High-flexibility fluoroplastic and preparation method thereof

Abstract

The invention discloses high-flexibility fluoroplastic and a preparation method thereof. The raw materials comprise 50 to 80 parts of fluoroplastic, 20 to 50 parts of softening master batch, 0.2 to 1.0 part of a lubricant and 0.1 to 0.5 part of an antioxidant. The softening master batch is prepared from 50-70 parts of THV, 30-50 parts of fluororubber, 1-1.5 parts of a vulcanizing agent and 0.4-0.6 part of an accelerant through a two-step process: firstly plastifying the fluororubber, granulating with a vulcanizing aid at 80-90 DEG C, and then dynamically vulcanizing with THV for 2.5-4 minutes in a double-screw extruder with the length-diameter ratio of 36-40, the temperature of 150-185 DEG C and the rotating speed of 50-150rpm. After the master batch is mixed with auxiliaries such as fluoroplastic, melt extrusion is performed at the temperature of 180-360 DEG C, and the fluoroplastic with the flexibility remarkably improved can be obtained and is suitable for flexible modification and application of high-rigidity fluoroplastic such as PVDF, PCTFE, ETFE and ECTFE.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluoroplastic modification, in particular to a high-flexibility fluoroplastic and a preparation method thereof. BACKGROUND

[0002] Fluoroplastics are a general term for high molecular compounds containing fluorine in the main chain. Due to their excellent heat resistance, chemical corrosion resistance, insulation and low surface energy, they have become an indispensable key material in high-end fields such as national defense, aerospace, electronics, semiconductors, etc. However, some fluoroplastics represented by polyvinylidene fluoride (PVDF) and polychlorotrifluoroethylene (PCTFE) have high strength, but their flexibility (flexibility) is insufficient, which seriously limits their application in fields such as flexible pipes, high-performance seals, wire and cable, and flexible electronic devices that require high material flexibility.

[0003] To improve the flexibility of plastics, adding rubber or elastomer is a common and effective method. Fluororubber is considered an ideal toughening modification component due to its similar chemical structure to fluoroplastics and excellent medium resistance. However, fluororubber needs to be crosslinked to fully exhibit its elastomer properties. If uncrosslinked fluororubber is directly blended with fluoroplastics, it is easy to cause degradation of fluororubber during processing, and it is difficult to achieve uniform dispersion and effective crosslinking in the matrix, resulting in poor performance of the composite material. Therefore, how to achieve uniform dispersion and controllable crosslinking of fluororubber in the fluoroplastic matrix is the key to preparing high-flexibility fluoroplastic composites.

[0004] Dynamic vulcanization technology is one of the effective ways to solve the above problems, which can achieve crosslinking of the rubber phase during mixing, thereby obtaining a thermoplastic elastomer that can be melt processed. In the prior art, invention patent CN103396639B discloses a method for preparing a fluoroplastic / fluororubber / silicone rubber thermoplastic elastomer by dynamic vulcanization. Although this technology can obtain a material with both chemical resistance and repeatable processing, it still has obvious limitations: first, the fluoroplastic content in the system is low, which makes the overall performance of the material more biased towards rubber, and it lacks strength and surface hardness; second, the process requires high processing temperature and long processing time, under which additives are easily decomposed and the rubber phase is easily scorch, making it difficult to ensure the stability of product performance.

[0005] Tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (THV) as a new type of fluoroplastic provides a new idea for the blending modification with fluororubber due to its inherent high flexibility and relatively wide processing temperature window (160℃~185℃). The processing temperature of THV is highly consistent with the suitable vulcanization temperature range of fluororubber, which creates unique conditions for directly preparing a "flexibility-enhancing masterbatch" with good compatibility, melt processability and crosslinked rubber phase through a one-step dynamic vulcanization process.

[0006] In summary, the prior art fails to take full advantage of the characteristics of THV fluoroplastic, and there are deficiencies in terms of considering the material fluoroplastic intrinsic performance (high strength, high hardness) and efficient and stable processing technology. Therefore, the present application aims to provide a new solution to overcome the above-mentioned defects. SUMMARY

[0007] The purpose of the present application is to provide a high flexibility fluoroplastic and a preparation method thereof.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0009] A high flexibility fluoroplastic, the raw materials of which include the following components in parts by weight:

[0010] Fluoroplastic 80~50 parts;

[0011] Flexibility-improving masterbatch 20~50 parts;

[0012] Lubricant 0.2~1.0 parts;

[0013] Antioxidant 0.1~0.5 parts.

