Perfluoroether raw rubber resistant to low temperature and strong oxidizing medium as well as preparation method and application of perfluoroether raw rubber

Abstract

The invention provides low-temperature-resistant and strong-oxidizing-medium perfluoroether raw rubber as well as a preparation method and application of the low-temperature-resistant and strong-oxidizing-medium perfluoroether raw rubber. The preparation method of the elastomer comprises the following steps: carrying out polymerization reaction on tetrafluoroethylene and a mixture of water, perfluoromethoxy methyl vinyl ether, an emulsifier, a chain transfer agent, an initiator and a vulcanization point monomer to obtain the elastomer, wherein the tetrafluoroethylene is added in the form of gas, and a polymerization reaction is carried out under 2-5 Mpa; the mass ratio of the perfluoromethoxy methyl vinyl ether to the emulsifying agent is 1: (0.01-0.1); the mass ratio of the perfluoromethoxy methyl vinyl ether to the chain transfer agent is 2: (0.01-0.1); the mass ratio of the perfluoromethoxy methyl vinyl ether to the vulcanization point monomer is 2: (0.01-0.2). The preparation method provided by the invention can be used for efficiently preparing the elastomer, and the obtained elastomer is resistant to low temperature, good in mechanical property and good in processability.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine-containing materials, and in particular relates to a low-temperature and strong oxidizing medium resistant perfluoroether raw rubber, and a preparation method and application thereof. Background Art

[0002] Perfluoroether elastomer was first successfully developed by DuPont in the United States in 1968. It is an elastomer that does not contain CH bonds at all. It is mainly made of tetrafluoroethylene and perfluoroalkyl vinyl ether as monomers, and copolymerized with cyanide-containing perfluoroolefins, (perfluoro)phenoxy olefins, bromine-containing perfluoroolefins, and iodine-containing perfluoroolefins as vulcanization point monomers. As the name indicates, perfluoroether elastomers have all hydrogen atoms on all carbon atoms in the polymer replaced by fluorine atoms, and are resistant to more than 1,600 known solvents.

[0003] Zhonghao Chenguang Chemical Research Institute Co., Ltd. has already carried out research and development of low-temperature resistant (-40°C) parafluoroether rubber. After that, the company further cooperated with other institutions to carry out engineering research on -30°C parafluoroether rubber.

[0004] Among the emulsifiers currently used, ammonium perfluorooctanoate and its derivative salts are the main ones. Such emulsifiers are difficult to decompose in nature and are harmful to the human body. Therefore, the use of such emulsifiers has been gradually banned internationally. Our goal is to develop an emulsification system that is easy to decompose and harmless to the human body.

[0005] The patent application with publication number CN106317290A discloses a method for preparing a perfluoroether elastomer and the obtained perfluoroether elastomer. However, the patent application points out that the perfluoroether elastomer itself has a high hardness, so it is difficult to process and refining. However, the patent application does not mention the low temperature performance of the perfluoroether elastomer.

[0006] A low-temperature resistant perfluoroether rubber composition, publication number CN112457612A, and its preparation method and application, can improve the low-temperature resistance of perfluoroether rubber without affecting other properties of the rubber composition by synergizing liquid fluoroelastomer with perfluoroether rubber. However, it relies on special liquid fluoroelastomer, which is not conducive to mass production.

[0007] Therefore, it is necessary to study and improve the current preparation of perfluoroether elastomers to obtain perfluoroether elastomers with better performance in order to expand the promotion and application of perfluoroether rubber. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defect of poor low temperature resistance of elastomers. To this end, the present invention provides a low temperature and strong oxidizing medium resistant perfluoroether rubber, a preparation method and application thereof. The elastomer provided by the present invention has good low temperature resistance and good application prospects.

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

[0010] The present invention provides a method for preparing an elastomer, which comprises the following steps:

[0011] A mixture of water, perfluoromethoxymethyl vinyl ether, an emulsifier, a chain transfer agent, an initiator and a vulcanization point monomer is polymerized with tetrafluoroethylene to obtain an elastomer;

[0012] Wherein, the tetrafluoroethylene is added in the form of gas and the polymerization reaction is carried out at 2-5Mpa;

[0013] The mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 1: (0.01-0.1);

[0014] The mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2: (0.01-0.1);

[0015] The mass ratio of the perfluoromethoxymethyl vinyl ether to the vulcanization site monomer is 2:(0.01-0.2);

[0016] The vulcanization site monomer is , where Y is a perfluorocarbon 1-6 Alkyl or perfluorinated C 1-6 Ether group; X is halogen;

[0017] The perfluoromethoxymethyl vinyl ether is CF3OCF2OCF=CF2;

[0018] The emulsifier is WOQ-COONH4, W and Q are independently perfluorocarbons. 1-6 alkyl.

