A highly flexible polytetrafluoroethylene material and its preparation method

Abstract

This invention discloses a high-flexibility polytetrafluoroethylene (PTFE) material and its preparation method, belonging to the field of polymer material molding and processing. The preparation steps include: mixing PTFE powder with a wetting agent, pouring it into a cylindrical mold for molding to obtain a green compact, sintering the green compact, and when the temperature drops to a first temperature, taking it out and placing it in a rolling mill for rolling to obtain a cylindrical semi-finished product. The cylindrical semi-finished product is then placed in a first temperature for heat treatment, and then the cylindrical semi-finished product is taken out and clamped at both ends, subjected to axial vibration, and allowed to cool naturally to obtain the high-flexibility PTFE material. This invention utilizes the high melt index and high crystallinity of PTFE, combining rolling molding and vibration molding. This not only effectively eliminates the internal stress concentration during the molding process of PTFE material, but also ensures that the material has a high amorphous region under the winding of higher molecular chain segments, thereby ensuring that the PTFE material has both good frictional properties and excellent flexibility.

Description

Technical Field

[0001] This invention relates to a highly flexible polytetrafluoroethylene material and its preparation method, belonging to the field of polymer material molding and processing. Background Technology

[0002] With the rapid development of high-end technical equipment, high-pressure and high-temperature special working conditions place higher demands on the mechanical properties of polymer materials, such as flexibility and compression resilience, especially for industrial flange gaskets and highly flexible lip-type oil seals. Due to the requirements for corrosion resistance and good compression resilience, polytetrafluoroethylene (PTFE) resin materials have attracted much attention because of their excellent performance. However, PTFE has poor fatigue resistance and flexibility. When used as flange and oil seal materials, it is prone to fatigue damage due to excessive local stress, leading to flange gasket and oil seal failure and affecting the service life of equipment. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a high-flexibility polytetrafluoroethylene material and its preparation method, which makes the polytetrafluoroethylene material more flexible and less prone to fatigue damage.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] In a first aspect, this application provides a method for preparing a highly flexible polytetrafluoroethylene material, comprising the following steps:

[0006] Polytetrafluoroethylene powder is mixed with a wetting agent, poured into a cylindrical mold and molded to obtain a green body;

[0007] The sintered green billet is taken out and rolled in a rolling mill when the temperature drops to the first temperature to obtain a columnar semi-finished product;

[0008] The columnar semi-finished product is placed in a first temperature for heat treatment, then the columnar semi-finished product is taken out and its two ends are clamped, axial vibration is applied and it is naturally cooled to obtain a highly flexible polytetrafluoroethylene material.

[0009] Compared to traditional processes that involve furnace cooling of PTFE material after sintering, the preparation method provided in this application involves rolling and vibration processing of the material during cooling. This effectively reduces the cracking problem caused by stress concentration within the PTFE material during cooling, effectively increases the degree of molecular chain entanglement, and further increases the proportion of amorphous structure, reducing material hardness and improving material flexibility and elongation at break. The PTFE material prepared by this application exhibits high flexibility and high elongation, which can better meet the requirements of gaskets and high-speed oil seals operating under complex conditions.

[0010] Furthermore, the sintering temperature is 375℃~380℃, with the first temperature being 320℃.

[0011] This sintering temperature ensures that after the PTFE powder melts, the PTFE molecular chains from different particles intertwine to form the structure required for good mechanical properties, while avoiding material decomposition due to excessive temperature, ensuring molecular structure stability, and providing a guarantee for subsequent performance optimization.

[0012] Further, the sintering process is as follows: the temperature is raised to 200℃ at 110℃ / h and held for 10 min, then raised to 375℃~380℃ at 80℃ / h and held for 1 h, and finally lowered to 320℃ at 40℃ / h and held for 10 min, and then taken out for rolling; that is, the step of taking out and placing it in the rolling mill when the temperature drops to the first temperature is: after the "lowering to 320℃ at 40℃ / h and holding for 10 min" in the sintering process, it is taken out and placed in the rolling mill for rolling.

[0013] Furthermore, the rolling impact force is 3MPa~8MPa, the frequency is 2Hz~5Hz, and the rolling time is 5min.

[0014] Furthermore, the heat preservation treatment time is 10 minutes.

