Preparation method of perfluoroether rubber

Abstract

The invention relates to the technical field of preparation of perfluoroether rubber, in particular to a preparation method of perfluoroether rubber, which is characterized in that through a coherent'polymerization-internal mixing-open mixing-vulcanization 'process, the Mooney viscosity is obviously reduced to be less than or equal to 20 ML, the fluidity is improved by 2.5 times, weld marks are thoroughly eliminated, and the molding yield is more than or equal to 99.5%; low-temperature rapid vulcanization saves energy by 20%, the heat resistance grade is improved to 300 DEG C * 168 h compression set less than or equal to 10%, meanwhile, the service life of the mold is prolonged, waste products are reduced, the comprehensive cost is reduced by 15%, and the advantages of high flowability, high heat resistance, high yield and low cost are achieved. Therefore, the problems of high Mooney viscosity, poor flowability, obvious weld marks and insufficient heat resistance in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of perfluoroether rubber preparation technology, and in particular to a method for preparing perfluoroether rubber. Background Technology

[0002] Perfluoroelastomer (FFKM) rubber, due to its perfluoropolymer main chain structure, possesses excellent chemical resistance and high-temperature resistance, earning it the title of "king of sealing materials." However, the highly symmetrical perfluoropolymer segments result in extremely strong intermolecular interactions, leading to a Mooney viscosity in raw rubber typically exceeding 100 ml, resulting in extremely poor material flowability. During compression molding, the rubber compound must flow through complex channels, and its high viscosity makes it difficult for the melt front to converge, easily forming obvious weld lines, which become stress concentration sources, causing early cracking and leakage in sealed products, resulting in a persistently high defect rate (industry average ≥15%). Furthermore, the high viscosity forces processing companies to increase mold temperature and extend vulcanization time, increasing energy consumption by more than 20%, and placing extremely high demands on mold surface finish, further driving up costs.

[0003] Existing technologies mainly employ three methods to improve processability: ① Physically adding low molecular weight fluoroether oil as a plasticizer, but small molecules are prone to migration and volatilization at high temperatures, causing the seals to shrink in volume and undergo a sharp increase in permanent compression deformation when working at temperatures above 200 ℃ for extended periods; ② Introducing precipitated silica, which can slightly reduce Mooney, but due to its high surface hydroxyl content and poor compatibility with the perfluorinated matrix, it agglomerates severely, becoming a new stress concentration point and reducing tear strength by more than 30%; ③ Increasing the amount of vulcanizing agent to reduce crosslinking density, but this leads to a simultaneous deterioration in heat resistance and chemical resistance, failing to meet the requirements of high-end applications such as semiconductors and aerospace. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing perfluoroether rubber, which aims to solve the problems of high Mooney viscosity, poor flowability, obvious weld lines, and insufficient heat resistance in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for preparing perfluoroether rubber, comprising the following steps: Aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer and 0.01-0.1 wt% chain transfer agent are added to a high-pressure reactor and subjected to free radical emulsion polymerization at pH=3-4, 70-80℃ and 2.0-2.5 MPa to obtain fluorinated raw rubber; 100 parts by weight of fluorinated raw rubber were put into an internal mixer, and spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant and processing aid were added in sequence. The mixture was internally mixed at 60-80℃ and 40-60rpm for 5-10 minutes. The discharge temperature was ≤90℃ to obtain the rubber compound. After the rubber compound is milled 2-3 times with three rollers, a secondary vulcanization aid is added on an open rubber mixing mill. After passing through a thin mill 5-7 times, the rubber is sheeted to obtain a rubber sheet. The rubber sheet is vulcanized once under light on a flat vulcanizing machine, and then vulcanized a second time in an oven to obtain a low Mooney, high flow perfluoroether rubber.

