PTFE sealing gasket and preparation method thereof

Abstract

The present invention belongs to the technical field of PTFE sealing gaskets, and specifically relates to a PTFE sealing gasket and a preparation method thereof. The PTFE sealing gasket described in the present invention is composed of the following raw materials: polytetrafluoroethylene, hexafluorobisphenol A type polyaryletherketone, methylphenyl silicone resin emulsion, polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber, and dodecyldimethylamine oxide modified graphene oxide. The PTFE sealing gasket described in the present invention adds hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion to polytetrafluoroethylene to ensure the mechanical properties and high temperature resistance of the prepared PTFE sealing gasket. Polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyldimethylamine oxide modified graphene oxide are added thereto, and the three act synergistically to improve the corrosion resistance, resilience and sealing performance of the prepared PTFE sealing gasket.

Description

Technical Field

[0001] The invention belongs to the technical field of PTFE sealing gaskets, and specifically relates to a PTFE sealing gasket and a preparation method thereof. Background Art

[0002] Gaskets have a sealing effect in industrial production. Sealing gaskets are made of metal or non-metal plates through cutting, stamping and cutting processes. They are used to seal pipes and parts of equipment and machines. They are divided into metal and non-metallic gaskets. Metal sealing gaskets include copper, iron and stainless steel gaskets; non-metallic sealing gaskets include rubber, asbestos, paper gaskets and polytetrafluoroethylene gaskets.

[0003] Bolted flange gasket sealing structures are often used in machinery, transportation, petrochemical, nuclear energy and other industries. Polytetrafluoroethylene is widely used as sealing material and filling material. Its main features are easy disassembly, high strength and good sealing performance. The gasket deforms under the action of the bolt preload and forms an initial sealing surface with the flange. Under the action of the medium pressure, the preload is reduced and the polytetrafluoroethylene gasket rebounds. When the maximum contact stress on the gasket is greater than the medium pressure, a good seal can be achieved, otherwise the seal fails.

[0004] With the rapid development of the domestic economy, various mechanical instruments use hydraulics and pneumatics to achieve power transmission, and the use environment they face is becoming more and more severe. For example, in aerospace, they need to face high temperature environments, and mechanical equipment in chemical environments need to face acidic and alkaline environments. This places increasing demands on sealing technology. In a high temperature environment, the compression modulus of polytetrafluoroethylene gaskets will be significantly reduced, the rebound modulus will be significantly increased, and the plastic strain of the gasket will be significantly increased. Moreover, as the load action time increases, the creep strain of the gasket will increase rapidly, the gasket stress will decrease, and the gasket's resilience will also decrease. And because polytetrafluoroethylene material has a symmetrical molecular structure, its crystals are easily peeled off, resulting in a large linear expansion coefficient and poor creep relaxation resistance, which limits the application of PTFE gaskets under high temperature and acid-base corrosion conditions. Therefore, it is necessary to explore a new type of PTFE sealing gasket and its preparation method. Summary of the invention

[0005] The purpose of the present invention is to provide a PTFE sealing gasket. The PTFE sealing gasket has a low creep relaxation rate at a high temperature of 200° C. and has corrosion resistance. The present invention also provides a preparation method thereof.

[0006] The PTFE sealing gasket of the present invention is composed of the following raw materials in percentage by mass: 65-68% of polytetrafluoroethylene, 12-15% of hexafluorobisphenol A type polyaryletherketone, 1.0-1.5% of methylphenyl silicone resin emulsion, 3.7-4.2% of polybenzothiazole fiber, 3.8-5.8% of polyisophthalamide-m-phenylenediamine fiber, and 9-11% of dodecyldimethylamine oxide-modified graphene oxide; wherein the preparation method of dodecyldimethylamine oxide-modified graphene oxide is as follows: graphene oxide and dodecyldimethylamine oxide are added to ethanol and ultrasonically treated for 2.3-2.5 hours, and then centrifuged, washed, and vacuum dried to prepare dodecyldimethylamine oxide-modified graphene oxide.

[0007] Among them: the manufacturer of methylphenyl silicone resin emulsion is Shanghai Koraman Reagent Co., Ltd.

[0008] The mass ratio of graphene oxide to dodecyldimethylamine oxide is 1:3.5-3.7.

[0009] The mass ratio of dodecyl dimethyl amine oxide to ethanol is 1:3.5-4.

[0010] The centrifugal speed is 6000r / min, and the washing is done by washing with deionized water 3-4 times.