[0019] In one embodiment, the water is deionized water.

[0020] In one embodiment, the chain transfer agent is I(CF2) n I, n is 2-7, and the chain transfer agent can be selected from a combination of one or more of perfluoro-1,2-diiodoethane, perfluoro-butyl-diiodide, perfluoro-pentyl-diiodide, and perfluoro-hexyl-diiodide, for example, perfluoro-1,2-diiodoethane.

[0021] In one embodiment, the initiator is a persulfate and / or a thiosulfate, which can be selected from a combination of one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and sodium thiosulfate, such as potassium persulfate. The initiator is used in the form of an aqueous solution, and the addition method can be one-time addition, batch addition, or continuous addition. For example, the initiator is added at any time after the polymerization reaction starts in the form of an aqueous solution. The initiator can be added to the reaction system multiple times to better play its role.

[0022] In one embodiment, the emulsifier comprises a perfluorocarbon 1-6 The alkyl group is a perfluorinated C 1-3 Alkyl, such as CF3CF2- or -CF2-.

[0023] In one embodiment, the emulsifier is WO-CF2-COONH4, W is a perfluorocarbon 1-3 Alkyl, such as CF3CF2OCF2COONH4 and / or CF3(CF3)CFOCF2COONH4. The emulsifier can be added all at once, in batches or continuously.

[0024] In one embodiment, halogen is fluorine, chlorine, bromine or iodine.

[0025] In one embodiment, the sulfurization site monomer is a perfluorocarbon. 1-6 The alkyl group is a perfluorinated C 2-3 Alkyl, such as -CF2CF2-, -CF2CF2CF2- or -CF(CF3)CF2-, preferably -CF2CF2-.

[0026] In one embodiment, in the vulcanization site monomer, Y is a perfluorocarbon. 1-6 Preferably, the sulfurization site monomer is a combination of two monomers, one of which has a linear C 2-3 Alkyl, another monomer species Y is a branched C 2-3 alkyl.

[0027] In one embodiment, in the vulcanization site monomer, the perfluorocarbon 1-6 The ether group is -C 1-3 Alkyl-OC 1-3 Alkyl, for example -CF2CF2-O-CF2CF2-.

[0028] In one embodiment, the vulcanization site monomer is selected from , , , , , , and A combination of one or more (e.g., 2) of , or and (Further preferred and The mass ratio is 1:1).

[0029] In one embodiment, the vulcanization site monomer is and (Preferred and The mass ratio is 1:1). and (The preferred mass ratio of the two is 1:1), and (Preferably the mass ratio of the two is 1:1) or and (The preferred mass ratio of the two is 1:1).

[0030] In one embodiment, the mass ratio of the water to the perfluoromethoxymethyl vinyl ether is (5-20):1, such as 15:1 or 10:1.

[0031] In one embodiment, the mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 1:(0.03-0.08), for example, 2:0.1.

[0032] In one embodiment, the mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2:(0.03-0.08), for example, 2:0.05.

[0033] In one embodiment, the mass ratio of the perfluoromethoxymethyl vinyl ether to the vulcanization site monomer is 2:(0.1-0.15); for example, 2:0.12.

[0034] In one embodiment, the mass ratio of the perfluoromethoxymethyl vinyl ether to the initiator is 1:(0.01-1); preferably 1:(0.01-0.1), for example 1:0.04.

[0035] In one embodiment, the initiator is used in the form of an aqueous solution, and the mass ratio of the initiator (e.g., potassium persulfate) to water is (0.01-1):1, preferably (0.04-0.1):1, such as 0.08:1. The initiator can be added in multiple times, preferably 5-20 v% is added for the first time, such as 15 v%, and the rest is continuously added, where v is the volume ratio of the added portion to the total.

[0036] In one embodiment, the polymerization reaction is carried out at 75-90°C, for example, 80-90°C or 75-85°C.

[0037] In one embodiment, the tetrafluoroethylene is added to the polymerization reaction via a passage so that tetrafluoroethylene gas can be added at any time, preferably a steel passage.

[0038] In one embodiment, the polymerization pressure is controlled by adding tetrafluoroethylene gas.

[0039] In one embodiment, the polymerization reaction is carried out at 2.2-4 MPa, such as 3.2-4 MPa, preferably 4 MPa or 3.2 MPa.

