-2) voltage measuring roller located on the same side of the flexible film as the No. m voltage measuring roller, as well as the flexible film path length between the two voltage measuring rollers, is used to calculate and analyze the conductive coating film thickness t m ;

[0041] (2) Calculation of coating roller bias value: Figure 2 As shown, for coating roller No. x, based on the voltage measurement values ​​of voltage measuring roller No. (x-1) and voltage measuring roller No. x, the initial bias value on coating roller No. x, and the thickness of conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the temperature and flow rate of the cooling medium in the coating roller No. x, and calculate the bias voltage value that needs to be applied to the coating roller No. x after regulation;

[0042] Among them, 2≤x≤n, 3≤m≤n; when x=2, t (x-2) is t0, and t0 indicates that there is no conductive coating on the surface of the flexible film at this location.

[0043] In the calculation of the bias value of the coating roller, it also includes establishing a cooling model for the flexible film when it passes around coating roller No. 1. Using this cooling model, the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No. 1 are accurately obtained through analytical simulation. The initial surface temperature T1 of the flexible film when it passes around coating roller No. 1 is related to the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No. 1. The accuracy of T1 is ±0.1°C.

[0044] The calculation of the bias value of the coating roller also includes establishing a cooling model for the flexible film when it is wound around the coating roller No. x; using this cooling model, the voltage measurement values ​​of the voltage measuring roller No. (x-1) and the voltage measuring roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the thickness of the base film of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the adhesion force F between the flexible film and the surface of the coating roller No. x related to the initial bias value on the coating roller No. x x .

[0045] The calculation of the bias value of the coating roller also includes the adhesion force F obtained by analytical simulation. x , as well as the temperature and flow rate of the cooling medium in the coating roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the initial surface temperature T of the flexible film when it is wound around the coating roller No. x. x , and then make the initial surface temperature T x The initial surface temperature T1 of the flexible film when it is wound around the coating roller No. 1 is taken as the control target, and the bias value that needs to be applied to the coating roller No. x after adjustment is accurately obtained through iterative calculation. x The judgment condition for consistency with T1 is that the difference between the two is no more than ±0.05℃.

[0046] like Figure 3 As shown in FIG. 1 , the physical structure of the cooling model of the flexible film when it is wound around the No. 1 coating roller is: the cooling medium 18 of the No. 1 coating roller—the surface 19 of the No. 1 coating roller—the electrical insulation layer 20—the base film 21 of the flexible film—the conductive coating layer 22. Figure 4 As shown, the physical structure of the cooling model of the flexible film when it is wrapped around the coating roller No. x is: cooling medium 23 of coating roller No. x—surface 24 of coating roller No. x—electrical insulation layer 25—conductive coating 26—base film 21 of the flexible film—conductive coating 27.