[0014] Further technical solutions, the fluoroplastic is one or more of polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyperfluoroalkyl alkoxy resin (PFA).

[0015] Further technical solutions, the lubricant is a mixture of one or more of zinc stearate, calcium stearate, polytetrafluoroethylene powder, fluorine-containing processing aid PPA, ethylene bis-stearyl amide (EBS), and high-temperature-resistant silicone powder.

[0016] Preferably, the lubricant is a mixture of one or more of fluorine-containing processing aid PPA, polytetrafluoroethylene powder, ethylene bis-stearyl amide (EBS), and high-temperature-resistant silicone powder.

[0017] Further preferably, the lubricant is a mixture of fluorine-containing processing aid PPA and high-temperature-resistant silicone powder; the effective ingredient content of the fluorine-containing processing aid PPA is ≥95%, the organic silicon content of the high-temperature-resistant silicone powder is 70%~80%, and the mass ratio of the fluorine-containing processing aid PPA to the high-temperature-resistant silicone powder is 1:0.5~1. The percentages here are mass percentages.

[0018] Further, the antioxidant is a mixed compound antioxidant of a primary antioxidant and an auxiliary antioxidant; the primary antioxidant is one of antioxidant 1010, antioxidant 1098 and antioxidant 1790, the auxiliary antioxidant is one of antioxidant DSTP, antioxidant DLTP and antioxidant 168; the compound ratio of the primary antioxidant to the auxiliary antioxidant is 2-4:1. Preferably, 3:1.

[0019] Further, the application also discloses a preparation method of the high-flexibility fluoroplastic.

[0020] Step one, preparation of the flexible masterbatch

[0021] The raw materials of the flexible masterbatch include the following components in parts by weight:

[0022] THV 50-70 parts;

[0023] fluororubber 50-30 parts;

[0024] vulcanizing agent 1-1.5 parts;

[0025] accelerator 0.4-0.6 parts;

[0026] Firstly, the pre-mixed rubber is granulated, the fluororubber is put into the plasticator to be plasticized, the vulcanizing agent and the accelerator are added after 3-5 minutes, the plasticization is continued for 5-7 minutes, then the pre-mixed rubber particles are obtained by the single-screw extruder, and the setting temperature of the plasticator and the single-screw extruder is 80-90 DEG C, so that the extrusion is smooth while the rubber is prevented from being vulcanized in advance;

[0027] Then, the THV and the pre-mixed rubber particles are uniformly mixed and put into the twin-screw extruder, and the preparation of the flexible masterbatch is completed through the dynamic vulcanization process; wherein the length-diameter ratio of the twin-screw extruder is 36:1-40:1, the temperature setting is 150-185 DEG C, the rotating speed range is 50-150 rpm, and the material residence time is controlled to be 2.5-4 minutes;

[0028] Step two, preparation of the high-flexibility fluoroplastic

[0029] The fluoroplastic and the flexible masterbatch are put into the high-speed mixer and uniformly mixed at a rotating speed of 300-500 rpm; then the rotating speed is reduced to 200-300 rpm, the lubricant and the antioxidant are added while stirring; then the rotating speed is increased to 500-800 rpm, and the mixture is discharged after mixing for 3-5 minutes;

[0030] The mixed material is put into the twin-screw extruder, and the high-flexibility fluoroplastic is prepared through melt blending; the temperature setting of the twin-screw extruder is 180-360 DEG C, and the rotating speed range is 50-150 rpm.

[0031] Further, the THV is a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and the melt mass flow rate is 10-25 g / 10 min under the test condition of 297 DEG C and 5 kg.

[0032] Further, the fluororubber is any one of fluororubber 26 with bromine or iodine vulcanization site (CSM), fluororubber 246, tetrafluoroethylene-propylene rubber, perfluoroether rubber, preferably fluororubber 246 with bromine or iodine vulcanization site (CSM) or tetrafluoroethylene-propylene rubber, and the Mooney viscosity is 40-65 under the test condition of ML(1+10) and 121 DEG C.

