A perfluoroether raw rubber latex, its preparation method and application

Abstract

This invention discloses a perfluoroether raw rubber emulsion, its preparation method, and its application. Specifically, this invention provides a method for preparing a perfluoroether raw rubber emulsion, characterized by comprising the following steps: (1) in the presence of an aqueous medium, an initiator, an emulsifier, and a chain transfer agent, an initial mixed monomer undergoes an emulsion polymerization reaction; (2) the first-stage mixed monomer is continuously added to the polymerization reaction system until the polymerization reaction accumulates to 25-67% of the final yield; the percentage of the final yield is a mass percentage; (3) the second-stage mixed monomer is continuously added to the polymerization reaction system until the polymerization reaction accumulates to the final product. The perfluoroether raw rubber emulsion prepared by the method of this invention, further processed into perfluoroether raw rubber, has one or more of the following advantages: high temperature resistance, low permanent compression set, and good processing performance, and the rubber obtained after vulcanization of the perfluoroether raw rubber also has better performance parameters.

Description

Technical Field

[0001] This invention relates to a perfluoroether raw rubber emulsion, its preparation method, and its application. Background Technology

[0002] Perfluoroether rubber is a multi-component copolymer polymerized from monomers such as tetrafluoroethylene and perfluoroalkyl vinyl ethers, and is known as the "king of rubbers". The main chain structure of this rubber is a TFE structural unit. Because the radius of a fluorine atom is half the length of a "CC" bond, its main chain possesses the excellent high-temperature resistance and chemical resistance of polytetrafluoroethylene (PTFE). Furthermore, the -OCF3 groups in the side chains disrupt the crystallinity of the PTFE main chain segments, giving it a certain degree of elasticity, making it suitable for applications in elastic sealing.

[0003] This type of rubber exhibits excellent resistance to oils, chemicals, and high temperatures, reaching up to 327°C. o It can operate effectively under C. It can withstand corrosion from almost all chemical media, including ethers, ketones, benzene ring solvents, strong oxidants, and strong acids and bases (currently known to be resistant to 1600 solvents except for fluorinated solvents). However, it may swell in some high-fluorine carbon solvents. If it comes into contact with gaseous or molten alkali metals, there is a risk of causing a violent chemical reaction.

[0004] The high bond energy of the CF bond is the main reason for the high stability of perfluoroelastomers (PFEs). PFEs exhibit superior high-temperature compression set compared to other fluororubbers. These excellent properties have led to their widespread application in numerous fields, including aerospace, petrochemicals, nuclear energy, semiconductor manufacturing, pharmaceuticals, food, and office equipment.

[0005] Besides its molecular structure, the properties of perfluoroelastomers are closely related to their crosslinking structure. Ordinary perfluoroelastomers, especially those vulcanized with peroxides, are primarily designed for use in harsh environments, with a high-temperature operating temperature of 230°C. o C. In the early 21st century, Solvay, an Italian company, developed a peroxide-initiated crosslinking agent for high-temperature resistant perfluoroether vulcanization, which improved the resistance to media and high temperatures of PFR95HT perfluoroether rubber, achieving a maximum service temperature of 300°C. o Temperatures above 325°C. Cyano-cured perfluoroether rubber, using amine vulcanizing agents or after the formation of triazine structures between macromolecules, can achieve a maximum operating temperature of 325°C. o C, such as the Kalrez series products from DuPont in the United States.

[0006] With the rapid development of my country's aerospace and high-end equipment manufacturing industries, the domestic demand for high-performance perfluoroelastomer (PFE) rubber is increasing year by year. However, the current domestic market for PFE rubber composite materials and products mainly comes from DuPont (USA), Solvay (Italy), Daikin (Japan), and well-known international sealing suppliers such as Freudenberg-NOK, Parker, PPE (UK), and Greene Tweed (USA). Globally, DuPont's PFE rubber remains the industry benchmark, as its PFE materials offer a wide range of types and applications suitable for different temperatures and media.

[0007] Currently, most domestic research and development of perfluoroether rubber focuses only on material performance, such as resistance to 280°C. o C, 300 o C and over 300 o All perfluoroethers of C are still under development, and mature processes are not yet available. Furthermore, there are few reports on the emulsion polymerization mechanism of fluorinated monomers and the process for synthesizing raw rubber. Therefore, it is urgent for us to conduct in-depth research on the emulsion copolymerization reaction of fluorinated monomers, explore the copolymerization reaction rules of gas-liquid two-phase fluorinated monomers, and synthesize high-temperature resistant (325℃) perfluoroethers. o C) Perfluoroether raw rubber provides the core technology and foundation for the development of high-performance fluoroether rubber. Summary of the Invention

[0008] To address the deficiency in existing technologies regarding the limited variety of high-temperature resistant perfluoroether raw rubbers, this invention provides a high-temperature resistant perfluoroether raw rubber emulsion, its preparation method, and its applications. The perfluoroether raw rubber emulsion prepared by the method of this invention, further processed into perfluoroether raw rubber, possesses one or more of the following advantages: high-temperature resistance, low permanent compression set, and good processability. Furthermore, the rubber obtained after vulcanization of this perfluoroether raw rubber exhibits superior performance parameters.

[0009] The present invention mainly solves the above-mentioned technical problems through the following technical solutions.

[0010] This invention provides a method for preparing a perfluoroether raw rubber latex, comprising the following steps:

[0011] (1) In the presence of an aqueous medium, an initiator, an emulsifier and a chain transfer agent, the initially mixed monomers undergo emulsion polymerization;

[0012] (2) Continuously add the first-stage mixed monomers to the polymerization reaction system until the cumulative polymerization reaction reaches 25-67% of the final yield; the percentage of the final yield is a mass percentage;

[0013] (3) Continuously add the second-stage mixed monomers to the polymerization reaction system until the polymerization reaction accumulates to the final yield;

[0014] The initial mixed monomers include tetrafluoroethylene and perfluoromethyl vinyl ether. The first-stage mixed monomers include a sulfurization point monomer, tetrafluoroethylene, and perfluoromethyl vinyl ether. The second-stage mixed monomers include a sulfurization point monomer, tetrafluoroethylene, perfluoromethyl vinyl ether, and perfluorooxazine vinyl ether.

[0015] In a preferred embodiment of the present invention, in step (1), a portion of the initial mixed monomer is first introduced into the reaction system to make the oxygen content in the reaction system less than 30~35ppm. After the temperature is controlled to the reaction temperature, the initial mixed monomer is introduced to the pressure of step (1).

[0016] As a preferred embodiment of the present invention, in step (2), the first-stage mixed monomers are added until the cumulative polymerization reaction reaches 27-55% of the final yield; preferably until the cumulative polymerization reaction reaches 40-53% of the final yield, and more preferably until the cumulative polymerization reaction reaches 44-49% of the final yield; the first-stage mixed monomers are added until the cumulative polymerization reaction reaches 46%-48% of the final yield; for example, 47% or 48%.