[0011] The vacuum drying temperature is 135-140°C and the drying time is 3h.

[0012] The preparation method of the hexafluorobisphenol A type polyaryletherketone is as follows: hexafluorobisphenol A and 4,4'-difluorobenzophenone are placed in a reaction container, N-methylpyrrolidone is added, anhydrous potassium carbonate is added after heating and melting, the temperature is raised to 163-165° C. with stirring for reaction for 1.5 hours, the temperature is further raised to 205-207° C. for polymerization reaction for 1 hour, after the reaction is completed, the reaction mixture is poured into deionized water while hot for precipitation, and then washed with deionized water at 100° C. for 6-8 times, and finally vacuum dried at 85-87° C. for 12 hours to prepare the hexafluorobisphenol A type polyaryletherketone.

[0013] Wherein: the molar ratio of hexafluorobisphenol A to 4,4'-difluorobenzophenone is 1:1.

[0014] The molar ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1:1.1.

[0015] The total mass of hexafluorobisphenol A and 4,4'-difluorobenzophenone accounts for 20-22% of the total mass of hexafluorobisphenol A, 4,4'-difluorobenzophenone and N-methylpyrrolidone.

[0016] The reaction mixture is poured into deionized water while hot for precipitation, and the volume of the deionized water is 12-15 times the volume of the reaction mixture.

[0017] The PTFE sealing gasket of the present invention is based on polytetrafluoroethylene, hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion, and uses polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyldimethylamine oxide modified graphene oxide as fillers. Among them, hexafluorobisphenol A type polyaryletherketone itself has excellent chemical stability, mechanical properties and long-lasting fatigue resistance. The introduction of imide groups and F atoms into polyaryletherketone further improves its heat resistance and hydrophobicity. Hexafluorobisphenol A type polyaryletherketone is used to prepare PTFE gaskets, which ensures the mechanical strength of the prepared PTFE gaskets and enables the prepared PTFE gaskets to be used for a long time in an environment of >200°C. In addition, hexafluorobisphenol A type polyaryletherketone plays a role of heterogeneous nucleation in the PTFE sintering process, improves the crystallinity of PTFE materials, and at the same time, the molecular chain of hexafluorobisphenol A type polyaryletherketone and the molecular chain of PTFE are intertwined, avoiding large-area slip of PTFE lattice, so the creep resistance of the prepared gasket is improved. The addition of methylphenyl silicone resin emulsion can improve the compatibility between the raw materials for preparing polytetrafluoroethylene gaskets, and further improve the high temperature resistance of the prepared PTFE gaskets. The reason why polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyl dimethylamine oxide modified graphene oxide are added as fillers is to utilize the synergistic effect between the three to improve the corrosion resistance, sealing performance and resilience of the prepared polytetrafluoroethylene gasket. The lamellar structure of graphene oxide enables it to extend the invasion path of corrosion factors and has a physical barrier effect, but it is easy to agglomerate, so the graphene oxide is modified. There are a large number of oxygen-containing functional groups in graphene oxide, which can provide active sites for hydrophobic groups, and dodecyl dimethylamine oxide can provide hydrophobic alkyl chains. Therefore, after being modified with dodecyl dimethylamine oxide, graphene oxide has excellent corrosion resistance and hydrophobic properties. The main molecular chain of polybenzothiazole fiber contains benzimidazole repeating units and aromatic rings with a ladder structure, which makes it stable in heat shrinkage at high temperatures; polyisophthalamide fiber is highly oriented in the axial direction due to the molecular chain of isophthalamide, and hydrogen bonds can be formed between the molecular chains, so it has dimensional stability. In addition, polybenzothiazole fiber and polyisophthalamide fiber have good strength and rigidity. When the gasket is subjected to vertical force, the fiber filler distributed in the matrix can effectively prevent the slip of the lattice, play a rigid support role in the matrix, can effectively transfer the load, and prevent the gasket from deformation, cracks and other product defects. Therefore, when the polybenzothiazole fiber and the poly(m-phenylene isophthalamide) fiber are compounded and used, the PTFE gasket has good resilience and sealing performance when elastic deformation occurs.

