Polytetrafluoroethylene microporous membrane, preparation method thereof, high-speed wire / high-speed communication cable and high-frequency copper-clad plate

Abstract

A preparation method of a polytetrafluoroethylene microporous membrane comprises the following steps: providing raw materials including polytetrafluoroethylene and a solvent; a stirrer is adopted to stir raw materials, the stirrer comprises a stirring tank and a stirrer arranged in the stirring tank, the stirring tank is provided with a longitudinal axis in the height direction of the stirring tank, when the stirrer stirs, the longitudinal axis of the stirring tank and an operation platform for placing the stirring tank form an included angle smaller than 90 degrees, and the stirring tank is controlled to rotate around the longitudinal axis; the temperature of the raw materials is controlled to be below 19 DEG C, the rotating speed of the stirrer is not higher than 2500 revolutions per minute, and the rotating speed of the stirring tank is not higher than 100 revolutions per minute; removing the solvent in the raw materials, and calcining; finely pulverizing the raw materials; the raw materials are made into a green body, and then the green body is subjected to rotary cutting / cutting to form the film. The polytetrafluoroethylene microporous membrane has low dielectric constant and low dielectric loss. The invention also provides the polytetrafluoroethylene microporous membrane prepared by the preparation method, a high-speed wire / high-speed communication cable and a high-frequency copper-clad plate.

Description

Technical Field

[0001] The present application relates to a polytetrafluoroethylene microporous membrane and a preparation method thereof, as well as a high-speed wire / high-speed communication cable and a high-frequency copper clad laminate including the polytetrafluoroethylene microporous membrane. Background Art

[0002] Polytetrafluoroethylene has excellent high-temperature resistance, good chemical stability (resistant to strong acids, strong alkalis, and organic solvents), and good electrical insulation properties. Therefore, the high-speed wire winding wrapping film made of polytetrafluoroethylene is a high-performance material widely used in the wire and cable industry, mainly used for the cable insulation layer. During the cable manufacturing process, the wrapping film is evenly wrapped around the cable core through a high-speed winding device to form one or more protective layers. This winding layer can not only prevent the cable from being mechanically damaged but also provide functions such as heat insulation, anti-corrosion, and anti-aging during the cable use process. Summary of the Invention

[0003] In view of this, the present application provides a polytetrafluoroethylene microporous membrane with a low dielectric constant and low dielectric loss, which has stable performance and can be applied to high-speed wires, high-speed communication cables, or high-frequency copper clad laminates.

[0004] The first aspect of the present application provides a preparation method of a polytetrafluoroethylene microporous membrane, including: S1: Providing raw materials, the raw materials including polytetrafluoroethylene and a solvent; S2: Stirring the raw materials by using a stirrer, the stirrer including a stirring tank and a stirrer disposed in the stirring tank, the stirring tank having a longitudinal axis along its height direction, when the stirrer stirs, the longitudinal axis of the stirring tank forms an angle less than 90 degrees with the operation platform on which the stirring tank is placed, controlling the stirring tank to rotate around the longitudinal axis, and controlling the temperature of the raw materials to be below 19°C, the rotation speed of the stirrer not being higher than 2500 revolutions per minute, and the rotation speed of the stirring tank not being higher than 100 revolutions per minute; S3: Removing the solvent from the stirred raw materials and performing calcination; S4: Finely pulverizing the calcined raw materials; and S5: Making the finely pulverized raw materials into a green body, and then rotary cutting / cutting the green body into a film.

[0005] The preparation method of the polytetrafluoroethylene microporous membrane of the present application adopts a special low-temperature stirring process, which can effectively disperse polytetrafluoroethylene and avoid polytetrafluoroethylene agglomeration. In addition, through calcination, fine pulverization, pressing into a green body, and rotary cutting / cutting into a film, a polytetrafluoroethylene microporous membrane with a low dielectric constant and low dielectric loss can be finally obtained. This polytetrafluoroethylene microporous membrane has stable performance and can be applied to high-speed wires or high-frequency copper clad laminates.

[0006] In some embodiments, the solvent includes an alcohol-based organic solvent, or the solvent includes water and an alcohol-based organic solvent. In the raw materials, the polytetrafluoroethylene is 60-90 parts by mass, and the solvent is 10-40 parts by mass.