[0017] As a preferred embodiment of the present invention, the reaction time of step (2) is 1.5 to 4.5 hours; preferably 2 to 4 hours; more preferably 2.8 to 3.2 hours; for example 3 hours.

[0018] As a preferred embodiment of the present invention, the reaction time of step (3) is 3.5 to 6 hours; preferably 4.5 to 5.5 hours, for example 5 hours.

[0019] As a preferred embodiment of the present invention, the pressure in step (1) is 2.4~2.6 MPa, for example 2.5 or 2.6 MPa.

[0020] As a preferred embodiment of the present invention, step (2) is performed when the pressure drops by 0.2 MPa in step (1).

[0021] As a preferred embodiment of the present invention, the pressure in step (2) is 2.4~2.6 MPa, for example 2.5 or 2.6 MPa.

[0022] As a preferred embodiment of the present invention, in step (2), the first stage mixed monomer is added back to the original pressure for every 0.2 MPa decrease in the pressure of the reaction system.

[0023] As a preferred embodiment of the present invention, the pressure in step (3) is 2.7~2.9 MPa, for example 2.7 or 2.8 MPa.

[0024] In a preferred embodiment of the present invention, in step (3), the pressure of the reactor system is maintained by continuously introducing the second-stage mixed monomer.

[0025] In a preferred embodiment of the present invention, the molar ratio of tetrafluoroethylene to perfluoromethyl vinyl ether in the initial mixed monomer is (40-55):(45-60); for example, 40:60, 45:55, 50:50 or 55:45.

[0026] In a preferred embodiment of the present invention, in step (3), before adding the second stage mixed monomer, the initial mixed monomer is introduced to the pressure of step (3), and the initiator is added. The mass ratio of the added initiator to the water medium is (0.03-0.2):100, preferably (0.06-0.15):100; for example, 0.2:300, 0.3:300 or 0.4:300.

[0027] In a preferred embodiment of the present invention, the sulfidation point monomer is a cyano-containing sulfidation point monomer, wherein the cyano-containing sulfidation point monomer is selected from CF2=CF-OR. f1 -OR f2 -CN or one or more combinations, R f1 and R f2 Independently for perfluorinated C 2-10 Alkylenes, such as perfluorinated C 2-6 Alkylene; the sulfidation point monomer is preferably perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene) (i.e., CF2=CF-O-CF2-CF(CF3)-O-CF2-CF2-CN, 8-CNVE);

[0028] In a preferred embodiment of the present invention, the perfluorooxoalkyl vinyl ether is bonded by one, two, or three C atoms. 1-6 Perfluoroalkoxy-substituted perfluoroalkyl vinyl ethers, more preferably perfluoromethoxypropyl vinyl ethers.

[0029] As a preferred embodiment of the present invention, the molar ratio of tetrafluoroethylene, perfluoromethyl ethylene and sulfide point monomer ether in the first stage mixed monomer is (50-75):(25-40):(1-2); for example, 61:38:1, 65:34:1, 70:28:2 or 70:29:1.

[0030] In a preferred embodiment of the present invention, the molar ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, perfluorooxane vinyl ether and sulfidation point monomer in the second stage mixed monomer is (50-75):(15-25):(5-25):(1-2); for example, 61:18:20:1, 65:20:14:1, 70:18:10:2 or 70:20:9:1.

[0031] In a preferred embodiment of the present invention, the initiator is a persulfate, such as one or more selected from potassium persulfate, sodium persulfate, and ammonium persulfate, preferably potassium persulfate or ammonium persulfate.

[0032] In a preferred embodiment of the present invention, in step (1), the mass ratio of the amount of initiator added to the water medium is (0.05-0.3):100, more preferably (0.1-0.15):100; for example, 0.1:100.

[0033] As a preferred embodiment of the present invention, the initiator is added in batches after the polymerization reaction begins. Preferably, the initiator is added every 15 to 30 minutes in steps (2) and (3), for example, every 20 to 25 minutes. More preferably, the mass ratio of the amount of initiator added each time to the water medium is (0.01 to 0.1): 100, more preferably (0.03 to 0.05): 100; for example, 0.1: 300 or 0.15: 300.

[0034] In a preferred embodiment of the present invention, the chain transfer agent is an iodine-containing fluoroalkane I (CF2). n I, where n = 2 to 7; preferably, the chain transfer agent is selected from one or more of (perfluoro)1,2-diiodoethane, 1,4-perfluorobutyldiiodide, 1,5-perfluoropentyldiiodide, and 1,6-perfluorohexyldiiodide, more preferably 1,6-perfluorohexyldiiodide;

[0035] In a preferred embodiment of the present invention, the mass ratio of the chain transfer agent to the water medium is (0.05-0.3):100, more preferably (0.1-0.2):100; for example, 0.1:100, 0.13:100 or 0.2:100.

[0036] In a preferred embodiment of the present invention, the emulsifier is a mixture of perfluoropolyether peroxide and sodium octyl sulfonate, preferably with a mass ratio of perfluoropolyether peroxide to sodium octyl sulfonate of 1:1; preferably, the perfluoropolyether peroxide is... In a preferred embodiment of the present invention, the mass ratio of the emulsifier to the water medium is (0.01-0.3):100, more preferably (0.02-0.05):100; for example, 0.02:100, 0.07:300, 0.08:300 or 0.03:100.

[0037] In a preferred embodiment of the present invention, a pH adjuster is added to the polymerization reaction system during the polymerization reaction. The pH adjuster is selected from one or more combinations of ammonium carbonate, ammonium bicarbonate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate, preferably disodium hydrogen phosphate. Preferably, the mass ratio of the added pH adjuster to the water medium is (0.05-1):100, more preferably (0.05-0.15):100; for example, 0.1:100, 0.07:100, or 0.05:100. The pH adjuster can control the pH value of the medium within a certain range to ensure the reactivity of the initiator.

[0038] In a preferred embodiment of the present invention, the amount of perfluoroether raw rubber formed by the polymerization reaction is approximately equal to the amount of added mixed monomers, ranging from 25 to 55 parts by weight of perfluoroether raw rubber per 100 parts by weight of aqueous medium, preferably 30 to 40 parts by weight of perfluoroether raw rubber per 100 parts by weight of aqueous medium. This is because if the weight of perfluoroether raw rubber in the aqueous medium is too small, the yield will be too low, increasing costs; while if the weight is too large, the solid content will be too high, resulting in a viscous emulsion with low stability and low heat transfer efficiency.

[0039] In a preferred embodiment of the present invention, the polymerization reaction is carried out under mechanical stirring, wherein the stirring speed is preferably 500-900 rpm, more preferably 600-800 rpm, for example 700 rpm.

