Longitudinal stretching machine suitable for dry-method diaphragm production

Abstract

The utility model provides a longitudinal stretcher suitable for dry-method diaphragm production, which is used for heating a plurality of layers of precursor films along the production direction and longitudinally stretching the precursor films to form dry-method diaphragms, and comprises a heating component, a plurality of roller units and a plurality of driving units, the heating assembly is used for heating the precursor film; the multiple roller units are arranged at intervals in the production direction, a preset tangent distance is formed between every two adjacent roller units, and each roller unit has a preset wrap angle; the multiple driving units are connected with the multiple roller units in a one-to-one correspondence mode, the driving units are used for driving the roller units to rotate at the preset linear speed, the linear speeds of the multiple roller units in the production direction are sequentially increased, and the speed difference between every two adjacent roller units does not exceed the preset range. The longitudinal stretching machine provided by the utility model can realize stable production of dry-method diaphragms without wrinkles.

Description

Technical Field

[0001] This utility model relates to the field of dry diaphragm production technology, and more specifically, to a longitudinal stretching machine suitable for dry diaphragm production. Background Technology

[0002] Dry-process separator production requires first using film-forming equipment, such as casting machines and blown film machines, to produce a precursor film with a certain orientation. Then, the precursor film undergoes online or offline heat treatment processes, followed by a stretching process to stretch the crystal sheets of the precursor film to a certain extent, creating pores between the crystal sheets and controlling the size of the pores. This results in a membrane with pore sizes between 10-50 nm, providing a certain degree of air permeability, which is then used in lithium batteries.

[0003] The online heat treatment and stretching processes described above, in order to improve production efficiency, allow precursor films with a thickness of 2-50µm to be stacked in 1-40 layers. During the longitudinal stretching process, the film is heated, and the speed difference between the rollers is used to stretch the multi-layered precursor film. In traditional longitudinal stretching machines, the film surface is simultaneously affected by thermal expansion and contraction due to temperature changes, and by deformation of the film in the longitudinal, transverse, and thickness directions caused by the speed difference between the rollers. The precursor film is easily affected by the combined effects of these two factors, leading to wrinkles on the film surface and affecting production yield.

[0004] In existing technologies, longitudinal stretching machines used for production are purchased in advance. Generally, the production yield is improved by modifying the dry diaphragm production process. However, for some process parameters, since the structure of the longitudinal stretching machine is fixed and cannot be adjusted, in some cases, no matter how the process parameters are adjusted, the production yield cannot be improved. Utility Model Content

[0005] (a) Technical problems to be solved

[0006] The technical problem this invention aims to solve is that wrinkles easily occur on the film surface when the existing longitudinal stretching machine stretches the film, affecting the production yield.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0009] This utility model provides a longitudinal stretching machine suitable for dry-process diaphragm production, used to heat and longitudinally stretch multilayer precursor films along the production direction to form dry-process diaphragms. The machine includes a heating assembly, multiple roller units, and multiple drive units. The heating assembly heats the precursor film. The multiple roller units are spaced apart along the production direction, wherein adjacent roller units have a preset tangential distance, and each roller unit has a preset wrap angle. The multiple drive units are connected one-to-one with the multiple roller units, and each drive unit drives the roller units to rotate at a preset linear speed. The linear speeds of the multiple roller units along the production direction increase sequentially, and the speed difference between adjacent roller units does not exceed a preset range.

[0010] Preferably, the tangent distance is less than or equal to 80% of the width of the precursor film.

[0011] Preferably, the wrap angle is 30° to 240°.

[0012] Preferably, the preset range is -5% to +5%.

[0013] Preferably, the width of the roller unit is greater than or equal to 110% of the width of the precursor film.

[0014] Preferably, the heating temperature of the heating component is 70℃~180℃.

[0015] Preferably, the number of roller units is 1 to 20.

[0016] Preferably, the heating component is a heating unit connected to the roller unit, or an oven.

[0017] Preferably, the roller unit is a single roller or a pair of rollers.

[0018] Preferably, the roller unit is a steel roller or a hard rubber roller.

[0019] (III) Beneficial Effects

[0020] The above-mentioned technical solution of this utility model has at least the following advantages:

[0021] In this invention, by standardizing the various design parameters of the longitudinal stretching machine, the problem of wrinkles easily occurring on the film surface during the longitudinal stretching process can be solved. The dry-process diaphragm produced by the longitudinal stretching machine with specific design parameters of this invention has a wrinkle-free film surface, which can improve the production yield of dry-process diaphragms. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural schematic diagram of the longitudinal stretching machine provided in this embodiment of the utility model.

[0024] Figure 2 This is a schematic diagram of the wrap angle of the longitudinal stretching machine provided in this embodiment of the utility model.

[0025] Figure 3 This is a test data table of dry-process diaphragms produced by the longitudinal stretching machine provided in this embodiment of the utility model.

[0026] The labels for the attached figures are as follows:

[0027] 10. Precursor membrane; 20. Dry-process separator; Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0029] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0030] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this utility model is described in more detail below with reference to specific embodiments:

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, Figure 1 In this embodiment, multiple sets of rollers are used to longitudinally stretch the precursor film 10. There are 20 lower rollers, numbered S1, S2…S20, and 20 upper rollers, numbered J1, J2…J20. This embodiment provides a longitudinal stretching machine suitable for dry-process diaphragm production, used to heat and longitudinally stretch a multi-layer precursor film 10 along the production direction to form a dry-process diaphragm 20. It includes a heating assembly, multiple roller units, and multiple drive units (not shown). The heating assembly heats the precursor film. The multiple roller units are spaced apart along the production direction, with adjacent roller units having a preset tangential distance and each roller unit having a preset wrap angle. Multiple drive units are connected one-to-one with the multiple roller units, driving the roller units to rotate at a preset linear speed. The linear speed of the multiple roller units increases sequentially along the production direction, and the speed difference between adjacent roller units does not exceed a preset range. Specifically, the drive unit is a rotary motor, and the specifications and model of the motor can be selected according to specific usage requirements.

