Low-temperature-resistant and strong-oxidizing-medium-resistant perfluoroether raw rubber, preparation method and application thereof

Abstract

The application provides a perfluoroether raw rubber resistant to low temperature and strong oxidizing medium, a preparation method and application thereof. Specifically provided is a preparation method of an elastomer, which comprises the following steps: polymerizing a mixture of water, perfluoromethoxy methyl vinyl ether, an emulsifier, a chain transfer agent, an initiator and a vulcanization point monomer with tetrafluoroethylene to obtain the elastomer; wherein the tetrafluoroethylene is added in a gaseous form, and the polymerization reaction is carried out under 2-5 Mpa; the mass ratio of the perfluoromethoxy methyl vinyl ether to the emulsifier 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); and the mass ratio of the perfluoromethoxy methyl vinyl ether to the vulcanization point monomer is 2:(0.01-0.2). The preparation method can efficiently prepare the elastomer, and the obtained elastomer is resistant to low temperature, has good mechanical properties and good processability.

Description

TECHNICAL FIELD

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

[0002] The perfluoroether elastomer was first developed by the DuPont Company in 1968, and is an elastomer completely free of C-H bonds, mainly composed of tetrafluoroethylene and perfluoroalkyl vinyl ether as monomers, and copolymerized with cyano-containing perfluoroolefin, (perfluoro) phenoxy olefin, bromine-containing perfluoroolefin and iodine-containing perfluoroolefin as vulcanization point monomers. The perfluoroether elastomer, as the name implies, has all the hydrogen atoms on the carbon atoms in the polymer replaced by fluorine atoms, and can resist more than 1600 known solvents.

[0003] Zhonghao Chen Guang Chemical Research Institute Co., Ltd. has carried out the development of low-temperature-resistant (-40℃) perfluoroether rubber. Subsequently, the company further cooperated with other institutions to carry out the engineering research of -30℃ perfluoroether rubber.

[0004] Among the emulsifiers currently used, ammonium perfluorooctanoate and its derivative salts are mainly used. Such emulsifiers are difficult to decompose in nature and are harmful to the human body, and therefore, the use of such emulsifiers has been gradually prohibited internationally. Our requirement is to develop an easily decomposable and harmless emulsion system for the human body.

[0005] Patent application No. CN106317290A discloses a preparation method of perfluoroether elastomer and the obtained perfluoroether elastomer. However, the patent application points out that the perfluoroether elastomer itself has high hardness, and therefore, there are difficulties in processing and refining. However, the patent application does not mention the low-temperature performance of the perfluoroether elastomer.

[0006] Patent application No. CN112457612A discloses a low-temperature-resistant perfluoroether rubber composition, a preparation method and application thereof. By synergistic effect of liquid fluorine elastomer and perfluoroether rubber, the low-temperature resistance of the perfluoroether rubber can be improved without affecting other properties of the rubber composition. However, the special liquid fluorine elastomer is not conducive to mass production.

[0007] Therefore, it is necessary to research and improve the preparation of the perfluoroether elastomer to obtain a perfluoroether elastomer with better performance, so as to expand the popularization and application of the perfluoroether rubber. SUMMARY

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

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

[0010] This invention provides a method for preparing an elastomer, comprising the following steps:

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

[0012] The tetrafluoroethylene is added in gaseous form and undergoes a polymerization reaction at 2-5 MPa.

[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 sulfidation point monomer is 2:(0.01-0.2).

[0016] The sulfurization point monomer is Where Y is a perfluorinated C 1-6 Alkyl or perfluorinated C 1-6 Ether group; X is a halogen;

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

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

[0019] In one particular scheme, 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 one or more combinations of perfluoro1,2-diiodoethane, perfluorobutyldiiodide, perfluoropentyldiiodide, and perfluorohexyldiiodide, such as perfluoro1,2-diiodoethane.

[0021] In one embodiment, the initiator is a persulfate and / or thiosulfate, selected from one or more combinations of potassium persulfate, sodium persulfate, ammonium persulfate, and sodium thiosulfate, such as potassium persulfate. The initiator is used in aqueous solution form, and can be added all at once, in batches, or continuously. For example, the initiator can be added in aqueous solution as needed after the polymerization reaction begins. Multiple additions of the initiator to the reaction system allow for better utilization of its function.