[0006] The method described in the section "adding an aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer, and 0.01-0.1 wt% chain transfer agent to a high-pressure reactor, and carrying out free radical emulsion polymerization under conditions of pH=3-4, 70-80℃, and 2.0-2.5 MPa to obtain fluorinated raw rubber" includes the following steps: Add deionized water, ammonium perfluorooctanoate, and potassium dihydrogen phosphate to the high-pressure reactor. Adjust the pH to 3-4 with dilute hydrochloric acid and purge with nitrogen to remove oxygen until dissolved oxygen is ≤0.5ppm. The tetrafluoroethylene (40-60 wt%), perfluoromethyl vinyl ether (15-25 wt%), perfluorocyano vinyl ether (1-5 wt%), and carboxyl-terminated liquid fluoroether telomer (0.5-2 wt%) are sequentially pressed into the reactor. A single injection of 0.01-0.1 wt% 1-iodoperfluorobutane; Heat to 70-80℃, add potassium persulfate, and perform free radical emulsion polymerization at 2.0-2.5MPa; The mixed monomers are automatically replenished as the reaction consumes them, maintaining a constant pressure. When the conversion rate reaches 90-95%, the temperature is lowered, the pressure is released, and an aqueous solution of hydroquinone is added to terminate the process. The mixture is then coagulated, washed, and vacuum dried at 80°C to obtain 60-80 mL of Mooney fluorinated raw gum at 100°C (1+10).

[0007] Among them, in the "automatic replenishment of mixed monomers as the reaction consumes, maintaining constant pressure", the monomer metering accuracy is ±0.2%, and the pressure fluctuation during the constant pressure replenishment stage is ≤±0.05MPa.

[0008] The section on "adding 100 parts by weight of fluorinated raw rubber to an internal mixer, and sequentially adding spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant, and processing aid, and mixing at 60-80℃ and 40-60rpm for 5-10 minutes, with a discharge temperature ≤90℃ to obtain the rubber compound" includes the following steps: Add 100 parts of fluorinated raw rubber to a mixer and masticate at 60°C and 60 rpm for 2 minutes. Add 5-15 parts of modified spherical SiO2 with an average particle size of 0.2-0.8 μm and a sphericity ≥0.92, and mix at 80 rpm for 1.5 min; Add 0.5-3 parts of hollow glass microspheres and 1-5 parts of boron nitride nanosheets premix, and shear at 80℃ for 3 min; Add 0.3-2 parts of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 60 rpm for 1 min; Add 1-3 parts of microencapsulated peroxide vulcanizing agent, 0.1-1 parts of rare earth lubricant lanthanum stearate, and 0.2-1 parts of processing aid pentaerythritol tetrastearate. Mix at 50-60 rpm for 2 minutes. The discharge temperature is ≤90℃ to obtain the rubber compound.

[0009] The spherical SiO2 is pre-modified with KH-570+1H,1H,2H,2H-perfluorooctyltrimethoxysilane, with a grafting rate ≥6wt%; The true density of the hollow glass microspheres is 0.15-0.25 g / cm³. 3 The thickness of boron nitride nanosheets is ≤5nm, the premixed shear rate is 1500rpm, and the thermal conductivity of the adhesive after the thermally conductive skeleton is formed is ≥0.45W / (m·K). The microcapsule wall material is composed of polyvinyl alcohol, chitosan, and fluorosilicone resin in a ratio of 5:2:3, with a wall thickness of 1-3 μm, and completely ruptures within 3 minutes at 170°C.

[0010] The step of "grinding the rubber compound 2-3 times with three rollers, adding a secondary vulcanizing agent on an open mixing mill, passing it through a thin sheet 5-7 times, and then sheeting it to obtain a rubber sheet" includes the following steps: Pass the rubber compound through three rollers 2-3 times, with a roller gap of 0.5mm; With the roller temperature at 50℃, add 0.2-0.5 parts of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and pass through the roller 5-7 times. Adjust the roller gap to 2mm, lower the sheet by 2mm, wind up the release film, and cool to ≤30℃.

[0011] The step of "performing a first vulcanization of the rubber sheet under light on a flat vulcanizing machine, followed by a second vulcanization in an oven to obtain a low Mooney, high-flow perfluoroether rubber" includes the following steps: Preheat the mold to 170-180℃ and spray with rare earth-fluorosilicone release agent; A single vulcanization process is carried out under conditions of 10-15 MPa, 170-180℃, and 10-15 min. The temperature is increased to 200-220℃ and carried out for 2-4 hours for secondary vulcanization, followed by furnace cooling. Wiping with ethanol and standing at 23℃×50%RH for 24 hours yields a low Mooney and high flow perfluoroether rubber.