[0018] The preparation method of the PTFE sealing gasket of the present invention comprises the following steps:

[0019] (1) Preparation of dodecyldimethylamine oxide modified graphene oxide;

[0020] (2) Preparation of hexafluorobisphenol A type polyaryletherketone;

[0021] (3) adding polytetrafluoroethylene into an air flow mixer, then adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion and mixing for 8-10 minutes, and finally adding polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyl dimethylamine oxide modified graphene oxide and mixing for 3-5 minutes to prepare a mixture;

[0022] (4) The mixture is poured into a mold and pressed into shape, and then the temperature is raised to 360-365°C and sintered for 5-5.5 hours. After sintering, the temperature is first lowered to 320°C at a rate of 5°C / h, and then lowered to room temperature at a rate of 12.8°C / h to prepare a PTFE sealing gasket.

[0023] in:

[0024] The mixing temperature in step (3) is 18-20°C.

[0025] The pressing pressure in step (4) is 45 MPa, the pressing time is 20-23 min, and the pressing temperature is room temperature.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The PTFE sealing gasket of the present invention is prepared by adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion to polytetrafluoroethylene to ensure the mechanical properties and high temperature resistance of the prepared PTFE sealing gasket. Polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyldimethylamine oxide modified graphene oxide are added thereto, and the three act synergistically to improve the corrosion resistance, resilience and sealing performance of the prepared PTFE sealing gasket.

[0028] (2) The preparation method of the PTFE sealing gasket described in the present invention has readily available raw materials, easy-to-control process parameters, and the prepared PTFE sealing gasket has stable performance. DETAILED DESCRIPTION

[0029] The present invention is further described below with reference to the embodiments.

[0030] Example 1

[0031] The PTFE sealing gasket described in Example 1 is composed of the following raw materials, measured in mass percentage: 67% polytetrafluoroethylene, 13% hexafluorobisphenol A type polyaryletherketone, 1.2% methylphenyl silicone resin emulsion, 4.0% polybenzothiazole fiber, 4.8% polyisophthalamide m-phenylenediamine fiber, and 10% dodecyldimethylamine oxide-modified graphene oxide; wherein the preparation method of dodecyldimethylamine oxide-modified graphene oxide is: adding graphene oxide and dodecyldimethylamine oxide to ethanol and ultrasonically treating them for 2.4 hours, and then centrifuging, washing, and vacuum drying to prepare dodecyldimethylamine oxide-modified graphene oxide.

[0032] Among them: the manufacturer of methylphenyl silicone resin emulsion is Shanghai Koraman Reagent Co., Ltd.

[0033] The mass ratio of graphene oxide to dodecyldimethylamine oxide is 1:3.6.

[0034] The mass ratio of dodecyl dimethyl amine oxide to ethanol is 1:3.7.

[0035] The centrifugal speed was 6000 r / min, and the washing was performed 4 times with deionized water.

[0036] The vacuum drying temperature was 137°C and the drying time was 3 h.

[0037] The preparation method of the hexafluorobisphenol A type polyaryletherketone is as follows: hexafluorobisphenol A and 4,4'-difluorobenzophenone are placed in a reaction container, N-methylpyrrolidone is added, anhydrous potassium carbonate is added after heating and melting, the mixture is stirred and heated to 164°C for reaction for 1.5 hours, the mixture is further heated to 206°C for polymerization reaction for 1 hour, after the reaction is completed, the reaction mixture is poured into deionized water while hot for precipitation, and then washed with deionized water at 100°C for 7 times, and finally vacuum dried at 86°C for 12 hours to prepare the hexafluorobisphenol A type polyaryletherketone.

[0038] Wherein: the molar ratio of hexafluorobisphenol A to 4,4'-difluorobenzophenone is 1:1.

[0039] The molar ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1:1.1.

[0040] The total mass of hexafluorobisphenol A and 4,4'-difluorobenzophenone accounts for 21% of the total mass of hexafluorobisphenol A, 4,4'-difluorobenzophenone and N-methylpyrrolidone.

[0041] The reaction mixture is poured into deionized water while hot for precipitation, and the volume of the deionized water is 14 times the volume of the reaction mixture.

[0042] The preparation method of the PTFE sealing gasket described in this embodiment 1 consists of the following steps:

[0043] (1) Preparation of dodecyldimethylamine oxide modified graphene oxide;

[0044] (2) Preparation of hexafluorobisphenol A type polyaryletherketone;

[0045] (3) adding polytetrafluoroethylene into an air flow mixer, then adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion and mixing for 9 minutes, and finally adding polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyldimethylamine oxide modified graphene oxide and mixing for 4 minutes to prepare a mixture;

[0046] (4) The mixture is poured into a mold and pressed into shape, and then the temperature is raised to 363°C and sintered for 5.3 hours. After sintering, the temperature is first lowered to 320°C at a rate of 5°C / h, and then lowered to room temperature at a rate of 12.8°C / h to prepare a PTFE sealing gasket.