[0007] In some embodiments, in S2, the longitudinal axis of the stirring tank forms an angle of 45-60 degrees with the operating platform. In some embodiments, in S2, the rotation speed of the stirring tank is 25-100 revolutions per minute, and the rotation speed of the stirrer is 500-2500 revolutions per minute.

[0008] In some embodiments, S2 includes: Perform low-temperature pretreatment on the raw materials to bring the temperature of the raw materials to 0°C or below; Pour the raw materials pretreated at low temperature into the stirring tank and stir.

[0009] In some embodiments, S3 includes: Volatilize and remove the solvent in the stirred raw materials; Heat up the raw materials from which the solvent has been removed to 340°C - 380°C and perform heat preservation and calcination; S4 further includes: Transfer the raw materials to a blender and stir at a stirrer rotation speed greater than 2500 revolutions per minute to obtain powdery raw materials; and Screen the powdery raw materials using a sieve and select raw materials with a particle size of 100 µm - 300 µm. In some embodiments, S5 includes: Fill the finely powdered raw materials into a mold and press them into a green body, controlling the pressure to be 30 MPa - 70 MPa; Heat up the green body to 355°C - 385°C for heat preservation sintering to form a body.

[0010] The second aspect of the present application provides a polytetrafluoroethylene microporous membrane, which is prepared by the above-mentioned preparation method of the polytetrafluoroethylene microporous membrane.

[0011] The third aspect of the present application provides a high-speed line / high-speed communication cable, including a conductor core wire and the above-mentioned polytetrafluoroethylene microporous membrane wrapped around the conductor core wire.

[0012] The fourth aspect of the present application provides a high-frequency copper clad laminate, including the above-mentioned polytetrafluoroethylene microporous membrane. Description of the Drawings

[0013] Figure 1Flow chart of the method for preparing the polytetrafluoroethylene microporous membrane according to the embodiment of the present application.

[0014] Figure 2 Schematic diagram of a blender according to an embodiment of the present application.

[0015] Figure 3 Schematic diagram of a green body according to an embodiment of the present application.

[0016] Main element symbol description: Blender 100, mixing tank 10, mixing shaft 20, agitator 30, driving device 40, Green body 51, rotating shaft 53. Detailed implementation manners

[0017] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. The data range values described in the present application should include the end values unless otherwise specified.

[0018] The present application provides a method for preparing a polytetrafluoroethylene microporous membrane. The polytetrafluoroethylene microporous membrane has various uses, for example, it can be used for fluid filtration. Please refer to Figure 1 , the method for preparing the polytetrafluoroethylene microporous membrane includes the following steps S1 to S5.

[0019] Step S1: Provide raw materials, the raw materials include polytetrafluoroethylene and a solvent, wherein polytetrafluoroethylene is the main component of the raw materials, and the weight ratio of polytetrafluoroethylene in the raw materials is greater than the weight ratio of the solvent in the raw materials.

[0020] In the embodiment of the present application, the solvent can be an alcohol organic solvent, such as ethanol, isopropanol, but not limited thereto. The solvent can also include water and an alcohol organic solvent.

[0021] In some embodiments, the ratio of polytetrafluoroethylene to the solvent in the raw materials is: 60-90 parts by mass of polytetrafluoroethylene and 10-40 parts by mass of the solvent, but not limited thereto.

[0022] Step S2: Use a blender to stir the raw materials at a low temperature.

[0023] Please refer to Figure 2, the blender 100 according to the embodiment of the present application includes a mixing tank 10, a mixing shaft 20 disposed in the mixing tank 10, and a mixer 30. The mixing tank 10 is used to accommodate materials and provide a mixing space for the materials. The mixing shaft 20 is rotatable, the mixer 30 rotates around the mixing shaft 20, and the mixer 30 directly contacts the materials to achieve mixing, dispersion, shearing, and homogenization of the materials. The mixing shaft 20 and the mixer 30 can be driven to rotate by a driving device 40 (such as a high-speed motor, a motor, etc.). The mixer 30 can be, for example, a paddle mixer, a turbine mixer, or an anchor mixer. In the embodiment of the present application, the mixer 30 is a paddle mixer. Generally, the direction of the mixing shaft 20 of the blender 100 is parallel to the longitudinal axis of the mixing tank 10 (along the height direction of the mixing tank 10). In this embodiment, the longitudinal axis of the mixing tank 10 overlaps with the mixing shaft 20.