[0012] This invention discloses a method for preparing perfluoroether rubber. Through a continuous "polymerization-mixing-open milling-vulcanization" process, this invention significantly reduces Mooney viscosity to ≤20 ML, improves flowability by 2.5 times, completely eliminates weld lines, and achieves a molding yield of ≥99.5%. Low-temperature rapid vulcanization saves 20% energy, improves heat resistance to 300 ℃×168 h with compression set ≤10%, while extending mold life, reducing scrap, and lowering overall cost by 15%. It combines the advantages of high flowability, high heat resistance, high yield, and low cost. This solves the problems of high Mooney viscosity, poor flowability, obvious weld lines, and insufficient heat resistance in existing technologies. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a method for preparing perfluoroether rubber provided by the present invention.

[0015] Figure 2 The process involves adding an aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer, and 0.01-0.1 wt% chain transfer agent to a high-pressure reactor and carrying out free radical emulsion polymerization under conditions of pH=3-4, 70-80℃, and 2.0-2.5 MPa to obtain fluorinated raw rubber.

[0016] Figure 3 The process involves feeding 100 parts by weight of fluorinated raw rubber into an internal mixer, then sequentially adding spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant, and processing aids. The mixture is then internally mixed at 60-80℃ and 40-60rpm for 5-10 minutes, with a discharge temperature ≤90℃, to obtain the rubber compound.

[0017] Figure 4 The process involves grinding the rubber compound 2-3 times with three rollers, adding a secondary vulcanizing agent on an open rubber mixing mill, and then passing it through a thin mill 5-7 times before sheeting it to obtain a rubber sheet.

[0018] Figure 5The flowchart describes the process of vulcanizing a rubber sheet under light on a flat vulcanizing machine and then vulcanizing it a second time in an oven to obtain a low Mooney, high flow perfluoroether rubber. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] Please see Figures 1 to 5 This invention provides a method for preparing perfluoroether rubber, comprising the following steps: S1 involves adding an aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer, and 0.01-0.1 wt% chain transfer agent to a high-pressure reactor and carrying out free radical emulsion polymerization at pH=3-4, 70-80℃, and 2.0-2.5 MPa to obtain fluorinated raw rubber. S11 Add deionized water, ammonium perfluorooctanoate, and potassium dihydrogen phosphate to the high-pressure reactor, adjust the pH to 3-4 with dilute hydrochloric acid, and purge with nitrogen to remove oxygen until dissolved oxygen is ≤0.5ppm; Specifically, check the airtightness of the vessel (nitrogen pressure 0.5 MPa, pressure drop ≤ 0.01 MPa after 30 minutes). Perform vacuum-nitrogen purging three times, monitoring the oxygen content online to ≤ 0.5 ppm. Add 30 kg of deionized water, 50 g of ammonium perfluorooctanoate, and 2 g of potassium dihydrogen phosphate; start low-speed stirring at 200 rpm. Add dilute hydrochloric acid (1 mol / L) dropwise until pH = 3.2 ± 0.05 (Mettler Toledo online pH electrode, ± 0.01). KPI: dissolved oxygen ≤ 0.5 ppm; pH 3.2 ± 0.05.

[0021] S12 is sequentially added into the reactor in the following proportions: 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, and 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer. Specifically, the monomer storage tank is circulated with a -10℃ chiller to prevent TFE self-polymerization. A mass flow meter (BronkhorstCORI-FLOW, accuracy ±0.2%FS) sequentially injects: 12kg TFE → 4.5kg PMVE → 0.6kg PNVE → 0.3kg terminal carboxyl-terminated liquid fluoroether telomer. After each batch is injected, the pipeline is flushed with 20mL of deionized water to prevent monomer residue. KPI: Cumulative mass deviation ≤ ±0.2%.

[0022] S13 is injected with 0.01-0.1 wt% 1-iodoperfluorobutane in a single injection; Specifically, using a high-pressure plunger pump (HPLC316L pump head), inject 0.05wt% (total monomer amount) of 1-iodoperfluorobutane / 10mL of perfluorohexane into the bottom of the vessel within 30 seconds. Immediately close the injection valve and record the instantaneous pressure change (fluctuation should be ≤0.02MPa). KPI: Injection time ≤30s; pressure fluctuation ≤0.02MPa.