[0015] Rolling makes it difficult for polytetrafluoroethylene (PTFE) to crystallize stably, refines the grains, and enhances the entanglement of molecular chains. After rolling, the temperature of PTFE is brought back to 320°C for a short period of time, which slightly relaxes the molecular chains and releases the mild fatigue caused by rolling.

[0016] Furthermore, the vibration is a simple harmonic motion, which prevents stable crystallization inside the polytetrafluoroethylene material during the cooling process, thus forming a high-content amorphous structure material. Due to the low crystallinity of the material, it has good flexibility and low strength.

[0017] Further, in the steps of removing the columnar semi-finished product and clamping both ends, applying axial vibration and allowing it to cool naturally, the clamping makes the axial compression rate of the columnar semi-finished product 3%~7%, the amplitude of the axial vibration is 1% of the original axial length of the columnar semi-finished product, the applied frequency is 30Hz~100Hz, and the vibration duration is 30min~60min.

[0018] Furthermore, the wetting agent is at least one of polyethylene glycol, polyether modified silicone oil, fatty alcohol polyoxyethylene ether, polyoxyethylene alkylphenol ether, and fluorocarbon surfactant; in the step of mixing polytetrafluoroethylene powder with the wetting agent, the mass mixing ratio of polytetrafluoroethylene powder to wetting agent is 15:1, so that the raw material has good processability.

[0019] Furthermore, the compression molding pressure is 50MPa~110MPa, and the holding time is more than 30min.

[0020] Secondly, this application provides a high-flexibility polytetrafluoroethylene material, which is made by the high-flexibility polytetrafluoroethylene material preparation method of the first aspect. It has high elongation at break and flexibility, and can be used in long-term flange gaskets and rotary oil seal applications.

[0021] The beneficial effects of this invention are as follows: This invention utilizes the high melt index and high crystallinity of polytetrafluoroethylene (PTFE) by combining rolling and vibration molding. This not only effectively eliminates internal stress concentration during the PTFE material molding process but also ensures that the material has a high amorphous region under higher molecular chain segment winding. This, in turn, guarantees that the PTFE material possesses both excellent frictional properties and superior flexibility. PTFE prepared using this process exhibits strong flexibility and can effectively solve the problem of high heat generation in oil seals under high-speed operating conditions. Attached Figure Description

[0022] Figure 1 This is a cross-sectional electron microscope image of the polytetrafluoroethylene material prepared in Example 1.

[0023] Figure 2 This is a cross-sectional electron microscope image of the polytetrafluoroethylene material prepared in Comparative Example 3.

[0024] Figure 3 The graph shows the test results of crystallinity and elongation at break for each embodiment and comparative example.

[0025] Figure 4 This is a state diagram of the test of elongation at break in Example 1.

[0026] Figure 5 This is a diagram of the micro-vibration platform used in the embodiments and comparative examples. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0028] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0029] In this specification, groups and their substituents may be selected by those skilled in the art to provide stable structural moieties and compounds. When a substituent is described by a conventional chemical formula written from left to right, the substituent also includes chemically equivalent substituents obtained when the structural formula is written from right to left.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0031] To improve the poor flexibility of polytetrafluoroethylene (PTFE) materials

[0032] In this application, the highly flexible polytetrafluoroethylene material is prepared through the following process steps:

[0033] A certain amount of polytetrafluoroethylene powder and a certain amount of wetting solvent are mixed evenly at a mass ratio of 15:1 to give it good processability.

[0034] The mixed powder is poured into a cylindrical mold and pressed under pressure for 30 minutes before being removed. "Cylindrical" refers to shapes such as cylinders and prisms; it must be a straight cylinder, not an oblique one. For example, a disc-shaped piece is actually a cylinder with a relatively small height (geometrically), and therefore also belongs to the category of cylindrical shapes. Similarly, a cube-shaped piece is actually a prism with a relatively small height, and therefore also belongs to the category of cylindrical shapes.

[0035] The prepared materials are sintered and shaped in a sintering furnace according to a certain procedure, and held at the sintering temperature for a certain time to allow them to have sufficient molecular entanglement.

[0036] After the polytetrafluoroethylene (PTFE) material has completed its heat treatment during sintering, specifically, it is allowed to cool down to 320°C in the furnace and then held there for a certain period of time before being removed and placed on a rolling mill platform. The material is then rolled into shape for 5 minutes with a certain impact force and frequency. The rolling direction is axial, which makes the columnar material thicker and shorter (lower).