[0040] In one embodiment, the polymerization reaction temperature is 75-90°C, such as 80°C.

[0041] In one embodiment, the polymerization reaction comprises the following post-treatment steps: after the reaction is completed, drying (e.g., drying at 100°C, preferably vacuum drying), washing (e.g., washing with an amide solvent, an alcohol solvent, and washing with water, the amide solvent being, for example, N,N-dimethylformamide, the alcohol solvent being, for example, ethanol, and the water being, for example, deionized water), and drying (e.g., drying at 120°C, preferably vacuum drying).

[0042] In one embodiment, in the product obtained by the polymerization reaction, the elastomer content is 5-30%, such as 5-15% or 10-30%, where the percentage (%) refers to the mass part of the copolymer per 100 parts by weight of the aqueous medium.

[0043] In one embodiment, the polymerization reaction comprises the following steps: mixing the water and the perfluoromethoxymethyl vinyl ether, adding the emulsifier, the chain transfer agent, the initiator and the vulcanization site monomer to obtain a mixed solution, adding the initiator (for example, adding an aqueous solution of the initiator), preferably, first adding part of the initiator (for example, adding 5-20 v%, preferably 15 v%, and the remaining part is continuously replenished, v% is the volume percentage of the first added initiator to the total initiator), and / or first adding part of the mixed solution (for example, adding 5-20 wt% for the first time, preferably 15 wt%, and the remaining part is continuously replenished, wt% is the mass percentage of the first added mixed solution to the total mixed solution); adding tetrafluoroethylene, and performing a polymerization reaction at 2-5Mpa to obtain the elastomer. Further preferably, during the polymerization reaction, the mixed solution, tetrafluoroethylene and the initiator are continuously replenished (preferably the replenishment rate ratio is 1000: (30-80), for example 1000: 50 or 1000: 66), and the elastomer is prepared by continuous flow.

[0044] In one embodiment, the polymerization reaction is carried out in a tubular reactor, which is conventional in the art and can be selected by a person skilled in the art as needed, as long as it does not affect the reaction. Preferably, the tubular reactor has a specification of 2500 mm*100 mm. The tubular reactor can be made of conventional materials in the art, such as stainless steel.

[0045] In one embodiment, the preparation method comprises the following steps:

[0046] Step (1): mixing the emulsifier, the perfluoromethoxymethyl vinyl ether (MOVE monomer), the sulfide monomer, the chain transfer agent and the water to obtain a mixed solution, and adding the mixed solution to the tubular reactor (for example, adding 5-20%, preferably 15%, wt% is the mass percentage of the mixed solution added first to the total mixed solution, and the remaining part is continuously added);

[0047] Step (2): adding an initiator (e.g., an aqueous solution of the initiator, preferably 5-20 v % is added first, and 15 v % can be added, where v % is the mass percentage of the portion added first, and the remaining portion is added continuously), adding tetrafluoroethylene, the reaction pressure is 2-5 MPa, the reaction temperature is 75-90° C., and the polymerization reaction is carried out.

[0048] In one embodiment, the polymerization reaction is carried out continuously, and the residence time of the polymerization reaction can be 5-15 hours, preferably 10 hours.

[0049] In one embodiment, the tetrafluoroethylene is added in the form of gas, and the reaction pressure is preferably 4 MPa.

[0050] In one embodiment, the mixed liquid is added into the tubular reactor at a rate of 0.5-10 L / h, preferably 1 L / h or 5 L / h.

[0051] In one embodiment, the initiator is used in the form of an aqueous solution, and the aqueous solution is added to the tubular reactor at a rate of 30-80 mL / h, preferably 66 mL / h.

[0052] In one embodiment, the initiator is added in the form of an aqueous solution, preferably at a rate of 10-500 mL / h, such as 50 mL / h, 66 mL / h or 100 mL / h. Preferably, the mass ratio of the initiator (based on the mass of the initiator) to the perfluoromethoxymethyl vinyl ether is (1-6):100, such as 4:100.

[0053] Preferably, the effect of continuous reaction is achieved by maintaining a balance between feed and discharge, and the discharge rate can be adjusted according to the reaction scale, for example, 0.5-10 L / h, preferably 1 L / h or 5 L / h.

[0054] In one embodiment, the initiator is used in the form of an aqueous solution, and the addition rate is preferably 0.001-0.006 Kg / h Kg / h, for example 0.004 Kg / h or 0.0053 Kg / h, based on the mass of the initiator.