[0023] S14 is heated to 70-80℃, potassium persulfate is added, and free radical emulsion polymerization is carried out at 2.0-2.5MPa; Specifically, start the heat transfer oil circulation and raise the temperature at a rate of 1℃ / min to 75℃. When the temperature is ≥70℃, add 3g of potassium persulfate (5mL aqueous solution) at once and close the feed port. Start timing when the pressure rises to 2.3MPa; record the temperature-pressure curve using the DCS. KPI: T=75±0.5℃; P=2.3±0.05MPa.

[0024] S15 automatically replenishes mixed monomers as the reaction is consumed, maintaining constant pressure; The accuracy of single-unit metering is ±0.2%, and the pressure fluctuation during the constant pressure replenishment stage is ≤±0.05MPa.

[0025] Specifically, when the reaction consumption causes a pressure drop of 0.05 MPa, a TFE / PMVE = 75 / 25 mixture is automatically added to maintain a pressure of 2.3 ± 0.05 MPa. The cumulative mass is recorded every 5 minutes; when the total intake volume reaches 90% of the theoretical value, the replenishment valve is closed. KPIs: Pressure fluctuation ≤ ±0.05 MPa; Individual unit metering accuracy ±0.2%.

[0026] When the S16 conversion rate reaches 90-95%, the temperature is lowered, the pressure is released, and an aqueous solution of hydroquinone is added to terminate the process. After coagulation, washing, and vacuum drying at 80℃, 60-80 mL of Mooney fluorinated raw gum (1+10) at 100℃ is obtained.

[0027] Specifically, cool the material to 35℃ using cooling water (cooling rate ≥ 5℃ / min). Depressurize to 0.2MPa, add 50mL of 10wt% hydroquinone aqueous solution, and stir for 10min. Discharge → 0.8MPa coagulation tank → wash 3 times with 80℃ hot water → centrifuge to dehydrate → vacuum dry at 80℃ for 12h. Sample and measure Mooney viscosity (MV2000, 125℃, 1+10min). KPIs: Raw rubber Mooney viscosity 60-80mL; volatile matter ≤ 0.5%; conversion rate ≥ 92%.

[0028] S2. 100 parts by weight of fluorinated raw rubber are put into an internal mixer, and spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant and processing aid are added in sequence. The mixture is then internally mixed at 60-80℃ and 40-60rpm for 5-10min. The discharge temperature is ≤90℃ to obtain the rubber compound. S21: 100 parts of fluorinated raw rubber are put into an internal mixer and plasticized at 60°C and 60 rpm for 2 minutes. Specifically, preheat the internal mixer to 60℃ and set the rotor to 60 rpm. Add 100 parts of raw rubber, press the top bolt, and masticate for 2 minutes. KPIs: Rubber temperature ≤ 65℃; Torque drop plateau ≥ 10%.

[0029] Add 5-15 parts of modified spherical SiO2 to S22, with an average particle size of 0.2-0.8 μm and a sphericity ≥0.92, and mix at 80 rpm for 1.5 min; The spherical SiO2 is pre-modified with KH-570+1H,1H,2H,2H-perfluorooctyltrimethoxysilane for secondary surface modification, with a grafting rate ≥6wt%; Specifically, 10 parts of secondary modified SiO2 (0.5μm, sphericity 0.95) were added in two batches, 30 seconds apart. The mixing speed was increased to 80 rpm, and the mixture was kneaded for 1.5 min. The dispersion point was determined by an online torque-temperature curve (torque decreased by 5% on the second test). KPI: No white agglomerates; SEM sampling inspection showed a dispersion grade ≥ 8 (ISO11345).

[0030] S23 is mixed with 0.5-3 parts of hollow glass microspheres and 1-5 parts of boron nitride nanosheets, and sheared at 80℃ for 3 min. The true density of the hollow glass microspheres is 0.15-0.25 g / cm³. 3 The thickness of boron nitride nanosheets is ≤5nm, the premixed shear rate is 1500rpm, and the thermal conductivity of the adhesive after the thermally conductive skeleton is formed is ≥0.45W / (m·K). Specifically, premix 2 parts of hollow glass microspheres and 3 parts of boron nitride nanosheets in a premixer at 80℃ and 1500rpm for 10 minutes. Then add them all at once to a mixer and shear at 80℃ and 80rpm for 3 minutes. KPI: Thermal conductivity ≥0.45W / (m·K) (HotDisk TPS2500S).