[0037] After the material is rolled, it is placed in a sintering furnace and kept at 320°C for 10 minutes. After the holding time is over, it is taken out and placed on a micro-vibration platform (or fixed to other equipment that can clamp the two ends of the columnar material and generate axial vibration). The two ends of the material (the two bases of the column in geometry) are fixed and given a certain initial compression rate. Vibration at a certain frequency is applied to cool and shape the material during the vibration process.

[0038] After the vibration molding process is completed, the material is removed to obtain highly flexible polytetrafluoroethylene material.

[0039] The resulting polytetrafluoroethylene material exhibits significantly reduced crystallinity, a fibrous internal structure, and high elongation at break and flexibility.

[0040] In this application, the wetting agent is one or more of polyethylene glycol, polyether-modified silicone oil, fatty alcohol polyoxyethylene ether, polyoxyethylene alkylphenol ether, and fluorocarbon surfactant.

[0041] In this application, the molding holding pressure is between 50 and 110 MPa. This holding pressure is based on the semi-crystalline properties of polytetrafluoroethylene (PTFE). If the pressure is too low, molding will be difficult, and if the pressure is too high, the PTFE material will easily slip and break, which is not conducive to subsequent molding.

[0042] In this application, the rolling impact force in the rolling process is 3MPa to 8MPa, and the frequency is 2Hz to 5Hz. During the cooling and crystallization process of polytetrafluoroethylene (PTFE), this rolling process can eliminate internal stress concentration while increasing the uniformity of molecular chain segment winding, thereby enhancing the material's flexibility. Experiments showed that, under the same initial conditions, if the rolling impact force is set to 20MPa, after rolling for 1 hour, the height of the cylindrical material becomes approximately 89% of its original value. Therefore, a rolling impact force of 3MPa to 8MPa is relatively small and will not cause fatigue damage to the material. Furthermore, during the heat treatment, the fatigue caused by rolling can be released.

[0043] In this application, the vibration molding process can be specifically referred to as a micro-vibration cooling process. During the material fixing process, the initial compression rate is 3%~7% (compressed to 93%~97% of the original height of the column), the applied amplitude is 1% (calculated based on the height before compression), the applied frequency is 30Hz~100Hz, and the vibration time is 30 minutes~60 minutes. During the cooling process of polytetrafluoroethylene (PTFE), the high-frequency external force prevents the molecular chain segments from crystallizing normally and promotes the enrichment of the amorphous phase. The high-frequency external force disrupts the stable crystallization conditions of PTFE, causing the material to shift towards a lower crystallinity transformation. Therefore, the molded material has lower crystallinity and flexibility.

[0044] In this application, the heating and cooling procedures in the sintering furnace are as follows:

[0045] The temperature is increased from room temperature to 200°C at a rate of 110°C / h and held for 10 minutes. Then, the temperature is increased to 375°C at a rate of 80°C / h and held for 1 hour. At this point, sintering is generally considered to be complete. The traditional method is to cool the furnace with the furnace. In this application, the temperature is decreased to 320°C at a rate of 40°C / h and held for 10 minutes before rolling.

[0046] In this application, the sintering temperature of polytetrafluoroethylene (PTFE) does not exceed 380℃, as excessively high temperatures will cause PTFE to decompose. To ensure the integrity of the PTFE molecular structure, its sintering temperature is set to no higher than 380℃. PTFE is significantly affected by temperature; therefore, the initial heating rate is 110℃ / h, the intermediate rate is 80℃ / h, and the final rate is 40℃ / h, fully considering the molecular chain entanglement and linear expansion effects at each stage, resulting in lower deformation.

[0047] This invention, considering the high crystallinity of polytetrafluoroethylene (PTFE), proposes a processing technique combining rolling and micro-vibration during the material crystallization process. The sintered PTFE molding material is initially rolled on a rolling mill during cooling, and then cooled and solidified using micro-vibration. Once the solidification process is complete, a highly flexible PTFE material is obtained. This method is simple and efficient, and the PTFE prepared by this method exhibits lower crystallinity and higher elongation at break, resulting in superior flexibility.