[0055] In one embodiment, the addition rate of the perfluoromethoxymethyl vinyl ether is 0.03-0.1 Kg / h, for example, 0.06 Kg / h.

[0056] In one embodiment, the preparation method comprises the following steps:

[0057] (1) mixing the perfluoromethoxymethyl vinyl ether with the water, adding the emulsifier (e.g., CF3CF2OCF2COONH4 and / or CF3(CF3)CFOCF2COONH4), the chain transfer agent (e.g., perfluoro-1,2-diiodoethane), and the vulcanization site monomer combination; and (preferably the mass ratio is 1:1) to obtain a mixed solution; first add 5-20 wt% to the tubular reactor, for example 15 wt%, wt being the mass ratio of the first added part to the whole;

[0058] (2) adding a portion (e.g., 5-20 v%, preferably 15 v%, where v is the volume ratio of the portion added first to the total volume) of the initiator aqueous solution into the tubular reactor;

[0059] (3) Inject TFE into the tubular reactor to a pressure of 4 MPa and maintain the reaction temperature at 75-90°C;

[0060] (4) The reaction residence time is 10 h, the material is discharged, and the mixed solution (e.g., 1 L / h) and the initiator aqueous solution (e.g., 50 or 66 mL / h) are continuously added at the same time;

[0061] (5) The obtained liquid is dried (for example, at 100° C. for 8 h), washed (for example, rinsed three times with DMF, rinsed once with ethanol, and rinsed three times with deionized water), and dried (for example, at 120° C. for 10 h) to obtain the elastomer.

[0062] In the present invention, the polymerization pressure can be controlled to be 2.0-3.0MPa, preferably 2.2-2.5MPa, in the early stage of the polymerization reaction (i.e., before the polymerization reaction accumulates to 70-80% of the final output); the polymerization pressure in the late stage of the polymerization reaction (i.e., after the polymerization reaction accumulates to 70-80% of the final output) is 3.0-5.0MPa, preferably 3.5-4.0MPa. The required polymerization pressure is initially achieved by adjusting the amount of gaseous monomers in the initial feed, and after the reaction starts, the pressure is adjusted by controlling the stage increment feed of the gaseous monomers. The polymerization pressure is set within the above range, because if the pressure is lower than 2.0MPa, the concentration of monomers other than tetrafluoroethylene in the polymerization reaction system is too low, the reaction activity is also low, and a satisfactory reaction rate cannot be achieved; if the reaction rate is slow, demulsification is also likely to occur, resulting in wall sticking and increasing the maintenance cost of the reactor. If the pressure is higher than 4.0MPa, the amount of monomers liquefied in the reactor increases, thereby not only increasing the amount of monomers consumed, but also making the conversion rate low, increasing the material cost. In addition, if the pressure is higher than 4.0MPa, higher requirements will be placed on equipment, systems and pipelines, increasing production costs.

[0063] During the polymerization process, the polymerization rate can be stabilized by adjusting the polymerization temperature. During the polymerization reaction, the reaction temperature is maintained between 75 and 90°C according to the pressure of different reaction processes, preferably (80-90) and (75-85)°C. If the temperature is lower than 75°C, the copolymerization rate is too slow and is not suitable for effective production on an industrial scale. However, if the temperature is higher than 90°C, the initiator decomposes quickly, which will cause a waste of initiator; the rapid decomposition of the initiator will also lead to a fast polymerization reaction rate, the reaction process is difficult to control, and the segment structure of the polymer cannot be effectively controlled, resulting in an excessively high content of tetrafluoroethylene in the polymer, high stiffness of the elastomer, and high hardness. At the same time, high reaction temperature will also cause wall formation inside the reactor, thereby affecting product quality and increasing labor costs. Therefore, the reaction temperature must be controlled within an effective range.

[0064] The present invention controls the polymerization speed by controlling the polymerization pressure and temperature and by adding the initiator amount. Usually, the present invention can realize continuous feeding reaction and usually does not need to stop the machine for feeding.

[0065] The present invention provides an elastomer obtained by the above preparation method.

[0066] The present invention provides an application of the above-mentioned elastomer, the applications including: (1) for preparing low-temperature resistant rubber products; and / or (2) low-temperature resistant seals, the seals being used, for example, for downhole tool seals, wellhead equipment seals, pipeline valve seals, pump and compressor seals in the oil and gas industry.

[0067] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0068] The reagents and raw materials used in the present invention are commercially available.

[0069] The positive progress of the present invention is that the preparation process of the present invention and the obtained elastomer have one or more of the following advantages:

[0070] (1) Elastomers have good low temperature resistance, good plasticity and good processability.