[0024] Polytetrafluoroethylene itself has the characteristics of being difficult to disperse and easy to agglomerate, and the conventional blending process of polytetrafluoroethylene with organic solvents is also prone to causing agglomeration of organic solvents. Therefore, the embodiment of the present application adopts a special low-temperature stirring process to disperse the raw materials, which can effectively disperse polytetrafluoroethylene and avoid agglomeration. In the embodiment of the present application, low-temperature stirring means that the raw materials are stirred at a temperature below 19°C. In some embodiments, low-temperature stirring means that both the ambient temperature and the raw material temperature during step S2 stirring are below 19°C.

[0025] Polytetrafluoroethylene mainly has two crystal forms: triclinic and hexagonal. At temperatures below 19°C, polytetrafluoroethylene is in the triclinic form. When the temperature rises above 19°C, the triclinic polytetrafluoroethylene gradually transforms into hexagonal polytetrafluoroethylene. The crystal form transformation of polytetrafluoroethylene is reversible. It changes from the triclinic form to the hexagonal form when heated and returns to the triclinic form when cooled. Compared with triclinic polytetrafluoroethylene, hexagonal polytetrafluoroethylene has higher flexibility, the molecular chains are arranged loosely, and the material is softer.

[0026] Step S2 includes: performing low-temperature pretreatment on the raw materials to make the temperature of the raw materials reach 0°C or below; pouring the low-temperature pretreated raw materials into the mixing tank 10 of the blender 100 and stirring them through the mixer 30, and controlling the temperature of the raw materials to be below 19°C during stirring. In some embodiments, the temperature of the raw materials is controlled to be -5°C - 18°C during stirring, for example, specifically -5°C, -3°C, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C. In some embodiments, the temperature of the raw materials is controlled to be 0°C or below during stirring.

[0027] In the embodiments of the present application, when the stirrer 30 rotates to stir the raw materials, the stirring tank 10 is not vertically placed and stationary on the operating platform, but is inclined on the operating platform, that is, the longitudinal axis of the stirring tank 10 forms an angle less than 90 degrees with the operating platform, and the stirring tank 10 also rotates around its longitudinal axis. The inclined setting of the stirring tank 10 can ensure that the raw materials at all positions inside the stirring tank 10 can be stirred, and there is no un-stirred position. It can be understood that although not shown in the figure, the stirring tank 10 can be driven to rotate along its longitudinal axis by an additional driving device (such as a high-speed motor, a motor, etc.). The rotation speed of the stirring tank 10 is controlled not to exceed 100 revolutions per minute, and the rotation speed of the stirrer 30 is controlled not to exceed 2,500 revolutions per minute. In this way, by setting the stirring tank 10 inclined and combining with the specific rotation speeds of the stirrer 30 and the stirring tank 10, the stirring of the raw materials by the mixer 100 can be relatively more gentle, and the temperature of the raw materials in the stirring tank 10 will not rise rapidly.

[0028] In some embodiments, the longitudinal axis of the stirring tank 10 forms an angle of 45 - 60 degrees with the operating platform, for example, the angle is 45 degrees, 47 degrees, 50 degrees, 53 degrees, 55 degrees, 57 degrees, 60 degrees.

[0029] In some embodiments, the rotation speed of the stirring tank 10 is 25 - 100 revolutions per minute, for example, the rotation speed is 25 revolutions per minute, 35 revolutions per minute, 45 revolutions per minute, 55 revolutions per minute, 65 revolutions per minute, 75 revolutions per minute, 85 revolutions per minute, 95 revolutions per minute, 100 revolutions per minute.

[0030] In some embodiments, the rotation speed of the stirrer (blade) 30 is 500 - 2,500 revolutions per minute, for example, the rotation speed is 500 revolutions per minute, 600 revolutions per minute, 700 revolutions per minute, 900 revolutions per minute, 1,200 revolutions per minute, 1,500 revolutions per minute, 1,800 revolutions per minute, 2,000 revolutions per minute, 2,200 revolutions per minute, 2,500 revolutions per minute.

[0031] It can be understood that the high-speed stirring of the stirrer (blade) 30 will cause the temperature of the raw materials to rise. When the temperature rises above 19 °C, the stirring needs to be stopped. Wait until the temperature of the raw materials drops below 19 °C, and then continue the stirring. In short, during the stirring in step S2, the temperature of the raw materials is controlled not to exceed 19 °C.