[0048] Example 1

[0049] This embodiment provides a preparation process for a highly flexible polytetrafluoroethylene material, the steps of which are as follows:

[0050] 1. Mix 1.5KG of polytetrafluoroethylene powder and 0.1KG of polyethylene glycol evenly using a mixer and set aside.

[0051] 2. Pour the polytetrafluoroethylene mixture prepared in step 1 into a 200mm cylindrical mold under normal pressure, set the molding press pressure to 110MPa and hold the pressure for 30 minutes. Set aside for later use after molding is complete.

[0052] 3. Place the PTFE blank molded in step 2 into a sintering furnace and sinter it according to the procedure, then allow it to cool down to 320℃. The specific sintering procedure is as follows:

[0053] The temperature is increased from room temperature to 200℃ at a rate of 110℃ / h and held for 10 minutes. Then, the temperature is increased to 375℃ at a rate of 80℃ / h and held for 1 hour. After sintering, the temperature is decreased to 320℃ at a rate of 40℃ / h and held for 10 minutes.

[0054] 4. Place the polytetrafluoroethylene cylindrical material sintered and cooled to 320℃ in step 3 onto a rolling mill, set the rolling pressure to 8MPa, the frequency to 2Hz, and the time to 5 minutes, and start the rolling process.

[0055] 5. After the rolling process in step 4 is completed, the PTFE cylindrical material is placed back into the sintering furnace and held at 320℃ for 10 minutes. After the holding period, the PTFE cylindrical material is removed and fixed on a micro-vibration platform, giving it an initial compression ratio of 7% and an amplitude of 1%, with a frequency of 30Hz and a duration of 30 minutes. The vibration program is then started to perform the micro-vibration forming process.

[0056] 6. After the micro-vibration molding process in step 5 is completed, remove it from the stand to obtain the highly flexible polytetrafluoroethylene material.

[0057] Example 2

[0058] This embodiment provides a preparation process for a highly flexible polytetrafluoroethylene material, the steps of which are as follows:

[0059] 1. Mix 1.5KG of polytetrafluoroethylene powder and 0.1KG of fatty alcohol polyoxyethylene ether evenly using a mixer and set aside.

[0060] 2. Pour the polytetrafluoroethylene mixture prepared in step 1 into a 200mm cylindrical mold under normal pressure, set the molding press pressure to 50MPa and hold the pressure for 30 minutes. Set aside for later use after molding is complete.

[0061] 3. Place the PTFE blank molded in step 2 into a sintering furnace and sinter it according to the procedure, then allow it to cool down to 320℃. The specific sintering procedure is as follows:

[0062] The temperature is increased from room temperature to 200℃ at a rate of 110℃ / h and held for 10 minutes. Then, the temperature is increased to 375℃ at a rate of 80℃ / h and held for 1 hour. After sintering, the temperature is decreased to 320℃ at a rate of 40℃ / h and held for 10 minutes.

[0063] 4. Place the polytetrafluoroethylene cylindrical material sintered and cooled to 320℃ in step 3 onto a rolling mill, set the rolling pressure to 3MPa, the frequency to 5Hz, and the time to 5 minutes, and start the rolling process.

[0064] 5. After the rolling process in step 4 is completed, the PTFE cylindrical material is placed back into the sintering furnace and held at 320℃ for 10 minutes. After the holding period, the PTFE cylindrical material is removed and fixed on a micro-vibration platform, giving it an initial compression ratio of 3% and an amplitude of 1%, with a frequency of 100Hz and a duration of 60 minutes. The vibration program is then started to perform the micro-vibration forming process.

[0065] 6. After the micro-vibration molding process in step 5 is completed, remove it from the stand to obtain the highly flexible polytetrafluoroethylene material.

[0066] Comparative Example 1

[0067] This comparative example provides a rolling process for preparing polytetrafluoroethylene, including the following steps:

[0068] 1. Mix 1.5KG of polytetrafluoroethylene powder and 0.1KG of fatty alcohol polyoxyethylene ether evenly using a mixer and set aside.

[0069] 2. Pour the polytetrafluoroethylene mixture prepared in step 1 into a 200mm cylindrical mold under normal pressure, set the molding press pressure to 80MPa and hold the pressure for 30 minutes. Set aside for later use after molding is complete.