[0047] in:

[0048] The mixing temperature in step (3) is 19°C.

[0049] The pressing pressure in step (4) is 45 MPa, the pressing time is 21 min, and the pressing temperature is room temperature.

[0050] Example 2

[0051] The PTFE sealing gasket described in Example 2 is composed of the following raw materials, measured in mass percentage: 68% polytetrafluoroethylene, 12% hexafluorobisphenol A type polyaryletherketone, 1.0% methylphenyl silicone resin emulsion, 4.2% polybenzothiazole fiber, 5.8% polyisophthalamide m-phenylenediamine fiber, and 9% dodecyldimethylamine oxide-modified graphene oxide; wherein the preparation method of dodecyldimethylamine oxide-modified graphene oxide is: adding graphene oxide and dodecyldimethylamine oxide to ethanol and ultrasonically treating them for 2.3 hours, and then centrifuging, washing, and vacuum drying to prepare dodecyldimethylamine oxide-modified graphene oxide.

[0052] Among them: the manufacturer of methylphenyl silicone resin emulsion is Shanghai Koraman Reagent Co., Ltd.

[0053] The mass ratio of graphene oxide to dodecyldimethylamine oxide is 1:3.5.

[0054] The mass ratio of dodecyl dimethyl amine oxide to ethanol is 1:3.5.

[0055] The centrifugal speed was 6000 r / min, and the washing was performed 3 times with deionized water.

[0056] The vacuum drying temperature was 135°C and the drying time was 3 h.

[0057] The preparation method of the hexafluorobisphenol A type polyaryletherketone is as follows: hexafluorobisphenol A and 4,4'-difluorobenzophenone are placed in a reaction container, N-methylpyrrolidone is added, anhydrous potassium carbonate is added after heating and melting, the mixture is stirred and heated to 163°C for reaction for 1.5 hours, the mixture is further heated to 205°C for polymerization reaction for 1 hour, after the reaction is completed, the reaction mixture is poured into deionized water while hot for precipitation, and then washed with deionized water at 100°C for 6 times, and finally vacuum dried at 85°C for 12 hours to prepare the hexafluorobisphenol A type polyaryletherketone.

[0058] Wherein: the molar ratio of hexafluorobisphenol A to 4,4'-difluorobenzophenone is 1:1.

[0059] The molar ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1:1.1.

[0060] The total mass of hexafluorobisphenol A and 4,4'-difluorobenzophenone accounts for 22% of the total mass of hexafluorobisphenol A, 4,4'-difluorobenzophenone and N-methylpyrrolidone.

[0061] The reaction mixture is poured into deionized water while hot for precipitation, and the volume of the deionized water is 12 times the volume of the reaction mixture.

[0062] The preparation method of the PTFE sealing gasket described in this embodiment 2 consists of the following steps:

[0063] (1) Preparation of dodecyldimethylamine oxide modified graphene oxide;

[0064] (2) Preparation of hexafluorobisphenol A type polyaryletherketone;

[0065] (3) adding polytetrafluoroethylene into an air flow mixer, then adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion and mixing for 8 minutes, and finally adding polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyl dimethylamine oxide modified graphene oxide and mixing for 5 minutes to prepare a mixture;

[0066] (4) The mixture is poured into a mold and pressed into shape, and then the temperature is raised to 360°C and sintered for 5.5 hours. After sintering, the temperature is first lowered to 320°C at a rate of 5°C / h, and then lowered to room temperature at a rate of 12.8°C / h to prepare a PTFE sealing gasket.

[0067] in:

[0068] The mixing temperature in step (3) is 18°C.

[0069] The pressing pressure in step (4) is 45 MPa, the pressing time is 20 min, and the pressing temperature is room temperature.

[0070] Example 3

[0071] The PTFE sealing gasket described in Example 3 is composed of the following raw materials, measured in mass percentage: 65% polytetrafluoroethylene, 15% hexafluorobisphenol A type polyaryletherketone, 1.5% methylphenyl silicone resin emulsion, 3.7% polybenzothiazole fiber, 3.8% polyisophthalamide m-phenylenediamine fiber, and 11% dodecyldimethylamine oxide-modified graphene oxide; wherein the preparation method of dodecyldimethylamine oxide-modified graphene oxide is: adding graphene oxide and dodecyldimethylamine oxide to ethanol and ultrasonically treating them for 2.5 hours, and then centrifuging, washing, and vacuum drying to prepare dodecyldimethylamine oxide-modified graphene oxide.