[0032] If the raw materials include a solvent, when the stirring reaches a uniform mixture of polytetrafluoroethylene and the solvent, the stirring can be stopped, and step S2 is completed.

[0033] Before performing the subsequent step S3, the preparation method may further include: observing the state of the raw materials after stirring through a microscope, such as the case of a uniform state, and judging whether the requirements are met according to the case of the uniform state. If the requirements are met (for example, the uniform mixing of polytetrafluoroethylene and the solvent), step S2 is stopped and step S3 is performed. If the requirements are not met, step S2 is continued until the case of the uniform state of the raw materials meets the requirements.

[0034] Step S3: Remove the solvent from the raw materials after low-temperature stirring, and then perform calcination.

[0035] The solvent in the stirred raw materials can be removed by natural evaporation, or the raw materials can be heated to no more than 150 °C to remove the solvent. After removing the solvent, the raw materials include polytetrafluoroethylene.

[0036] The raw materials after removing the solvent are heated to a temperature of 340 °C - 380 °C and kept at a constant temperature for calcination for 2 - 8 hours. In step S3, the calcination temperature for heat preservation can be, for example, 340 °C, 345 °C, 350 °C, 355 °C, 360 °C, 365 °C, 370 °C, 375 °C, 380 °C, and the calcination time for heat preservation can be, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours.

[0037] High-temperature calcination causes small-molecular-weight polytetrafluoroethylene to be thermally degraded and volatilized and removed, and the molecular weight distribution of the remaining polytetrafluoroethylene becomes narrower (the molecular weights are more consistent). The polytetrafluoroethylene remaining after calcination can form a framework structure, and certain gaps will be formed when they are pressed and combined subsequently, which is convenient for forming a polytetrafluoroethylene microporous membrane using the calcined polytetrafluoroethylene subsequently.

[0038] Step S4: Pulverize the raw materials after calcination.

[0039] Step S4 includes: transferring the raw materials cooled to room temperature to a blender for high-speed stirring, and the rotation speed of the stirrer (blade) is greater than 2500 revolutions per minute. In some embodiments, the rotation speed of the stirrer (blade) is 2500 - 4000 revolutions per minute, and the stirring time is 5 - 10 minutes to obtain powdery raw materials. The polytetrafluoroethylene is broken into powder under the action of the shear stress of the stirrer (blade) and thus becomes powdery raw materials. It can be understood that the method of breaking polytetrafluoroethylene into powder is not limited to the way of stirring with a stirrer, and can also be various other ways used in this field.

[0040] Step S4 further includes: screening the powdery raw materials with a sieve to control the particle size of the screened raw materials to be 100 µm - 300 µm.

[0041] In step S4, the stirrer rotates at a relatively high speed, and the polytetrafluoroethylene is broken into powdery particles under the shearing stress of the stirrer (blade). The powdery particles facilitate the subsequent pressing of the raw materials into a solid green body.

[0042] In step S4, the rotation speed of the stirrer (blade) can be 2550 revolutions per minute, 2600 revolutions per minute, 2620 revolutions per minute, 2650 revolutions per minute, 2700 revolutions per minute, 2750 revolutions per minute, 2800 revolutions per minute, and the stirring time is 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes.

[0043] Step S5: The finely powdered raw materials are made into a green body through pressing and sintering, and then the green body is turned / machined into a film.

[0044] In some embodiments, as Figure 3 shown, the green body 51 is a hollow cylindrical shape, and a through hole is formed through it in the green body 51.

[0045] Step S5 includes: (1) Using a mold, filling the powdery raw materials into the mold and pressing them into a green compact; (2) Heating the green compact, and performing heat preservation sintering after reaching the required sintering temperature to form a green body; (3) Turning / machining the green body to form a polytetrafluoroethylene microporous membrane with a certain thickness.

[0046] In some embodiments, an oil press can be used to press the green compact, controlling the pressure to be 30 MPa - 70 MPa and the pressure holding time to be 10 - 30 minutes. Controlling the pressing pressure to be 30 MPa - 70 MPa can not only ensure that the green compact is pressed into shape, but also ensure that there are certain gaps between the polytetrafluoroethylene particles to form micropores. For example, the pressure can be 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, and the pressure holding time is 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes.

[0047] In some embodiments, when preparing the green compact, the powdery raw materials are put into the mold, and the raw materials are pressed into a hollow cylindrical green compact, and a through hole is formed through the green compact, and the through hole is cylindrical.