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

[0023] In one embodiment, the emulsifier is WO-CF2-COONH4, where W is a perfluorinated C. 1-3 Alkyl groups, such as CF3CF2OCF2COONH4 and / or CF3(CF3)CFOCF2COONH4. The emulsifier may be added in one batch, in batches, or continuously.

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

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

[0026] In one embodiment, Y in the sulfurization point monomer is a perfluorinated C. 1-6 Alkyl groups, preferably, the sulfidation point monomer is a combination of two monomers, wherein Y in one monomer is a straight-chain C. 2-3 Alkyl groups, another monomer species Y is a branched C. 2-3 alkyl.

[0027] In one embodiment, the perfluorinated C in the sulfurization point monomer... 1-6 The ether group is -C 1-3 Alkyl-OC 1-3 Alkyl groups, such as -CF2CF2-O-CF2CF2-.

[0028] In one embodiment, the sulfurization point monomer is selected from... , , , , , , and A combination of one or more (e.g., two). Preferably. , or and (Further optimization) and (The mass ratio is 1:1).

[0029] In one embodiment, the sulfurization point monomer is and (Preferred) and (mass ratio 1:1) and (Preferably, the mass ratio of the two is 1:1) and (Preferably, the mass ratio of the two is 1:1) or and (Preferably, the mass ratio of the two is 1:1).

[0030] In one embodiment, the mass ratio of water to perfluoromethoxymethyl vinyl ether is (5-20):1, for example, 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 sulfidation point 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, wherein the mass ratio of the initiator (e.g., potassium persulfate) to water is (0.01-1):1, preferably (0.04-0.1):1, for example, 0.08:1. The initiator can be added in multiple portions, preferably with an initial addition of 5-20 v%, for example, 15 v%, and the remainder added continuously, where v is the ratio of the added portion to the total volume.

[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 introduced into the polymerization reaction via a connecting passage to allow for the replenishment of tetrafluoroethylene gas at any time; preferably, a steel passage is used.

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

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

[0040] In one embodiment, the polymerization reaction is carried out at a temperature of 75-90°C, for example, 80°C.

[0041] In one embodiment, the polymerization reaction includes the following post-processing 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 water, wherein the amide solvent is, for example, N,N-dimethylformamide, the alcohol solvent is, for example, ethanol, and the water is, for example, deionized water), and drying (e.g., drying at 120°C, preferably vacuum drying).

[0042] In one embodiment, the elastomer content in the product obtained by the polymerization reaction is 5-30%, for example 5-15% or 10-30%, where the percentage (%) is the mass parts of the copolymer per 100 parts by weight in an 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 sulfurization point monomer to obtain a mixture, adding the initiator (e.g., adding an aqueous solution of the initiator), preferably, adding a portion of the initiator first (e.g., initially adding 5-20 v%, preferably 15 v%, with the remainder added continuously, v% being the volume percentage of the initially added initiator relative to the total initiator), and / or adding a portion of the mixture first (e.g., initially adding 5-20 wt%, preferably 15 wt%, with the remainder added continuously, wt% being the mass percentage of the initially added mixture relative to the total mixture); adding tetrafluoroethylene, and carrying out the polymerization reaction at 2-5 MPa to obtain the elastomer. More preferably, during the polymerization reaction, the mixture, tetrafluoroethylene, and the initiator are continuously replenished (preferably at a replenishment rate ratio of 1000:(30-80), for example 1000:50 or 1000:66), and the elastomer is prepared in a 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 those skilled in the art as needed, as long as it does not affect the reaction. Preferably, the tubular reactor has dimensions of 2500mm * 100mm. The material of the tubular reactor can be conventional in the art, such as stainless steel.

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

[0046] Step (1): Mix the emulsifier, the perfluoromethoxymethyl vinyl ether (MOVE monomer), the sulfidation point monomer, the chain transfer agent and the water to obtain a mixture, and add it to the tubular reactor (for example, add 5-20% first, preferably 15%, wt% is the mass percentage of the mixture added first to the total mixture, and the remaining part is continuously added).

[0047] Step (2): Add initiator (e.g., an aqueous solution of initiator, preferably 5-20 v % initially, or 15 v % initially, v % is the percentage of the total mass of the initially added portion, with the remainder added continuously), add tetrafluoroethylene, the reaction pressure is 2-5 MPa, the reaction temperature is 75-90℃, and carry out the polymerization reaction.

[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 gaseous form, and the preferred reaction pressure is 4 MPa.