[0033] Further, the vulcanizing agent is any one of triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPTMA) and trimethylolpropane trimethacrylate (TMPTA), preferably TAIC.

[0034] Further, the accelerator is any one of dicumyl peroxide (DCP) or 2,5-dimethyl-2,5-di-tert-butylperoxyhexane (AD), preferably AD.

[0035] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or the like are open-ended, that is, meaning "including but not limited to".

[0036] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or the like are open-ended, that is, meaning "including but not limited to".

[0037] The working principle and advantages of the present application are as follows:

[0038] The present application provides a kind of high flexible fluoroplastic and preparation method thereof, to solve the technical problems of the prior art such as polyvinylidene fluoride (PVDF), polytrifluorochloroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE) and ethylene-trifluorochloroethylene copolymer (ECTFE) high strength, insufficient flexible fluoroplastic material bending difficulty, difficult to adapt to deformation requirements, to significantly broaden its application scenarios.

[0039] Compared with the prior art, the technical effects of the present application mainly reflect in the following aspects:

[0040] 1. Significantly improve material flexibility: By using a dynamic vulcanization process to prepare flexible masterbatch and introducing it into the fluoroplastic matrix, the flexibility and bending properties of the material can be significantly improved, giving the originally rigid fluoroplastics excellent ability to adapt to deformation.

[0041] 2. Achieve efficient and uniform dispersion: The terpolymer (THV) of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride is selected as the carrier. It has similar structure and good compatibility with a variety of fluoroplastics. It can fully crosslink and uniformly disperse the fluororubber containing vulcanization sites during dynamic vulcanization, avoiding agglomeration or uneven dispersion, and providing a structural basis for performance improvement.

[0042] 3. Simplified process and improved efficiency: The use of a peroxide vulcanization system enables one-time full cross-linking of fluororubber during dynamic vulcanization, eliminating the need for the two-stage vulcanization process in traditional processes, thus shortening the process flow and improving production efficiency.

[0043] 4. Enhanced crack suppression and energy dissipation: During the stress process, the cross-linked fluororubber uniformly dispersed in the system can effectively absorb and dissipate impact energy through its three-dimensional network structure, inhibiting the initiation and propagation of microcracks (crazing), thus macroscopically manifesting as a significant improvement in the material's flexibility, toughness and bending resistance.

[0044] 5. Expanding the scope of applications: While basically maintaining the excellent properties of fluoroplastics such as corrosion resistance, weather resistance, and insulation, this invention effectively solves the bottleneck of insufficient flexibility, making the material suitable for emerging applications that require repeated bending and high flexibility. Attached Figure Description

[0045] Appendix Figure 1 This is a schematic diagram of the preparation method according to an embodiment of the present invention. Detailed Implementation

[0046] The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the embodiments of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0047] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0048] Step 1: Preparation of Softening Masterbatch

[0049] First, the premixing glue is granulated, the fluororubber is put into the internal mixer for plasticizing, 3-5 minutes later, the vulcanizing agent and the accelerator are added, and the plasticizing is continued for about 5 minutes, then the premixing glue particles are obtained by single screw extruder. The setting temperature of the internal mixer and the single screw extruder needs to be strictly controlled between 80-90℃, to avoid the rubber from being vulcanized in advance while ensuring the smoothness of extrusion.

[0050] Then the THV is mixed with the premixing glue particles in proportion, and is put into the twin-screw extruder to complete the preparation of the softening master batch by dynamic vulcanization process. The length-diameter ratio of the extruder is 36:1-40:1, the temperature setting is 150-185℃, the speed range is 50-150rpm, and the material residence time is controlled in 2.5-4 minutes.

[0051] Step two, preparation of high flexible fluoroplastic

[0052] The fluoroplastic and the softening master batch are put into the high-speed mixer in proportion, mixed uniformly at 300rpm, then the speed is reduced to 200rpm, the lubricant and the antioxidant are added while stirring, and then the speed is increased to 500rpm, the mixture is discharged after mixing for 3 minutes. The mixed material is put into the twin-screw extruder to prepare the high flexible fluoroplastic by melt blending. The temperature setting of the extruder is 180-360℃, the speed range is 50-150rpm, and the above processing parameters can be adjusted within the specified range according to the type of fluoroplastic.