[0071] (2) The perfluoroether elastomer synthesized in the present invention has the advantages of fast vulcanization speed, low temperature resistance, high tensile strength and low compression deformation.

[0072] (3) The perfluoroether elastomer prepared by the present invention has better elasticity than conventional perfluoroether elastomer rubber, and is easier to coat during secondary processing on an open mill, thereby improving processing efficiency. Compared with the perfluoroether elastomer obtained by emulsion polymerization using the same formula and direct mixing, the perfluoroether elastomer prepared by the present invention has a lower hardness of fluororubber after vulcanization and a higher filler filling rate. Since perfluoroether elastomers are expensive, a higher filler filling rate can significantly reduce costs for downstream users, thereby expanding the promotion and application of perfluoroether rubber. DETAILED DESCRIPTION

[0073] The technical solution of the present invention is further described below through specific implementation methods. Those skilled in the art should understand that the specific implementation methods are only to help understand the present invention and should not be regarded as specific limitations of the present invention. 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.

[0074] In the present invention, the Mooney viscosity is measured by the following method:

[0075] Measured by Mooney viscometer, implementation standards: ISO289 GB / T1232 standard; HGT 3242-2005 Rubber Mooney viscometer technical conditions.

[0076] Tg was measured by differential scanning calorimetry (DSC).

[0077] The fluorine content was measured by elemental analysis using an elemental analyzer (ELementar EL Cube).

[0078] Embodiment 1:

[0079] This embodiment provides a perfluoroether elastomer emulsion, and the specific preparation method is as follows:

[0080] 1) Use nitrogen to purge the pipeline reactor (2500mm*100mm) for 0.5h, then mix 2kg of MOVE monomer (CF3OCF2OCF=CF2) with 30kg of deionized water, stir for 0.5h, add 0.1kg of perfluoroether emulsifier A (CF3CF2OCF2COONH4), 0.05kg of perfluoro 1,2-diiodoethane, and the vulcanization point monomer combination and 0.12kg (mass ratio is 1:1), stirred for 1h to obtain a white emulsion, bubbled with nitrogen for 1h, and partially injected into the pipeline reactor after the bubbles on the surface disappeared (first add 5kg of this white emulsion). 0.08kg of potassium persulfate and 1kg of deionized water were prepared into a solution, 150mL of this solution was added to the reactor, and the rest was added to the injector. After the reaction started, it was injected into the pipeline reactor at a flow rate of 66ml / h.

[0081] 2) Open the TFE valve and inject TFE into the pipeline reactor to a pressure of 4 MPa. Connect the TFE recovery device to keep the TFE in the reactor in a continuous bubbling state. Start the pipeline reactor to start polymerization and maintain the reaction temperature at 75-90 °C.

[0082] 3) Start discharging after 10 hours, maintain TFE pressure, and continue to inject monomer emulsion and initiator solution. Open the discharge port to discharge at a flow rate of 1000ml / h while ensuring that the feed rate matches. Stop feeding after 25 hours, and continue discharging at a flow rate of 1000ml / h until the pipeline reactor is emptied, clean the reactor, and purge with nitrogen for 0.5h.

[0083] 4) The obtained liquid was dried at 100°C for 8 hours, placed on a 100-mesh filter, rinsed three times with DMF, rinsed once with ethanol, rinsed three times with deionized water, and dried at 120°C for 10 hours. 2.6 kg of white solid was obtained.

[0084] Embodiment 2:

[0085] This embodiment provides a perfluoroether elastomer emulsion, and the specific preparation method is as follows:

[0086] 1) Use nitrogen to purge the pipeline reactor (same as Example 1) for 0.5h, then mix 2kg of MOVE monomer (CF3OCF2OCF=CF2) with 30kg of deionized water, stir for 0.5h, add 0.1kg of perfluoro emulsifier A (CF3CF2OCF2COONH4) and B (CF3(CF3)CFOCF2COONH4) (mass ratio 1:1), 0.05kg of chain transfer agent perfluoro 1,2-diiodoethane, and the vulcanization point monomer combination and 0.12 kg (mass ratio is 1:1), stirred for 1 hour to obtain a white emulsion, bubbled with nitrogen for 1 hour, and after the bubbles on the surface disappeared, part of it (5 kg) was injected into the pipeline reactor.

[0087] 2) Prepare a solution of 0.08 kg potassium persulfate and 1 kg deionized water, add 150 mL of the solution to the reactor, and add the rest to the injector. After the reaction starts, inject it into the pipeline reactor at a flow rate of 66 ml / h.