[0040] When the stirring rate is too low, the small shear force is insufficient to disperse the liquid monomers, resulting in larger droplets or even stratification. This restricts the entry of droplets into micelles, which is detrimental to polymerization. Conversely, when the stirring rate is too high, the strong shear force will cause the emulsion to demulsify and coagulate in the reactor, which is also detrimental to the reaction.

[0041] In a preferred embodiment of the present invention, the polymerization reaction temperature is 65–90°C. o C, preferably 80-85 o C; for example, 80℃ or 85℃.

[0042] If the temperature is below 65 degrees Celsius o C, the polymerization rate is too slow and unsuitable for large-scale industrial production. If the temperature is above 90°C... oC causes the initiator to decompose too quickly, resulting in waste. It also accelerates the polymerization reaction, making the reaction process difficult to control, easily leading to heat accumulation and "explosive polymerization." Furthermore, it cannot effectively control the polymer chain structure.

[0043] In a preferred embodiment of the present invention, the polymerization reaction is carried out in a reactor, and the space left after the water medium is added to the reactor is a vapor space where gaseous monomers exist. The vapor space is 30-50% of the reactor volume, preferably 40%.

[0044] As a preferred embodiment of the present invention, step (1) includes the following steps: in the presence of an aqueous medium, the initial mixed monomers are heated to 65~90 ℃ (e.g. 80 ℃), and then the chain transfer agent, the initiator and the emulsifier are added.

[0045] In a preferred embodiment of the present invention, the preparation method of the perfluoroether raw rubber latex includes the following steps:

[0046] (1) In the presence of an aqueous medium, partially replace the air by introducing the initial mixed monomers into the reaction system, followed by mechanical stirring and heating until the temperature of the reaction solution stabilizes at 80–85°C. o After step C, the initial mixed monomers are introduced to bring the pressure of the reaction system to 2.4~2.6 MPa. Then, the first batch of initiator is added to initiate the polymerization reaction. Subsequently, emulsifier, pH adjuster and chain transfer agent are added. The mass ratio of the first batch of initiator to the water medium is (0.1~0.15):100.

[0047] (2) For every 0.2 MPa decrease in the reaction system pressure, the first stage mixed monomer is added to maintain the reaction system pressure at 2.4~2.6 MPa until the polymerization reaction accumulates to 44~48% of the final yield. During this process, the initiator is added in batches every 20~25 minutes, and the mass ratio of the amount of initiator added to the water medium each time is (0.03~0.05):100 to maintain the polymerization reaction.

[0048] (3) The initial mixed monomers are introduced again to make the reaction pressure reach 2.7~2.9 MPa, and the second batch of initiator is added. The mass ratio of the amount of the second batch of initiator to the water medium is (0.06~0.15):100. Polymerization is carried out. For every 0.2 MPa decrease in the reaction system pressure, the second stage mixed monomers are added to maintain the reaction system pressure at 2.7~2.9 MPa. During this process, the initiator is added in batches every 20~25 minutes. The mass ratio of the amount of initiator added each time to the water medium is (0.03~0.05):100. The polymerization reaction is maintained until the final yield is obtained, and the perfluoroether raw rubber latex is prepared.

[0049] Preferably, except for the specifically defined reactants, their proportions, reaction conditions, and reaction operations, the preferred embodiments and other undefined reactants, their proportions, reaction conditions, and reaction operations in the above preparation methods are as described in any of the preceding embodiments.

[0050] The method for preparing perfluoroether raw rubber emulsion provided by this invention allows for the control and adjustment of the structure of the obtained copolymer by using different reactive monomers at different reaction stages, resulting in emulsion products with better performance.

[0051] The present invention also provides a perfluoroether raw rubber latex, which is prepared by the above-described preparation method.

[0052] The present invention also provides a perfluoroether raw rubber, which is obtained by coagulating, washing and drying the perfluoroether raw rubber emulsion.

[0053] In a preferred embodiment of the present invention, the emulsion is subjected to coagulation treatment with magnesium chloride, for example, 5% wt magnesium chloride is used for coagulation treatment.

[0054] In a preferred embodiment of the present invention, the vacuum drying temperature is 85–110 °C. o C, a more preferred vacuum drying temperature is 95°C. o C.

[0055] In a preferred embodiment of the present invention, the perfluoroether raw rubber has a fluorine content of 68% or more, preferably 72% or more.

[0056] The present invention also provides the application of any of the aforementioned perfluoroether raw rubbers in the preparation of rubber.

[0057] The present invention also provides a vulcanized rubber obtained by vulcanizing the perfluoroether raw rubber described in any of the foregoing embodiments.

[0058] In a preferred embodiment of the present invention, the vulcanization includes the following steps: the perfluoroether raw rubber is mixed with bis(2,5)-vinyl chloride, TAIC and carbon black N990 and then vulcanized in stages, the first stage of vulcanization being: vulcanization conditions 170~190°C. o C×10 min, pressure 10~15 MPa; two-stage vulcanization: vulcanization conditions 220~240 o The vulcanized rubber is prepared by heating for 4 hours (C×4 h).

[0059] As a preferred embodiment of the present invention, the mixing includes the following steps: first, the perfluoroether raw rubber is mixed with bis(2,5)-vinyl chloride, TAIC and carbon black N990 until there is no obvious difference in the rubber compound, and then the mixture is thinly mixed 8 to 12 times in a triangular bag.

[0060] In a preferred embodiment of the present invention, the mixing temperature does not exceed 60°C.

[0061] In a preferred embodiment of the present invention, the vulcanization condition is 177. o C×10 min, pressure 10~15 MPa.

[0062] In a preferred embodiment of the present invention, the conditions for the two-stage vulcanization are 230°C. o C×4 h.

[0063] The perfluoroether raw rubber synthesized in this invention has high temperature resistance (325°C). o C) Advantages include low permanent compression set and good processability. Compared with perfluoroether raw rubber obtained by direct mixing and emulsion polymerization using the same formula, the perfluoroether raw rubber prepared by this invention has a higher heat resistance temperature. Detailed Implementation

[0064] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the specific embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available conventional products.

[0065] Test method:

[0066] Tensile strength was tested using national standards GB / T1447 and 3354-2014.

[0067] The elongation at break is in accordance with the national standard GB / T 10654-2001.

[0068] The national standard for testing the rate of change of tensile strength is the method specified in GB 36246.

[0069] The national standard for testing elongation at break is GB / T 228-2002.

[0070] Hardness testing was conducted according to GB / T531-2008.

[0071] The compression set test method is based on GB / T7759-1996, and the test conditions are: Type A specimen, 300 °C. o C×70 h.