[0053] Specifically, the following tests on different component formulations of examples and comparative examples are carried out to illustrate the technical effects of the present case.

[0054] Example 1

[0055] THV 50 parts (melt mass flow rate 20 g / 10 min, test conditions 297℃, 5 kg), fluororubber with CSM vulcanization site 246 50 parts (Mooney viscosity 45, test conditions ML(1+10), 121℃), vulcanizing agent TAIC 1.5 parts, accelerator AD 0.6 parts, are weighed, and the softening master batch is prepared according to step one. Then PVDF 80 parts, the obtained softening master batch 20 parts, lubricant 0.5 parts (containing fluoropolymer processing aid and high temperature resistant silicone powder mixed in a mass ratio of 1:1), and compound antioxidant 0.4 parts (main antioxidant 1010 and auxiliary antioxidant 168 mixed in a mass ratio of 3:1) are weighed, and the high flexible fluoroplastic is prepared according to step two.

[0056] Example 2

[0057] THV 70 parts (melt mass flow rate 20 g / 10 min), fluorine rubber 246 with CSM 246 30 parts (Mooney viscosity 45), TAIC 1.0 part, accelerator AD 0.4 part, and the softening master batch is prepared according to step one. Then PVDF 80 parts, softening master batch 20 parts, lubricant 0.5 parts (containing fluoropolymer processing agent and silicone powder 1:1), antioxidant 0.4 parts (1098 and 168 mixed in a mass ratio of 3:1), and the high flexible fluoroplastic is prepared according to step two.

[0058] Example 3

[0059] THV 50 parts (melt mass flow rate 20 g / 10 min), fluorine rubber 246 with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts, and the softening master batch is prepared according to step one. Then PVDF 50 parts, softening master batch 50 parts, lubricant 0.3 parts (containing fluoropolymer processing agent and silicone powder 1:1), antioxidant 0.4 parts (1010 and 168 mixed in a mass ratio of 3:1), and the high flexible fluoroplastic is prepared according to step two.

[0060] Example 4

[0061] THV 50 parts (melt mass flow rate 20 g / 10 min), fluorine rubber 246 with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts, and the softening master batch is prepared according to step one. Then PVDF 50 parts, softening master batch 50 parts, lubricant 0.3 parts (containing fluoropolymer processing agent and silicone powder 1:1), antioxidant 0.4 parts (1010 and 168 mixed in a mass ratio of 3:1), and the high flexible fluoroplastic is prepared according to step two.

[0062] Example 5

[0063] THV 50 parts (melt mass flow rate 20 g / 10 min), fluorine rubber 246 with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts, and the softening master batch is prepared according to step one. Then PVDF 50 parts, softening master batch 50 parts, lubricant 0.3 parts (containing fluoropolymer processing agent and silicone powder 1:1), antioxidant 0.4 parts (1010 and 168 mixed in a mass ratio of 3:1), and the high flexible fluoroplastic is prepared according to step two.

[0064] Example 6

[0065] THV 50 parts (melt mass flow rate 15 g / 10 min), fluorine rubber with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts were weighed out, and a softening masterbatch was prepared according to Step One. ECTFE 70 parts, the softening masterbatch 30 parts, lubricant 0.5 parts (containing fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1790 and DSTP mixed in a mass ratio of 3:1) were weighed out, and a high-flexibility fluoroplastic was prepared according to Step Two.

[0066] Example 7

[0067] THV 50 parts (melt mass flow rate 15 g / 10 min), fluorine rubber with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts were weighed out, and a softening masterbatch was prepared according to Step One. ECTFE 70 parts, the softening masterbatch 30 parts, lubricant 0.5 parts (containing fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1790 and DSTP mixed in a mass ratio of 3:1) were weighed out, and a high-flexibility fluoroplastic was prepared according to Step Two.

[0068] Comparative Example 1

[0069] THV 50 parts (melt mass flow rate 20 g / 10 min), fluorine rubber with CSM 246 50 parts (Mooney viscosity 45) were weighed out, and no vulcanizing agent and accelerator was added, and a softening masterbatch was directly prepared by a twin-screw extruder. PVDF 80 parts, the masterbatch 20 parts, lubricant 0.5 parts (containing fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1010 and 168 mixed in a mass ratio of 3:1) were weighed out, and a sample was prepared according to Step Two.