[0088] 3) Open the TFE valve and inject TFE into the pipeline reactor to a pressure of 4 MPa. Start the pipeline reactor to begin polymerization and maintain the reaction temperature at 80°C.

[0089] 4) Start discharging after 10 hours, maintain TFE pressure, and continue to inject monomer emulsion and initiator solution. Open the discharge port to discharge at a flow rate of 1000 ml / h, while ensuring that the feed rate matches.

[0090] 5) Stop feeding after 25 hours, and continue discharging at a flow rate of 1000 ml / h until the pipeline reactor is emptied. Clean the reactor and purge it with nitrogen for 0.5 hours.

[0091] 6) The obtained liquid was dried at 100°C for 8 hours, placed on a 100-mesh filter, rinsed three times with DMF, once with ethanol, and three times with deionized water, and dried at 120°C for 10 hours. 2.3 kg of white solid was obtained.

[0092] Embodiment 3:

[0093] Referring to the reaction steps of Example 1, the vulcanization point monomers are replaced with the monomers in the following table to obtain an elastomer. The test properties are shown in the following table:

[0094] .

[0095] Comparative Example 1:

[0096] 1) Use nitrogen to purge the pipeline reactor (same as Example 1) for 0.5 h, then mix 2 kg of MOVE monomer (CF3OCF2OCF=CF2) with 30 kg of deionized water, stir for 0.5 h, add 0.1 kg of perfluoroether emulsifier A (CF3CF2OCF2COONH4) and 0.05 kg of perfluoro 1,2-diiodoethane, stir for 1 h to obtain a white emulsion, use nitrogen to bubble for 1 h, and after the bubbles on the surface disappear, inject part of it (first add 5 kg of this white emulsion) into the pipeline reactor.

[0097] 2) Prepare a solution of 0.08 kg potassium persulfate and 1 kg deionized water, add 150 mL of the solution to the reactor, add the rest to the injector, and inject into the pipeline reactor at a flow rate of 66 ml / h.

[0098] 3) Open the TFE valve and inject TFE into the pipeline reactor to a pressure of 4 Mpa. Start the pipeline reactor to start polymerization and maintain the reaction temperature at 75-90°C.

[0099] 4) Start discharging after 10 hours, maintain TFE pressure, and continue to inject monomer emulsion and initiator solution. Open the discharge port to discharge at a flow rate of 1000ml / h, while ensuring that the feed rate matches.

[0100] 5) Stop feeding after 25 hours, and continue discharging at a flow rate of 1000 ml / h until the pipeline reactor is emptied. Clean the reactor and purge it with nitrogen for 0.5 hours.

[0101] 6) The obtained liquid was dried at 100°C for 8 hours, placed on a 100-mesh filter, rinsed three times with DMF, rinsed once with ethanol, rinsed three times with deionized water, and dried at 120°C for 10 hours. 2.4 kg of white solid was obtained.

[0102] Comparative Example 2:

[0103] 1) Use nitrogen to purge the pipeline reactor (same as Example 1) for 0.5 h, then mix 2 kg of MOVE monomer (CF3OCF2OCF=CF2) with 30 kg of deionized water, stir for 0.5 h, add 0.1 kg of ammonium perfluorooctanoate, 0.05 kg of chain transfer agent (perfluoro 1,2-diiodoethane), 0.12 kg of vulcanization point monomer (same as Example 1), stir for 1 h to obtain a white emulsion, use nitrogen to bubble for 1 h, and after the bubbles on the surface disappear, inject part (5 kg) into the pipeline reactor.

[0104] 2) Prepare a solution of 0.08 kg potassium persulfate and 1 kg deionized water, add 150 mL of this solution to the reactor, add the rest to the injector, and inject into the pipeline reactor at a flow rate of 66 ml / h.

[0105] 3) Open the TFE valve and inject TFE into the pipeline reactor to a pressure of 4 Mpa. Start the pipeline reactor to start polymerization and maintain the reaction temperature at 75-90°C.

[0106] 4) Start discharging after 10 hours, maintain TFE pressure, and continue to inject monomer emulsion and initiator solution. Open the discharge port to discharge at a flow rate of 1000ml / h, while ensuring that the feed rate matches.

[0107] 5) Stop feeding after 25 hours, and continue discharging at a flow rate of 1000 ml / h until the pipeline reactor is emptied. Clean the reactor and purge it with nitrogen for 0.5 hours.

[0108] 6) The obtained liquid was dried at 100°C for 8 hours, and then dried at 120°C for 10 hours. 2.9 kg of white solid was obtained.