[0072] Mooney viscosity of raw rubber ML(1+10) 121 o C test is conducted according to GB / T1232-2000.

[0073] Glass transition temperature T g The test was conducted in accordance with GB / T19466-2004.

[0074] Density testing was conducted according to the national standard GB / T 1463.

[0075] Fluorine content was determined using an electrochemical method.

[0076] Preparation of perfluoropolyether peroxides:

[0077] Add 25 mL of water and 4 g of NaOH to a 100 mL flask and stir in an ice-water bath.

[0078] Add 25 mL of perfluorooctane and 5.75 g of H2O2 to the system, then add 33.6 g of hexafluoropropylene oxide dimer dropwise. After the addition is complete, react for three minutes, add an equal volume of NaHCO3, extract the lower organic phase, and dry with anhydrous sodium sulfate.

[0079] The organic phase was extracted, stored in a plastic bottle at a concentration of 0.86 mmol / mL, and refrigerated.

[0080] Example 1

[0081] This embodiment provides a perfluoroether raw rubber, and the specific preparation method is as follows:

[0082] Add 3 kg of deionized water to a 5 L reactor equipped with a stirring device. Before the experiment, evacuate the activated reactor and the gas and liquid pipelines connecting the reactor body. Purge the pipelines and reactor body with nitrogen. Then, use a diaphragm compressor to introduce the initial mixed monomers tetrafluoroethylene (TFE) / perfluoromethyl vinyl ether (PMVE) = 40 / 60 (molar ratio) into the reactor to replace the nitrogen and make the oxygen content in the reactor less than 30 ppm.

[0083] Turn on the electromagnetic stirrer, set the heating temperature, and the system will begin stirring and heating. The mechanical stirring speed is 700 rpm. Wait until the liquid temperature in the vessel stabilizes at 80°C. oAt step C, the pre-packaged initial mixed monomers TFE / PMVE = 40 / 60 (molar ratio) are pumped into the reactor using a diaphragm compressor to achieve a reactor pressure of 2.5 MPa, while maintaining controlled reaction pressure. 3 g of ammonium persulfate (2M, aqueous solution) as initiator is added to the reactor to initiate polymerization. 0.6 g of emulsifier (a 1:1 mass ratio of perfluoropolyether peroxide to sodium octyl sulfonate), 1.5 g of disodium hydrogen phosphate as a pH adjuster, and 3 g of 1,6-perfluorohexyl diiodophosphate (CAS: 375-80-4) as a chain transfer agent are added, and the mixture is heated to 80°C. o C.

[0084] The experiment employed a continuous emulsion copolymerization scheme. As polymerization progressed, the system pressure was replenished with the mixed monomers from the first reaction stage to restore the original pressure for every 0.2 MPa decrease. The mixed monomers from the first reaction stage, TFE / PMVE / 8-CNVE = 61 / 38 / 1 (molar ratio), were added to the reactor via a diaphragm compressor to maintain a constant pressure within the reactor. Potassium persulfate initiator (1 g) was added every 20 minutes to ensure effective reaction. After 3 hours of polymerization, the second reaction stage began, at which point the addition of the mixed monomers from the first reaction stage was stopped, and unreacted monomers were recovered from the reactor.

[0085] Subsequently, an initial mixed monomer mixture of TFE / PMVE = 40 / 60 (molar ratio) was introduced into the reactor. When the pressure inside the reactor reached 2.8 MPa, 2 g of potassium persulfate initiator was added to initiate the polymerization reaction. The second reaction stage mixed monomer mixture of TFE / PMVE / 8-CNVE / PAVE = 61 / 18 / 1 / 20 (molar ratio) was continuously introduced, and 1 g of potassium persulfate initiator was added every 20 minutes during the polymerization process to maintain the effective reaction for five hours. PAVE (perfluorooxazine vinyl ether) was perfluoromethoxypropyl vinyl ether (CAS: 40573-09-9).

[0086] During polymerization, constant monitoring of system temperature is crucial, especially for highly reactive monomers. Emulsion polymerization releases heat to a certain extent; failure to control this can lead to localized overheating, accelerating initiator decomposition, and even causing "explosive polymerization." Therefore, continuous temperature control and recording are essential. Additionally, accurate recording of system pressure changes over time is vital. After the second stage of reaction, stop adding mixed monomers. When the system pressure drops to 1.9 MPa, stop stirring and allow it to cool to a safe temperature before discharging. Recover unreacted monomers from the reactor. The material flowing out of the coil reactor enters the product collection device, yielding the perfluoroether raw rubber emulsion. Add 5% wt magnesium chloride to the obtained perfluoroether raw rubber emulsion for coagulation, then wash, and finally... (The sentence is incomplete and ends abruptly). oVacuum drying at C for 24 h yielded 1.3 kg of perfluoroether raw rubber product.

[0087] The product mass at the completion of the first stage reaction accounts for 47% of the product mass at the completion of the second stage reaction.

[0088] Example 2

[0089] This embodiment provides a perfluoroether raw rubber, and the specific preparation method is as follows:

[0090] Add 3 kg of deionized water to a 5 L reactor equipped with a stirring device. Before the experiment, evacuate the activated reactor and the gas and liquid pipelines connecting the reactor body. Purge the pipelines and reactor body with nitrogen. Then, use a diaphragm compressor to introduce the initial mixed monomers tetrafluoroethylene (TFE) / perfluoromethyl vinyl ether (PMVE) = 45 / 55 (molar ratio) into the reactor to replace the nitrogen and make the oxygen content in the reactor less than 30 ppm.

[0091] Turn on the electromagnetic stirrer, set the heating temperature, and the system will begin stirring and heating. The mechanical stirring speed is 700 rpm. Wait until the liquid temperature in the vessel stabilizes at 85°C. o At step C, the pre-packaged initial mixed monomers TFE / PMVE (molar ratio 45 / 55) are pumped into the reactor using a diaphragm compressor to achieve a reactor pressure of 2.6 MPa, while maintaining controlled reaction pressure. 3 g of ammonium persulfate (2M aqueous solution) is then added to the reactor to initiate polymerization. 0.7 g of emulsifier (a 1:1 mass ratio of perfluoropolyether peroxide and sodium octyl sulfonate), 2 g of disodium hydrogen phosphate (pH adjuster), and 4 g of 1,6-perfluorohexyl diiodide (chain transfer agent) are added, and the mixture is heated to 85°C. o C.

[0092] The experiment employed a continuous emulsion copolymerization scheme. As polymerization progressed, the system pressure was replenished with the mixed monomers from the first reaction stage to restore the original pressure for every 0.2 MPa decrease. The mixed monomers from the first reaction stage, TFE / PMVE / 8-CNVE (molar ratio 65 / 34 / 1), were added to the reactor via a diaphragm compressor to maintain a constant pressure within the reactor. Potassium persulfate initiator (1 g) was added every 20 minutes to ensure effective reaction. After 3 hours of polymerization, the second reaction stage began, at which point the addition of the mixed monomers from the first reaction stage was stopped, and unreacted monomers were recovered from the reactor.