[0070] Comparative Example 2

[0071] THV 50 parts (melt mass flow rate 20 g / 10 min), ordinary fluorine rubber without CSM 246 50 parts (Mooney viscosity 50), TAIC 1.5 parts, accelerator AD 0.6 parts were weighed out, and a softening masterbatch was prepared according to Step One. PVDF 50 parts, the masterbatch 50 parts, lubricant 0.3 parts (containing fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1098 and 168 mixed in a mass ratio of 3:1) were weighed out, and a sample was prepared according to Step Two.

[0072] Comparative Example 3

[0073] Take PCTFE 70 parts, THV 30 parts (melt mass flow rate 15 g / 10 min), lubricant 0.5 parts (fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1790 and DSTP mixed in a mass ratio of 3:1), according to step two to prepare the sample.

[0074] Comparative Example 4

[0075] Take fluorine rubber with CSM 246 50 parts (Mooney viscosity 45), TAIC 1.5 parts, accelerator AD 0.6 parts, according to step one to prepare the premix rubber particles. Take ETFE 70 parts, the premix rubber particles 30 parts, lubricant 0.5 parts (fluoropolymer processing aid and silicone powder 1:1), antioxidant 0.4 parts (1790 and DSTP mixed in a mass ratio of 3:1), according to step two to prepare the sample.

[0076] The flexibility of the material can be intuitively reflected by the bending modulus, tensile elongation at break and surface hardness. Examples 1-7 and Comparative Examples 1-4 were hot-pressed into shape, and the tensile properties, bending properties and surface hardness of the samples were tested according to the test methods specified in GB / T 1040.2, GB / T 9341 and GB / T 2411. The test results are as follows:

[0077] Table 1 Performance data

[0078]

[0079] As can be seen from Examples 1 and 2 in Table 1, the higher the content of fluorine rubber in the softening masterbatch, the lower the bending modulus of the obtained sample, the higher the elongation at break, and the better the flexibility. The comparison of Example 1 with Examples 3 and 4 shows that when the amount of softening masterbatch increases from 30% to 50%, the bending modulus decreases by nearly 30%, the elongation at break increases, the surface hardness significantly decreases, and the flexibility greatly improves.

[0080] Compared with Example 1, the bending modulus of Comparative Example 1 is lower, but the mechanical properties are poor. The reason is that no vulcanizing agent is added in Comparative Example 1, and the fluororubber cannot achieve dynamic crosslinking, which is equivalent to melt blending the fluororubber raw rubber with THV and fluoroplastic, resulting in that the material cannot maintain stable performance. By comparing Comparative Example 3 with Comparative Example 2, it can be seen that the fluororubber used in Comparative Example 2 has no vulcanization site, and although it can achieve partial dynamic crosslinking under the action of the vulcanizing agent, the crosslinking degree is insufficient, the bending modulus is low, the overall mechanical properties decrease too much, and it also cannot maintain stability. The comparison of Example 5 and Example 6 with Comparative Example 3 and Comparative Example 4 further shows that the addition of THV alone has limited effect on the flexibility of fluoroplastic, and the material still shows great rigidity; and without the introduction of THV, the dynamic crosslinking of fluororubber in the fluoroplastic matrix only, the overall mechanical properties of the sample are poor, and defects such as low surface smoothness, easy scorching of fluororubber, yellowing of sample, etc. are observed in processing.

[0081] In summary, the flexible master batch prepared by the present application can significantly improve the flexibility of high-rigidity fluoroplastics such as PVDF, PCTFE, ETFE and ECTFE. The high-flexibility fluoroplastics obtained not only have excellent bending flexibility, but also have good mechanical properties, thereby being suitable for more widely used application scenarios.

[0082] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A highly flexible fluoroplastic characterized by: The raw materials include the following components in parts by weight: Fluoroplastic 80~50 parts; Flexible masterbatch 20~50 parts; Lubricant 0.2~1.0 parts; Antioxidant 0.1~0.5 parts.

2. The highly flexible fluoroplastic of claim 1, wherein: The fluoroplastic is one or more of polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, polyperfluoroalkyl alkoxy resin.