[0031] S24 is added with 0.3-2 parts of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 60 rpm for 1 min; Specifically, reduce the rotor speed to 60 rpm and inject 1.0 part of ionic liquid from the side. Continue mixing for 1 minute and observe if the torque decreases by ≥3% again. KPI: No visible droplets in the ionic liquid; T≤85℃.

[0032] S25 is mixed with 1-3 parts of microencapsulated peroxide vulcanizing agent, 0.1-1 parts of rare earth lubricant lanthanum stearate, and 0.2-1 parts of processing aid pentaerythritol tetrastearate. The mixture is then mixed at 50-60 rpm for 2 minutes, and the discharge temperature is ≤90℃ to obtain the rubber compound.

[0033] The microcapsule wall material is composed of polyvinyl alcohol, chitosan, and fluorosilicone resin in a ratio of 5:2:3, with a wall thickness of 1-3 μm, and completely ruptures within 3 minutes at 170°C.

[0034] Specifically, mix 2 parts microencapsulated vulcanizing agent (wall material PVA:CS:fluorosilicone resin = 5:2:3, particle size 20μm), 0.5 parts lanthanum stearate, and 0.5 parts pentaerythritol tetrastearate at 50-60 rpm for 2 minutes. Clean the top plug and feed port; discharge the adhesive to the open mill and record the discharge temperature. KPI: Discharge temperature ≤ 90℃; Vulcanizing agent coating integrity ≥ 95% (laser particle size analyzer).

[0035] S3 involves grinding the rubber compound 2-3 times with three rollers, adding a secondary vulcanizing agent on an open rubber mixing mill, and then passing it through a thin mill 5-7 times to obtain a sheet. S31 passes the rubber compound through three rollers 2-3 times, with a roller gap of 0.5mm; Specifically, the three-roll mill has a roller gap of 0.5mm and cycles twice; the third roller gap is 0.3mm, and the discharge temperature is ≤50℃. KPI: The film surface is mirror-like and free of bubbles.

[0036] S32 roller temperature 50℃, add 0.2-0.5 parts of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and pass through thinly 5-7 times; Specifically, the open mill roller temperature is 50℃. After wrapping the rollers, 0.4 parts of BAPB are evenly sprinkled in. The mill is then passed through each side 3 / 4 of the way 3 times; the roller gap is adjusted to 1mm, and a thin pass is performed 6 times. KPIs: No white particles; no fluorescent enrichment observed under UV light.

[0037] S33 roller gap 2mm, unwinding 2mm, release film winding, cooling to ≤30℃.

[0038] Specifically, adjust the roller gap to 2mm and the sheet thickness to 2mm. After winding the release film, air-cool it to ≤30℃ and store it for ≤4 hours before vulcanization. KPIs: Film temperature ≤30℃; storage time ≤4 hours to prevent blooming.

[0039] S4 involves first curing the rubber sheet under light on a flat vulcanizing machine, followed by a second curing in an oven to obtain a low Mooney, high flow perfluoroether rubber.

[0040] Preheat S41 mold to 170-180℃ and spray with rare earth-fluorosilicone release agent; Specifically, preheat the mold to 175℃, polish the cavity with 320# sandpaper, and wipe it with alcohol. Spray with rare earth-fluorosilicone release agent, bake at 180℃ for 5 minutes to form a release layer ≤10nm. KPI: Mold surface temperature uniformity ±1℃ (infrared thermal imager).

[0041] S42 is vulcanized once under conditions of 10-15MPa, 170-180℃ and 10-15min. Specifically, the cut piece quality = cavity volume × 1.05, and the mold is closed quickly. The pressure is increased to 12 MPa, and the venting is performed 3 times × 3 seconds; the temperature is maintained at 175℃ for 12 minutes. KPI: First-pass vulcanization degree ≥ 90% (DSC residualcure ≤ 5%).

[0042] S43 program: heat up to 200-220℃ for 2-4 hours for secondary vulcanization, then cool with the furnace; Specifically, the programmed temperature rise is: 80℃→1h→120℃→1h→160℃→1h→210℃→2h, with a heating rate ≤1℃ / min. The furnace is then cooled to ≤60℃ before being removed from the furnace. KPIs: No secondary foaming; compression set ≤10% (300℃×168h).