[0093] Subsequently, an initial mixed monomer mixture of TFE / PMVE = 45 / 55 (molar ratio) was introduced into the reactor. When the pressure inside the reactor reached 2.8 MPa, 2 g of potassium persulfate initiator was added to initiate the polymerization reaction. The second reaction stage mixed monomer mixture of TFE / PMVE / 8-CNVE / PAVE = 65 / 20 / 1 / 14 (molar ratio) was continuously introduced, and 1.5 g of potassium persulfate initiator was added every 20 minutes during the polymerization process to maintain the effective reaction for five hours. PAVE (perfluorooxazine vinyl ether) is perfluoromethoxypropyl vinyl ether.

[0094] During polymerization, it is crucial to constantly monitor system temperature changes, especially for highly reactive monomers. Emulsion polymerization releases heat to a certain extent, and if not controlled in time, this can lead to localized overheating, accelerating initiator decomposition, and even causing "explosive polymerization." Therefore, it is essential to continuously control and record the reaction temperature. Additionally, it is vital to accurately record pressure changes within the system over time. After the second stage of the reaction is complete, the addition of mixed monomers is stopped. When the system pressure drops to 1.9 MPa, stirring is stopped, and the mixture is allowed to cool to a safe temperature before discharge. Unreacted monomers are recovered from the reactor, and the material flowing out of the coil reactor enters the product collection device, yielding the perfluoroether raw rubber emulsion.

[0095] Add 5% wt magnesium chloride to the prepared perfluoroether raw rubber latex to induce coagulation, then wash, and then... (The sentence is incomplete and requires more context to translate accurately.) o Vacuum drying at C for 24 h yielded 1.4 kg of perfluoroether raw rubber product.

[0096] The product mass at the completion of the first stage reaction accounts for 48% of the product mass at the completion of the second stage reaction.

[0097] Example 3

[0098] This embodiment provides a perfluoroether raw rubber latex, and the specific preparation method is as follows:

[0099] Add 3 kg of deionized water to a 5 L reactor equipped with a stirring device. Before the experiment, evacuate the activated reactor and the gas and liquid pipelines connecting the reactor body. Purge the pipelines and reactor body with nitrogen. Then, use a diaphragm compressor to introduce the initial mixed monomers tetrafluoroethylene (TFE) / perfluoromethyl vinyl ether (PMVE) = 50 / 50 (molar ratio) into the reactor to replace the nitrogen and make the oxygen content in the reactor less than 30 ppm.

[0100] Turn on the electromagnetic stirrer, set the heating temperature, and the system will begin stirring and heating. The mechanical stirring speed is 700 rpm. Wait until the liquid temperature in the vessel stabilizes at 80°C. oAt step C, the pre-packaged initial mixed monomers TFE / PMVE = 50 / 50 (molar ratio) are pumped into the reactor using a diaphragm compressor to achieve a reactor pressure of 2.5 MPa, while maintaining controlled reaction pressure. 3 g of ammonium persulfate aqueous initiator is then added to the reactor to initiate polymerization. 0.9 g of emulsifier (a 1:1 mass ratio mixture of perfluoropolyether peroxide and sodium octyl sulfonate), 3 g of dipotassium hydrogen phosphate (pH adjuster), and 6 g of 1,6-perfluorohexyl diiodophosphate (chain transfer agent) are added, and the mixture is heated to 85°C. o C.

[0101] The experiment employed a continuous emulsion copolymerization scheme. As polymerization progressed, the system pressure was replenished with the mixed monomers from the first reaction stage to restore the original pressure for every 0.2 MPa decrease. The mixed monomers from the first reaction stage, TFE / PMVE / 8-CNVE = 70 / 28 / 2 (molar ratio), were added to the reactor via a diaphragm compressor to maintain a constant pressure within the reactor. Every 25 minutes, 1.5 g of potassium persulfate initiator was added to maintain effective reaction. After 3 hours of polymerization, the second reaction stage began, at which point the addition of the mixed monomers from the first reaction stage was stopped, and unreacted monomers were recovered from the reactor.

[0102] The second reaction stage then begins. An initial mixed monomer mixture of TFE / PMVE (50 / 50 molar ratio) is introduced into the reactor. When the pressure inside the reactor reaches 2.8 MPa, 4 g of potassium persulfate initiator is added to initiate the polymerization reaction. The mixed monomer mixture of TFE / PMVE / 8-CNVE / PAVE (70 / 18 / 2 / 10 molar ratio) is continuously introduced, and 1.5 g of potassium persulfate initiator is added every 25 minutes during the polymerization process to maintain the reaction for five hours. PAVE (perfluorooxazine vinyl ether) is perfluoromethoxypropyl vinyl ether.

[0103] During polymerization, it is crucial to constantly monitor system temperature changes, especially for highly reactive monomers. Emulsion polymerization releases heat to a certain extent, and if not controlled in time, this can lead to localized overheating, accelerating initiator decomposition, and even causing "explosive polymerization." Therefore, it is essential to continuously control and record the reaction temperature. Additionally, it is vital to accurately record pressure changes within the system over time. After the second stage of the reaction is complete, the addition of mixed monomers is stopped. When the system pressure drops to 1.9 MPa, stirring is stopped, and the mixture is allowed to cool to a safe temperature before discharge. Unreacted monomers are recovered from the reactor, and the material flowing out of the coil reactor enters the product collection device, yielding the perfluoroether raw rubber emulsion.

[0104] Add 5% wt magnesium chloride to the prepared perfluoroether raw rubber latex to induce coagulation, then wash, and finally... oVacuum drying at C for 24 h yielded 1.2 kg of perfluoroether raw rubber product.

[0105] The product mass at the completion of the first stage reaction accounts for 47% of the product mass at the completion of the second stage reaction.

[0106] Example 4

[0107] This embodiment provides a perfluoroether raw rubber latex, and the specific preparation method is as follows:

[0108] Add 3 kg of deionized water to a 5 L reactor equipped with a stirring device. Before the experiment, evacuate the activated reactor and the gas and liquid pipelines connecting the reactor body. Purge the pipelines and reactor body with nitrogen. Then, use a diaphragm compressor to introduce the initial mixed monomers tetrafluoroethylene (TFE) / perfluoromethyl vinyl ether (PMVE) = 55 / 45 (molar ratio) into the reactor to replace the nitrogen and make the oxygen content in the reactor less than 30 ppm.