3. The highly flexible fluoroplastic of claim 1, wherein: The lubricant is a mixture of one or more of zinc stearate, calcium stearate, polytetrafluoroethylene powder, fluorine-containing processing aid PPA, ethylene bis-stearamide, and high-temperature-resistant silicone powder.

4. The highly flexible fluoroplastic of claim 3, wherein: The lubricant is a mixture of one or more of fluorine-containing processing aid PPA, polytetrafluoroethylene powder, ethylene bis-stearamide, and high-temperature-resistant silicone powder.

5. The highly flexible fluoroplastic of claim 4, wherein: The lubricant is a mixture of fluorine-containing processing aid PPA and high-temperature-resistant silicone powder; wherein the effective ingredient content of the fluorine-containing processing aid PPA is ≥95%, the silicone content of the high-temperature-resistant silicone powder is 70%~80%, and the mass ratio of the fluorine-containing processing aid PPA to the high-temperature-resistant silicone powder is 1:0.5~1.

6. The highly flexible fluoroplastic of claim 1, wherein: The antioxidant is a mixed compound antioxidant of a main antioxidant and an auxiliary antioxidant; wherein the main antioxidant is one of antioxidant 1010, antioxidant 1098, and antioxidant 1790, and the auxiliary antioxidant is one of antioxidant DSTP, antioxidant DLTP, and antioxidant 168; the compound ratio of the main antioxidant to the auxiliary antioxidant is 2~4:

1.

7. A method of making a highly flexible fluoroplastic characterized by: A method for preparing the high-flexibility fluoroplastic of any one of claims 1~6, the method comprising: Step one, preparation of flexible masterbatch The raw materials of the flexible masterbatch include the following components in parts by weight: THV 50~70 parts; Fluorine rubber 50~30 parts; Vulcanizing agent 1~1.5 parts; Accelerator 0.4~0.6 parts; First, the pre-mixed rubber is granulated, the fluorine rubber is put into the plasticator to plasticize, the vulcanizing agent and the accelerator are added after 3~5 minutes, the plasticization is continued for 5~7 minutes, and then the pre-mixed rubber particles are obtained by single screw extruder; the setting temperature of the plasticator and the single screw extruder is 80~90℃, which avoids premature vulcanization of the rubber while ensuring smooth extrusion; Then, the THV and the pre-mixed rubber particles are mixed uniformly and put into the twin-screw extruder to complete the preparation of the flexible masterbatch by dynamic vulcanization process; wherein the length-diameter ratio of the twin-screw extruder is 36:1~40:1, the temperature setting is 150~185℃, the rotation speed range is 50~150rpm, and the control material residence time is 2.5~4 minutes; Step two, preparation of high-flexibility fluoroplastic The fluoroplastic and the flexible masterbatch are put into the high-speed mixer and mixed uniformly at a rotation speed of 300~500rpm; then the rotation speed is reduced to 200~300rpm, the lubricant and the antioxidant are added while stirring; then the rotation speed is increased to 500~800rpm, and the mixture is discharged after mixing for 3~5 minutes; The mixed material is put into the twin-screw extruder to prepare the high-flexibility fluoroplastic by melt blending; the temperature setting of the twin-screw extruder is 180~360℃, and the rotation speed range is 50~150rpm.

8. The method of claim 7, wherein the fluoroplastic is a high flexibility fluoroplastic. The THV is a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and the melt mass flow rate is 10-25 g / 10 min, and the test conditions are 297 DEG C, 5 kg.

9. The method of claim 7, wherein the fluoroplastic is a high flexibility fluoroplastic. The fluorine rubber is any one of fluorine rubber 26 with bromine or iodine vulcanization site, fluorine rubber 246, tetrafluoro rubber, perfluoroether rubber, and the Mooney viscosity is 40-65, and the test conditions are ML (1+10), 121 DEG C.

10. The method of claim 7, wherein the fluoroplastic is a high flexibility fluoroplastic. The vulcanizing agent is any one of triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate.

11. The method of claim 7, wherein the fluoroplastic is a high flexibility fluoroplastic. The accelerator is any one of dicumyl peroxide or 2,5-dimethyl-2,5-di-tert-butyl peroxide.

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