[0048] After the green compact is demolded from the mold, it is transferred to a sintering device (such as a sintering furnace) for sintering. During the sintering process, the surface parts of the polytetrafluoroethylene particles are partially melted and combined with each other to form a relatively dense green body. Compared with the green compact, the sintered green body has a higher density and mechanical strength, the internal structure of the green body is uniform, it is suitable for subsequent machining, and there are multiple micropores inside the green body.

[0049] In some embodiments, the cross-sectional diameter of the through-hole is 40 - 200 mm, the cross-sectional diameter of the green body is 250 - 350 mm, and the height of the green body is 500 mm.

[0050] In some embodiments, the sintering temperature can be 355°C - 385°C, and the holding time can be 10 - 30 hours. For example, the sintering temperatures are 355°C, 360°C, 365°C, 370°C, 375°C, 380°C, 385°C, and the holding times can be 10 hours, 12 hours, 15 hours, 17 hours, 20 hours, 23 hours, 25 hours, 27 hours, 30 hours. The holding time for sintering can be adjusted accordingly according to the wall thickness of the hollow green body.

[0051] As Figure 3 shown, when turning / cutting into a film, a rotating shaft 53 is pushed into the through-hole of the green body 51, and both ends of the rotating shaft 53 protrude relatively from the green body 51. The rotating shaft 53 is cylindrical, and the rotating shaft 53 can be used as the rotating shaft for subsequent turning / cutting to drive the green body 51 to rotate. The material of the rotating shaft 53 can be a metal material, such as steel.

[0052] In some embodiments, when turning / cutting the green body into a film, a numerically controlled lathe can be used. The numerically controlled lathe includes a rotating worktable and a high-precision cutting tool. The rotating shaft and the green body are fixed on the rotating worktable. The rotating shaft rotates at a certain speed to drive the green body to rotate, and the cutting tool cuts the outer layer of the green body. In this way, as the rotating shaft rotates, the green body is cut into a polytetrafluoroethylene microporous film with a uniform thickness, and the cut polytetrafluoroethylene microporous film is wound up. In some embodiments, the rotation speed of the rotating shaft is set to 2 - 10 m / minute, and the thickness of the cut polytetrafluoroethylene microporous film is 0.05 mm - 0.15 mm. The method for preparing the polytetrafluoroethylene microporous film according to the embodiments of the present application adopts a special low-temperature stirring process, which makes the polytetrafluoroethylene evenly dispersed, avoids agglomeration, and through calcination, fine powdering, pressing into a green body, and turning / cutting into a film, finally a polytetrafluoroethylene microporous film with a low dielectric constant and low dielectric loss can be obtained. The performance of the polytetrafluoroethylene microporous film is stable and can be applied to high-speed lines or high-frequency copper clad laminates.

[0053] The embodiments of the present application also provide a polytetrafluoroethylene microporous film prepared by the above preparation method, which includes polytetrafluoroethylene. The polytetrafluoroethylene microporous film has a low dielectric constant and low dielectric loss. The dielectric constant of the polytetrafluoroethylene microporous film is lower than 2.2, for example, the dielectric constant is 2.0. The dielectric loss of the polytetrafluoroethylene microporous film is 0.0001 - 0.0005.

[0054] The density of the polytetrafluoroethylene microporous film is relatively low. In some embodiments, the density of the polytetrafluoroethylene microporous film is 1.2 g / cm 3 - 1.8 g / cm 3The tensile strength of the polytetrafluoroethylene microporous membrane is 5 MPa - 25 MPa, and the elongation at break is 40% - 300%.

[0055] The polytetrafluoroethylene microporous membrane of the embodiment of the present application can be used as a material for forming a high-frequency copper clad laminate. The embodiment of the present application also provides a high-frequency copper clad laminate, including the above-mentioned polytetrafluoroethylene microporous membrane. A high-frequency copper clad laminate is a multilayer board made by laminating a copper foil on an insulating substrate, and is suitable for high-frequency (usually ≥ 1 GHz) and high-speed signal transmission. Since the polytetrafluoroethylene microporous membrane of the embodiment of the present application has a low dielectric constant (Dk) and a low dielectric loss (Df), it can be used as a material for the insulating substrate of a high-frequency copper clad laminate.