[0050] In one embodiment, the mixture is added to 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, which 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 (by mass of the initiator) to the perfluoromethoxymethyl vinyl ether is (1-6):100, for example, 4:100.

[0053] Preferably, the continuous reaction is achieved by maintaining a balance between the feed and discharge. The discharge rate can be adjusted according to the scale of the reaction, 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, based on the mass of the initiator, is preferably 0.001-0.006 kg / h, for example, 0.004 kg / h or 0.0053 kg / h.

[0055] In one embodiment, the perfluoromethoxymethyl vinyl ether is added at a rate of 0.03-0.1 kg / h, for example, 0.06 kg / h.

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

[0057] (1) The perfluoromethoxymethyl vinyl ether is mixed with the water, and the emulsifier (e.g., CF3CF2OCF2COONH4 and / or CF3(CF3)CFOCF2COONH4), the chain transfer agent (e.g., perfluoro1,2-diiodoethane), and the sulfur point monomer combination are added. and (Preferred mass ratio is 1:1) to obtain a mixture; first add 5-20 wt% to the tubular reactor, for example 15 wt%, where wt is the mass ratio of the first addition to the total mass;

[0058] (2) A portion (e.g., 5-20 v%, preferably 15 v%, where v is the volume ratio of the initial portion to the total volume) of the initiator aqueous solution is added to 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℃;

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

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

[0062] In this invention, the polymerization pressure can be controlled at 2.0~3.0 MPa, preferably 2.2~2.5 MPa, in the early stage of the polymerization reaction (i.e., before the polymerization reaction accumulates to 70~80% of the final yield); and at 3.0~5.0 MPa, preferably 3.5~4.0 MPa, in the later stage of the polymerization reaction (i.e., after the polymerization reaction accumulates to 70~80% of the final yield). The required polymerization pressure is initially achieved by adjusting the amount of gaseous monomer in the initial feed. After the reaction begins, the pressure is adjusted by controlling the incremental feeding of gaseous monomer in stages. The polymerization pressure is set within the above range because if the pressure is below 2.0 MPa, the concentration of monomers other than tetrafluoroethylene in the polymerization system is too low, resulting in low reactivity and an unsatisfactory reaction rate. A slow reaction rate also easily leads to demulsification, causing wall adhesion and increasing the maintenance cost of the reactor. If the pressure is above 4.0 MPa, the amount of liquefied monomer in the reactor increases, which not only increases the amount of monomer consumed but also results in a low conversion rate and increased material costs. In addition, if the pressure is higher than 4.0 MPa, the requirements for equipment, systems and pipelines are higher, which increases production costs.

[0063] During polymerization, the polymerization rate can be stabilized by adjusting the polymerization temperature. The reaction temperature is maintained between 75 and 90°C, preferably (80-90) or (75-85)°C, depending on the pressure of different reaction stages. If the temperature is below 75°C, the copolymerization rate is too slow, unsuitable for efficient industrial-scale production. However, if the temperature is above 90°C, the initiator decomposes rapidly, leading to initiator waste. Rapid initiator decomposition also results in a fast polymerization rate, making the reaction process difficult to control and hindering effective control of the polymer's chain structure. This leads to excessively high tetrafluoroethylene content in the polymer, resulting in high elastomer stiffness and hardness. High reaction temperatures also cause buildup on the reactor walls, affecting product quality and increasing labor costs. Therefore, the reaction temperature must be controlled within an effective range.

[0064] This invention controls the polymerization rate by controlling the polymerization pressure and temperature and by adding an initiator dosage. Under normal circumstances, this invention can achieve continuous feeding reaction and usually does not require stopping the machine to feed.

[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 application including: (1) for the preparation of low-temperature resistant rubber products; and / or (2) low-temperature resistant seals, the seals being used, for example, for sealing downhole tools, wellhead equipment, pipeline valves, pumps and compressors in the oil and gas industry.

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

[0068] The reagents and raw materials used in this invention are all commercially available.

[0069] The positive and progressive effects of this invention are as follows: the preparation process and the resulting elastomer of this invention have one or more advantages in the following aspects:

[0070] (1) The elastomer has good low-temperature resistance, good plasticity, and good processability.

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

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

[0073] 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.

[0074] In this invention, the Mooney viscosity is measured using the following method:

[0075] Measurements were taken with a Mooney viscometer, in accordance with the following standards: ISO289 GB / T1232; HGT 3242-2005 Technical Specifications for Rubber Mooney Viscometers.