[0070] 3. Place the PTFE blank molded in step 2 into a sintering furnace and sinter it according to the procedure, then allow it to cool down to 320℃. The specific sintering procedure is as follows:

[0071] The temperature is increased from room temperature to 200℃ at a rate of 110℃ / h and held for 10 minutes. Then, the temperature is increased to 375℃ at a rate of 80℃ / h and held for 1 hour. After sintering, the temperature is decreased to 320℃ at a rate of 40℃ / h and held for 10 minutes.

[0072] 4. Place the polytetrafluoroethylene cylindrical material sintered and cooled to 320℃ in step 3 onto a rolling mill, set the rolling pressure to 5MPa, the frequency to 4Hz, and the time to 5 minutes, and start the rolling process.

[0073] 5. After the rolling process in step 4 is completed, the polytetrafluoroethylene cylindrical material is placed back into the 320℃ sintering furnace, and the sintering furnace switch is turned off to allow the polytetrafluoroethylene material to cool with the furnace.

[0074] 6. After the furnace temperature in step 5 reaches room temperature, remove it from the sintering furnace to obtain a polytetrafluoroethylene material prepared by a rolling process.

[0075] Comparative Example 2

[0076] This comparative example provides a micro-vibration molding process for preparing polytetrafluoroethylene, including the following steps:

[0077] 1. Mix 1.5KG of polytetrafluoroethylene powder and 0.1KG of polyethylene glycol evenly using a mixer and set aside.

[0078] 2. Pour the polytetrafluoroethylene mixture prepared in step 1 into a 200mm cylindrical mold under normal pressure, set the molding press pressure to 110MPa and hold the pressure for 30 minutes. Set aside for later use after molding is complete.

[0079] 3. Place the PTFE blank molded in step 2 into a sintering furnace and sinter it according to the procedure, then allow it to cool down to 320℃. The specific sintering procedure is as follows:

[0080] The temperature is increased from room temperature to 200℃ at a rate of 110℃ / h and held for 10 minutes. Then, the temperature is increased to 375℃ at a rate of 80℃ / h and held for 1 hour. After sintering, the temperature is decreased to 320℃ at a rate of 40℃ / h and held for 10 minutes.

[0081] 4. After the polytetrafluoroethylene material from step 3 has been sintered and cooled to 320℃, it is removed and fixed on a micro-vibration platform, giving it an initial compression ratio of 7% and an amplitude of 1%. The frequency is set to 30Hz and the time to 30 minutes. The vibration program is then started to perform the micro-vibration molding process.

[0082] 5. After the micro-vibration molding process in step 4 is completed, remove it from the stand to obtain polytetrafluoroethylene material.

[0083] Comparative Example 3

[0084] This comparative example provides a process for preparing polytetrafluoroethylene using a cold pressing and sintering process, including the following steps:

[0085] 1. Mix 1.5KG of polytetrafluoroethylene powder and 0.1KG of polyethylene glycol evenly using a mixer and set aside.

[0086] 2. Pour the polytetrafluoroethylene mixture prepared in step 1 into a 200mm cylindrical mold under normal pressure, set the molding press pressure to 110MPa and hold the pressure for 30 minutes. Set aside for later use after molding is complete.

[0087] 3. Place the PTFE blank molded in step 2 into a sintering furnace and sinter it according to the procedure, while allowing it to cool down with the furnace. The specific sintering procedure is as follows:

[0088] The temperature is increased from room temperature to 200℃ at a rate of 110℃ / h and held for 10 minutes. Then, the temperature is increased to 375℃ at a rate of 80℃ / h and held for 1 hour. After sintering, the temperature is decreased to 320℃ at a rate of 40℃ / h and held for 10 minutes. The sintering furnace is then turned off to allow the polytetrafluoroethylene material to cool with the furnace.

[0089] 4. After the furnace temperature in step 3 reaches room temperature, remove it from the sintering furnace to obtain the polytetrafluoroethylene material prepared by the cold pressing sintering process.

[0090] In the above examples and comparative examples using micro-vibration molding, the micro-vibration platform used is as follows: Figure 5 As shown, the clamping direction is parallel to the vibration direction.

[0091] The cross-sections of the polytetrafluoroethylene (PTFE) materials prepared in Example 1 and Comparative Example 3 were observed using a scanning electron microscope. The results are as follows: Figure 1 and Figure 2 As shown.