[0109] Turn on the electromagnetic stirrer, set the heating temperature, and the system will begin stirring and heating. The mechanical stirring speed is 700 rpm. Wait until the liquid temperature in the vessel stabilizes at 80°C. o At step C, the pre-packaged initial mixed monomers TFE / PMVE (55 / 45 molar ratio) are pumped into the reactor using a diaphragm compressor to achieve a reactor pressure of 2.6 MPa, while maintaining controlled reaction pressure. 3 g of ammonium persulfate aqueous initiator is then added to the reactor to initiate polymerization. 0.8 g of emulsifier (a 1:1 mass ratio of perfluoropolyether peroxide to sodium octyl sulfonate), 2 g of dipotassium hydrogen phosphate (pH adjuster), and 4 g of 1,6-perfluorohexyl diiodophosphate (chain transfer agent) are added, and the mixture is heated to 85°C. o C.

[0110] The experiment employed a continuous emulsion copolymerization scheme. As polymerization progressed, monomer was added to restore the system pressure to its original level whenever the system pressure dropped by 0.2 MPa. A diaphragm compressor pump was used to add the mixed monomers from the first reaction stage (TFE / PMVE / 8-CNVE = 70 / 29 / 1, molar ratio) to the reactor to maintain a constant pressure. Potassium persulfate initiator (1 g) was added every 25 minutes to ensure the reaction proceeded effectively. After 3 hours of polymerization, the second reaction stage began. At this stage, the addition of the mixed monomers from the first reaction stage was stopped, and unreacted monomers were recovered from the reactor.

[0111] The second reaction stage then begins. An initial mixed monomer mixture of TFE / PMVE (55 / 45 molar ratio) is introduced into the reactor. When the pressure inside the reactor reaches 2.7 MPa, 3 g of potassium persulfate initiator is added to initiate the polymerization reaction. The mixed monomer mixture of TFE / PMVE / 8-CNVE / PAVE (70 / 20 / 1 / 9 molar ratio) is continuously introduced, and 1 g of potassium persulfate initiator is added every 25 minutes during the polymerization process to maintain the reaction for five hours. PAVE (perfluorooxazine vinyl ether) is perfluoromethoxypropyl vinyl ether.

[0112] During polymerization, it is crucial to constantly monitor system temperature changes, especially for highly reactive monomers. Emulsion polymerization releases heat to a certain extent, and if not controlled in time, this can lead to localized overheating, accelerating initiator decomposition, and even causing "explosive polymerization." Therefore, it is essential to continuously control and record the reaction temperature. Additionally, it is vital to accurately record pressure changes within the system over time. After the second stage of the reaction is complete, the addition of mixed monomers is stopped. When the system pressure drops to 1.9 MPa, stirring is stopped, and the mixture is allowed to cool to a safe temperature before discharge. Unreacted monomers are recovered from the reactor, and the material flowing out of the coil reactor enters the product collection device, yielding the perfluoroether raw rubber emulsion.

[0113] Add 5% wt magnesium chloride to the prepared perfluoroether raw rubber latex to induce coagulation, then wash, and finally... o Vacuum drying at C for 24 h yielded 1.1 kg of perfluoroether raw rubber product.

[0114] The product mass at the completion of the first stage reaction accounts for 47% of the product mass at the completion of the second stage reaction.

[0115] Examples 5-10

[0116] The reaction was carried out in a 5L reactor according to the steps of Example 1, and the different reaction conditions are shown in Table 1. PAVE (perfluorooxazine vinyl ether) is perfluoromethoxypropyl vinyl ether.

[0117] With a total reaction time of 8 hours as the standard, the time of the first reaction stage was changed, and the performance parameters of the raw rubber were tested as shown in Table 1.

[0118] Table 1

[0119]

[0120] The percentage of yield to final yield refers to the percentage of the product mass when the first stage reaction is completed compared to the product mass when the second stage reaction is completed.

[0121] Examples 11-17

[0122] The reaction was carried out in a 5 L reactor according to the steps of Example 1, and the different reaction conditions are shown in Table 2. PAVE is perfluoromethoxypropyl vinyl ether.

[0123] Using the first reaction stage time of 3 hours as a benchmark, the total reaction time was varied, and the performance parameters of the raw rubber were tested as shown in Table 2.

[0124] Table 2

[0125]

[0126] Example 18

[0127] The properties of the raw rubber obtained in Examples 1-4 were tested, and the results are shown in Table 3.

[0128] The perfluoroether raw rubbers obtained in Examples 1-4 were vulcanized, and the properties of the vulcanized rubber products were tested. The testing steps are as follows:

[0129] (1) Perfluoroether raw rubber (100 phr) was separately heated at 25°C. o On an open-face rubber mixing mill, plasticize the raw rubber 6-8 times and observe its processing performance to obtain processing performance parameters such as "temperature during roll wrapping" and "dripping material during roll wrapping".

[0130] (2) Add bis(2,5)-vinyl chloride (4 phr), TAIC (3 phr), and carbon black N990 (30 phr) and mix until there is no obvious difference in the rubber compound. Then, mix in a thin pass using a triangular bag for 8-12 times, with the mixing temperature not exceeding 60°C. o C. The film is then subjected to segmented vulcanization. The first stage of vulcanization: vulcanization conditions 177 o C×10 min, pressure 10~15 MPa; two-stage vulcanization: vulcanization conditions at atmospheric pressure 230 o C×4 h, then perform the following data testing and analysis.

[0131] Methods for determining the processing performance of raw rubber: Observe the temperature at which the raw rubber can quickly wrap around the rolls on an open mill, and measure the temperature of the raw rubber with a handheld infrared thermometer; and weigh the flocculent, granular or blocky drips (size less than 10x10x10 mm) of the raw rubber during the entire roll wrapping process.

[0132] Table 3

[0133]

[0134] The test results show that the perfluoroether raw rubber provided in this application has a high fluorine content and good mechanical properties. After aging at 325℃ for 24h, the change rate of tensile strength and the change rate of elongation at break are both low, and the parameters of the vulcanized rubber are also better.

[0135] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing a perfluoroether raw rubber latex, characterized in that, It includes the following steps: (1) In the presence of an aqueous medium, an initiator, an emulsifier and a chain transfer agent, the initially mixed monomers undergo emulsion polymerization; (2) Continuously add the first-stage mixed monomers to the polymerization reaction system until the cumulative polymerization reaction reaches 25-67% of the final yield; the percentage of the final yield is a mass percentage; (3) Continuously add the second-stage mixed monomers to the polymerization reaction system until the polymerization reaction accumulates to the final yield; The initial mixed monomers include tetrafluoroethylene and perfluoromethyl vinyl ether; the first stage mixed monomers include a sulfur point monomer, tetrafluoroethylene, and perfluoromethyl vinyl ether; the second stage mixed monomers include a sulfur point monomer, tetrafluoroethylene, perfluoromethyl vinyl ether, and perfluorooxazine vinyl ether. In step (3), before adding the second stage mixed monomer, the initial mixed monomer is introduced to the pressure of step (3).