[0047] The calculation control center is pre-set with fixed parameters such as the flexible film path length between the rollers, the material properties of the conductive coating, the base film thickness of the flexible film, and the thickness of the electrical insulation layer of each coating roller. During the vacuum evaporation coating process, the calculation control center also obtains in real time the bias value on each coating roller, the original bias value applied on the conductive coating, the voltage measurement value from each voltage measuring roller, and the temperature and flow rate of the cooling medium in each coating roller. Then, through comprehensive calculation and analysis, the bias value to be applied to the coating rollers 2 to n is adjusted in real time, thereby adjusting the adhesion force of the flexible film on the coating rollers 2 to n, so that the initial surface temperature of the coating surface of the flexible film tends to be consistent when it passes through each coating roller. Specifically, firstly, based on the fixed parameters such as the flexible film path length between the rollers and the material properties of the conductive coating, as well as the process variable parameters such as the voltage measurement value of each voltage measuring roller, the thickness of the conductive coating layer of each section of the flexible film is calculated and analyzed. Then, a cooling model of the flexible film when it passes through the coating roller is established. The establishment of the cooling model fully considers the relative position relationship between the conductive coating and the flexible film base film in the physical structure and the changes in the thickness of the conductive coating at different coating stages. Then, the cooling model is used to combine the fixed parameters such as the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of each coating roller, as well as the process-varying parameters such as the voltage measurement value of each voltage measuring roller, the initial bias value on each coating roller, and the thickness of the conductive coating layer of each section of the flexible film to analyze and simulate the adhesion between the flexible film and the surface of each coating roller. Finally, the adhesion obtained by simulation is analyzed using the fixed parameters such as the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of each coating roller, as well as the process-varying parameters such as the temperature and flow rate of the cooling medium in each coating roller and the thickness of the conductive coating layer of each section of the flexible film to analyze and simulate the initial surface temperature T of the flexible film when it passes through each coating roller. x , and then make the initial surface temperature T x The control target is the initial surface temperature T1 of the flexible film when it is wound around the No. 1 coating roller, and the bias value that needs to be applied to each coating roller after regulation is accurately obtained through iterative calculation. xThe judgment condition consistent with T1 is that the difference between the two is no more than ±0.05°C. The voltage measuring roller accurately measures the voltage of each section of the flexible film and accurately controls the bias voltage on each coating roller in real time, thereby controlling the adhesion force of the flexible film on each coating roller, and then accurately controlling the initial surface temperature of the coating surface of the flexible film when it passes through each coating roller. The ultimate goal is to make the initial surface temperature of the coating surface of the flexible film tend to be consistent when it passes through each coating roller. When the fixed parameters of coating roller No. 1, such as the temperature and flow rate of the cooling medium, the bias value, or other process variable parameters, fluctuate, the computing control center in the winding coating equipment and method of the present invention can still adjust the positive bias voltage on each coating roller in time through real-time control, so that the initial surface temperature of the coating surface of the flexible film when it passes through each coating roller tends to be consistent. This consistency of initial surface temperature remains highly stable throughout the entire winding coating production process. The winding coating method of the present invention achieves high-precision consistency in the initial surface temperature of the coating surface of the flexible film when it is wound around each coating roller. When vacuum evaporation coating is performed on multiple coating rollers, the film-forming behavior of the material being deposited on the surface of the flexible film on each coating roller to generate a film layer is also highly consistent, so that the microstructural properties and film thickness of the conductive coating generated by multiple deposition processes on both sides of the front and back sides are also highly consistent and remain stable, ultimately making the film quality and electrical properties of the conductive coating on both sides of the flexible film show high consistency and stability, so that the composite current collector shows stable product performance and service life during long-term use.

[0048] When the flexible film is passed through coating rollers No. 1 to No. n in sequence, a layer of conductive coating material is deposited on one surface of the flexible film by vacuum evaporation coating each time it passes through a coating roller, so that the thickness of the conductive coating on the surface increases. When the flexible film completes the deposition of the last layer of conductive coating material on coating roller No. n, each surface of the flexible film has undergone n / 2 depositions of conductive coating material. At this time, the thickness of the conductive coating on the two surfaces is t n and t (n-1) , t n and t (n-1) All are in the range of 0.3 to 1.5 μm.

Claims

1. A roll-to-roll coating device, characterized in that: It comprises a vacuum system, a vacuum chamber and a computing control center; the vacuum system is used to evacuate the vacuum chamber; an unwinding roller, a winding roller and n coating rollers are arranged in the vacuum chamber, wherein n is an even number ranging from 4 to 10; the flexible film is unwound from the unwinding roller, and a conductive coating is deposited on the surface of the flexible film by vacuum evaporation coating when it is wound around the coating roller No. 1 to the coating roller No. n in sequence, and then it is wound up by the winding roller; a cooling medium is passed through the inside of the coating roller, and an electrical insulating layer is arranged on the outer surface of the coating roller; a first bias roller is arranged downstream of the coating roller No. 1, and is used to apply a negative bias voltage to the first surface of the flexible film on which the conductive coating has been deposited; a second bias roller is arranged downstream of the coating roller No. 2, and is used to apply a negative bias voltage to the second surface of the flexible film on which the conductive coating has been deposited; Except for coating roller No. 1, a voltage measuring roller is arranged on both sides of each coating roller, and they are numbered sequentially from voltage measuring roller No. 1 upstream of coating roller No. 2 to voltage measuring roller No. n downstream of coating roller No. n; the voltage measuring roller is used to measure the voltage of the surface of the flexible film in contact with the voltage measuring roller online; the computing control center applies a positive bias with an initial bias value on the surface of each coating roller in advance through a bias generating device; the computing control center obtains in real time the bias value on each coating roller, the bias value applied by the first bias roller and the second bias roller, the voltage measurement value from each voltage measuring roller, and the temperature and flow rate of the cooling medium in each coating roller, and then adjusts in real time the bias value to be applied to coating rollers No. 2 to No. n through comprehensive calculation and analysis.

2. The web coating equipment according to claim 1, characterized in that: The electrical insulation layer has good thermal conductivity and a thickness of 5 to 200 μm.

3. The web coating equipment according to claim 1, characterized in that: At least one evaporation source is arranged under each coating roller.