[0092] The tensile properties of the polytetrafluoroethylene materials prepared in each embodiment and comparative example were tested; and their crystallinity was tested by DSC (differential scanning calorimetry). The results are shown in Table 1 and 2. Figure 3 As shown, the polytetrafluoroethylene material prepared in Example 1 exhibited the following characteristics when testing its elongation at break: Figure 4 As shown. Figure 3 In the graph, the bar chart represents crystallinity, and the arrow below "Crystallization" indicates that the crystallinity reading should be read from the left vertical axis; the curve chart represents elongation at break, and the arrow below "Elongation at break" indicates that the elongation at break reading should be read from the right vertical axis.

[0093] Table 1

[0094]

[0095] Electron microscopy revealed that after cold rolling and micro-vibration forming, the material exhibited distinct fibrous and amorphous regions. In contrast, the material without cold rolling and micro-vibration forming had a higher degree of crystallinity, resulting in less prominent fibers. The material treated with cold rolling and micro-vibration forming exhibited lower crystallinity and higher elongation at break. Compared to Comparative Example 3, Example 1 showed a 33.93% increase in elongation at break and a 32.95% decrease in crystallinity. Compared to Comparative Example 3, the materials prepared in Comparative Examples 1 and 2 showed increased flexibility, indicating that cold rolling and micro-vibration during the cooling process are beneficial for reducing crystallinity and enhancing flexibility, thereby improving the material's mechanical properties. The polytetrafluoroethylene formed according to the process of this invention exhibits higher flexibility, providing a basis for the research and application of highly flexible materials.

[0096] This application describes a process involving molding, sintering, cold rolling, and micro-vibration forming of polytetrafluoroethylene (PTFE). Molding allows for a small spatial entanglement between PTFE powder particles, enabling chain segment entanglement during sintering. Sintering allows the PTFE chains to intertwine, forming a material with a certain mechanical strength. Cold rolling primarily eliminates concentrated stress within the material during cooling and secondarily increases the degree of molecular chain segment entanglement, improving material flexibility. Micro-vibration forming prevents stable crystallization within the PTFE material during cooling, resulting in a high-content amorphous structure. Due to its lower crystallinity, the material exhibits higher flexibility and lower strength.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0098] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a highly flexible polytetrafluoroethylene material, characterized in that, Includes the following steps: Polytetrafluoroethylene powder is mixed with a wetting agent, poured into a cylindrical mold and molded to obtain a green body; The sintered green billet is taken out and placed in a rolling mill when the temperature drops to the first temperature. The rolling impact force is 3MPa~8MPa, the frequency is 2Hz~5Hz, and the rolling time is 5min to obtain a columnar semi-finished product. The columnar semi-finished product is placed in a first temperature for heat treatment, then the columnar semi-finished product is taken out and its two ends are clamped. The clamping makes the axial compression rate of the columnar semi-finished product 3%~7%. Axial vibration is applied and it is naturally cooled. The amplitude of the axial vibration is 1% of the original axial length of the columnar semi-finished product, the frequency is 30Hz~100Hz, and the vibration time is 30min~60min, to obtain a highly flexible polytetrafluoroethylene material.

2. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 1, characterized in that, The sintering temperature is 375℃~380℃, and the first temperature is 320℃.

3. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 2, characterized in that, The sintering process is as follows: the temperature is increased to 200℃ at 110℃ / h and held for 10 min, then increased to 375℃~380℃ at 80℃ / h and held for 1 h, and finally decreased to 320℃ at 40℃ / h and held for 10 min.

4. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 1, characterized in that, The heat preservation time is 10 minutes.

5. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 1, characterized in that, The vibration is a simple harmonic motion.

6. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 1, characterized in that, The wetting agent is at least one of polyethylene glycol, polyether modified silicone oil, fatty alcohol polyoxyethylene ether, polyoxyethylene alkylphenol ether, and fluorocarbon surfactant; in the step of mixing polytetrafluoroethylene powder with the wetting agent, the mass mixing ratio of polytetrafluoroethylene powder to wetting agent is 15:

1.

7. The method for preparing high-flexibility polytetrafluoroethylene material according to claim 1, characterized in that, The compression molding pressure is 50MPa~110MPa, and the holding time is more than 30min.

8. A highly flexible polytetrafluoroethylene material, characterized in that, It is made by the method for preparing the high-flexibility polytetrafluoroethylene material according to any one of claims 1 to 7.

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