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

[0077] The fluorine content was determined by elemental analysis using an ELementar EL Cube instrument.

[0078] Example 1:

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

[0080] 1) Purge the pipeline reactor (2500mm*100mm) with nitrogen for 0.5h, then mix 2kg of MOVE monomer (CF3OCF2OCF=CF2) with 30kg of deionized water and stir for 0.5h. Add 0.1kg of perfluoroether emulsifier A (CF3CF2OCF2COONH4), 0.05kg of perfluorinated 1,2-diiodoethane, and the sulfurization point monomer combination. and 0.12 kg (mass ratio 1:1) was stirred for 1 hour to obtain a white emulsion. Nitrogen gas was used for bubbling for 1 hour. After the surface bubbles disappeared, a portion was injected into the tubular reactor (5 kg of this white emulsion was added initially). 0.08 kg of potassium persulfate and 1 kg of deionized water were mixed to prepare a solution. 150 mL of this solution was added to the reactor, and the remainder was added to the injector. After the reaction started, the solution was injected into the tubular reactor at a flow rate of 66 mL / 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 begin polymerization and maintain the reaction temperature at 75-90℃.

[0082] 3) Start discharging after 10 hours, maintaining TFE pressure while continuously injecting monomer emulsion and initiator solution. Open the outlet and discharge at a flow rate of 1000 ml / h while ensuring the feed rate matches. 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 with nitrogen for 0.5 hours.

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

[0084] Example 2:

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

[0086] 1) Purge the pipeline reactor with nitrogen (same as in Example 1) for 0.5 h, then mix 2 kg of MOVE monomer (CF3OCF2OCF=CF2) with 30 kg of deionized water and stir for 0.5 h. Add 0.1 kg of perfluorinated emulsifier A (CF3CF2OCF2COONH4) and B (CF3(CF3)CFOCF2COONH4) (mass ratio 1:1), 0.05 kg of chain transfer agent perfluorinated 1,2-diiodoethane, and the sulfurization point monomer combination. and 0.12 kg (mass ratio 1:1) was stirred for 1 hour to obtain a white emulsion. Nitrogen gas was used to bubble the emulsion for 1 hour. After the surface bubbles disappeared, a portion (5 kg) was injected into the pipeline reactor.

[0087] 2) Prepare a solution by mixing 0.08 kg of potassium persulfate with 1 kg of deionized water. Add 150 mL of this solution to the reactor and add the remainder to the injector. After the reaction starts, inject the solution 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 continuously inject monomer emulsion and initiator solution. Open the outlet and discharge at a flow rate of 1000 ml / h, while ensuring the feed rate is matched.

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

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

[0092] Example 3:

[0093] Following the reaction steps of Example 1, the vulcanization point monomer was replaced with the monomers listed in the table below to obtain the elastomer. Test performance is shown in the table below:

[0094] .

[0095] Comparative Example 1:

[0096] 1) Purge the pipeline reactor with nitrogen (same as in Example 1) for 0.5 h, then mix 2 kg of MOVE monomer (CF3OCF2OCF=CF2) with 30 kg of deionized water and stir for 0.5 h. Add 0.1 kg of perfluoroether emulsifier A (CF3CF2OCF2COONH4) and 0.05 kg of perfluoro1,2-diiodoethane and stir for 1 h to obtain a white emulsion. Bubble the emulsion with nitrogen for 1 h. After the bubbles on the surface disappear, inject a portion (first add 5 kg of this white emulsion) into the pipeline reactor.

[0097] 2) Prepare a solution by mixing 0.08 kg of potassium persulfate with 1 kg of deionized water. Add 150 mL of this solution to the reactor and add the remainder to the injector. Inject the solution 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 begin polymerization and maintain the reaction temperature at 75-90℃.

[0099] 4) Start discharging after 10 hours, maintaining TFE pressure while continuously injecting monomer emulsion and initiator solution. Open the outlet and discharge at a flow rate of 1000 ml / h, while ensuring the feed rate is matched.

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

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

[0102] Comparative Example 2:

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

[0104] 2) Prepare a solution by mixing 0.08 kg of potassium persulfate with 1 kg of deionized water. Add 150 mL of this solution to the reactor and add the remainder to the injector. Inject the solution 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 begin polymerization and maintain the reaction temperature at 75-90℃.