[0033] In one embodiment, the tangent distance is less than or equal to 80% of the width of the precursor film.

[0034] In one embodiment, the wrap angle is 30° to 240°. Specifically, the wrap angle is illustrated as follows: Figure 2 As shown. Specifically, when the wrap angle is within this range, the diaphragm moves more smoothly, thus ensuring that the diaphragm is less prone to wrinkles during production.

[0035] In one embodiment, the preset range is -5% to +5%. Specifically, the speed difference between two adjacent roller units should not be too large and needs to be controlled within the preset range to avoid diaphragm wrinkling due to excessive speed difference.

[0036] In one embodiment, the width of the roller unit is greater than or equal to 110% of the width of the precursor film. The width of the roller unit must be no less than 110% of the width of the precursor film to ensure that the roller unit can fully support the entire precursor film, thereby preventing wrinkles from occurring due to lack of support.

[0037] In one embodiment, the heating temperature of the heating element is 70°C to 180°C. Specifically, the heating temperature of the heating element can be determined according to the actual production needs and process requirements. This embodiment only provides a preferred temperature range and does not limit the actual temperature range.

[0038] In one embodiment, the number of roller units is 1 to 20. Specifically, the number of roller units can be determined according to the actual needs of use. Theoretically, the more roller units there are, the better the quality of the final product. However, in actual use, the space occupied by multiple roller units needs to be considered. Therefore, a preferred range is 1 to 20 sets.

[0039] In one embodiment, the heating component is a heating unit connected to the roller unit, or an oven. The heating unit generates heat and conducts it to the roller unit, thereby achieving its heating function. The heating of the film may take the form of roller heating, space heating, or a combination of roller heating and space heating to transfer heat to the precursor film. Roller heating includes electrically heated rollers, kerosene-heated rollers, steam-heated rollers, etc., meaning the heating unit includes, but is not limited to, electrically heated units, kerosene-heated units, and steam-heated units. Space heating involves enclosing the precursor film or the precursor film and rollers in a fixed space, heating the air in the space, and then transferring the heat to the film surface.

[0040] In one embodiment, the roller unit is a single roller or a pair of rollers. The specific choice can be made according to the needs of the production process.

[0041] In one embodiment, the roller unit is a steel roller or a hard rubber roller.

[0042] like Figure 3 As shown, the illustrated embodiment uses 12 pairs of rollers to longitudinally stretch the film. The roller film width and the tangential distance between rollers are designed as shown in the table. Throughout the production process, the heating temperature is 150°C, the speed difference between two adjacent roller units is 1%, and the wrap angle is 110°. Production testing revealed that the dry-process separator produced in the above embodiment did not exhibit wrinkles, demonstrating good production stability. Figure 3 The test results show that when the tangential distance between two adjacent rollers is less than or equal to 84% of the width of the precursor film, the diaphragm will not wrinkle. When the tangential distance between two adjacent rollers is greater than 84% of the width of the precursor film, wrinkles will form on the diaphragm. Therefore, in this embodiment, to avoid wrinkles on the diaphragm, the tangential distance between two adjacent rollers is preferably less than or equal to 80% of the width of the precursor film.

[0043] It should be noted that the longitudinal stretching machine for dry-process diaphragm production provided in this embodiment is only applicable to the preparation of dry-process diaphragms and may not be applicable to diaphragms produced by other methods. Specifically, before actual production, the design parameters in this embodiment can be provided to the relevant equipment manufacturers, who can then customize the corresponding longitudinal stretching machine based on these parameters. The longitudinal stretching machine provided in this embodiment can effectively improve the product yield of dry-process diaphragms during the production process.

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A longitudinal stretching machine suitable for dry-process diaphragm production, used to heat and longitudinally stretch multilayer precursor films along the production direction to form dry-process diaphragms, characterized in that, include: A heating assembly for heating the precursor membrane; Multiple roller units are arranged at intervals along the production direction, wherein two adjacent roller units have a preset tangential distance, and each roller unit has a preset wrap angle. Multiple drive units are connected one-to-one with multiple roller units. Each drive unit drives the roller unit to rotate at a preset linear speed. The linear speed of the multiple roller units increases sequentially along the production direction, and the speed difference between two adjacent roller units does not exceed a preset range.

2. The longitudinal stretching machine for dry-process diaphragm production as described in claim 1, characterized in that, The tangent distance is less than or equal to 80% of the width of the precursor film.

3. The longitudinal stretching machine for dry-process diaphragm production as described in claim 1, characterized in that, The wrap angle is 30° to 240°.

4. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The preset range is -5% to +5%.

5. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The width of the roller unit is greater than or equal to 110% of the width of the precursor film.

6. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The heating temperature of the heating component is 70℃~180℃.

7. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The number of roller units is 1 to 20.

8. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The heating component is a heating unit connected to the roller unit, or an oven.

9. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The roller unit is a single roller or a pair of rollers.

10. The longitudinal stretching machine for dry diaphragm production as described in claim 1, characterized in that, The roller unit is a steel roller or a hard rubber roller.

Images