[0072] Among them: the manufacturer of methylphenyl silicone resin emulsion is Shanghai Koraman Reagent Co., Ltd.

[0073] The mass ratio of graphene oxide to dodecyldimethylamine oxide is 1:3.7.

[0074] The mass ratio of dodecyl dimethyl amine oxide to ethanol is 1:4.

[0075] The centrifugal speed was 6000 r / min, and the washing was performed 4 times with deionized water.

[0076] The vacuum drying temperature is 140°C and the drying time is 3 h.

[0077] The preparation method of the hexafluorobisphenol A type polyaryletherketone is as follows: hexafluorobisphenol A and 4,4'-difluorobenzophenone are placed in a reaction container, N-methylpyrrolidone is added, anhydrous potassium carbonate is added after heating and melting, the mixture is stirred and heated to 165°C for reaction for 1.5 hours, the mixture is further heated to 207°C for polymerization reaction for 1 hour, after the reaction is completed, the reaction mixture is poured into deionized water while hot for precipitation, and then washed with deionized water at 100°C for 8 times, and finally vacuum dried at 87°C for 12 hours to prepare the hexafluorobisphenol A type polyaryletherketone.

[0078] Wherein: the molar ratio of hexafluorobisphenol A to 4,4'-difluorobenzophenone is 1:1.

[0079] The molar ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1:1.1.

[0080] The sum of the masses of hexafluorobisphenol A and 4,4'-difluorobenzophenone accounts for 20% of the sum of the masses of hexafluorobisphenol A, 4,4'-difluorobenzophenone and N-methylpyrrolidone.

[0081] The reaction mixture is poured into deionized water while hot for precipitation, and the volume of the deionized water is 15 times the volume of the reaction mixture.

[0082] The preparation method of the PTFE sealing gasket described in this embodiment 3 consists of the following steps:

[0083] (1) Preparation of dodecyldimethylamine oxide modified graphene oxide;

[0084] (2) Preparation of hexafluorobisphenol A type polyaryletherketone;

[0085] (3) adding polytetrafluoroethylene into an air flow mixer, then adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion and mixing for 10 minutes, and finally adding polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyldimethylamine oxide modified graphene oxide and mixing for 3 minutes to prepare a mixture;

[0086] (4) The mixture is poured into a mold and pressed into shape, and then the temperature is raised to 365°C and sintered for 5 hours. After sintering, the temperature is first lowered to 320°C at a rate of 5°C / h, and then lowered to room temperature at a rate of 12.8°C / h to prepare a PTFE sealing gasket.

[0087] in:

[0088] The mixing temperature in step (3) is 20°C.

[0089] The pressing pressure in step (4) is 45 MPa, the pressing time is 23 min, and the pressing temperature is room temperature.

[0090] Comparative Example 1

[0091] The preparation method of the PTFE sealing gasket described in this comparative example 1 is the same as that of Example 1, the only difference being that dodecyl dimethylamine oxide-modified graphene oxide is not added to the raw materials. The PTFE sealing gasket described in this comparative example 1 is composed of the following raw materials, by mass percentage: 77% polytetrafluoroethylene, 13% hexafluorobisphenol A type polyaryletherketone, 1.2% methylphenyl silicone resin emulsion, 4.0% polybenzothiazole fiber, and 4.8% polyisophthalamide fiber.

[0092] Comparative Example 2

[0093] The preparation method of the PTFE sealing gasket described in this comparative example 2 is the same as that of Example 1, the only difference being that polybenzothiazole fiber and polyisophthalamide fiber are not added to the raw materials. The PTFE sealing gasket described in this comparative example 2 is composed of the following raw materials by mass percentage: 75.8% polytetrafluoroethylene, 13% hexafluorobisphenol A type polyaryletherketone, 1.2% methylphenyl silicone resin emulsion, and 10% dodecyl dimethylamine oxide modified graphene oxide.