[0106] 4) Start discharging after 10 hours, maintaining TFE pressure while continuously injecting monomer emulsion and initiator solution. Open the outlet and discharge at a flow rate of 1000 ml / h, while ensuring the feed rate is matched.

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

[0108] 6) The resulting liquid was dried at 100℃ for 8 hours, then dried at 120℃ 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 table below:

[0110] .

Claims

1. A method for preparing an elastomer, characterized in that, It includes the following steps: A mixture of water, perfluoromethoxymethyl vinyl ether, emulsifier, chain transfer agent, initiator, and sulfur point monomer is polymerized with tetrafluoroethylene to obtain an elastomer. The tetrafluoroethylene is added in gaseous form and undergoes a polymerization reaction at 2-4 MPa. 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 sulfidation point monomer is 2:(0.01-0.2). The sulfurization point monomer is selected from , , , , and A combination of one or more of the following; The perfluoromethoxymethyl vinyl ether is CF3OCF2OCF=CF2; The emulsifier is WO-CF2-COONH4, where W represents perfluorinated C. 1-3 alkyl.

2. The preparation method according to claim 1, characterized in that, It satisfies 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 a persulfate and / or a thiosulfate; (4) The initiator is used in the form of an aqueous solution; (5) The initiator may be added all at once, in batches, or continuously; (6) The emulsifier may be added all at once, in batches, or continuously; (7) The polymerization reaction is carried out at 75~90℃; (8) The tetrafluoroethylene is added to the polymerization reaction via a connecting channel so that tetrafluoroethylene gas can be replenished at any time; (9) Controlling the polymerization reaction pressure by adding tetrafluoroethylene gas; (10) The polymerization reaction is carried out at 2.2-4 MPa.

3. The preparation method according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The chain transfer agent is selected from one or more combinations of perfluoro1,2-diiodoethane, perfluorobutyldiiodo, perfluoropentyldiiodo and perfluorohexyldiiodo; (2) The initiator is selected from one or more combinations of potassium persulfate, sodium persulfate, ammonium persulfate, and sodium thiosulfate; (3) The initiator is replenished in the form of an aqueous solution as soon as the polymerization reaction begins; (4) The polymerization reaction is carried out at 80-90℃ or 75-85℃; (5) The tetrafluoroethylene is added to the polymerization reaction via a steel passageway; (6) The polymerization reaction is carried out at 3.2-4 MPa.

4. The preparation method according to claim 1, characterized in that, It satisfies 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 polymerization reaction is carried out at 3.2 or 4 MPa; (5) The polymerization reaction is carried out at 80°C.

5. The preparation method according to claim 1, characterized in that, The sulfurization point monomer is or ,or and ,in and The mass ratio is 1:

1.

6. The preparation method according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The mass ratio of the water to the perfluoromethoxymethyl vinyl ether is (5-20):1; (2) The mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 1:(0.03-0.08); (3) The mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2:(0.03-0.08). (4) The mass ratio of the perfluoromethoxymethyl vinyl ether to the sulfidation point monomer is 2:(0.1-0.15); (5) The mass ratio of the perfluoromethoxymethyl vinyl ether to the initiator is 1:(0.01-1); (6) The initiator is used in the form of an aqueous solution, wherein the mass ratio of the initiator to water is (0.01-1):1; (7) The initiator is added in multiple batches. The first batch is 5-20 v%, and the remaining batch is added continuously. v is the ratio of the added portion to the total volume. (8) The elastomer content in the product obtained by polymerization reaction is 5-30%, which is the mass part of copolymer per 100 parts by weight in water medium.

7. The preparation method according to claim 6, characterized in that, It satisfies one or more of the following conditions: (1) The mass ratio of the water to the perfluoromethoxymethyl vinyl ether is 15:1 or 10:1; (2) The mass ratio of the perfluoromethoxymethyl vinyl ether to the emulsifier is 2:0.1; (3) The mass ratio of the perfluoromethoxymethyl vinyl ether to the chain transfer agent is 2:0.05; (4) The mass ratio of the perfluoromethoxymethyl vinyl ether to the sulfidation point monomer is 2:0.12; (5) The mass ratio of the perfluoromethoxymethyl vinyl ether to the initiator is 1:(0.01-0.1); (6) The initiator is used in the form of an aqueous solution, wherein the mass ratio of the initiator to water is (0.04-0.1):1; (7) The initiator is added in multiple batches, with 15 v% added initially and the remainder added continuously, where v is the ratio of the added portion to the total volume; (8) In the product obtained by polymerization reaction, the content of the elastomer is 5-15% or 10-30%, and the percentage is the mass part of copolymer per 100 parts by weight in water medium.