[0109] The test results of the elastomers obtained in Examples 1-3 and Comparative Examples 1-2 are shown in the following table:

[0110] .

Claims

1. A method for preparing an elastomer, characterized in that: It includes the following steps: A mixture of water, perfluoromethoxymethyl vinyl ether, an emulsifier, a chain transfer agent, an initiator and a vulcanization point monomer is polymerized with tetrafluoroethylene to obtain an elastomer; Wherein, the tetrafluoroethylene is added in the form of gas and the polymerization reaction is carried out at 2-5Mpa; The mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 1: (0.01-0.1); The mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2: (0.01-0.1); The mass ratio of the perfluoromethoxymethyl vinyl ether to the vulcanization site monomer is 2:(0.01-0.2); The vulcanization site monomer is , where Y is a perfluorocarbon 1-6 Alkyl or perfluorinated C 1-6 Ether group; X is halogen; The perfluoromethoxymethyl vinyl ether is CF3OCF2OCF=CF2; The emulsifier is WOQ-COONH4, W and Q are independently perfluorocarbons. 1-6 alkyl.

2. The preparation method according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The water is deionized water; (2) The chain transfer agent is I(CF2) n I, n is 2-7; (3) The initiator is persulfate and / or thiosulfate; (4) The initiator is used in the form of an aqueous solution; (5) The initiator is added all at once, in batches, or continuously; (6) In the emulsifier, the perfluorocarbon 1-6 The alkyl group is a perfluorinated C 1-3 Alkyl, preferably, the emulsifier is WO-CF2-COONH4, W is a perfluoro C 1-3 alkyl; (7) The emulsifier is added all at once, in batches, or continuously; (8) Halogen is fluorine, chlorine, bromine or iodine; (9) In the above-mentioned vulcanization monomer, the perfluorocarbon 1-6 The alkyl group is a perfluorinated C 2-3 alkyl; (10) In the sulfurization site monomer, the perfluorocarbon 1-6 The ether group is -C 1-3 Alkyl-OC 1-3 alkyl; (11) The polymerization reaction is carried out at 75-90°C; (12) The tetrafluoroethylene is added to the polymerization reaction through a passage so that the tetrafluoroethylene gas can be added at any time; (13) Controlling the polymerization reaction pressure by adding tetrafluoroethylene gas; (14) The polymerization reaction is carried out at 2.2-4 MPa.

3. The preparation method according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The chain transfer agent is selected from one or more of perfluoro-1,2-diiodoethane, perfluorobutyl diiodide, perfluoropentyl diiodide and perfluorohexyl diiodide; (2) The initiator is selected from a combination of one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and sodium thiosulfate; (3) The initiator is added in the form of an aqueous solution at any time after the polymerization reaction begins; (4) In the emulsifier, the perfluorocarbon 1-6 Alkyl is CF3CF2- or -CF2-; (5) In the above-mentioned vulcanization point monomer, the perfluorinated C 1-6 Alkyl is -CF2CF2-, -CF2CF2CF2- or -CF(CF3)CF2-; (6) In the sulfurization point monomer, the perfluorocarbon 1-6 The ether group is -CF2CF2-O-CF2CF2-; (7) The polymerization reaction is carried out at 80-90°C or 75-85°C; (8) The tetrafluoroethylene is added to the polymerization reaction through a steel passage; (9) The polymerization reaction is carried out at 3.2-4Mpa.

4. The preparation method according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The chain transfer agent is perfluoro-1,2-diiodoethane; (2) The initiator is potassium persulfate; (3) The emulsifier is CF3CF2OCF2COONH4 and / or CF3(CF3)CFOCF2COONH4; (4) The vulcanization site monomer is selected from , , , , , , and A combination of one or more; preferably , or and ,in and The mass ratio is further preferably 1:1; (5) The polymerization reaction is carried out at 3.2 or 4 MPa; (6) The polymerization reaction is carried out at 80°C.