[0043] S44 ethanol wiping and 23℃×50%RH standing for 24h yields low Mooney and high flow perfluoroether rubber.

[0044] Specifically, wipe the surface with anhydrous ethanol to remove mold release agent residue. Test performance after standing at 23℃ × 50%RH for 24 hours. KPIs: No blooming, no odor; Mooney rebound ≤1ML.

[0045] Beneficial effects: 1. Mooney viscosity drops sharply: raw rubber 72ML → compound rubber ≤20ML (125℃), fluidity is improved by 2.5 times, molding filling time is shortened by 40%, and low temperature molding becomes possible.

[0046] II. Complete elimination of weld lines: Spherical SiO2 "micro-bearings" + thermally conductive skeleton homogenize the mold temperature, the weld line disappearance rate is ≥98%, the appearance of the seal is mirror-like without fusion lines, and the yield rate jumps from the industry average of 85% to ≥99.5%.

[0047] III. Low-temperature rapid vulcanization: The synergistic effect of ionic liquid and microencapsulated vulcanizing agent reduces the activation energy by 15-20 kJ / mol, and complete cross-linking can be achieved at 170℃ for 12 min, resulting in a 20% reduction in energy consumption and an extended equipment life.

[0048] IV. Upgraded heat resistance: Secondary vulcanization forms an imide-peroxide composite crosslink, with a compression set of ≤10% at 300℃ for 168h, which is half that of commercially available FFKM, and the sealing life is increased by 2 times.

[0049] V. Significant cost advantages: Low-temperature molding reduces equipment wear and tear; rare earth release layer extends the mold cleaning cycle from "once per shift" to "once per week"; overall production costs decrease by approximately 15%.

[0050] VI. Scale-up capability: All steps have set quantified KPIs and online detection nodes, allowing for linear scale-up from 50L experiment to 5000L industrial reactor, with a single batch pass rate of ≥99.5%, making it ready for direct industrialization.

[0051] The above-disclosed method is merely a preferred embodiment of the present invention for preparing perfluoroether rubber. It should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing perfluoroether rubber, characterized in that, Includes the following steps: Aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer and 0.01-0.1 wt% chain transfer agent are added to a high-pressure reactor and subjected to free radical emulsion polymerization at pH=3-4, 70-80℃ and 2.0-2.5 MPa to obtain fluorinated raw rubber; 100 parts by weight of fluorinated raw rubber were put into an internal mixer, and spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant and processing aid were added in sequence. The mixture was internally mixed at 60-80℃ and 40-60rpm for 5-10 minutes. The discharge temperature was ≤90℃ to obtain the rubber compound. After the rubber compound is milled 2-3 times with three rollers, a secondary vulcanization aid is added on an open rubber mixing mill. After passing through a thin mill 5-7 times, the rubber is sheeted to obtain a rubber sheet. The rubber sheet is vulcanized once under light on a flat vulcanizing machine, and then vulcanized a second time in an oven to obtain a low Mooney, high flow perfluoroether rubber.

2. The method for preparing perfluoroether rubber according to claim 1, characterized in that, The process of "adding an aqueous phase, pH adjuster, emulsifier, 40-60 wt% tetrafluoroethylene, 15-25 wt% perfluoromethyl vinyl ether, 1-5 wt% perfluorocyano vinyl ether, 0.5-2 wt% carboxyl-terminated liquid fluoroether telomer and 0.01-0.1 wt% chain transfer agent to a high-pressure reactor and carrying out free radical emulsion polymerization under the conditions of pH=3-4, 70-80℃, and 2.0-2.5 MPa to obtain fluorinated raw rubber" includes the following steps: Add deionized water, ammonium perfluorooctanoate, and potassium dihydrogen phosphate to the high-pressure reactor. Adjust the pH to 3-4 with dilute hydrochloric acid and purge with nitrogen to remove oxygen until dissolved oxygen is ≤0.5ppm. The tetrafluoroethylene (40-60 wt%), perfluoromethyl vinyl ether (15-25 wt%), perfluorocyano vinyl ether (1-5 wt%), and carboxyl-terminated liquid fluoroether telomer (0.5-2 wt%) are sequentially pressed into the reactor. A single injection of 0.01-0.1 wt% 1-iodoperfluorobutane; Heat to 70-80℃, add potassium persulfate, and perform free radical emulsion polymerization at 2.0-2.5MPa; The mixed monomers are automatically replenished as the reaction consumes them, maintaining a constant pressure. When the conversion rate reaches 90-95%, the temperature is lowered, the pressure is released, and an aqueous solution of hydroquinone is added to terminate the process. The mixture is then coagulated, washed, and vacuum dried at 80°C to obtain 60-80 mL of Mooney fluorinated raw gum at 100°C (1+10).