[0056] The polytetrafluoroethylene microporous membrane of the embodiment of the present application can also be a material for forming a high-speed line or a high-speed communication cable. The high-speed line can be used in the servers of a data center. The embodiment of the present application also provides a high-speed line or a high-speed communication cable, including a conductor core wire and an insulating material layer wrapped around the conductor core wire. The insulating material layer can be formed by winding the polytetrafluoroethylene microporous membrane around the conductor core wire through a winding device. The insulating material layer can not only prevent the conductor core wire from being mechanically damaged, but also provide functions such as heat insulation, corrosion prevention, and anti-aging for the conductor core wire.

[0057] The insulating material layer formed by the polytetrafluoroethylene microporous membrane has excellent high-temperature resistance, excellent chemical stability (resistant to strong acids, strong bases, and organic solvents), and good electrical insulation performance.

[0058] The preparation method of the polytetrafluoroethylene microporous membrane of the present application adopts a special low-temperature stirring process, which can effectively disperse polytetrafluoroethylene and avoid agglomeration of polytetrafluoroethylene. In addition, a green body is formed through calcination, pulverization, pressing, and sintering, and then formed into a film by turning / cutting, and finally a polytetrafluoroethylene microporous membrane with a low dielectric constant and a low dielectric loss can be obtained. The polytetrafluoroethylene microporous membrane has stable performance and can be applied to high-speed lines or high-frequency copper clad laminates.

[0059] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a polytetrafluoroethylene microporous membrane, characterized in that, Comprising: S1: Providing raw materials, where the raw materials include polytetrafluoroethylene and a solvent; S2: Using a blender to stir the raw materials. The blender includes a stirring tank and a stirrer disposed in the stirring tank. The stirring tank has a longitudinal axis along its height direction. When the stirrer is stirring, the longitudinal axis of the stirring tank forms an angle less than 90 degrees with the operating platform on which the stirring tank is placed. Control the stirring tank to rotate around the longitudinal axis, and control the temperature of the raw materials to be below 19°C. The rotation speed of the stirrer is not higher than 2500 revolutions per minute, and the rotation speed of the stirring tank is not higher than 100 revolutions per minute; S3: Removing the solvent from the stirred raw materials and performing calcination; S4: Finely pulverizing the calcined raw materials; and S5: Forming the finely pulverized raw materials into a green body, and then turning / cutting the green body into a film.

2. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, wherein, The solvent includes an alcohol-based organic solvent, or the solvent includes water and an alcohol-based organic solvent. In the raw materials, the polytetrafluoroethylene is 60 - 90 parts by mass, and the solvent is 10 - 40 parts by mass.

3. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, characterized in that, In S2, the longitudinal axis of the stirring tank forms an angle of 45 - 60 degrees with the operating platform.

4. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, characterized in that, In S2, the rotation speed of the stirring tank is 25 - 100 revolutions per minute, and the rotation speed of the stirrer is 500 - 2500 revolutions per minute.

5. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, characterized in that, S2 includes: Performing low-temperature pretreatment on the raw materials to make the temperature of the raw materials reach 0°C or below; Pouring the raw materials after low-temperature pretreatment into the stirring tank for stirring.

6. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, wherein, S3 includes: Removing the solvent from the stirred raw materials; Raising the temperature of the raw materials after removing the solvent to 340°C - 380°C and performing heat preservation calcination; S4 further includes: Transferring the raw materials to the blender for stirring, with the rotation speed of the stirrer being greater than 2500 revolutions per minute to obtain powdered raw materials; and Sieving the powdered raw materials using a sieve and selecting raw materials with a particle size of 100 µm - 300 µm.

7. The preparation method of the polytetrafluoroethylene microporous membrane according to claim 1, characterized in that, S5 includes: Filling the finely pulverized raw materials into a mold and pressing them into a green body, controlling the pressure to be 30 MPA - 70 MPA; Raising the temperature of the green body to 355°C - 385°C for heat preservation sintering to form a green body.

8. A polytetrafluoroethylene microporous membrane, characterized in that, The polytetrafluoroethylene microporous membrane is prepared by the preparation method of the polytetrafluoroethylene microporous membrane according to any one of claims 1 to 7.

9. A high-speed wire / high-speed communication cable, characterized in that, Comprising a conductor core wire and the polytetrafluoroethylene microporous membrane according to claim 8 wrapped around the conductor core wire.

10. A high-frequency copper clad laminate, characterized in that, Comprising the polytetrafluoroethylene microporous membrane according to claim 8.

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