4. The web coating equipment according to claim 1, characterized in that: The bias values ​​of the positive bias voltage applied to each coating roller and the negative bias voltage applied by the first bias roller and the second bias roller have a bias value precision of 0.001V, and the measurement precision of the voltage measuring roller is 0.001V.

5. A roll-to-roll coating method based on the roll-to-roll coating device according to claim 1 or 2, characterized in that: When the flexible film is passed through two adjacent coating rollers, conductive coatings are deposited on two different surfaces of the flexible film respectively; The calculation control center presets the flexible film path length between the rollers and the material properties of the conductive coating; the comprehensive analysis and calculation process of the calculation control center includes: (1) Film thickness calculation: For the No. 1 voltage measuring roller and the No. 2 voltage measuring roller on both sides of the No. 2 coating roller, the difference between the bias value applied by the first bias roller or the second bias roller and the voltage measurement value of the voltage measuring roller adjacent to the bias roller, as well as the flexible film path length between the bias roller and the corresponding voltage measuring roller, are used to calculate and analyze the conductive coating film thickness t1 of the surface of the flexible film in contact with the No. 1 voltage measuring roller and the conductive coating film thickness t2 of the surface of the flexible film in contact with the No. 2 voltage measuring roller. For the remaining voltage measuring rollers, the difference between the voltage measurement value of the No. m voltage measuring roller and the voltage measurement value of the (m-2) voltage measuring roller located on the same side of the flexible film as the No. m voltage measuring roller, as well as the flexible film path length between the two voltage measuring rollers, are used to calculate and analyze the conductive coating film thickness t m ; (2) Calculation of the bias voltage value of the coating roller: For coating roller No. x, based on the voltage measurement values ​​of the voltage measuring roller No. (x-1) and the voltage measuring roller No. x, the initial bias voltage value on the coating roller No. x, and the thickness of the conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the temperature and flow rate of the cooling medium in the coating roller No. x, and calculate the bias voltage value that needs to be applied to the coating roller No. x after regulation; Among them, 2≤x≤n, 3≤m≤n; when x=2, t (x-2) is t0, and t0 indicates that there is no conductive coating on the surface of the flexible film at this location.

6. The winding coating method according to claim 5, characterized in that: In the calculation of the bias value of the coating roller, it also includes establishing a cooling model for the flexible film when it passes around coating roller No.

1. Using this cooling model, the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No. 1 are accurately obtained through analytical simulation. The initial surface temperature T1 of the flexible film when it passes around coating roller No. 1 is related to the bias value applied by the first bias roller, the bias value on coating roller No. 1, the thickness of the conductive coating layer t1, the base film thickness of the flexible film, the thickness of the electrical insulation layer on the surface of coating roller No. 1, and the temperature and flow rate of the cooling medium in coating roller No.

1. The accuracy of T1 is ±0.1°C.

7. The roll-to-roll coating method according to claim 5, characterized in that: The calculation of the bias value of the coating roller also includes establishing a cooling model for the flexible film when it is wound around the coating roller No. x; using this cooling model, the voltage measurement values ​​of the voltage measuring roller No. (x-1) and the voltage measuring roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the thickness of the base film of the flexible film, the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the adhesion force F between the flexible film and the surface of the coating roller No. x related to the initial bias value on the coating roller No. x x .

8. The winding coating method according to claim 7, characterized in that: The calculation of the bias value of the coating roller also includes the adhesion force F obtained by analytical simulation. x , as well as the temperature and flow rate of the cooling medium in the coating roller No. x, the thickness of the conductive coating layer t (x-2) and t (x-1) , the base film thickness of the flexible film and the thickness of the electrical insulation layer on the surface of the coating roller No. x, and the initial surface temperature T of the flexible film when it is wound around the coating roller No. x. X , and then taking the initial surface temperature Tx and the initial surface temperature T1 of the flexible film when it is wrapped around the coating roller No. 1 as the control target, the bias value that needs to be applied to the coating roller No. x after adjustment is accurately obtained through iterative calculation.

9. The winding coating method according to claim 6, characterized in that: The physical structure of the cooling model of the flexible film when it is wound around the No. 1 coating roller is: cooling medium - surface of the coating roller - electrical insulation layer - flexible film base film - conductive coating layer.

10. The roll-to-roll coating method according to claim 7, characterized in that: The physical structure of the cooling model of the flexible film when it is wound around the coating roller No. x is: cooling medium - surface of the coating roller - electrical insulation layer - conductive coating layer - flexible film base film - conductive coating layer.

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