3. The method for preparing perfluoroether rubber as described in claim 2, characterized in that, In the "automatic replenishment of mixed monomers as the reaction consumes, maintaining constant pressure" scenario, the monomer metering accuracy is ±0.2%, and the pressure fluctuation during the constant pressure replenishment stage is ≤±0.05MPa.

4. The method for preparing perfluoroether rubber according to claim 1, characterized in that, The process of "adding 100 parts by weight of fluorinated raw rubber to an internal mixer, and sequentially adding spherical SiO2, composite thermally conductive filler, ionic liquid, microencapsulated peroxide vulcanizing agent, rare earth lubricant, and processing aid, and mixing at 60-80℃ and 40-60rpm for 5-10 minutes, with a discharge temperature ≤90℃ to obtain the rubber compound" includes the following steps: Add 100 parts of fluorinated raw rubber to a mixer and masticate at 60°C and 60 rpm for 2 minutes. Add 5-15 parts of modified spherical SiO2 with an average particle size of 0.2-0.8 μm and a sphericity ≥0.92, and mix at 80 rpm for 1.5 min; Add 0.5-3 parts of hollow glass microspheres and 1-5 parts of boron nitride nanosheets premix, and shear at 80℃ for 3 min; Add 0.3-2 parts of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 60 rpm for 1 min; Add 1-3 parts of microencapsulated peroxide vulcanizing agent, 0.1-1 parts of rare earth lubricant lanthanum stearate, and 0.2-1 parts of processing aid pentaerythritol tetrastearate. Mix at 50-60 rpm for 2 minutes. The discharge temperature is ≤90℃ to obtain the rubber compound.

5. The method for preparing perfluoroether rubber as described in claim 3, characterized in that, The spherical SiO2 is pre-modified with KH-570+1H,1H,2H,2H-perfluorooctyltrimethoxysilane for secondary surface modification, with a grafting rate ≥6wt%; The true density of the hollow glass microspheres is 0.15-0.25 g / cm³. 3 The thickness of boron nitride nanosheets is ≤5nm, the premixed shear rate is 1500rpm, and the thermal conductivity of the adhesive after the thermally conductive skeleton is formed is ≥0.45W / (m·K). The microcapsule wall material is composed of polyvinyl alcohol, chitosan, and fluorosilicone resin in a ratio of 5:2:3, with a wall thickness of 1-3 μm, and completely ruptures within 3 minutes at 170°C.

6. The method for preparing perfluoroether rubber according to claim 1, characterized in that, The process of "grinding the rubber compound 2-3 times with three rollers, adding a secondary vulcanizing agent on an open mixing mill, passing it through a thin sheet 5-7 times, and then sheeting it to obtain a rubber sheet" includes the following steps: Pass the rubber compound through three rollers 2-3 times, with a roller gap of 0.5mm; With the roller temperature at 50℃, add 0.2-0.5 parts of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and pass through the roller 5-7 times. Adjust the roller gap to 2mm, lower the sheet by 2mm, wind up the release film, and cool to ≤30℃.

7. The method for preparing perfluoroether rubber according to claim 1, characterized in that, The process of "performing a low Mooney, high flow perfluoroether rubber by first curing the rubber sheet under light on a flat vulcanizing machine and then second curing it in an oven" includes the following steps: Preheat the mold to 170-180℃ and spray with rare earth-fluorosilicone release agent; A single vulcanization process is carried out under conditions of 10-15 MPa, 170-180℃, and 10-15 min. The temperature is increased to 200-220℃ and carried out for 2-4 hours for secondary vulcanization, followed by furnace cooling. Wiping with ethanol and standing at 23℃×50%RH for 24 hours yields a low Mooney and high flow perfluoroether rubber.

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