8. The preparation method according to claim 6, characterized in that, It satisfies one or two of the following conditions: (1) The mass ratio of the perfluoromethoxymethyl vinyl ether to the initiator is 1:0.04; (2) The initiator is used in the form of an aqueous solution, wherein the mass ratio of the initiator to water is 0.08:

1.

9. The preparation method according to claim 1, characterized in that, It includes the following steps: Step (1): Mix the emulsifier, the perfluoromethoxymethyl vinyl ether, the sulfidation point monomer, the chain transfer agent and the water to obtain a mixture, and add it to a tubular reactor; Step (2): Add initiator and tetrafluoroethylene, and carry out the polymerization reaction at a reaction pressure of 2-4 MPa and a reaction temperature of 75-90℃.

10. The preparation method according to claim 9, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The tubular reactor has the following specifications: 2500 mm 100mm; (2) The tubular reactor is made of stainless steel; (3) The polymerization reaction is carried out continuously; (4) The tetrafluoroethylene is added in gaseous form; (5) The rate at which the mixture is added to the tubular reactor is 0.5-10 L / h; (6) 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; (7) The initiator is used in the form of an aqueous solution, and the addition rate is 0.001-0.006 kg / h based on the mass of the initiator; (8) The addition rate of the perfluoromethoxymethyl vinyl ether is 0.03-0.1 Kg / h; (9) First, add 5-20 wt% of the mixture to the tubular reactor, where wt is the mass ratio of the first part to the total mass, and the remaining part is continuously added; (10) The initiator is used in the form of an aqueous solution, with 5-20 v% added. v% is the percentage of the total mass of the first part added, and the remaining part is added continuously.

11. The preparation method according to claim 9, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The polymerization reaction is carried out continuously, and the residence time of the polymerization reaction is 5-15h; (2) The tetrafluoroethylene is added in gaseous form at a reaction pressure of 4 MPa; (3) The rate at which the mixture is added to the tubular reactor is 1 L / h or 5 L / h; (4) 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 66 mL / h; (5) The initiator is used in the form of an aqueous solution, and the addition rate is 0.004 Kg / h or 0.0053 Kg / h based on the mass of the initiator; (6) The addition rate of the perfluoromethoxymethyl vinyl ether is 0.06 kg / h; (7) First, add 15 wt% of the mixture to the tubular reactor, where wt is the mass ratio of the first part to the total mass, and the remaining part is continuously added; (8) The initiator is used in the form of an aqueous solution, with 15 v% added. v% is the percentage of the total mass of the initial addition, and the remaining part is added continuously.

12. The preparation method according to claim 9, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The polymerization reaction is carried out continuously, and the residence time of the polymerization reaction is 10h; (2) The initiator is added in the form of an aqueous solution at a rate of 10-500 mL / h; (3) The initiator is added in the form of an aqueous solution, and the mass ratio of the initiator to the perfluoromethoxymethyl vinyl ether is (1-6):

100.

13. The preparation method according to claim 9, characterized in that, The preparation method satisfies one or two of the following conditions: (1) The initiator is added in the form of an aqueous solution at a rate of 50 mL / h, 66 mL / h or 100 mL / h; (2) The initiator is added in the form of an aqueous solution, and the mass ratio of the initiator to the perfluoromethoxymethyl vinyl ether is 4:

100.

14. The preparation method according to any one of claims 9-13, 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 sulfur point monomer combination: and The mixture is obtained and added to the tubular reactor. Step (2): Add a portion of the initiator aqueous solution to the tubular reactor; Step (3): Inject TFE into the tubular reactor, control the pressure at 4 MPa, and maintain the reaction temperature at 75-90℃; Step (4): The reaction residence time is 10h, the material is discharged, and the mixture and the initiator aqueous solution are continuously added at the same time; Step (5): The obtained liquid is dried, washed, and dried again to obtain the elastomer.

15. An elastomer, characterized in that, It is prepared by the preparation method described in any one of claims 1-14.

16. An application of the elastomer as described in claim 15, characterized in that, The application is for the preparation of low-temperature resistant rubber products.

17. An application of the elastomer as described in claim 15, characterized in that, The application is for manufacturing low-temperature resistant seals.

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