2. The method for preparing the perfluoroether raw rubber latex as described in claim 1, characterized in that, It meets one or more of the following conditions: (1) In step (1), a portion of the initial mixed monomer is first introduced into the reaction system to make the oxygen content in the reaction system less than 30~35 ppm. After the temperature is controlled to the reaction temperature, the initial mixed monomer is introduced to the pressure of step (1). (2) In step (2), the first-stage mixed monomers are added until the cumulative polymerization reaction reaches 27-55% of the final yield; (3) The reaction time of step (2) is 1.5 to 4.5 hours; (4) The reaction time of step (3) is 3.5 to 6 hours; (5) The pressure in step (1) is 2.4~2.6 MPa; (6) When the pressure drop in step (1) is 0.2 MPa, proceed to step (2); (7) The pressure in step (2) is 2.4~2.6 MPa; (8) In step (2), the first-stage mixed monomer is added back to the original pressure for every 0.2 MPa decrease in the pressure of the reaction system; (9) The pressure in step (3) is 2.7~2.9 MPa; (10) In step (3), the pressure of the reactor system is maintained by continuously introducing the second-stage mixed monomers; (11) The molar ratio of tetrafluoroethylene and perfluoromethyl vinyl ether in the initial mixed monomer is (40-55):(45-60); (12) The sulfidation point monomer is a sulfidation point monomer containing a cyano group; (13) The perfluorooxoalkyl vinyl ether is formed by one, two or three C atoms. 1-6 Perfluoroalkoxy-substituted perfluoroalkyl vinyl ethers; (14) The molar ratio of tetrafluoroethylene, perfluoromethyl vinyl ether and sulfidation point monomer in the first stage mixed monomer is (50-75):(25-40):(1-2); (15) The molar ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, perfluorooxane vinyl ether and sulfide point monomer in the second stage mixed monomer is (50-75):(15-25):(5-25):(1-2); (16) The initiator is a persulfate; (17) In step (1), the mass ratio of the amount of the initiator added to the water medium is (0.05~0.3)∶100; (18) The initiator is added in batches after the polymerization reaction begins; (19) The chain transfer agent is an iodine-containing fluoroalkane I (CF2). n I, where n = 2 to 7; (20) The mass ratio of the chain transfer agent to the water medium is (0.05~0.3)∶100; (21) The emulsifier is a mixture of perfluoropolyether peroxide and sodium octyl sulfonate; (22) The mass ratio of the emulsifier to the water medium is (0.01~0.3)∶100; (23) A pH adjuster is also added to the polymerization reaction system; (24) The amount of perfluoroether raw rubber formed by the polymerization reaction is in the range of 25 to 55 parts by weight per 100 parts by weight of the aqueous medium; (25) The polymerization reaction is carried out under mechanical stirring; (26) The polymerization reaction temperature is 65–90 °C. o C; (27) The polymerization reaction is carried out in a reactor, and the space left after the water medium is added to the reactor is a vapor space where gaseous monomers exist.

3. The method for preparing the perfluoroether raw rubber latex as described in claim 2, characterized in that, It meets one or more of the following conditions: (1) In step (2), the first-stage mixed monomers are added until the cumulative polymerization reaction reaches 40-53% of the final yield; (2) The reaction time of step (2) is 2 to 4 hours; (3) The reaction time of step (3) is 4.5 to 5.5 hours. (4) The pressure in step (1) is 2.5 or 2.6 MPa; (5) The pressure in step (2) is 2.5 or 2.6 MPa; (6) The pressure in step (3) is 2.7 or 2.8 MPa; (7) The molar ratio of tetrafluoroethylene and perfluoromethyl vinyl ether in the initial mixed monomer is 40:60, 45:55, 50:50 or 55:45; (8) In step (3), before adding the second stage mixed monomer, the initial mixed monomer is introduced to the pressure of step (3), and the initiator is added. The mass ratio of the added initiator to the water medium is (0.03~0.2)∶100; (9) The cyano-containing sulfidation point monomer is selected from CF2=CF-OR. f1 -OR f2 -CN or one or more combinations, R f1 and R f2 Independently for perfluorinated C 2-10 Alkylene; (10) The perfluorooxoalkyl vinyl ether is a perfluoromethoxypropyl vinyl ether; (11) The molar ratio of tetrafluoroethylene, perfluoromethyl vinyl ether and sulfur point monomer in the first stage mixed monomer is 61:38:1, 65:34:1, 70:28:2 or 70:29:1; (12) The molar ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, perfluorooxane vinyl ether and sulfur point monomer in the second stage mixed monomer is 61:18:20:1, 65:20:14:1, 70:18:10:2 or 70:20:9:1; (13) The initiator is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate; (14) In step (1), the mass ratio of the amount of the initiator added to the water medium is (0.1~0.15)∶100; (15) After the polymerization reaction begins, the initiator is replenished every 15 to 30 minutes in steps (2) and (3); (16) The chain transfer agent is one or more selected from perfluoro1,2-diiodoethane, 1,4-perfluorobutyldiiodo, 1,5-perfluoropentyldiiodo, and 1,6-perfluorohexyldiiodo. (17) The mass ratio of the chain transfer agent to the water medium is (0.1-0.2) : 100; (18) The emulsifier is perfluoropolyether peroxide and sodium octyl sulfonate in a mass ratio of 1:1; (19) The mass ratio of the emulsifier added to the water medium is (0.02~0.05)∶100; (20) The pH adjuster is selected from one or more combinations of ammonium carbonate, ammonium bicarbonate, dipotassium hydrogen phosphate and disodium hydrogen phosphate; (21) The amount of perfluoroether raw rubber formed by the polymerization reaction is 30 to 40 parts by weight per 100 parts by weight of the aqueous medium. (22) The stirring speed of the mechanical stirring is 500-900 rpm; (23) The polymerization reaction temperature is 80-85°C. o C; (24) The steam space is 30-50% of the volume of the reactor.

4. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, It meets one or more of the following conditions: (1) In step (2), the first-stage mixed monomers are added until the polymerization reaction accumulates to 44-49% of the final yield. (2) The reaction time of step (2) is 2.8 to 3.2 hours; (3) The reaction time for step (3) is 5 hours; (4) In step (3), before adding the second stage mixed monomer, the initial mixed monomer is introduced to the pressure of step (3), and the initiator is added. The mass ratio of the added initiator to the water medium is (0.06~0.15)∶100. (5) The cyano-containing sulfur point monomer is selected from CF2=CF-OR f1 -OR f2 -CN or one or more combinations, R f1 and R f2 Independently for perfluorinated C 2-6 Alkylene; (6) In step (1), the mass ratio of the amount of initiator added to the mass of the water medium is 0.1:100; (7) After the polymerization reaction begins, initiator is added every 20-25 minutes in steps (2) and (3); (8) The chain transfer agent is 1,6-perfluorohexyl diiodide; (9) The mass ratio of the chain transfer agent to the water medium is 0.1:100, 0.13:100, or 0.2:100; (10) The perfluoropolyether peroxide is ; (11) The mass ratio of the emulsifier to the water medium is 0.02:100, 0.07:300, 0.08:300 or 0.03:100; (12) The pH adjuster is disodium hydrogen phosphate; (13) The mass ratio of the pH adjuster to the water medium is (0.05~1)∶100; (14) The stirring speed of the mechanical stirring is 600-800 rpm; (15) The polymerization reaction is carried out at a temperature of 80°C or 85°C; (16) The steam space is 40% of the volume of the reactor.

5. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, It meets one or more of the following conditions: (1) In step (2), the first-stage mixed monomers are added until the cumulative reaction of the polymerization reaction reaches 46% to 48% of the final yield; (2) The reaction time for step (2) is 3 hours; (3) In step (3), before adding the second stage mixed monomer, the initial mixed monomer is introduced to the pressure of step (3), and the initiator is added. The mass ratio of the added initiator to the water medium is 0.2:300, 0.3:300 or 0.4:

300. (4) The cyano-containing sulfide point monomer is perfluorinated (8-cyano-5-methyl-3,6-dioxa-1-octene); (5) After the polymerization reaction begins, initiator is added every 20-25 minutes in steps (2) and (3); the mass ratio of the amount of initiator added each time to the mass of the water medium is (0.01-0.1):100; (6) The mass ratio of the pH adjuster to the water medium is (0.1-0.15):100; (7) The mechanical stirring speed is 700 rpm.

6. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, It meets one or two of the following conditions: (1) In step (2), the first-stage mixed monomers are added until the polymerization reaction accumulates to 47% or 48% of the final yield; (2) After the polymerization reaction begins, the initiator is added every 20-25 minutes in steps (2) and (3); the mass ratio of the amount of initiator added each time to the mass of the water medium is (0.03-0.05):

100.

7. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, After the polymerization reaction begins, initiator is added every 20-25 minutes in steps (2) and (3); the mass ratio of the amount of initiator added each time to the mass of the water medium is 0.1:300 or 0.15:

300.

8. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, Step (1) includes the following steps: In the presence of the aqueous medium, the initial mixed monomers are heated to 65-90 °C, and then the chain transfer agent, the initiator, and the emulsifier are added.

9. The method for preparing the perfluoroether raw rubber latex as described in claim 3, characterized in that, Step (1) includes the following steps: In the presence of the aqueous medium, the initial mixed monomers are heated to 80 °C, and then the chain transfer agent, the initiator, and the emulsifier are added.

10. The method for preparing the perfluoroether raw rubber latex as described in claim 1, characterized in that, The preparation method includes the following specific steps: (1) In the presence of the aqueous medium, a portion of the initial mixed monomers is introduced into the reaction system to replace the air, mechanical stirring is performed, and the mixture is heated until the temperature of the reaction solution stabilizes at 80-85°C. o After step C, the initial mixed monomers are introduced to bring the pressure of the reaction system to 2.4~2.6 MPa. Then, the first batch of initiator is added to initiate the polymerization reaction. Subsequently, emulsifier, pH adjuster and chain transfer agent are added. The mass ratio of the first batch of initiator to the water medium is (0.1~0.15):

100. (2) For every 0.2 MPa decrease in the reaction system pressure, the first-stage mixed monomers are added to maintain the reaction system pressure at 2.4~2.6 MPa until the polymerization reaction accumulates to 44~48% of the final yield. During this process, the initiator is added in batches every 20~25 minutes, and the mass ratio of the amount of initiator added each time to the water medium is (0.03~0.05):100; to maintain the polymerization reaction. (3) The initial mixed monomers are introduced again to make the reaction pressure reach 2.7~2.9 MPa, and the second batch of initiator is added. The mass ratio of the second batch of initiator to the water medium is (0.06~0.1):

100. Polymerization is carried out. For every 0.2 MPa decrease in the reaction system pressure, the second stage mixed monomers are added to maintain the reaction system pressure at 2.7~2.9 MPa. During this process, the initiator is added in batches every 20~25 minutes. The mass ratio of the initiator added each time to the water medium is (0.03~0.05):

100. The polymerization reaction is maintained until the final yield is obtained to prepare the perfluoroether raw rubber latex.

11. A perfluoroether raw rubber latex, characterized in that, It is prepared by the preparation method according to any one of claims 1-10.

12. A perfluoroether raw rubber, characterized in that, It is prepared by coagulating, washing, and vacuum drying the perfluoroether raw rubber emulsion as described in claim 11.

13. The perfluoroether raw rubber as described in claim 12, characterized in that, It meets one or more of the following conditions; (1) The emulsion is coagulated using magnesium chloride; (2) The vacuum drying temperature is 85-110℃. o C; (3) The perfluoroether raw rubber has a fluorine content of 68% or more.

14. The perfluoroether raw rubber as described in claim 12, characterized in that, It meets one or more of the following conditions; (1) The emulsion is coagulated using 5%wt magnesium chloride; (2) The vacuum drying temperature is 95°C. o C; (3) The perfluoroether raw rubber has a fluorine content of 72% or more.

15. The application of the perfluoroether raw rubber as described in claim 12 in the preparation of rubber.

16. A vulcanized rubber, characterized in that, It is obtained by vulcanizing the perfluoroether raw rubber as described in claim 12.

17. The vulcanized rubber as described in claim 16, characterized in that... The vulcanization process includes the following steps: the perfluoroether raw rubber is mixed with bis(2,5) vulcanizate, TAIC and carbon black N990, and then vulcanized in stages. The first stage of vulcanization is carried out under vulcanization conditions of 170~190°C. o C×10min, pressure 10~15 MPa; two-stage vulcanization: vulcanization conditions 220~240 o The vulcanized rubber is prepared by heating for 4 hours (C×4 h).

18. The vulcanized rubber as described in claim 17, characterized in that, It meets one or more of the following conditions: (1) The mixing process includes the following steps: first, the perfluoroether raw rubber is mixed with bis(2,5)-5-vinyl chloride, TAIC and carbon black N990 until there is no obvious difference in the rubber compound, and then the mixture is thinly mixed 8 to 12 times in the form of triangular bags; (2) The mixing temperature shall not exceed 60℃; (3) The vulcanization conditions for the first stage are 177 o C×10 min, pressure 10~15 MPa; (4) The conditions for the two-stage vulcanization are 230°C. o C×4 h.

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