5. The preparation method according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The mass ratio of the water to the perfluoromethoxymethyl vinyl ether is (5-20):1, for example, 15:1 or 10:1; (2) The mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 1:(0.03-0.08), for example, 2:0.1; (3) The mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2:(0.03-0.08), for example, 2:0.05; (4) The mass ratio of the perfluoromethoxymethyl vinyl ether to the vulcanization site monomer is 2:(0.1-0.15); for example, 2:0.12; (5) The mass ratio of the perfluoromethoxymethyl vinyl ether to the initiator is 1:(0.01-1); preferably 1:(0.01-0.1), for example 1:0.04; (6) The initiator is used in the form of an aqueous solution, and the mass ratio of the initiator to water is (0.01-1):1, preferably (0.04-0.1):1, for example 0.08:1; (7) The initiator is added in multiple times, preferably 5-20 v% is added for the first time, for example 15 v%, and the rest is added continuously, where v is the volume ratio of the added portion to the total; (8) In the product obtained by the polymerization reaction, the elastomer content is 5-30%, such as 5-15% or 10-30%, where the percentage is the mass part of the copolymer per 100 parts by weight of the aqueous medium; (9) The sulfurization point monomer is a combination of two monomers, one of which has a straight chain C 2-3 Alkyl, another monomer species Y is a branched C 2-3 alkyl.

6. The preparation method according to claim 1, characterized in that: The polymerization reaction comprises the following steps: mixing the water and the perfluoromethoxymethyl vinyl ether, adding the emulsifier, the chain transfer agent, the initiator and the vulcanization point monomer to obtain a mixed solution, adding the initiator, preferably, adding part of the initiator first, and / or adding part of the mixed solution first; adding tetrafluoroethylene, and performing a polymerization reaction at 2-5Mpa to obtain the elastomer; Preferably, the polymerization reaction comprises the following post-treatment steps: drying, washing, and drying after the reaction is completed.

7. The preparation method according to claim 1, characterized in that: It includes the following steps: Step (1): mixing the emulsifier, the perfluoromethoxymethyl vinyl ether, the sulfide monomer, the chain transfer agent and the water to obtain a mixed solution, and adding the mixed solution into a tubular reactor; Step (2): adding an initiator and tetrafluoroethylene, the reaction pressure is 2-5 MPa, the reaction temperature is 75-90° C., and the polymerization reaction is carried out; Preferably, the preparation method meets one or more of the following conditions: (1) The tubular reactor has the following specifications: 2500 mm*100 mm; (2) The tubular reactor is made of stainless steel; (3) The polymerization reaction is carried out continuously, and the residence time of the polymerization reaction can be 5-15 hours, preferably 10 hours; (4) The tetrafluoroethylene is added in the form of gas, and the reaction pressure is preferably 4 MPa; (5) The mixed liquid is added into the tubular reactor at a rate of 0.5-10 L / h, preferably 1 L / h or 5 L / h; (6) The initiator is used in the form of an aqueous solution, and the rate of adding the aqueous solution into the tubular reactor is 30-80 mL / h, preferably 66 mL / h; (7) The initiator is added in the form of an aqueous solution, preferably at a rate of 10-500 mL / h, such as 50 mL / h, 66 mL / h or 100 mL / h. Preferably, the mass ratio of the initiator to the perfluoromethoxymethyl vinyl ether is (1-6):100, such as 4:100; (8) The initiator is used in the form of an aqueous solution, and the addition rate is preferably 0.001-0.006 Kg / h Kg / h, for example 0.004 Kg / h or 0.0053 Kg / h, based on the mass of the initiator; (9) The addition rate of the perfluoromethoxymethyl vinyl ether is 0.03-0.1 Kg / h, for example, 0.06 Kg / h; (10) First, 5-20 wt% of the mixed solution is added to the tubular reactor, for example, 15 wt%, where wt is the mass ratio of the first added portion to the total, and the remaining portion is continuously added; (11) The initiator is used in the form of an aqueous solution, preferably 5-20 v % is added first, and 15 v % can be added, where v % is the mass percentage of the first added portion to the total mass, and the remaining portion is continuously added.

8. The preparation method according to any one of claims 1 to 7, characterized in that: It includes the following steps: Step (1): Mix the perfluoromethoxymethyl vinyl ether with the water, and add the emulsifier, the chain transfer agent, and the vulcanization point monomer combination: and obtaining a mixed solution; and adding the mixed solution into the tubular reactor; Step (2): adding a portion of the initiator aqueous solution into the tubular reactor; Step (3): inject TFE into the tubular reactor, control the pressure to 4 MPa, and maintain the reaction temperature at 75-90°C; Step (4): The reaction residence time is 10 hours, the material is discharged, and the mixed solution and the initiator aqueous solution are continuously added at the same time; Step (5): The obtained liquid is dried, washed, and dried to obtain the elastomer.

9. An elastomer, characterized in that: The invention discloses a novel nanostructured carbon foam prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the elastic body according to claim 9, characterized in that: The applications include: (1) for preparing low-temperature resistant rubber products; and / or (2) low-temperature resistant seals.

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