[0094] The PTFE sealing gaskets prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the tensile strength test was based on GB / T 20671.7-2006; the leakage rate test was based on GB / T 12385-2008 Pipe flange gasket sealing performance test method; the compression rate and rebound rate test were based on GB / T 12622-2008 Pipe flange gasket compression rate and rebound rate test method, and the test load was 35 MPa; the creep relaxation rate test was based on GB / T 20671.5-2020 Non-metallic gasket material classification system and test method, and the test temperature was 200°C; the acid resistance test was to immerse the PTFE sealing gasket in 5% sulfuric acid solution for 10 days and then test its tensile strength; the alkali resistance test was to immerse the PTFE sealing gasket in 5% sodium hydroxide solution for 10 days and then test its tensile strength; the results are shown in Table 1 below:

[0095] Table 1 PTFE sealing gasket performance test results

[0096]

Claims

1. A PTFE sealing gasket, characterized in that: The invention is composed of the following raw materials in percentage by mass: 65-68% polytetrafluoroethylene, 12-15% hexafluorobisphenol A type polyaryletherketone, 1.0-1.5% methylphenyl silicone resin emulsion, 3.7-4.2% polybenzothiazole fiber, 3.8-5.8% polyisophthalamide m-phenylenediamine fiber, and 9-11% dodecyldimethylamine oxide modified graphene oxide; wherein the preparation method of dodecyldimethylamine oxide modified graphene oxide is as follows: graphene oxide and dodecyldimethylamine oxide are added to ethanol and ultrasonically treated for 2.3-2.5 hours, and then centrifuged, washed, and vacuum dried to prepare dodecyldimethylamine oxide modified graphene oxide; The preparation method of the hexafluorobisphenol A type polyaryletherketone is as follows: hexafluorobisphenol A and 4,4'-difluorobenzophenone are placed in a reaction container, N-methylpyrrolidone is added, anhydrous potassium carbonate is added after heating and melting, the mixture is stirred and heated to 163-165° C. for reaction for 1.5 hours, the mixture is further heated to 205-207° C. for polymerization reaction for 1 hour, after the reaction is completed, the reaction mixture is poured into deionized water while hot for precipitation, and then washed with deionized water at 100° C. for 6-8 times, and finally vacuum dried at 85-87° C. for 12 hours to prepare the hexafluorobisphenol A type polyaryletherketone; in: The molar ratio of hexafluorobisphenol A to 4,4'-difluorobenzophenone is 1:1; The molar ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1:1.1; The sum of the mass of hexafluorobisphenol A and 4,4'-difluorobenzophenone accounts for 20-22% of the sum of the mass of hexafluorobisphenol A, 4,4'-difluorobenzophenone and N-methylpyrrolidone; The reaction mixture is poured into deionized water while hot for precipitation, and the volume of the deionized water is 12-15 times the volume of the reaction mixture.

2. The PTFE sealing gasket according to claim 1, characterized in that: The mass ratio of graphene oxide to dodecyldimethylamine oxide is 1:3.5-3.

7.

3. The PTFE sealing gasket according to claim 1, characterized in that: The mass ratio of dodecyl dimethyl amine oxide to ethanol is 1:3.5-4.

4. The PTFE sealing gasket according to claim 1, characterized in that: During the preparation of dodecyldimethylamine oxide-modified graphene oxide, the centrifugal speed is 6000 r / min, and the washing is performed 3-4 times with deionized water.

5. The PTFE sealing gasket according to claim 1, characterized in that: During the preparation of dodecyldimethylamine oxide-modified graphene oxide, the vacuum drying temperature is 135-140° C. and the drying time is 3 h.

6. A method for preparing the PTFE sealing gasket according to claim 1, characterized in that: It consists of the following steps: (1) Preparation of dodecyldimethylamine oxide modified graphene oxide; (2) Preparation of hexafluorobisphenol A type polyaryletherketone; (3) adding polytetrafluoroethylene into an air flow mixer, then adding hexafluorobisphenol A type polyaryletherketone and methylphenyl silicone resin emulsion and mixing for 8-10 minutes, and finally adding polybenzothiazole fiber, polyisophthalamide m-phenylenediamine fiber and dodecyl dimethylamine oxide modified graphene oxide and mixing for 3-5 minutes to prepare a mixture; (4) The mixture is poured into a mold and pressed into shape, and then the temperature is raised to 360-365°C and sintered for 5-5.5 hours. After sintering, the temperature is first lowered to 320°C at a rate of 5°C / h, and then lowered to room temperature at a rate of 12.8°C / h to prepare a PTFE sealing gasket.

7. The method for preparing a PTFE sealing gasket according to claim 6, characterized in that: The mixing temperature in step (3) is 18-20°C; The pressing pressure in step (4) is 45 MPa, the pressing time is 20-23 min, and the pressing temperature is room temperature.

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